Q_3黄土残余变形对孔隙压力控制作用试验研究

Controlling influence of residual deformation on void pressure of Q_3 loess based on laboratory testing analysis

土体残余变形与孔隙压力的作用关系,是理解土体受荷力学响应行为的重要问题。利用室内静(动)三轴试验,获取天然黄土受载后的轴向残余变形、体积残余变形、孔隙气(水)压力变化的时程数据,研究残余变形和孔隙压力的对应关系,厘定残余变形对孔隙压力的控制作用。结果表明:轴向残余变形描述孔隙气(水)压力的响应过程及绝对量值时,具有局限性;孔隙气(水)压力的响应过程及成因具有一致性,与初始应力条件及加载形式无关;孔隙水压力的绝对量值对围压具有强依赖性,体积残余应变相同时水体对孔隙水压力绝对量值的贡献是气体对孔隙气压力的10倍。孔隙压力的响应过程及成因,取决于固相颗粒介质和气、水相介质之间的作用机理;其绝对量值,决定于气、水相介质的渗透性、压缩性等固有特性。

The relationship between residual deformation and void pressure is the key to understand the soil dynamic behavior. Here,through acquiring time-history data of vertical residual strain,bulk residual strain and void pressure of natural loess,we analyzed the quantitative relationship between residual deformation and void pressure. The testing data disclose that the vertical residual strain is not enough to describe the variety of responding process and absolute value of void pressure at different conditions of saturation level and external loading. Meanwhile,the process and cause of void air / water pressure has a high degree of uniformity,which could not be influenced by initial stress conditions or loadings. Moreover,the absolute value of void water pressure strongly depends on the confining pressure whereas the void air pressure is contrary. While the bulk residual strain is the same,the contribution of water phase to the absolute value of void pressure is 10 times as much as the air phase. In brief,the uniformity of responding process and cause of void air / water pressure depends upon the interaction mechanism between solid particles and air / water media,but the absolute value of void pressure depends upon the permeability and compres-sibility of air / water within the soil mass.