基于Duncan–Fama收敛曲线的隧道结构安全系数计算  

Calculation of safety factor of tunnel structure based on Duncan-Fama convergence curve

作　　者：刘少峰[1] 苏永华[1] 李帅[1] 

机构地区：[1]湖南大学土木工程学院,湖南长沙410082

出　　处：《岩土工程学报》2016年第7期1307-1315,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51378195;51578232)

摘　　要：首先基于Duncan–Fama收敛函数及锚杆、喷射混凝土与金属网等支护单元特征函数,建立圆形巷道围岩收敛–约束关系曲线,同时建议非圆形断面巷道转化为圆形断面的适用方法,并剖析收敛–约束曲线所涵盖的围岩与支护体系间的动态发展关系。然后引入隧道洞壁径向位移沿隧道径向的开挖间隔的变化规律曲线,与收敛–约束曲线相结合从而共同形成岩体的开挖、支护与信息反馈的动态发展关联过程。最后,建议了隧道围岩稳定安全系数计算表达式,探讨了相关支护时机确定方法,并分析隧道开挖后其支护起始位置对围岩约束力的影响。基于上述成果,探讨了现有的根据岩体分级类比的地下结构支护设计方法不能定量评价其安全程度的缺陷。通过两个工程实例,详细说明所构建方法的操作和运行过程,并初步验证了其有效性。Firstly, convergence-confinement curve of circular tunnel surrounding rock isestablished based ontheDuncan-Fama convergence functionand characteristic functions for rock bolt, shotcrete and metal net.Meanwhile, how to convert noncircular section into circular section of a tunnel is solved, and the dynamic development relationship betweenthesurrounding rock and thesupporting system based on the convergence-confinement curve is also analyzed. Then, the longitudinal deformation profile （LDP）is introducedand the development process of excavation,supportandinformation feedbackabout rock mass is formedin conjunction with the convergence-confinement curve. Finally, the expressions forstablesafety factorof tunnel surrounding rock are proposed,andthe method for determining the relevant supporting time is discussed. The effect ofthe initial locationof the supporting systemon constraining forceofrock mass after tunnel excavation is analyzed. Using the abovementioned achievements, the existing shortage thatthe design methodfor supportof underground structure based on classification system ofrock mass can not quantitatively evaluate the degree of safety is investigated.Two practical cases show the implementation of the proposed method, and its availability is also verified.

关 键 词：Mohr–Coulomb准则 收敛曲线 支护结构特征曲线 收敛–约束原理 稳定性系数 

分 类 号：U451[建筑科学—桥梁与隧道工程]