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通过分析盐岩在三轴应力状态下的变形,说明了较高围压下盐岩的大变形特性,提出了三轴应力状态下,利用轴向荷载除以试件初始横截面面积得到应力-应变关系存在的问题,据此对工程应变和对数应变进行了分析和对比,阐明了这两种应变的适用条件,并开展了不同围压下的试验测试和对试验结果对比分析。研究揭示了应利用对数应变分析盐岩的大变形特性和对变形后的应力进行修正,得到了盐岩的工程应变和对数应变均可表示为围压的线性函数,围压为20 MPa时的轴向压缩变形量是5 MPa时的3.09倍。围压越高,对数应变修正得到的最大轴向应力与不修正的差值越大,用对数应变修正后的轴向应力低于不修正的结果,围压达到20 MPa时,前者仅为后者的63.85%。
By analyzing the deformation of rock under triaxial stress, the large deformation characteristics of rock salt under high confining pressure are described. Under triaxial stress state, the axial load is divided by the initial cross-sectional area of specimen to obtain the stress- According to the analysis and comparison of engineering strain and logarithmic strain, the applicable conditions of these two kinds of strain are clarified, and the test under different confining pressures and the comparative analysis of test results are carried out. The study revealed that large deformation of rock salt should be analyzed by logarithmic strain and the stress after deformation should be corrected. The engineering strain and logarithmic strain of salt rock can be expressed as a linear function of confining pressure. The confining pressure is 20 MPa When the axial compression deformation is 3.09 times when 5 MPa. The higher the confining pressure, the greater the difference between the maximum axial stress and the uncorrected value obtained from the logarithmic strain correction. The axial stress corrected with the logarithmic strain is lower than the uncorrected result. When the confining pressure reaches 20 MPa, the former only 63.85% for the latter.