芒硝力学特性及其本构模型

为了解芒硝的力学特性，在MTS815岩石伺服试验机上对其进行了力学试验，包括单轴压缩试验和等围压三轴压缩试验，并对其强度和变形特征进行了分析。分析表明，芒硝在单轴压缩下表现应变软化特性，且强度很低，属于软岩的范畴；当围压在5 MPa以上时，芒硝表现明显的应变硬化特征。根据芒硝变形特性，提出了以岩石塑性应变作为微元统计分布变量，同时引入一个能够反映岩石破坏部分承载力的比例系数，建立了能够反映岩石应变硬化特征的损伤统计本构模型，并用试验资料对其进行了验证。结果表明，该模型能够较好地反映芒硝岩样的破坏全过程，且在单轴压缩下，芒硝微元破坏部分承受的力很小，可以忽略；而在高围压作用下，微元破坏部分承受的力比较大，不能忽略。

Mechanical properties and constitutive model of thenardite

To study the mechanical properties of thenardite, both uniaxial and triaxial compression tests were carried out with MTS815 servo controlled rock mechanical test system. The experimental results indicate that the strength of thenardite under uniaxial compression is very low, and so, it is a kind of soft rock. And it has strain softening characteristics under uniaxial compression but strain hardening characteristics when the confining pressure is more than 5MPa. Then, according to this distortion character of thenardite, a rock statistical damage constitutive model was established by taking the plastic strain as the distribution variable and a coefficient which can reflect the load capacity of damaged part of rock was introduced. Finally, the constitutive model was confirmed by the test data of thenardite.The results show that the proposed model can well reflect the failure process of thenardite. It is reasonable to ignore the load capacity of the damaged part of thenardite under uniaxial compression, but unreasonable to ignore the load capacity of the damaged part of thenardite under triaxial compression.