4Baumert M E,Allouche,E N.Methods for estimating pipe pullback loads for horizontal directional drilling(HDD)crossings[J].Journal of Infrastructure Systems,2002,8(1):12-19.
5Cheng E,Polak M A.Theoretical model for calculating pulling loads for pipes in horizontal directional drilling[J].Tunnelling and Underground Space Technology,2007,22:633-643.