卸荷岩体力学参数劣化规律的细观损伤分析

Mechanics parameters deterioration laws of unloading rock mass by meso-damage mechanics

基于细观损伤力学和卸荷岩体力学理论,以铜坑矿92号矿体连续卸荷开挖试验采场岩体力学参数为初始值,运用RFPA软件,建立岩体卸荷计算的等效数值模型,并对分步连续卸荷进行计算,研究岩体卸荷破坏过程和声发射效应,得到卸荷岩体力学参数的变化曲线以及卸荷岩体力学参数的劣化规律。研究结果表明:卸荷第19步即卸荷量为3.8 MPa时,岩体发生破坏失稳;在卸荷过程中,岩体力学参数均呈逐渐弱化的趋势,其中内摩擦角、黏聚力和弹性模量随卸荷的推进逐渐减小,最终值分别相当于初始值的54%,50%和52%;泊松比则逐渐增大,最终值相当于初始值的1.16倍。这表明卸荷效应劣化了岩体力学参数,得到的卸荷岩体力学参数劣化规律拟合曲线和方程为采动卸荷力学响应的动态分析提供了依据。

Based on the meso-damage mechanics and unloading mechanics theories, the mechanics parameters of test stops on continuous mining pit No.92 was taken as initial values, and the equivalent model of rock mass unloading was established by RFPA software. By calculating the step and continuous unloading of the equivalent model, the failure process and acoustic admission effect were studied, and the change curves and deterioration laws of unloading rock mass mechanics parameters were obtained. The result shows that by the unloading step 19, the unloading stress is 3.8 MPa, and the rock mass shows damage. The rock mechanical parameters, i.e. the internal friction angle, cohesion and the modulus of elasticity, show a gradual weakening trend, and the values are gradually decreased to 54%, 50% and 52% of the initial value. Poisson＇s ratio is gradually increased to the 1.16 times of the initial value. The rock mass mechanical parameters are deteriorated by unloading effect. The theoretical basis of dynamic analysis for mining mechanics response is provided by the fitted curves and of unloading rock mass mechanical parameters function of deterioration laws.