侧限压缩条件下土体的侧应力松弛试验研究

侧向应力松弛是侧限压缩土体的重要流变性质之一。通过在改装的固结仪上进行的土体侧限流变试验表明，在恒载侧限压缩条件下，土体的侧应力松弛曲线与竖向蠕变曲线同步出现不稳定、稳定、急剧变化3个阶段。将试验结果结合土的结构颗粒定向排列理论和强度理论探索了土体侧应力松弛的机制并得出结论：侧应力松弛曲线的3阶段特征是由于土体结构连接的压密恢复与剪切破坏相互作用所致；而侧应力松弛稳定的极限状态是由土的抗剪强度控制。此外，较高的应力水平将会使土体侧应力松弛程度相比低应力水平时更为显著。该分析结论为进一步研究地基长期承载力和地基沉降的关系奠定了基础。

Lateral stress relaxation of soil under confined compression condition

Lateral stress relaxation is one of the important rheological characteristics of soil under confined compression condition.Confined rheological tests are carried out on the revamped consolidation apparatus.The results show that the lateral stress relaxation curves and the vertical creep curves of soil appear synchronous process which consists of unsteady,steady and sudden change stages under confined compression with constant load.Then the mechanism of lateral stress relaxation is analyzed based on the test curves by using the theory of structural grain directional array and the strength theory of soil.Some conclusions can be achieved through mechanism analysis that the three stages relaxation characteristics of lateral stress are induced by the interaction between compaction recovery and shear fracture of soil structure;and the limit state of lateral stress in stable relaxation stage is controlled by the shear strength of soil.In addition,the relaxation extent of lateral stress in higher stress level is more remarkable than in lower stress level.These conclusions will be favorable for further study of the relation between long-term bearing capacity and settlement of ground.