岩体原位点触探测试的约束刚度差异性表征及影响分析  

Characterization and influence analysis of constraint stiffness difference in in-situ cone penetration test of rock mass

作　　者：房凯[1] 王琛[1] 赵同彬[1] 张碧雯 FANG Kai;WANG Chen;ZHAO Tongbin;ZHANG Biwen(College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao 266590,China)

机构地区：[1]山东科技大学能源与矿业工程学院,山东青岛266590

出　　处：《中南大学学报（自然科学版）》2023年第6期2473-2481,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(51974171);山东省自然科学基金资助项目(ZR2019QEE015);山东省自然科学基金重大基础研究项目(ZR2019ZD13)。

摘　　要：为了分析不同约束刚度差异性对岩体点触探特性的影响,通过理论分析和数值分析修正给出以应变状态为标准的约束刚度差异性表征方法,并通过室内试验研究不同约束刚度对岩体点触探测试的影响。研究结果表明:在不同孔径和试样尺寸条件下,点触探压头下方拉伸应变不同,表明各条件下岩体结构的约束刚度存在差异性,原位钻孔条件下触探岩体的约束刚度最大,原位半空间条件下的其次,有限试样条件下触探岩体的约束刚度最小。若有限试样尺寸越大,则触探岩体的约束刚度越大;若原位钻孔孔径越小,则触探岩体的约束刚度越大。不同约束刚度对岩石点触探特性有重要影响。对于不同的约束刚度条件,试样初次破裂之前,其荷载-位移曲线斜率基本保持一致,随着约束刚度提高,试样的初次破裂位移与荷载逐渐提高;初次破裂后,点触探加载刚度弱化逐渐减小,最终试样破坏荷载逐渐增加。基于试验得到的初次破裂荷载比与本文给出的约束刚度比有较好的一致性,因此,通过横向拉伸应变条件定义的约束刚度比能够对刚度影响下的点触探指标进行合理表征。In order to characterize and analyze the influence of different constraint stiffness on the cone penetration characteristics of rock mass,the constraint stiffness characterization method was proposed through theoretical and numerical analyses,and the influence of different constraint stiffness on the cone penetration test was studied through laboratory tests.The results show that the tensile strain under the cone penetration indenter changes for different boreholes and sample sizes,which indicates the difference in constraint stiffness for different rock structures.The constraint stiffness of the rock mass under in-situ borehole condition is the largest,followed by that under the semi-infinite space condition,and the constraint stiffness of the rock mass under limited sample condition is the smallest.The larger the sample size,the higher constraint stiffness of the rock mass.The smaller the borehole diameter,the higher constraint stiffness of the rock mass.The constraint stiffness has an important influence on the rock point penetration characteristics.For different constraint stiffness conditions,the slope of load-displacement curve is basically consistent before the initial fracture of the specimen.With the increase of constraint stiffness,the initial fracture displacement and load of the specimen gradually increase.After the initial fracture,the weaken effect decreases with the increase of constraint stiffness.The initial fracture load ratio based on the test is consistent with the constraint stiffness ratio given in this paper,and so the constraint stiffness ratio defined by the tensile strain can be used to characterize the cone penetration index reasonably under the influence of constraint stiffness.

关 键 词：钻孔点触探测试 约束刚度 岩石力学 FRP约束 

分 类 号：TU45[建筑科学—岩土工程]