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采用TAW–2000电液伺服岩石三轴试验机,通过32组花岗岩和闪长岩的物性及单轴压缩试验测试,获得岩石的特征物理力学参数。在此基础上,揭示岩石扩容起始应力与弹性模量、泊松比和孔隙度的关系,建立花岗岩和闪长岩的扩容起始应力预测方程。研究结果表明:(1)弹性模量作为岩石的弹性基质刚度的反映,包括颗粒间的接触刚度和颗粒间基质的刚度,孔隙度作为岩石内部孔洞空间的体积测量指标,是岩石内初始的微裂纹、微孔洞及张开裂纹的综合反映,一定程度上可以反映初始损伤的程度,二者与岩石的扩容起始应力密切相关;(2)扩容起始应力与弹性模量呈正相关,而与孔隙度呈负相关,当弹性模量最小而孔隙度最大时对应最小的扩容应力值,反之调整;(3)通过逐步数据拟合分析得出扩容应力的预测模型,通过与试验结果的对比分析,证明预测模型的可靠性。在弹性模量、孔隙度和泊松比已知的前提下,可以先验地对扩容起始应力进行预测,为扩容起始应力的求解提供一条新的思路。
TAW-2000 electro-hydraulic servo rock triaxial testing machine was used to test the physical properties and uniaxial compression tests of 32 groups of granite and diorite to obtain the characteristic physical and mechanical parameters of the rock. On this basis, the relationship between the initial stress and modulus of elasticity, Poisson’s ratio and porosity of rock expansions is revealed, and the initial stress-expansion equation of granite and diorite is established. The results show that: (1) The elastic modulus is a reflection of the elastic matrix stiffness of rock, including the contact stiffness between particles and the stiffness of intergranular matrix. Porosity is the measure of the volume of pores in the rock. The comprehensive reflection of cracks, micropores and open cracks can reflect the degree of initial damage to a certain extent, and the two are closely related to the initial stress of rock expansion. (2) The initial stress of expansion is positively correlated with the elastic modulus And negatively correlated with the porosity. When the elastic modulus is the smallest and the porosity is the largest, it corresponds to the minimum expansion stress, and vice versa. (3) The prediction model of the expansion stress is obtained through stepwise data fitting analysis. By comparing with the experimental results Analyze and prove the reliability of the forecasting model. Under the premise of the known elastic modulus, porosity and Poisson’s ratio, the initial stress of expansion can be predicted a priori, providing a new idea for solving the initial stress of expansion.