摘要
为探究深部地下工程中加锚节理岩体的剪切特性,本文开展了恒刚度边界条件下加锚节理岩体的直剪试验,探究了不同节理面粗糙度、法向刚度和初始法向应力对加锚节理岩体剪切力学特性的影响,并结合PFC数值模拟,分析了不同锚杆弹性模量影响下锚固体系的宏观力学特性和细观裂纹变化特征.结果表明:节理面粗糙度对剪切强度影响显著,粗糙度越大,剪切强度越高;锚杆可提高试样的整体抗剪强度,但法向刚度和初始法向应力对锚杆的锚固效果有不同的影响,存在最优范围;试件内部裂纹以张拉裂纹为主,随着锚杆弹性模量的增加,锚固体的峰值剪切强度和内部裂纹数量都呈现增加趋势,但增加速率在变小;锚杆内部剪切应力曲线和轴向应力曲线变化相似,与锚杆弹性模量有明显关系,弹性模量越大,应力增长越剧烈,达到屈服强度后增加变得十分缓慢.
Abstract
To investigate the shear characteristics of anchored jointed rock masses in deep underground engineering,this paper conducted direct shear tests on anchored jointed rock masses under constant normal stiffness boundary conditions.The study explored the effects of different joint surface roughness,normal stiffness,and initial normal stress on the shear mechanical properties of anchored joints.The numerical simulation using Particle Flow Code(PFC)was conducted to analyze the macroscopic mechanical characteristics and mesoscopic crack variation characteristics of the anchorage system under the influence of different elastic moduli of bolts.The results indicate that the joint surface roughness significantly affects shear strength,with greater roughness leading to higher shear strength.Anchors can enhance the overall shear strength of the specimens,but normal stiffness and initial normal stress have varying impacts on the anchoring effect and exists an optimal range.The internal cracks of the specimens are mainly tensile cracks.As the elastic modulus of the anchor increases,both the peak shear strength of the anchored system and the number of internal cracks increase at first,then trend to flatten.The shear stress and axial stress curves within the anchor exhibit similar changes and are significantly related to the anchor's elastic modulus.A higher elastic modulus results in more pronounced stress growth,which becomes very slow after reaching the yield strength.
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