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为分析含水率和围压对泥岩峰后力学特性的影响,从山西安家岭矿取泥岩,制成不同含水率的5组试样,在YAW2000电液伺服试验机上开展了三轴试验,获得了不同含水率泥岩试样三轴全程应力应变曲线,使用激光共聚焦显微镜观测了泥岩增水过程中微观结构变化。利用试验结果,分析了围压和含水率对泥岩峰值强度、残余强度、弹性模量、破坏应变和脆性模量的影响规律和泥岩增水过程中微观结构的变化规律。引入脆性模量系数和强度退化指数来描述围压对泥岩峰后强度退化过程和残余强度的影响,与FLAC中的SS模型结合,建立了考虑围压影响的泥岩应变软化力学模型,模拟了围压对泥岩应变软化行为的影响。研究结果表明:(1)随着围压增加,泥岩的峰值强度、偏应力峰值、破坏应变和残余强度都增长,峰后强度降低速率趋缓,强度退化指数和脆性模量系数可以较好地描述围压对泥岩残余强度和峰后强度退化过程的影响。(2)泥岩增水过程中,岩样内微裂隙及尺寸增长,泥岩的力学性质劣化。随着含水率增加,泥岩的弹性模量、峰值强度和残余强度降低,破坏应变增长。含水率与泥岩的弹性模量、峰值强度和破坏应变之间近似服从线性关系。(3)本文基于脆性模量系数的岩石应变软化模型能较好地描述三轴压缩泥岩的全程变形行为。
In order to analyze the influence of water content and confining pressure on the mechanical characteristics of mudstone after peak, five samples with different water content were made from mudstone in Anjialing Mine, Shanxi Province. Triaxial tests were carried out on YAW2000 electro-hydraulic servo testing machine. The stress and strain curves of mudstone samples with different water contents during the whole triaxial compression were observed. The changes of microstructure during the increase of mudstone were observed by laser scanning confocal microscopy. The influence of confining pressure and water content on the peak strength, residual strength, elastic modulus, failure strain and brittleness modulus of mudstone and the variation regularity of the microstructure in the process of mudstone enrichment were analyzed by using the test results. The influence of confining pressure on post-peak strength degradation process and residual strength of mudstone is described by introducing the modulus of brittleness and strength degradation index. Combined with the SS model in FLAC, the strain-softening mechanical model of mudstone considering influence of confining pressure is established. Effect of pressure on strain softening behavior of mudstone. The results show that: (1) As the confining pressure increases, the peak strength, peak value of deviatoric stress, failure strain and residual strength of mudstone increase, and the rate of post-peak strength reduction slows down. The strength degradation index and brittle modulus coefficient can be better Describe the influence of confining pressure on the residual strength and post-peak strength degradation of mudstone. (2) During the increase of mudstone, the micro-fissures and sizes in the rock samples increase, and the mechanical properties of mudstone deteriorate. With the increase of water content, the elastic modulus, peak strength and residual strength of mudstone decrease, and the strain growth is destroyed. The relationship between water content and elastic modulus of mudstone, peak strength and failure strain is approximately linear. (3) The rock strain softening model based on brittle modulus coefficient can describe the whole deformation behavior of triaxial compression mudstone well.