A comparative study for determining rock joint normal stiffness with destructive uniaxial compression and nondestructive ultrasonic wave testing  

作　　者：Zhenghu Zhang Jianbo Zhu Jianhui Deng 

机构地区：[1]School of Civil Engineering,Dalian University of Technology,Dalian,116024,China [2]Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Hong Kong,China [3]Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,College of Civil and Transportation Engineering,Shenzhen University,Shenzhen,518060,China [4]State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resources and Hydropower,Sichuan University,Chengdu,610065,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2023年第7期1700-1712,共13页岩石力学与岩土工程学报（英文版）

基　　金：supported by the Shenzhen Fundamental Research Program(Grant No.JCYJ20220818095605012);the National Natural Science Foundation of China(Grant No.51909026);the Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization(Grant No.2020-08).

摘　　要：Rock joints are one of the vital discontinuities in a natural rock mass.How to accurately and conveniently determine joint normal stiffness is therefore significant in rock mechanics.Here,first,seven existing methods for determining joint normal stiffness were introduced and reviewed,among which MethodⅠ(the indirect measurement method),MethodⅡ(the direct determination method),MethodⅢ(the across-joint strain gauge measurement method)and MethodⅣ(the deformation measuring ring method)are via destructive uniaxial compression testing,while MethodⅤ(the best fitting method),MethodⅥ(the rapid evaluation method)and MethodⅦ(the effective modulus method)are through wave propagation principles and nondestructive ultrasonic testing.Subsequently,laboratory tests of intact and jointed sandstone specimens were conducted following the testing requirements and pro-cedures of those seven methods.A comparison among those methods was then performed.The results show that Method I,i.e.the benchmark method,is reliable and stable.MethodⅡhas a conceptual drawback,and its accuracy is acceptable at only very low stress levels.Relative errors in the results from MethodⅢare very large.With MethodⅣ,the testing results are sufficiently accurate despite the strict testing environment and complicated testing procedures.The results from MethodⅤare greatly unstable and significantly dependent on the natural frequency of the transducers.The joint normal stiffness determined with MethodⅥis stable and accurate,although data processing is complex.MethodⅦcould be adopted to determine the joint normal stiffness corresponding to the rock elastic deformation phase only.Consequently,it is suggested that MethodsⅠ,ⅣandⅥshould be adopted for the mea-surement of joint normal stiffness.The findings could be helpful in selecting an appropriate method to determine joint normal stiffness and,hence,to better solve discontinuous rock mass problems.

关 键 词：Normal stiffness Rock joint Uniaxial compression Ultrasonic wave 

分 类 号：TU45[建筑科学—岩土工程]