GB1572252A - Method of laying pipes underground - Google Patents

Description

(54) METHOD OF LAYING PIPES UNDERGROUND (71) We, KABUSHIKI KAISHA KOMATSU SEISAKUSHO, a Corporation organised under the laws of Japan of 3-6, 2-chome, Akasaka, Minato-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to a method of laying pipelines underground, and particularly but not exclusively to a method of laying underground a pipeline of a comparatively small diameter for gas and water supply and sewerage systems and cables etc.

There has heretofore been employed the "Open Cut Method" for laying a pipeline underground which comprises the steps of excavating a continuous trench at a predetermined depth in the ground, laying pipeline to be laid underground on the bottom of the trench connecting them transversely, placing wooden slippers under the pipeline at a reference height set by stretching a string, fixedly securing the pipeline and the slippers by means of concrete blocks, and then filling back the excavated trench.This method is, however, disadvantageous in that it encounters various problems caused by such things as traffic, buildings etc. in cities and suburbs, legal restrictions for working area, hindrances such as pipelines already laid, and the necessity of destruction of com pleted roadbeds etc., and therefore a considerably high construction cost and a long period of construction are inevitably required.

To eliminate such disadvantages, a method of laying a pipeline of comparatively small diameter underground by propelling them directly in the earth has been developed and employed as an alternative to the open cut method.

Conventional methods of laying pipelines underground in this way may be broadly divided into three: namely, a method in which a pilot head is used as a guide unit so that a pipeline led by the pilot head may be pushed and propelled in the earth so as to consolidate the earth and sand through which the pipeline passes thereby laying the pipeline underground; a method in which a pilot head having a propelling function is used as a guide unit so that the pipeline led by the pilot head may be pushed and propelled in the earth so as to consolidate the earth and sand thereby laying the pipeline underground; and a method in which the earth and sand are excavated while the pipeline to be buried is directly pushed and propelled, and the excavated earth and sand are discharged through the pipeline towards the launching pit.

The first method is disadvantageous in that the straight drive or advance of a long pipeline depends on or is impaired by the configuration of the solid pilot head, changes in density of the earth and sand to be consolidated and pebbles scattered in the earth.

The method disclosed in the Japanese Patent Publication No. 19767/1974 in which a pilot head having a propelling function is employed is also disadvantageous in that the control of the direction of propulsion of the pilot head is difficult because the propelling function is limited only to straight drive or advance.

This method has a big advantage in that the propulsion resistance can be reduced substantially, but it has big disadvantages in that the direction of movement of the pilot head is largely influenced by changes in earth stratum and existence of pebbles, and therefore it may sometimes get out of the predetermined depth and raise the ground or get out of the predetermined course and damage pipelines already laid underground. For this reason, this method could not be applied in the past to sewerage system etc. which are required to be installed at a predetermined gradient and with high accuracy in the vertical plane because it is necessary to allow sewerage to flow by gravity in the systems.

Further, the latter method is disadvantageous in that the movement of the earth and sand within the pipeline to be laid underground renders the measurement and control of the direction of advance of the pilot head difficult, and the number of treatment steps is increased due to the necessity of discharging the excavated earth and sand and underground water towards the launching pit Therefore, provision of a launching pit having a large area or space is unavoidable, and also the operation is required to be effected under extremely unfavourable conditions.

The present invention has been devised in view of the above-mentioned circumstances, and has for its object to provide a method of laying a pipeline underground with a desired accuracy by employing a pilot head having a propelling function, a direction detecting function and a direction control function or an excavating function, so that the direction of the pilot head can be controlled when the propelling function of the latter is rendered operative and the pipeline can be laid underground with a low propulsion resistance by double-acting propulsion of jack means adapted to propell the pipeline in the earth and by the propelling function of the pilot head.

Where it is required to lay an underground pipeline having a diameter larger than that of the pipe led by the pilot head which has been laid underground, the pipeline of a small diameter already laid underground is employed as a guide pipeline and is followed and propelled by a one-stage or multistage earth consolidating head having a diameter corresponding to the pipeline of a larger diameter so that the pipeline led by the earth consolidating head may be pushed and propelled. When the one-stage or multistage earth consolidating head reaches the receiving pit, it and the guide pipeline can be recovered in the pit so as to complete the laying of the pipeline of a larger diameter underground.

According to the present invention there is provided a method of laying pipelines underground, comprising the steps of: (a) providing a launching pit and a receiving pit spaced a predetermined distance from the launching pit, (b) installing a pipe propelling device having a propelling jack in the launching pit, (c) propelling a pilot head in the earth by means of the propelling jack of said pipe propelling device, (d) allowing a hose and a cable for driving the pilot head to pass through the inside of a first pipeline to be laid underground which is led by said pilot head, and pushing and propelling said pipeline in turn in the earth by means of the propelling jack while controlling the direction of propulsion of said pilot head, and (e) recovering said pilot head in the receiving pit thereby completing the laying of the pipeline underground.

The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side elevational view showing the laying of pipeline led by a pilot head underground according to the present invention, Figures 2-1, 2-2 and 2-3 are side elevational views showing schematically a method of laying pipeline underground according to the present invention, Figure 3 is a plan view of a pipe propelling device, Figure 4 is a front view of the same, Figure 5 is a side elevational view of the same, Figure 6 is a sectional view of the same taken along line VI-VI in Figure 5.

Figures 7-1-a and b, 7-2-a and b, 7-3-a and b and 7-4-a and b are views for explaining steps of folding the pipeline propelling device, Figure 8 is a view for explaining the pipeline propelling device when an object already laid underground is exposed in a launching pit, Figure 9 shows reaction force holding plates mounted on the wall of the launching pit, Figure 10 shows detailed structure of the pilot head, Figure 11 shows the pilot head fitted with a protector means, Figure 12 is an enlarged view of Figure 11, Figure 13 shows the interconnection of the pipeline connected to and led by the pilot head, Figure 14 shows in detail the connecting portion shown in Figure 13, Figure 15 shows detailed structure of a pilot head employing a mud motor, Figures 16-1, 16-2, 16-3 and 16-4 show schematically the control of direction of the pilot head, Figure 17 shows a method of detecting the direction of the pilot head by projecting a reference light, Figure 18 shows a detector adapted to receive the reference light and send out a signal, Figure 19 shows a system according to the present invention in which the pipeline of a small diameter laid already underground is employed as a guide or pilot pipeline and the pipeline of a larger diameter led by a multi-stage earth consolidating head is laid underground by the action of the consolidating head, Figures 20-1, 20-2 and 20-3 show detailed construction of the multi-stage earth consolidating head and the operating conditions thereof, Figures 21 shows a further system according to the present invention in which the pilot pipeline is employed for discharging excavated earth, and the pipeline of a larger diameter led by the excavating head is laid underground by the action of the excavating head, Figure 22 is a longitudinal sectional view of the excavating head, Figure 23 is an enlarged view of the leading end of the excavating head shown in Figure 22, Figure 24 is a sectional view taken along line XXIV-XXIV in Figure 23, Figure 25 is a sectional view of another embodiment of the excavating head, and Figure 26 is a sectional view taken along line XXVI-XXVI in Figure 25.

Figure 1 shows a condition in which predetermined lengths of pipes 2-1, 2-2 .... 2n follow a pilot head and are propelled in the earth by double-acting propulsive action of a propelling jack 3 and a pilot jack 25. The pipes are propelled or moved ahead from a launching pit 4 to a receiving pit 5 until the leading end of the pipe 2, reaches the receiving pit 5 thereby completing laying of all the pipes underground.

Installed within the launching pit 4 are a pipe propelling device 6, a reaction force holding plate 7, a measuring and reference light transmitter 8 and a control unit 9 so that the operator can operate the control panel of the control unit 9 in the launching pit 4 to enable him to control the whole system.

Further, the power supply unit 10 is installed on the above-ground part of the launching pit 4 so that it may supply fluid under pressure or electric unergy to the control unit 9.

The hose 14 for hydraulic fluid and the electric cable 11 connect the power supply unit 10 with the control unit 9 by way of connectors 12, 13, 15 and 16. The fluid under pressure and electric energy from the control unit 9 can be supplied to the propelling jack 3 and the pilot jack 1, respectively. The control unit 9 can supply fluid under pressure and electric energy to the pilot head 1 through hose 14' for hydraulic fluid, electric cable 11', notch formed on an adaptor 26 of the propelling jack 3 and the inside of the pipeline to be laid underground.

The hose and cable may be increased in length depending on the length of the pipeline to be laid underground, or they may be extended by connecting them by means of coupler for two or three lengths of the pipeline to be laid underground.

The reaction force holding plate 7 is suspended on an earth retaining plate 48 by a hook 17 attached to an wire 18.

Reference numeral 21 denotes a pipe saddle that is freely movable on rail 22 to assist the propulsion of pipe to be buried underground. Reference numeral 20 denotes an unit for detecting the direction of propulsion of the pilot head. The detector unit is adapted to read a deviation in scale of means of the measuring unit 8, for example, a transit instrument etc; or it serves as a reference light projector to automatically detect the direction of propulsion of the pilot head and indicate it on the control panel.

Reference numeral 19 represents expandable legs of the pipeline propelling device which enable it to be laid in level.

Further, the propelling jack 3 has a supporting saddle 27 which is movably carried through rollers 23 on the rails 22 and which is adapted for shifting at a predetermined pitch and, if required, clamped and unclamped.

Figure 2 illustrates schematically the procedure of laying a pipeline underground according to the present invention. Figures 2-1 and 2-2 show a condition in which when the pilot head 1 propelling underground is connected to and followed by a chain of pipes to be laid underground, the pilot jack 25 of the pilot head is extended in the ground so as to consilidate the earth, and then release the pilot jack pressure; and the rear part of the pipeline to be laid underground is propelled only by the stroke of the pilot jack by the action of the propelling jack 3 installed in the launching pit thereby effecting double-acting propulsion. When the pilot head 1 has passed through the earth and has reached the receiving pit 5 as shown in Figure 2-3 by effecting the operations shown in Figures 2-1 and 2-2 repeatedly, laying of a pipeline underground is completed.

Since the stroke of the propelling jack is usually smaller than the length of pipeline to be laid when effecting the operations shown in Figure 2-1 and 2-2 repeatedly, the supporting saddle 27 can be slid on rails 22 by the length of the pipeline to be laid and then clamped.

Figure 3 is a plan view of the pipe pro pelling device 6. Two rows of rails 22 located in parallel relationship can be assembled by means of connecting members 33 and legs 19. Each of the rails 22 has a plurality of positioning holes 30 formed therein which enable the propelling jack 3 to be shifted at a predetermined pitch and clamped. The supporting saddle 27 has also at least two holes 30' formed therein which correspond to the positioning holes 30 and which are engageable with them.

Reference numeral 31 denotes a pin adapted to be inserted through both holes 30 and 30' for positioning and clamping the propelling jack 3; reference numeral 26 indicates an adaptor which is replaceable depending on the diameter of the pipeline to be laid underground, and reference numeral 29 a notch in which is inserted a hose for transmitting hydraulic pressure or electric energy to the pilot head. Reference numerals 34 and 35 denote tensioning or stretching means fitted to the front and rear ends of the rails 22' for fixedly securing the pipeline propelling device within the launching pit, and it has a structure to be extended and contracted by pressurized fluid or mechanical means. Reference numeral 32 represents a stopper.

Figure 4 is a plan view of the pipe propelling device shown in Figure 3. The rails 22 have at least three pairs of legs 19 the height of which is freely adjustable. At least one pair of legs 19 is connected by means of the connecting member 33. The pipeline saddles 21 are carried through a roller 24 on rails 22 and have a downwardly extended bed which is provided with rollers 36, beds 37, and a roller 38 and stays 39 for holdinging the pipeline to be buried. The stays 39 can be adjusted in length depending on the diameter of the pipeline to be buried.

Reference numeral 40 denotes a sliding pad which may be replaced by a roller.

Figure 5 shows the side elevation of the pipe propelling device adapted to be in stalled in the launching pit for pushing and propelling the pipeline to be laid underground and carry the pipeline resting thereon as shown by imaginary line.

Figure 6 shows a section of one embodiment of legs 19 and the front view of the propelling jack 3, and the supporting bed 27 for the propelling jack is movably carried by the rails 22 and the rollers 23. The upper portion of each of the legs 19 is U-shaped, and the lower portion thereof is of a closed cylinder shape in section. Reference numeral 41 denotes a nut serving to adjust the degree of inward or outward extension of adjusting screw 42. Reference numeral 44 denotes a leg seat having a conical hole formed in the central part thereof in which a receiving cap 43 abuts against a spherical seat 45.

The adjusting screw 42 can be adjusted be rotating it by a wrench through the upper opening of the leg 19.

Figure 7 shows the plan and side elevation of the folded pipe propelling device.

Figures 7-1-a and 7-1-b show the pipe propelling device assembled in normal condition. If the pipe propelling device remains as it is, it can not be installed in the launching pit in case where the pipe already laid underground is projected into the pit. Such situation has frequently been experienced in practical operations, and so it becomes often necessary to install in the pit the pipe propelling device under semi-assembled condition.

In the first place, as shown in Figures 7-2-a and 7-2-b, the pipeline saddle and the propelling jack supporting bed mounted on the rails 22 are removed, and then as shown in Figures 7-3-a and 7-3-b, only one of the rails 22 is removed. Thereafter, the connecting members 33 with the legs 19 assembled therewith are rotated about the legs 19 mounted on the other one of the rails 22 so that the whole unit may be accommodated in the projected plane thereof. Therefore, the whole unit can be put in the launching pit as a compact unit. In other words, the pipeline propelling device can be installed in the pit and dismantled therefrom under least possible disassembled and assembled condition.

Figure 9 illustrates one embodiment of reaction force holding plates suspended on the earth retaining plate 48 by means of wires 18 and hooks 17. The reaction force holding plate may be formed in a single unit. However, in order to set the pipeline propelling device within the pit by means of a stretcher means, it is desirable to divide the reaction force holding plate into two sections and connect them by means of hinges 47 as shown. For it is not rationally possible to finish the earth retaining plate 48 or earth retaining wall forming the wall of the pit in a smooth plane. Therefore, when the reaction force holding plate is formed in a single unit, the surface area of the plate abutting against the earth retaining plate is limited.No serious problem is caused when the abutting surface is located outside the transverse pitch of the stretching means for the pipeline propelling means.

However, if the abutting surface is located inside it, stable arrangement of the stretching means can not be made and so it becomes impossible to ensure accurate and reliable operation. If the reaction force holding plate is divided into at least two sections, the above-mentioned abutting surface is always located outside the point against which the stretching means abuts so that the stability of the stretching means can be improved.

Further, when the reaction force holding plate is divided into two sections, hinges 47 may be employed to connect them as shown in the embodiment of Figure 9.

Figure 10 shows the internal structure of the pilot head having a casing 49 which can be usually divided into three sections, The casing 49 comprises a pilot jack unit "a", direction control unit "b" and a direction detector unit "c". The abovementioned three units can be interconnected by threadably engaging the casing unit themselves or by connecting bolts 85 through flanges, The pilot jack 25 comprises a cylinder 53, piston 71, a piston rod 75 and a piston ring 70, and is carried through a spherical bearing 50 and a ball bearing 51 by the casing 49.

Fluid chambers 72 and 73 are formed on both sides of the piston 71 within the cylinder 53 so that the pilot jack may be extended when the control unit 9 is rendered operative to permit fluid under pressure to flow through a hose 64 and a passage 74 formed in the piston rod 75 into the chamber 72. Stated briefly, the cylinder 53 extends with its inner bore portion sliding on the piston 70 and its outer surface sliding on the inner bore portion of the ball bearing 51. Further, the pilot jack may be retracted by permitting the flow of pressurized fluid through passage 74' into the chamber 73.

The piston rod 75 has in the rear part thereof a spherical seat 78 engageable with spherical seat 50 and is slidably fastened by means of a nut 79. Mounted on the leading end of the cylinder 53 is a cutter 54 fastened thereto by means of bolts to consolidate the underground earth and sand. The cutter has a recess 69 formed in the front part thereof for maintaining the direction of propulsion. The recess 69 should desirably be of a shape capable of minimizing the influence of changes in density of earth and gravel.

Our series of experiments proved that a flat recess is better than conical shaped one, and those having a recess as indicated by 69 and a cutting edge are desirable in particular. Further, the above-mentioned propelling jack means is not necessarily of a double acting type, and the same effect can be obtained by using a ram type singleacting propelling jack means.

Reference numeral 49' denotes a cover having a spherical bearing 51 and a sealing means 76 which are held between the cover and the casing 49 for preventing the intrusion of the earth and sand and water etc.

into the pilot head. Reference numeral 77 indicates a lubricant sealing part in which grease is charged. The trailing end 82 of the piston rod 75 of the pilot jack 25 thus formed is pivotally engaged through a bearing 56 with an oscillating bracket 55. The oscillating bracket 55 is pivotally engaged through a bearing 62 with the casing 49.

Further, the oscillating cylinder means 80 and 81 are pivotally carried by an annular member 58 in a plane at right angles to the longitudinal axis of the pilot head and at a phase difference of 90 degrees therebetween.

The oscillating cylinders 80 and 81 have respective piston rods the ends of which are pivotally engaged with the oscillating bracket 55.

Reference numeral 65 denotes a valve means adapted to manually or automatically change over the flow of hydraulic fluid by a signal sent by a direction detector 57 when fluid under pressure is supplied into the latter by the control unit 9. At that time, a predetermined amount of pressurized fluid is supplied through the valve means 65 and a conduit 83 into the cylinder means 80 and 81 so that the pilot jack 25 may be pivotted or oscillated about a point 52 in any direction in the plane extending at right angles to the longitudinal axis of the pilot head.

The detectors 63 and 63' are mounted between the annular member 58 and the oscillating bracket 55 at a phase difference symmetrical to the cylinder means 80 and 81 in the manner similar to the latter. In general, as the detectors, potentiometers are employed and serve to convert the stroke of propulsion into an electric potential which is sent in the form of a signal through wiring 84 to the control unit 9. Reference numeral 68 denotes a partition separating the direction control unit "b" from direction detector unit "c".

Next, the direction detector unit "c" is described below with reference to Figure 15. The detector unit described herein serves to mainly effect optical measurement and detection. Direction measuring means 57 includes a housing 86 having a transparent plate glass fitted in the front part thereof.

The transparent plate glass 87 has rectangular co-ordinates formed thereon and pitch circles formed about the origin of the latter at equal space intervals. Reference numeral 88 denotes a mirror which has pitch lines in the form of rectangular co-ordinates formed thereon and which is located in the rear part of the housing 86. Reference numeral 89 denotes a lamp which enables easy reading of a deviation in the above-mentioned pitch lines from the outside.

A deviation in the rectangular coordinates can be observed by means of a transit instrument 8 installed in the launching pit and the direction and extent of deviation may be obtained by calculation.

Inclinometer 59 may be used in combination with the direction detector unit so that the inclination of the pilot head relative to the longitudinal axis can be directly read by means of the control unit 9.

Further, an optical direction detector as shown in Figures 17 and 18 may be employed for the same purpose. The detector comprises a housing 92 having an opening in which is inserted a convex lens 91 having crossed pitch lines 91a formed thereon.

Mounted at the focal distance of the convex lens 91 is a light receiver means 94 which comprises a plurality of light receiver elements. The light receiver means 94 is connected with amplifier 96 by cable 95.

Reference numerals 93 denote lamps for enabling measurement to be made easily so as to focus the light projected from the outside on the lens 91. Reference numeral 98 denotes a reference ray projector employing helium laser rays etc. This detector is fixedly secured on the partition 68 and therefore changes its direction with the pilot head 1. When the pilot head deviates toward any direction relative to the reference light, any of the light receiver elements on the light receiver means 94 receives the light so that it is rendered conductive, and the electric current caused thereby is amplified by amplifier 96 so as to indicate the direction and amount thereof on the control unit.

Figure 17 schematically illustrates the abovementioned condition.

The pilot head 1 is constructed as mentioned hereinabove, and can achieve extremely accurate controls of the direction and a substantial reduction in propulsion resistance.

In order to improve the durability of the pilot head, an arrangement is made so as to prevent the intrusion of the earth and sand and water through the sliding components such as the sealing means 76, the bearing 51 and the pilot jack 25 mounted in the front part of the pilot head as shown in Figures 11 and 12. Some consolidated earth tends to break loose. In that case, when the pilot jack is extended so as to release the pressure in the chamber 72 and is propelled by the propelling jack, the sand and mud is permitted to intrude between the cutter 54 and the front end of the pilot head thereby causing breakage of the sealing means 76 and damages the sliding surface of the pilot jack 25. To avoid this it is desirable to mount protective flexible metal cover 99 on the rear part of the cutter 54 to form step portion 103 thereby preventing the intrusion of the earth and sand thereinto.

Reference numeral 101 denotes a sealing means adapted to slide on the outer periphery of the casing 49 of the pilot head.

The sealing means 101 has a groove which is formed on the outer periphery thereof and which is engaged with an annular projection 100 formed as an integral part of the cover 99.

Such arrangement permits the cover 99 to move in response to the extension and contraction and oscillation of the pilot jack 25.

Figure 15 shows another embodiment of the pilot head which can be used for excavation and in which a mud motor is employed in place of the pilot jack of soil consolidation type. The pilot head of this type is mainly used for hard soil strata, and is adapted to drive the motor by supplying fluid such, for example, as water under pressure from an outside fluid source.

Hose 113 is used for supplying fluid under pressure through a passage 106 into the driving unit 105 of mud motor 104 thereby actuating the latter. Further, the fluid used for driving the mud motor 104 will jet through a passage 109 formed in the driving shaft 108 and passage 110 which opens in the front surface of the cutter 111 to the outside.

Such arrangement will reduce the resistance of the earth and sand on excavation and cool off the cutter, and mix at the same time, the excavated earth with the fluid jet forming a mixture which is in the form of sludge. The sludge is driven through passage 112 which opens in the front end of the pilot head and is discharged through hose 114. In this type of pilot head, a circulation system may be employed for separating the sludge into fluid and solid substances outsides the device and recirculate the fluid in the mud motor. Other component parts of this pilot head are the same as those of the pilot head described above.

Figure 16 schematically illustrates the manner of controlling the direction of the above-mentioned pilot head. Figure 16-1 shows a case where the pilot head being propelled into the earth is directed downwards due to difference in the nature of earth or collision with rock in the earth.

Such change in direction of the pilot head can be read or detected by means of the measuring unit so that the control unit 9 may send an instruction immediately to direct the pilot jack 25 upwards as shown in Figure 16-2, extend the pilot jack as shown in Figure 16-3 so as to enable the pilot jack to make straight advance by means of the propelling jack 3. Such operations are required to be effected repeatedly until the straight advance of the pilot head is assured.

Figure 16 is merely for illustration and is shown in exergerated form; it is not necessary to make such large correction in practical application.

Figures 13 and 14 show the manner of connecting the units of pipes to be laid underground which are connected to and led by the pilot head; but such connection is not always necessary. In brief, depending on the purpose for which pipelines to be buried in the earth is used, the pipes may be loosely connected by merely laying them underground only by permitting them to abut against or by means of adaptors and propelled. However, where there are encountered changes in earth stratum or remarkable changes in the earth density when pipes are being propelled in the earth, resistance to propulsion will naturally change and will interfere with the propulsion when a long pipeline is laid underground.

In such case, the resistance to the pipe being propelled in the earth can be reduced by driving the propelling jack in the direction reverse to the direction of propulsion.

Further, regarding concrete pipes having accurate right angles kept in the terminal faces thereof, it is difficult to obtain a predetermined accuracy in propulsion and to prevent wave motion of individual pipes being buried relative to the longitudinal axis of the whole line only by allowing individual pipes to abut against each other. As a result of various experiments undertaken, it was found out that a satisfactory result could be obtained by providing both ends of the pipes 2 to be laid underground with lugs 115 and connecting the latter by means of a bolt 117 and a nut 118. In that case, better result can be obtained by interposing the elastic tube 116 and the annular member 119 between the lugs and fastening them relatively loosely as compared with the case of fastening the bolt and nut tightly.

This may be due to the fact that when the bolt and nut are fastened tightly, the degree of right angle in the end faces of the pipes acts to reduce the effect of correction of the direction of pilot head, whilst when fastening them loosely, the pipes will have a degree of freedom in response to the correction of direction thereof.

A method and device for laying underground a pipeline by connecting it to and led by a pipeline of a smaller diameter which is led by the pilot head will now be described below. The pipeline of a smaller diameter will be referred to as "guide or pilot pipe (or pipeline)" hereinafter.

Referring to Figure 19, the multi-stage earth consolidating head 120 following the guide pipeline 2 is pushed by the action of the propelling jack 3 so as to be laid under ground. After that, following the multi-stage earth consolidating head 120 pipeline 121 is laid underground. And then hose 122 for fluid under pressure is inserted in the pipeline 121 and is connected to a connector 123. In the first place, the smallest diameter stage of the multi-stage earth consolidating head is propelled underground while it is consolidating the earth, and then the next larger diameter stage is propelled underground with the smallest diameter stage still being pushed out.Such operations are effected successively, and when all the stages have been pushed out, earth consolidation is effected to widen the passage for the pipeline 121 to be laid underground by releasing the fluid under pressure in all the stages of the multi-stage head 120 and manipulating the propelling jack 3 so that the pipeline 121 may be propelled underground with less resistance. The guide pipes are recovered in turn in the receiving pit. When the multistage earth consolidating head 120 is finally recovered in the receiving pit so that the leading end of the pipeline 121 reaches the latter, laying operation of the pipeline 121 underground is completed.

Figure 20 shows the detailed structure of the multi-stage earth consolidating head 120 and its operating conditions. Reference numeral 124 denotes a guide head having at its leading end a guide portion to be inserted in the rearmost one of the leading pipe 2.

The first stage earth consolidation is effected by the tapered face 130 extending from the guide portion to the cylindrical member 126 of a diameter larger than that of the former.

Reference numeral 125 denotes a piston which is accommodated within the first stage cylinder 129. When fluid under pressure is introduced into the hydraulic fluid receiving chamber 128 through passage 131, hose 132 and connector 133, the cylindrical member 126 is moved by the stroke of the piston 125 ahead of the second jack 134. When fluid under pressure is supplied into the hydraulic fluid receiving chamber 139 through hose 135, connector 136 and passage 138 under such condition, because of piston 140 formed as an integral unit of the first stage cylinder 129 being fixedly secured to a casing 141, a cylinder 137 is moved ahead until it abuts against the rear shoulder of piston 140 while the surface 142 of the second stage jack 134 is pushed underground so as to effect its earth consolidation. Connected to the rear end of casing 141 is pipeline 121 to be laid underground.Figure 20-1 shows a condition wherein no fluid under pressure is supplied into the chambers. Figure 20-2 shows a condition wherein the first stage jack is propelled. Figure 20-3 shows a condition wherein the second stage jack is propelled with the first stage jack left under a hydraulically locked condition. By thus effecting earth consolidation in multi-stages, the earth consolidation can be effected without remarkable resistance so that the pipeline 121 can be propelled underground very smoothly. Further, depending on the nature of the earth through which the pipelines are propelled, several stages of jacks may be selectively operated. For example, in Figure 20, if the first stage head is not rendered operative, only the second stage head 134 is operated so that both the first and second stage earth consolidation may be effected at the same time.

Figure 21 illustrates another example in which the excavating head 143 is employed in place of the multi-stage earth consolidating head shown in Figure 19. In this example, the guide pipeline 2 which is already laid underground is used as a guide when excavating a hole of a large diameter underground, and the arrangement is made in such a way that the removed earth 145 is carried into the receiving pit 5 by means of the screw conveyor 144 which extends inside the guide pipeline 2 and is adapted to be driven by the aforementioned excavating head. Connected to the excavating head 143 is the hose 122 which extends into the pipeline 121 to be laid underground following the excavating head and which is connected to a fluid supply source by way of the connector 123 so as to drive the excavating head.The propelling jack 3 is adapted to be operated depending on the amount of excavation made by excavating head 143 so that the guide pipeline 2, the screw conveyor 144 and the excavating head 143 may be recovered in the receiving pit 5.

The propelling jack 3 completes its propulsion when the leading end of the pipeline 2 to be laid underground reaches inside the receiving pit 5. The screw conveyor 144 has a length nearly equal to that of the guide pipeline, and its intermediate connections can be attached and detached easily by means of couplers.

Figure 22 shows the internal structure of excavating head 143. The excavating head comprises a casing 146 adapted to be divided into a plurality of sections, a hydraulic motor 149 mounted within the casing and being adapted to be driven by fluid under pressure supplied by hose 147 and discharged through hose 148, said hydraulic motor having an output shaft 150 which is engaged with a coupling 151, a conveyor or driving shaft 152 which is engaged with the coupling and is adapted to directly transmit the rotation of hydraulic motor 149 to screw conveyor 153. The coupling 151 has a gear 154 fitted thereto which is engaged with a gear 155. The gear 155 is adapted to drive through a shaft 156 having fixedly secured thereto a gear 157. The gear 157 is engaged in turn with ring gear 158. The ring gear 158 is coupled with a cutter driving shaft 159.The cutter means 161 is adapted to be rotated in the direction reverse to the directtion of rotation of the screw conveyor through a cylindrical bearing and a thrust bearing mounted between the casing 146 and housing 160.

The housing 160 is fixedly secured to partition 162 which carries the conveyor shaft 152 rotatably. Further, the excavating head 143 has at its front end a guide tube 163 for connecting thereto the guide pipeline 2. The guide tube 163 has an inlet port 164 through which the earth and sand excavated by cutter 161 is directed towards the screw conveyor 153 and the guide pipeline connecting portion 165.

Connected to the front of the thus constructed excavating head 143 are the guide pipeline 2, and the screw conveyor 144 accommodated within the latter, and also connected to the rear of the excavating head 143 and the pipeline 121 to be laid underground. Using the guide pipeline 2 as a guide, the propelling jack 3 is propelled in response to the progress of excavation of the excavating head 143 so as to lay the pipeline 121 underground.

Figure 23 shows the detailed structure of a cutter means 161. The cutter means 161 is connected to the cutter driving shaft 159 by means of a bracket 167. The cutter means 161 is of a trapezoidal shape in side elevation and has an inclined surface to which are fitted a plurality of cutter blades 166.

The earth and sand excavated by the rotation of the cutter means 161 drops through the inlet port 164 into the conveyor chamber 168 and is then sent by the screw conveyor 153 into leading pipeline 2.

Figure 25 shows a further example having an enlarged earth and sand accommodating chamber 171 in the cutter means 161 so as to make the inlet port 164 of the guide tube 163 larger and also having a scraper 170 mounted in the outer periphery of the inlet port so as to ensure efficient feeding of the excavated earth and sand into conveyor chamber 168.

Figure 26 shows a section taken along XXVI-XXVI in Figure 25 for the purpose of explaining the relationship between the scraper 170 and the inlet port 164 for excavated earth and sand.

The excavating head described herein with reference to Figs. 21 to 26 is described and claimed in our divisional application No. 79 26611 Serial No. 1 572 253.

WHAT WE CLAIM IS: 1. A method of laying pipelines underground, comprising the steps of: (a) providing a launching pit and a receiving pit spaced a predetermined distance from the launching pit, (b) installing a pipe propelling device having a propelling jack in the launching pit, (c) propelling a pilot head in the earth by means of the propelling jack of said pipe propelling device, (d) allowing a hose and a cable for driving the pilot head to pass through the inside of a first pipeline to be laid underground.which is led by said pilot head, and pushing and propelling said pipeline in turn in the earth by means of the propelling jack while controlling the direction of propulsion of said pilot head and (e) recovering said pilot head in the receiving pit thereby completing the laying of the pipeline underground.

2. A method of laying pipelines underground as claimed in claim 1, wherein said pilot head has a propelling function, and said method comprises a first step wherein the pilot jack of the pilot head is propelled in the earth so as to effect earth consolidation while the direction of propulsion of the pilot jack is controlled, a second step wherein a pipeline to be laid is propelled or pushed in the earth by the stroke of propulsion of said pilot head by means of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   143 is the hose 122 which extends into the pipeline 121 to be laid underground following the excavating head and which is connected to a fluid supply source by way of the connector 123 so as to drive the excavating head. The propelling jack 3 is adapted to be operated depending on the amount of excavation made by excavating head 143 so that the guide pipeline 2, the screw conveyor 144 and the excavating head 143 may be recovered in the receiving pit 5.

   The propelling jack 3 completes its propulsion when the leading end of the pipeline 2 to be laid underground reaches inside the receiving pit 5. The screw conveyor 144 has a length nearly equal to that of the guide pipeline, and its intermediate connections can be attached and detached easily by means of couplers.

   Figure 22 shows the internal structure of excavating head 143. The excavating head comprises a casing 146 adapted to be divided into a plurality of sections, a hydraulic motor 149 mounted within the casing and being adapted to be driven by fluid under pressure supplied by hose 147 and discharged through hose 148, said hydraulic motor having an output shaft 150 which is engaged with a coupling 151, a conveyor or driving shaft 152 which is engaged with the coupling and is adapted to directly transmit the rotation of hydraulic motor 149 to screw conveyor 153. The coupling 151 has a gear

   154 fitted thereto which is engaged with a gear 155. The gear 155 is adapted to drive through a shaft 156 having fixedly secured thereto a gear 157. The gear 157 is engaged in turn with ring gear 158. The ring gear 158 is coupled with a cutter driving shaft 159.The cutter means 161 is adapted to be rotated in the direction reverse to the directtion of rotation of the screw conveyor through a cylindrical bearing and a thrust bearing mounted between the casing 146 and housing 160.

   The housing 160 is fixedly secured to partition 162 which carries the conveyor shaft 152 rotatably. Further, the excavating head 143 has at its front end a guide tube 163 for connecting thereto the guide pipeline 2. The guide tube 163 has an inlet port 164 through which the earth and sand excavated by cutter 161 is directed towards the screw conveyor 153 and the guide pipeline connecting portion 165.

   Connected to the front of the thus constructed excavating head 143 are the guide pipeline 2, and the screw conveyor 144 accommodated within the latter, and also connected to the rear of the excavating head 143 and the pipeline 121 to be laid underground. Using the guide pipeline 2 as a guide, the propelling jack 3 is propelled in response to the progress of excavation of the excavating head 143 so as to lay the pipeline 121 underground.

   Figure 23 shows the detailed structure of a cutter means 161. The cutter means 161 is connected to the cutter driving shaft 159 by means of a bracket 167. The cutter means 161 is of a trapezoidal shape in side elevation and has an inclined surface to which are fitted a plurality of cutter blades 166.

   The earth and sand excavated by the rotation of the cutter means 161 drops through the inlet port 164 into the conveyor chamber 168 and is then sent by the screw conveyor 153 into leading pipeline 2.

   Figure 25 shows a further example having an enlarged earth and sand accommodating chamber 171 in the cutter means 161 so as to make the inlet port 164 of the guide tube 163 larger and also having a scraper 170 mounted in the outer periphery of the inlet port so as to ensure efficient feeding of the excavated earth and sand into conveyor chamber 168.

   Figure 26 shows a section taken along XXVI-XXVI in Figure 25 for the purpose of explaining the relationship between the scraper 170 and the inlet port 164 for excavated earth and sand.

   The excavating head described herein with reference to Figs. 21 to 26 is described and claimed in our divisional application No. 79 26611 Serial No. 1 572 253.

   WHAT WE CLAIM IS: 1. A method of laying pipelines underground, comprising the steps of: (a) providing a launching pit and a receiving pit spaced a predetermined distance from the launching pit, (b) installing a pipe propelling device having a propelling jack in the launching pit, (c) propelling a pilot head in the earth by means of the propelling jack of said pipe propelling device, (d) allowing a hose and a cable for driving the pilot head to pass through the inside of a first pipeline to be laid underground.which is led by said pilot head, and pushing and propelling said pipeline in turn in the earth by means of the propelling jack while controlling the direction of propulsion of said pilot head and (e) recovering said pilot head in the receiving pit thereby completing the laying of the pipeline underground.
2. 2. A method of laying pipelines underground as claimed in claim 1, wherein said pilot head has a propelling function, and said method comprises a first step wherein the pilot jack of the pilot head is propelled in the earth so as to effect earth consolidation while the direction of propulsion of the pilot jack is controlled, a second step wherein a pipeline to be laid is propelled or pushed in the earth by the stroke of propulsion of said pilot head by means of

   the propelling jack located in the launching pit, and effecting double-acting earth consolidation by carrying out said first and second steps alternatively and repeatedly so that the pipeline may be laid underground with small propulsion resistance.
3. 3. A method of laying pipelines underground as claimed in claim 1, wherein said pilot head has an excavating function, and said method comprises further the step of propelling the pipeline in the earth by operating the propelling jack installed in the launching pit in synchronism with the progress of excavation while controlling the direction of excavation of the pilot head.
4. 4. A method of laying pipelines underground as claimed in claim 1, wherein said pilot head has an excavating function to be effected by a cutter adapted to be driven by a mud motor, the driving power source of said mud motor being fluid under pressure, said fluid under pressure being supplied as a jet to the excavating surface of said cutter to make the excavated earth and sand into sludge, the arrangement being such that the excavated earth and sand in the form of sludge is discharged from a sludge recovery passage formed in the pilot head to the outside through the pipeline which is connected to the pilot head and which is being laid underground.
5. 5. A method of laying pipelines underground as claimed in claim 1, wherein said method comprises the steps of connecting the pilot head and the pipeline that follows it and is to be laid underground, and pulling back said propelling jack more or less towards the launching pit when the resistance of propulsion of the propelling jack exceeds a predetermined value upon propulsion of the pipeline in the earth, and then propelling the pipeline again in the earth while following and controlling the direction of propulsion of the pilot head.
6. 6. A method of laying pipelines underground, as claimed in claim 1, further comprising the steps of (f) using said first pipeline laid underground as a guide or pilot pipeline and pushing and propelling one-stage or multistage earth consolidating head that follow the guide pipeline by means of the propelling jack; (g) allowing a hose for supplying fluid under pressure to be used for driving the earth consolidating head to pass through the inside of a second pipeline led by said earth consolidating head and to be laid underground; (h) propelling the second pipeline in the earth by the stroke of propulsion of said earth consolidating head by means of the propelling jack and effecting double-acting propulsion repeatedly; and (i) recovering said earth consolidating head in the receiving pit.
7. 7. A method of laying pipelines underground as claimed in claim 1, further comprising the steps of (f) using said first pipeline laid underground as a guide or pilot pipeline and connecting an excavating head following said first pipeline with any earth conveyor means accommodated in the latter, (g) driving and propelling said excavating head in the earth, (h) driving the propelling jack in synchronism with the advancement of the excavating head adapted to be driven by pressurized fluid supplied through a hose laid in the second pipeline to be laid underground following said excavating head, (i) discharging the excavated earth in the receiving pit by means of an earth conveyor means accommodated in the first pipeline already laid underground, and Q) recovering said first pipeline, the earth conveyor means and the excavating head thereby completing the laying of the pipeline of a larger diameter underground.
8. 8. A method of laying pipeline underground as claimed in claim 1, wherein the connection of the pilot head with the pipeline that follow and that is to be laid underground is made by connecting lugs on both ends of the latter by means of bolts and nuts, and an elastic or flexible tube is inserted between the lugs to make loose connections.
9. 9. A method of laying pipelines underground, substantially as herein described with reference to the accompanying drawings.