风化作用下层状板岩Ⅰ型断裂特性试验研究  

Experimental investigation on mode I fracture behaviors of layered slate under condition of air-weathering

作　　者：李二强 张龙飞 赵宁宁 朱天宇 张洪昌 冯吉利 LI Erqiang;ZHANG Longfei;ZHAO Ningning;ZHU Tianyu;ZHANG Hongchang;FENG Jili(School of Civil Engineering,Luoyang Institute of Science and Technology,Luoyang 471000,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,Beijing 100083,China;School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]洛阳理工学院土木工程学院,河南洛阳471000 [2]深部岩土力学与地下工程国家重点实验室,北京100083 [3]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《中南大学学报（自然科学版）》2022年第4期1406-1415,共10页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2016YFC0600901);国家自然科学基金资助项目(41172116,U1261212)。

摘　　要：以甘肃岷县在建木寨岭隧道层状炭质板岩为研究对象,首先对即时烘干试样(试样加工完成后立即用烘箱烘干)和静置风化(加工后室内常温通风放置60 d)试样开展巴西劈裂试验,然后,对静置风化试样开展直缝半圆盘(SCB)试样三点弯试验,系统研究层状炭质板岩抗拉强度及其I型断裂特性。研究结果表明:即时烘干和静置风化炭质板岩试样抗拉强度均与层理关系密切,且受水−岩及风化综合作用,其抗拉力学性质显著劣化;不同层理倾角下静置风化炭质板岩SCB试验荷载−位移曲线形式具有一定相似性,均呈现出压密→近线弹性→塑性弱屈服→瞬时破坏跌落的发展过程;当层理倾角为0°,30°,45°,60°和90°时,试样断裂韧度随倾角增大而逐渐减小,依次为0.168,0.137,0.121,0.116和0.097 MPa·m^(1/2),而在divider状态下试样断裂韧度陡增至最大即0.195 MPa·m^(1/2),体现了层理、水−岩及风化作用对炭质板岩张拉断裂特性的显著影响;各组SCB试样均从直缝尖端起裂但其扩展路径因受层理影响而存在显著差异;根据试验数据拟合所得断裂韧度经验公式的可决系数R2为0.97,说明该公式可用于预测板岩等层状岩相关断裂参数及指导工程实践。The layered carbonaceous slate sampled from Muzhailing tunnel in Min county was taken as the research object,Brazilian splitting experiments were conducted on drying(instant drying in oven after fabrication)and static air-weathering(room temperature ventilation for 60 d after fabrication)specimens,and semi-circular bend(SCB)tests were conducted on static air-weathering specimen.Then the tensile strength and mode I fracture behaviors of the layered carbonaceous slate were explored systematically.The results show that the tensile strength of the two kinds of layered slates are all affected by the bedding,while water-rock interaction(WRI)and natural weathering have great influence on its deteriorated tensile property.The SCB load-displacement curves of airweathering carbonaceous slates with different bedding angles are similar,and have the development process of compaction−near linear elasticity−plastic weak yield−instantaneous failure drop.As the bedding angle increases from 0°to 30°,45°,60°and 90°,mode I fracture toughness decreases from 0.168 to 0.137,0.121,0.116 and 0.097 MPa·m^(1/2),respectively,while the fracture toughness increases sharply to the maximum value of 0.195 MPa·m^(1/2) for the divider type,which shows the significant influence of bedding,WRI and air-weathering on the tensile fracture behavior.All SCB specimens crack from the notch tip,but the propagation path is different because of the influence of bedding.The R2 of the fitted empirical formula of fracture toughness based on the test data is 0.97,which indicates that the formula can be applied to predict the fracture parameters of the layered rock mass and guide the engineering practice.

关 键 词：层状板岩 水−岩作用 风化 抗拉强度 断裂韧度 断裂形态 

分 类 号：TU45[建筑科学—岩土工程]