Study On Construction Mechanical Properties Of Shallow Buried Large-span Tunnels

In the context of China's economic level and comprehensive development of highway construction,in order to improve the urban traffic congestion and insufficient road capacity,the proportion of tunnel projects in highway construction in our country is getting higher and higher,and the large span Tunnels are getting more and more.In this paper,a separate two-way four-lane shallow-buried large-span tunnel is taken as the object of study.Through the field monitoring method and FEA and other research methods,the shallow-buried large-span tunnel is excavated by double-The mechanical properties of the rock mass,the initial support,the temporary support and the anchor and other construction mechanics characteristics of the study,and the initial support structure of the supporting parts of the relevant parameters of the study,the preliminary conclusions of the following conclusions :(1)The measured data of the tunnel site monitoring are measured,the gray prediction model of the fractional order operator is introduced,and the actual data of the displacement of the surrounding rock are analyzed by MATLAB.(2)According to the actual project to establish shallow buried large-span tunnel through the use of double-wall method of mining analysis model,found in the analysis under the bias of the surrounding rock,the depth of the deep side of the arch at the horizontal side of the horizontal Displacement of the deformation trend is more obvious,the vertical direction of the arch will have upward uplift trend.(3)From the point of view of the stress change of the weak surrounding rock,after the tunnel support structure is completely closed,the stress concentration in the arch dome will be concentrated,and the stress concentration zone at the arch waist decreases with the closure of the supporting structure,Stress at the bottom of the arch is also more obvious.(4)From the point of view of the mechanical response of the bolt and the supporting structure,the anchor is mainly in the tensioned state,and the displacement of the temporary support in the extraction model is analyzed.From the trend chart,The law has a good control effect on the deformation of the surrounding rock.(5)Through the control variables,the establishment of a number of test programs,analysis of different types of shotcrete and different types of steel,summed up in a certain range to increase the thickness of concrete spray to improve the stiffness of the support structure can effectively control the deformation of the surrounding rock,Different sections of steel,that is,within a certain range to change the section size of steel to improve the cross-section stiffness to resist the deformation of the surrounding rock is not obvious.