为探究富水砂性地层中地墙渗漏诱发地层塌陷灾害的细观机制，依托南通某深基坑地墙渗漏事故实例，采用CFD-DEM流-固耦合模拟方法，对渗漏诱发的地层塌陷灾害演化规律进行细观分析，并探究不同渗漏深度的影响及灾害防治措施。研究结果表明： 1）渗漏条件下，地层受影响区域边界与水平面夹角近似为（45°+φ/2），由渗漏导致的地表沉降增量在地墙后1HL（HL为渗漏中心埋深）范围内量值较大，发展较快； 2）渗漏过程中，地层内部的空洞发展经历了生成、扩展、坍塌3阶段，空洞的坍塌伴随着地表沉降加速发展； 3）相较于无渗漏情况，地墙渗漏会引起渗漏中心附近主动水土压力突增5.7~8.5倍，其中，当渗漏发生在开挖面附近及以上时水土合力增幅较大。富水砂性地层中地墙渗漏会引发地墙结构断裂、坑外地表突沉以及踢脚破坏风险。
A case study is conducted on a foundation pit in
Nantong, China, to investigate the mesomechanism of ground collapse
induced by the leaking of underground diaphragm wall in waterrich sandy strata. In addition, the evolution law of the ground
collapse is analyzed by computational fluid dynamicsdiscrete
element method and related countermeasures are discussed. The following results
are obtained: (1) The included angle between the boundary line of the
influenced zone and the horizontal line is approximately (45°+〖WT〗φ/2)〖WT５《TNR》〗 in the
case of an underground diaphragm wall. The value and growth rate of ground
collapse increment induced by the leakage are large and within〖WT〗 1HL (HL〖WT５《TNR》〗=leakage
depth) behind the underground diaphragm wall. (2) During the leak, the ground
cavity undergoes generation, expansion, and collapse stages and rapidly
collapses with ground settlement. (3) Active earth and water pressure near the
leaking point increases by 5.7 to 8.5 times compared to that observed in the
model with no leakage. This increase is large when leakage occurs at or above
the excavation surface. Underground diaphragm wall leaking may lead to
structural cracks, abrupt ground subsidence outside the pit, and the kicking
damage of the retaining wall.
