| With the further promotion of urbanization in our country,there is an increasing number of cross intersections between tunnel engineering and ground buildings.The interaction between pile foundation and rock tunnel is very complex.At present,few theoretical research has been conducted on the whole model of pile foundation and rock tunnel.It is the current engineering problem to ensure the stability and safety of the structure,foundation and tunnel in the cross section of tunnel engineering and ground construction.Based on this,this paper studies the stability of tunnel surrounding rock and lining under the condition of the superstructure and foundation load.Through the finite element incremental load method as well as combined with the engineering example,the paper,based on rock strength criterion and overload safety factor,analyzes the variation of tunnel surrounding rock and lining stability effect of cross section of pile under load.In the process of research,the following results are obtained:(1)By modeling the comparatively analyzing the results of finite element calculation and engineering test data,the results show that both data are consistent,which authenticates the rationality of the finite element model;The maximum deformation of surrounding rock were less than the deformation control standards which applied to this project,indicating that the K4+869 and K4+889 sections can meet the stability requirements,which is consistent with the actual situation.(2)This paper,applying the finite element incremental load method to study the stability problem of surrounding rock in pile foundation rock tunnel model,quantitatively determines the critical line in pile and tunnel interaction model through the comparative analysis of the limit load of pile foundation under the situation of different position between pile foundation and tunnel;Out of the critical line between pile foundation and tunnel,so that models and strata effect should be regarded as independent;Inside of the critical line,so that overall analysis model for pile foundation rock tunnel needs to be applied;Through the analysis of pile and the critical line,pile load impact the rock deformation,stress and plastic deformation,the rationality of pile the tunnel boundary is authenticated.By applying the finiteelement method to calculate the overload Safety factor method for quantitative evaluation of surrounding rock stability.(3)Through the safety coefficient to quantitatively evaluate the surrounding rock stability.The stability of surrounding rock increases gradually with tunnel vertical pile spacing and the rock grade increased or enhanced,and it is the most sensitive when the pile is located above the tunnel wall;With the increase of horizontal distance between tunnel and pile,the stability of surrounding rock decreases first and then increases.And also determines the most unfavorable pile position which is S=3m,H=5m in the intersection zone.Study indicates that the pile load corresponding to the safety factor of the surrounding rock equals to 2,and realizes the control of the stability of the surrounding rock in the whole model of the pile rock tunnel.(4)Based on the calculation of lining safety coefficient formula which is specified in the "JTG D70-2004 highway tunnel design specification".The formula for the safety coefficient with the outcome being the stress of the lining is calculated,and the basis of judgment in different control type of lining safety coefficient is derived.Through the analysis of different lining safety coefficient of pile by load,different pile spacing and different levels of vertical distance between pile and tunnel,the influence laws of the stability of lining on the safety coefficient of control values corresponding to each pile of different pile load increasing value for the critical load are understood.After guaranteeing the stability of the surrounding rock control with load,indicating that the smaller value should be chosen for the design. |
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