Influence of Corner Effect in Cobble Stratum Deep Foundation Pit on Deformation of Adjacent Buildings

Abstract

[Objective] Under the influence of corner effect in deep foundation pit, significant differences in deformation occur in the retaining structure at the pit corners. Buildings along various directions of the foundation pit experience varying settlement values. The corner effect is particularly pronounced in cobble stratum, posing a high risk of structural damage. Therefore, it is necessary to investigate the impact law of corner effect in deep foundation pit in cobble stratum on the deformation of adjacent buildings. [Method] Taking Guangxi University Station of Nanning Rail Transit Line 5 as example, the influence range of the corner effect is studied through the analysis of actual monitoring data. A three-dimensional finite element calculation model is established using Plaxis software to analyze the deformation law of the diaphragm wall and adjacent buildings within the corner effect range. [Result & Conclusion] The corner effect range in cobble stratum is determined to be 2.8H (H as the excavation depth). The corner effect results in significantly greater horizontal displacement of foundation pit mid-section diaphragm wall compared to the corner, with a maximum increase of 82.2%. When the distance between buildings and the pit corner is≥1.5H, the restraining action of pit corner effect on building deformation weakens. With variations in the distance between buildings and the pit corner or edge, the uneven settlement values and tilt rates of building longitudinal walls show a steep parabolic change trend in the vertical direction to the foundation pit edge, while in the parallel direction to the foundation pit edge, the curve changes of the uneven settlement and tilt rates of building longitudinal walls can be divided into a parabolic trend with steep decline, convex, and concave patterns.

Keywords

• metro
• cobble stratum
• deep foundation pit
• corner effect