公路隧道施工扰动分析方法探讨

Discussion on Method for Analysing Construction Disturbance in Highway Tunnel

为了量化研究施工扰动对隧道工程稳定性的影响,采用了理论分析、数值计算的方法,分析了与施工扰动影响密切相关的各类因素,构建了最小施工扰动分析方法及其与隧道工程稳定性的关系。利用拱顶下沉和周边收敛指标建立了反映施工扰动影响的隧道位移评判指标,并依据规范给出了拱顶下沉指标和周边收敛指标取值范围。提出了考虑围岩对原岩应力力学状态的继承能力和围岩安全状态的围岩自承载能力评判方法与表达式,给出了围岩自承载能力评判区域。修正了既有隧道衬砌安全系数,提出了反映施工扰动影响的隧道衬砌安全度评判指标。构建了由隧道位移评判指标、围岩自承载能力评判指标和衬砌安全度评判指标确定的隧道施工最小扰动综合评判公式,并给出了隧道施工扰动程度与隧道稳定状态对应关系及等级划分标准。采用提出的最小扰动分析方法对福州机场二期高速公路工程中金鸡山隧道的两种施工方法进行对比分析,结果表明:采用双侧壁导坑法和CRD法施工,隧道稳定性均属于良好级别,双侧壁导坑法对隧道扰动程度小于CRD法,隧道施工采用双侧壁导坑比CRD法更有利于隧道稳定性。

In order to quantitatively study the influence of construction disturbance on the stability of tunnel engineering,by using theoretical analysis and numerical calculation,the factors that are closely related to construction disturbance are analyzed,and the minimum construction disturbance analysis method and its relationship with the stability of tunnel engineering are constructed.The tunnel displacement evaluation indicator reflecting the influence of construction disturbance is established by using vault subsidence and surrounding convergence,and the value ranges of vault subsidence and surrounding convergence are given according to the specification.The evaluation method and the expression of surrounding rock self-bearing capacity considering the inheritance ability of surrounding rock to the original rock stress and the safety state of surrounding rock are proposed,and the evaluation area of the self-bearing capacity of surrounding rock is given.The safety factor of the existing tunnel lining is revised,and the evaluation indicator of the safety degree of the tunnel lining reflecting the influence of construction disturbance is put forward.The comprehensive evaluation formula of the minimum disturbance of tunnel construction,which is determined by the evaluation indicators of tunnel displacement,surrounding rock self-bearing capacity and lining safety degree,is established,and the corresponding relationship between the degree of tunnel construction disturbance and the tunnel stability state as well as the grading criterion are given.Finally,the 2 construction methods for Jinjishan Tunnel in Fuzhou airport second-phase expressway project are compared by the proposed minimum disturbance analysis method.The result indicates that the tunnel can be stable during the construction using both double-side drift method and CRD method,the disturbance degree of double-side drift method is less than that of CRD method,thus the use of double-sided drift method in tunnel construction is more conducive to the stability of the tunnel than the CRD method.