卸荷速度对围岩变形影响的试验研究
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摘要
巷道/隧道围岩的开挖卸荷效应,直接关系到围岩稳定、支护设计和施工工艺的选择。利用自主研发的开挖卸荷试验系统,对水泥砂浆制作的厚壁圆筒小型围岩试件进行了快、慢速卸荷试验研究,获得小型围岩试件在开挖卸荷过程中的变形规律与破坏形态。试验结果表明:①快、慢速卸荷的径向应变及切向应变与时间的关系曲线表现出明显的3个特征阶段:试件压密阶段、快速变形阶段、卸荷后缓慢变形阶段。②同一横断面处,内侧的切向应变对卸荷作用反应更快、更显著,变形量更大。径向内侧产生的变形总量均大于外侧,而轴向内侧产生的变形总量小于外侧。③无论快速或慢速卸荷,同一测点处,切向应变最大,占据重要地位。径向变形集中在卸荷阶段产生,轴向变形集中在卸荷后维持阶段产生。④卸荷阶段,随着压差增大,慢速卸荷的切向、轴向应变呈加速发展趋势,内、外侧径向应变差值约为200×10~(-6)。快速卸荷的切向、轴向应变呈收敛发展趋势,内、外侧径向应变基本相同。维持阶段,快、慢速卸荷切向、轴向内外侧偏差持续增大。快速卸荷时内、外侧径向应变在维持阶段才开始区别开来,且差值越来越大。⑤试件压缩高度变低,且外侧出现环状贯通面并伴随劈裂破坏,在内壁出现片状剪切破坏区;横断面出现两个类似于圆环破坏带的破坏区。
The excavation unloading effect of roadway/tunnel surrounding rock is directly related to the stability of surrounding rock,the design of support and the selection of construction technology. Fast and slow unloading experiments were carried out to study the excavation unloading effect of small surrounding rock specimens made from cement mortar by using the independently developed experimental system of excavation and unloading. Deformation laws and failure patterns of the excavation unloading process were obtained. The test results show that : ① The relation curves of radial strain and tangential strain in fast and slow unloading and time show three characteristic stages : specimen compaction stage,rapid deformation stage,and slow deformation stage. ② In the same cross section,the tangential strain of the inner side reacts faster and more significantly to the unloading action,and greater deformation is produced. The total deformation produced by the inner side radial is greater than that on the outer side, while the total deformation produced by the inner side axis is less than that on the outer side. ③ No matter fast or slow unloading, the tangential strain at the same point is the most important and occupies an eminent position. The radial deformation is concentrated at unloading phase,and the axial deformation is concentrated in the maintenance phase after unloading. ④ In the unloading phase,with the increase in pressure difference, the tangential and axial strain of slow unloading show an accelerated development trend,and the radial strain difference value of inner and outer is about 200. The tangential and axial strains of quick unloading show a tendency of convergence, and the radial strains of inner and outer are basically the same. During the maintenance phase, the tangential and axial inner and outer deviations of the two unloading methods continue to increase. In the fast unloading phase,the radial strain on the inside and out lateral starts to differentiate and the difference becomes larger and larger. ⑤ The specimen is compressed and becomes shorter, and the annular penetrating surface appears on the outside and is accompanied by splitting failure, and the inner wall shows a slice-like shear failure zone. There are two damage zones in the cross section parallel to the ring damage zone.
The excavation unloading effect of roadway/tunnel surrounding rock is directly related to the stability of surrounding rock,the design of support and the selection of construction technology. Fast and slow unloading experiments were carried out to study the excavation unloading effect of small surrounding rock specimens made from cement mortar by using the independently developed experimental system of excavation and unloading. Deformation laws and failure patterns of the excavation unloading process were obtained. The test results show that : ① The relation curves of radial strain and tangential strain in fast and slow unloading and time show three characteristic stages : specimen compaction stage,rapid deformation stage,and slow deformation stage. ② In the same cross section,the tangential strain of the inner side reacts faster and more significantly to the unloading action,and greater deformation is produced. The total deformation produced by the inner side radial is greater than that on the outer side, while the total deformation produced by the inner side axis is less than that on the outer side. ③ No matter fast or slow unloading, the tangential strain at the same point is the most important and occupies an eminent position. The radial deformation is concentrated at unloading phase,and the axial deformation is concentrated in the maintenance phase after unloading. ④ In the unloading phase,with the increase in pressure difference, the tangential and axial strain of slow unloading show an accelerated development trend,and the radial strain difference value of inner and outer is about 200. The tangential and axial strains of quick unloading show a tendency of convergence, and the radial strains of inner and outer are basically the same. During the maintenance phase, the tangential and axial inner and outer deviations of the two unloading methods continue to increase. In the fast unloading phase,the radial strain on the inside and out lateral starts to differentiate and the difference becomes larger and larger. ⑤ The specimen is compressed and becomes shorter, and the annular penetrating surface appears on the outside and is accompanied by splitting failure, and the inner wall shows a slice-like shear failure zone. There are two damage zones in the cross section parallel to the ring damage zone.
引文
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[11]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):1626-1631.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):1626-1631.
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[13]李家卓,谢广祥,王磊,等.深部煤层底板岩层卸荷动态响应的变形破裂特征研究[J].采矿与安全工程学报,2017,34(5):876-883.LI Jiazhuo,XIE Guangxiang, WANG Lei,et al. Mechanical mechanism of dynamic fracture evolution of coal floor unloading in deep mining[J]. Journal of Mining and Safety Engineering,2017,34(5):876-883.
[14]蒋邦友,王连国,顾士坦,等.基于能量原理的深埋隧洞TBM施工岩爆机理分析[J].采矿与安全工程学报,2017,34(6):1103-1115.JIANG Bangyou,WANG Lianguo,GU Shitan,et al. Study on rockburst mechanism of TBM excavation for deep tunnel based on energy principle[J]. Journal of Mining and Safety Engineering,2017,34(6):1103-1115.
[15]丛宇,冯夏庭,郑颖人,等.脆性岩石宏细观破坏机制的卸荷速率影响效应研究[J].岩石力学与工程学报,2016,35(S2):3696-3705.CONG Yu,FENG Xiating,ZHNEG Yingren,et al. Study on effects of unloading rate on macro-meso failure mechanism of brittle rock[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(S2):3696-3705.
[16]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):2136-2145.HOU Gongyu, LI Xiaorui, ZHANG Zhenduo, 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):2136-2145.
[17]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.
[18] DYSKIN A V,GERMANOVICH L N,USTINOV K B. A 3D modelof wing crack growth and interaction[J]. Engineering Fracture Mechanics,1999,63(1):81-110.
[19] 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.
[20]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(S1):3326-3333.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(Sl):3326-3333.
[2]张永兴.岩石力学[M].北京:中国建筑工程出版社,2004.
[3]李涛.不同应力路径下粉砂岩力学特性及卸荷本构模型研究[D].徐州:中国矿业大学,2015.LI Tao. Siltstone's mechanical properties in different stress paths and research of unloading constitutive model[D]. Xuzhou:China University of Mining&Technology,2015
[4]李建林.卸荷岩体力学[M].北京:中国水利水电出版社,2003.
[5]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):2205-2213.HUANG Runqiu,HUANG Da. Experimental research on mechanical properties of granites under unloading condition[J]. Chinese Journal of Rock Mechanics and Engineering,2008,27(11):2205-2213.
[6]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):1807-1817.QIU Shili,FENG Xiating,ZHANG Chuanqing,et al. xperimental research on mechanical properties of deep-buried marble under different unloading rates of confining pressures[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(9):1807-1817.
[7]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):2034-2041.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):2034-2041.
[8]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):2673-2684.LU Jianrong. Mechanism of zonal disintegration within surrounding rock of deep tunnel based on 3D analytical model of thickwalled cylinder[J]. Rock and Soil Mechanics,2014,35(9):2673-2684.
[9] 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):1-7.
[10] NGUYEN T S, BORGESSON L, CHIJIMATSU M,et al. Hydromechanical response of a fractured granitic rock mass to excavation of a test pit-the Kamaishi Mine experiment in Japan[J]. International Journal of Rock Mechanics and Mining Sciences,2001,38(1):79-94.
[11]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):1626-1631.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):1626-1631.
[12]钱七虎,李树忱.深部岩体工程围岩分区破裂化现象研究综述[J].岩石力学与工程学报,2008,27(6):1278-1284.QIAN Qihu,LI Shuchen. A review of research on zonal disintegration phenomenon in deep rock mass engineering[J]. Chinese Journal of Rock Mechanics and Engineering, 2008,27(6):1278-1284.
[13]李家卓,谢广祥,王磊,等.深部煤层底板岩层卸荷动态响应的变形破裂特征研究[J].采矿与安全工程学报,2017,34(5):876-883.LI Jiazhuo,XIE Guangxiang, WANG Lei,et al. Mechanical mechanism of dynamic fracture evolution of coal floor unloading in deep mining[J]. Journal of Mining and Safety Engineering,2017,34(5):876-883.
[14]蒋邦友,王连国,顾士坦,等.基于能量原理的深埋隧洞TBM施工岩爆机理分析[J].采矿与安全工程学报,2017,34(6):1103-1115.JIANG Bangyou,WANG Lianguo,GU Shitan,et al. Study on rockburst mechanism of TBM excavation for deep tunnel based on energy principle[J]. Journal of Mining and Safety Engineering,2017,34(6):1103-1115.
[15]丛宇,冯夏庭,郑颖人,等.脆性岩石宏细观破坏机制的卸荷速率影响效应研究[J].岩石力学与工程学报,2016,35(S2):3696-3705.CONG Yu,FENG Xiating,ZHNEG Yingren,et al. Study on effects of unloading rate on macro-meso failure mechanism of brittle rock[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(S2):3696-3705.
[16]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):2136-2145.HOU Gongyu, LI Xiaorui, ZHANG Zhenduo, 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):2136-2145.
[17]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.
[18] DYSKIN A V,GERMANOVICH L N,USTINOV K B. A 3D modelof wing crack growth and interaction[J]. Engineering Fracture Mechanics,1999,63(1):81-110.
[19] 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.
[20]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(S1):3326-3333.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(Sl):3326-3333.