为了研究复杂应力路径下冻融循环作用对黄土强度特性的影响作用,利用真三轴试验仪对经历了不同冻融循环作用的重塑黄土,进行了等p应力路径下的固结排水剪切试验。在冻融试验中设定试样分别经历5个不同的冻融循环为0,1,3,5,10,在剪切试...为了研究复杂应力路径下冻融循环作用对黄土强度特性的影响作用,利用真三轴试验仪对经历了不同冻融循环作用的重塑黄土,进行了等p应力路径下的固结排水剪切试验。在冻融试验中设定试样分别经历5个不同的冻融循环为0,1,3,5,10,在剪切试验中控制球应力p恒定分别为200,300,400 k Pa,并分别设定五个中主应力参数b值为0,0.25,0.5,0.75,1。试验结果给出重塑黄土的应力应变曲线,重塑黄土p-q面上的强度破坏线,研究了冻融循环作用在不同b时对土体应力应变的曲线的影响及冻融作用和b值对重塑黄土强度参数的影响。研究结果表明:冻融作用对土体的应力应变曲线形态基本没有影响,而b的改变对对其形态影响显著。抗剪强度随冻融次数先降低而后略有升高最后趋于稳定,而随着b值一直在减小。黏聚力随冻融次数先减小而后趋于稳定,随b值先增大而后减小;内摩擦角随冻融次数无规律的小范围波动,随b值小范围的先增大后减小。展开更多
Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this devic...Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this device,the complete shearedeformation process and long-term shear creep tests could be performed on rocks under constant normal stiffness(CNS)or constant normal loading(CNL)conditions in real-time at high temperature and true-triaxial stress.During the research and development process,five key technologies were successfully broken through:(1)the ability to perform true-triaxial compressioneshear loading tests on rock samples with high stiffness;(2)a shear box with ultra-low friction throughout the entire stress space of the rock sample during loading;(3)a control system capable of maintaining high stress for a long time and responding rapidly to the brittle fracture of a rock sample as well;(4)a refined ability to measure the volumetric deformation of rock samples subjected to true triaxial shearing;and(5)a heating system capable of maintaining uniform heating of the rock sample over a long time.By developing these technologies,loading under high true triaxial stress conditions was realized.The apparatus has a maximum normal stiffness of 1000 GPa/m and a maximum operating temperature of 300C.The differences in the surface temperature of the sample are constant to within5C.Five types of true triaxial shear tests were conducted on homogeneous sandstone to verify that the apparatus has good performance and reliability.The results show that temperature,lateral stress,normal stress and time influence the shear deformation,failure mode and strength of the sandstone.The novel apparatus can be reliably used to conduct true-triaxial shear tests on rocks subjected to high temperatures and stress.展开更多
文摘为了研究复杂应力路径下冻融循环作用对黄土强度特性的影响作用,利用真三轴试验仪对经历了不同冻融循环作用的重塑黄土,进行了等p应力路径下的固结排水剪切试验。在冻融试验中设定试样分别经历5个不同的冻融循环为0,1,3,5,10,在剪切试验中控制球应力p恒定分别为200,300,400 k Pa,并分别设定五个中主应力参数b值为0,0.25,0.5,0.75,1。试验结果给出重塑黄土的应力应变曲线,重塑黄土p-q面上的强度破坏线,研究了冻融循环作用在不同b时对土体应力应变的曲线的影响及冻融作用和b值对重塑黄土强度参数的影响。研究结果表明:冻融作用对土体的应力应变曲线形态基本没有影响,而b的改变对对其形态影响显著。抗剪强度随冻融次数先降低而后略有升高最后趋于稳定,而随着b值一直在减小。黏聚力随冻融次数先减小而后趋于稳定,随b值先增大而后减小;内摩擦角随冻融次数无规律的小范围波动,随b值小范围的先增大后减小。
基金financial support from the National Natural Science Foundation of China(Grant Nos.52209125 and 51839003).
文摘Deep engineering disasters,such as rockbursts and collapses,are more related to the shear slip of rock joints.A novel multifunctional device was developed to study the shear failure mechanism in rocks.Using this device,the complete shearedeformation process and long-term shear creep tests could be performed on rocks under constant normal stiffness(CNS)or constant normal loading(CNL)conditions in real-time at high temperature and true-triaxial stress.During the research and development process,five key technologies were successfully broken through:(1)the ability to perform true-triaxial compressioneshear loading tests on rock samples with high stiffness;(2)a shear box with ultra-low friction throughout the entire stress space of the rock sample during loading;(3)a control system capable of maintaining high stress for a long time and responding rapidly to the brittle fracture of a rock sample as well;(4)a refined ability to measure the volumetric deformation of rock samples subjected to true triaxial shearing;and(5)a heating system capable of maintaining uniform heating of the rock sample over a long time.By developing these technologies,loading under high true triaxial stress conditions was realized.The apparatus has a maximum normal stiffness of 1000 GPa/m and a maximum operating temperature of 300C.The differences in the surface temperature of the sample are constant to within5C.Five types of true triaxial shear tests were conducted on homogeneous sandstone to verify that the apparatus has good performance and reliability.The results show that temperature,lateral stress,normal stress and time influence the shear deformation,failure mode and strength of the sandstone.The novel apparatus can be reliably used to conduct true-triaxial shear tests on rocks subjected to high temperatures and stress.
