脆性岩石扩容起始应力预测——以花岗岩和闪长岩为例

 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。

PREDICTION OF INITIATION STRESS OF DILATION OF BRITTLE ROCKS

The Servo-controlled triaxial rock testing system TAW–2000 was used to obtain the characteristic mechanical parameters of 32 group of rock samples of granite and diorite. The relationships of the initiation stress of dilation(crack damage stress) with the elastic modulus，Poisson?s ratio and the porosity were established resulting in a simplified model for crack damage stress. The elastic modulus is a measure of overall rock stiffness including the stiffness of grain to grain contacts and the intergranular matrix. The porosity is a measure of void space in the rock consisting primary of fissures，pores and open cracks. They are both closely related to the initiation stress of rock dilation. The initiation stress of dilation is correlated positively with the elastic modulus，and negatively with the porosity. A mathematical model for the initiation stress of dilation was obtained through data fitting the test results. The model can be used to calculate the initiation stress of dilation once the elastic modulus，the porosity and Poisson's ratio are known.