考虑中间主应力的粉砂岩侧向卸荷力学特性试验研究  

Experimental study on lateral unloading mechanical properties of siltstone considering intermediate principal stress

作　　者：马钰沛 李江腾[1] 刘双飞 MA Yupei;LI Jiangteng;LIU Shuangfei(School of Resources and Safety Engineering,Central South University,Changsha 410083,China)

机构地区：[1]中南大学资源与安全工程学院

出　　处：《中南大学学报（自然科学版）》2019年第11期2792-2800,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51979293,51774322);湖南省水利厅科技项目(2015131-5)~~

摘　　要：利用TRW-3000型岩石真三轴试验系统开展粉砂岩真三轴侧向卸荷试验,研究不同中间主应力系数b条件下粉砂岩卸荷破坏、变形特征,并基于Mogi-Coulomb强度准则,探讨岩体强度特征。研究结果表明:在真三轴侧向卸荷应力条件下,随着中间主应力增大,粉砂岩试样卸荷破坏模式由剪切-张拉复合破坏转变为板裂破坏,剪切破断角随b增大呈线性增大;应力-应变曲线有较明显的阶段性,随着中间主应力增大,破坏时最大主应变ε1、最小主应变ε3增大,体积应变εV减小,扩容趋势更加明显;在卸荷过程中,变形模量随卸荷量增加呈负指数关系降低;采用Mogi-Coulomb准则对真三轴侧向卸荷试验强度进行拟合分析,回归方程满足显著性水平α=0.01的F检验要求,Mogi-Coulomb强度准则能够较好地用于描述不同中间主应力条件下的粉砂岩侧向卸荷强度关系。By using the rock true triaxial test system to carry out the lateral unloading test of siltstone true triaxial,unloading failure and deformation feature of siltstone were studied under different intermediate principal stress coefficients b, and the strength feature of rock mass was discussed based on the strength criteria of Mogi-Coulomb. The results show that under the condition of true triaxial lateral unloading stress, with the increase of the intermediate principal stress, the unloading failure mode of the siltstone sample changes from shear-tension composite failure to fracture failure, and the shear fracture angle increases linearly with the increase of b. The stress-strain curve exists an obvious stage. As the intermediate principal stress increases, the maximum principal strain ε1 and the minimum principal strain ε3 increase, and the volume strain εVdecreases during failure. The trend of expansion is obvious. During the unloading process, the deformation modulus decreases with the increase of unloading amount in a negative exponential relationship. The Mogi-Coulomb criterion is used to analyze the true triaxial lateral unloading test intensity, and the regression equations passes the F-test at a higher significance level of 0.01. The Mogi-Coulomb strength criterion can be applied to describe the lateral unloading strength relationship of siltstone under different middle main stress conditions.

关 键 词：真三轴 卸荷 中间主应力 破坏 变形 Mogi-Coulomb强度准则 

分 类 号：TU45[建筑科学—岩土工程]