Necessity of Geotechnical Data Base and of Reliable Technical Title Committees for the Civil Engineering Projects Author(s) Adachi, Toshihisa Proceeding of TC302 Symposium Osaka 2011 : International Symposium on Backwards Problem in Geotechnical Citation Engineering and Monitoring of Geo-Construction (2011): 194- 202 Issue Date 2011 URL http://hdl.handle.net/2433/173828 Right Type Article Textversion publisher Kyoto University International Symposium on Backward Problems in Geotechnical Engineering TC302-Osaka 2011 Necessity of Geotechnical Data Base and of Reliable Technical Committees for the Civil Engineering Projects T. Adachi Geo-Research Institute, Osaka, Japan ABSTRACT: In order to safely and soundly construct any civil engineering infrastructure and to predict the liquefaction potential as well as the seismic intensity, it is very important to have a reliable geotechnical data base and also to constitute an effective scientific and technical committee. At first, this paper describes the out- line of geotechnical database, “Kansai Geo-Informatics Database (GI-base)”, that was created by a consortium of geotechnical engineers/researchers and their affiliated organizations in Kansai region of Japan; the KG-NET (Kansai Geo-informatics Net work). Then, it emphasizes that the geotechnical engineers must have the knowledge of subsurface structure in addition to that of soil properties. Finally, it introduces the case history of a successfully disbanded technical committee for the Nakanoshima railway line (subway) construction project which consisted of members not only from universities, owner and administrative organizations, but also from contractors. The committee greatly contributed to the successful completion of the Nakanoshima line. 1 INTRODUCTON Secondary, it stresses the importance of knowledge of subsurface structure by showing a In this paper, at first, the usefulness of GI-base and case history. Finally, a technical committee, which its historical development are represented. The his- was banded to support the construction of the tory of geo-informatics research in which geology Nakanoshima Railway Line, is discussed. In the and geotechnics have been closely collaborated is history, the railway and ground transportation net- one of the key factors for the successful achieve- works have been taking over the role of the river ment of GI-base. The Kansai region is the second transportation in Osaka. Now, Nakanoshima Island largest area where old capitals of Japan such as is the area of increasing high-density land use, Osaka, Nara, and Kyoto are located. These cities therefore the improvement of the transportation have been developed mainly on low, flat and allu- links is required. Nakanoshima Line is in the sym- vial plains. In addition to Osaka, Kobe and many bolic island of water metropolis of Osaka, and it other cities are developed in the Osaka Plains and will not only contribute to the further economic along the coast of the Osaka Bay where soft development but also provide a direct link with the grounds are widely spread. Thus the development central and northern area of Kyoto city via Keihan of these cities required careful site investigations Main Line. Furthermore, Nakanoshima Line will with a very large number of borehole studies to contribute to improvement of the transportation construct much of needed infrastructures, such as network in Kansai region. highways, railways, lifelines, and airport construc- Since the construction had to be done under tions, as well as to establish disaster prevention very severe conditions, not only geotechnical but countermeasures. also surrounding environmental conditions, it was needed to establish a technical committee, which 194 International Symposium on Backward Problems in Geotechnical Engineering TC302-Osaka 2011 consisted of both academic researchers and practi- geotechnical and geological features of the Osaka cal engineers. The committee greatly contributed Basin by collecting significant amounts of to the successful completion of the Nakanoshima Line. 2005~ KG-NET Kansai Geo-informatics 2. GI-BASE AND ITS HISTORY Network Kansai 2005 (GI-base) 2003~ 2005 2.1 Outline GI-Base Council Kansai Geo-informatics 2000 1998~ 2003 Research Council of The Geo-Information Database in Kansai (GI- Geotechnical Information on OB Osaka Kansai 1995 1995~2003 Geo-Database Information base) was constructed by gathering a very large Bay Inland Committee of Kansai amount of borehole investigation data obtained in 1990 many projects of urban construction in Kansai re- 1989~1994 Research Committee on Utilizing of Underground Space & Research Committee on Structure and Properties of gion, such as the construction of manmade islands, 1985 Deep Underground in Kansai (JGS Kansai Branch) subways, lifeline, etc. 1991~1995 Research Committee on Geotechnical Information of OBSD Fig. 1 shows the locations of more than 48,000 1980 1984~1991 Research Committee on Seabed Deposit of Osaka Bay (JGS boring data, which have been collected and digit- Kansai Branch) ized. Through geological and geotechnical inter- pretations, GI-base has been developed and updat- Fig. 2 Historical developments of GI-base and KG- ed. Cross-section view of the required underground NET can easily be drawn on personal computers togeth- er with various soil properties such as classifica- borehole data, and there have been publications of tion, gradation, the thickness of each layer, ground “Osaka Ground” (a collection of soil boring logs) in 1970, and “A New version of Osaka Ground” in water level, N SPT values and so on. The history of geo-informatics research in which geology and ge- 1987, although no digital borehole database was otechnics have been closely collaborated is one of created. the key factors for the successful achievement of Borehole investigations for the Kansai Interna- GI-base. tional Airport and Phoenix Project (landfills for waste disposals) have started one after another in the Osaka Bay around 1980. Extensive investiga- tions of the Osaka Bay seabed were necessary for the waterfront development, and archiving of data in digital form by GRI became routine with the de- velopment of computers. The Research Committee Kyoto Shiga on Seabed Deposit of Osaka Bay (1984-1991, Chairperson, Prof. K. Akai) was established first by the Kansai Branch of JGS. This activity was succeeded to the Research Committee on Osaka Kobe Bay Geo-Informatics and Utilization (1991-1995, Osaka Nara Prof. T. Matsui), and the Research Council of Osa- ka Bay Geo-Informatics (1995-2003). Through Osaka Bay these research activities, “Geo-Informatics Data- bases in Osaka Bay Area” (GI-base OB) was con- structed. On the other hand, the Research Committee on Wakayama Underground Space Utilization (1989-1994, Chairperson, Prof. T. Adachi) was established, and Fig. 1 Distribution of boreholes in GI-base this committee dealt mainly with public sector’s infrastructure to utilize deep underground spaces in 2.2 Historical Developments of KG-NET the large cities (Osaka, Kobe, and Kyoto). This committee worked together with the Research Fig. 2 shows the chronology of how the KG-NET Committee on Structure and Properties of Deep was developed from the starting organization of Underground in Kansai Branch of JGS (1989- the Research Committee on Sea-bed Deposit of 1992). This activity was succeeded to the Geo- Osaka Bay (1984-1991). Before the geotechnical Informatics Committee of Kansai (1995-2003). researches by this committee, there have been sev- During these research activities, “Geo-Informatics eral research groups under the Kansai Branch of Databases in Kansai Inland” (GI-base K) was con- Japanese Geotechnical Society (JGS) studying the structed. 195 International Symposium on Backward Problems in Geotechnical Engineering TC302-Osaka 2011 These two databases were integrated into a sin- cene clay in this region is well known as sensitive gle system in 2003, and the whole data was man- clay. aged under an organization of the Council of Kan- In the practice of earthquake disaster prevention sai Geo-informatics (2003-2005). Further in 2005, and mitigation for a wide area, estimate of the it is recognized to form “Kansai Geo-Informatics damage that will be caused by the earthquake of Network (KG-NET Chaired by )”. target area is generally performed. And then, local governments draw up the regional plan for disaster 2.3 Geotechnical Fragility Mapping in Terms of prevention based on the information of volume and Seismic Intensity Due to Expected Uemachi Earth- locations of damages due to earthquake. The pre- quake diction of earthquake behavior, such as seismic in- tensity, liquefaction occurrence, and others, is very A representative cross-sectional view of subsurface vital, as its results become the basis of evaluating ground for Osaka Plain is shown in Fig. 3. The se- earthquake damages. lected line is the one along the subway Chuo Line As previously mentioned, GI-base could be a from the coast of Osaka Bay to Ikoma Mountain. versatile tool to provide necessary input of under- Uemachi Upland is located in the heart of Osaka ground geometry as well as dynamic properties of where all strata are tilting by the prevalence of the strata. In the practical sense, the regional distri- flexure structure developed by the tectonic move- bution of hazardous area against high seismic in- ment of the Uemachi Fault. tensity and liquefaction due to earthquake can W E do E Yo v . Re W Osaka Plain Osaka Bay Fig. 3 Cross-sectional view of subsurface ground for Osaka Plain On the west side of Osaka, the thick Holocene ma- provide very important and useful information for rine clay (Ma 13) layer exists underlain by the disaster mitigation. Pleistocene gravel layer and the alternating Pleis- Let us pay attention to the distribution of the up- tocene deposits. The strata are rather stable and per Holocene sand and clay layers in Osaka Plain horizontal deposited. On the eastern part of Osaka, and the surrounding area because those layers in- the basin structure can be seen between the Uema- tensify seismic intensity and can be fragile for liq- chi Upland and the Ikoma Mountains.