压缩荷载作用下岩石类材料裂缝扩展预测理论的改进及验证  

Improvement and verification of crack propagation prediction theory for rock mate⁃rials under compressive load

作　　者：李修磊 刁航 陈臣 黄锋[2] 凌天清[2] 曾彬 LI Xiulei;DIAO Hang;CHEN Chen;HUANG Feng;LING Tianqing;ZENG Bin(School of River and Ocean Engineering,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学河海学院,重庆400074 [2]重庆交通大学土木工程学院,重庆400074

出　　处：《河南理工大学学报（自然科学版）》2024年第5期163-172,共10页Journal of Henan Polytechnic University（Natural Science）

基　　金：国家自然科学基金资助项目(52078090,42202322);全职博士后留渝资助项目(Z32200078);中国博士后科学基金资助项目(2018M633627XB)。

摘　　要：目的为提高岩石类材料裂缝扩展预测的准确性,弥补传统最大周向应力准则(MTS准则)未考虑裂缝尖端应力场非奇异应力项(T应力)和裂缝几何特性的缺陷,方法基于传统MTS准则,考虑T应力和裂缝几何特性对裂缝尖端应力场的影响,建立一种新的岩石非闭合裂缝断裂准则。采用中心含有非闭合裂缝的岩石试件进行单轴压缩试验,将准则预测值同试验测得起裂角θ比较,分析引入裂缝几何特性和T应力后对裂缝起裂情况以及裂缝尖端应力场的影响,检验本文准则的合理性。结果研究表明:仅引入裂缝几何特性,裂缝宽长比(b/a)增加,会促使应力强度因子KI增加,导致裂缝尖端受拉伸作用形成张拉裂缝,使得复合型断裂中的I型开裂增多;同时引入裂缝几何特性和T应力时,裂缝宽长比(b/a)增加会引起裂角θ减小和最大周向应力(σθ)_(max)增加;且引入T应力后,起裂角θ和起裂荷载更加接近实际值,此时T应力起抑制裂缝起裂作用,且起裂角θ伴随裂缝倾角β增大逐渐由正倾开裂过渡为反倾开裂。结论采用引入T应力和裂缝几何特性的裂缝断裂准则能更精确预测裂缝倾角β为0°~60°时的起裂角θ。Objectives The objective was to improve the accuracy of crack propagation prediction for rock materials by addressing deficiencies in the traditional maximum circumferential stress criterion(MTS crite⁃rion),which disregarded the non-singular stress term(T-stress)in the crack tip’s stress field and the crack geometrical properties.Methods Based on the conventional MTS criterion,a new fracture criterion for non-closed fractures in rocks was established by considering the effects of T-stress and fracture geometry properties on the fracture tip stress field.Uniaxial compression tests were conducted on rock specimens with non-closed cracks in the center.The predicted criterion values were compared with the measured crack angle(θ),and the influence of fracture geometry and T-stress on crack initiation and the crack tip stress field was analyzed to assess the validity of the proposed criterion.Results The results of the research indi⁃cated that only considering fracture geometry features led to an increase in the crack width-length ratio(b/a),causing a rise in the stress intensity factor(K_(I)).This increase resulted in tension fractures forming due to tensile action at the fracture tip,thereby increasing the type I cracks in the composite fracture.When the geometric characteristics of the crack and T-stress were introduced simultaneously,an increase in the crack width ratio(b/a)reduced the crack angleθand increased the maximum peripheral stress(σθ)_(max).With the introduction of T-stress,the crack starting angle(θ)and the crack starting load are closer to the actual value,then the T-stress plays a crucial role in suppressing crack initiation.Additionally,the crack starting angle(θ)gradually transitioned from positive to negative cracking with the increase of the crack dip angle(β).Conclusions The crack initiation criterion,considering T-stress and crack geometry,can more accurately predict the crack initiation angle(θ)within the range of 0°to 60°of the crack dip angle(β).

关 键 词：断裂准则 非闭合裂缝 T应力 裂缝几何特性 起裂角 

分 类 号：TU452[建筑科学—岩土工程]