Study on back analysis of rock mechanical parameters based on the digital control rock indentation equipment
LI Yiming1，ZHAO Gaofeng1，ZHAO Xiaobao2，LI Haibo3
(1. State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300072，China；2. School of Earth Sciences and Engineering，Nanjing University，Nanjing，Jiangsu 210093，China；3. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：To obtain the distribution of rock mechanical parameters，a rock indentation equipment was developed based on the digital control three-dimensional platform，and a parameter acquisition method based on this equipment was proposed. The correction formula of the load-displacement curve for the testing machine was established by integrating different indentation tests with the refined three-dimensional numerical simulation and considering the effect of the test procedure and frame stiffness. Then，a large number of numerical simulations and parameter sensitivity analysis for this equipment were conducted，and the classical Oliver-Pharr formula was improved to precisely determine the elastic parameter of rocks. The results indicated that there was a great difference between the estimated elastic modulus by the classical Oliver-Pharr formula and measured values. The proposed improved Oliver-Pharr formula gave a better performance in predictions of the elastic modulus for three types of rocks，with relative errors of 5.83%(granite)，5.14%(marble) and 10.79%(sandstone)，respectively. Moreover，the plastic parameter of rocks was determined based on the indentation test by establishing the relationship between the cohesive and the plastic region area(S) and the difference between the unloading stiffness and the secant stiffness of the loading phase(Kp)，respectively. Compared the results with the measured cohesion by the experimental test，we found that the formula of stiffness difference based on the M-C model gave a better performance in estimating the cohesion of rocks，with relative errors of 17.81%(marble) and 21.93%(sandstone)，respectively. Moreover，the discussion was conducted in terms of the acquisition of the spatial parameter fields of rocks and rock damage based on the testing device. The results of this research presented an efficient approach to obtain rock mechanical parameters fields and provided support for the parameter selection of the refined numerical simulation in rock mechanics.
李一鸣1，赵高峰1，赵晓豹2，李海波3. 基于数控岩石压痕试验装置的岩石力学参数反演研究[J]. 岩石力学与工程学报, 2023, 42(8): 1973-1987.
LI Yiming1，ZHAO Gaofeng1，ZHAO Xiaobao2，LI Haibo3. Study on back analysis of rock mechanical parameters based on the digital control rock indentation equipment. , 2023, 42(8): 1973-1987.
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2023, Vol. 42 
