杨秀荣, 姜谙男, 张峰瑞, 张权. 破裂石灰岩在渗透压-应力耦合作用下渗流特性研究[J]. 煤炭学报, 2019, 44(S1): 101-109. DOI: 10.13225/j.cnki.jccs.2019.0068
引用本文: 杨秀荣, 姜谙男, 张峰瑞, 张权. 破裂石灰岩在渗透压-应力耦合作用下渗流特性研究[J]. 煤炭学报, 2019, 44(S1): 101-109. DOI: 10.13225/j.cnki.jccs.2019.0068
YANG Xiurong, JIANG Annan, ZHANG Fengrui, ZHANG Quan. Seepage characteristics of fractured limestone under osmotic pressure-stress coupling[J]. Journal of China Coal Society, 2019, 44(S1): 101-109. DOI: 10.13225/j.cnki.jccs.2019.0068
Citation: YANG Xiurong, JIANG Annan, ZHANG Fengrui, ZHANG Quan. Seepage characteristics of fractured limestone under osmotic pressure-stress coupling[J]. Journal of China Coal Society, 2019, 44(S1): 101-109. DOI: 10.13225/j.cnki.jccs.2019.0068

破裂石灰岩在渗透压-应力耦合作用下渗流特性研究

Seepage characteristics of fractured limestone under osmotic pressure-stress coupling

  • 摘要: 为探讨不同围压作用下破裂岩石的渗透特性,选取吉林省甄峰岭隧道区石灰岩为研究对象,利用多场耦合的岩石伺服三轴仪分析了不同围压作用下破裂石灰岩的渗透率随净围压以及渗透压的变化规律,研究了破裂石灰岩在围压加卸载过程中以及渗透水压变化过程中的渗透率变化。并对试验数据进行非线性拟合,得到破裂试样渗透率随净围压变化的关系式,又采用 FLAC3D内嵌 FISH 语言自编石灰岩裂隙渗流-应力耦合的计算程序,对破裂石灰岩不同裂隙角度的试样进行数值计算,计算值与试验值吻合较好。试验结果表明:① 围压越大,石灰岩的峰值强度越大,其中在高围压(20 MPa)下试样的峰值强度比在低围压(5 MPa)的峰值强度提高了69%; ② 轴压、渗透压一定时,破裂石灰岩的渗透率在围压加载阶段随着净围压的增大而减小,在卸载阶段有所恢复,但低于围压的加载阶段; ③ 轴压、围压一定时,渗透压增大,渗透率有所增加; ④ 试样破裂面的倾角随着围压的增大而减小,由低围压(5 MPa)的90°降为高围压(20 MPa)下的65°,破坏程度越来越严重,破坏状态由低围压下的脆性劈裂破坏向高围压下的韧性剪切破坏转变; ⑤ 试样破坏时围压越高,裂隙与水平夹角越小,水力开度增大,围压剪切作用导致裂隙渗透性越大。研究结果可为隧道工程中围岩渗透率的演化机制的研究提供参考。

     

    Abstract: In order to investigate the seepage characteristics of fractured rock under different confining pressures, the limestone in the Zhenfengling tunnel area of Jilin Province was selected as the research object.The multi-field coupled rock servo triaxial apparatus was used to analyze the variation of the permeability of the fractured limestone with the net confining pressure and osmotic pressure under different confining pressures.The nonlinearity fitting of the experimental data was carried out to obtain the relationship between the permeability of the fractured specimen and the change of the net confining pressure.Besides, the calculation procedure of the limestone fracture seepage-stress coupling in the FLAC3D embedded FISH language was used for the numerical calculation of spec-imens with different fracture angles of fractured limestone.The test results show that ① the larger the confining pressure is, the higher peak strength the limestone has, and the peak strength of the sample at high confining pressure (20 MPa) is 69% higher than the peak strength at low confining pressure (5 MPa).② When the axial pressure and osmotic pressure are constant, the permeability of the fractured limestone decreases with the increase of the net confining pressure during the confining pressure loading phase, and recovers during the unloading phase, but lower than the confining pressure loading phase.③ When the axial pressure and confining pressure are constant, the permeability increases when the osmotic pressure increases.④ The inclination angle of the fracture surface of the sample decreases with the increase of confining pressure, from 90° at low confining pressure (5 MPa) to 65° at high confining pressure (20 MPa), and the fracture degree becomes more and more serious.The failure state is changed from brittle fracture under low confining pressure to ductile shear failure under high confining pressure.⑤ The higher the confining pressure when the sample is destroyed, the smaller the angle between the crack and the horizontal, the greater the hydraulic opening, and the greater the permeability of the crack caused by the confining shear.The research results can provide some reference values for the study of the evolution mechanism of surrounding rock permeability in tunnel engineering.

     

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