GROUTING METHOD

Abstract: A method of grouting the annular space around a new pipe, or a liner for an existing pipe, within, for instance, a sewage or water mains, involves locating within the new pipe or liner apparatus (3) having a drilling means (21), a grout injection means (22) and means (27) for feeding grout, or components therefor, to the injection means. A lateral connection may be sealed off and grout pumped into the annular space until it re-enters the pipe or liner via a tell-tale hole (33), a TV camera being used to monitor the operation.

Description: GROUTING METHOD The present invention relates to an improved method for filling the space between the outer wall of a sewage or water mains, and the surrounding ground with grout or other suitable material. There are several methods of replacing an existing mains, these methods including either fracturing or excavation of the existing mains and replacement by a new mains, or lining of an existing mains. With any such method, it is necessary to seal the annular space between the new mains and the surrounding ground or between the liner and the existing mains with grout or other suitable material in order to stop point loading, to prevent ingress of material such as water into this annular space, thus preventing ground erosion resulting from passage of ground water into the space between the mains and the ground. One such known method of mains replacement is directed towards renovation of sewage mains and involves taking small lengths of pipe up a sewer separately and building up the new sewage mains section by section. The method comprises passing a first length of pipe along the sewer from a remote control station to a predetermined starting position within the sewer to form a first length of new mains, and subsequently repeating the steps of passing a further length of pipe along the sewer from the control station to a position where the further length of pipe abuts the previous section of pipe, and forming a permanent joint between them to extend the new mains, all the steps being controlled from the control station. The method of permanently jointing two adjacent pipe lengths, in the case of thermoplastic pipes, may be induction fusion welding, as disclosed in European patent application No 809006026. This method uses an inductive coil which is used to induce a current in an electrically conductive material bonded to one of the sections of replacement mains which melts the thermoplastic pipes to weld them together. The inductive coil is carried on an inflatable bag which may be positioned within the new mains so that the coil and the electrically conductive material are aligned, thus allowing inducting welding to take place. After the joint between the further length of pipe and the previous length of pipe has been effected, the annular space between the further length of pipe and the surrounding ground is filled with grout, the grouting being effected and controlled at the control station. One known method of carrying out such grouting is by use of a grouting pump which is small and may be carried up the sewer within each new pipe section to be inserted. Before insertion, each pipe section has drilled in it a tiny hole having connected to it a nipple with a weakened portion. Before insertion of the pipe within the sewer the grouting pump is placed within the pipe section with a tube leading from it to the nipple. After grouting has been completed the grouting pump is pulled away from the grouting site, the weakened portion of the nipple breaks and the grouting pump may then be removed from the sewer. It is the purpose of the present invention to provide an improvement method of grouting the annular space between the outer wall of the new pipe or liner and the surrounding ground or existing pipe, the method including drilling grout injection holes from inside the main. According to the present invention there is provided a method of grouting the annular space around a new pipe or liner for an existing pipe, the method comprising locating within the new pipe apparatus having a drilling means, a grout injection means, and means for feeding grout to said injection means, the method further comprising drilling at least one hole in the new pipe or liner and injecting grout through the hole into the annular space to be grouted. Preferably the method includes altering the drilling means and grouting injection means from a first condition in which both the drilling means and the grout injection means are remote from the inner wall of the new pipe or liner, to a second condition in which the drilling means is adjacent the inner wall of the pipe or liner whilst the grout injection means remains remote from said wall, drilling a hole in the wall, altering the drilling means and grout injection means from said second condition to a third condition in which the drilling means is remote from said wall and the grout injection means is aligned with the drilled hole and forms a seal around the drilled hole, injecting grout through said grout injection means, and altering the drilling means and the grout injection means back to its first condition. With any method of mains replacement, accommodation has to made in the replacement pipe for connection with a number of conduits joining the mains, these being known as laterals. Therefore any replacement pipe or lining of existing pipes will have to have a hole cut in it at the position of every lateral so that the connection between the lateral and the main sewer is not blocked. The location of the position of the lateral may be determined exactly and accurately by a method in which a close circuit TV enclosed within a measuring cage is pulled into the sewer. The cage includes a rotatable mirror which allows the camera to scan all around the sewer, and graduations along the cage show the longitudinal position of the camera and the graduated scale extending around the cage shows the radial position of the rotatable mirror. In combination with the use of a fixed reference point known as "datum fixing" established by inserting an. inflatable bag to abut the last piece of pipe inserted, the TV camera may be moved along the cage and the TV signals sent to a viewer outside the sewer. In this way both the longitudinal and radial positions of the lateral with respect to the fixed reference point may be found. The cage is then removed from the sewer leaving the inflatable bag having the fixed reference point in position in the last pipe. Using the known length of the pipe section to be inserted and the measurements obtained by the TV signals a hole is cut in the next pipe section to be inserted at the correct longitudinal and radial positions with respect to the fixed reference point. ' Once the cut pipe section is in position with the hole aligned directly beneath the lateral connection, the TV camera may then be removed from the sewer. The cut pipe section is then welded to the existing pipe section by a suitable method such as induction welding and following this the annulus around the pipe in the region of the lateral connection is grouted by passing an auxiliary grouting bag along the sewer to a position in the cut pipe, the grouting bag including a shuttering bag which is capable of being inflated and extending to protrude into the lateral connection thus sealing it off from the mains so that the annulus between the cut pipe and the surrounding ground or, in the case of lining an existing pipe, the annulus between the liner and the existing pipe, may be grouted. The grouting bag has outlets connected to the grouting pump, and the cut pipe includes two nipples having weakened portions, as described previously, one on either side of the cut hole. This method of grouting suffers from the disadvantage that drilling of the tiny holes in the pipe is time consuming and the nipples used for injecting the grout are not reusable. It is also the purpose of the present invention to provide an improved method of grouting the annular space between the replacement pipe or liner and the surrounding ground or existing pipe in the region of a lateral connection. Preferably, the method according to the first aspect of the present invention further comprises locating within the new pipe or liner for the existing pipe a lateral sealing means, altering said lateral sealing means from a first condition in which the sealing means is located within the body of the new pipe or liner, to a second condition in which the sealing means protrudes into a lateral conduit through a lateral connection hole cut in the pipe or liner, thus sealing the lateral conduit off, drilling at least one hole in the wall of the new pipe or liner, injecting grout through the hole, and altering the lateral sealing means from its second condition into its first condition. More preferably, a second hole is drilled in the new pipe or liner on the opposite side of the lateral connection from the first hole and grout is injected into the first hole until it appears at the second hole, to ensure substantially complete grouting around the lateral connection. Preferably the method includes using a close-circuit TV camera located within the new pipe or liner,.for monitoring purposes. According to the present invention there is further provided apparatus for grouting the annular space between a new pipe or liner and the surrounding ground or existing pipe, the apparatus comprising a drilling means, a grout injection means, a grout pump connected to said grout injection means, and means fo feeding grout to said injection means. Preferably the drilling and grouting means are arranged so that they may be adjusted from a first condition, in which both the drilling means and grout injection means are remote from the wall of the new pipe or liner to a second condition in which the drilling means is adjacent said wall whilst the grout injection means is remote from the wall, and adjusted from said second condition to a third condition in which the drilling means is remote from the wall and the grout injection means is adjacent the wall and is aligned with the drill hole, forming a seal around the hole, and from said third condition back to said first condition. Preferably the apparatus also includes a lateral sealing means which is adjustable from a first condition in which the lateral sealing means is located within the body of the new pipe or liner, into a second condition in which the lateral sealing means protrudes into a lateral conduit through a lateral connection hole cut in the pipe or liner, thus sealing the lateral conduit off. Preferably the drilling means, grout injection means, grout pump, means for storing the components of grout prior to mixing and the lateral sealing means are all capable of being mounted on a slidable member such that they may be pulled within a new pipe or liner using a cable attached to the slidable member. Preferably all the equipment is operable from outside the mains by elecropneumatic operating means, controlling by valves and motor drives. The drilling and grout injection means may be separate or combined, each being individually capable of being raised or lowered, such that axes defined by the directions of movement of the drilling and the grout injection means intersect at a point on the inner surface of the wall of the pipe or liner. Preferably the lateral sealing means comprises an inflatable bag fixed within a cylinder which is located within the pipe or liner, the cylinder being mounted on a platform which may be moved upwards into position and also may be rotated about an axis passing along the length of the mains so that the bag within the cylinder may be aligned with the lateral connection, the bag being connected to an air supply such that it may be inflated to protrude into the lateral, thus sealing it off. A secondary sealing arrangement may be provided around the bag for security and for lateral repairs. There may be mounted at any suitable point on the apparatus a close-circuit TV camera which monitors the drilling and grouting operation by relaying signals to a remote control station. A currently known grouting pump carries two containers which hold the components of the grout. Measured quantities of the component are drawn into measuring pistons which are controlled by an air logic system. The measured quantities of each components are then drawn into a mixing nozzle where the components are spun together rapidly to mix them thoroughly, and the grout so produced is fed from the pump through a tube into the grouting bag described previously. It is also the purpose of the present invention to provide a proportioning grout pump suitable for use with fast curing chemical grout, ie a few seconds curing time, the pump also including means for purging the pump and passages to keep them free of grout. Preferably, the method of the invention includes of mixing grout from two separate components, comprising controlling the delivery rates of each component to a mixing head, the ratio of the delivery rate of the two components being chosen according to the particular grouting requirements, mixing.,the two components together in the mixing head, and extruding the grout from the mixing head to the grout injection means. Preferably the method also includes feeding compressed air into the mixing head to create turbulance and hence aid mixing. More preferably, the method also includes purging the grout-containing passages after each or several grouting operations. According to a further preferred aspect of the present invention there is provided apparatus for mixing grout from the two grout components and pumping the grout to the grout injection means comprising two gear or piston pumps each connected to a chemical storage tank containing the grout components, said pumps being connected via feed pipes to a mixing head which is in turn connected by an outlet pipe to the grout injection means. Preferably the mixing head also has connected with it an air supply for creating turbulance within the mixing head to aid mixing. Preferably the mixing head also has a further air supply for purging the grout injection system. Preferably the apparatus also includes a plurality of pressure sensing devices on the component feed pipes sending signals to a remote station to indicate any build¬ up of pressure. The apparatus may be driven by compressed air, the speed of the pumps being governed by a flow control valve in the compressed air feedline. Preferably the flow control valve is operated at a remote station. The apparatus may further include a plurality of non¬ return valves on the air supply line in order to prevent grout components from entering the air supply system. It should be noted that the grouting procedure can be performed, by means of a surface pump, to feed the grouting materials from a remote station, thus providing an option to the use of a pump located within the pipe. According to a further preferred " aspect of the present invention there is provided a method of forming a temporary joint between adjacent lengths of new pipe or liner for an existing pipe prior to permanently joining adjacent pipe lengths and grouting, the method comprising bringing a first pipe length up to a second pipe length, said pipe lengths together having means to allow a mechanical lock to be formed between them, and forming a mechanical lock between said pipe lengths. Preferably the means for forming the mechanical lock comprises an outer sleeve at at least one end of the first pipe length, said outer sleeve having an annular recess cut into its inner surface, and an inner sleeve at at least one end of the second pipe length, said inner sleeve having a corresponding annular rim on its outer surface to lock into the recess of the first pipe length when the two pipe lengths are pushed together, the inner sleeve fitting within the outer sleeve. According to a further preferred aspect of the present invention there is provided a method of replacing or lining an existing pipe, comprising forming a temporary joint according to the third aspect of the present invention between a number of adjacent lengths of pipe, grouting at a number of different sites along the new pipe lengths, and forming a permanent joint between a number of adjacent lengths of pipe. Preferably the sections of new pipe are grouted before forming permanent joints between the sections, but it should be appreciated that this sequence of operations may be reversed. Embodiments in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 shows the apparatus in accordance with the present invention inserted within a mains with the lateral sealing means aligned with a lateral connection; Figure 2 shows the same apparatus as in Figure 1, with the lateral sealing means raised and the bag inflated and protruding into the lateral; Figure 3 shows the typical cross-sectional area of the reinstated lateral in accordance with the present invention of the drill and grouting means. Figure 4 shows the means of mixing the grout materials in accordance with the drill and grout means. Figures 5 and 5A show further arrangements of drilling and grouting means in accordance with the present invention; Figure 5B shows a further alternative arrangement of drilling and grouting means in accordance with the present invention. Figure 5C shows an alternative sealing arrangement for the drilling and grouting means shown in Figure 5B; Figure 6 shows an arrangement of the grout pump and chemical storage tanks in accordance with the present invention; Figure 7 is a schematic of a grout pump in accordance with the present invention; Figures 8A and 8B show an arrangement for temporarily joining sections of new mains prior to induction welding and grouting; and Figure 9 illustrates a device for securing a cable used to pull apparatus of the invention through the mains. With reference to Figure 1 apparatus in accordance l with the present invention is mounted on a slide 1 and may be pulled into a sewage mains which has previously been renovated using the technique described previously. A lateral sealing device shown generally at 3 is manoeuvred into close proximity of the lateral connection 4 to be reinstated. A tell-tale hole 33 is drilled through the new liner pipe at a predetermined distance from the lateral connection. Once the device is in position the internal sealing head 3A is raised into position to completely seal off the lateral opening, thus preventing the ingress of grout back into the pipe. This feature also serves to stabilise the device while performing the drilling and grouting operations. The whole arrangement is rotatable about an axis parallel to the longitudinal axis of the main pipe. A close circuit TV 15 is mounted on the apparatus for allowing the operations to be performed remotely. In operation, the apparatus is pulled along the mains until the lateral sealing device 3 is adjacent a lateral connection, as determined by the close circuit TV 15. It should be appreciated that the sequence of operations may be changed in order to allow for flexibility in achieving the finished result. An inflatable bag 6 is then inflated by means of an external supply of compressed air such that it protrudes upwards into the lateral, thus sealing it off (see Figure 2) . After the lateral has been sealed off, the drill unit 21 is raised and a hole is drilled in the side of the replacement pipe adjacent the lateral. After drilling is completed, the drill unit 21 is retracted and the grout injection ram 22 is raised until the sealing head 24 forms a seal around the previously drilled hole. Grout is then pumped through the hole, and this grout fills the annular space around the upper region of the replacement pipe adjacent the lateral connection. Pumping is continued until grout appears at the tell-tale hole 33 drilled previously into the pipe when the lateral hole was cut and a drip tray 35 may be included to catch any grout which falls from the hole 33. Referring to Figure 3, after the grouting is completed, the ram 22 is lowered, the bag 6 is deflated, and the whole apparatus may then be removed from the mains or slid to the next connection to be grouted. The whole operation of the apparatus is by means of a remote air supply and a remote electrical supply. With reference to Figure 4, the grout is preferably mixed in the mixing chamber, formed when the sealing head 24 is in contact with the inside wall of the pipe. A preferred method involves feeding compressed air via tube 149 into one of the two grout feed tubes 150, 151 prior to the convergence point in the sealing head 24. As previously explained, the chemicals are turbulated to achieve mixing and the pumping force from the groout pump injects the mixed grout through the pipe wall into the void between the liner and the existing sewer. More preferably, the method also includes purging the mixed grout into the vooid to allow for repeated drilling and grouting operations. Figures 5, 5A, 5B and 5C show alternative arrangements for the drilling and grouting unit. With reference to Figure 5, an arrangement is shown which is useful in cases where the pipe diameter is small. The grout is injected sideways through tubes 35 into a grout injection head 37 which in cross-section has the shape of a parallelogram. The head includes a sealing ring 39 which forms a seal against the pipe 41 around the region of the drilled hole 40. A separate drill unit 43 is angled so that its longitudinal axis intersects with that of the grout injection head 37 in a " central position within the hole 41. With reference to Figure 5A, in pipes of slightly larger diameter, the grout injection head 45 may take the form of a square block, the grout being injected diagonally through tubes 47. The drilling and grouting units shown in Figures 5 and 5A are operated by pneumatic rams controlled by solenoid valves. With reference to Figure 5B, the drill 49 moves vertically within a grout injection- head 51 which includes a sealing lip 39 and a grout non-return seal. The grout is pumped in along grout tube 53. The drill is located within a hollow shaft 55 sunk within the injection head 51. A pneumatic ram may push the hollow shaft up and down thus moving the drill up and down, or alternatively a quick spiral helix device driven by the drill motor 57 may be 5 included to push just the drill upwards to locate it against the pipe wall. A vertical rigid member 56 acts as a guide and support as the drill is raised and lowered. With reference to Figure 5C, the grout injection head 0 51 may include a tapered portion 52 which replaces the need for a separate sealing element. With reference to Figure 6 the grout pump 27 has an external electricity supply via line 59 and an air supply via line 61. The grout pump is fed from the chemical 5 storage tank 29 via two feed lines 63, 64. The chemical storage tank 29 includes a chemical filler cap 65, a pressurised air line 67 including a pressure gauge 69 and a pressure regulator 70. The air supply line may also include a pressure release valve 72 as a safety precaution 20 should pressure build up. A second air supply is fed to the grout pump 27 via line 61 for the purposes of air mixing and air purging. With reference to Figure 7 a grout pump in accordance with the present invention comprises two gear pumps 76 and 25 78 connected via a dual chain drive 80. Gear pump 76 is fed with one component of the grout mixture, typically resin, via feed line 82 from the chemical storage tank. Gear pump 78 is fed with the second component of the grout mixture, typically an isocyanate chemical, via feed lines 30 83. Both gear pumps 76 and 78- are driven via the chain drive 80 by a reduction gearbox 85 which is in turn driven by an air motor 87. The air motor 87 is remotely controlled by using a solenoid valve 77 and the speed of the pump is governed by a flow control valve to vary the 35 final delivery rate of the mixed grout. The gear ratio of the pumps 76 and 78 determines the relative rates of output of each pump. Both components are fed from the gear pump 76, 78 into a mixing head 79 via feed lines 89, 88. On each of these feed lines 89, 88 there is included a pressure control switch 90 having signal wires 91 leading to a remote operation console to indicate any changes of pressure in these lines. Three air supply lines 92, 93, 94 are included, lines 93 and 94 feeding directly to the mixing head 79 and each including a non-return valve 95 to prevent grout from entering the air lines. Lines 93 and 94 feed air to the mixing head 79 in order to create turbulance and so aid mixing. The head 79 may also include two non-return valves, 96, 97 at the entry of each of the feed lines 88, 89. An air supply 92 has a control mechanism 98 which may be operated by a solenoid valve to allow air purging of the mixing head and the grout injection device. With reference to Figure 8, an improved method of forming a temporary joint between adjacent sections of replacement pipe prior to induction welding uses an outer female portion 100 at one end of a section of replacement pipe, this portion having a part spherically cut groove 102 running completely around the annulus formed by the inner wall of the pipe section. A corresponding male section 104 has a part spherical protrusion 106 running around the outside of the pipe. The two pipe ends are in fact machined to a spigot and socket format and to a condition where an interference fit necessitates an end thrust on the pipe to close the joint firmly, thus forming a locking mechanism between the two sections of pipe. In this way all the pipe sections may be" temporarily locked together and grouting according to the present invention may be carried out along a number of joined lengths of replacement pipe, prior to induction welding of the joints between the sections. Alternatively the induction welding may be carried out prior to grouting. This may be achieved by including an induction welding band 108 and the outside of the male section 104, and a location band 110 on the inside of the female portion 100. This arrangement has the advantage that when the induction welding band is activated, the heating effects which occur tend to cause expansion of the male section 104 outwards towards the female section .100, thus forming a tighter joint. With reference to Figure 9, a device for securing a cable 18 used to pull the apparatus through the mains comprises a hollow rod 112 which accommodates a double cable 18. At one end of the rod 112 there is provided a stopper 116 which engages against the end of the rod 112, the cable 18 being threaded around the end of the stopper. Thus when the stopper is tightly fitted against the end of the rod, the cable is fixed in position.

Claims: CLAIMS : 1. A method of grouting the annular space around a new pipe or liner for an existing pipe, the method comprising locating within the new pipe apparatus having a drilling means, a grout injection means, and means for feeding grout to said injection means, the method further comprising drilling at least one hole in the new pipe or liner and injecting grout through the hole into the annular space to be grouted. 2. A method according to claim 1 characterised in that the method includes altering the drilling means and grouting injection means from a first condition in which both the drilling means and the grout injection means are remote from the inner wall of the new pipe or liner, to a second condition in which the drilling means is adjacent the inner wall of the pipe or liner whilst the grout injection means remains remote from said wall, drilling a hole in the wall, altering the drilling means and grout injection means from said second condition to a third condition in which the drilling means is remote from said wall and the grout injection means is aligned with the drilled hole and forms a seal around the drilled hole, injecting grout through said grout injection means, and altering the drilling means and the grout injection means back to its first condition. 3. A method according to claim 1 or claim 2 characterised in that the method further comprises locating within the new pipe or liner for the existing pipe a lateral sealing means, altering said lateral sealing means from a first condition in which the sealing means is located within the body of the new pipe or liner, to a second condition in which the sealing means protrudes into a lateral conduit through a lateral connection hole cut in the pipe or liner, thus sealing the lateral conduit off, drilling at least one hole in the wall of the new pipe or liner, injecting grout through a hole, and altering the lateral sealing means from its second condition into its first condition. 4. A method according to any of the preceding claims characterised in that a second hole is drilled in the new pipe or liner on the opposite side of the lateral connection from the first hole and grout is injected into the first hole until it appears at the second hole, to ensure substantially complete grouting around the lateral connection. 5. A method according to any of the preceding claims characterised in that the method includes using a TV camera located within the new pipe or liner for monitoring purposes. 6. A method according to claim 6 characterised in that the method includes mixing grout from two separate components, comprising controlling the delivery rates of each component to a mixing head, the ratio of the delivery rate of the two components being chosen according to the particular grouting requirements, mixing the two components together in the mixing head, and extruding the grout from the mixing head to the grout injection means. 7. A method according to claim 6 characterised in that compressed air is also fed into the mixing head to create turbulence and hence aid mixing. 8. A method according to claim 7 characterised in that, after grouting, grout-continuing passageways are perged by air and/or one of the components of the grout mix. 9. A method according to any of the preceding claims characterised in that the method includes forming a temporary joint between adjacent lengths of new pipe or liner for an existing pipe prior to. permanently joining adjacent pipe lengths and grouting, the method comprising bringing a first pipe length up to a second pipe length. said pipe lengths together having means to allow a mechanical lock to be formed 'between them, and forming a mechanical lock between said pipe lengths. 10. Apparatus for grouting the annular space between a new pipe or liner and the surrounding ground or existing pipe, the apparatus comprising a drilling means, a grout injection means, a grout pump connected to said grout injection means and means for feeding grout to said injection means.

Inventors: BROUGH IAN JAMES, JONES MICHAEL A, WESTERMAN GRAHAM, BROUGH, IAN, JAMES, JONES, MICHAEL, A., WESTERMAN, GRAHAM
Applicants: BRICKHOUSE DUDLEY PLC
Application year: 1986
Main classification: F16L55
IPC codes: F16L55