Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model

https://doi.org/10.20965/jdr.2019.p1154 Nakazawa, H. et al.

Paper: Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model Hiroshi Nakazawa∗1,†,KazuyaUsukura∗2, Tadashi Hara∗3, Daisuke Suetsugu∗4, Kentaro Kuribayashi∗2, Tsuyoshi Nishi∗5, Shun Kimura∗6, and Shoji Shimomura∗7

∗1Earthquake Disaster Mitigation Research Division, National Research Institute for Earth Science and Disaster Resilience (NIED) 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan †Corresponding author, E-mail: [email protected] ∗2Eight-Japan Engineering Consultants Inc. (EJEC), Okayama, Japan ∗3Kochi University, Kochi, Japan ∗4University of Miyazaki, Miyazaki, Japan ∗5Construction Project Consultants Inc., Tokyo, Japan ∗6Eight-Japan Engineering Consultants Inc. (EJEC), Tokyo, Japan ∗7Daioh Shinyo Co., Ltd., Kochi, Japan [Received April 5, 2019; accepted August 30, 2019]

The earthquake (Mw 7.3) that struck Nepal on Keywords: gabion retaining wall, earthquake-resistant April 25, 2015 caused damage to many civil engi- design, shake table test, trial wedge method, active col- neering and architectural structures. While several lapse angle road gabion retaining walls in mountainous regions in- curred damage, there was very little information that could be used to draw up earthquake countermea- 1. Introduction sures in Nepal, because there have been few construction cases or case studies of gabion structures, nor The earthquake (Mw 7.3) that struck Nepal on April 25, have there been experimental or analytical studies on 2015 caused damage to many civil engineering and archi- their earthquake resistance. Therefore, we conducted tectural structures. In Kathmandu, many of the older, tra- a shake table test using a full-scale gabion retaining ditional brick structures in the historical district collapsed, wall to evaluate earthquake resistance. From the ex- while reinforced concrete (RC) structures, some of which periments, it was found that although gabion retain- were relatively recently built, were also damaged. While ing walls display a flexible structure and deform eas- much of the damage to the new RC structures was likely ily due to the soil pressure of the backfill, they are re- due to inadequate anti-seismic construction, some struc- silient structures that tend to resist collapse. Yet, be- tures remained undamaged because of their earthquake- cause retaining walls are assumed to be rigid bodies in resistant design in accordance with the Nepal National the conventional stability computations used to design Building Code [1], which was adopted recently. Mean- them, the characteristics of gabions as flexible struc- while, much of the damage in the river basins in moun- tures are not taken advantage of. In this study, we pro- tainous regions was induced by rainfall in addition to pose an approach to designing gabion retaining walls the earthquake, including slope collapse and landslides, by comparing the active collapse surface estimated by which blocked the only local community road and pro- the trial wedge method, and the experiment results ob- duced natural dams when mud clogged the rivers. tained from a full-scale model of a vertically-stacked The authors [2] conducted three field surveys, in July wall, which is a structure employed in Nepal that is and November 2015, and in November 2016, of the dam- vulnerable to earthquake damage. When the base of age to the gabion road retaining walls along the Araniko the estimated slip line was raised for the trial wedge Highway in mountainous regions, and have previously re- method, its height was found to be in rough agree- ported the findings. The use of gabions as reported by ment with the depth at which the gabion retaining Nakazawa et al. [3], shown in Fig. 1, indicates that, of wall deformed drastically in the experiment. Thus, we the 115 locations, 49%, or approximately half, were used were able to demonstrate the development of a method as road retaining walls, and 19% as crash barriers. Ta- for evaluating the seismic stability of gabion retaining ble 1 presents a summary of the damage status of the walls that takes into consideration their flexibility by retaining walls and crash barriers that were most often adjusting the base of the trial soil wedge. found in these surveys, where the damage level is divided into the three categories of A, B, and C. Categories A, B, and C indicate no damage, bulging, and collapse, respec-

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© Fuji Technology Press Ltd. Creative Commons CC BY-ND: This is an Open Access article distributed under the terms of the Creative Commons Attribution-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nd/4.0/). Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model

Fig. 1. Breakdown of gabion structures along Araniko Highway (adapted from [3]). Category A refers to retaining walls judged to be undamaged in the damage survey, B to those that were partially deformed or bulged out, and C to those that had collapsed. The broken lines and arrows in photos B and C indicate the deformed or collapsed range of the retaining wall and its direction.

Table 1. Summary of survey results of retaining walls and crash barriers (adapted from [3]).

Investigation results Ways to lay gabions Main stone forms packed in gabions Others Angular Loose Structure Number of Angular or Damage Vertical Stepwise Total steps and structures type investigated trimmed for Roundish type∗ type type of gabions roundish partly places inﬁll work mixture including A 21 11 10 2–5 18 2 1 3 Retaining walls B 27 11 16 2–5 23 1 3 2 C 9 3 6 2–7 6 1 2 2 A 8 – – 1–3 2 3 3 2 Crash barrier B 8 – – 1–2 1 5 2 7 C 6 – – 1–2 2 2 2 1 *) A: No major damage; B: Partial deformation; C: Collapse

tively. Among the road retaining walls studied in this pa- quake countermeasures in Nepal. Therefore, following per, vertically-stacked and stepped types each constituted the above-mentioned survey, we conducted a shake ta- roughly half of category A, while the stepped structures ble test using a full-scale gabion retaining wall in order exceeded the vertically-stacked structures in categories B to evaluate their earthquake resistance employed in Nepal and C. Although vertically-stacked construction is rarely that tended to become damaged in the recent earthquake, used at Japanese construction sites due to its instability as as well as a structural form for the purpose of proposing compared to the stepped type, it is characteristic of Nepal future earthquake-resistant structures. From this series of and is often used. experiments, it was found that, although gabion retain- It is essential that reconstruction is executed rapidly af- ing walls display a flexible structure and deform easily ter an earthquake to recover residents’ former daily lives due to the soil pressure of the backfill, they are resilient and economic activities, and it is desirable for the recon- structures that tend to resist collapse [4]. Yet, because struction results to serve as permanent structures and not retaining walls are assumed to be rigid bodies in the con- be used just for temporary relief purposes. There is a rel- ventional stability computations that are used to design ative scarcity in Japan of construction examples or case retaining walls, the advantages of gabions and other flex- studies of gabion structures that serve as permanent fa- ible structures are not fully used. cilities, and of experimental or analytical studies on their Thus, in this paper, Section 2 reviews previous stud- earthquake resistance, with the result that there is very lit- ies and investigations, Section 3 outlines the experimental tle information that could be useful for drawing up earth- results necessary for the present study, referring to the re-

Journal of Disaster Research Vol.14 No.9, 2019 1155 Nakazawa, H. et al.

sults of the shake table test conducted previously by the tion of the virtual back surface for inverted T- and L-type authors, and Section 4 examines the applicability of the retaining walls, and proposed an improved trial wedge trial wedge method to gabion retaining walls, which is the method, assuming that two slip lines are generated in the objective of this study. As a first step toward practical de- backfill. sign, we apply the trial wedge method to estimate the ac- The above brief survey indicates that retaining walls tive collapse surface in a vertically-stacked gabion retain- have conventionally been treated as rigid bodies, without ing wall reported in a previous full-scale experiment, and any consideration for the deformation of the retaining wall we then propose an approach to, and discuss problems re- itself. In those cases where they are treated as flexible lated to ultimately establishing a design methodology for structures, stability is ensured by adopting a leaning-type gabion retaining walls. structure, while few studies exist that examine a flexible gabion structure as a vertically-stacked wall.

2. Previous Studies and Design/Construction Examples 3. Shake Table Test Using Full-Scale Retaining Wall Model Conventional studies of the seismic stability of retaining walls generally examine concrete gravity, inverted 3.1. Outline of Experiment T-shape, L-shape, leaning, and reinforced earth retain- The full-scale model experiment referred to in this ing walls. For instance, Watanabe et al. [5] conducted study was conducted by Nakazawa et al. [3] to examine a model shake test using retaining walls of various types, the seismic resistance performance and dynamic behavior and systematically evaluated their seismic stability, soil during earthquakes of gabion retaining walls, and it has pressures, and phase characteristics during earthquakes. been reported in detail. There are other reports [4, 15] re- In this study, the measured soil pressure during an earth- garding this research, which are also referred to, where quake was lower than the computed values based on the those items relevant to the stability computation consid- Mononobe-Okabe formula [6, 7]. One of the reasons for ered in this study are summarized from this section to this was that the response acceleration and phase of the Section 3.6. sliding earth mass in the retaining wall backfill differed Although onsite field surveys [2] determined that the substantially from those of the substrate. gabions used locally in retaining walls varied in size ac- There are relatively few studies of gabion retaining cording to the local conditions, many had the rough di- walls, even though they are commonly used both in mensions of 100 cm in width, height, and depth. There- Japan and overseas. Ramli et al. [8] studied the stabil- fore, we adopted this size in the full-scale model experi- ity of gabion retaining walls used as earth-retaining struc- ment, constructing a retaining wall with a height of 3 m. tures. They examined stability by comparing interlocking In a series of experiments [4], three different retaining configurations of rectangular and hexagonal gabions and wall configurations were tested (cases 1, 2, and 3). The found that the hexagonal gabion retaining wall had supe- stability computation in this paper was carried out for rior stability. a three-tiered vertically-stacked structure, which is not Furthermore, as an example of a study on gabion re- found in Japan, but is characteristically used along the taining walls in Japan, Guide and Commentary on Gabion Araniko Highway and which is typed as “case 1.” We Engineering Method [9] provides a design and computa- examine this structure to contribute to the reconstruction tion case. Regarding a similar structure, another group efforts in Nepal and to propose design improvements. The examined the seismic resistance of leaning retaining walls model specifications are presented in Fig. 2 and Table 2. constructed with stacked precast blocks [10–12]. In the former case, the gabion retaining wall backfill was given agradientof1:1.5, while the cage stacking gradient of 3.2. Experiment Materials and Preparation the gabion retaining wall, 1 : n, varied between n = 0.3 Based on the description of materials used in the test and n = 1.0. The normal (i.e., non-earthquake) stability specimens given by Nakazawa et al. [3], the items related of an 8.0 m high retaining wall was evaluated. Yet, retain- to the preparation of the test specimens are summarized ing walls with heights of 8 m and below do not normally below. require an assessment of seismic stability and, in practice, In Nepal, the government guidelines specify the gabion their design and construction are either based on existing wire mesh, the filling stones, and the construction guidelines or experiential rules [13]. method [16]. Because it was difficult to obtain the lo- In the trial wedge method applied to the experimental cal product used for the gabion wire mesh, we employed results of this study, the acting earth pressure is computed 3.2 mm diameter steel wire, configured to form a rhom- by assuming the slip surface against the gravity-type re- bic wire mesh with a 13 cm mesh size (conforming to JIS taining wall. The Road Construction Works on Soil – Re- A 5513). Suetsugu et al. [17, 18] reported that the use of taining Wall Guidelines [13] also discusses the structural binding between gabions has the effect of increasing the forms of inverted T-shape retaining walls, which are of- deformation resistance regardless of the shape of the filled ten used in practice. Ushiro et al. [14] have pointed out stones. Therefore, binding between gabions was used in the problems involved with setting the angle of wall fric- this experiment as well.

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Fig. 2. Cross section of full-scale experiment (case 1) [3]. The large arrows indicate the measurement directions of the displacement sensors. The compacted surface indicates the target construction height, and the entire backﬁll surface was rolling-compacted (longitudinally 8 m in length).

Table 2. Characteristics of experiment cases (adapted from [3]).

Gabion retaining wall Ground model Input Experimental acceleration Feature of each case Density Wet density Water content Degree of case Structure 3 3 compaction [Gal] ρ [t/m ] ρt [kN/m ] Wn [%] Dc [%] The most common structural form con- Case 1 65, 132, 203, structed along the Araniko Highway in Vertical- 15.80 17.09 5.0 86.4 and 257 Nepal, and a fragile structure that is easy type to deform.

The diameter of the rubble stones used as the filling the top, and the filling stones were carefully placed one material was 15–19 cm, whereas the stones were mostly by one manually. The horizontally and vertically adja- in the size range 20–24 cm in Nepal, which is larger than cent gabions were bound by wires. For the model earth the present experiment. The modulus of deformation Et50 fill, a 50 cm thick foundation substrate was installed in of the filling material core was 42.3 and 54.2 GN/m2 in the soil container, as shown in Fig. 2, on top of which the experiment, and 48.2 GN/m2 in the case of the sam- decomposed granite soil was laid. Nine to ten soil lay- ples used locally in Nepal. The uniaxial compression ers (to a 3.0 m height) were used, where each layer was 2 strength qu was 109.1 and 199.0 MN/m in the experi- spread to a thickness of 30–35 cm and then compacted ment, and 124.3 MN/m2 in the samples in Nepal. Thus, by rolling. Rolling compaction was carried out five times the deformation and strength characteristics of the two for each layer to produce a compaction degree Dc of ap- cases were in rough agreement [3]. proximately 90%, as determined from a preliminary ex- The backfill of the model consisted of decomposed periment. The average moisture content wc of the model granite soil (Masado), or φ-soil, which is characterized as earth was 5.2% during construction. The brown down- being mostly composed of gravel and sand fractions. The pointing arrows indicate the compacted surface heights in maximum dry density ρdmax used for construction man- Fig. 2, and the final backfill ground after construction had 3 agement during model construction was 1.884 g/cm [3]. an average compaction degree Dc of 86.4% [3]. We next describe the construction of the experimental model. The gabion retaining wall was constructed by assembling the gabion wire mesh, placing the gabions 3.3. Shaking Conditions in specified positions, i.e., three gabions side by side to To observe the dynamic behavior during shaking, ac- form a single row in the soil container. Top stretchers celerometers were placed on the gabion retaining wall and were installed to prevent the gabions from bulging out at in the backfill at the positions shown in Fig. 2.Forall

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Fig. 3. Time history data obtained from the 132 Gal shake test (adapted from [4]). The legends and data of (a)–(d) are based on the sensor positions given in Fig. 2, and show the acceleration and displacement responses of the test model when shaken at 132 Gal. (a) shows the horizontal displacements of the retaining wall toward the front measured by displacement sensors LD-01H and G-WD-01 to -06, installed from top to bottom. (b) shows the measurements of the displacement sensors installed at the crest of the gabion retaining wall and the backfill surface: the upper graph shows horizontal displacements of the gabion retaining wall crest (G-WE-01G) and the backfill surface from the retaining wall to the rear (LD-01H to -05H), and the lower graph the vertical displacements at the same locations on the backfill surface where horizontal displacements were measured (LD-01V to -05V) (+ values indicate subsidence). The six graphs of (c) show the acceleration responses of the front of the retaining wall from top to bottom (G-ACC-01H(V) to -06H(V)), as in (a), where H and V respectively indicate the horizontal (+ is toward the front of the retaining wall) and vertical (+ values indicate subsidence) accelerations. The six graphs of (d) show the measurements of accelerometers installed at the rear of the gabion retaining wall and in the backfill. G-ACC-07H to -12H form pairs with the corresponding sensors at the retaining wall front, shown in (c), while the accelerometers in the backfill (for example, ACC-02, -06, and -10 in the second graph from the top) are installed at the same heights as those at the retaining wall rear (G-ACC-08H and -09H), arranged from the retaining wall toward the backfill center. (e) shows the acceleration response of the shake table used for the experiment and represents the input conditions for the model.

cases, six units were installed at both the front and back tions. of the gabion retaining wall, while units were positioned The input wave used to apply shaking consisted of a in the backﬁll at heights of approximately 1.0 m, 2.0 m, sinusoidal wave of 3 Hz, which is close to the resonant and 3.0 m at three different distances from the retaining frequency of the gabion retaining wall standing alone as wall. Draw-wire displacement sensors were installed at found from an experiment, and lasted 8 s, including the six heights at the front of the retaining wall, while laser gradual-rise, steady-state, and gradual-fall sections. The displacement meters were installed at four locations on waveform is shown in Fig. 3(e), which shows the experi- the backﬁll surface in the horizontal and vertical direc- ment results described later. To apply shaking, four differ-

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Fig. 4. Time history data for the steady-state section of sinusoidal wave (adapted from [4]). (a) to (d) show the respective data of the four acceleration tests, corresponding to the data for t = 2 − 6 s of the acceleration given in Fig. 3(e). (a),(b),(c),and(d) respectively show experiment data for the four stages of input conditions 65 Gal, 132 Gal, 203 Gal, and 257 Gal. The legend indicates the sensors shown in Fig. 2. The uppermost row shows the horizontal displacements of the gabion retaining wall crest and nearby backﬁll surfaces. The second to fourth rows show accelerations of the back of the gabion retaining wall and adjacent backﬁll at increasing depths.

ent levels of input acceleration were applied, as presented ond acceleration stage at which the backfill began to dis- in Table 2 [3]. play damage, as reported by Nakazawa et al. [4]. From In addition to the measurements taken during the shak- the time histories of the horizontal displacement of the ing, 3D laser measurements were taken before and after crest of the gabion retaining wall (G-WD-01, LD-01H), the shaking test to determine the residual deformations shown in Fig. 3(a), and the horizontal and vertical dis- of the gabion retaining wall, as reported in Nakazawa placements of the backfill surface (LD-02H to LD-05H, et al. [4]. LD-02V to LD-05V), shown in Fig. 3(b), it can be seen that the horizontal displacement of the front of the retaining wall and surface subsidence of the backfill increased 3.4. Outline of Experiment Results as shaking was applied. Meanwhile, behind the retain- We describe the time history and tendency of residual ing wall, the upper sections of the retaining wall display deformation found in the experiment results for case 1. acceleration amplitudes that are greater than those of the The horizontal displacement of the retaining wall builds backfill proximate to the retaining wall, a tendency that during the shaking, and cracks occur in the backfill with was especially pronounced at the topmost (tier 3) gabion. the horizontal displacement of the retaining wall. When Next, in order to examine the detailed behavior of and an acceleration of 132 Gal, which is the second accel- changes in the gabion retaining wall and backfill for all eration stage presented in Table 2, was applied, a large four cases, Fig. 4 shows enlarged views regarding to the crack occurred on the surface of the backfill at a distance horizontal displacements and acceleration responses from of 1.1 m from the retaining wall, and caused the back- the retaining wall rear to the backfill ranged within 4 m, fill earth to collapse and the retaining wall to lean for- which corresponds to the steady-state section of the si- ward considerably. When the four-stage shaking process nusoidal wave for t = 2 − 6 s, as reported by Nakazawa was over, it was observed that the retaining wall leaned et al. [3]. heavily forward, and the backfill had substantially col- For the input acceleration of 65 Gal, it can be seen that lapsed [3, 4]. the acceleration responses of the gabions (G-ACC-07H, -09H, -11H, -12H) and the backfill (ACC-01, -02, -03, -04) generally match, indicating that they are moving as a 3.5. Dynamic Behavior single unit. Figure 3 shows the time history data of case 1 when For the next acceleration stage of 132 Gal, the hori- an acceleration of 132 Gal was applied, which is the sec-

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zontal displacements of the gabion wall rear and the adjacent backfill section (LD-01H and LD-02H) increase together with excitation, although the backfill central section (LD-03H) displays hardly any displacement. At the lower part of the retaining wall, the acceleration responses of the retaining wall rear (G-ACC-11H and -12H), adjacent backfill section (ACC-03 and -04), and central backfill section (ACC-07 and -08) are roughly in agreement. Meanwhile, at the retaining wall crest, the acceleration response of the gabions (G-ACC-07H) roughly matches that of the adjacent backfill section (ACC-01) but displays a phase difference with that of the backfill central section (ACC-05). When the excitation acceleration was increased to 203 Gal, and further to 257 Gal, the laser displacement sensor at the retaining wall crest, LD-01H, was unable to capture its target, so the data recorded by G-WD-01, installed at the same height at the front of the retaining wall, was added. At 203 Gal, the horizontal displacement of the crest of the gabion retaining wall (G-WD-01) is accumulated, while that of the adjacent backfill section Fig. 5. Deformation of the front of the gabion retaining (LD-02H) displays no residual horizontal displacement. wall [3]. The vertical broken arrows indicate the positions The acceleration response of the crest of the topmost of the gabions. The legend indicates the four acceleration gabion (G-ACC-07H) displays a substantial phase differ- levels (input conditions). ence from that of the adjacent backfill section (ACC-01). Meanwhile, the acceleration responses of the gabion retaining wall at the second layer (G-ACC-09H) and near the bottom (G-ACC-11H) are attenuated. It has been pre- 4. Stability Computation for Full-Scale Exper- viously reported that the phase shift observed between the iment accelerations of the gabions (G-ACC-09H) and the adjacent backfill section (ACC-02) was due to the presence Based on the results of the full-scale experiments, of sliding earth mass and loose sections [15]. It is evi- Nakazawa et al. [4] demonstrated that a stepped or dent that this tendency becomes more pronounced when gravity-type gabion retaining wall, if feasible in terms of the excitation was further increased to 257 Gal. cost and construction time, would be more effective than a To summarize the above findings with reference to our vertically-stacked gabion retaining wall, which was found previous studies, a phase difference occurred between the to be prone to earthquake damage in Nepal, and pointed gabion wall upper section and the topmost layer of the out the need to establish a design method specifically for adjacent backfill section when the model was subjected to gabion retaining walls. Because the earthquake force is an excitation of 132 Gal, resulting in cracks in the back- conventionally replaced by a static horizontal force as a fill. As the excitation acceleration was increased, the dam- first step, this study examines the application of the trial age to the backfill expanded and caused the sliding earth wedge method against the full-scale experiment model. mass to become loose, thus attenuating its acceleration re- Although the trial wedge method is a universal tech- sponse. nique commonly applied to concrete gravity-type retaining walls and other rigid structures, there are a few 3.6. Residual Deformation computational examples of its application to gabion- construction retaining walls, including in the handbook Figure 5 shows the deformations of the entire surface mentioned in Section 2 [9]. Gabions were employed in of the gabion retaining wall for each excitation. The plots a leaning retaining wall in this case, with no discussion indicate the positions of the displacement sensors after included of vertically-stacked walls. In this study, we excitation. It is evident that the retaining wall deforms apply the conventional trial wedge method, as presented further to the front each time the excitation level is in- in Road Construction Works on Soil – Retaining Wall creased. The deformation of the gabions at the second Guidelines [13], because the previous experiment to be layer was particularly pronounced, causing a horizontal discussed was conducted with a simple vertically-stacked displacement of approximately 80 cm at the retaining wall wall. crest, although the retaining wall remained standing as it Meanwhile, the present experiment results indicate that leaned forward at an angle of approximately 18◦. retaining walls constructed from highly flexible structures such as gabions display pronounced deformations in their upper sections. In particular, the dynamic behavior described in Section 3.5 indicates that the upper section of

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Fig. 6. Comparison of active collapse lines and crack locations [19]. The thick arrows at the backﬁll surface indicate the crack locations when excited at 132 Gal and 203 Gal; the bold line indicates the active collapse surface under normal conditions; the thin lines indicate the estimated active collapse surfaces; the solid box indicates the loose area conﬁrmed by the cone penetration test (downward arrows).

the retaining wall and the adjacent backfill section tend then compared the estimated active collapse angles and to display a phase difference, producing a sliding earth the observed surface cracks. mass or loose area to the rear of the retaining wall upper section, and this zone expands as the acceleration level 4.1. Estimation of Active Collapse Angle of Backfill is increased. As a result, the horizontal displacement of and Evaluation of Lateral Seismic Coefficient the retaining wall upper section increases, as is shown in Figure 7 shows a schematic of the trial wedge method. Fig. 5. Therefore, the estimated slip angle in the back- In the trial wedge method, the maximum soil pressure is fill may diverge from actual values when it is calculated determined by varying the angle of the slip surface by trial for a retaining wall with such deformation characteris- and error. In other words, the soil pressure acting on the tics. Usukura et al. [19] applied the trial wedge method wall is determined from the balance of forces acting on to evaluate the slip surface of the backfill of a full-scale the soil mass just before it collapses, taking into consider- vertically-stacked retaining wall in order to assess the sta- ation the condition of the wall, assumed slip surface, and bility of the gabion retaining wall. In accordance with ground surface. the Road Construction Works on Soil – Retaining Wall Figure 7(a) shows a diagram adapted from the Road Guidelines [13], they conducted a parametric study us- Construction Works on Soil – Retaining Wall Guide- ing a parameter range of horizontal seismic intensity, kh, lines [13]. When the banked slope gradient β, angle α of 0.1–0.5, and estimated the active collapse angle. They formed by the back side of the wall and a vertical plane, then compared the active collapse line and the position angle of wall friction δ, and cohesion c and cohesive of surface cracks observed in the experiment, as shown height z of the backfill are set to zero, we obtain Fig. 7(b), in Fig. 6. Based on the estimated slip angles, they found the cross section modified to the conditions considered in that, when a sinusoidal excitation of 132 Gal was applied, this study. To consider the soil pressure during an earth- cracks occurred in the collapsed zone of the backfill of the quake, we consider the link polygon, shown in Fig. 7(c), gabion retaining wall inside the normal (non-excitation) consisting of the active composite soil pressure P, reac- slip line indicating normal stability in the absence of seis- tion acting on the slip surface R, weight W of the soil mic force. wedge, and its inertial force k W, which includes the lat- Because it is difficult to strictly account for the flexible h eral seismic coefficient kh. structure of the gabion retaining wall, we evaluated the Using Eq. (1), we estimate the active collapse angle ω stability of the gabion retaining wall by varying the height for k values of 0.1–0.5. of the base of the trial wedge. To this end, we applied the h W · secθ · sin(ω − φ − θ) trial wedge method using a varying wedge base to the ex- P = ...... (1) periment results when 132 Gal and 203 Gal, respectively cos(ω − φ − α − δ) corresponding to the second and third excitation stages, The variables of Eq. (1) are defined in Fig. 7,whereω were applied to the full-scale vertically-stacked wall. We is the only unknown parameter, so that Eq. (1) is a func-

Journal of Disaster Research Vol.14 No.9, 2019 1161 Nakazawa, H. et al.

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Fig. 7. Assumptions of slip surface in trial wedge method (adapted from [13]). (a) shows a model diagram of a general slip surface, (b) the model diagram for conditions used in this study based on (a), and (c) the link polygon, which shows the balance of forces during excitation for (b). The symbol H denotes the retaining wall height [m], z the cohesive height (depth of tension crack), l the 3 length of the assumed slip surface [m]. The design parameter W denotes the weight of the soil wedge [kN/m ], kh the horizontal seismic coefficient, φ the shear resistance angle [◦]ofthebackfill,andc the cohesion of the backfill [kN/m2]. With regard to the forces and their directions, θ is the composite seismic angle [◦], ω the angle between the assumed slip surface and horizontal plane [◦], β the backfill slope gradient [◦], δ the wall friction angle [◦], and α the angle between the wall back surface and the vertical plane [◦].

Table 3. Input values.

Item Symbol Value Unit Remarks Mass per unit volume γ t 17.09 [kN/m3] From soil test Height of backﬁll H 3.0 [m] Height of backﬁll Angle of internal friction φ 38.0 [◦] From soil test Angle between wall back and vertical plane α 0 [◦] Zero since wall rear is vertical Slope gradient β 0 [◦] Zero slope angle Wall surface frictional angle δ 19.00 [◦] Angle of internal friction × 1/2 (during earthquakes) Cohesion c 0 [kN/m2] From soil test

tion of P and ω. By setting the conditions of Eq. (2), we in this experiment is higher than the base of the retain- obtain ω. ing wall, and we estimated the base of the active col- dP d2P lapse surface for the trail wedge method. It can be seen = 0, = 0...... (2) from Fig. 6 that the second shaking test using 132 Gal dW dW2 produced cracks inside the normal slip surface, indicat- The major input values are presented in Table 3.Be- ing the unsuitability of a straightforward application of cause the frictional force at the back of the gabion retain- the trial wedge method. In this investigation, we checked ing wall is unknown, we assume it to be 1/2ofthean- whether the trial wedge method could be applied for the gle of internal friction, as in the Guidelines. It should second excitation of 132 Gal, and, for the third excitation be noted, however, that the gabion retaining wall actually of 203 Gal, we shifted the base of the active collapse sur- has a rough, uneven surface due to the filled stones, unlike face according to the most distant surface crack (at 2.8 m) other materials such as concrete. from the retaining wall, and determined the lateral seis- The results of 3D laser measurement are shown in mic coefficient kh acting on the earth mass assumed for Fig. 8, based on which the collapse and crack locations the trial wedge method. in the backfill according to the excitation level are sum- Figure 9 shows the active collapse surfaces used to Table 4 marized in . The locations of the major surface compute kh for the two excitation conditions. It can be Fig. 6 cracks are also shown in . seen that kh increases as the base of the trial wedge is As shown in Fig. 6, when the base of the trial wedge is raised. This is because the lighter earth mass that re- positioned at the base of the back of the gabion retaining sults from raising the base requires greater acceleration wall to estimate the active collapse surfaces of the back- to reach the required inertial force. In Fig. 9(a), the base fill, the active collapse surface was estimated to occur fur- must be raised to bring the slip line to the observed crack ther back than the observed crack positions. Therefore, location. This is because the crack occurred behind the we assumed that the base of the active collapse surface retaining wall inside the normal slip line.

1162 Journal of Disaster Research Vol.14 No.9, 2019 Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model weighted based on their weights (proportional to cross- section areas), to compute the acceleration α acting on the entire soil mass. We give an example of the computation of α using base 3, in which case the soil wedge is given by solid lines. When base 3 is used, the soil wedge is divided into two trapezoidal sections, W1 and W2,and a triangular section, W3. Using the measurement results of the accelerometers in the experiment, the accelerations at the depths corresponding to the block centroids are determined, and they are multiplied by the respective block areas. The sum of these products is then divided by the total area of the soil wedge to determine the acceleration acting on the soil wedge. The computed α is then divided by the acceleration of gravity, 1 G, to convert it to kh (= α/g). In the case where base 2 is used, the computation is carried out using blocks W1 and W2, indicated by the broken lines. In this study, we use the acceleration responses in the model backfill during the shake test and compare the kh estimated in the previous section with the kh which was directly determined from the test results. Figures 12 and 13 show, respectively for accelerations of 132 Gal and 203 Gal, the residual deformations of the front of the gabion retaining wall, the depth distribution of the acceleration responses, and the relation between the lateral seismic coefficient and wedge base height. Fig. 12(a) shows the residual deformations of the front of the gabion retaining wall, Fig. 12(b) the distributions of the acceleration responses α measured by ACC-01 to -04, ACC-05 to -08, and ACC-09 to -12, and Fig. 12(c) the values of kh obtained from the shake test based on Fig. 8. Results of 3D laser measurements ( indicates posi- Fig. 12(b). tions of subsurface exploration) [3]. The circles indicate the In Fig. 13(b), the peak values of the data recorded by positions of the cone penetration test, the solid lines before ACC-01 to -04 are used representatively for the backfill shaking the outer boundary of the gabion retaining wall, the adjacent to the gabion retaining wall, which displayed solid lines after shaking the outer boundary of the retaining drastic deformation. A substantial shift occurred because wall, the dotted lines in the top view of the backfill surface and arrows the surface cracks, while the broken lines shown the area between the gabion retaining wall and backfill in the front-side views indicate the heights of the gabion lay- became loose due to the phase difference, as explained ers before shaking, and the solid lines after shaking indicate earlier in reference to Fig. 4, which caused the accelerom- the gabion layer heights after shaking. eters at the second layer and at the top of the gabion retaining wall to become inclined. Meanwhile, the residual deformation of the front of the gabion retaining wall is pronounced at the topmost and second layers, which 4.2. Comparison of Estimated Slip Lines and Ex- is in agreement with the distribution of α in ACC-01 to periment Results -04. However, these accelerations cannot be directly used The accelerometer positions are also given in Fig. 9, to quantitatively evaluate the external force acting on the which shows the distribution of the estimated slip lines. soil mass, and so were not used to compute kh. This allows calculation of the inertial forces and actual Looking at the measurements of ACC-05 to -08 and kh acting on the earth masses during the shaking tests. ACC-09 to -12, we see that the acceleration response pro- Conventionally, the base of the slip line is set at the base gressively increases toward the surface. When subjected of the retaining wall, as shown in Fig. 10(a), without to excitations of 132 Gal and 203 Gal, ACC-05, which accounting for the deformation of the gabion retaining lies at the surface closer to the retaining wall, recorded wall. However, the soil wedge that occurs in the back- 204 Gal and 506 Gal, respectively, while ACC-09, which fill will have a limited range depending on how deformed lies at the center of the backfill, recorded 181 Gal the gabion retaining wall becomes, and so we assume the and 436 Gal, respectively. Based on these cross-section virtual bases shown in Figs. 10(b) and (c). Fig. 11 shows distributions of acceleration, kh was computed assuming the manner in which the soil wedges were extracted to that the base of the soil wedge was located at the very compute the acceleration acting on them. The soil mass bottom, and at points 1.0 m and 2.0 m above the founda- in the backfill is divided into 1 m high blocks, based on tion subgrade using the computational method shown in the heights of the gabion units, and the soil masses are Fig. 11. Figs. 12(c) and 13(c) show the relation between

Journal of Disaster Research Vol.14 No.9, 2019 1163 Nakazawa, H. et al.

Table 4. Summary of backﬁll damage (from [4]).

Experimental case Structure type Input acceleration [Gal] Aspect of back ground Collapse area 65 No change No change Crack occurred 0.7 m behind retaining wall, and 132 ∼0.7 m Case 1 Vertical type slip collapse occurred Cracks occurred at 1.1 m, 1.6 m, 2.1 m, and 203 ∼0.7 m 2.8 m 257 Slip collapse within range of 1.1 m ∼1.1 m

Fig. 9. Distribution of estimated slip surfaces. (a) shows the estimated slip surfaces for the second shaking test, conducted with 132 Gal, and (b) those for the third shaking test, with 203 Gal. The diamonds () indicate the accelerometer positions, and the arrows on the surface indicate the locations where cracks occurred after shaking: the arrow outlined with broken lines is for the second shake test (132 Gal), and those outlined with solid lines are those for the third test (203 Gal). The broken line in the backﬁll indicates the collapsed region observed in the experiment, and the solid lines the estimated active collapse surfaces.

1164 Journal of Disaster Research Vol.14 No.9, 2019 Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model

Fig. 10. Relation of deformation of gabion retaining wall and soil wedge. (a) shows the conventional base position and a substantially deformed gabion retaining wall, while (b) and (c) show how deformation restricted to the upper section of the gabion retaining wall becomes smaller, resulting in decreased height of the virtual soil wedge.

2 Fig. 11. Diagram showing computation of acceleration. W1–W3 denote the areas [m ] of the assumed soil wedges, α1–α3 the computed accelerations [Gal] acting at the centroids of the respective blocks, and α the acceleration [Gal] acting on the entire soil α α =( n )/( n ) wedge. is given by the following expression: ∑i=1 WiAi ∑i=1 Wi ,wheren denotes the number of soil wedge blocks (n ≤ 3) according to the base height.

the height of the base of the wedges and kh, as determined a height of 1.3–1.4 m, which produces a kh value slightly earlier in Fig. 9, together with the kh values computed higher than 0.4. These heights of the wedge base respec- from the experiment results for comparison. Note that, in tively correspond to the tops of the second and first gabion Fig. 12(c), kh was not computed for the case where the layers from the bottom of the retaining wall. This can base of the soil wedge lies at the bottom of the retain- be confirmed from the deformation shapes of the front of ing wall, because the distance between the crack in the the retaining wall, shown in Figs. 12(a) and 13(a),which backfill and the retaining wall was short, at 0.7 m. Fur- display pronounced deformations above the respective ar- thermore, the acceleration was also measured at ACC-13 rows. Furthermore, it can be seen in Fig. 4 that the ac- to -16, which lies furthest from the retaining wall, but celeration amplitude increases at the top of the bottom these measurements, as well as those of ACC-01 to -04, gabion layer during the 132 Gal shake test, and that there were not considered in this study because of the possible is a phase difference between sections of the retaining influence of reflected waves from the soil container wall. wall above the top of the second layer and the backfill In Figures 12(c) and 13(c), it can been seen when excited at 203 Gal. Such agreement between the that kh = 0.2, corresponding to a wedge base height deformation tendency or dynamic behavior of the gabion of 2.1–2.2 m, as determined from the trial wedge method retaining wall and the height of the wedge base suggests for 132 Gal excitation, fits with the results of ACC-05 that it is possible to apply the trial wedge method to flex- to -08, which lie close to the soil wedge. For an excitation ible gabion retaining walls by raising the height of the of 203 Gal, agreement is seen when the wedge base has wedge base.

Journal of Disaster Research Vol.14 No.9, 2019 1165 Nakazawa, H. et al.

Fig. 12. Confirmation of the validity of the method to determine the lateral seismic coefficient based on the deformation and acceleration response of the gabion retaining wall obtained from the 132 Gal shake test. (a) shows the deformed shape of the front of the retaining wall after the shake test, (b) the depth distribution of the acceleration responses of the backfill adjacent to (ACC-01 to -04), and further away (the two rows, ACC-05 to -08 and ACC-09 to -12) from the gabion retaining wall, shown in Figs. 2 and 9, and (c) shows a comparison of the depth distribution of the experiment results and lateral seismic coefficients for different base heights computed using the method shown in Fig. 11. The lowest base height of the estimated lateral seismic coefficient is 1.5 m, which corresponds to the height of the base of the slip line under normal conditions (kh = 0.00), shown in Fig. 9(a).

Fig. 13. Confirmation of the validity of the method to determine the lateral seismic coefficient based on the deformation and acceleration response of the gabion retaining wall obtained from 203 Gal shake test. (a) shows the deformed shape of the retaining wall front after the shake test, (b) the depth distribution of the acceleration responses of the backfill adjacent to (ACC-01 to -04) and further away (the two rows, ACC-05 to -08 and ACC-09 to -12) from the gabion retaining wall, shown in Figs. 2 and 9, and (c) shows a comparison of depth distribution of the experiment results and lateral seismic coefficients for different base heights computed based on the method shown in Fig. 11.

5. Conclusion and Issues for Design as permanent structures and not be used just for temporary relief purposes. The results of previous shake table tests It is necessary, in an effort to restore gabion retaining showed that, although gabion retaining walls are flexible walls in Nepal following the recent earthquake, to develop structures that deform easily due to the backfill soil pres- a design method specifically targeted at gabion retaining sure, they are resilient structures that tend to resist col- walls. It is desirable for the reconstruction results to serve lapse. Yet, the conventional stability computations used

1166 Journal of Disaster Research Vol.14 No.9, 2019 Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model to design retaining walls assume rigid structures, such K. Usukura, R. Shibahara, and K. Tabata, “Full-Scale Model Ex- periment and Development of Evaluation Method for Earthquake- as concrete gravity-type retaining walls, so that the ad- Resistant Road Retaining Wall Using Gabions – Process Until Ap- vantages of gabion and other flexible structures are not plication of the Proposal Method from On-Site Damage Survey in Nepal Site –,” Technical Note of the National Research Institute for made full use of. In other words, retaining walls that Earth Science and Disaster Resilience, No.426, 114pp., 2019 (in employ highly flexible structures such as gabions display Japanese). pronounced deformation in the upper sections, so that the [5] K. Watanabe, Y. Munaf, J. Koseki, M. Tateyama, and K. Kojima, “Behaviors of Several Types of Model Retaining Walls Subjected to estimated slip angle may diverge widely from actual be- Irregular Excitation,” Soils and Foundations, Vol.43, No.5, pp. 13- havior. 27, 2003. [6] S. Okabe, “General Theory on Earth Pressure and Seismic Stability In this study, we raised the soil wedge base and com- of Retaining Wall and Dam,” J. of the Civil Engineering Society, pared the obtained results with experiment results to ex- Vol.10, No.6, pp. 1277-1323, 1924. amine the validity of the position of the base of the slip [7] N. Mononobe and H. Matsuo, “On determination of earth pressure during earthquake,” Proc. of the World Engineering Congress, line in the trial wedge method. When the base height ob- Vol.9, pp. 177-185, 1929. tained from this analysis and the experiment results were [8] M. Ramli, T. J. R. Karasu, and E. T. Dawood, “The stability of gabion walls for earth retaining structures,” Alexandria Engineering compared, it was found that sections of the gabion retain- J., Vol.52, Issue 4, pp. 705-710, 2013. ing wall above the wedge base displayed a pronounced [9] “Section 5-2-5 Evaluation on Sliding, Overturning and Bearing Ca- deformation, or dynamic characteristics that were differ- pacity of Foundation Ground,” Japan Jakago Association, “Guide and Commentary on Gabion Engineering Method,” pp. 95-106, ent from the backfill, such as a phase difference, which in- 2008 (in Japanese). dicated that the setting of the base location was in rough [10] F. Mori, S. Shino, K. Higashihara, and M. Matsumoto, “Earth- quake resistant of castle wall with flexibility (Part 1: Outline of the agreement with the experiment results under the present project),” Proc. of the 39th Japan National Conf. on Geotechnical conditions. Engineering, pp. 1615-1616, 2004 (in Japanese). This result suggests that a trial wedge method can be [11] K. Higashihara, S. Shino, F. Mori, and M. Matsumoto, “Earthquake resistant of castle wall with flexibility (Part 2: Result of centrifuge applied to gabion retaining walls by raising the height of model test),” Proc. of the 39th Japan National Conf. on Geotechni- the wedge base. Meanwhile, issues remain with respect cal Engineering, pp. 1617-1618, 2004 (in Japanese). [12] K. Komanobe, S. Shino, F. Mori, and K. Higashihara, ”Earth- to the method of setting the base according to the de- quake resistant of castle wall with flexibility (Part 3: Comparison formation of the gabion retaining wall, or the application of the analysis and the experiment),” Proc. of the 39th Japan Na- tional Conf. on Geotechnical Engineering, pp. 1619-1620, 2004 (in range. In particular, prior knowledge of the deformation Japanese). of the gabion retaining wall and the accompanying char- [13] Japan Road Association, “Road Construction Works on Soil, Re- acteristics of the backfill are necessary for analysis, so it taining Wall Guidelines,” pp. 97-109, 2012 (in Japanese). [14] T. Ushiro, M. Ogura, H. Tsutsui, and H. Nagayama, “Enhancement will be necessary to develop a knowledge base of analy- of improved trial wedge method for nonlinear slide problems,” Proc. sis conditions, including different types of gabion retain- of Japan Society of Civil Engineers, VI, The Civil Engineering, ing walls and backfill conditions. In this study, we were No.602/VI-40, pp. 151-156, 1998 (in Japanese). [15] H. Nakazawa, T. Hara, D. Suetsugu, K. Kuribayashi, T. Nishi, able to show a possible method for computing the sta- K. Miyoshi, Y. Tadokoro, and K. Usukura, “Full-Scale Shake Ta- bility of gabion retaining walls that displayed reasonable ble Test on Estimation of Earthquake Resistace of a Retaining Wall for Road Using Gabions,” J. of Japan Society of Civil Engi- agreement with the results of a previous full-scale model neers, Ser. A1 (Structural Engineering & Earthquake Engineering experiment, and thus present a methodology for seismic- (SE/EE)), Vol.74, Issue 4, pp. I 441-I 451, 2018 (in Japanese). [16] Department of Roads, Ministry of Physical Planning and Works, resistant design. Government of Nepal, “Standard Specifications for Road and Bridge Works,” ASAD 2058, 2001. [17] D. Suetsugu, H. Matsuo, H. Nakazawa, T. Hara, Y. Tadokoro, K. Kuribayashi, and T. Nishi, “Study on earthquake resistance evalua- Acknowledgements tion method for gabion retaining wall – Part 2 Model tests of gabion Part of this study received funding support under No. 16H04413 structure –,” Proc. of the 72nd Annual Meeting of Japan Society of (General) and No. 16H05746 (Overseas Academic Investigation) Civil Engineers, pp. 483-484, 2017 (in Japanese). [18] D. Suetsugu, T. Hara, H. Nakazawa, Y. Tadokoro, K. Kuribayashi, of the Grant-in-Aid for Scientific Research (B), Japan Society for and T. Nishi, “Evaluation of earthquake resistance of retaining the Promotion of Science. The authors would like to express their wall using gabions by laboratory tests – Part 2 Lateral loading test gratitude to the relevant parties. for model gabion retaining wall –,” Proc. of the 53rd Japan Na- tional Conf. on Geotechnical Engineering, pp. 1797-1798, 2018 (in Japanese). [19] K. Usukura, H. Nakazawa, T. Hara, D. Suetsugu, T. Nishi, K. Kurib- References: ayashi, and Y. Tadokoro, “Full-scale shake table test on evaluation of earthquake resistance gabion retaining wall for road – estima- [1] Department of Urban Development and Building Construction, tion of residual deformation and cracks occurred in the ground be- Ministry of Physical Planning and Works, Government of Nepal, “Mandatory Rules of Thumb Reinforced Concrete Buildings With- hind the retaining wall –,” Proc. of the 13th Annual Meeting of out Masonry Infill,” Nepal National Building Code, NBC 205, Japan Association for Earthquake Engineering, P1-16, 9pp., 2017 30pp., 1994. (in Japanese). [2] T. Hara, H. Nakazawa, D. Suetsugu, K. Kuribayashi, T. Nishi, Y. Tadokoro, K. Miyoshi, and H. Zhang, “Field Survey on Damages of Gabion Structures Caused by the 2015 Nepal Gorkha Earth- quake and Examination of Specific Measures for Earthquake Re- sistance Improvement,” J. of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), Vol.74, Issue 4, pp. I 586-I 597, 2018 (in Japanese). [3] H. Nakazawa, T. Hara, D. Suetsugu, T. Nishi, K. Kuribayashi, K. Miyoshi, and S. Shimomura, “Experimental Evaluation on Earthquake-Resistance of Road Retaining Wall Using Gabion,” J. Disaster Res., Vol.13, No.5, pp. 897-916, 2018. [4] H. Nakazawa, T. Hara, D. Suetsugu, T. Nishi, K. Kuribayashi, C. Zhang, H. Hazarika, K. Miyoshi, S. Shimomura, S. Kimura,

Journal of Disaster Research Vol.14 No.9, 2019 1167 Nakazawa, H. et al.

Name: Name: Hiroshi Nakazawa Tadashi Hara

Afﬁliation: Afﬁliation: Principal Research Fellow, Earthquake Disas- Professor, Center for Disaster Prevention Promo- ter Mitigation Research Division, National Re- tion, Kochi University search Institute for Earth Science and Disaster Resilience (NIED)

Address: Address: 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan Brief Career: Brief Career: 1996- Kiso-Jiban Consultants Co., Ltd. 1999- Engineer, NEWJEC Inc. 2000- Assistant Professor, Tokyo University of Science 2003- Assistant Professor, Chuo University 2007- Project Leader, Port and Airport Research Institute (PARI) 2007- Associate Professor, National Institute of Technology, Wakayama 2012- Fukken Co., Ltd. College 2015- NIED 2010- Associate Professor, Kochi University Selected Publications: 2014- Professor, Kochi University • “Development of earthquake-proof road retaining wall and related Selected Publications: evaluation method,” Impact, Vol.2018, No.1, pp. 67-69, doi: • “Undrained shear strength of granular soils with different particle 10.21820/23987073.2018.67, 2018. gradations,” J. of Geotechnical and Geoenvironmental Engineering, • “Evaluation of in-situ saturation condition for an unsaturation method for Vol.130, Issue 6, pp. 621-629, 2004. liquefaction countermeasures,” The 7th Int. Conf. on Unsaturated Soils • “Investigation and Analysis of a River Dike Damaged During the 2011 (UNSAT2018), Vol.2, pp. 777-782, 2018. East Japan Disaster,” F. Oka et al. (Eds.), “Computer Methods and Recent • “Experimental Evaluation on Earthquake-Resistance of Road Retaining Advances in Geomechanics – Proc. of the 14th Int. Conf. of the Int. Wall Using Gabion,” J. Disaster Res., Vol.13, No.5, pp. 897-916, doi: Association for Computer Methods and Advances in Geomechanics, 10.20965/jdr.2018.p0897, 2018. pp. 1891-1896, CRC Press, 2014. Academic Societies & Scientiﬁc Organizations: • “Resilience Efforts in the Kochi Prefecture in Preparation for the Nankai • Japanese Geotechnical Society (JGS) Trough Earthquake,” J. Disaster Res., Vol.12, No.4, pp. 755-765, 2017. • Japan Society of Civil Engineers (JSCE) Academic Societies & Scientiﬁc Organizations: • Japan Association for Earthquake Engineering (JAEE) • Japan Society of Civil Engineers (JSCE) • Society of Exploration Geophysicists of Japan (SEGJ) • Japanese Geotechnical Society (JGS) • Architectural Institute of Japan (AIJ) • Japan Association for Earthquake Engineering (JAEE) • Geo Risk Society of Japan • Japan Society for Natural Disaster Science (JSNDS) • Japan Geoscience Union (JpGU)

Name: Kazuya Usukura Name: Daisuke Suetsugu Afﬁliation: Chief Engineer, Seismic Engineering and Facil- Afﬁliation: ity Maintenance Division, Eight-Japan Engineer- Department of Civil and Environmental Engi- ing Consultants Inc. (EJEC) neering, Faculty of Engineering, University of Miyazaki

Address: 3-1-21 Tsushima-Kyomachi, Kita-ku, Okayama, Okayama 700-8617, Address: Japan 1-1 Gakuen-Kibanadai-Nishi, Miyazaki, Miyazaki 889-2192, Japan Brief Career: Brief Career: 2014- EJEC 1999- National Defense Academy of Japan Selected Publications: 2005- Institute of Lowland Technology, Saga University • Verification of seismic performance and design of aseismic 2018- Faculty of Science and Engineering, Saga University reinforcement for earth structures and retaining walls 2019- Faculty of Engineering, University of Miyazaki • “Full-scale shake table test on evaluation of earthquake resistance gabion Selected Publications: retaining wall for road – estimation of residual deformation and cracks • “Report of the Damaged Earth Structures due to the 2016 Kumamoto occurred in the ground behind the retaining wall –,” Proc. of the 13th Earthquake,” Geotechnical Engineering Magazine, Vol.65, No.4, Annual Meeting of Japan Association for Earthquake Engineering, pp. 20-23, 2017. pp. 1-16, 2017 (in Japanese). Academic Societies & Scientific Organizations: Academic Societies & Scientific Organizations: • Japan Society of Civil Engineers (JSCE) • Japanese Geotechnical Society (JGS) • Japanese Geotechnical Society (JGS) • Japan Society of Civil Engineers (JSCE) • International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE)

1168 Journal of Disaster Research Vol.14 No.9, 2019 Problems in Earthquake Resistance Evaluation of Gabion Retaining Wall Based on Shake Table Test with Full-Scale Model

Name: Name: Kentaro Kuribayashi Shun Kimura

Afﬁliation: Afﬁliation: Chief Engineer, Seismic Engineering and Facil- Engineer, International Department, Eight-Japan ity Maintenance Division, Eight-Japan Engineer- Engineering Consultants Inc. (EJEC) ing Consultants Inc. (EJEC)

Address: Address: 3-1-21 Tsushima-Kyomachi, Kita-ku, Okayama, Okayama 700-8617, 5-33-11 Honcho, Nakano, Tokyo 164-8601, Japan Japan Brief Career: Brief Career: 2012- EJEC 2009- EJEC Selected Publications: Selected Publications: • Repair design, diagnosis and maintenance planning for bridges • Verification of seismic performance and design of aseismic • “Evaluation on earthquake resistance for retaining wall using gabions by reinforcement for earth structures and retaining walls full scale shaking table tests. Part 1. Test outline,” The 53rd Japan National • “Damage survey on gabion structures in the 2015 Nepal Gorkha Conf. on Geotechnical Engineering, August 2018. Earthquake,” The 14th Int. Symp. on Geo-Disaster Reduction, 2pp., 2016. • “An issue of seismic structure and construction regarding gabion Academic Societies & Scientific Organizations: retaining wall in rural area of Nepal,” The 7th Asia Conf. on Earthquake • Japanese Geotechnical Society (JGS) Engineering, 2018. • Japan Society of Civil Engineers (JSCE) Academic Societies & Scientific Organizations: • Japanese Geotechnical Society (JGS)

Name: Tsuyoshi Nishi Name: Shoji Shimomura Afﬁliation: Director, Construction Project Consultants Inc. Afﬁliation: Manager, Daioh Shinyo Co., Ltd.

Address: 4-40-11 Takadanobaba, Shinjuku, Tokyo 169-0075, Japan Address: Brief Career: 1625-2 Niida, Kochi, Kochi 781-0112, Japan 1984- Construction Project Consultants Inc. (Renamed company name in Brief Career: 2009) 1984- Daioh Construction Co., Ltd. (currently Daioh Shinyo Co., Ltd.) Selected Publications: Academic Societies & Scientiﬁc Organizations: • “Evaluation on earthquake resistance for retaining wall using gabions by • Japan Society of Civil Engineers (JSCE) full scale shaking table tests, Part 3. Evaluation on stability of wall by • Japanese Geotechnical Society (JGS) FEM analysis,” 53rd Japan National Conf. on Geotechnical Engineering, • Japan Concrete Institute (JCI) pp. 1811-1812, 2018 (in Japanese). Academic Societies & Scientiﬁc Organizations: • Japan Society of Civil Engineers (JSCE) • Japanese Geotechnical Society (JGS)

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