Study on the construction technology of short-distance shield tunnel under-crossing existing tunnel

Under the condition of short-distance shield tunnel under-crossing existing tunnel without reinforcing existing internal tunnel and surroundings,using FLAC3D finite difference program,the paper simulates and calculates the subsidence deformation of surface and existing tunnel and the maximum stress between the two layers,optimizes the shield construction parameters according to numerical calculation.When the shield tunnel construction is within the influential domain of the existing tunnel,the automatic monitoring is set out for existing tunnel.According to the monitoring results,it further adjusts shield parameters,so as to make the shield tunnel fast crossing existing tunnel.As a result,it achieves great social and economic benefits.