四向振动空心圆柱扭剪仪模拟主应力轴旋转应力路径能力分析

主应力轴旋转对土体的动力特性有着显著影响。利用GDS动态空心圆柱扭剪仪（HCA）能够实现内围压、外围压、轴力和扭矩四向动态加载的功能，提出了3种主应力方向变化的应力路径加载方式，分析了3种应力路径在实际工程中的应用，并进行了试验验证。当四向动载根据推导的波形函数加载时，可以实现：① 平均主应力p、中主应力系数b和偏应力q保持恒定，主应力轴循环旋转的应力路径；② 平均应力p和中主应力系数b保持不变，偏应力q循环变化，而主应力方向角? = 90°突变的应力路径；③ 平均主应力p、中主应力系数b保持不变，偏应力q、主应力方向角α连续变化的应力路径。应力路径①为模拟海洋波浪荷载作用下的应力路径试验提供了理论依据，应力路径②可用于模拟不同方向地震荷载的作用，应力路径③可以模拟波浪荷载作用下桩周土体的应力路径以及交通荷载作用下的应力路径。

Analysis of capabilities of stress paths of HCA to simulate principal stress rotation under four-direction dynamic loads

The principal stress rotation has a significantly influence on the dynamic characteristics of soil. According to the function that GDS dynamic hollow cylinder torsional apparatus(HCA) can apply four dynamic loads, namely inner pressure, outer pressure, axial load and torque, the loading mode is put forward for three possible stress paths which are applied in practical engineering with the principal stress rotating, and three kinds of tests are conducted to confirm that the stress paths can be realized in the HCA. When the four dynamic loads meet some corresponding requirements, the following stress paths can be realized: ① When the mean principal stress p, the intermediate stress ratio b and deviatoric stress q are kept constant. ② the cyclic deviatoric stress q is applied when the mutation of α, i.e. the rotation of major principal stress relative to the vertical direction, is 90°. ③ When the cyclic deviatoric stress q is applied with the principal stress continue rotating. In addition, the first path provided theoretical foundation for experiment of simulating the stress paths under wave loading; the second path can be applied to simulate the dynamic characteristics of soils subjected to earthquake load; and the third path can be used to simulate the stress paths of soil around the pile under wind and wave loads and the stress paths under traffic loads.