Local site conditions and hydromechanical effects in service life of cantilever retaining walls

Abstract

The present study has two objectives for the design of cantilever walls based on the local site conditions: i) estimating the minimum foundation width in the seismic loading condition and ii) determining the critical water level, which causes wall failure, for the design of an effective drainage system. Therefore, cantilever retaining walls are designed according to different design considerations such as stem height (H = 2.5, 4, 6 m), local soil class (ZC, ZD, ZE), and seismic characteristics of ground (PGA = 0.095–0.687 and kh = 0.057–0.403). Stability analyses (bearing capacity, allowable eccentricity, sliding, overturn, overall stability, and settlement) were performed using the limit equilibrium method. Static and dynamic earth thrusts were determined using the Coulomb and Mononobe-Okabe methods, respectively. Analysis results show that local soil class is a more effective parameter than PGA in the seismic design of cantilever walls. Regression equations (R2 > 0.97) are proposed to estimate minimum foundation width (B) easily. Moreover, the critical water height decreases to one-fifth of the wall height, especially in regions with low earthquake risk (PGA < 0.2). Regression equations (R2 > 0.98) are proposed to find critical water height. In the design of the drainage system, inclined perforated pipes should be connected to horizontal ones and continued up to the critical water height on the interface layer between the backfill and natural ground.