非贯通裂隙软岩单轴压缩强度特征及贯通机制研究

为了解非贯通裂隙软岩单轴压缩强度特征及其贯通机制,以非贯通裂隙软岩试样为研究对象,进行单轴压缩破坏试验,得到不同裂隙排数、倾角及贯通深度条件下非贯通裂隙软岩试样的强度特征,对破坏试样的裂纹和破坏面进行分析,得到非贯通裂隙软岩试样的裂纹类型和贯通机制。不同裂隙特征参数条件下的对比研究成果表明:不同裂隙排数及贯通深度的非贯通裂隙试样均以30°倾角试样强度为最低,这与贯通裂隙试样存在差异。分析不同裂隙排数及贯通深度的非贯通裂隙试样的强度参数,发现30°倾角试样的黏聚力最低,只有完整岩样黏聚力的43.53%;而倾角相同时,不同裂隙排数的试样强度均随裂隙贯通深度的增加而降低。受荷条件下裂隙间的多次贯通使得非贯通裂隙试样呈现出局部渐进破坏特征,扩展裂纹以次生裂纹为主,翼裂纹初期发育后逐渐停止扩展。裂隙排数对试样贯通机制起主导作用,单排裂隙基本以Ⅰ型张拉破坏为主(60°倾角试样除外),而双排裂隙则以Ⅱ型剪切破坏为主。研究成果对解决实际工程中遇到的破裂岩体强度计算问题和破坏机制问题具有参考价值。

Study on uniaxial compressive strength characteristics and penetration mechanism of soft rock with non-penetrative joints

In order to find out the uniaxial compressive strength characteristics and the penetration mechanism of the soft rock with non-penetrative joints，an experiment of uniaxial compressive failure is made by taking the sample of the soft rock with nonpenetrative joints as the study object，and then different row numbers and dip-angles of the fissures as well as the strength characteristics of the sample of the soft rock with non-penetrative joints under the condition of the penetration depth are obtained， while the fissures and failure planes of the sample are analyzed，thus the fissure types and penetration mechanism of the soft rock sample with non-penetrative joints are acquired. The result from the comparative study made under the condition of different parameters of fissure characteristics shows that within the non-penetratively jointed samples with different row numbers and penetration depths，the strengths of all the samples with the dip-angle of 30° are the lowest，which differ from those from the penetratively jointed samples. Through the analysis of the strength parameters of the non-penetratively jointed samples with different row numbers and penetration depths，It is found out that the cohesive force of the sample with the dip-angle of 30° is the lowest， which is only 43. 53% of the cohesive force of the integral rock sample，while the strengths of all the samples with different row number of fissure are decreased along with the increases of the fissure penetration depth，if the dip-angles are the same. The penetrations for many times among the fissures under load condition make the samples with non-penetrative fissures exhibit the characteristics of the local-progressive failure，while the extensive fissures are mainly the secondary fissures，of which the extensions are to be gradually stopped after the initial developments of the wing fissures. The row number of fissure plays a dominant role on the penetration mechanism of the sample，i. e. the single-row fissures( except the sample with the dip-angle of 60°) are mainly dominated by the tensile failure of Type I，while the dual-row fissures are mainly dominated by the shear failure of Type II. The study result has a referential value for solving the problems from the strength calculation and failure mechanism of fractured rock mass during the actual construction.