分级加卸载下深部粉砂岩三轴蠕变特性试验研究  

Experimental study on triaxial creep behavior of deep siltstone under stepwise loading and unloading

作　　者：高文华[1] 刘正[1] 刘栋[1] 赵延林[1] 

机构地区：[1]湖南科技大学岩土工程研究所,湖南湘潭411201

出　　处：《自然灾害学报》2012年第5期127-134,共8页Journal of Natural Disasters

基　　金：国家自然科学基金资助项目(41272324);湖南省教育厅重点资助项目(09A028);湖南省科技计划项目(2010FJ3046)

摘　　要：采用分级增量循环加卸载方式,对湖南湘煤集团牛马司矿业公司水井头煤矿-300米东大巷二煤层底板粉砂岩进行了三轴蠕变特性试验,详细探讨了其轴向蠕变和变形模量的变化特征,分析了围压对蠕变和破坏的影响;研究了该类岩石各蠕变阶段非线性黏弹塑性变形特征。试验结果表明,在围压条件下,加速蠕变阶段较明显,岩样经过典型的蠕变三阶段后产生明显的黏塑性破坏;变形模量随应力水平的增大和时间的增长逐渐减小,直至趋于某一稳定值;瞬弹应变、瞬时总应变、粘弹性应变和总蠕变均随应力水平增大而增大;围压越大,岩石蠕变值越小,变形模量越小,塑性变形所占比重越大,非线性流变越明显。加大围压可以减缓岩石的蠕变破坏时间,围压越大破坏时的应变值也越高。表明围压对岩石蠕变有明显的约束作用。By means of stepwise incremental cycling loading and unloading,the experiment was done on triaxial creep properties of siltstone at the floor of coal seam II in east roadway beneath 300 m of Shuijingtou coalmine of Niumasi Mining Company of Hunan Xiangmei Group.The characteristics of axial creep and deformation modulus were discussed here in detail.The influence of confining pressures on creep and destruction was analyzed.The nonlinear viscoelasto-plastic characteristics of the siltstone in each creep stage were studied.The test results show that the stage of accelerating creep is obvious under the conditions of confining pressure and the viscoplastic strain damage occurs after typical three phases of creep.With the growth of stress level and time,deformation modulus decreases gradually until it tends to be a constant value.The instantaneous elastic strain,instantaneous total strain,viscoelastic strain and total creep all increase with the growth of stress level.The higher the confining pressure is,the smaller the value of creep and the deformation modulus is,the greater the proportion of plastic deformation is,and the more obvious the nonlinear rheological property is.The time of creep damage can be slowed down by increasing confining pressure.The larger the confining pressure is,the higher the damaged strain is.All these experiments show that the confining pressure has obvious constraint effect on rock creep.

关 键 词：分级加卸载 三轴蠕变 黏弹塑性 粉砂岩 

分 类 号：TU413[建筑科学—岩土工程]