摘要
隧道掘进前方存在富水溶腔时,掌子面与富水溶腔之间的抗突水岩体(抗突体)厚度会随着隧道掘进逐渐减小,一旦达到极限厚度会引发突水灾害。准确预测抗突体最小安全厚度,可有效避免岩溶富水区隧道突水灾害发生。隧道掌子面前方岩溶水压作用可能导致抗突体发生剪切破坏和弯曲破坏,据此,本文建立了相对应的抗突体力学模型,并采用抗剪强度准则、抗弯强度准则、弹性薄板理论计算出抗突体最小安全厚度。本文方法计算结果与基于固支梁弯曲理论、岩柱剪切理论、突变理论得到的结果较为吻合。参数敏感性分析结果表明:1)隧道埋深较深时,抗突体易发生弯曲破坏;隧道埋深较浅时,抗突体易发生剪切破坏。2)抗突体最小安全厚度与隧道开挖半径、岩溶水压、围岩泊松比呈正相关,且影响程度从大到小顺序依次为隧道开挖半径、岩溶水压、围岩泊松比。3)模型边界条件会影响抗突体最小安全厚度,当隧道开挖半径R<6 m、岩溶水压P_(w)<0.35 MPa时,最小安全厚度可按边界简支情况计算;当隧道开挖半径R≥6 m、岩溶水压P_(w)≥0.35 MPa时,最小安全厚度须按边界固定情况计算。最后,结合一座发生突水的岩溶隧道案例,将对应参数代入弯曲Ⅰ型表达式计算出最小安全厚度,结果与工程中预留的厚度总体一致,表明本文最小安全厚度,结果解析解是合理的。
When a water-rich karst cavity exists in front of the tunnel face,the thickness of the anti-inrushing rock mass between the tunnel face and the water-rich karst cavity will gradually decrease as the excavation of the tunnel progresses.Once the thickness of the anti-inrushing rock mass reaches the limit,the water inrush disaster will occur.An accurate prediction of the minimum safe thickness of the anti-inrushing structure can effectively avoid the occurrence of water inrush disaster in karst area.For the shear failure and bending failure modes of the anti-inrushing structure caused by water pressure,the corresponding mechanical models of anti-inrushing structure are established.The minimum safe thicknesses of anti-inrushing structure for the two models are calculated by using the shear strength criteria,the bending strength criteria,and the elastic thin-plate theory.The results calculated by present models are in good agreement with those calculated on the basis of the bending theory of fixed beam,the shear theory of rock column,and catastrophe theory.The results of parameter sensitivity analysis show that:1)The water-insulat-ing rock mass of deep-buried tunnel is prone to the bending failure,and the water-insulating rock mass of shallow tunnel is prone to the shear fail-ure.2)The minimum safe thickness of anti-inrushing structure is positively correlated with tunnel excavation radius,karst water pressure and Poisson’s ratio,and the order of influence degree from large to small is tunnel excavation radius,karst water pressure and Poisson’s ratio of sur-rounding rock.3)The boundary conditions of the model will affect the minimum safe thickness of the anti-inrushing structure.When the excava-tion radius R<6 m and the karst water pressure P_(w)<0.35 MPa,the minimum safe thickness can be calculated based on the boundary simply sup-ported condition.When R≥6 m and P_(w)≥0.35 MPa,the minimum safe thickness need to be calculated based on the fixed boundary conditions.This method provides a new way for the calculation of water gushing of circular tunnel in water-rich karst area.Finally,combined with a karst tunnel with water inrush,the corresponding parameters are substituted into the bending typeⅠexpression,and the minimum safe thickness is generally consistent with the thickness reserved in the project,which shows that the analytical solution of the minimum safe thickness in this paper is reas-onable.
作者
肖前丰
李文龙
符文熹
文丽娜
袁星宇
叶飞
XIAO Qianfeng;LI Wenlong;FU Wenxi;WEN Lina;YUAN Xingyu;YE Fei(State Key Lab.of Hydraulics and Mountain River Eng.,Sichuan Univ.,Chengdu 610065,China;College of Water Resources&Hydropower,Sichuan Univ.,Chengdu 610065,China;Zhaotong Expressway Investment and Development Co.,Ltd.,Zhaotong 657000,China;Sichuan Highway Planning,Survey,Design and Research Inst.Ltd.,Chengdu 610041,China)
出处
《工程科学与技术》
EI
CSCD
北大核心
2022年第3期159-168,共10页
Advanced Engineering Sciences
基金
国家自然科学基金项目(42107172)
四川省科技厅基础研究重点项目(2020YFN0012,2020YFS0361)
四川大学基础研究项目(2021SCU12035)。
关键词
圆形隧道
抗突体
最小安全厚度
薄板理论
突水
circular tunnel
anti-inrushing structure
minimum safe thickness
theory of thin plates
water inrush
