Apparatus and method for steering a pipe jacking head

Apparatus for laying pipe casings underground to form a cased bore which includes means for pushing a string of pipe casings joined together through the ground, and a forward pipe casing at a forward end of said string of pipe casings, said apparatus comprising:

• a steerable pipe jacking head carried by said forward pipe casing;
• a steering means carried by said pipe jacking head for creating a directional steering force for steering said head in a prescribed direction;
• said steering means having a desired rotational position in which said steering means creates said directional steering force to steer said pipe jacking head, and said steering means having an advanced position in which said steering means is extended forward of said pipe jacking head to create said directional steering force, and a retracted position in which said steering means is retracted into said pipe jacking head so that said directional force is not created;
• actuation means for moving said steering means between said advanced and retracted positions and for rotating said steering means to said desired rotational position to impart said directional steering force to steer said pipe jacking head and said pipe casings in said prescribed direction;
• and
• guidance means for measuring an inclination and heading of said pipe jacking head and generating first and second position signals corresponding to vertical and horizontal positions of said pipe jacking head.

A method for steering and guiding a steerable pipe jacking head which lays pipe casings underground, comprising:

• providing a steerable pipe jacking head having a steering means which is rotated within said pipe jacking head to a desired rotated position which corresponds to a desired steering direction, and then is extended from said pipe jacking head to steer said pipe jacking head, and then retracted so as not to steer said pipe jacking head;
• measuring the position of said pipe jacking head as it is pushed through the ground to lay pipe casings and generating position signals;
• and
• rotating and then extending said steering means in response to said position signals to steer said pipe jacking head as it is pushed through the ground in a prescribed direction along a desired path, and retracting said steering means after said pipe jacking head has been steered to said prescribed direction.