主应力轴循环旋转条件下重塑黏土变形特性试验研究

Undrained response of reconstituted clay subjected to cyclic rotation of principal stress

通过一组重塑黏土的循环扭剪试验对主应力轴单纯循环旋转条件下重塑黏土的不排水变形特性进行研究,试验中考虑中主应力系数、剪应力水平以及固结方式等的影响。试验结果表明即使在剪应力水平很低(q/p=0.033)的条件下,主应力轴单纯旋转也会引起重塑黏土显著的孔压累积。随着循环次数的增加不排水条件下重塑黏土会因为变形的迅速发展而破坏。中主应力系数对变形发展规律有较大影响,对孔压累积的影响相对不显著,相同剪应力水平下b=1时重塑黏土破坏时所需的循环次数最少,但孔压累计最慢。通过试验结果的分析认为旋转剪应力会对土体微观结构产生扰动而使土体颗粒重新排列,主应力轴旋转引起的变形特性主要还是归因于土体的塑性各向异性特性。

A series of undrained triaxial-torsional shear tests were carried out on reconstituted clay,and the response of reconstituted clay to cyclic rotation of principal stress was studied with different coefficients of intermediate principal stress,shear stresses and consolidation conditions. The experimental results show that even at the low shear stress level of q /p = 0. 033,the pore water pressure may accumulate due to the pure principal stress rotation. With the increase of cycles,reconstituted clay may fail due to the significant increase of deformation. The effect of magnitude of intermediate principal stress was more significant on the strain than on the pore water pressure and at the same shear stress level b =1 may lead to the least number of cycles at failure,while the pore pressure may accumulate at the slowest speed for b =1. From the test results,it may be concluded that the deformation behavior of reconstituted clay under cyclic rotation of principal stress may be attributed to the anisotropy of soil plasticity.