不同卸荷路径对砂岩渗透性演化影响的试验研究
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摘要
为了研究初始围压和卸荷速率对砂岩卸荷变形破坏过程中渗透性演化规律的影响,开展考虑不同初始围压(10,20,30 MPa)、不同卸荷速率(0.1,0.5,1.0,1.5 MPa/min)下的三轴卸荷渗流力学试验研究。研究结果表明:(1)砂岩卸荷破坏时表现为明显脆性特征,且随初始围压和卸荷速率的增大,砂岩侧向变形和体积扩容特性愈加明显。(2)砂岩卸荷破坏过程中渗透率演化规律与卸荷应力–应变关系密切相关,呈现阶段性变化特征,即弹性变形阶段渗透率增长缓慢;屈服变形阶段渗透率加速增长;达到卸荷峰值应力后,进入应力跌落阶段,此时渗透率急剧增长,并发生突跳现象;卸荷破坏后残余强度阶段,渗透率快速下降并趋于稳定。(3)不同初始围压和卸荷速率对砂岩卸荷变形破坏过程中渗透性演化影响明显,初始卸荷围压越高,卸荷破坏时的卸荷量越大,但卸荷量与初始围压比值越小;卸荷速率越大,砂岩卸荷破坏时产生的卸荷量越大,所处围压水平越低,渗透率峰值越高。研究成果可为深埋地下岩石工程围岩渗透性演化与安全评价提供参考。
In order to study the influence of the initial confining pressure and the unloading rate on permeability evolution of sandstone during unloading process,triaxial unloading seepage tests were carried out under different high initial confining pressures(10,20,30 MPa) and different unloading rates(0.1,0.5,1.0,1.5 MPa/min). The results show that the sandstone occurs brittle failure and that the lateral deformation and the volume expansion increase significantly with increasing the initial confining pressure or the unloading rate. The permeability evolution is closely related to the unloading stress and strain characteristics. The permeability increases slowly at the elastic deformation stage,rapidly at the yield deformation stage and sharply at the stress dropping stage,and eventually decreases to a stable value at the residual strength stage. The initial confining pressure and the unloading rate have a significant influence on the permeability evolution of sandstone. With increasing the initial confining pressure,the variation of the unloading pressure from the beginning of unloading to the moment of failure increases while the ratio between the final and initial confining pressures decreases. With ascending the unloading rate,the variation of the unloading pressure increases and the peak value of the permeability increases due to a lower confining pressure at failure. The results could provide a good reference for permeability and safety evaluation of surrounding rocks in deep underground rock engineering.
In order to study the influence of the initial confining pressure and the unloading rate on permeability evolution of sandstone during unloading process,triaxial unloading seepage tests were carried out under different high initial confining pressures(10,20,30 MPa) and different unloading rates(0.1,0.5,1.0,1.5 MPa/min). The results show that the sandstone occurs brittle failure and that the lateral deformation and the volume expansion increase significantly with increasing the initial confining pressure or the unloading rate. The permeability evolution is closely related to the unloading stress and strain characteristics. The permeability increases slowly at the elastic deformation stage,rapidly at the yield deformation stage and sharply at the stress dropping stage,and eventually decreases to a stable value at the residual strength stage. The initial confining pressure and the unloading rate have a significant influence on the permeability evolution of sandstone. With increasing the initial confining pressure,the variation of the unloading pressure from the beginning of unloading to the moment of failure increases while the ratio between the final and initial confining pressures decreases. With ascending the unloading rate,the variation of the unloading pressure increases and the peak value of the permeability increases due to a lower confining pressure at failure. The results could provide a good reference for permeability and safety evaluation of surrounding rocks in deep underground rock engineering.
引文
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[8]俞缙,李宏,陈旭,等.渗透压-应力耦合作用下砂岩渗透率与变形关联性三轴试验研究[J].岩石力学与工程学报,2013,32(6):1 203-1 213.(YU Jin,LI Hong,CHEN Xu,et al.Triaxial experimental study of associated permeability-deformation of sandstone under hydro-mechanical coupling[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(6):1 203-1 213.(in Chinese))
[9]俞缙,李宏,陈旭,等.砂岩卸围压变形过程中渗透特性与声发射试验研究[J].岩石力学与工程学报,2014,33(1):69-79.(YU Jin,LI Hong,CHEN Xu,et al.Experimental study of permeability and acoustic emission characteristics of sandstone during processes of unloading confining pressure and deformation[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(1):69-79.(in Chinese))
[10]CHEN X,TANG C A,YU J,et al.Experimental investigation on deformation characteristics and permeability evolution of rock under confining pressure unloading conditions[J].Journal of Central South University,2018,25(8):1 987-2 001.
[11]王伟,郑志,王如宾,等.不同应力路径下花岗片麻岩渗透特性的试验研究[J].岩石力学与工程学报,2016,35(2):260-267.(WANG Wei,ZHENG Zhi,WANG Rubin,et al.Experimental study of permeability properties of granitc gneiss under different stress paths[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):260-267.(in Chinese))
[12]WU G,ZHANG L.Studying unloading failure characteristics of a rock mass using the disturbed state concept[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(3):437-437.
[13]ZHAO X G,WANG J,CAI M,et al.Influence of unloading rate on the strain burst characteristics of beishan granite under true-triaxial unloading conditions[J].Rock Mechanics and Rock Engineering,2014,47(2):467-483.
[14]李建林,王瑞红,蒋昱州,等.砂岩三轴卸荷力学特性试验研究[J].岩石力学与工程学报,2010,29(10):2 034-2 041.(LI Jianlin,WANG Ruihong,JIANG Yuzhou,et al.Experimental study of sandstone mechanical properties by unloading triaxial tests[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(10):2 034-2 041.(in Chinese))
[15]黄润秋,黄达.卸荷条件下岩石变形特征及本构模型研究[J].地球科学进展,2008,23(5):441-447.(HUANG Runqiu,HUANG Da.Study on deformation characteristics and constitutive model of rock on the condition of unloading[J].Advances in Earth Sciences,2008,23(5):441-447.(in Chinese))
[16]黄润秋,黄达.高地应力条件下卸荷速率对锦屏大理岩力学特性影响规律的试验研究[J].岩石力学与工程学报,2010,29(1):21-33.(HUANG Ronqiu,HUANG Da.Experimental research oil affection laws of unloading rate on mechanical properties of Jinping marble under high geostress[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(1):21-33.(in Chinese))
[17]邓华锋,王哲,李建林,等.卸荷速率和孔隙水压力对砂岩卸荷特性影响研究[J].岩土工程学报,2017,39(11):1 976-1 983.(DENG Huafeng,WANG Zhe,LI Jianlin,et al.Effect of unloading rate and pore water pressure on mechanical properties of sandstone[J].Chinese Journal of Geotechnical Engineering,2017,39(11):1 976-1 983.(in Chinese))
[18]邱士利,冯夏庭,张传庆,等.不同卸围压速率下深埋大理岩卸荷力学特性试验研究[J].岩石力学与工程学报,2010,29(9):1 807-1 817.(QIU Shili,FENG Xiating,ZHANG Chuanqing,et al.Different unloading confining pressure rate of deep buried marble unloading mechanical properties test and research[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(9):1 807-1 817.(in Chinese))
[19]韩铁林,师俊平,陈蕴生,等.轴、侧向同卸荷下砂岩力学特性影响的试验研究[J].力学学报,2016,48(3):936-943.(HAN Tielin,SHI Junping,CHEN Yunsheng,et al.Experimental study on mechanics characteristics of sandstone under axial unloading and radial unloading path[J].Chinese Journal of Theoretical and Applied Mechanics,2016,48(3):936-943.(in Chinese))
[20]刘新荣,刘俊,冯昊,等.不同初始卸荷水平和水压下砂岩卸荷力学特性试验研究[J].岩土工程学报,2018,40(6):1 143-1 151.(LIU Xinrong,LIU Jun,FENG Hao,et al.Experimental research on unloading mechanical properties of sandstone under different initial unloading levels and pore pressures[J].Chinese Journal of Geotechnical Engineering,2018,40(6):1 143-1 151.(in Chinese))
[21]梁宁慧,刘新荣,包太,等.岩体卸荷渗流特性的试验[J].重庆大学学报:自然科学版,2005,28(10):133-135.(LIANG Ninghui,LIU Xinrong,BAO Tai,et al.Experimental study on the characteristic of seepage with unloading rock mass[J].Journal of Chongqing University:Natural Science,2005,28(10):133-135.(in Chinese))
[22]DAVY C A,SKOCZYLAS F,BARNICHON J D,et al.Permeability of macro-cracked argillite under confinement:gas and water testing[J].Physics and Chemistry of the Earth:Parts A/B/C,2007,32(8/14):667-680.
[23]何满潮,谢和平,彭苏萍,等.深部开采岩体力学研究[J].岩石力学与工程学报,2005,24(16):2 803-2 813.(HE Manchao,XIEHeping,PENG Suping,et a1.Study on rock mechanics in deep mining engineering[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(16):2 803-2 813.(in Chinese))
[24]黄润秋,黄达.卸荷条件下花岗岩力学特性试验研究[J].岩石力学与工程学报,2008,27(11):2 205-2 213.(HUANG Runqiu,HUANG Da.Experimental study on mechanical properties of granite under loading conditions[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2 205-2 213.(in Chinese))
[2]唐春安,马天辉,李连崇,等.高放废料地质处置中多场耦合作用下的岩石破裂问题[J].岩石力学与工程学报,2007,26(增2):3 932-3 938.(TANG Chun′an,MA Tianhui,LI Lianchong,et al.Rock failure issues in geological disposal of high-level radioactive wastes under multi-field coupling function[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(Supp.2):3 932-3 938.(in Chinese))
[3]李宏哲,夏才初,闫子舰,等.锦屏水电站大理岩在高应力条件下的卸荷力学特性研究[J].岩石力学与工程学报,2007,26(10):2 104-2 109.(LI Hongzhe,XIA Caichu,YAN Zijian,et al.Study on marble unloading mechanical properties of Jinping hydropower station under high geostress conditions[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(10):2 104-2 109.(in Chinese))
[4]王伟,徐卫亚,王如宾,等.低渗透岩石三轴压缩过程中的渗透性研究[J].岩石力学与工程学报,2015,34(1):40-47.(WANG Wei,XU Weiya,WANG Rubin,et al.Permeability of dense rock under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(1):40-47.(in Chinese))
[5]ALAM A K M B,NIIOKA M,FUJII Y,et al.Effects of confining pressure on the permeability of three rock types under compression[J].International Journal of Rock Mechanics and Mining Sciences,2014,65(1):49-61.
[6]王环玲,徐卫亚,杨圣奇.岩石变形破坏过程中渗透率演化规律的试验研究[J].岩土力学,2006,27(10):1 703-1 708.(WANGHuanling,XU Weiya,YANG Shengqi.Experimental investigation on permeability evolution law during course of deformation and failure of rock specimen[J].Rock and Soil Mechanics,2006,27(10):1 703-1 708.(in Chinese))
[7]朱珍德,张爱军,徐卫亚.脆性岩石全应力-应变过程渗流特性试验研究[J].岩土力学,2002,23(5):555-559.(ZHU Zhende,ZHANGAijun,XU Weiya.Experimental research on complete stress-strain process seepage characteristics of brittle rock[J].Rock and Soil Mechanics,2002,23(5):555-559.(in Chinese))
[8]俞缙,李宏,陈旭,等.渗透压-应力耦合作用下砂岩渗透率与变形关联性三轴试验研究[J].岩石力学与工程学报,2013,32(6):1 203-1 213.(YU Jin,LI Hong,CHEN Xu,et al.Triaxial experimental study of associated permeability-deformation of sandstone under hydro-mechanical coupling[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(6):1 203-1 213.(in Chinese))
[9]俞缙,李宏,陈旭,等.砂岩卸围压变形过程中渗透特性与声发射试验研究[J].岩石力学与工程学报,2014,33(1):69-79.(YU Jin,LI Hong,CHEN Xu,et al.Experimental study of permeability and acoustic emission characteristics of sandstone during processes of unloading confining pressure and deformation[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(1):69-79.(in Chinese))
[10]CHEN X,TANG C A,YU J,et al.Experimental investigation on deformation characteristics and permeability evolution of rock under confining pressure unloading conditions[J].Journal of Central South University,2018,25(8):1 987-2 001.
[11]王伟,郑志,王如宾,等.不同应力路径下花岗片麻岩渗透特性的试验研究[J].岩石力学与工程学报,2016,35(2):260-267.(WANG Wei,ZHENG Zhi,WANG Rubin,et al.Experimental study of permeability properties of granitc gneiss under different stress paths[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):260-267.(in Chinese))
[12]WU G,ZHANG L.Studying unloading failure characteristics of a rock mass using the disturbed state concept[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(3):437-437.
[13]ZHAO X G,WANG J,CAI M,et al.Influence of unloading rate on the strain burst characteristics of beishan granite under true-triaxial unloading conditions[J].Rock Mechanics and Rock Engineering,2014,47(2):467-483.
[14]李建林,王瑞红,蒋昱州,等.砂岩三轴卸荷力学特性试验研究[J].岩石力学与工程学报,2010,29(10):2 034-2 041.(LI Jianlin,WANG Ruihong,JIANG Yuzhou,et al.Experimental study of sandstone mechanical properties by unloading triaxial tests[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(10):2 034-2 041.(in Chinese))
[15]黄润秋,黄达.卸荷条件下岩石变形特征及本构模型研究[J].地球科学进展,2008,23(5):441-447.(HUANG Runqiu,HUANG Da.Study on deformation characteristics and constitutive model of rock on the condition of unloading[J].Advances in Earth Sciences,2008,23(5):441-447.(in Chinese))
[16]黄润秋,黄达.高地应力条件下卸荷速率对锦屏大理岩力学特性影响规律的试验研究[J].岩石力学与工程学报,2010,29(1):21-33.(HUANG Ronqiu,HUANG Da.Experimental research oil affection laws of unloading rate on mechanical properties of Jinping marble under high geostress[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(1):21-33.(in Chinese))
[17]邓华锋,王哲,李建林,等.卸荷速率和孔隙水压力对砂岩卸荷特性影响研究[J].岩土工程学报,2017,39(11):1 976-1 983.(DENG Huafeng,WANG Zhe,LI Jianlin,et al.Effect of unloading rate and pore water pressure on mechanical properties of sandstone[J].Chinese Journal of Geotechnical Engineering,2017,39(11):1 976-1 983.(in Chinese))
[18]邱士利,冯夏庭,张传庆,等.不同卸围压速率下深埋大理岩卸荷力学特性试验研究[J].岩石力学与工程学报,2010,29(9):1 807-1 817.(QIU Shili,FENG Xiating,ZHANG Chuanqing,et al.Different unloading confining pressure rate of deep buried marble unloading mechanical properties test and research[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(9):1 807-1 817.(in Chinese))
[19]韩铁林,师俊平,陈蕴生,等.轴、侧向同卸荷下砂岩力学特性影响的试验研究[J].力学学报,2016,48(3):936-943.(HAN Tielin,SHI Junping,CHEN Yunsheng,et al.Experimental study on mechanics characteristics of sandstone under axial unloading and radial unloading path[J].Chinese Journal of Theoretical and Applied Mechanics,2016,48(3):936-943.(in Chinese))
[20]刘新荣,刘俊,冯昊,等.不同初始卸荷水平和水压下砂岩卸荷力学特性试验研究[J].岩土工程学报,2018,40(6):1 143-1 151.(LIU Xinrong,LIU Jun,FENG Hao,et al.Experimental research on unloading mechanical properties of sandstone under different initial unloading levels and pore pressures[J].Chinese Journal of Geotechnical Engineering,2018,40(6):1 143-1 151.(in Chinese))
[21]梁宁慧,刘新荣,包太,等.岩体卸荷渗流特性的试验[J].重庆大学学报:自然科学版,2005,28(10):133-135.(LIANG Ninghui,LIU Xinrong,BAO Tai,et al.Experimental study on the characteristic of seepage with unloading rock mass[J].Journal of Chongqing University:Natural Science,2005,28(10):133-135.(in Chinese))
[22]DAVY C A,SKOCZYLAS F,BARNICHON J D,et al.Permeability of macro-cracked argillite under confinement:gas and water testing[J].Physics and Chemistry of the Earth:Parts A/B/C,2007,32(8/14):667-680.
[23]何满潮,谢和平,彭苏萍,等.深部开采岩体力学研究[J].岩石力学与工程学报,2005,24(16):2 803-2 813.(HE Manchao,XIEHeping,PENG Suping,et a1.Study on rock mechanics in deep mining engineering[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(16):2 803-2 813.(in Chinese))
[24]黄润秋,黄达.卸荷条件下花岗岩力学特性试验研究[J].岩石力学与工程学报,2008,27(11):2 205-2 213.(HUANG Runqiu,HUANG Da.Experimental study on mechanical properties of granite under loading conditions[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2 205-2 213.(in Chinese))