王云飞, 宿辉, 王立平, 焦华喆, 李震. 3种砂岩变形与强度特征对比分析[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.0418
引用本文: 王云飞, 宿辉, 王立平, 焦华喆, 李震. 3种砂岩变形与强度特征对比分析[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.0418
WANG Yunfei, SU Hui, WANG Liping, JIAO Huazhe, LI Zheng. Study on the difference of deformation and strength characteristics of three kinds of sandstone[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.0418
Citation: WANG Yunfei, SU Hui, WANG Liping, JIAO Huazhe, LI Zheng. Study on the difference of deformation and strength characteristics of three kinds of sandstone[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.0418

3种砂岩变形与强度特征对比分析

Study on the difference of deformation and strength characteristics of three kinds of sandstone

  • 摘要: 为了明确3种砂岩力学行为的差异及产生差异的内在原因,利用RMT-150B岩石力学试验系统对3种砂岩进行了三轴试验,分析了3种砂岩的变形、强度和破坏特征。试验结果表明:白砂岩和红砂岩的屈服特征明显,塑性变形显著,随着围压的增大,屈服段逐渐增长,黄砂岩屈服特性不明显且受围压影响较小;砂岩的单轴抗压强度越高,围压对其强度的提高效应越显著,其中黄砂岩抗压强度受围压影响提高显著;砂岩弹性模量和变形模量受围压影响的提高程度与低围压时弹性模量和变形模量的大小成正比,且围压对黄砂岩弹性模量和变形模量的影响显著;3种砂岩的内摩擦角差值较大,而黏聚力相差较小,因而可见3种砂岩强度的差异主要是内摩擦角的不同导致的;砂岩的巴西劈裂强度为单轴抗压强度的3.5%~5.8%。3种砂岩的围压影响系数随围压增加整体按负指数关系减小,20 MPa是围压影响系数减小快慢的转折点;通过试验结果分析3种强度准则,指出幂函数Mohr强度准则能更好的反应不同围压岩石强度的非线性特征;白砂岩发生典型的缓倾角剪切破坏,破裂面为平面,红砂岩和黄砂岩在低围压下发生张剪复合破坏,在高围压时发生陡倾角剪切破坏,红砂岩的破裂面为锥面,黄砂岩的破裂面为高低不平的起伏面。

     

    Abstract: In order to clarify the differences and the intrinsic causes of mechanical behavior of three kinds of sand- stone,the conventional triaxial test for three kinds of sandstone were carried out by RMT-150B rock mechanics test system,and the deformation,strength and failure characteristics of three kinds of sandstone were analyzed. The results showed that the yield characteristics of white sandstone and red sandstone were obvious,and the plastic deformation were remarkable,with the increase of confining pressure,the yield stage increased gradually,while the yield character- istic of yellow sandstone was not obvious and less affected by confining pressure. The higher the uniaxial compressive strength of sandstone is,the more significant the effect of confining pressure on its strength is,and the effect of confining pressure on the compressive strength of yellow sandstone was remarkable. The improvement degree of elastic mod- ulus and deformation modulus of sandstone influenced by confining pressure is proportional to the magnitude of elastic modulus and deformation modulus under lower confining pressure,and the influence of confining pressure on elastic modulus and deformation modulus of yellow sandstone was significant. The difference of internal friction angle between the three kinds of sandstone was large,while the difference of cohesion was small. Therefore,the strength difference of the three kinds of sandstone is mainly caused by the difference of internal friction angle. Brazilian splitting strength of sandstone is 3. 5% -5. 8% of uniaxial compressive strength. The confining pressure influence coefficient of the three kinds of sandstone decreased in a negative exponential relationship with the increase of confining pressure,and 20 MPa is the turning point of speed change of the confining pressure influence coefficient. Three kinds of strength criteria were analyzed through the experimental data,it is pointed out that the strength function of Mohr strength criterion can better reflect the non-linear characteristics of rock strength under different confining pressures. The typical slow dip angle shear failure occurs in white sandstone,and its fracture plane is plane. the tension-shear composite failure of red sand- stone and yellow sandstone occurs under lower confining pressure,and steep dip angle shear failure occurs under high- er confining pressure,the fracture plane of red sandstone is conical,while that of yellow sandstone is uneven.

     

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