泥岩三轴蠕变实验研究

采用MTS伺服刚性压力实验机对高家梁煤矿泥岩进行了三轴蠕变实验研究,获得了泥岩在不同应力条件下的蠕变变形规律。实验表明围压对泥岩微观缺陷的发展有一定的限制作用。随着围压的增加,泥岩的三轴抗压强度和弹性模量均有所增加。在围压一定时:衰减蠕变量随轴压的增大而增大;衰减蠕变率随偏应力的增加而增大;稳态蠕变率随偏应力的增大而增大。在偏应力一定时,稳态蠕变率随围压的增大而减小。当围压大于4MPa后,围压的限制作用将明显减小。随着围压继续增大,稳态蠕变率变化并不明显。根据获得的实验数据,用回归法求出了H-K模型蠕变方程的参数。结果表明H-K模型能较好地模拟实验结果。在实际工程中可通过支护增加围压以提高围岩屈服强度,也可根据实际工程中泥岩蠕变的变化趋势确定合理的二次支护时间,避免流变破坏的发生。

Study on triaxial creep test of mudstone

In order to obtain the creep deformation of mudstone in GAO Jia-liang coal under different stress conditions,a series of triaxial creep tests are carried out on the MTS servo rigidity pressure testing machine.Results show that confining pressure has certain restrictions on the development of microscopic defects of mudstone,with the increase of confining pressure,both triaxial compressive strength and elastic modulus of mudstone increase;when the confining pressure is constant,the attenuation creep amount increases with the increase of axial pressure,the decrease rate of attenuation creep rate increases with the increase of deviatoric stress,the stable creep rate increases with the increase of deviatoric stress;when the deviatoric stress is constant,the stable creep rate decreases with the increase of confining pressure,when the confining pressure is more than 4MPa,the restrictive effect of confining pressure reduces significantly,although the confining pressure continues to increase,the stable creep rate doesn’t change significantly.The parameters of creep equation of H-K model are calculated by the available test data,the result shows that H-K model can simulate the test results well.In the actual project,the confining pressure can be increased by support in order to increase the yield strength of wall rock,according to the diversification trend of mudstone creep;the second support time can be determined to avoid the occurrence of flow failure.