GB2102043A

GB2102043A - Process and apparatus for jacking conduits in ground containing ground water

Info

Publication number: GB2102043A
Application number: GB08121987A
Authority: GB
Inventors: Richard Weiss
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-07-16
Filing date: 1981-07-16
Publication date: 1983-01-26
Also published as: GB2102043B

Abstract

A conduit (not shown) is jacked into ground containing water from an excavation 1 using a sealed pressure- type cutter shoe 13. The excavation 1 is formed by driving in sheet piles 3 and excavating within the piles 3, allowing the ground water to flow in up to water table level 6. A concrete base 7 is then cast underwater and when set, the water is pumped out, a floor 8 and frame wall 10 having opening surrounded by an annular lip seal are then installed together with jacks 16 and cutter shoe 13. The cutter shoe 13 is sealed to opening in frame wall 10, the shaft piles in front of the opening are raised and the cutting shoe is forced into the ground, followed by sections of the conduit. The cutter shoe 13 has a sealed bulkhead (not shown) having a window and a sealed opening for a worm conveyor. <IMAGE>

Description

SPECIFICATION Process and apparatus for making conduits with access shafts or excavations in ground by the direct pressure-driving method The invention relates to a process for making conduits, with access shafts or excavations, in ground containing ground-water, as described in the pre-characterising clause of Claim 1, and to an apparatus for performing the process.

In making conduits, with access shafts or excavations, in ground containing ground-water it has hitherto been necessary, in many cases, to lower the ground-water level, by pumping the water away, sufficiently so that the access shaft or excavation can be constructed, and the conduit pipe driven forwards with an open cutter-shoe on its nose, without it being necessary to use a pressure chamber. In other cases, where this method is not possible, it has been necessary to use a pressure chamber and a pressure lock between the leading end of the conduit pipe and the cutter-shoe.

The pressure in the pressure chamber has to be higher than the external water pressure, to keep the water out and, as specified in the official safety regulations, the operating crew can remain in the pressure chamber only for brief intervals at a time.

A further difficulty occurs in removing the waste, i.e. the ground removed, from the interior of the cutter shoe through the pressure lock and away through the installed sections of conduit pipe.

These difficulties considerably increase the cost of operations.

The intention in the present invention is to provide a process and an apparatus which makes it possible to drive conduits forwards by the direct pressure-driving method through ground containing ground-water at a considerably higher speed of advance than hitherto and without it being necessary to lower the water table, so that the cost of operations is reduced.

The problem is solved, according to the invention, substantially as described in the characterising portion of Claims 1 + 2. The apparatus used is characterised as described in Claims 3 to 7.

The invention has the advantage that in the construction of the access shaft or excavation, and subsequently in the construction of the conduit itself, no lowering of the water table is involved. A lowering of the water table is not only undesirable in itself but can result, particularly in built-up areas, in local subsidence of the ground, causing damage to structures both on the surface and below ground. The apparatus of the present invention allows the conduit to be driven forwards by a fully mechanised operation. The working crew do not have to remain in the interior of the pressurised cutter-shoe. The bulkhead has a window through which the working face can be inspected precisely by an operator stationed behind the bulkhead.The waste from the working face is removed continuously by the worm conveyor, whose forward end picks up the waste at the level of the sole, i.e. the under surface of the advancing conduit pipe, without interruption of the forward-driving operations. It is only when the cutter-shoe encounters an obstruction that it can become necessary for personnel to enter the interior of the cutter-shoe, forward of the bulkhead. The inspection window in the bulkhead can be opened and suction lances pushed through sealed openings provided in the bulkhead and thrust forwards into the ground in front of the cutter-shoe, to lower the water level temporarily in that region.

A preferred example of an apparatus for performing the process of the invention is represented diagrammatically in the drawing, in which: Figure 1 is a vertical longitudinal section through an access shaft.or excavation after a cutter-shoe and an electro-hydraulic ram-press have been lowered into place for advancing a conduit pipe by the direct pressure-driving method through ground containing ground-water.

Figure 2 is a plan view of the access shaft or excavation, as seen in the direction of the arrow II in Figure 1.

Figure 3 is a vertical cross section taken in the plane Ill-Ill of Figure 1.

Figure 4 is a vertical longitudinal section through the shaft or excavation after several sections of conduit pipe have been advanced through the ground containing ground-water.

Figure 5 shows, drawn to a larger scale, the detail circled at V in Figure 4.

Figure 6 which is drawn to a larger scale, is a vertical longitudinal section through the leading end of the conduit pipe, showing also the cuttershoe during its forwards-driving through the ground containing ground-water.

Figure 7 is a vertical cross-section taken in the plane VIl-VIl of Figure 6.

As shown in the drawing, before beginning with the advancing of the conduit pipe through the ground there is first made an access shaft 1 , or an excavation, by driving walls of sheet-piles 3 into the ground 5 to below what will be the bottom 4 of the shaft, each individual sheet-pile being sealed water-tight to its two neighbours. Then the ground enclosed by the sheet-pile walls 2 is excavated, first down to the ground-water level 6 and then under water, i.e. with a constant inflow of ground-water, down to the bottom 4 of the shaft.

When excavation has reached the bottom 4 of the shaft, a concrete sole 7 is formed, under water, using a concrete which sets well under water. When the concrete sole 7 has hardened, the water in the shaft 1 is pumped out.

After the water has been removed, a press-pan 8, i.e. a support for an electro-hydraulic ram-press 16, is formed by pouring concrete over the sole 7.

Adjacent the sheet-pile wall 2 in the direction in which the conduit pipe is going to advance, there is formed a frame-wall 10 of concrete containing a circular access opening 11 whose inner periphery is furnished with an annular seal 12 (Figure 5) of an elastomeric material. The seal 12 is a lip-seal of the known kind, arranged to cooperate with the outer surface of a cutter-shoe 13, and subsequently with the outer surface of the conduit pipe 14, which follows the cutter-shoe 13 during the advancing of the conduit pipe 14 through the ground. The pressure of the ground-water thrusts the lip of the seal against the surface of the cuttershoe, or of the conduit pipe, preventing groundwater from leaking (from the right towards the left) into the access shaft 1.

The upper portion of the cutter-shoe 1 3 has a scoop-like projecting nose 1 5. Before the advancing of the conduit pipe begins, the cuttershoe 1 3 is lowered into the shaft 1 and positioned on the press-pan 8 forward of the electrohydraulic ram-press 16, a thrust-piece 17 being interposed between the two. The cutter-shoe 1 3 is then pushed forwards through the circular access opening 11 of the frame-wall 10 until the nose 1 5 of the cutter-shoe 13 comes up against the sheetpiles 3, and so that the outer peripheral surface of the cutter-shoe 1 3 is fully sealed, all the way around, by the flexible annular lip-seal 12.With the cutter-shoe in this position, its nose up against the sheet-pile wall 2, several of the sheet-piles 3, as many as is necessary, are raised sufficiently to clear the access opening 11 in the frame-wall 10, whereupon the cutter-shoe 13, followed by a section of conduit pipe, is pushed through the access opening 11 the flexible annular lip-seal 12 preventing ground-water from leaking into the access shaft 1.

As shown in Figures 6 and 7, the cutter-shoe 13 comprises a concrete tube 1 8 against whose trailing edge rests an inwards-directed steel thrust-ring 19. Thrusting forwards against the thrust-ring 1 9 are several hydraulic control cylinders 20, whose trailing ends take support against the leading edge of the section of conduit pipe 14 which follows the cutter-shoe 1 3. The function of the control cylinders is to adjust the cutter-shoe 1 3 in position, either keeping it strictly horizontal or giving it a small directional angle, depending on the requirements.

The cutter-shoe 1 3 has an external steel jacket 21 which extends all the way from the forward steel cutting edge to axially behind the leading edge of the conduit pipe 14, which a tubular skirt 22 of the steel jacket 21 surrounds and contains the leading end of the conduit pipe 14.

Fixed to the inwards projecting flange 23, which can if desired be an integral portion of the thrust-ring 19, there is a 2-piece bulkhead 24 which is sealed watertight in contact with the flange 23.

The bulkhead 24 (Figure 7) comprises two half plates 25 and 26 in the form of semicircular segments, one of the half-plates overlapping the other by a raised edge where they meet each other. The upper half-plate 25 contains an inspection window 27, which can be opened if necessary and is equipped with a lamp 27a. The lower half-plate 26 contains an opening 28 partly covered by a preferably flexible cuff-plate 28a through which passes, supported by the cuff-plate 28a, a tubular worm conveyor 29 for removing the waste, the flexible cuff-plate forming a watertight seal.The tubular worm conveyor 29 slopes downwards in the forward direction, so that its forward end, i.e. its intake end, reaches down, in the interior of the cutter-shoe 13, to the level of the sole (the under-surface) of the advancing conduit pipe 1 4. The rear end (the delivery end) of the inclined tubular worm conveyor 29 is situated above a delivery shaft 31, to whose upper end the conveyor 29 is connected by a tight seal. The delivery shaft 31 is arranged to deliver the waste picked up by the conveyor 29 to a continuous conveyor, or to a waste-waggon 32.

Each half-plate 25,26 of the bulkhead 24 has, near its periphery, several connections 33 (Figure 7) for admitting compressed air into the forward portion 1 3a of the cutter-shoe 13, forward of the bulkhead 24, each connection.33 having a valve 34 (Figure 6). And each half-plate 25, 26 has several further openings 35, apart from those for the window 27 and for the worm conveyor 29, to allow suction lances 36, one of which is represented diagrammatically in Figure 6, to be temporarily inserted in a sealed manner for lowering the water level in the interior 1 3a of the cutter-shoe 1 3 when an obstruction is encountered.

In a preferred version of the invention the worm conveyor 29 delivers the waste through a cellwheel lock 38 of the known kind mounted on a cover 37 which, in turn, is mounted either on a receiver for a continuous conveyor or on a wastewaggon 32, the cover 37 being clamped in place.

Claims

1. A process for pressure driving conduits in ground beneath the water table in which an access shaft is made by driving sheet piling into the ground to form watertight shaft walls, excavating the ground between the walls, forming a support at the bottom of the shaft for a hydraulic press and, by hydraulic pressure, driving conduit piping into an exposed ground surface in a wall of the access shaft and through the ground, characterised in that after reaching the water table, the access shaft is excavated with inflow of ground water permitting the water table level to be maintained in the access shaft, a watertight concrete sole is formed at the bottom of the access shaft using an underwater-setting cement, ground water within the shaft is removed therefrom, a concrete frame-wall is constructed against a wall of the shaft, the frame-wall having an access opening provided with an annular lip seal for sealing against the periphery of conduit piping as it is driven therethrough, some of said sheet piling is raised to clear said access opening, and said conduit piping is hydraulically driven through said access opening and into the ground led by a cutter shoe water-tightly secured to the leading end of the piping.

2. Process for making conduits with access shafts or excavations in ground containing ground-water and using the direct pressuredriving method, the process comprising the following steps: in the first step of the process the wall structure for the access shaft or excavation is made by driving sheet piles downwards into the ground to below the intended bottom of the access shaft or excavation, each sheet pile being sealed watertight against its two neighbours; then the ground between the walls is excavated; in the next step there is formed on the bottom of the shaft or excavation a concrete press-pan for supporting a hydraulic press; finally the conduit pipe is driven forwards by hydraulic pressure through the face-wall of the access shaft or excavation and through the ground; the process being characterised in that: after reaching the ground-water level 6 the access shaft 1 is excavated under water, i.e. with a continuous inflow of ground-water, permitting the groundwater level to be maintained in the interior of the access shaft 1; after excavation down to the intended bottom 4 of the shaft 1 there is formed on the bottom a watertight concrete sole 7 using cement which sets well under water; after the concrete sole 7 has hardened; the water is pumped out of the shaft; then there is formed on the concrete sole 7, between the sheet-pile walls 2, a concrete press-pan 8 for supporting the hydraulic press, and then there is constructed, adjacent the sheet-pile wall 2 in the intended direction of advance 9 of the conduit pipe 14, a concrete frame-wall 10 containing an access opening 11 whose inner edge is equipped with an annular lip-seal 12 of elastomeric material for making a seal with the peripheral outer surface of the conduit pipe 14; after that, several sheet piles 3, as many as is necessary, are raised to clear the access opening 11, whereupon a cutter-shoe 13 is hydraulically thrust forwards through the access opening 11, and forwards through the ground, the cutter shoe 13 being followed by a section of conduit pipe 14, the cutter-shoe 13 being sealed watertight against the conduit pipe 14.

3. A cutter-shoe for use in the process of Claim 1 or 2, such cutter-shoe comprising a tubular body equipped at its rear end with a radially-inwards directed thrust ring for transmitting the thrust of several control cylinders, the tubular body having an external jacket fast with a tubular skirt which axially overlaps the leading end of a following conduit pipe, and with a bulkhead containing an access opening, characterised in that the thrust ring at the rear end of the cutter-shoe 1 3 has a flange 23 projecting radially inwards beyond the inner surface of the tubular body 18, there being sealed watertight to the flange 23 a bulkhead 24 whose upper half 25 contains an operable inspection window 27, the lower half 26 of the bulkhead 24 having a sealed opening 28 through which passes an inclined worm conveyor 29 for removing waste, the worm conveyor 29 sloping upwards from its forward intake end to its rearward delivery end, the forward intake end of the worm conveyor being at the level of the sole (the under surface) of the tubular body 1 8, its rearward delivery end 30 delivering the waste through a sealed delivery shaft 31 to a continuous conveyor or to a waste-removal waggon 32.

4. Apparatus for performing the process of Claim 1 or 2, with a cutter shoe comprising a tubular concrete body equipped at its rear end with a radially-inwards directed steel thrust ring for transmitting the thrust of several control cylinders, the tubular concrete body having an external steel jacket with a tubular skirt which axially overlaps the leading end of the following conduit pipe, and with a-bulkhead containing an access opening, characterised in that the thrust ring at the rear end of the cutter-shoe 13 has a flange 23 projecting radially inwards beyond the inner surface of the concrete body 1 8, there being sealed watertight to the flange 23 a bulkhead 24 consisting of at least two parts, its upper half 25 containing an inspection window 27, which can be opened when necessary, the lower half 26 of the bulkhead 24 having a sealed opening 28 through which passes an inclined worm conveyor 29 for removing waste, the worm conveyor 29 sloping upwards from its forward intake end to its rearward delivery end, the forward intake end of the worm conveyor being at the level of the sole (the under surface) of the conduit pipe 14, its rearward delivery end 30 delivering the waste through a sealed delivery shaft 31 to a continuous conveyor or to a waste-removal waggon 32.

5. Apparatus as claimed in Claim 3 or 4, characterised in that the bulkhead 24 consists of two half-plates 25, 26 overlapping horizontally where they meet, the plates 25, 26 having connections 33 with valves 34 for admitting compressed air to the interior of the cutter-shoe 13 forwards of the bulkhead 24.

6. Apparatus as claimed in Claim 5, characterised in that the two half-plates 25, 26 of the bulkhead 24 also contain, in addition to the opening for the window 27 and the sealed opening 28 for the worm conveyor 29, further sealed openings 35 for inserting suction lances 36 for temporarily lowering the water level in the cutter-shoe 1 3 when an obstruction is encountered.

7. Apparatus as claimed in any of Claims 3 to 6, characterised in that the delivery shaft 31 of the worm conveyor 29 has a cell wheel lock 36.

8. A process for pressure-driving conduits substantially as herein described.

9. Apparatus for use in pressure-driving conduits substantially as herein described.