循环加卸载下高脆性黑砂岩强度及损伤试验研究  

Experimental study on strength and damage characteristics of high brittle black sandstone under cyclic loading and unloading test

作　　者：陈珺 陈念辉 侯靖 CHEN Jun;CHEN Nianhui;HOU Jin(PowerChina Huadong Engineering Corporation Limited,Hangzhou 311122,China)

机构地区：[1]中国电建集团华东勘测设计研究院有限公司,浙江杭州311122

出　　处：《人民长江》2022年第6期180-185,206,共7页Yangtze River

摘　　要：为研究高应力循环加卸载条件下脆性硬岩强度特性和参数演化规律,开展了不同围压水平下的黑砂岩循环加卸载试验,获得了高脆性硬岩全过程应力应变曲线和破裂特征,并借助塑性内变量来表征岩石损伤程度,研究了变形与强度参数随损伤的演化规律。研究结果表明:①循环加卸载试验中黑砂岩应力应变曲线存在屈服平台,峰后应力快速跌落,试样以剪切破坏为主;②从初始屈服到残余变形过程中,黑砂岩弹性模量呈先减小后增大的变化特征,在塑性内变量为0.80~0.85左右达到最小值,泊松比则呈先增大后减小的趋势;③黏聚力先随塑性内变量不断减小,在接近残余强度时保持稳定,而内摩擦角则呈先增大后减小的特征,强度参数与塑性内变量之间的关系可采用线性分段函数表示。To study the strength characteristics and mechanical parameter evolution of brittle hard rock under high stress loading and unloading cycles,a series of cyclic loading and unloading tests on black sandstone with different confining pressure levels were carried out.The stress-strain curves and fracture characteristics of the high brittle hard rock during the whole process were obtained.By adopting plastic internal variable to represent the degree of rock damage,the evolution of deformation and strength parameters with damage was studied.The research results were as follows:①In the cyclic loading and unloading test,the stress-strain curve of black sandstone had a yield platform;the post-peak stress dropped rapidly,and the specimen failure mechanism was mainly sheared.②From the initial yield to the residual deformation,the elastic modulus of black sandstone first decreased and then increased,and it reached the minimum value when the plastic internal variable was about 0.80~0.85;the Poisson s ratio first increased and then decreased.③The cohesion decreased with increasing plastic internal variable at first,and remained stable when approaching the residual strength;the internal friction angle first increased and then decreased.The relationship between the strength parameters and the plastic internal variable can be expressed by linear piecewise function.

关 键 词：循环加卸载试验 脆性硬岩 峰值强度 力学参数 塑性内变量 

分 类 号：TU45[建筑科学—岩土工程]