张年学, 李守定, 盛祝平. 2018: 用抗剪强度参数估算抗拉强度的方法与问题讨论. 工程地质学报, 26(s1): 446-456. DOI: 10.13544/j.cnki.jeg.2018127
    引用本文: 张年学, 李守定, 盛祝平. 2018: 用抗剪强度参数估算抗拉强度的方法与问题讨论. 工程地质学报, 26(s1): 446-456. DOI: 10.13544/j.cnki.jeg.2018127
    ZHANG Nianxue, LI Shouding, SHENG Zhuping. 2018: THE METHOD FOR ESTIMATING TENSILE STRENGTH BY USING SHEAR STRENGTH PARAMETERS AND DISCUSSIONS. JOURNAL OF ENGINEERING GEOLOGY, 26(s1): 446-456. DOI: 10.13544/j.cnki.jeg.2018127
    Citation: ZHANG Nianxue, LI Shouding, SHENG Zhuping. 2018: THE METHOD FOR ESTIMATING TENSILE STRENGTH BY USING SHEAR STRENGTH PARAMETERS AND DISCUSSIONS. JOURNAL OF ENGINEERING GEOLOGY, 26(s1): 446-456. DOI: 10.13544/j.cnki.jeg.2018127

    用抗剪强度参数估算抗拉强度的方法与问题讨论

    THE METHOD FOR ESTIMATING TENSILE STRENGTH BY USING SHEAR STRENGTH PARAMETERS AND DISCUSSIONS

    • 摘要: 因为多数岩石具有各种结构面,岩石力学试验强度参数多是离散的,所以岩石力学试验获得的参数具有估算的性质。根据单轴压缩实验Mohr圆破裂面的法向压力为零、即是与轴向压力方向一致的破裂面,导出压力劈裂圆的抗拉强度公式,用该公式计算了14个岩土试验的抗拉强度,并与这些岩土的Brazil劈裂试验和直接拉伸试验的抗拉强度进行比较,其相对误差一般都在20%以内,从岩土试验参数离散性角度看,压力劈裂圆公式具有实用价值。讨论了拉应力圆在Mohr-Coulomb准则下的负轴方向实际上不存在0轴压下的单向拉伸、即对柱状试件不会发生圆周拉张破坏模式,所以ISRM建议的t=f(3)作图回归法、以及多种根据Mohr拉应力圆几何关系导出的其他公式计算法存在计算抗拉强度偏大问题。分析指出了与单轴压缩实验3种破坏模式相应的应力圆及其应力范围。

       

      Abstract: The strength parameters of rock mechanics test are mostly discrete because most rocks have various structural planes/interfaces, therefore the parameters obtained by the rock mechanics tests have the properties of estimation. For a uniaxial compression test the normal stress on failure surface, i.e. failure surface parallel to the axial stress, of the Mohr circle is zero, hence the tensile strength formula is derived for the compression splitting circle. The formula is then used to calculate tensile strength from 14 tests of rock and soil. And the results are compared with those of geotechnical Brazil splitting test and direct tensile test usually with a relative error within 20%.From the perspective of the discrete geotechnical parameters the compression splitting failure circle formula has its practical value. In fact, there is no lateral tension failure with zero compression stress under the uniaxial compression in the negative axial direction of the Mohr-Coulomb criterion, namely no circumferential tensile failure mode happening for a cylindrical specimen. Therefore, the ISRM suggested sigma t=f(3) plotting regression method, and a variety of Mohr stress circle based on geometric relations always have errors for calculating tensile strength. The stress cycle and its stress range of three kinds of failure modes with uniaxial compression are further analyzed.

       

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