Study On The Stability Of Existing Tunnel Caused By Adjacent Undercrossing Construction

Development and utilization of underground space leads to a large number of nearly projects.In this paper,it is based on a under-crossing engineering of two tunnels in Dandong.Analysis of influencing scope and extent of the existing tunnel when the new tunnel under crossing from both the displacement and stress changes of the tunnel and the changes of plastic zone in the middle layer and other factors by the method of Numerical simulation and field measurement.At the same time,analysis of the influential effect of existing tunnel on clear distance factors,Put forward the corresponding engineering measures combining with the characteristics of both the deformation and stress distribution of existing tunnel and calculate its effectiveness.The main research results are as follows:(1)Analysis of displacement and stress change rule of existing tunnel with the influence of new tunnel under-crossing.To determine the settlement and stress of the tunnel control standards combined with the relative curve deformation and the stress increment.and then deciding the impact scope and degree of existing tunnel under by the influence of new tunnel under-crossing.(2)The study found that the process of under crossing.For the settlement,Existing tunnel affected mainly of the vertical displacement change and presents the obvious trend of settling tank;there are many differences between horizontal and vertical settlement with the development of the construction process,At the same time,lateral deformation exists strong directivity(3)The existing tunnel middle cross section affected larger when the process of under crossing by th e method of numerical simulation and field measurement Transverse performance for tensile stress increment and longitudinal performance for compressive stress increment.and obtained stress increment change rule According to the control criteria to determine both the tunnel affected by the weak(4)Analyzed the different interval(0.25 D,0.5 D and 0.75 D,1.0 D and 1.5 D)affected by the impact scope and degree of the existing tunnel.obtain the calculation formula of Clear distance with existing tunnel stress increment,And then to predict both the reasonable clear distance tunnel affected by different degree.At the same time,based on existing tunnel damage location easily put forward four kinds of reinforcement scheme and then analysis of the effects of each scheme...