Method of laying drainage tubing

Claim 1

A method of laying generally horizontal wellpoint/drainage tubing for use in the dewatering of ground, comprising progressively excavating a slot-like trench having a width which is small in comparison with the depth of said trench by advancing a digging mechanism along a predetermined route to mechanically dig out spoil, said digging mechanism including a substantially vertically oriented endless chain having a series of cutters thereon, said endless chain and its cutters being driven along a closed path while said digging mechanism is advanced along said predetermined route thereby to bring said spoil to the top of said trench, said closed path having a length aloNg said trench which is substantially smaller than the depth of said trench, supporting the sides of said trench as said excavating step proceeds by positioning a pair of vertically oriented horizontally spaced plates adjacent the sides of said trench and by advancing said plates along said trench together with said digging mechanism, directing the spoil brought to the top of said trench in a lateral direction away from and to one side of the trench being dug to prevent at least the majority of the spoil removed from the trench from being returned to the trench, laying a continuous length of flexible, perforated tubing along the bottom of the trench by advancing a coil of said tubing along said predetermined route together with said digging mechanism and supporting plates and by progressively feeding said continuous length off said coil and through a substantially vertically oriented guide structure which is located between said supporting plates at a position rearward of said digging mechanism, said guide structure extending into said trench to a position adjacent to but spaced from the bottom of said trench and said guide structure being advanced along said trench together with said supporting plates to direct said tubing in a substantially vertical direction toward the bottom of said trench whereafter, at a location between said supporting plates and adjacent the bottom of said trench, the tubing bends to lie along the bottom of said trench, thereafter immediately and substantially completely backfilling the region of the trench between said supporting plates with a water-pervious material different from the spoil, said backfilling step being effected concurrent with the laying of said tubing by advancing a hopper containing said water-pervious material along said predetermined route together with said digging mechanism, supporting plates, coil of tubing, and guide structure and by discharging said water-pervious material from said hopper, into said trench and over and around the length of tubing emerging from said guide structure, through a discharge chute which extends from the hopper into the trench at a location between said supporting plates and rearward of said guide structure, and connecting the flexible tubing to suction pumping means, said digging mechanism, supporting plates, coil of tubing, guide structure, hopper, and discharge chute all being mounted in fixed position relative to one another on a common structure which is advanced as a unit along said predetermined route.

Claim 2

A method of laying generally horizontal wellpoint/drainage tubing for use in the dewatering of ground, comprising progressively excavating a slot-like trench having a width which is small in comparison with the depth of said trench by advancing a digging mechanism along a predetermined route to mechanically dig out spoil, said digging mechanism including a substantially vertically oriented endless chain having a series of cutters thereon, said endless chain and its cutters being driven along a closed path while said digging mechanism is advanced along said predetermined route thereby to bring said spoil to the top of said trench, said closed path having a length aloNg said trench which is substantially smaller than the depth of said trench, supporting the sides of said trench as said excavating step proceeds by positioning a pair of vertically oriented horizontally spaced plates adjacent the sides of said trench and by advancing said plates along said trench together with said digging mechanism, directing the spoil brought to the top of said trench in a lateral direction away from and to one side of the trench being dug to prevent at least the majority of the spoil removed from the trench from being returned to the trench, laying a continuous length of flexible, perforated tubing along the bottom of the trench by advancing a coil of said tubing along said predetermined route together with said digging mechanism and supporting plates and by progressively feeding said continuous length off said coil and through a substantially vertically oriented guide structure which is located between said supporting plates at a position rearward of said digging mechanism, said guide structure extending into said trench to a position adjacent to but spaced from the bottom of said trench and said guide structure being advanced along said trench together with said supporting plates to direct said tubing in a substantially vertical direction toward the bottom of said trench whereafter, at a location between said supporting plates and adjacent the bottom of said trench, the tubing bends to lie along the bottom of said trench, thereafter immediately and substantially completely backfilling the region of the trench between said supporting plates with a water-pervious material different from the spoil, said backfilling step being effected concurrent with the laying of said tubing by advancing a hopper containing said water-pervious material along said predetermined route together with said digging mechanism, supporting plates, coil of tubing, and guide structure and by discharging said water-pervious material from said hopper, into said trench and over and around the length of tubing emerging from said guide structure, through a discharge chute which extends from the hopper into the trench at a location between said supporting plates and rearward of said guide structure, and connecting the flexible tubing to suction pumping means, said digging mechanism, supporting plates, coil of tubing, guide structure, hopper, and discharge chute all being mounted in fixed position relative to one another on a common structure which is advanced as a unit along said predetermined route.