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土的初始剪切模量G_0是地震、爆破响应中一个非常重要的土动力学参数,对预测地表沉降、土工建筑物周围土体变形等具有重要作用。黄土在中国及世界各地分布广泛,且现场常处于非饱和状态。对非饱和黄土的压实试样进行了吸力控制的共振柱试验以及压汞试验,研究非饱和黄土初始剪切模量G_0与孔径分布的关系。试验表明:干湿循环过程中,试样的G_0随吸力的增大而增大,再随吸力的减小而减小。主要原因是试样内孔隙密度最大的孔径大小随吸力的增大而减小,试样内大孔隙减少,小孔隙增多,导致毛细水所占比例增加,土颗粒接触更加紧密。同一吸力作用下,湿润段试样的小孔隙比例比干燥段大,故毛细水作用更显著,从而湿润段试样的G_0大于干燥段。
The initial shear modulus of soil G_0 is a very important soil dynamic parameter in earthquake and blasting response. It plays an important role in predicting ground settlement and deformation of soil around the geotechnical structures. Loess is widely distributed in China and around the world, and the site is often in a non-saturated state. Resonant column test and mercury injection test were conducted on the compacted sample of unsaturated loess to study the relationship between initial shear modulus G_0 and pore size distribution of unsaturated loess. Experiments show that: during the wet-dry cycle, the G_0 of the sample increases with the increase of suction, and then decreases with the decrease of suction. The main reason is that the pore size with the largest pore density in the sample decreases with the increase of the suction force. The large pores in the sample decrease and the small pores increase, which leads to the increase of the proportion of capillary water and the closer contact of soil particles. Under the same suction, the small pore ratio of the wetted section is larger than that of the dry section, so capillary water effect is more significant, so the G_0 of the wetted section is larger than the dry section.