基于应力解除法的九岭山隧道洞壁二次应力场分布规律研究
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摘要
为了解九岭山隧道开挖后洞壁二次应力场分布规律及其与岩爆发生状况之间的关联性,采用应力解除法沿九岭山隧道全线选取岩体完整,受开挖扰动小的部位进行了洞壁二次应力的实测,并结合现场岩爆实际发生情况,对洞壁二次应力场的分布规律进行综合对比分析,并结合应力判据对岩爆进行了二次准确预测。研究结果表明:洞壁二次应力值与隧道埋深呈现近似线性关系,二次应力量值呈现σ_1>σ_θ>σ_x>σ_3>τ_(xy)的特征;洞壁切向应力σ_θ最大为63.944 MPa,最大主应力σ_1最大值为77.17 MPa,二者量值相差7.5%,对岩爆的发生均起主导作用;洞室开挖后的洞壁切向应力σ_θ与埋深的相关系数为0.933 23,相比最大主应力σ_1与埋深的相关系数0.897 22,σ_θ与埋深的相关性更好;隧道开挖后,切向应力σ_θ在30～50 MPa范围内时可初步判定将可能发生微岩爆,σ_θ大于50 MPa时可初步判定将可能发生中等岩爆;以此为基础,再结合应力判据可对岩爆发生等级做出准确预测。研究成果为高地应力硬岩隧道岩爆预测提供新的思路。
In order to understand the distribution law of the secondary stress field in the tunnel wall after the excavation of Jiuling Mountain Tunnel and its correlation with the occurrence of rock burst, the actual measurement of the secondary stress in the tunnel wall is carried out through adopting the stress relief method to select the integral rock mass and the positions with less disturbance from excavation along the whole line of the tunnel, and then a comprehensivecontrastive analysis is made on the distribution law of the secondary stress field in the tunnel wall in combination with actual occurrence of the in situ rock burst, while the secondary accurate prediction is made on the rockburst occurred therein with the relevant stress criterion. The study result shows that an approximate linear relationship is there between the value of the secondary stress in the tunnel wall and the buried depth of the tunnel, for which the magnitude of the secondary stress exhibits the characteristics of σ_1>σ_θ>σ_x>σ_3>τ_(xy).The maximum tangential stress σ_θ of the tunnel wall is 63.944 MPa and the maximum value of the maximum principal stressσ_1 is 77.17 MPa; for which a difference of 7.5% is between both of the magnitudes of them, thus both of them play the leading roles for the occurrence of rockburst. The coefficient of the correlation between the tangential stressσ_θof the tunnel wall after the excavation and the buried depth is 0.933 23, which is much better if coMPared with the correlative coefficient of 0.897 22 between the maximum principal stress σ_1 and the buried depth. After the excavation of the tunnel, when the tangential stress σ_θ is within the range of 30～50 MPa, it is can be preliminarily determined that a micro-rockburst is possibly to occur, while the possible occurrence of a moderate rockburst can be preliminarily determined when σ_θ is larger than 50 MPa. On the basis of this and in combination with the relevant stress criterion, an accurate prediction of the occurrence grade of rockburst can be made. The study result can provide a new idea for the study on the rockburst prediction for the excavation of hard rock tunnel under high geostress.
In order to understand the distribution law of the secondary stress field in the tunnel wall after the excavation of Jiuling Mountain Tunnel and its correlation with the occurrence of rock burst, the actual measurement of the secondary stress in the tunnel wall is carried out through adopting the stress relief method to select the integral rock mass and the positions with less disturbance from excavation along the whole line of the tunnel, and then a comprehensivecontrastive analysis is made on the distribution law of the secondary stress field in the tunnel wall in combination with actual occurrence of the in situ rock burst, while the secondary accurate prediction is made on the rockburst occurred therein with the relevant stress criterion. The study result shows that an approximate linear relationship is there between the value of the secondary stress in the tunnel wall and the buried depth of the tunnel, for which the magnitude of the secondary stress exhibits the characteristics of σ_1>σ_θ>σ_x>σ_3>τ_(xy).The maximum tangential stress σ_θ of the tunnel wall is 63.944 MPa and the maximum value of the maximum principal stressσ_1 is 77.17 MPa; for which a difference of 7.5% is between both of the magnitudes of them, thus both of them play the leading roles for the occurrence of rockburst. The coefficient of the correlation between the tangential stressσ_θof the tunnel wall after the excavation and the buried depth is 0.933 23, which is much better if coMPared with the correlative coefficient of 0.897 22 between the maximum principal stress σ_1 and the buried depth. After the excavation of the tunnel, when the tangential stress σ_θ is within the range of 30～50 MPa, it is can be preliminarily determined that a micro-rockburst is possibly to occur, while the possible occurrence of a moderate rockburst can be preliminarily determined when σ_θ is larger than 50 MPa. On the basis of this and in combination with the relevant stress criterion, an accurate prediction of the occurrence grade of rockburst can be made. The study result can provide a new idea for the study on the rockburst prediction for the excavation of hard rock tunnel under high geostress.
引文
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[12] 汪波,何川,吴德兴.深埋特长隧道岩爆预测研究[J].铁道工程学报,2009,26(11):45- 49,68.
[13] LUO Y, CHEN J, HUANG P, et al. Deformation and mechanical model of temporary support sidewall in tunnel cutting partial section[J]. Tunnelling and Underground Space Technology, 2017, 61: 40- 49.
[14] 刘允芳,尹健民,刘元坤.深钻孔套芯应力解除法的测量技术和实例[J].长江科学院院报,2008,25(5):1- 6.
[15] 徐芝纶.弹性力学[M].北京:清华大学出版社,2013.
[16] 中铁二院工程集团有限责任公司.铁路隧道设计规范:TB 10003—2016[S]. 北京:中国铁道出版社,2017.
[17] 关宝树. 隧道工程施工要点集(第2版)[M].北京:人民交通出版社, 2011.
[18] 徐林生, 王兰生, 李永林. 岩爆形成机制与判据研究[J]. 岩土力学, 2002, 23(3): 300- 303.
[2] FAN Y, LU W, ZHOU Y, et al. Influence of tunneling methods on the strainburst characteristics during the excavation of deep rock masses[J]. Engineering Geology, 2016, 201: 85- 95.
[3] 张镜剑,傅冰骏.岩爆及其判据和防治[J].岩石力学与工程学报,2008,27(10):2034- 2042.
[4] 姚成林. 深埋长隧洞岩爆灾害机理及判据研究[D].北京:中国地质大学(北京),2014.
[5] 刘元坤,李永松,许静.基于切向应力指数及能量原理的岩爆机理分析[J].人民长江,2016,47(S2):105- 108.
[6] 郭建强,刘新荣.强度准则与岩爆判据统一的研究[J].岩石力学与工程学报,2018,37(S1):3340- 3352.
[7] TONON F, AMADEI B. Stresses in anisotropic rock masses: an engineering perspective building on geological knowledge[J]. International Journal of Rock Mechanics and Mining Sciences, 2003, 40(7/8): 1099- 1120.
[8] KUSUI A, VILLAESCUSA E, FUNATSU T. Mechanical behaviour of scaled-down unsupported tunnel walls in hard rock under high stress[J]. Tunnelling and Underground Space Technology, 2016, 60: 30- 40.
[9] 张蕊,王自高,王昆,等.复杂地质条件下地下洞室群围岩稳定性研究[J].人民黄河,2016,38(5):92- 94,99.
[10] 陈祥,孙进忠,张杰坤,等.岩爆的判别指标和分级标准及可拓综合判别方法[J].土木工程学报,2009,42(9):82- 88.
[11] 马亢,徐进,王兰生,等.雪峰山公路隧道岩爆问题的分析预测研究[J].公路,2008(1):204- 208.
[12] 汪波,何川,吴德兴.深埋特长隧道岩爆预测研究[J].铁道工程学报,2009,26(11):45- 49,68.
[13] LUO Y, CHEN J, HUANG P, et al. Deformation and mechanical model of temporary support sidewall in tunnel cutting partial section[J]. Tunnelling and Underground Space Technology, 2017, 61: 40- 49.
[14] 刘允芳,尹健民,刘元坤.深钻孔套芯应力解除法的测量技术和实例[J].长江科学院院报,2008,25(5):1- 6.
[15] 徐芝纶.弹性力学[M].北京:清华大学出版社,2013.
[16] 中铁二院工程集团有限责任公司.铁路隧道设计规范:TB 10003—2016[S]. 北京:中国铁道出版社,2017.
[17] 关宝树. 隧道工程施工要点集(第2版)[M].北京:人民交通出版社, 2011.
[18] 徐林生, 王兰生, 李永林. 岩爆形成机制与判据研究[J]. 岩土力学, 2002, 23(3): 300- 303.