宽级配砾质土作为GCls防渗垫保护层的抗剪强度试验研究

水化后的土工织物黏土垫层(GCls)是良好的复合防渗材料,但同时表现出较低的抗剪强度特性。为改善水化后的GCls抗剪强度低的缺陷,拟采用取自天然并经人工调配的宽级配砾质土料代替黏土作为GCls防渗垫的保护层,共同构成复合防渗系统。文中利用TGH直剪摩擦拉伸仪对筛选出的宽级配砾质土及其与不同水化条件下的GCL接触面进行了试验研究,得到宽级配砾质土样及其与质量含水率分别为50%和完全水化的GCL接触面的抗剪强度试验数据并进行了整理分析。结果显示,宽级配砾质土样的抗剪强度大于其与不同水化条件下的GCL接触面的抗剪强度,且宽级配砾质土与GCL接触面的抗剪强度随GCL含水率的增加而减小。因此,可以根据外荷载作用下土中应力会发生扩散的原理,利用抗剪强度高和压缩性低的砾质土来承担部分甚至全部荷载,以弥补水化后的GCls抗剪强度低的缺陷。

SHEAR STRENGTH TESTS OF COMPACTED GRAVEL SOILS FOR GCls PROTECTIVE LAYER

Hydrated geosynthetic clay liners(GCls) are the excellence anti-seepage material. But they exhibit extremely low shear strength at the same time. To improved the disadvantage, a protector that adequately backfill over the GCL is set so as to consist of composite liners system. The artificially graded gravel soils are taken from natural sediment. The compacted gravel soils instead of clay are as a protective layer of GCls liner. The compacted gravel soils are selected according to the requirement of the code. They are put into the direct shear apparatus under the GCL with a hydration degree of, respectively, 50% and complete saturation. The direct shear friction tensile tester(TGH) is used in this paper. The experiments are performed. The results show that the shear strength of compacted gravel soils is far more than the contact surfaces that are consisted of compacted gravel soils with hydrated GCL.The shear strength of the contact surfaces is decreasing with the increasing of GCls' moisture content. So it is effective to release the pressure of GCls with the help from high bearing capacity of wide grading gravel soils according to the principle of stress diffusion in soil.