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本文提出验算土石坝拉伸、开裂、剪切破坏安全性的一种实用的简便的方法。这方法适用于初步设计的初期阶段以及坝的施工期和运行期。因为在这些阶段不需要用有限单元法计算整个坝的应变和应力,只要分析坝的一些可疑部位的抗裂、抗剪切破坏的安全性。在初步设计的初期阶段,某些部位的位移竖直分量(沉陷)计算出来以后,另外两个分量可由经验参数“位移比”乘竖直分量得到。在坝的施工期和运行期,某些部位的三个位移分量由观测资料得到。这样,就可以用几何方程由位移计算主应变,再用非线性弹性增量方程式求主应力。由于坝表面处于单向应力状态,故用单轴拉伸试验成果检验其抗裂安全性。而坝体内部应力应变是二维或三维问题,故用三轴抗裂试验成果检验脆性开裂的安全性,用三轴剪切试验成果检验剪切破坏的安全性。最后举了一个例题说明计算和检验的步骤。
This paper presents a practical and simple method for checking the safety of tension, cracking and shear failure of earth-rock dams. This method is suitable for the initial stages of preliminary design as well as the construction and operation of the dam. Because it is not necessary to use the finite element method to calculate the strain and stress of the entire dam at these stages, only the safety of the anti-crack and anti-shear damages of some suspected areas of the dam is analyzed. At the initial stage of preliminary design, after the vertical component of displacement (subsidence) is calculated for some parts, the other two components can be obtained by multiplying the empirical parameter “displacement ratio” by the vertical component. During the construction period and the operation period of the dam, the three displacement components of some parts are obtained from observation data. In this way, the principal strain can be calculated from the displacement using a geometric equation, and then the principal stress can be obtained using a non-linear elastic incremental equation. As the dam surface is in a one-way stress state, the crack resistance safety is tested using the uniaxial tensile test results. The stress and strain inside the dam is a two-dimensional or three-dimensional problem, so the safety of the brittle cracking is verified by the results of the triaxial cracking test, and the safety of the shear failure is verified by the triaxial shear test results. Finally, an example is given to illustrate the calculation and verification steps.