Analysis of Gabion Retaining Wall for a Site at Bahria Town Rawalpindi using Analytically and Numerical Modeling with Plaxis 2D

Abstract

The retaining walls resist the lateral loads and maintain the different levels on both sides of the wall. From the beginning, civil engineers have put efforts into constructing and design a variety of retaining walls for time and cost-saving. For example, the simple classical gravity retaining walls are converted into the reinforced concrete-type retaining walls. However, one of the most effective but least studied types of retaining walls is the gabion wall. Gabion walls are gaining tremendous fame due to their aesthetic looks, durability, and cost-effectiveness. Due to the lack of research on this retaining wall, problems occur and eventually lead to failure. Different cases have been selected in this study for analytical and numerical modeling analysis. Out of four selected cases, One is locally reported while the others are taken from past literature. The local one was reported for bulging in Bahria town Rawalpindi Pakistan, and the wall was constructed for the lawn area of a residential building comprised of area 25mx30m. A complete site investigation was performed to find out the possible causes of failure. In the preliminary survey, no erosion, corrosion, or wire breaks were found. The reason for bulging was caused due to weak joint formation, and joints were not staggered. In Geotechnical investigation unit weight of gabions was around 20KN/m3, which is less than the previously assumed unit weight of 23KN/m3. The analytical analysis shows that structure is safe externally against sliding, overturning, and base pressure with the feasible FOS. The numerical modeling shows that structure is marginally safe with a Factor of safety 1.073 and the horizontal and vertical displacements are not up to the allowable limits of 0.15m. The other possible reasons for failure in numerical modeling are the overstresses of soils at the structure's toe, i.e., 219KN/m2. Modifications are made to the original design cross-section and analyzed again on PLAXIS. With a modification of the gabion wall, Total displacements are reduced 75 percent, and the factor of safety increases 30 percent. 200mm concrete at the bottom reduces the displacements up to 50 percent, and the factor of safety increases 10 percent. Providing concrete at the foundation decreases the risk of differential settlement and equally distributes stresses to the ground. It is recommended to design the gabion wall as a stepped face with 200 mm concrete at the bottom.