排灌水引起砂土层沉降的宏细观试验分析

Macro-meso test analysis of sand subsidence caused by withdrawing and recharging water

利用自行设计的砂土排灌水试验装置,分析地下水排灌引起的砂样宏观竖向变形及细观移动.通过试验测量了反复排水和回灌时砂样的竖向变形,采集了局部土颗粒图片并采用Geo DIP(geotechnical digital image processing)软件对颗粒位移及定向性进行了分析.结果表明:在砂样排灌水的初期阶段,砂样的结构发生了明显重组,砂样沉降不仅发生在排水时,而且回灌时砂样沉降继续增加,砂样产生了较大的、不可恢复的塑性和黏性变形;砂样结构达到相对稳定后,排水时产生的竖向变形变小,而回灌时砂样发生较大的回弹;土颗粒的长轴方向在第一次排水时转动不大,在第三次排水时转动较大,而在第六次排水时转动又变得不明显.试验结果可为控制地面沉降提供参考.

Using a self-designed apparatus for sand sample withdrawing and recharging water, macro vertical deformation of sand sample sand meso move of a sand particle induced by withdrawing and recharging water were analyzed. Vertical deformation of sand samples was measured in the test. Local soil particle pictures were taken and displacements and orientations of the soil particles were investigated with a geotechnical digital image processing（Geo DIP） software. Initially the sand was restructured. The sand settlement arose during withdrawing water and became larger during water recharging as a result of visco-elasto-plastic deformation of the sand sample. After the sand sample became stable,the settlement value became smaller than the initial stage during withdrawing water. The resilience value became larger than the initial stage during recharging water. Rotation of soil particles was small during the first withdrawal, became considerably large in the third withdrawal, and then became negligible during the sixth withdrawal. This work provides a reference for controlling city land subsidence.