Mechanical Analysis of Trenchless Directional Drill String in Horizontal Section and Slant Section

摘要

Trajectory of trenchless directional drill strings included slant section,bending section and horizontal section.Trenchless directional drill strings were under axial compression force during drilling process,while under axial tension force during hole reaming process and pulling back process.Because the trajectory and strength of trenchless directional drill string were influenced by the force exerted on each section,mechanical models of directional drill string were established to analyze the deflection equations and reaction forces in slant section and horizontal section under axial tension force and axial compression force.The boundary conditions in each section were taken as fixed constraint at one end and active constraint at the other end.After the analysis,the expressions of reaction forces as well as the deflection equations were deduced.And also,the reaction forces in horizontal section were got with given parameters of trenchless directional drill string based on the expression of reaction forces.