泥浆在地层中的渗透特性试验研究

保持开挖孔(槽)的稳定性是泥浆在地下连续墙、钻孔灌注桩及泥水盾构工法等工程中最重要的作用,是通过泥浆在地层表面形成泥皮,使得泥浆压力平衡地层的土水压力实现的。其中,泥皮的形成是泥浆在地层中的渗透问题。为了探讨泥浆在地层中的渗透规律,采用多组性质不同的泥浆在多种渗透性不同的地层中开展泥浆在地层中的渗透试验,系统地展示了泥浆在地层中不同的渗透现象。渗透完成后泥浆颗粒在地层表面的堆积形态可以分为:泥皮型、泥皮+渗透带型、无泥皮或渗透带3种类型,并且泥浆在地层中的渗透曲线的类型与泥浆颗粒在地层表面的堆积形态的类型有一定的对应关系。泥浆在地层中的渗透试验过程中渗透流量的大小,不仅可以反映泥浆的渗透类型,还可以作为判断是否形成泥皮的标准。

Experimental study of law of slurry infiltration in strata

Supporting the excavation face is the most important role for slurry in the field of engineering, such as diaphragm walls, bored piles, and slurry shield tunneling. To achieve the function, a filter cake has to be formed on the soil, and the soil and pore water pressure have to be counteracted by slurry pressure. And the essence of filter cake formation is that the slurry infiltrates in the stratum. To reveal the phenomena and laws of slurry infiltrating into the soils, a series of slurry infiltration tests is carried out on sand samples with different permeabilities. Based on the test results, three typical seepage curves are discovered, and the shapes of slurry particles accumulated on the ground surface are also divided into three types: filter cake, filter cake with an infiltrated zone, and only an infiltrated zone without filter cake. Meanwhile, a corresponding relationship is discovered between the types of slurry seepage curves and the shapes of slurry particles accumulated on the surface. In addition, the seepage discharge during slurry infiltrating into the sand reflects the type of slurry infiltration. And it can be used as a criterion to determine whether a filter cake is formed on the surface.