Large-diameter Electric Pipe Jacking Tunnel Underneath Research On The Influence Of Existing High-speed Rail Pile Foundation

Pipe jacking construction technology is a widely used domestically-excavated tunneling technology,which has the characteristics of significant construction reliability and excellent economic benefits in application,especially in urbandense facility areas,under important buildings and surrounding environmental impact requirements Under the construction conditions,it has unparalleled advantages.With thecontinuousexpansion of the distance and depth of pipe jacking,theresearch onthe safety control technology of pipe jacking in underground tunnelengineeringhas become a hot topic in the field of construction.The thesis relies on the pipe jacking of the curved section and the under-penetrating section of a 2×660MW power generating unit extension project in Zhengzhou,and systematically carries out the construction of large-diameter and long-distance curved earth pressure balance jacking under complex geological environments and the operation of the jacking under the high-speed railway bridge pier Safetycontrol research.The main contents are analyzed as follows:1.Aiming at the project of underpassing high-speed railway pile foundationunder the pipe jacking tunnel,combining with the geological conditions of Zhengzhou and the actual site engineering,the grouting pressure during construction,the soil bunker pressure,the ratio of thixotropic mud,the calculation methodof jacking force,and the rectification measures for jacking construction After optimization analysis,the construction control method of power tunnel pipe jacking is given;2.According to the construction control results of the curve section,throughthe numerical simulation of the MIDAS GTS NX software,mainly studies the effects of the proposed power tunnel pipe jacking project on the vertical displacement,the longitudinal displacement and the transverse displacement of the pier of no.576 to no.579 xulankezhuan bridge.The change of displacement in different directions in different stages of pipe jacking machine crossing the pier is obtained.The simulation shows that the maximum deformation occurs on pier no.577 and no.578,which are close to the axis,with the settlement amount of 0.662 mm,and the displacement of 0.123 mm and 0.144 mm in the direction of the bridge,which are both less than the settlement warning value of 2mm;3.Through the statistical analysis of on-site measured data,it is found that the law of settlement deformation is consistent with the law of numerical simulation,butthe monitoring value is slightly larger than the simulation value,and the law of deformation along the bridge is consistent with the law of numerical simulation,but the result of monitoring deformation is greater than the simulation result,however,the displacement deformation law of the transverse bridge is not consistent with the simulation law,and the monitoring value is especially small,indicating that the pipe jacking crossing construction has a great influence on the settlement and the displacement of the bridge,while the displacement of the transverse bridge is not sensitive to the crossing construction.The research results can provide theoretical basis and reference for similar engineering construction control.