Study On Reasonable Offset And Safety Control Measures For The Through-face Of Small Clear Distance Tunnel In Weak Surrounding Rocks

Due to the complicated geological conditions,the construction efficiency and the construction cost,the two-way tunneling of the weak and small-distance tunnels of the weak surrounding rock often occurs parallel to the left and right holes.In the process of construction,the deformation of the surrounding rock is large,and the interaction between each other is obvious.It is very easy to lead to the deformation of the first branch of the tunnel,the two lining cracking,and even the safety accidents such as falling block,collapse and so on.In this paper,ZhongHeCun Tunnel is regarded as the engineering background,Combined with the design of tunnel survey data,through the tunnel construction site using a variety of methods to carry out detailed investigation and accurate detection,through the section of surrounding rock geological conditions,geological disasters and related mechanical parameters are determined,through the numerical simulation analysis of the different schemes of the tunnel through fault surface,a reasonable penetration scheme is determined,the scheme is applied to practice.The deformation measurement of the surrounding rock and the stress and strain of the lining structure are analyzed and compared,and the reasonable range and the safety control mea-sures are obtained,thus ensuring the construction of the tunnel through the safety.The main research contents include the following:(1)The engineering mechanics characteristics of the weak surrounding rock are analyzed,factors related to the stability of the surrounding rock are summarized and summarized,comb-ined with the calculation method of surrounding rock pressure,the large deformation support and construction scheme of the small and small distance tunnel are discussed.(2)In view of the lack of design and survey data of ZhongHeCun Tunnel,Ground pene-trating radar short-range advanced geological prediction is used and combined with TRT reflection seismic tomography distance and high density electrical method long-distance geological exploration,The geologic condition of the surrounding rock of the tunnel is accura-tely predicted,and the corresponding mechanical parameters and theoretical basis are provid-ed for the numerical simulation of the tunnel through section.(3)In view of the actual situation of ZhongHeCun Tunnel,using MIDAS/GTS NX to establish a three-dimensional numerical model.The distribution characteristics of surrounding rock deformation,lining structure stress and strain are analyzed and compared in the two-way excavation of tunnel.The excavation of rock pillar through segment without reservation length and tunnel face excavation stagger optimized analysis.The results show that under the condition of the surrounding rock,the length of the cut section should be more than 10 meters,and the reasonable distance of the through hole is 3?5 times the diameter of the hole.(4)The unstable section of the tunnel in the village is explored and reinforced,the regression analysis of information data of the on-site monitoring and measurement,combined with the numerical analysis results,the safety countermeasures of the deformation control of the surrounding dike of the tunnel are studied,and Reasonable through the program and the emergency contingency plans are given.Both the observation and the measured results show that the penetrating effect is good,which provides the theoretical basis and scientific guidance for the small distance clearance of the weak surrounding rock.