GB2224553A

GB2224553A - Tubular members for forming conduits

Info

Publication number: GB2224553A
Application number: GB8917271A
Authority: GB
Inventors: John Wilfred Thomas Ropkins
Original assignee: AEB Jacked Structures Ltd
Current assignee: AEB Jacked Structures Ltd
Priority date: 1988-07-28
Filing date: 1989-07-28
Publication date: 1990-05-09
Anticipated expiration: 2009-07-28
Also published as: GB8917272D0; GB8818014D0; GB2221972A; GB2224553B; GB8917271D0

Abstract

In a plurality of tubular members (1, 1', 1'', 1''') arranged end to end to form a conduit, at least one of the tubular members (1) has at one end a plurality of projecting portions (2) and at least one other adjacent tubular member (1') has at one end a plurality of recesses (3'). The projecting portions (2) are arranged to mate with the recesses (3') to locate the tubular members (1, 1') relative to each other. Each of the projecting portions (2) and recesses (3') has a pair of bearing surfaces (2a, 2b and 3'a, 3'b), one surface of each pair being arranged to resist movement by a mating tubular member relative to it in one direction around the periphery of its tubular member and the other surface of the pair being arranged to resist such movement in the opposite direction. <IMAGE>

Description

1 - 1 ' IMDrovemencs in and relating to tubular members for

forming_conduits" The invention relates to tubular members for forming conduits.

Tha invention provides a plurality of tubular members arranged end to end to form a conduit, at least one of (n the tubular members having at one end a plurality of projecting portions and at least one other adjacent tubular member having at one end a plurality of reczesses, the projecting portions of the said one tubular member bein-n, arranaed to mate with the recesses of the said CD 0 adjacent tubular member to locate the tubular members rel,aive to each 3t- her, and each of the projecting portions and each of the recesses having a pair of bearing surfaces, one bearing surface of each pair being arranged to resist C) movement by a -mating tubular member relative to it in one C) direction around the periphery of its tubular member, and the other bearing surface of each pair being arranged to 0 resist mivement of a mating tubular mernbar relative to it in the opposite direction.

The said bearing surfaces are advantageously planar and, preferably, the normal to each bearing surface lies in a plane that is parallel to and displaced from the axis of its tubular member.

Advantageously, the projecting pirtions and the recesses are so arranged around the periphery of the 0 tubular members as to tend to resist relative lateral movemant of the tubular members in any direction.

The arrangement of the invention is especially advantageous when the tubular members are being used in a so-called "pipe-jacking" process, in which a conduit is inserted into the ground in a substantially horizontal direction, and, especially, in the method described and claimed in U.K. Patent Specification No. 2 185 277. Such a method may be employed in the construction of tunnels, culverts, underpasses, sub-structures for bridges, and the like, and involves subjecting the tubular members, arranged end to end, to a jacking load in the direction of the axis of the tubular members. In such a method, lateral movement of one tubular member relative to another arising, for example, from -.misalignment of the

C> tubular members should be avoided.

With the arrangeiment of the invention, not only can a joint between adjacent tubular members be provided which has a relatively high, and predictable, resistance to relative lateral movement, but also the entire thickness of the walls of the tubular members can be available for transmitting the jacking load.

Each of the tubular members is advantageously made from reinforced concrete. The tubular members may be each of an internal width of from 900mini to 5m, or more.

The exact arrangement of the projecting portions required in any particular case, including the total area W of the bearing surfaces, the number and the dimensions of the projecting portions, that is to say, the height of each projecting portion from the remainder of tha end surface of the tubular member in the direction of the axis of the tubalar member, the length of each projecting portion at its base in a direction around the periphery of the tubular member, and the angle of inzlination of the bearing surfaces to the axis of the tubular member, will depend on the maximum load in a lateral direction that the tubular members are required to withstand without lateral movement. That arrangement of the projecting portions can be determined taking into account both the strength of the tubular member in compression (that is to say, its resistance to crushing) and its resistance to shear failure through the wall of the tubular member. The same considerations do, of course, apply to the arrangement of the recesses.

The height of each projecting portion from the remainder of the end surface of its tubular member (or the depth of each recess) in the direction 3f the axis of the tubular member is, advantageously, suitably selected from the range of from 25mm to 30Omm for a reinforced concrete tubular member of a width within the range of from 90Omm to 5m.

The angle of inclination of each of the bearing surfaces to the axis of its tubular member is, advantageoisly, within the range of from 00 to 550, 1 - 4 preferably, -sreater than 00 and not exceedii-n 450.

I In the case where the tubular members are used in a pipe-jacking method, as referred to -')ove, and a -::,ckipc, load is applied J_ to the tubular members in the direction of their axis, it is advantageous for the angle of inclination to be as areat as C.D possible, but, taking into account all the e) relevant factors, the angle of inclination is advantageoisly 450 or nearly 450. It may, however, be found that when a jacking load is removed, there is a tendency for the tubular members to move apart in an axial direction than occurs during normal relaxation for example, to differential settle the ground. With an angle of inclin be found that, in such cases, unaccept- to a greater extent of the joints owing ment or movement of ation of 45 0 it may ably large gaps appear between the tubular members. Accordingly, in situations where there is a risk of such movement ocurring and large gaps are unacceptable because, for example, a seal is required, means such as tendons may. be provided for urging the tubular members together on removal of the jacking load. Alternatively, the angle of inclination may be less, for example, from within the range of from 0 0 to 30 0, so that the width of any gap that appears for the same amount of relative axial movement of the tubular members is less.

With tubular members of rectangular cross-section, advantageously, the or each tubular member having projecting portions has four or more projecting portions, one or-more on each side. and its mating tubular member has four or more recesses, one or more on each side.

With tubular members of circular cross-section, it may be found advantageous to provide six or more projecting portions (and six or more recesses) and, preferably, the length of each projecting portion in a direction around the periphery of its tubular member at a position half way up the projecting portion is substantially equal, and also substantially equal to the separation between adjacent projecting portions at the same position. The end of the or each tubular member provided with the projecting portions may then be identical to that provided with the recesses, as the portions between the projecting portions of the one member can provide the recesses of the other.

When the conduit comprises only two tubular members, the end surface of the wall of each tubular member at the opposite end to the projecting portions and recesses, respectively, may be planar, if desired. When three or more tubular members are used to form the conduit, it is advantageous for at least the or each intermediate tubular member to have at one end a plurality of the projecting portions arranged to mate with the recesses of an adjacent tubular member and at its opposite end a plurality of the recesses arranged to mate with the projecting portions of an adjacent tubular member.

Accordingly, the invention also provides a tubular member for forming a conduit with one or more other such tubular members arranged end to end, the tubular member having on one end surface a plurality of projecting portions and on its other end surface a plurality of recesses, the projecting portions being arranged to mate with the recesses of another such adjacent tubular member to locate the tubular members relative to each other, and each of the projecting portions and each of the recesses having a pair of bearing surfaces, one bearing surface of each pair being arranged to resist movement by a mating tubular member relative to it in one direction around the periphery of the tubular member, and the other bearing surface of each pair being arranged to resist movement of a mating tubular member relative to it in the opposite direction.

When the tubular members are to be inserted into the ground in a pipejacking process, the total length of the conduit may be of the order of 10m to 100m. When the tubular members are pre-cast and then transported to the site at which the insertion is to take place then, typically, each tubular member may be of the order of lm in length. A jacking pit, excavated to the desired level, may be made of a size sufficient to allow one tubular member at a time to be lowered into the pit and jacked into the ground. In that case, after each tubular member is lowered into the jacking pit, its projecting portions or recesses are mated with the recesses or projecting portions, respectively, of the immediately preceding tubular member already jacked into the ground, and a jacking load is applied along the axis of the tubular members to insert the conduit formed by the tubular members further into the ground. Alternatively, two or more of the tubular members may b_-- assembled by mating projecting portions with corres ponding recesses to form a conduit before any of them has been inserted, and a jacking load applied to the rear most tubular member to urge the conduit into the ground.

When the tubular members are formed by casting at the site (in situ) then members of a much greater size, for example, of a length of 15m, may be made, and it may only be necessary for two such members to be inserted to provide a conduit of the required length. In that case, it may be preferred for the free end surface of each of the tubular members to be planar. The tubular members may also be inserted in succession or all assembled before insertion, as clescribed above.

Each of the projecting portions and each of the recesses advantageously extends in a direction normal to the axis of its tubular member over at least half, and preferably at least the greater part of, the thickness of the wall of the tubular member. Generally, it is preferred for each of the projecting portions and each of the recesses to extend in a direction normal to the axis of the tubular member across substantially the whole thickness of the wall of the tubular member. In some cases, however, the internal appearance of a conduit formed of such members, where the joints between adjacent tubular members appear stepped around the internal periphery, is undesirable from the aesthetic point of view. Accordingly, each of the projecting portions and each of the recesses may be 3 - 8 arranged to extend from the outer surface of the tubular member towards the inner surface across not the whole but only half or the greater part as referred to above of the thickness of the wall leaving the other, remaining part to forn, a butt joint with its adjacent tubular member. Such an arrangement avoids the stepped appearance of the joints.

In order to form a seal between the tubular members, a sealant material may be introduced between adjacent end surfaces of the tubular members. The sealant material may be in the form of a strip material formed, for example, of a rubber bitumen compound such as that known as "Tok Strip" With such a sealanr material, however, it will L,-sually be found advantageous also to provide means for restraining adjacent tubular members moving apart in an axial direction in order to maintain the seal. Such means may be means such as tendons as referred to above for urging the tubular members together in an axial direction. Alternatively, in the arrangement in which the projecting portions and recesses extend from the outer surface of the tubular member towards the inner surface across only half or the greater part of the thickness of the wall of the tubular member as referred to above, the other portion of the end surface extending over the remaining part of the thickness maybe so arranged as to provide a spigot or socket, so that spigot and socket joints are formed between adjacent tubular members. The end surface of the or each 9 tubular member provided with the projecting portions is advantageously so arranged as to provide the spigot and the end surface of the or each tubular member provided with the recesses so arranged as to provide the socket.

The spigot advantageously extends in the direction of the axis of the tubular member up to approximately one half the height of the projecting portions. In such an arrangement, it may be found advantageous for the angle of inclination of the bearing surfaces to the axis of the tubular member to be approximately 5 0. Each spigot and socket generally has a surface inclined to the axis of the tubular member by only a small angle, for example, of 0 the order of 5 ' and a surface extending substantially normal to the axis. Sealant material introduced between a mating spigot and socket can be trapped in position between the two surfaces inclined only gently to the axis even when the tubular members move apart in a longitudinal direction as, for example, can occur on removal of an axial jacking load or in the case of ground settlement after insertion.

Alternatively, or even in addition, to the above arrangement, at least one of the tubular members may be provided at one end with a sealing member extending around the tubular member and projecting from the end surface of the tubular member in a direction substantially parallel to the axis of the tubular member, and at least one other adjacent tubular member may be provided at one end with a sealing recess extending around the tubular member, the A c- - 10 sealing recess being arranged to accomodate at least a portion of the sealing member. The sealing member is preferably formed from a non- corrosive material, for example, a metal such as stainless steel, copper or aluminium, or a plastics material, and, in the case of a concrete tubular member, is advantageously set in the tubular member when it is cast.

Before the sealing member is inserted into its recess, a plastic sealant material is advantageously introduced into the recess, so that a portion of the sealing member is embedded in the sealant material and a seal is formed. The sealant material is advantageously a non-hardening material, preferably, of such shear strength and capable of such adhesion to the material from which both the sealing member and the tubular member are made, that relative movement of the sealincy member and its recess can take place 0 without the sealant material de-bonding from the sealing member or the recess. The sealant material may be, for example, a petrolatum or rubber bitumen compound, and is preferably capable of being inserted into the sealing recess without the application of heat. With such an arrangement, it is possible for a certain amount of relative longitudinal movement between the tubular members to take place without destroying the seal.

The sealing recess is advantageously of substantially greater dimensions than the sealing member to facilitate insertion of the sealing member in the recess, although such insertion is also facilitated by the mating projecting 4 4 - 11 portions and recesses of adjacent tubular members. Such an arrangement of a sealing member and sealing recess may be used in the arrangement where the projecting portions extend over only half or the greater part of the thickness of the wall of the tubular member, in which case, the sealing member and the sealing recess are advantageously accomodated within the -)ther, rema ning part. The arrangement may, however, also be used where the projecting portions extend across the entire thickness of the wall of the tubular 10 member.

Such a sealing arrangement as described above is described and claimed in our co-pending United Kingdom Patent Application No.37-17272.4'case 11) (a eepf ef- t3t Speeigleaten eg;;hr=14 s a-n:pexp-(4 The invention also provides a method of forming a conduit using a plurality of tubular members constructed in accordance with the invention, and a method of forming such a conduit wherein the tubular members, arranged end to end, are inserted into the ground.

In such a metho.,, a first tubular member may be urged into the ground, a second tubular member then arranged end to end with the first tubular member so that its projecting portions or recesses mate with the recesses or projecting porti,ns, respectively, of the first tubular member, and the second tubular member urged into the ground, the first tubular member being urged further into the ground. One or more successive tubular members may then be inserted into the ground in a - 12 similar manner to the second tubular member until a conduit of the required length is formen the ground. Alternatively, at least first and second tubular members may be arranged end to end before insertion of the first tubular member into the ground, and the said tubular members then inserted into the ground by applying a load to the rearmost tubular member.

Several forms of tubular member constructed in accordance with the invention and suitable for use as one of the tubular members of a plurality of tubular members arranged end to end to form a conduit, and several forms of conduit comprising a plurality of such tubular members arranged end to end and constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a diagrammatic perspective view of one form of tubular member in accordance with the invention; Fig. 2 is a diagrammatic longitudinal section through the axis of a conduit comprising a plurality of - 13 the r-ujular members of Fig. 1; Fig. 3 is a dia7,raminatic perspective view of a GI) second form of tubular ine,,.nbt.-r in acco--dan,e with the in,7e.--itio-.-i; Fig. 4 is a diaDraminatic parspec-tive view of a W C> third fo.:-.n if r-u)ular mam'i-)er in acco.-da--ice with the in-,7ention; Fig. 5 is a diagrammatic longitudinal section through CP C> the axis of a:oi-id--iit coinp--ising a ?lurality of the tubular memOers if Fig. 4; Fig. 6 is a diagrammatic perspective 7iew if a fourth form of tubular member in accordan2e with the invention in co-inbination with anoher such tubilar we,,-nber; Fig. 7 shog, diagrammatically, and on a larger scale, a porcion of a section through the wall of the tub-1lar inembers of Fig. 6 taken along e-he line A-A; Fig. 8 3hows diagrammatically, and Dn a larger scale, a portion ol a section th-ougi the wall of the tubular memiers of Fig. 6 taken alon- -_he line B-B; C) W Fig. 9 is a dia-raminaic perspective vie.g of a fifth C W form of tubular member in a-.eorda--icpwith he in-jention;and Fig. 10 shows diagcanmati,ally, and on a larger scale, 0 a portion if a section through a 3ixth form of tubular member in --om'-,)inatio-i with a--io--htr su:!h tubular member in accordance with the invention.

1 1 Referring to the accompanying drawings, and initially to Fig.1, a tubular member indicated generally by the reference numeral 1 of square cross- section and being of, for example, pre-cast reinforced concrete, has on one end surface la four projecting portions indicated generally by the reference numeral 2, one on each side of the tubular member 1. Each projecting portion 2 extends over the entire thickness of the wall of the tubular member 1 and has a pair of bearing surfaces 2a and 2b, respectively.

The tubular member 1 at its other end lb is formed with corresponding recesses 3 having bearing surfaces 3a and 3b, respectively. Each of the bearing surfaces 2a, 2b and 3a, 3b is planar and is so arranged that its normal lies in a plane that is parallel to, and displaced from, the axis of the tubular member 1.

As shown in Fig. 2, the projecting portions 2 are arranged to mate with recesses 3' (similar to the recesses 3) of a second such adjacent tubular member 1' arranged end to end, and the recesses 3 are arranged to mate with projecting portions 2" (similar to the projecting portions 2) of a third such adjacent tubular member 1", so that the tubular members 1, 1' and 1" are located relative to each other. A conduit of the desired length, for example, for insertion into the ground in a pipe-jacking process as referred to above, can be formed from the requisite number of such tubular members to.-,ether with, if desired, end tubular members 1'" (only one of which is shown) which have planar 1 i end surfaces le at the ends of the conduit.

Each of the bearing surfaces 2a of the tubular member 1 resists movement by the tubular member 1' relative to it in one direction around the periphery of the tubular member 1, and each of the bearing surfaces 2b resists relative movement by the tubular member 1' in the opposite direction. Similarly, each of the bearing surfaces 3a resists movement by the tubular member 1" relative to the tubular member 1 in one direction around the periphery, and each of the bearing surfaces 3b resists relative movement in the opposite direction. With four projecting portions 2, one on eac+ide of the tubular member 1, relative lateral movement in any direction can be prevented. Similar considerations apply to the bearing surfaces of the other tubular members of the conduit.

In Fig. 3, a tubular member indicated generally by the reference numeral 4 of circular cross-section is provided on its end surface 4a with six projecting portions indicated generally by the reference numeral 5, each having a pair of bearing surfaces 5a and 5b, respectively. The projecting portions 5, which are all of equal length in a direction around the circumference of the tubular member are also equally spaced from each other. The two ends of the tubular member 4 are identical, the portions 6 of the end surface 4a between the projecting portions 5 being of suitable dimensions to form recesses at opposite end 4b of the tubular member.

Referring to Fig. 4, a tubular member indicated generally by the reference numeral 7 is similar to the tubular member 1 shown in Fig. 1 except that its project ing portions 8 and its recesses 9 do not extend over the whole thickness of the wall of the tubular member, but only over the greater part of it. For example, the projecting portions 8 and the recesses 9 may extend over two-thirds of the thickness, the remaining one-third, nearest to the inner surface of the tubular member 7 being arranged to form a butt joint with another such adjacent tubular member. When a plurality of such tubular members are assembled to form a conduit as shown in Fig. 5 the stepped appearance of the joints obtained in the ccndu---of Fig. 2 is avoided.

A strip of sealant material may be introduced between adjacent end surfaces of the tubular members of either Fig. 2 or Fig. 5 to form a seal. Tendons can be provided to urge adjacent tubular members together in an axial direction in order to maintain the seal.

Figs. 6 to 8 shown a fourth form of tubular member, indicated generally by the reference numeral 10, in combination with another such tubular member 1T. The tubular members 10 and 10' are similar to the tubular member 7 of Fig. 4 in as much as their projecting portions 11, llI, respectively, on end surfaces 10a and 1Ta, respectively, and recesses (only the recesses12 of the tubular mem-ber 10 are shown) on end surfaces 10b and lTb, respectively, extend over only the greater part of the thickness of the end walls of tne tubular members. They 1 - 17 differ from the tubular member 7 in that the remaining inner part of the end surfaces 10a and 1Wa are formed as spigots 13, 13', respectively, and the remaining inner part of end surfaces 10b and lTb are formed as sockets (only the socket 14 of the tubular member 10 is shown) so that spigot and socket joints are formed between the adjacent tubular members 10 and 10'. Each of the spigots 13, 13' and socket 14 have a surface 13a, 13'a and 14a, respectively, inclined to the axis of the tubular members 10, 10' by a small angle of the order of 5 0, and a surface 13b, 13'b, 14b, respectively, extending substantially normal to the axis. Sealant material 15, which may be of a rubber bitumen compound, for example, that known as "Tok Strip", is located between the spigots and sockets as can be seen in Figs. 7 and 8 where the sealant material 15 is trapped in position between the inclined surfaces 1Ya and 14 even when some relative longitudinal movement between the tubular members 10 and 10' takes place. In such an arrangement, the spigot 13 preferably extends to one half the height of the projecting portions 11 and the projecting portions have an inner face llc which is inclined to the axis of the tubular members by, for example, 5 0. Bearing surfaces lla and llb may also be inclined to the axis at a 0 smaller angle than as shown in Fig. 6, for example, 5 Alternatively to the use of sealant material similar to the sealant material 15, a sealing arrangement as shown in Figs. 9 and 10 can be used when a seal is required.

P.

g Referring to Fig. 9, a pre-cast reinforced concrete tubular member indicated generally by the reference numeral 16 is similar to the tubular member 1 of Fig. 1 except that around its end surface 16a, which has four projecting portions 17 similar to the projecting portions 2, it is provided with a sealing member 18 which extends from the end surface 16a in a direction substantially parallel to the axis of the tubular member. The sealing member 18, which is set in the tubular member 16 when it is cast, is positioned so that it leaves the end surface 16a at a location which is approximately ond third of the distance from the outer surface 16c of the tubular member to its inner surface 16d. The tubular member 16 at its other end surface 16b is formed with recesses 19 similar to the recesses 3 of the tubular member 1, and around the end surface 16b is formed a sealing recess (not shown) containing a soft plastic sealant material (not shown). When the tubular member 16 is arranged end to end with one or more similar tubular members, the projecting portions 17 mate with recesses similar to the recesses 19 on the end surface of an adjacent tubular member and the sealing member 18 enters theSealing recess in the adjacent tubular member, becoming embedded in the plastic sealant material and forming a seal. A similar arrangement can be seen in Fig.

10.

Referring to Fig. 10, two tubular members 20 and 21 are similar to the tubular member 7 of Fig. 4 in that each tubular member is formed with projecting portions 21-2 and mating recesses 23 that extend only over the greater part of the thickness of end walls 20a and 21a, respectively. The tubular member 21 has cast in it a sealing member 24, which extends around its end surface 21a and is positioned so that it leaves the inner portion of the end surface (that is to say, the portion not occupied by the recesses 23). The spaling member 24 extends into a sealing recess 25, which is of considerably greater dimensions than the sealing member 24 to facilitate insertion, and contains 10 a soft plastic sealant material 26 in which the sealing member 24 becomes embedded. The projecting portions 22 and the recesses 23 also facilitate the insertion of the sealing member 24 into the sealing recess 25. The sealing members 18, 24 may be made of a non15 corrosive metal, for example, stainless steel, copper or auluminium, or a plastics material. The sealant material 26 is, preferably, a nonhardening material of low shear strength and capable of good adhesion to both the material from which the sealing 20 member 24 and the tubular members 20, 21 are made so that if relative longitudinal movement between the tubular members 20, 21 takes place, the sealant material 26 shears within itself rather than de-bond from the sealing member 24 or the sealing recess 25. The sealant material may be, 25 for example, a petrolatum or rubber bitumen compound. In use, in a so-called "pipejacking" process, a jacking pit is excavated to the desired level in the ground. The jacking pit is made of a sufficient size to allow one 3 tubular member constructed in accordance with the invention at a time to be lowered into the pit and be jacked into the ground. A first tubular member is lowered and jacked into the ground sufficiently to allow a second tubular member to be lowered into the pit and arranged so that its projecting portions or recesses mate with the corresponding recesses or projecting portions of the first tubular member. A jacking load is then applied along the axis of both the tubular members - the conduit formed bythe first and second tubular 10 so that members is jacked further into the ground. A third tubular member may then be lowered and the process repeated until a conduit of the desired length is inserted into the ground. The jacking load is then removed. The projecting portions and corresponding recesses can prevent relative lateral movement to an extent that can be predicted by their design during the jacking process and after removal of the jacking load due to, for example, ground settlement. The entire thickness of the walls of the tubular members can also be available for transmitting the jacking load. If the sealing arrangement shown in Figs. 6 to 10 are used to provide a seal, some relative longitudinal movement of the tubular members can also be accomodated without destroying the seal.

2-5 An example of suitable dimensions for a tubular member constructed in accordance with the invention is as follows:

The tubular member is of a width of 6m, a height of 3.9m 1 - 21 and a length of lm. The tubular member is provided on one end surface with four projecting portions, one on each side as shown in Fig. 1. Each of the two projecting portions on the vertically-extending sides of 3.9m is of a length at its base of 1.3m and is located in the middle of that side. Similarly, each of the two projecting portions on the horizontally-extending sides of 6m is of a length of 2m at is base and is located in the middle of that side. The height of each of the projecting portions from the remainder of the end surface of the tubular member in an axial direction is of from 150 - 30Omm, and the angle of inclination of the bearing surfaces to the axis of the tubular member is 450.

Although tubular members of rectangular cross-section with one projecting portion on each side and corresponding recesses, and a tubular member of circular cross-section having six projecting portions and corresponding recesses are shown and described above, the tubular members may be provided with more projecting portions and recesses.

For example, a tubular member of rectangular cross-section may be provided with 5 or even 10 projecting portions on each side together with a corresponding number of recesses.

Claims

What we claim is: 1. A plurality of tubular members arranged end to end to

form a conduit, at least one of the tubular members having at one end a plurality of projecting portions and at least one other adjacent tubular member having at one end a plurality of recesses, the projecting portions of the said one tubular member being arranged to mate with the recesses of the said adjacent tubular member to locate the tubular members relative to each other, and each of the projecting portions and each of the recesses having a pair of bearing surfaces, one bearing surface of each pair being arranged to resist movement by a mating tubular member relative to it in one direction around the periphery of its tubular member and the other bearing surface of each pair being arranged to resist movement of a mating tubular member relative to it in the opposite direction.
2. A plurality of tubular members as claimed in claim 1, wherein the bearing surfaces are planar.
3. A plurality of tubular members as claimed in claim 1 or claim 2, wherein the normal to each bearing surface lies in a plane that is parallel to and displaced from the axis of its tubular member.
4. A plurality of tubular members as claimed in any one of claims 1 to 3, wherein the projecting portions and the recesses are so arranged around the periphery of the tubular members as to tend to resist lateral relative movement of the tubular members in any direction.
5. A plurality of tubular members as claimed in any one of claims 1 to 4, which are made from reinforced concrete.
6. A plurality of tubular members as claimed in any one of claims 1 to 5, which are each of an internal width of at least 90Omm.
7. A plurality of tubular members as claimed in claim 5, wherein the height of each projecting portion from the remainder of the end surface of its tubular member in the direction of the axis of the tubular member is within the range of from, 25mm to 30Omm and the width of the tubular member is within the range of from 900l.. 1 to 5m.
8. A plurality of tubular members as claimed in any one of claims 1 to 7, wherein the angle o.L Lnclination of each of the bearing surfaces to the axis of its tubular member is within the range of from 0 0 to 550.
9. A plurality of tubular members as claimed in claim 8, wherein the angle of inclination of each of the bearing surfaces to the axis of its tubular member is greater than 0 0 0 and does not exceed 45
10. A plurality of tubular members as claimed in any one of claims 1 to 9, which are of rectanCular cross-section, and wherein the or each tubular member having projecting portions has four or more projecting portions, one or more on each side, and its mating tubular -nember has four or more recesses, one or more on each side.
11. A plurality of tubular members as claimed in any one of claims 1 to 9, which are of circular cross-section, and wherein the or each tubular member having projecting J - 24 portions has six or more projectinZ portions and its-mating tubular member has six or more recesses.
12. A plurality of tubular members as claimed in any one of claims 1 to 11, which are of circular cross-section, and the length of each projecting portion in a direction around the periphery of its tubular member Pt a position half way lip the projecting portion is substan,iail-, '17,ual, and also sub.stantially equal to t.-,e separation L-et-;een adja--1:nt projecting portions as the same position.
13. A plurality of tubular members as claimed in any one of claims 1 to 12, wherein there arp two tubular members and the end surface of the wall of each tubular member at the opposite end to-the projecting portions and recesses, respectively, is planar.
14. A plurality of tubular members as claimed in any one of claims 1 to 12, wherein there are three or more tubular members, and at- least the or each intermeciate tubular member end has at oneia plurality of the projecting portions arranged C to mate with the recesses of an adjacent tubular member, and at its opposite end a plurality of the recesses arranged to mate with the projecting portions of an adjacent tubular member.
15. A plurality of tubular members as claimed in any one of claims 1 to 14, wherein each of the projecting portions and each of the recesses extends in a direction normal to 1 the axis of its tubular member over at least half of the thickness of the wall of the tubular member.
16. A plurality of tubular members as claimed in claim 15, wherein each of the projecting portions and each of the recesses extends in a direction normal to the axis of its tubular member over at least the greater part of the thickness of the wall of the tubular member.
17. A plurality of tubular members as claimed in any one of claims 15 to 16, wherein each of the projecting portions and each of the recesses extends in a direction normal to the axis of its tubular member across substantially the whole of the thickness of the wall of the tubular member.
18. A plurality of tubular members as claimed in any one of claims 1 to 16, wherein each of the projecting portions and each of the recesses are arranged to extend from the outer surface of the tubular member towards the inner surface across only half or the greater part of the thickness of the wall of the tubular member, the orm other, remaiiiing part being arranged to i a butt joint with an adjacent tubular member.
19. A plurality of tubular members as claimed in any one of claims 1 to 18, wherein a sealant material is introduced between adjacent end surfaces of the tubular members.
20. A plurality of tubular members as claimed in claim 19, wherein the sealant material is in the form of a strip of a rubber bitumen compound.
21. A plurality of tubular members as claimed in claim 19 or claim 20, wherein means for restraining adjacent tubular members moving apart in an axial direction is provided.
22. A plurality of tubular members as claimed in claim 21, wherein the restraining means comprises tendons for urging the tubular members together in an axial direction.
23. A plurality of tubular members as claimed in any one of claims 1 to 17 and 19 to 22, wherein each of the projecting portions and each of the recesses is arranged to extend from the outer surface of the tubular member towards the inner surface across only hallf or the greater part of the thickness of the wall of the tubular member, the ottier portion of the end surface extending over the remaining part of the thickness being so arranged as to provide a spigot or a socket so that spigot and socket joints are formed between adjacent tubular members.
24. A plurality of tubular members as claimed in claim 23, wherein the end surface of the or each tubular member provided with the projecting portions is so arranged as to provide the spigot, and the end surface of the or each tubular member provided with the recesses is so arranged as to provide the socket.
25. A plurality of tubular members as claimed in claim 24, wherein the spigot extends in the direction of the axis of the tubular member up to approximately one half of the height of the projecting portions.

4 - 27
26. A plurality of tubular members as claimed in any one of claims 23 to 25, wherein the angle of inclination of the bearing surfaces to the axis of its tubular member is 0 approximately 5
27. A plurality of tubular members as claimed in any one of claims 1 to 26, wherein at least one of the tubular members is provided at one end with a sealing member extending around the tubular member and projecting from the end surface of the tubular member in a direction substantially parallel to the axis of the tubular member, and at least one other adjacent tubular member is provided at one end with a sealing recess extending around the tubular member, the sealing recess being arranged to accomodate at least a portion of the sealing member.
28. A plurality of tubular members as claimed in claim 27, wherein the sealing member is formed from a noncorrosive metal.
29. A plurality of tubular members as claimed in claim 28, wherein the sealing member is formed from stainless steel, copper, or aluminium.
30. A plurality of tubular members as claimed in claim 28, wherein the sealing member is formed from a plastics material.
31. A plurality of tubular members as claimed in any one of claims 27 to 30, wherein the tubular member is formed from concrete and the sealing member is set in the tubular member when it is cast.
32. A plurality of tubular members as claimed in any one of claims 27 to 31, wherein a plastic sealant material is J 28 introduced into the sealing recess so that a portion of the sealing member is embedded in the sealant material and a seal is formed.
33. A plurality of tubular members as claimed in claim 32,-wherein the sealant material is of such shear strength and capable of such adhesion to the sealing member and the tubular member that relative movement of the sealing member and its sealing recess can take place without the sealant material de-bonding from the sealing member or the sealing recess.
34. A plurality of tubular members as claimed in claim 32 or claim 33, wherein the sealant material is capable of being inserted into the sealing recess without the application of heat.
35. A plurality of tubular members as claimed in any one of claims 27 to 34, wherein the sealing recess is of substantially greater dimensions than the sealing member to facilitate insertion of the sealing member in the sealing recess.
36. A plurality of tubular members as claimed in any one of claims 27 to 35, wherein each of the projecting portions and each of the recesses are arranged to extend from the outer surface of the tubular member towards the inner surface across only half or the greater part of the thick- ness of the wall of the tubular member, and the sealing member and the sealing recess are accomodated within the remaining part.

1 7 1 C - 29
37. A tubular member for forming a conduit with one or more other such tubular members arranged end to end, the tubular member having on one end surface a plurality of projecting portions and on its other end surface a plurality of recesses, the projecting portions being arranged to mate with the recesses of another such adjacent tubular member to locate the tubular members relative to each other, and each of the projecting portions and each of the recesses having a pair of bearing surfaces, one bearing surface of each pair being arranged to resist movement by a mating tubular member relative to it in one direction around the periphery of the tubular member, and the other bearing surface of each pair being arranged to resist movement of a mating tubular member relative to it in the opposite-direction.
38. A tubular member as claimed in claim 37, and suitable for use as one of the plurality of tubular members claimed in any one of claims 1 to 36.
39. A tubular member substantially as hereinbefore described with reference to, and as shown in, Figs. 1 and 2, or Fig. 3, or Figs. 4 and 5, or Figs. 6, 7 and 8, or Fig. 9, or Fig. 10 of the accompanying drawings.
40. A plurality of tubular members substantially as hereinbefore described with reference to, and as shown in, Figs. 1 and 2, or Fig. 3, or Figs. 4 and 5, or Figs. 6, 7 and 8, or fig. 9, or Fig. 10 of the accompanying drawings.
41. A method of forming a conduit using a plurality of tubular members as claimed in any one of claims 1 to 40.
42. A method as claimed in claim 41, wherein the tubular members arranged end to end are inserted into the ground.
43. A method as claimed in claim 42, wherein a first tubular member is urged into the ground, a second tubular member is then arranged end to end with the first tubular member so that its projecting portions or recesses mate with the recesses or projecting portions, resepctively, of the first tubular member, and the second tubular member is urged into the ground, the first tubular member being urged further into the ground.
44. A method as claimed in claim 43, wherein one or more successive tubular members are inserted into the ground in a similar manner to the second tubular member until a conduit of the required length is formed in the ground.
45. A method as claimed in claim 42, wherein at least first and second tubular members are arranged end to end before insertion of the first tubular member into the ground, and the said tubular members are then inserted into the ground by applying a load to the rearmost tubular member.
46. A method of forming a conduit using a plurality of tubular members substantially as hereinbefore described with reference tC Figs. 1 and 2, or Fig. 3, or Figs. 4 and 5, or Figs. 6, 7 and 8, or Fig. 9, or Fig. 10 of the accompanying drawings.
47. A method of inserting a tubular member into the ground as claimed in any one of claims 1 to 29 of U.K.

t ZZ 31 Patent Specification No. 2 185 277, wherein the tubular member is one or more of the tubular members as claimed in any one of claims 1 to 40 herein.

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