已有围岩纵剖面LDP曲线对比及影响因素分析

Comparison of Existing Longitudinal Displacement Profile of Surrounding Rock Mass and Analysis of Influencing Factors

收敛-约束法是隧道结构设计的实用方法之一,围岩纵剖面曲线(LDP)是该方法成功运用的关键.在收集整理现有LDP曲线公式基础上,对其优缺点进行了对比分析,同时利用数值软件研究了岩体强度及变形特性对LDP曲线的影响.结果表明:由于研究出发点不同,对于同一工程基于已有LDP曲线公式采用相应数据输入后所得到曲线形态相差较大;粘聚力、摩擦角对曲线形态影响较大,弹性模量、剪胀角对于LDP曲线基本无影响;泊松比对弹性介质LDP形态基本无影响,但洞壁围岩塑形屈服区范围越大,泊松比影响越大.在实际工程中为获得LDP曲线,建议采用数值计算的方法并考虑粘聚力、摩擦角以及泊松比的离散影响.研究结果可为地下隧洞(道)采用收敛-约束法初期支护参数设计中LDP曲线的获得提供借鉴与参考.

The convergence-confinement method is one of the practical methods for designing the tunnel struc-ture systems.The curve of longitudinal displacement profile for surrounding rock(LDP)is the key to the successful application of this method.On the basis of collecting and arranging the existing LDP curves,the advantages and disadvantages of the LDP curves are compared and analyzed.At the same time,the numerical simulation software is used to deeply analyze the influence of rock mass strength and deformation properties on the curve of surrounding rock profiles.The results show that for the same project,based on the existing LDP curve formula,the curves obtained by the corresponding data differ greatly.The cohesion and friction angle greatly influence the curve shape of the longitudinal displacement profile of the surrounding rock,while the elastic modulus and dilatancy angle have no effect on the LDP curve shape.Poisson′ss ratio has no effect on the LDP shape of the elastic medium.However,the larger plastic deformation zone results in greater effect of the Poisson’s ratio.In order to obtain the LDP curve in practical engineering,it is suggested to adopt the numerical method and consider the discrete influence of cohesion,friction angle and Poisson’s ratio.The research results can provide for obtaining the LDP curve in the initial support parameters design of the underground tunnel by using the convergence-confinement method.