Zhongliangshan1st Tunnel Cross Over Eryan Railway’s Impact Analysis

With the development of transportation, the transportation routes become moreand more complex. The phenominon that the planning routes and the original routescross is commom. In the field of tunnel engineering, the condition that the tunnel underconstruction cross over or below the original tunnel exists. When the newly builttunnel cross the original tunnel in a short distance, diaturbance to soil will cause thedeformation of soil layer and additional stress of tunnel structure in excavation of thenewly built tunnel. when the deformation of tunnel structure exceeds the designedbearing limit, it will result in damage of the structure directly and affect the drivingsafety. At present, there are many newly built tunnel which cross below railway tunnel,but the newly built tunnel which cross over railway tunnel are rare. Many newproblems emerging can not be solved and there are no corresponding specification andstandard for design and construction. Therefore, only when we realize the affectingpatterns and affecting extent of the newly built tunnel which cross over the originaltunnel completely, the feasible construction scheme can be determined and theoperation safety can be ensured.On the basis of theoretical analysis, combining the engineering example that therail transit subway6th line Zhongliangshan1st tunnel cross over Eryan railway tunnel,by use of finite elenment numerical simulation and analysis of monitoring data in workfield, this article does research on the effect of the newlt built tunnel which cross overEryan railway tunnel. The main contents include:①By the theoretical analysis can know, geology, construction, structure, net isapart from the factors such as direct or indirect influence to some extent to the newlybuilt tunnel excavation of existing railway tunnel safety operation.②Through the actual field monitoring, the new existing railway tunnel verticaldisplacement caused by tunnel excavation show through settlement before, through theuplift, continue to uplift after crossing. The largest amount of subsidence and uplift inthe new tunnel and existing tunnel junction，Change trend roughly parabola. For boththe clearance of the tunnel convergence deformation situation reflects the railwaytunnel supporting structure mechanics form and the parameters of surrounding rock isthe most direct, through the net convergence monitoring can know the stability ofsurrounding rock and supporting structure. New tunnel excavation unloading due to the soil, the soil around the stress release of elastic-plastic deformation occurs, the overallrise, existing railway tunnel crossing after stable as a whole.③Through MIADAS-GTS numerical simulation can know, as a new tunnelexcavation, both the two rock railway tunnel vertical displacement increasescontinuously. The change tendency is parabola, basically the same change trend, underdifferent working condition of the variation is slightly different. By the numericalsimulation can be seen that a new tunnel to the influence of both two railway tunnelrock are mainly composed of vertical displacement.④Two different cross tunnel clear distance of both the influence degree of thetunnel are also different. Different interval both in the vertical displacement of thetunnel have the same change trend, the greater the net from the newly built tunnelexcavation influence on existing tunnel is smaller. When the interval is greater than the3D effect is very small.