摘要
扩容效应是岩石三轴压缩条件下体积变化的显著特性,是岩石体积非线性膨胀的重要表现。为考察岩石的扩容特性,分析塑性特性与应力水平对扩容的影响机制,阐释岩石全过程偏应力-应变曲线特征,以西南地区某引调水工程粉砂质泥岩为研究对象,开展了1~25 MPa围压水平下的三轴压缩试验,引入Mohr-Coulomb强度准则与塑性参数,对岩石的扩容特性进行研究。结果显示:(1)岩石的扩容应力与残余应力分别为峰值应力的0.65与0.58,各项强度指标与围压水平均有着明显的线性关系,符合Mohr-Coulomb强度准则;(2)发生扩容后,岩石内摩擦角与黏聚力随塑性参数的增大经历了先增大后减小的变化,且变化特征有一定的不同步性,基于Mohr-Coulomb强度准则和塑性参数的拟合模型能够描述岩石扩容发生后的全过程偏应力-应变曲线;(3)扩容角及扩容指数随围压的增大而呈负指数型减小,破裂面倾角随围压的增大而逐渐增大,并逐渐趋于稳定。结果表明:岩石扩容后的变形过程与应力水平及塑性特性密切相关,且围压对岩石扩容具有抑制作用。
The volume dialation effect is a significant characteristic of rock volume change under triaxial compression conditions,and is an important manifestation of the nonlinear expansion of rock volume.In order to examine the dialation characteristics of rock,analyze the influence mechanism of plastic characteristics and stress level on the dialation characteristics,and explain the deviatoric stress-strain curve characteristics of the rock in the whole process,taking the silty mudstone of a water diversion project in southwest China as the research object,a study was carried out.In the triaxial compression test under the confining pressure level of 1~25 MPa,the Mohr-Coulomb strength criterion and plastic parameters were introduced to study the dialation characteristics of the rock.The results show:(1)The dialation stress and residual stress of the rock are 0.65 and 0.58 of the peak stress respectively,and various strength indicators have an obvious linear relationship with the confining pressure level,which is consistent with the Mohr-Coulomb strength criterion;(2)After dialation occurs,the internal friction angle and cohesion of the rock experienced changes that first increased and then decreased as the plastic parameters increased,and the change characteristics had a certain degree of asynchrony.The fitting model based on the Mohr-Coulomb strength criterion and plastic parameters can Describe the deviatoric stress-strain curve of the whole process after the rock dialation occurs;(3)The dialation angle and dialation index decrease in a negative exponential manner as the confining pressure increases,and the rupture surface inclination angle gradually increases with the increase of the confining pressure.and gradually stabilized.The deformation process of rock after dialation is closely related to the stress level and plastic properties,and the confining pressure has an inhibitory effect on rock dialation.
作者
张昊
周黎明
罗荣
张利洁
ZHANG Hao;ZHOU Liming;LUO Rong;ZHANG Lijie(Key Laboratory of Geotechniacal Mechanics and Engineering of Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan 430010,Hubei,China)
出处
《水利水电技术(中英文)》
北大核心
2025年第S1期594-602,共9页
Water Resources and Hydropower Engineering
基金
中央级公益性科研院所基本科研业务费(CKSF2023316/YT)
