循环加载保载卸载下泥质砂岩滞后破坏特性  

Hysteresis failure behavior of argillaceous sandstone under cyclic loading, load-holding and unloading

作　　者：张后全[1] 茅献彪[1] 石浩[1] 吴宇[1] 陈彦龙[1] 

机构地区：[1]中国矿业大学深部岩土力学与工程国家重点实验室,力学与土木工程学院,江苏徐州221116

出　　处：《采矿与安全工程学报》2018年第1期163-169,187,共8页Journal of Mining & Safety Engineering

基　　金：国家重点基础研究发展计划(973)项目(2013cB227900);国家自然科学基金项目(51227003,51404262,51323004)

摘　　要：采用TATW-2000电液伺服试验机对泥质砂岩试件进行单轴循环加载保载卸载破坏试验:首先对试件施加轴压至预定值,然后保持该压力值约115 s左右,以使泥质砂岩试件变形有足够时间达到一个相对稳定状态,以至于轴向变形速率小于0.005 mm/h;当试件在该压力作用下变形相对稳定后,再进行轴压卸载和下一个循环加载、保载、卸载过程;如此循环,直到试件在保载过程中发生破坏。本次试验研究结果表明,在循环加卸载试验中,无论是加载还是卸载过程,岩石变形都滞后于外部应力变化;在轴压加载至设定值并进入保载过程中的较短时间范围内,岩石变形并不立即停止而是随时间有一定程度的缓慢增长,即具有变形滞后特性;在循环加载、保载以及卸载条件下,岩石试件最终破坏前会产生大量的竖向裂纹;与常规单轴压缩试验相比,在单轴循环加载、保载、卸载条件下的泥质砂岩试件滞后破坏时的平均单轴抗压强度有所降低;在岩石恒载滞后破坏试验中,岩石滞后变形为试件达到破坏所需弹性能补充提供了供给途径。Cyclic loading, load-holding and unloading tests of argillaceous sandstone samples were conducted by adopting the TATW-2000 electro hydraulic servo testing machine. In the tests, firstly the axial load on the samples was applied to a predetermined value which was then kept for about 115 se- conds. Therefore, the argillaceous sandstone samples＇ deformation has enough time to reach a relatively stable state that the velocity of axial deformation being less than 0.005 mm/h. When the samples＇ de- formation under such an axial pressure became relatively stable, the axial load was unloaded. Then the circle of loading, load-holding and unloading was repeated several times until the samples are damaged in the process of load-holding. Experimental results show that in a cyclic loading and unloading process, rock deformation always lags to the outer loading variation. When the load reaches a designed value and is kept for a certain short time, the samples＇ deformation does not immediately stop, instead, it shows a certain slow growth with the time. This phenomenon is called the deformation hysteresis. In the cyclicloading, load-holding and unloading process, large amount of vertical cracks generate in rock samples before the ultimate unstable failure. Compared with the conventional uniaxial compression tests, the av- erage peak strengths of hysteresis failure under cyclic loading, load-keeping and unloading tests de- creases significantly. In rock hysteresis failure experiments, hysteresis deformation provides an ap- proach to supply the elastic energy that is required by the rock failure.

关 键 词：循环荷载 滞后破坏 强度特征 能量分析 

分 类 号：O319.56[理学—一般力学与力学基础]