摘要 |
<p>First and second assemblies (18 and 30) respectively having each of a pair of plate-shaped retaining means (24 and 26) are alternately moved forwardly by a driving means (22). During this movement, ground (14) is dug to form a groove (16). A reaction force acting on the first assembly (24) during the forward movement of the second assembly (36) and a reaction force acting on the second assembly during the forward movement of the first assembly are respectively applied to the ground defining the groove through first and second position maintaining means (32 and 52). When the first and second assemblies are moved forwardly over a predetermined distance, a new pipe (12) is placed in the groove and connected to a pipe (12) which has been previously laid.</p> |