CASE HISTORY Rev: 00, Issue Date.14.12.08 GABION WALLS FOR KSTP UPGRADATION ,INDIA ENVIENVIRONMENTAL/ HYDRAULIC & EROSION CONTROL/ SLOPE PROTECTION Product: Gabion Walls

Problem The Kerala State Transport Project (KSTP) aimed to improve traffic flow and road safety on Kerala State’s primary road network and to strengthen the institutional and financial capacity of Kerala’s key trans- port agencies. This was a world bank aided Project. The main aim of this project was up gradation of State Highways, providing periodic maintenance to Highways and District Roads and also minor mitigation measures.

The stretch between Alleppey and Changanacheri had to be widened as well as the embankments had to be protected. The soil at this site was soft clay with low friction angle. Since Kerala receives high amount of rainfall ,the proposed retaining structures were meant to give protection of the embankment from floods and also to provide good drainage.

In the widening process, the stretch along to Thiru- valla in the and some stretches in Ottappalam also needed retention. The in-situ soil along these stretches were laterite which is also soft and unstable during monsoon season. Lateritic soil, when it is hardened, furnish a good bearing stratum. The hardened crust has a low compressibility and therefore settlement may be negli- gible. However, the strength of laterite may decrease with increasing depth. Another significant criteria of laterite is the loss of strength at the time of monsoon in presence of water. Photo 1 .Site conditions before construction of A.C.Road

Solution For all the above stretches, the Consultants LBI had proposed three alternatives such as GabionWalls, Random Rubble Walls and Con- crete Walls. Among the three Gabion Walls were selected because of its flexibility and free draining nature. The random rubble wall and concrete wall are ruled out as they are rigid ,exert too much pressure at the base and necessitate the requirement of separate drainage ar- rangements.

Client name: KERALA STATE TRANSPORT PROJECT Main contractor name: PATI-BEL JV, ROAD BUILDERS Consultant: LOUIS BERGER INTERNATIONAL, RITES BECA WILBURSMITH Product used: 100 TONS OF GABIONS Construction info Construction date: DEC 2004 Construction info: OCT 2006 Photo 2. Photograph showing the ongoing construction at A.C.Road Photo 3,4.Construction proceeds at A.C. Road and M.C.Road respectively

Project section drawing Photo 5. Ongoing Construction at M.C.Road Photo 6. Completed Structure of A.C.Road

Alappuzha Changanasseri Road The entire scope of work for this Project can be summarized as: 1.Retaining earth for embankment of varying heights. 2. Providing good drainage at the rear end . 3 The embankment should be capable of withstanding vehicular load

The solution provided shall be briefed as follows 1)The embankment retention was done by using Gabions of heights ranging from 1m to 6m. 2) Since the foundation soil had poor frictional properties, a foundation improvement scheme was suggested. The proposal was to re- place the existing foundation soil for a depth of 150mm from ground level with soil having frictional properties greater than 25 degrees.

Main Central Road & Ottappalam

In the above stretches also, the solution was adopted in a similar manner. There was no requirement for any foundation replacement since the available soil was laterite. Since laterite often acts as a water-bearing stratum, provision for good drainage was made for these stretches also.

Construction aspects Date: Feb 2001

A.C.Road

When the actual construction was done, the existing foundation soil was replaced by compacted stones and boulders. So, the factor of safety increased considerably. In this Project ,some special size Gabions were made for reducing the overall size of the structure. They were supplied from Maccaferri Brazil and Nepal. Since the structure had to withstand high corrosive environment, Zn+PVC coated Gabions with wire diameter 2.7/3.7mm and mesh size 10x12 were used.

The construction was done by a joint venture between a Malaysian Company PATI and the Indian Company Bhageeratha Engineering Company Limited (BEL)

M.C.Road

Zinc Coated Gabions with wire diameter 3mm and mesh size 10x12 were used .The actual construction at this site was done by Road Builders. The speed of construction was quite good.

Completed Structure of A.C.Road

Completed Structure of M.C.Road

Maccaferri Environmental Solutions Pvt. Ltd. 1003,10th Floor,Casablanca,Plot No.45,Sector-11,CBD Belapur,Navi Mumbai-400614 Tel. 91-22– 27580475/27565451/ 27565906/27580931/ 27580932 - Fax (022) 27580488 E-mail: [email protected], [email protected] - Web site: www.maccaferri.com