破裂砂岩蠕变试验研究

EXPERIMENTAL RESEARCH ON CREEP OF FRACTURED SANDSTONE

为了认识破裂砂岩蠕变特征,利用MTS815岩石力学试验系统,对永川煤矿T3xj6砂岩进行一系列加载水平的峰后蠕变试验,并用改进的西原模型描述破裂(峰后)砂岩蠕变全过程。试验结果表明,破裂砂岩失稳蠕变过程与煤岩一般的蠕变规律相似;破裂砂岩也存在长期强度,其值可根据岩石加载过程中的应力–应变关系通过理论分析的方法得出;破裂砂岩蠕变全过程可用改进的西原模型描述,对加载应力大于Sh(破裂砂岩的长期强度)的情况,模型的参数可用最小二乘法求得;影响破裂砂岩蠕变成功进行的因素是岩样的均质性、加载控制和岩样移送三轴压力室前密封的可靠性。研究结论对揭示地下工程灾害发生的时滞性、确定掘进巷道围岩支护参数等有重要的参考意义。

In order to understand the creep characteristics of fractured sandstone,a series of creep tests of fractured sandstone from T3xj6 sandstone in Yongchuan mine are carried out by a MTS815 rock testing system;and the whole process of fractured sandstone is described with modified Nishihara model. The results show that creep law of fractured sandstone is similar to those of the general creep characteristics of coal and rock. Fractured sandstone also has long-term strength,which is determined according to the stress-strain relationship obtained by theoretical analysis. The whole process of fractured sandstone can be described with modified Nishihara model. When load stress is greater than long-term strength of fractured sandstone,unknown parameters of modified Nishihara model could be achieved with least squares method. The homogeneity,load control and leak tightness of rock samples can influence the successful creep of fractured sandstone. These results have great significance to revealing time lag of underground engineering disasters;and supporting parameters of surrounding rock mass in excavation roadway can also be determined.