深部岩体变形模量数值反演计算方法及敏感性分析

Numerical inversion and sensitivity analysis of deformation modulus for deep rock mass

岩体变形模量是地下岩石工程设计和建造的关键参数之一。获取准确的岩体变形模量对深入分析深部岩体工程围岩变形行为至关重要。基于此,系统梳理归纳了常用的岩体变形模量计算方法,并利用有限元方法模拟原位试验进行岩体变形模量反演计算,与原位试验结果进行对比验证分析。针对深竖井实际工程,建立了深部地层不同岩性岩体变形模量反演分析数值计算模型,开展了不同强度准则、泊松比和岩体黏聚力对岩体变形模量的敏感性分析,将数值模拟反演结果与经验公式计算结果进行对比分析和讨论。研究结果表明,基于刚性平板载荷试验计算得到的岩体变形模量值与有限元数值反演得到的数值高度接近,具有较好的一致性;虽然泊松比对岩体变形模量有一定影响,但总体上岩体变形模量对泊松比的敏感性较低;当岩体黏聚力较小时,强度准则的选择对变形模量的反演结果影响显著,随着岩体黏聚力的增大,强度准则的选择对变形模量反演结果的影响逐渐减小;对于不同深度岩性的地层,岩体变形模量对岩体黏聚力变化敏感性不同;通过数值反演求得的岩体变形模量和一些经验公式的计算结果具有很好的相关性。因此,深部岩体工程规划设计和开发过程中可综合运用数值模拟和经验公式进行岩体变形模量反演计算,进而在更大程度上保障工程的安全性和经济性。

Rock deformation modulus is one of the key parameters for the design and construction of underground rock engineering.Obtaining accurate rock deformation modulus is crucial for a comprehensive analysis of the deformation behavior of the surrounding rock in deep rock engineering.To achieve this goal,the commonly used methods for calculating rock deformation modulus are systematically sorted out and summarized.Furthermore,the rock deformation modulus is inverse-calculated by simulating in-situ tests using the finite element method,and the results are verified and analyzed by comparing them with the in-situ test results.For the actual project of deep shaft,a numerical calculation model is established to conduct an inversion analysis of rock deformation modulus of different lithologies in the deep strata.Additionally,a sensitivity analysis is performed on different strength criteria,Poisson's ratio and rock cohesion on rock deformationmodulus.Finally,the numerical simulation inversion results are compared and discussed with the empirical formulacalculation results.The results show that the values of rock deformation modulus obtained from numerical inversion usingfinite element method are in good agreement with those calculated based on the experimental rigid plate load test;WhilePoisson's ratio does have some influence on rock deformation modulus,the sensitivity of rock deformation modulus toPoisson's ratio is generally low;When the cohesion of the rock mass is small,the choice of strength criterion has a significantinfluence on the inversion results of deformation modulus,and vice versa;the sensitivity of the rock deformationmodulus to the changes of the rock cohesion varies depending on the depth and lithology of the strata;the deformationmodulus of the rock mass obtained by numerical inversion has a good correlation with some empirical equations.Therefore,the numerical simulation and empirical formulae are useful during planning,design and development of deep rockprojects to perform the inversion calculation of rock deformation modulus,thereby ensuring greater safety and economy.