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原岩应力状态是地下工程开挖的重要设计参数,它由主应力的大小和方向确定。通常的原岩应力测试方法,如套芯法,都只能得到小范围内的测量资料,且费用很大。本文介绍了一种大范围岩体的地下洞室应力测试方法,这是一种典型的区域应力测量方法。该法要求测出洞室开挖所引起的应力变化。通过把实测应力变化同理论预测的应力变化进行比较而拟合出原岩应力场。通过在两组应力变化值之间得出一个误差函数,使误差趋于极小而求解。本文通过一个具收敛解的圆形洞室的实例来阐述这种方法及其应用。工程实例研究表明,该法具有很大的潜在优势。所得反分析值与大量套芯法实测值相当一致。与常规方法相比,这种新方法有如下优点:(1)应力资料可在工程进展中随时得到校正;(2)测得的是大范围岩体而不是某个点的应力状态;(3)最重要的是费用相对较低。
The stress state of the original rock is an important design parameter for the excavation of underground engineering, which is determined by the magnitude and direction of the principal stress. Usually the original rock stress test methods, such as the core method, can only obtain small-scale measurement data, and the cost is very high. This paper describes a method for testing stress of underground caverns in a wide range of rock masses, which is a typical regional stress measurement method. The law requires measuring the stress changes caused by the excavation of a cavern. The original rock stress field was fitted by comparing the measured stress change with the theoretically predicted stress change. By solving an error function between two sets of stress changes, the error tends to be minimal. This paper illustrates this method and its application through an example of a circular solution with a convergent solution. Project case studies show that this method has great potential advantages. The resulting back analysis values are quite consistent with the actual measured values of a large number of core-insert methods. Compared with the conventional method, this new method has the following advantages: (1) The stress data can be corrected at any time during the progress of the project; (2) the stress state of a large range of rock masses rather than a certain point is measured; (3) ) The most important is the relatively low cost.