应变空间的软岩统一弹塑性软化本构模型

为使以拉为正的统一强度理论表达式适用于岩土工程界以压为正的习惯表达，首先将以压为正的单向压缩和单向拉伸试验条件代入统一强度理论表达式，确定了相关参数，建立了以压为正的统一强度理论表达式，该表达式考虑了材料拉压不等及中间主应力的影响．将所建立的统一强度理论表达式引入应变空间，针对一种硅藻质软岩材料，利用基于应变空间的弹塑性本构方程对软岩的软化模型进行了分析和探讨，建立了应变空间表述的三轴状态下的弹塑性本构关系式，并结合硅藻质软岩的三轴试验结果进行了数值模拟分析，结果表明应变空间的统一弹塑性软化本构方程的数值模拟结果非常接近试验结果，可以很好地模拟软岩的应变软化特征．

Unified Elasto-Plastic Softening Constitutive Model of Soft Rock in Strain Space

In order to apply the unified strength theory taking tension as positive to the rock and soil engineering customarily taking compression as positive, the experimental conditions of simple compression and simple tension tests are substituted in the expression of the unified strength theory, and the relative parameters are determined, hence an expression of unified strength theory is derived for rock and soil materials, where compression is regarded as positive, and the difference of tension and compression strength of rock and soil materials and the effect of intermediate principal stress are taken into account. The presented unified strength theory is then introduced to establish an elasto-plastic softening constitutive model of triaxial state in strain space for a sort of diatom soft rock. A numerical simulation is carried out along with the test data of the diatom soft rock, and the result shows that the simulation of the unified elasto-plastic softening constitutive model coincides well with the test and describes the strain softening accurately.