三峡花岗岩劈裂抗拉特性与弹性模量关系的研究

STUDY ON RELATIONSHIP BETWEEN SPLITTING BEHAVIOUR AND ELASTIC MODULUS OF THREE GORGES GRANITE

采用三峡花岗岩在伺服试验机上进行了劈裂拉伸全过程试验,发现试样破坏前加载力与加载点位移存在着明显的线性关系。认为这一线性特征体现了岩石弹性特征,因此可从加载力-加载点位移全过程曲线上直线段的性质来推算岩石的弹性模量。定义了劈裂模量,经过大量的劈裂抗拉和单轴抗压对比试验,提出三峡花岗岩的弹性模量与劈裂模量二者的经验比值为19.2。最后,通过三维有限元数值试验,从理论上证明了加载力与加载点位移之间存在着正比例关系,并指出二者的比例系数与岩石的弹性模量和试样的几何尺寸有关。

By Brazilian tension tests of complete procedure for Three Gorges granite conducted by a servo-controlled testing machine, it is found that there exists obvious linear relationship between load and displacement of load point before breakage. It is believed that the relationship demonstrates the elastic character of rock and therefore the elastic modulus of rock can be estimated from the complete load-displacement curve. The splitting modulus in Brazilian tension test was defined. Based on large quantity of Brazilian tension tests and uniaxial compression tests, the ratio of elastic modulus to splitting modulus of the Three Gorges granite is estimated as 19.2. Finally, the proportional relationship between load and displacement of load point is numerically simulated by 3D FEM. It is pointed out that the relationship is also affected by the elastic modulus and geometry of rock specimen.