基坑地连墙后有限土受力特性试验研究

为了研究城市基坑施工地连墙后有限宽度无黏性土的破坏模式及其压力分布特征,依托可模拟不同复杂工况的试验模型箱,开展地连墙平动模式下的主动土压力模型试验。通过数码相机记录填土随地连墙平行移动过程中的破坏全过程,采用颗粒图像测速技术分析有限宽度无黏性填土的变形特性和有限填土的破坏形式,并将测得的主动土压力与理论解进行对比。试验结果表明:有限填土几何条件的变化将影响填土的破坏模式,两侧边界的限制是地连墙平动模式下有限填土内部产生多道滑动面的主要原因,滑动面以曲面形式呈现;主动土压力值随填土宽高比的增大而增大,半无限土体状态下,主动土压力值接近库伦土压力值;第一个“反射点”随自然坡面倾角的增大而上移;随着有限填土区域的增大,主动土压力值也逐渐增大。

Experimental Analysis on Mechanical Characteristics of Narrow Backfill behind Foundation Pit Diaphragm Wall

In order to study the failure mode and pressure distribution characteristics of narrow cohesionless backfill, relying on the test model box that can simulate different complex working conditions, the active earth pressure model tests in translational mode are carried out. The process of destruction during the parallel movement of the backfill with the retaining wall was recorded by a digital camera. Particle image velocimetry technology was used to analyze the deformation characteristics of narrow cohesionless backfill and the failure form. The measured active earth pressure was compared with the theoretical solution. The test results show that the change of the geometric conditions of the finite backfill affects the failure mode of the backfill. The limitation of the boundaries on both sides is the main reason for the multiple sliding surfaces inside narrow backfill under the translational mode. The sliding surfaces are presented as curved surfaces. The active earth pressure value increases with the increase of aspect ratio. Under the semi-infinite soil state, the active earth pressure value is close to the Coulomb earth pressure. The first "reflection point" moves up with the increase in the inclination of the retaining wall, and also moves up with the increase in the inclination of the natural slope. As the limited backfill area increases, the active earth pressure also increases.