循环荷载作用下冻结灰砂岩强度特征与弹性模量演化规律

针对典型中生代富水弱胶结地层中的灰砂岩,利用TDW-200冻土三轴试验机对冻结饱水灰砂岩进行常规三轴压缩试验和循环加卸载试验,分析不同围压条件下的强度特征,重点研究了循环加卸载作用下冻结灰砂岩弹性模量的演化规律。试验结果表明:循环加卸载时,在低围压下峰值强度有所增加,而在高围压下峰值强度有"弱化"的现象;冻结灰砂岩试样加卸载全过程中弹性模量的变化规律与加卸载路径变化趋势具有一致性;单个滞回环内,切线弹性模量随着偏应力水平的增加呈现出先增加后减小的趋势,同一偏应力水平下,切线模量随循环次数的增加也表现为先增加后减小趋势。

Strength characteristics and elastic modulus evolution of frozen gray sandstone under cyclic loading

The triaxial compression test and cyclic loading test were carried out on frozen sandstone samples cut from weakly cemented water rich Mesozoic gray sandstones using TDW 200 frozen soil triaxial test apparatus.The strength characteristics and the evolution rules of elastic modulus were studied based on the experimental results.The test results show that while the peak strength increases under low confining pressure,it decreases under high confining pressure in cyclic loading test;during the whole process of cyclic loading,the tendency of elastic modulus is consistent with the path of cyclic loading;for each hysteretic loop,the tangent modulus increases first then decreases with the increase of deviatoric stress,it has the same tendency with the increase of cycle number when the deviatoric stress is the same.