复杂岩溶地层大口径DRCP顶管施工试验研究OA北大核心CSTPCD

The maximum jacking force during the construction of large-diameter reinforced concrete pipe(DRCP)in complex karst strata is the most critical construction control index,which determines the efficiency of pipe jacking construction.In order to study the variation rule of the jacking force,a force balance model of DRCP jacking process was established.Based on the pipeline project of Guiyang"Wangjia Dajing"water source emergency project,an in-situ test of the jacking process of DRCP in karst for-mation was carried out.The DRCP jacking force was monitored and analyzed in real-time.The results showed that the jacking process of DRCP was mainly divided into cutting force equilibrium stage,gradual change of jacking force equilibrium stage and re-sistance equilibrium stage.For the flint limestone,grey rock and sandy shale in karst area,the average resistance fk of DRCP with thixotropic slurry as drag reduction was 6.06,5.81,3.78 kN/m2 respectively,which can be a reference value for similar pipe jacking projects by being multiplied by the safety factor.Thixotropic mud as drag reducing DRCP has different jacking resistance in different rock mass jacking process.The harder the rock,the higher the average cutting force,average friction force and compre-hensive friction coefficient of DRCP.The proposed method of calculating the jacking force of large-diameter DRCP in complex karst strata is of great significance for clarifying the control indexes of DRCP jacking construction,and guaranteeing the construc-tion safety and progress.