An Improved Model to Calculate Pullback Force of Trenchless Horizontal Directional Drilling Pipeline

Table 2

Table of calculation results after improvement.

Computing method	Engineering
	AA	BB	CC
Unloading arch earth pressure method (kN)	1566	1218	695
Winch calculation method (kN)	857	1271	997
Actual pullback force (kN)	695	716	681