北山花岗岩短长期常规三轴力学特性试验研究

为研究北山花岗岩的物理力学特性，开展了常规三轴、蠕变和松弛试验，研究过程与结论如下：（1）开展北山花岗岩在不同围压条件下的常规三轴压缩试验，对比分析试样的变形和破坏形式等力学特征，得出北山花岗岩岩石破坏时的不可恢复变形较小，且随着围压增大未出现脆-延性转变现象的结论；（2）开展北山花岗岩单级蠕变试验及不同围压条件下的多级蠕变试验，分析不同偏应力的形变和单级蠕变的蠕变速率，得出北山花岗岩的蠕变形式为非稳定蠕变，其应变曲线出现了典型的蠕变三阶段特征的结论；（3）开展北山花岗岩单级应力松弛试验及循环松弛试验，分析偏应力的变化规律，得出北山花岗岩在应力松弛过程的初始松弛阶段，其偏应力下降速率很快，在较短时间内即能够达到稳定状态的结论。

Experimental Study on Short-and Long-Term Mechanical Properties of Beishan Granite Under Conventional Triaxial Compression

In order to study the physical and mechanical properties of Beishan granite, conventional triaxial, creep, and relaxation tests were conducted. The main research process and conclusions are as follows:(1) Conventional triaxial compression tests were conducted on Beishan granite under different confining pressure conditions and mechanical characteristics, such as the deformation and failure modes of the samples, were compared and analyzed. It was found that the irreversible deformation of Beishan granite rock during failure was relatively small and there is no brittle ductile transition phenomenon with the increase of confining pressure; (2) Single stage creep tests on Beishan granite and multi-level creep tests were conducted under different confining pressure conditions and the deformation of different deviatoric stress pairs and the creep rate of single stage creep were analyzed, which showed that the creep form of Beishan granite was unstable creep, and its strain curve showed typical third-order creep characteristics; and (3) Single stage stress relaxation and cyclic relaxation tests were conducted on Beishan granite and the variation law of deviatoric stress was analyzed, which found that the deviatoric stress of Beishan granite decreased rapidly during the initial relaxation stage of stress relaxation process and reached a stable state in a relatively short period of time.