地壳上部岩体中水平应力的估算方法

Evaluation Method of the Horizontal Stresses Range in the Earth's Upper Crust

地壳上部岩体的垂直应力一般可用其上覆岩体的平均比重乘以其深度来估算,但是水平应力却很难估算。岩体的断裂韧度是一个常数,如果裂隙岩体是稳定的,水平应力必须在一定的范围内,如果水平应力超过了这一范围,岩体内的裂隙可能会发生扩展、破坏,并可能导致地震的发生,因此从裂隙岩体稳定的条件出发,可以估算出水平应力的范围。利用一共线双裂纹模型建立了裂纹稳定的应力条件,并对该应力条件的有效性进行了实验验证,实验结果表明该应力条件是有效的;然后利用该应力条件来估算水平应力的范围,其结果符合现场的测试结果,表明这一估算方法是有效的,可行的。并利用该理论能很好地解释为什么水平应力与垂直应力之比在浅部地壳中分布在较宽的范围内,但在深部区域内却分布在一个狭小的范围内。

In order to solve the problem that in the underground rock mass,the horizontal stress is difficult to be estimated,a crack stable condition based on a model with two collinear cracks was established,and validated by experiments.The results showed that the crack stable condition is effective.By using this condition,the range of horizontal stress was evaluated,and the results agreed well with the in-situ measurement results.Finally,the phenomeon that the ratio of horizontal stress to vertical stress is scattered in a wide range near the underground surface,but scattered in a narrow range in the deep zone,was explained well by this result.