GB2268037A

GB2268037A - Laying fin drains.

Info

Publication number: GB2268037A
Application number: GB9213864A
Authority: GB
Inventors: Roger William Lewis
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-06-30
Filing date: 1992-06-30
Publication date: 1994-01-05
Anticipated expiration: 2012-06-30
Also published as: GB2268037B; GB9213864D0

Abstract

A trenching machine fitment 11 is provided for laying a length of fin drain 2, 3 within a trench cut by the machine. The fitment 11 comprises a support member 12, a trenching blade 15, and a pipe box 18. The pipe box 18 has spaced side walls 19, 20 for holding back the sides of the trench behind the trenching blade 15, a top opening through which the fin drain is feedable into the trench between the spaced side walls 19, 20 and a rear opening through which the fin drain is payed out behind the fitment. A guide member 28 is provided on the side wall 20 for guiding the fin drain through the pipe box 18 with the pipe portion 2 of the drain at the bottom of the trench and with the fin portion 3 of the drain extending substantially vertically upwards and to one side of the guide member 28. <IMAGE>

Description

"Fitments for Trenching Machines" This invention relates to fitments for trenching machines for laying a length of fin drain in the ground within a trench cut by the machine, and to methods of laying a length of fin drain.

The Department of Transports "Highway Construction Details", which provides guidance on standards for use in road construction, includes standards for so-called fin and narrow filter drains which are installed at the edges of roads to drain the portion of the road under the layer of tarmac. It has been found that, if this portion of the road is drained, the life expectancy of the road is drastically improved. Methods have been developed for rapid installation of such drains using specially adapted machines which simultaneously cut a narrow trench using a trenching chain and install the drain in the trench so formed.

Such installation methods are satisfactory so long as the road construction materials allow a trench to be dug without the sides of the trench collapsing.

However, sometimes very granular materials are used for the construction of the road, such as 30-lOOmm stone or sand or gravel, and with such materials it is impossible to dig a trench with vertical sides. If the conventional installation method is used with such materials, the resulting trench will be far wider than would otherwise be required, and it is very difficult to install the fin drain in the trench so that it is correctly laid in the ground, particularly since it is necessary to backfill both sides of the trench by hand simultaneously in order to support the fin drain in the correct attitude.

It is an object of the invention to provide an installation method, and apparatus for carrying out the method, which is particularly applicable for use in circumstances where the construction materials are very granular.

According to the present invention there is provided a fitment for a trenching machine for laying a length of fin drain in the ground within a trench cut by the machine, the fin drain having a lower pipe portion and a fin portion extending upwardly therefrom, the fitment comprising an elongate support member for attachment to the machine, a trenching blade mounted on a lower portion of the support member and adapted to be forced through the ground by the machine in the direction of the intended path of the fin drain in order to cut the trench for receiving the fin drain, a pipe box mounted on the lower portion of the support member so as to extend rearwardly of the trenching blade and having spaced side walls for holding back the sides of the trench cut by the trenching blade for a predetermined distance behind the trenching blade, the pipe box having a top opening through which the fin drain is feedable into the trench between the spaced side walls and a rear opening through the fin drain is payed out behind the fitment, and guide means for guiding the fin drain through the pipe box so as to cause the fin drain to extend along the trench with the pipe portion at the bottom of the trench and with the fin portion extending substantially vertically upwards, the guide means including a guide member for engaging an upper part of the pipe portion so as to guide the pipe portion towards the bottom of the trench whilst enabling the fin portion to pass to one side of the guide member.

It is to be understood that the terms "lower" and "upwardly" are to be considered as applied to the fin drain in its attitude when installed in the ground, and that the terms "rear" and "top" are to be considered as applied to the fitment when correctly orientated in use.

When such a fitment is used to install the fin drain in very granular materials, the sides of the trench collapse onto the fin drain as it is payed out behind the fitment, and this automatically results in the fin drain being supported in the ground in the correct attitude. In these conditions the fitment can be considered as only temporarily forming a trench in the vicinity of the pipe box, the trench being filled in behind the pipe box as it follows the trenching blade through the ground. The fact that the trench is cut simply by forcing a trenching blade through the ground may give rise to some ground heave leaving a slight mound in the vicinity of the trench cut, although such ground heave is not very apparent where the materials through which the trench is cut are very granular.

The guide member may be mounted on one of the side walls of the pipe box so as to project towards the other side wall of the pipe box leaving a gap between the guide member and said other side wall for passage of the fin portion. Preferably the guide member is located in the vicinity of the rear opening of the pipe box through which the fin drain is payed out behind the fitment, and the guide member is curved along its length in the direction in which the fin drain is fed through the pipe box.

The pipe box may include spacer means for spacing apart the side walls of the pipe box. Furthermore the side walls of the pipe box may have flared upper edges.

In addition the fitment may incorporate a gravel hopper by means of which gravel may be introduced into the trench above the pipe portion and to one side of the fin portion of the fin drain. The.gravel hopper may include a chute which extends downwardly adjacent a rear portion of one of the side walls of the pipe box leaving a gap between the chute and a rear portion of the other side wall of the pipe box for passage of the fin portion.

The invention also provides a trenching machine incorporating such a fitment.

The invention also provides a method of laying a length of fin drain in the ground, the fin drain having a lower pipe portion and a fin portion extending upwardly therefrom, the method comprising forcing a trenching blade through the ground in the direction of the intended path of the fin drain in order to cut a trench for receiving the fin drain, simultaneously feeding the fin drain into the trench between spaced side walls of a pipe box for holding back the sides of the trench cut by the trenching blade for a predetermined distance behind the trenching blade, and guiding the fin drain through the pipe box so as to cause the fin drain to extend along the trench with the pipe portion at the bottom of the trench and the fin portion extending substantially vertically upwards, an upper part of the pipe portion being engaged by a guide member so as to guide the pipe portion towards the bottom of the trench whilst enabling the fin portion to pass to one side of the guide member.

In order that the invention may be more fully understood, a preferred form of fitment in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a section through a fin drain; Figure 2 is a perspective view of the fitment; Figure 3 is a similar view to Figure 2, but with the gravel hopper removed; and Figure 4 is an end view of. a rear portion of the fitment.

Referring to Figure 1, the fin drain 1 (which is of type 6 as defined by the Department of Transport's "Highway Construction Details") comprises a lower pipe portion 2 and an upwardly extending fin portion 3. The pipe portion 2 incorporates a flexible perforated plastics pipe 4, and the fin portion 3 incorporates a plastics grid core 5, both the pipe portion 2 and the fin portion 3 being surrounded by a layer of geotextile material 6 which is stitched at its upper end 7. Figure 1 also shows the trench 8 within which the fin drain 1 is installed and the semi-circular trench bottom 9, as well as a layer 10 of gravel covering the pipe portion 2 at the bottom of the trench and the backfill material 14.

Referring to Figure 2, the fitment 11 comprises an elongate support member 12 having.a forwardly extending nose 13 at its lower end to which a detachable trenching blade 15 is fitted by means of an end piece 16 which extends over the end of the nose and side lugs 17 which are bolted to the nose. The trenching blade 15 has a width greater than the nose 13. Attached to the rear of the support member 12 is a pipe box 18 having spaced side walls 19 and 20 and a V-shaped bottom wall 21. The side walls have flared upper edges 22 and 23 and are maintained parallel by a spacer member 24 (see Figure 3).

As the trenching blade 15 is forced through the ground in the direction of arrow A by a tracked machine and/or a winch arrangement using a wire rope, the following pipe box 18 serves to prevent the sides of the trench so formed collapsing and enables the fin drain 1 to be fed manually from ground level into the trench through the pipe box 18, the sides of the trench collapsing onto the fin drain 1 as it is payed out from the rear of the pipe box.

In addition the fitment incorporates a gravel hopper 25 having a hopper part 26 into which gravel is introduced and a chute 27 by means of which the gravel from the hopper part 26 passes into the trench above the pipe portion 2 as the fin drain 1 is payed out behind the fitment in order to prpduce the layer 10 of gravel shown in Figure 1.

Figure 3 shows the fitment 11 with the gravel hopper 25 removed in order to show a guide member 28 which is provided for guiding the fin drain 1 through the pipe box 18 so as to position the fin drain within the trench with the pipe portion 2 at the bottom of the trench and the fin portion 3 extending substantially vertically upwards. Figure 4 shows the end view of the guide member 28. The guide member 28 is mounted on the side wall 20 and acts to engage the upper part of the pipe portion 2 so as to guide the pipe portion towards the bottom of the trench whilst leaving a gap 29 between the guide member 28 and the side wall 19 for passage of the fin portion 3.

Type 5 fin drain (which has no pipe in the bottom portion of the drain) can also be laid by this method, using a machine as described in Patent Application No. 2218176A.

Claims

1. A fitment for a trenching machine for laying a length of fin drain in the ground within a trench cut by the machine, the fin drain having a lower pipe portion and a fin portion extending upwardly therefrom, the fitment comprising an elongate support member for attachment to the machine, a trenching blade mounted on a lower portion of the support member and adapted to be forced through the ground by the machine in the direction of the intended path of the fin drain in order to cut the trench for receiving the fin drain, a pipe box mounted on the lower portion of the support member so as to extend rearwardly of the trenching blade and having spaced side walls for holding back the sides of the trench cut by the trenching blade for a predetermined distance behind the trenching blade, the pipe box having a top opening through which the fin drain is feedable into the trench between the spaced side walls and a rear opening through the fin drain is payed out behind the fitment, and guide means for guiding the fin drain through the pipe box so as to cause the fin drain to extend along the trench with the pipe portion at the bottom of the trench and with the fin portion extending substantially vertically upwards, the guide means including a guide member for engaging an upper part of the pipe portion so as to guide the pipe portion towards the bottom of the trench whilst enabling the fin portion to pass to one side of the guide member.

2. A fitment according to claim 1, wherein the guide member is mounted on one of the side walls of the pipe box so as to project towards the other side wall of the pipe box leaving a gap between the guide member and said other side wall for passage of the fin portion.

3. A fitment according to claim 1 or 2, wherein the guide member is located in the vicinity of the rear opening of the pipe box through which the fin drain is payed out behind the fitment.

4. A fitment according to claim 1, 2 or 3, wherein the guide member is curved along its length in the direction in which the fin drain is fed through the pipe box.

5. A fitment according to any preceding claim, wherein the pipe box includes spacer means for spacing apart the side walls of the pipe box.

6. A fitment according to any preceding claim, wherein the side walls of the pipe box have flared upper edges.

7. A fitment according to any preceding claim, wherein the fitment incorporates a gravel hopper by means of which gravel may be introduced into the trench above the pipe portion and to one side of the fin portion of the fin drain.

8. A fitment according to claim 7, wherein the gravel hopper includes a chute which extends downwardly adjacent a rear portion of one of the side walls of the pipe box leaving a gap between the chute and a rear portion of the other side wall of the pipe box for passage of the fin portion.

9. A fitment for a trenching machine, substantially as hereinbefore described with reference to the accompanying drawing.

10. A trenching machine incorporating a fitment according to any preceding claim.

11. A method of laying a length of fin drain in the ground, the fin drain having a lower pipe portion and a fin portion extending upwardly therefrom, the method comprising forcing a trenching blade through the ground in the direction of the intended path of the fin drain in order to cut a trench for receiving the fin drain, simultaneously feeding the fin drain into the trench between spaced side walls of a pipe box for holding back the sides of the trench cut by the trenching blade for a predetermined distance behind the trenching blade, and guiding the fin drain through the pipe box so as to cause the fin drain to extend along the trench with the pipe portion at the bottom of the trench and the fin portion extending substantially vertically upwards, an upper part of the pipe portion being engaged by a guide member so as to guide the pipe portion towards the bottom of the trench whilst enabling the fin portion to pass to one side of the guide member

12. A method of laying a length of fin drain in the ground, substantially as hereinbefore described with reference to the accompanying drawing.