Performance of batter pile walls in deep excavation: Laboratory test and numerical analysis

With the increasing excavation depth of foundation pits, the traditional cantilever vertical pile wall cannot meet the requirements of ground settlement and lateral deflection, and excess deformations would cause not only retaining system failures but also damage of adjoining structures. Thus, a batter pile wall was employed, but its behavior has not been fully demonstrated. To evaluate the performance of the batter pile wall, the laboratory model test was conducted on the basis of scaling law, and the numerical simulation was employed for the validation of experimental results. The results indicated the following conclusions: (1) The bearing capacity of batter pile wall is quite larger than that of the vertical one. The inclination degree should be in an appropriate range, otherwise, the efficiency of batter pile may decrease or leading to occupation of the precious excavation space. The recommended inclination angle is 9 degrees to 15 degrees. (2) With the increase in inclination angle, the pile shaft deflection, ground settlement and bending moment decrease significantly. The influencing distance of excavation is approximately 1.2 times of the dredging depth. (3) The cross section size, penetration depth and shear strength of soil would influence the response of batter pile wall, thus a careful optimazition process is necessary. For insurance purposes, the slender ratios are recommended to be set less than 40 and the penetration ratio is suggested to be larger than 0.4 to minimize the lateral deflection.