不同围压下卸荷速率对围岩变形与破坏的影响
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摘要
研究相关因素对巷道/隧道围岩变形及破裂形态特征的影响作用,可以为巷道/隧道的支护设计提供理论支撑。在课题组已成功构建的围岩试件开挖卸荷模型试验系统基础上,对水泥砂浆围岩试件进行不同初始围压下不同卸荷速率的系列试验。试验结果表明:(1)开挖卸荷对围岩变形及破坏的影响不仅存在于卸荷阶段,卸荷效应会在卸荷结束之后继续对巷道围岩产生影响,并且随着初始围压的增大,对卸荷后围岩变形的影响更为明显。(2)卸荷阶段的切向、轴向应变率均呈现先增大后逐渐减小的变化趋势。快速卸荷应变率峰值出现较早,慢速卸荷应变率峰值出现较晚。(3)初始围压相同时,卸荷速度增大,卸荷阶段应变率加快,变形总量越小。卸荷速度相同时,初始围压增大,卸荷阶段应变率加快,变形总量越大。(4)慢速卸荷破坏时,试件外壁完整,内壁上靠近底端出现片状剥落;快速卸荷破坏时,试件外壁上出现环状贯通裂隙伴随少量竖向微裂隙,内径缩减明显,内壁上出现岩块掉落现象。试验结果有利于进一步研究其他相关因素对围岩变形及破裂形态的影响机制。
Investigations of the influence of correlative factors on deformation and fracture characteristics of roadways/tunnels surrounding rocks can provide theoretical support for the supporting design of roadways/tunnels. A test system for excavation and unloading of surrounding rock specimens was developed,and a series of tests with different unloading rates under different initial confining pressures were carried out on the surrounding rock specimens made of cement mortar. The test results show that the influence of excavation unloading on the deformation and failure of surrounding rock exists not only in the unloading stage but also in the stage after unloading,and the influence in the stage after unloading is more obvious with increasing the initial confining pressure. Both the tangential and axial strain rates during the unloading stage increase firstly and then decrease. The peak of the rapid-speed unloading strain rate appears earlier than that of the slow-speed unloading strain rate. When the initial confining pressure is same,the higher the unloading speed is,the faster the deformation rate in the unloading stage is and at the same time,the smaller the total deformation is. When the unloading speed is same,the higher the initial confining pressure is,the faster the deformation rate in the unloading stage is and the larger the total deformation is. It is observed that,when the surrounding rock specimen is destroyed in the slow-speed unloading test,the outer wall of the specimen is intact but the inner wall near the bottom flakes,and that,in the rapid-speed unloading test,annular cracks occur along the outer wall of the specimen accompanied by a small amount of vertical micro-fractures,the inner diameter is reduced obviously and the rock on the inner wall falls. The research is helpful to further study the influence of relevant factors on surrounding rock deformation law and surrounding rock rupture form.
Investigations of the influence of correlative factors on deformation and fracture characteristics of roadways/tunnels surrounding rocks can provide theoretical support for the supporting design of roadways/tunnels. A test system for excavation and unloading of surrounding rock specimens was developed,and a series of tests with different unloading rates under different initial confining pressures were carried out on the surrounding rock specimens made of cement mortar. The test results show that the influence of excavation unloading on the deformation and failure of surrounding rock exists not only in the unloading stage but also in the stage after unloading,and the influence in the stage after unloading is more obvious with increasing the initial confining pressure. Both the tangential and axial strain rates during the unloading stage increase firstly and then decrease. The peak of the rapid-speed unloading strain rate appears earlier than that of the slow-speed unloading strain rate. When the initial confining pressure is same,the higher the unloading speed is,the faster the deformation rate in the unloading stage is and at the same time,the smaller the total deformation is. When the unloading speed is same,the higher the initial confining pressure is,the faster the deformation rate in the unloading stage is and the larger the total deformation is. It is observed that,when the surrounding rock specimen is destroyed in the slow-speed unloading test,the outer wall of the specimen is intact but the inner wall near the bottom flakes,and that,in the rapid-speed unloading test,annular cracks occur along the outer wall of the specimen accompanied by a small amount of vertical micro-fractures,the inner diameter is reduced obviously and the rock on the inner wall falls. The research is helpful to further study the influence of relevant factors on surrounding rock deformation law and surrounding rock rupture form.
引文
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[13]LABIOUSE V,SAUTHIER C,YOU S.Hollow cylinder simulation experiments of galleries in boom clay formation[J].Rock Mechanics and Rock Engineering,2014,47(1):53-55.
[14]侯公羽,李小瑞,张振铎,等.使用小型围岩试件模拟与再现巷道围岩开挖卸荷过程的试验系统[J].岩石力学与工程学报,2017,36(9):2 136-2 145.(HOU Gongyu,LI Xiaorui,ZHANGZhenduo,et al.Experimental system for simulating and reproducing excavation unloading process of roadway surrounding rock by using small-scale surrounding rock specimen[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(9):2 136-2 145.(in Chinese))
[15]DYSKIN A V,GERMANOVICH L N,USTINOV K B.A 3Dmodel of wing crack growth and interaction[J].Engineering Fracture Mechanics,1999,63(1):81-110.
[16]GERMANOVICH A V,SALGANIK R L,DYSKIN V,et al.Mechanisms of brittle fracture of rock with multiple pre-existing cracks in compression[J].Pure and Applied Geophysics,1994,143(1/3):117-149.
[17]李明田,李术才,张敦福,等.类岩石材料表面裂纹复合型断裂准则探讨[J].岩石力学与工程学报,2011,30(增1):3 326-3 333.(LI Mingtian,LI Shucai,ZHANG Dunfu,et al.Investigation on mixed-mode fracture criterion of surface crack in rock-line materials[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.1):3 326-3 333.(in Chinese))
[18]MARTIN C D.Seventeenth canadian geotechnical colloquium:The effect of cohesion loss and stress path on brittle rock strength[J].Canadian Geotechnical Journal,1997,34(5):698-725.
[19]侯公羽,牛晓松.基于Levy-Mises本构关系及Hoek-Brown屈服准则的轴对称圆巷理想弹塑性解[J].岩石力学与工程学报,2010,29(4):765-777.(HOU Gongyu,NIU Xiaosong.Perfect elastoplastic solution of axisymmetric cylindrical cavity based on Levy-Mises constitutive relation and Hoek-Brown failure criterion[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(4):765-777.(in Chinese))
[20]司雪峰,宫凤强,罗勇,等.深部三维圆形洞室岩爆过程的模拟试验[J].岩土力学,2018,39(2):621-633.(SI Xuefeng,GONGFengqiang,LUO Yong,et al.Experimental simulation on rockburst process of deep three-dimensional circular cavern[J].Rock and Soil Mechanics,2018,39(2):621-633.(in Chinese))
[21]卢文波,周创兵,陈明,等.开挖卸荷的瞬态特性研究[J].岩石力学与工程学报,2008,27(11):2 184-2 192.(LU Wenbo,ZHOU Chuangbing,CHEN Ming,et al.Research on Transient Characteristics of Excavation Unloading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2 184-2 192.(in Chinese))
[22]陈卫忠,吕森鹏,郭小红,等.脆性岩石卸围压试验与岩爆机理研究[J].岩土工程学报,2010,32(6):963-969.(CHEN Weizhong,LüSenpeng,GUO Xiaohong,et al.Unloading confining pressure for brittle rock and mechanism of rock burst[J].Chinese Journal of Geotechnical Engineering,2010,32(6):963-969.(in Chinese))
[2]张黎明,王在泉,孙辉,等.岩石卸荷破坏的变形特征及本构模型[J].煤炭学报,2009,34(12):1 626-1 631.(ZHANG Liming,WANG Zaiquan,SUN Hui,et al.Failure Characteristics and constitutive model of rock under unloading condition[J].Journal of China Coal Society,2009,34(12):1 626-1 631.(in Chinese))
[3]张晓君.高应力硬岩卸荷岩爆的劈裂判据及因素敏感性分析[J].采矿与安全工程学报,2013,30(1):80-85.(ZHANG Xiaojun.Splitting criterion of unloading rock burst for high-stress hard rock and its sensitivity analysis of factors[J].Journal of Mining and Safety Engineering,2013,30(1):80-85.(in Chinese))
[4]王蒙,朱哲明,冯若琪.真三轴加卸载条件下巷道周边裂隙岩体变形破坏试验研究[J].煤炭学报,2015,40(2):278-285.(WANG Meng,ZHU Zheming,FENG Ruoqi.Experimental study on failure behaviour of cracked rocks around tunnels under true triaxial unloading[J].Journal of China Coal Society,2015,40(2):278-285.(in Chinese))
[5]GAY N C.Fracture growth around openings in thick-walled cylinders of rock subjected to hydrostatic compression[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1973,10(3):209-233.
[6]ALSAYED M I.Utilising the Hoek triaxial cell for multiaxial testing of hollow rock cylinders[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,2002,39(3):355-366.
[7]苏承东,李冰洋,吴秋红.石灰岩孔道试样压缩条件下变形与强度特征的试验研究[J].岩石力学与工程学报,2016,35(增1):2 739-2 748.(SU Chengdong,LI Bingyang,WU Qiuhong.Experimental study on deformation and strength properties of hollow cylindrical specimens of limestone under compression[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(Supp.1):2 739-2 748.(in Chinese))
[8]李夕兵,吴秋红,董陇军,等.含充填物的厚壁圆筒砂岩的力学性质研究[J].岩土工程学报,2015,37(12):2 149-2 156.(LIXibing,WU Qiuhong,DONG Longjun,et al.Mechanical property of thick-walled hollow cylinders of sandstone with filling[J].Chinese Journal of Geotechnical Engineering,2015,37(12):2 149-2 156.(in Chinese))
[9]张后全,刘红岗,贺永年,等.岩石厚壁圆筒三向压缩下的卸荷试验与岩石强度破坏[J].北京科技大学学报,2011,33(7):800-805.(ZHANG Houquan,LIU Honggang,HE Yongnian,et al.Unloading experiment and rock strength failure of rock thick-walled cylinders under triaxial compression[J].Journal of University of Science and Technology Beijing,2011,33(7):800-805.(in Chinese))
[10]吴秋红,李夕兵,赵伏军,等.石灰岩孔道试样孔内卸压条件下破坏特征的研究[J].岩石力学与工程学报,2017,36(6):1 424-1 433.(WU Qiuhong,LI Xibing,ZHAO Fujun,et al.Failure characteristics of hollow cylindrical specimens of limestone under hole pressure unloading[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(6):1 424-1 433.(in Chinese))
[11]鲁建荣.基于厚壁筒三维解析模型的深部洞石围岩分区破裂化机制研究[J].岩土力学,2014,35(9):2 673-2 684.(LU Jianrong.Mechanism of zonal disintegration within surrounding rock of deep tunnel based on 3D analytical model of thick-walled cylinder[J].Rock and Soil Mechanics,2014,35(9):2 673-2 684.(in Chinese))
[12]LABIOUSE V,VIETOR T.Laboratory and in situ simulation tests of the excavation damaged zone around galleries in Opalinus clay[J].Rock Mechanics and Rock Engineering,2014,47(1):57-70.
[13]LABIOUSE V,SAUTHIER C,YOU S.Hollow cylinder simulation experiments of galleries in boom clay formation[J].Rock Mechanics and Rock Engineering,2014,47(1):53-55.
[14]侯公羽,李小瑞,张振铎,等.使用小型围岩试件模拟与再现巷道围岩开挖卸荷过程的试验系统[J].岩石力学与工程学报,2017,36(9):2 136-2 145.(HOU Gongyu,LI Xiaorui,ZHANGZhenduo,et al.Experimental system for simulating and reproducing excavation unloading process of roadway surrounding rock by using small-scale surrounding rock specimen[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(9):2 136-2 145.(in Chinese))
[15]DYSKIN A V,GERMANOVICH L N,USTINOV K B.A 3Dmodel of wing crack growth and interaction[J].Engineering Fracture Mechanics,1999,63(1):81-110.
[16]GERMANOVICH A V,SALGANIK R L,DYSKIN V,et al.Mechanisms of brittle fracture of rock with multiple pre-existing cracks in compression[J].Pure and Applied Geophysics,1994,143(1/3):117-149.
[17]李明田,李术才,张敦福,等.类岩石材料表面裂纹复合型断裂准则探讨[J].岩石力学与工程学报,2011,30(增1):3 326-3 333.(LI Mingtian,LI Shucai,ZHANG Dunfu,et al.Investigation on mixed-mode fracture criterion of surface crack in rock-line materials[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.1):3 326-3 333.(in Chinese))
[18]MARTIN C D.Seventeenth canadian geotechnical colloquium:The effect of cohesion loss and stress path on brittle rock strength[J].Canadian Geotechnical Journal,1997,34(5):698-725.
[19]侯公羽,牛晓松.基于Levy-Mises本构关系及Hoek-Brown屈服准则的轴对称圆巷理想弹塑性解[J].岩石力学与工程学报,2010,29(4):765-777.(HOU Gongyu,NIU Xiaosong.Perfect elastoplastic solution of axisymmetric cylindrical cavity based on Levy-Mises constitutive relation and Hoek-Brown failure criterion[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(4):765-777.(in Chinese))
[20]司雪峰,宫凤强,罗勇,等.深部三维圆形洞室岩爆过程的模拟试验[J].岩土力学,2018,39(2):621-633.(SI Xuefeng,GONGFengqiang,LUO Yong,et al.Experimental simulation on rockburst process of deep three-dimensional circular cavern[J].Rock and Soil Mechanics,2018,39(2):621-633.(in Chinese))
[21]卢文波,周创兵,陈明,等.开挖卸荷的瞬态特性研究[J].岩石力学与工程学报,2008,27(11):2 184-2 192.(LU Wenbo,ZHOU Chuangbing,CHEN Ming,et al.Research on Transient Characteristics of Excavation Unloading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2 184-2 192.(in Chinese))
[22]陈卫忠,吕森鹏,郭小红,等.脆性岩石卸围压试验与岩爆机理研究[J].岩土工程学报,2010,32(6):963-969.(CHEN Weizhong,LüSenpeng,GUO Xiaohong,et al.Unloading confining pressure for brittle rock and mechanism of rock burst[J].Chinese Journal of Geotechnical Engineering,2010,32(6):963-969.(in Chinese))