Prefabricated segment for a tunnel lining with improved joining elements

Abstract

A prefabricated segment (1) of a tunnel lining, having an intrados face (11), an extrados face (12) opposed to the intrados face (11) and a peripheral wall (13) which connects the intrados face (11) and the extrados face (12), comprises at least one male joining element (100) which is intended to cooperate with a respective female joining element of an adjacent prefabricated segment in the tunnel lining. The male joining element (100) comprises : a covering (101) which delimits a chamber (102) and which has a front wall (101a), wherein the covering (101) is embedded in the segment (1) so as to expose the front wall (101a) in the region of the peripheral wall (13) of the segment (1); an engaging pin (105) for engaging the female joining element, wherein the engaging pin (105) is slidingly mounted in the chamber (102) and is movable between a retracted position, in which the engaging pin (105) is completely received in the chamber (102), and an extracted position, in which the engaging pin (105) projects from the chamber (102) through an extraction opening (103) which is formed in the front wall (101a); elastic preloading means (106a, 106b) which are arranged inside the chamber (102) and which act on the engaging pin (105) for moving the engaging pin (105) from the retracted position to the extracted position; and removable or retractable locking means (107) for retaining the engaging pin (105) in the retracted position against the action of the elastic preloading means (106a, 106b). The segment (1) further comprises an auxiliary channel (15) which extends between the intrados face (11) and the chamber (102) which is delimited by the covering (101) of the male joining element (100) and the locking means (107) of the male joining element (100) are removable or retractable through the auxiliary channel (15).

Description

[0001] PREFABRICATED SEGMENT FOR A TUNNEL LINING WITH IMPROVED JOINING ELEMENTS

[0002] DESCRIPTION

[0003] The present invention involves the technical field of constructing natural tunnels and particularly the construction of lining structures for natural tunnels by means of prefabricated segments . More particularly, the invention relates to a prefabricated segment which is provided with improved j oining elements for connecting the segment itsel f to prefabricated segments which are adj acent in a tunnel lining .

[0004] As known, one of the fundamental operations in constructing natural tunnels by underground excavation is the generation of one or more lining layers for stabili zing and containing the walls which are exposed by the excavation .

[0005] One known type of lining for natural tunnels is constituted by prefabricated elements which are made from concrete and which are suitably shaped and mutually j uxtapositioned and known by the term " segments" . This type of lining is typically constructed by sequentially generating, gradually as the excavation advances , lining rings which extend over the entire perimeter of the excavation section, each one formed by a plurality of these segments .

[0006] This type of lining is normally used in natural tunnels which are constructed by means of so-called "mechani zed" techniques . In this case , the basic operations of underground excavation, removal of the excavated material and lining of the walls of the excavation, are continuously and simultaneously carried out by means of large automated machines , which are suitably configured, so-called TBM ( Tunnel Boring Machines ) . These machines carry out the excavation in an integral and continuous manner and simultaneously provide for the removal of the excavated material from the front of the excavation and the construction of the lining of the tunnel gradually as the excavation front advances . In the case of natural tunnels which are constructed using "mechani zed" techniques , there is normally provided a single lining layer which is particularly formed by prefabricated segments as described above .

[0007] However, lining structures which are formed by prefabricated segments can also be advantageously used in the field of construction of tunnels by means of so-called "conventional" techniques , in which the basic operations mentioned above are carried out discontinuously, largely in succession, and are repeated cyclically until the tunnel is complete . In this case , prefabricated segments are used to construct the definitive lining of the tunnel , as an alternative to conventional construction by means of casting in situ using suitable formworks .

[0008] In all cases , in order to ensure the stability of the lining, the segments which form a tunnel lining are typically interconnected to each other mechanically by means of suitable j oining systems . In particular, each segment is connected to the adj acent segments both in a circumferential direction, that is to say, peripheral direction, of the lining, that is to say, with the adj acent segments belonging to the same ring of segments , and in a longitudinal direction of the lining, that is to say, with the adj acent segments belonging to rings of segments which are immediately adj acent to the ring comprising the segment in question .

[0009] There are known various types of j oining systems for segments and these include a type which is quite widespread and which is constituted by the pin type j oining systems . It relates to male / female mechanical j oining systems , typically press- fit , in which a male j oining element which is present in one segment and which comprises an engaging pin engages with a respective female j oining element which is present in an adj acent segment and which comprises a receiving cavity suitable for receiving, where applicable in an irreversible manner, the pin of the male j oining element . These male and female j oining elements are usually enclosed in the casting of a respective segment during the fabrication thereof and are positioned in the segment so as to have the respective engagement portions - that is to say, the pin of the male j oining element and the opening of the receiving cavity of the female j oining element - exposed in an outward direction in the region of the peripheral wall of the segment . The pin type j oining systems constitute an advantageous solution in terms of operational simplicity, ef ficiency of j oining and ease of integration in the prefabricated segments .

[0010] However, the pin type j oining systems have a disadvantage connected with the presence of the pins of the male j oining elements which proj ect with respect to the perimeter of the segment in which they are enclosed and which can therefore be subj ected to impacts during the handling or the storage of the segment after the fabrication until it is installed in a tunnel . I f , following an impact , the pin of a male j oining element is bent or the j oining element is otherwise damaged, the respective segment becomes unusable and has to be replaced . Naturally, this has negative repercussions on the production costs and the logistics of the construction site and, in the worst cases , i f the damage occurs while the segment is being installed, it can cause highly undesirable slow-downs or even stoppages in the advance of the construction of the tunnel lining . In light of the above, a main obj ect of the present invention is to provide a prefabricated segment for constructing tunnel linings comprising one or more j oining elements , in particular male j oining elements , of a pin type j oining group, wherein the possibility of irreparable damage to those j oining elements , in particular the male j oining elements , as a result of impacts during the handling or the storage of the segment itsel f can be excluded or substantially limited .

[0011] Another obj ect of the present invention is to provide a prefabricated segment of the above-mentioned type which can be connected to adj acent segments in a tunnel lining by means of the above-mentioned j oining elements in a simple, stable and where applicable also irreversible and precise manner .

[0012] Another obj ect of the present invention is to provide a prefabricated segment of the above-mentioned type which can be fabricated in a simple manner and with competitive costs , and which can be used without any limitations in order to generate linings in the context of constructing tunnels both with "mechani zed" techniques and with "conventional" techniques .

[0013] According to the present invention, these obj ects are achieved by means of the prefabricated segments having the features set out in the appended claims 1 and 10 , respectively .

[0014] In particular, in a first aspect thereof , the invention relates to a prefabricated segment of a tunnel lining, having an intrados face , an extrados face opposite to the intrados face and a peripheral wall which connects the intrados face and the extrados face , and comprising at least one male j oining element which is intended to cooperate with a respective female j oining element of an adj acent prefabricated segment in the tunnel lining, wherein the male j oining element comprises :

[0015] - a covering which delimits a chamber and which has a front wall , a rear wall which is longitudinally opposite the front wall and a side wall which connects the front wall and the rear wall to each other, wherein the covering is embedded in the segment so as to expose the front wall in the region of the peripheral wall of the segment ;

[0016] - an engaging pin for engaging the female j oining element , wherein the engaging pin is slidingly mounted in the chamber and is movable between a retracted position, in which the engaging pin is completely received in the chamber, and an extracted position, in which the engaging pin proj ects from the chamber through an extraction opening which is formed in the front wall ; elastic preloading means which are arranged inside the chamber and which act on the engaging pin for moving the engaging pin from the retracted position to the extracted position, and

[0017] - removable or retractable locking means for retaining the engaging pin in the retracted position against the action of the elastic preloading means , and the prefabricated segment further comprises an auxiliary channel which extends between the intrados face and the chamber which is delimited by the covering of the male j oining element and the locking means of the male j oining element are removable or retractable through the auxiliary channel .

[0018] Therefore , the invention provides a prefabricated segment comprising a male j oining element of a pin type j oining group provided with an extractable engaging pin . In the retracted position, the engaging pin is completely received inside the male j oining element and does not proj ect from the surface of the segment . In this condition, therefore , the engaging pin is totally protected with respect to impacts which it could suf fer during the handling of the segment . In the extracted position, however, the engaging pin proj ects from the male j oining element and therefore with respect to the surface of the segment and can engage with a female j oining element in a manner completely similar to what occurs in the known pin type j oining groups for segments in tunnel linings . Advantageously, therefore , the engaging pin can be retained in a retracted position during all the storage phases of the segment and handling thereof for transport and installation, and can be extracted only when the segment is in position in the tunnel lining during the construction phase in order to bring about the engagement with a respective female j oining element of an adj acent segment . Even i f the engaging pin is extracted before the segment is installed, the possibility of irreparable damage thereof as a result of impacts is in any case minimi zed because the engaging pin is not rigidly connected to the male j oining element , that is to say, to the segment , but instead can react elastically to an impact with a temporary retraction .

[0019] The movement of the engaging pin from the retracted position to the extracted position, resulting in an "activation" of the male j oining element , advantageously occurs autonomously as a result of the ef fect of elastic preloading means which are arranged inside the male j oining element following the removal or release of locking means which retain the engaging pin in the retracted position . This operation can be carried out manually by an operator at any desired time before or after the positioning of the segment in a tunnel lining in the construction phase , acting from the intrados face of the segment through an auxiliary channel which is suitably provided in the segment itsel f . I f the extraction of the engaging pin, that is to say, the activation of the male j oining element, occurs when the segment is already positioned in the tunnel lining, the elastic preloading means are also capable of bringing about the complete engagement of the engaging pin with the respective female j oining element of an adj acent segment , without any need to apply additional forces from the exterior .

[0020] The prefabricated segment with the above-mentioned features can therefore be connected to adj acent segments in both a longitudinal direction and a circumferential direction by means of a pin type j oining system in a simple , stable and secure manner in any construction context for a tunnel lining by means of prefabricated segments . Using such a segment may be particularly advantageous for constructing definitive linings in tunnels which are constructed by means of "conventional" techniques , in which it is not possible to use longitudinal thrusting actions of a TBM in the advance phases thereof in order to bring about or complete the engagement between male and female j oining elements between segments in the longitudinal direction .

[0021] This prefabricated segment can further be fabricated in a simple manner by means of the conventional methodologies used for fabricating the prefabricated segments of the prior art .

[0022] The dependent claims 2 to 9 relate to preferred or advantageous aspects of the prefabricated segment described above , the content of which is completely embedded herein by reference . In a second aspect thereof , the invention relates to a prefabricated segment for a tunnel lining, having an intrados face , an extrados face opposite to the intrados face and a peripheral wall which connects the intrados face and the extrados face , and comprising at least one male j oining element which is intended to cooperate with a respective female j oining element of an adj acent prefabricated segment in the tunnel lining, wherein the male j oining element comprises :

[0023] - a covering which delimits a chamber and which has a front wall , a rear wall which is longitudinally opposed to the front wall and a side wall which connects the front wall and the rear wall to each other, wherein the covering is embedded in the segment so as to expose the front wall in the region of the peripheral wall of the segment , and

[0024] - an engaging pin for engaging the female j oining element , wherein the engaging pin is slidingly mounted in the chamber and is movable between a retracted position, in which the engaging pin is completely received in the chamber, and an extracted position, in which the engaging pin proj ects from the chamber through an extraction opening which is formed in the front wall , and wherein the engaging pin comprises a thrusting base which cooperates with the side wall of the lining in an air-tight manner .

[0025] The prefabricated segment further comprises an auxiliary channel which extends between the intrados face and the chamber of the male j oining element and the engaging pin is moved from the retracted position to the extracted position by inj ecting a pressuri zed fluid into the chamber which is delimited by the covering of the male j oining element through the auxiliary channel . This prefabricated segment constitutes an alternative embodiment of the present invention in which the general inventive concepts forming the basis thereof , particularly the presence of at least one male j oining element of a pin type j oining group provided with an extractable engaging pin, are implemented with a di f ferent operation of this male j oining element , affording the same advantages described above in relation to the first aspect of the invention .

[0026] In greater detail , in this case the at least one male j oining element does not have elastic preloading means and the movement of the engaging pin from the retracted position to the extracted position is obtained by means of a pressuri zed fluid which is inj ected into the chamber of the male j oining element through the auxiliary channel which is suitably provided in the segment . In this embodiment of the prefabricated segment according to the invention, therefore , the at least one male j oining element substantially operates as a pneumatic or hydraulic cylinder .

[0027] Additional features and advantages of the invention will become more evident from the following detailed description of preferred embodiments thereof which is given herein below by way of non-limiting example with reference to the appended drawings , in which :

[0028] - Figure 1 is a schematic, perspective view of a preferred embodiment of a prefabricated segment according to the present invention;

[0029] - Figure 2 is a schematic cross-sectional view of the segment of Figure 1 in the region of the central surface of the segment parallel with the intrados face and the extrados face ;

[0030] Figure 3 is a schematic, cross-sectional view of the segment of Figure 1 in the region of the line I I I- I I I of Figure 1 which shows a male j oining element of the segment of Figure 1 in a non-operative condition;

[0031] - Figure 3a is a view similar to the view of Figure 3 which shows the male j oining element in an operative condition;

[0032] Figure 4 is a schematic, cross-sectional view of the segment of Figure 1 in the region of the line IV- IV of Figure 1 , which shows a female j oining element of the segment of Figure 1 ;

[0033] Figure 5 is a schematic, perspective view of two prefabricated segments similar to the segment of Figure 1 , which are adj acent to each other ;

[0034] Figure 6 is a schematic, cross-sectional view of the segments of Figure 5 in the region of the line VI-VI of Figure 5 which shows a male j oining element and a female j oining element of these segments in a close condition, but not yet interconnected;

[0035] - Figure 6a is a view similar to the view of Figure 6 which shows the male j oining element and the female j oining element in a close and interconnected condition;

[0036] - Figures 7 , 7a and 7b are schematic, perspective views which show steps of installing and j oining the segment of Figure 1 in a tunnel lining, and

[0037] - Figures 8 , 8a are schematic cross-sectional views which are similar to the views of Figures 3 , 3a, respectively, but in relation to another preferred embodiment of a prefabricated segment according to the present invention .

[0038] Figure 1 shows a preferred embodiment of a prefabricated segment according to the present invention which is generally designated 1 .

[0039] The segment 1 is intended to be installed in a tunnel lining 10 which is constructed by means of prefabricated segments , wherein the segments are arranged so as to form a plurality of rings which have a closed circular form and which are mutually adj acent in a longitudinal development direction of the tunnel in a manner known per se ( see Figures 7 , 7a, 7b ) .

[0040] The segment 1 is constituted in known manner by a prefabricated element which is made of reinforced concrete and which is configured as a ring segment having a rectangular or trapezoidal peripheral shape ( in the case of the so-called " key segment" and the two segments which are circumferentially adj acent thereto of each ring of the tunnel lining) and a curvature in one of the two extent directions , in particular the greatest extent direction, corresponding to the curvature of the rings which constitute the lining . The segment 1 therefore comprises an intrados face 11 which, in the installed condition of the segment 1 , is directed towards the interior of the tunnel , an extrados face 12 opposite to the intrados face 11 and a peripheral wall 13 which connects the intrados face 11 and the extrados face 12 and which is formed by a pair of long sides or faces 13a which are mutually parallel and by a pair of short sides or faces 13b which are mutually parallel or oblique .

[0041] The segment 1 is provided in a manner known per se with a peripheral fluid-tight seal 14 which extends along the entire peripheral wall 13 , preferably near the extrados face 12 , in order to bring about a sealing in the region of the j oining gaps which are formed between adj acent segments in the tunnel lining 10 .

[0042] Still in the region of the peripheral wall 13 , the segment 1 comprises at least one male j oining element 100 of a pin type j oining group which is intended to cooperate with a respective female j oining element which is provided in a segment adj acent to the segment 1 in the tunnel lining 10 . Preferably, the segment 1 itself also comprises at least one female joining element 200 which is intended to cooperate with a respective male joining element which is provided in an additional segment adjacent to the segment 1 in the tunnel lining 10. The at least one female joining element 200 is preferably arranged at a side of the peripheral wall 13 opposed to the side, at which the at least one male joining element 100 is arranged.

[0043] The segment 1 may advantageously comprise a plurality of male joining elements 100 and a plurality of female joining element 200 which are intended to cooperate with corresponding female joining elements or male joining elements, respectively, which are arranged in segments adjacent to the segment 1 in the tunnel lining 10, wherein each pair of male and female joining elements forms a pin type joining group.

[0044] As can better be seen in Figure 2, in the preferred embodiment considered here, the segment 1 comprises three male joining elements 100, 100A, 100B which are mutually identical and three female joining elements 200, 200A, 200B which are mutually identical. Two of the male joining elements, in this instance the elements 100 and 100A, are arranged in the region of one of the long sides 13a of the peripheral wall 13, while a third male joining element, in this instance the element 100B, is arranged in the region of one of the short sides 13b of the peripheral wall 13. Similarly, two of the female joining elements, in this instance the elements 200A and 200B, are arranged in the region of the other long side 13a of the peripheral wall 13 while a third female joining element, in this instance the element 200, is arranged in the region of the other short side 13b of the peripheral wall 13 . The male and female j oining elements which are located in the region of opposite sides of the pairs of sides 13a or 13b are preferably arranged so as to form in pairs j oining elements which are axially aligned in the longitudinal extent direction thereof .

[0045] Figures 3 and 3a show in greater detail one of the male j oining elements of the segment 1 , in this instance the male j oining element 100 , in two di f ferent conditions which this element can take up, that is to say, a non-operative condition, also indicated below as the "armed condition" of the male j oining element 100 , and an operative condition, also indicated below as the "activated condition" of the male j oining element 100 . The following description also applies to the other male j oining elements 100A and 100B of the segment 1 which, as mentioned, are preferably identical to the male j oining element 100 . The male j oining element 100 comprises a covering 101 which delimits a chamber 102 having a uni form cross-section which is preferably circular and a longitudinal axis Xl-Xl .

[0046] The covering 101 comprises a front wall 101a, a rear wall 101b which is longitudinally opposed to the front wall 101a and a side wall 101c which connects the front wall 101a and the rear wall 101b to each other . The front wall 101a and the side wall 101c are preferably constructed in one piece while the rear wall 101b is preferably constructed as a separate piece which can be fixed in a removable manner, for example , by means of screws , to the side wall 101c . The covering 101 is embedded in the casting of concrete during the fabrication of the segment 1 in such a manner that the front wall 101a which is intended to be connected to a respective female j oining element of a segment which is adj acent to the segment 1 is exposed towards the exterior of the segment 1 in the region of the peripheral wall 13 thereof .

[0047] The front wall 101a of the covering 101 is provided with an extraction through-opening or through-hole 103 which is coaxial with respect to the axis Xl-Xl which allows an extractable engaging pin of the male j oining element 100 , which is described in greater detail below, to be extracted . Externally, the front wall 101a is preferably delimited by a planar surface , which is arranged substantially in alignment and flush with the peripheral wall 13 of the segment 1 , and is preferably provided with a centring proj ection 104 which is intended to cooperate with a centring cavity with a conj ugate shape with respect to a respective female j oining element of a segment adj acent to the segment 1 . The centring proj ection 104 is preferably arranged concentrically relative to the extraction opening 103 and preferably has a tapered shape , more preferably a f rustoconical shape .

[0048] The centring proj ection 104 is provided in the male j oining elements of all the segments 1 of a tunnel lining with the exception of the key segment and the pair of segments which are circumferentially adj acent thereto in each covering ring . In this case , in fact , the presence of the centring proj ections 104 would impede the final positioning - which can occur simply by means of a radial insertion movement - of the key segment . In the case of the segments which are circumferentially adj acent to the key segment , the absence of the centring proj ection 104 can be limited to the male j oining elements which are positioned in the region of the short sides 13b of the respective peripheral walls which are intended to face the key segment . The male j oining element 100 further comprises an engaging pin 105 which can be extracted from the chamber 102 . The engaging pin 105 is substantially constituted by a rod 105a which is provided at one end with a thrusting base 105b . The rod 105a has a cross-section which is preferably circular, with a diameter dl . The thrusting base 105b also has a crosssection which is preferably circular with a diameter D greater than dl and substantially identical to the internal diameter of the chamber 102 .

[0049] The engaging pin 105 is slidingly mounted coaxially with the interior of the chamber 102 and is movable , in particular linearly translatable , with respect thereto between a retracted position - shown in Figure 3 and corresponding to the armed condition of the male j oining element 100 - in which the engaging pin 105 is completely received in the chamber 102 and therefore does not proj ect from the peripheral wall 13 of the segment 1 and an extracted position - shown in Figure 3a and corresponding to the activated condition of the male j oining element 100 - in which the engaging pin 105 proj ects with its own rod 105a from the chamber 102 and therefore with respect to the peripheral wall 13 of the segment 1 through the extraction opening 103 which is provided in the front wall 101a of the covering 101 .

[0050] The movement of the engaging pin 105 from the retracted position to the extracted position is brought about by means of the action of elastic preloading means which are arranged inside the chamber 102 . The elastic preloading means can advantageously comprise one or more compression springs which are operatively interposed between the rear wall 101b of the covering 101 and the thrusting base 105b of the engaging pin 105 . In particular, in the preferred embodiment illustrated here , the elastic preloading means are constituted by a pair of nested compression springs 106a, 106b .

[0051] In the armed condition of the male j oining element 100 , the compression springs 106a, 106b are located in a compressed condition and preload the engaging pin 105 in the direction of the extracted position thereof . In order to indefinitely maintain this condition without intervention from the exterior, the male j oining element 100 comprises removable or retractable locking means which are suitable for cooperating with the engaging pin 105 in the retracted position thereof in order to retain it in this position, acting against the action of the compression springs 106a, 106b or generally the elastic preloading means .

[0052] According to a preferred embodiment which is shown in the Figures , the locking means comprise a removable locking bar 107 having a first end which engages with the engaging pin 105 and a second end in the region of the intrados face 11 of the segment 1 . Preferably, the locking bar 107 has dimensions and is configured so that the second end thereof is located flush with the intrados face 11 in order not to obstruct the handling and / or storage of the segment 1 . I f , in the examples shown in the Figures , the second end of the locking bar 107 is provided with a gripping portion, for example , in the form of an eyelet or eyebolt , which proj ects substantially with respect to the intrados face 11 , this gripping portion is advantageously connected to the locking bar 107 in a removable manner and is applied to the second end of the locking bar 107 only when the bar has to be removed, that is to say, extracted .

[0053] The locking bar 107 is removably inserted into an auxiliary channel 15 which is suitably provided in the segment 1 , extending between the intrados face 11 thereof and the chamber 102 of the male j oining element 100 . More speci fically, the auxiliary channel 15 is connected to a corresponding opening or hole 108 which is formed in the side wall 101c of the covering 101 of the male j oining element 100 .

[0054] The auxiliary channel 15 can be advantageously constructed during the casting of the segment 1 , embedding therein the male j oining element 100 in the armed condition - and therefore with the locking bar 107 inserted in the chamber 102 and engaged with the engaging pin 105 - and using the locking bar 107 itsel f , where applicable in a state surrounded by a sheath, as the removable reinforcing element .

[0055] According to an alternative preferred embodiment , which is not shown in the Figures , the locking means could comprise a threaded pin or a screw which is received in the hole 108 , in this case correspondingly provided with a thread which is formed in the side wall 101c of the covering 101 of the male j oining element 100 . In a screwed condition, the threaded pin or screw proj ects inside the chamber 102 so as to cooperate with the engaging pin 105 and to retain it in the retracted position while , in an unscrewed condition, the threaded pin does not proj ect inside the chamber 102 and releases the engaging pin 105 . In this case , the actuation, particularly the unscrewing and the resultant retraction of the threaded pin or screw, can also be carried out through the auxiliary channel 15 which is provided in the segment 1 by means of a suitable rod-like tool which can be inserted in this auxiliary channel 15 .

[0056] In all cases , when the locking means are removed or retracted in order to activate the male j oining element 100 , the engaging pin 105 is no longer retained in the retracted position and the action of the elastic preloading means , in particular here of the compression springs 106a, 106b, autonomously brings about the extraction thereof from the chamber 102 and where applicable the simultaneous engagement with a respective female j oining element of an adj acent segment i f the activation is brought about when the segment 1 is already positioned in a tunnel lining . In the activated condition of the male j oining element 100 , the compression springs 106a, 106b take up an expanded condition and maintain the engaging pin 105 in the extracted condition with the thrusting base 105b thereof in abutment against the front wall 101a of the covering 100 .

[0057] Figure 4 shows in greater detail one of the female j oining elements of the segment 1 , in this instance the female j oining element 200 . The following description also applies to the other female j oining elements 200A and 200B of the segment 1 because they are preferably identical to the female j oining element 200 .

[0058] The female j oining element 200 is configured to receive and preferably block in an irreversible manner the engaging pin 105 of a respective male j oining element which is present in a segment adj acent to the segment 1 .

[0059] In greater detail , the female j oining element 200 comprises a covering 201 which delimits a chamber 202 having a longitudinal axis X2-X2 .

[0060] The covering 201 comprises a front wall 201a, a rear wall 201b which is longitudinally opposed to the front wall 201a and a side wall 201c which connects the front wall 201a and the rear wall 201b to each other . The front wall 201a and the side wall 201c are preferably constructed in one piece while the rear wall 201b is preferably constructed as a separate piece which can be fixed in a removable manner, for example , by means of screws , to the side wall 201c . The covering 201 is embedded in the concrete casting during the fabrication of the segment 1 in such a manner that the front wall 201a which is intended to be connected to a respective male j oining element of a segment adj acent to the segment 1 is exposed in an outward direction of the segment 1 in the region of the peripheral wall 13 thereof .

[0061] The front wall 201a of the covering 201 is provided with an insertion through-opening or through-hole 203 , which is coaxial with respect to the axis X2-X2 and which allows the insertion of the engaging pin 105 of a respective male j oining element of a segment adj acent to the segment 1 . Externally, the front wall 201a is preferably delimited by a planar surface , which is arranged substantially in alignment and flush with the peripheral wall 13 of the segment 1 , and is preferably provided with a centring cavity 204 which is intended to cooperate with the centring proj ection 104 with a shape which is conj ugate with respect to the male j oining element . Similarly to this centring proj ection 104 , the centring cavity 204 is preferably arranged concentrically with respect to the insertion opening 203 and preferably has a tapered shape , more preferably a f rustoconical shape .

[0062] In the chamber 202 , at least in a zone proximal to the front wall 201a, there is defined a f rustoconical blocking seat 205 which extends coaxially with respect to the insertion opening 203 and which tapers in the direction towards it .

[0063] There is arranged in the blocking seat 205 a blocking sleeve 206 which is configured to receive internally the rod 105a of the engaging pin 105 of a male j oining element and in order to cooperate externally in abutment with the blocking seat 205 itsel f . In greater detail , the blocking sleeve 206 has internally a shape which is conj ugate with respect to the shape of the rod 105a, and transverse dimensions which slightly interfere with the rod 105a, therefore preferably a cylindrical shape with a diameter d2 which is slightly less than the diameter dl . Externally, the blocking sleeve 206 has a f rustoconical shape which is substantially conj ugate with respect to the shape of the blocking seat 205 .

[0064] In order to allow the insertion of the rod 105a of the engaging pin 105 of a male j oining element , the blocking sleeve 206 has a configuration which is at least partially elastically flexible in a radial direction . In greater detail , the blocking sleeve 206 preferably comprises a plurality of blocking fingers 206a which extend longitudinally and which have longitudinally a tapered shape or wedge-like shape . The blocking sleeve 206 which is configured in this manner can be constructed in one piece , generating a plurality of longitudinal notches along a section with a suitable length of the wall thereof so as to form the plurality of blocking fingers 206a or can be formed by a plurality of separate blocking fingers 206a which are arranged circumferentially adj acent and preferably maintained mutually in position by means of one or more annular connection elements .

[0065] The blocking sleeve 206 is received in the blocking seat 205 in a freely translatable in the longitudinal direction and is maintained in position in the blocking seat 205 , in particular laterally in abutment against the f rustoconical wall of the blocking seat 205 , by means of the action of elastic preloading means which are arranged inside the chamber 202 . The elastic preloading means may advantageously comprise one or more compression springs which are operatively interposed between the rear wall 201b of the covering 201 and the blocking sleeve 206 . Particularly in the preferred embodiment illustrated here , the elastic preloading means are constituted by a compression spring 207 .

[0066] Figure 5 shows two prefabricated segments 1 , 2 according to the present invention, which are arranged adj acent to each other . The segments 1 , 2 are identical to each other and all have the features described above . In the segment 1 , the male j oining elements , of which only the elements 100 , 100A are visible here , are already in the activated condition while in the segment 2 the male j oining elements , of which only the element 100 is visible here , are still in the armed condition . The segments 1 , 2 illustrated are by way of example two generic segments of two adj acent rings of the tunnel covering 10 . The segments 1 , 2 are therefore arranged adj acent to each other in the region of two long sides 13a of the respective peripheral walls 13 and are mutually staggered parallel with these sides , that is to say, in the circumferential direction of the tunnel covering 10 . As a result of this staggering, the male j oining element 100 of the segment 2 is coupled with the female j oining element 200A of the segment 1 , as will become more evident in Figures 6 and 6a .

[0067] Figure 6 shows the male j oining element 100 of the segment 2 and the female j oining element 200A of the segment 1 which are in contact with each other with the respective longitudinal axes Xl-Xl and X2-X2 aligned following the pulling together of the segments 1 and 2 , but not yet interconnected in a stable manner because the male j oining element 100 is still in the armed condition, in accordance with the situation depicted in Figure 5 . In greater detail , the male j oining element 100 and the female j oining element 200A are in contact with each other in the region of the centring proj ection 104 and the centring cavity 204 , respectively .

[0068] As may be observed in the Figure , the centring proj ection 104 preferably has a maximum height measured from the planar surface which externally delimits the front wall 101a of the covering 101 of the male j oining element 100 , which is greater than a maximum depth of the centring cavity 204 which is also measured from the planar surface which externally delimits the front wall 201a of the covering 201 of the female j oining element 200A. The di f ference between the maximum height of the centring proj ection 104 and the maximum depth of the centring cavity 204 determines the mutual distance at which the respective j oining elements 100 , 200A abut each other when they are coupled and consequently also the width w of the gap between the sides 13a of the peripheral walls 13 of mutually adj acent segments 1 , 2 .

[0069] Generally, as a result of the cooperation between centring proj ections 104 and centring cavities 204 of pairs of male and female j oining elements of the segments according to the present invention, it is possible to obtain j oining gaps between adj acent segments having a predetermined width w and being substantially more uni form with respect to what can be obtained in the tunnel linings constructed with known segments and j oining systems . This is particularly advantageous for ensuring that the peripheral seals 14 (not shown in Figures 6 and 6a ) of adj acent segments are in contact with each other in the most spatially uni form manner possible and with a degree of compression which is as great as possible for the correct operation thereof . Figure 6a shows the same male and female j oining elements 100 and 200A of Figure 6 which are mutually interconnected following the activation of the male j oining element 100 . The activation of the male j oining element 100 which is obtained by removing the locking bar 107 through the auxiliary channel 15 of the segment 2 , brings about in this case the extraction of the engaging pin 105 and at the same time the insertion thereof in the female j oining element 200A. In greater detail , the rod 105a of the engaging pin 105 is introduced into the chamber 202 of the female j oining element 200A through the insertion opening 203 and forces the passage through the blocking sleeve 206 . As a result of the configuration thereof , described in detail above , it receives the rod 105a by expanding radially and tending at the same time to move longitudinally in translation away from the blocking seat 205 and therefore to compress the compression spring 207 . In a manner known per se , as a result of the combined ef fect of the radial expansion of the blocking sleeve 206 , the thrust applied thereto by the compression spring 207 following the compression thereof and the conical coupling between the external surface of the blocking sleeve 206 and the blocking seat 205 , the rod 105a of the engaging pin 105 is blocked in an irreversible manner, that is to say, without any possibility of retraction, unless by destroying the connection, inside the female j oining element 200 .

[0070] With reference to Figures 7 , 7a, 7b, there is now described a preferred embodiment of a method for installing, more particularly for the mutual j oining, of prefabricated segments having the above-described features in a tunnel lining . These Figures schematically illustrate a portion of a tunnel lining 10 which is formed by prefabricated segments according to the present invention, during construction, wherein the advancing front of the lining 10 which is directed towards the excavation front of the tunnel being constructed, is the one at the left-hand side of the Figures . The lining 10 may equally well constitute the single lining layer with a structural function of a tunnel which is constructed with a mechani zed technique by means of TBM or the lining layer in a used state of a tunnel constructed with conventional techniques .

[0071] In a first step of the method, there is arranged a segment 1 according to the present invention having the features described above ( Figure 7 ) . In the embodiment illustrated in the Figures , the segment 1 has its own male j oining elements 100 , 100A, 100B in the armed condition, that is to say, with the respective engaging pins 105 retracted and retained inside the respective chambers 102 by means of the locking bars 107 . The engaging pins 105 are therefore completely protected with respect to damage which could result from any impacts during the handling of the segment 1 .

[0072] In a subsequent step, the segment 1 is positioned in a predetermined position in the region of the advancing front of the lining 10 , by placing it near segments which are already installed ( Figure 7a ) . In detail , with reference to the example shown in the Figures , the segment 1 once positioned is adj acent in the longitudinal direction to the segments 2 , 3 belonging to the last complete ring of the lining 10 and in the circumferential direction to the segment 4 of the ring in the construction phase . The positioning of the segment 1 leads to a contact between the corresponding pairs of male and female j oining elements which are present in the region of facing sides of the peripheral walls 13 of the segments 1 , 2 , 3 and 4 . In detail , still with reference to the example shown in the Figures , the male j oining elements 100 and 100A of the segment 1 (not visible in Figures 7 , 7a ) are in contact with the female j oining element 200B of the segment 3 and with the female j oining element 200A of the segment 2 , respectively, and the male j oining element 100B of the segment 1 is in contact with the female j oining element 200 of the segment 4 (not visible in Figures 7 , 7a ) . The pairs of male and female j oining elements which are produced as a result of the positioning of the segment 1 in the lining 10 are in a condition corresponding to the one illustrated in Figure 6 and already described in detail above .

[0073] In another subsequent step, the male j oining elements 100 , 100A, 100B of the segment 1 are activated by removing the respective locking bars 107 . The activation of the male j oining elements 100 , 100A, 100B of the segment 1 brings about the extraction of the respective engaging pins 105 and the engagement thereof , which is in particular irreversible , with the corresponding female j oining elements 200B, 200A, 200 of the segments 2 , 3 and 4 which are adj acent to the segment 1 , respectively, as described above with reference to Figure 6a . The segment 1 is also at this point stably interconnected, in particular in an irreversible manner, to the segments 2 , 3 , 4 which are adj acent and the installation thereof is finished .

[0074] The above-described steps are repeated iteratively with additional segments until the lining 10 is complete . According to another preferred embodiment of the installation method for the prefabricated segments according to the present invention, the step of activating the male j oining elements 100 , 100A, 100B of the segment 1 can be carried out before the step of positioning the segment in the respective predetermined position in the lining 10 . The segment 1 is therefore handled for the positioning thereof with the engaging pins 105 of the male j oining elements 100 , 100A, 100B which are already extracted . In this case , however, the engaging pins 105 are also less subj ected to damage from impacts with respect to what occurs in known segments which are provided with pin type j oining systems because , following a potential impact , the engaging pins 105 can yield elastically by partially or fully retracting into the chamber 102 of the respective male j oining element 100 , 100A, 100B .

[0075] In this alternative embodiment , the engagement of the engaging pins 105 of the male j oining elements 100 , 100A, 100B of the segment 1 with the female j oining elements 200B, 200A, 200 of the segments 2 , 3 and 4 which are adj acent to the segment 1 , respectively, is carried out at the same time in the step of positioning the segment 1 in the lining 10 , thanks to the pushing of handling means of the segment 1 .

[0076] Figures 8 , 8a show another preferred embodiment of a prefabricated segment according to the present invention, which is generally referred to by the reference numeral 1 ' .

[0077] Elements of the segment 1 ' which are identical to those of the embodiment of Figures 1 to 6 are provided with the same reference numerals and will not be described again here .

[0078] The segment 1 ' di f fers from the segment 1 described above as a result of the operation of the respective male j oining elements, one of which is shown in detail in Figures 8, 8a and is indicated with the reference numeral 100' . In greater detail, the male joining element 100' does not have any elastic preloading means which act on the engaging pin 105. The movement, in particular the linear translation movement, thereof from the retracted position (Figure 8) to the extracted position (Figure 8a) is obtained in this case by injecting a pressurized fluid 110' inside the chamber 102, upstream of the thrusting base 105b of the engaging pin 105 relative to the extraction direction thereof, through the auxiliary channel 15, which in this case acts as an injection channel. The thrusting base 105b of the engaging pin 105 is provided with at least one sealing ring in order to be able to sealingly cooperate in a fluid-tight manner with the internal surface of the chamber 102, particularly with the internal surface of the side wall 101c of the covering 101 which delimits the chamber 102.

[0079] In this case, the auxiliary channel 15 is preferably provided with a non-return valve 16' in order to retain inside the chamber 102 the pressurized fluid 110' which is injected, thereby allowing the male joining element 100' to autonomously remain in the armed condition before the engagement with a respective female joining element.

[0080] The method for installation, particularly for the mutual joining, of prefabricated segments in a tunnel lining as described above with reference to Figures 7, 7a, 7b can also be carried out using segments 100' alternatively or additionally to segments 100, with the single difference being that in the case of installation of segments 100' the activation step of the respective male joining elements, carried out before or after the positioning of a segment 100' in the lining 10, provides for the injection of a pressurized fluid into the respective chambers 102 through the respective auxiliary channels 15.

Claims

Patent claims1. A prefabricated segment (1) of a tunnel lining (10) , having an intrados face (11) , an extrados face (12) opposite to the intrados face and a peripheral wall (13) which connects the intrados face (11) and the extrados face (12) , wherein the segment (1) comprises at least one male joining element (100, 100A, 100B) adapted to cooperate with a respective female joining element (200, 200A, 200B) of an adjacent prefabricated segment (2, 3, 4) in the tunnel lining (10) , wherein the male joining element (100, 100A, 100B) comprises:- a covering (101) delimiting a chamber (102) and having a front wall (101a) , a rear wall (101b) longitudinally opposed to the front wall (101a) and a side wall (101c) which connects the front wall (101a) and the rear wall (101b) to each other, wherein the covering (101) is embedded in the segment (1) so as to expose the front wall (101a) in the region of the peripheral wall (13) of the segment (1) ; an engaging pin (105) for engaging the female joining element (200, 200A, 200B) , wherein the engaging pin (105) is slidingly mounted in the chamber (102) and is movable between a retracted position, in which the engaging pin (105) is completely received in the chamber (102) , and an extracted position, in which the engaging pin (105) projects from the chamber (102) through an extraction opening (103) which is formed in the front wall (101a) ;- elastic preloading means (106a, 106b) which are arranged inside the chamber (102) and which act on the engaging pin (105) for moving the engaging pin (105) from the retracted position to the extracted position, and- removable or retractable locking means (107) for retaining the engaging pin (105) in the retracted position against the action of the elastic preloading means (106a, 106b) , and wherein the segment (1) comprises an auxiliary channel (15)extending between the intrados face (11) and the chamber (102) which is delimited by the covering (101) of the male joining element (100, 100A, 100B) and the locking means (107) of the male joining element (100, 100A, 100B) are removable or retractable through the auxiliary channel (15) .

2. A prefabricated segment (1) according to claim 1, wherein the locking means (107) comprise a locking bar (107) which is removably inserted in the auxiliary channel (15) and having a first end engaged with the engaging pin (105) in the retracted position and a second end in the region of the intrados face (11) .

3. A prefabricated segment (1) according to any one of the preceding claims, wherein the elastic preloading means (106a, 106b) comprise at least one compression spring (106a, 106b) , preferably at least one pair of nested compression springs (106a, 106b) , which is / are interposed between the rear wall (101b) of the covering (101) of the male joining element (100, 100A, 100B) and a thrusting base (105b) of the engaging pin (105) .

4. A prefabricated segment (1) according to any one of the preceding claims, wherein the front wall (101a) of the covering (101) of the male joining element (100, 100A, 100B) externally comprises a centring projection (104) which is intended to cooperate with a centring cavity (204) with a conjugate shape with respect to the respective female joining element (200, 200A, 200B) of an adjacent prefabricated segment (2, 3, 4) , the centring projection (104) being arranged concentrically relative to the extraction opening (103) and having a tapered shape, preferably a f rustoconical shape .

5. A prefabricated segment (1) according to claim 4, wherein the centring projection (104) has a maximum height greater than a maximum depth of the centring cavity (204) .

6. A prefabricated segment (1) according to any one of the preceding claims, wherein the peripheral wall (13) is formed by two pairs of opposite sides (13a, 13b) , the at least one male joining element (100, 100A, 100B) being arranged in the region of a first side of one of the pairs of opposite sides (13a, 13b) and wherein the prefabricated segment (1) further comprises at least one female joining element (200, 200A, 200B) in the region of a second side, opposed to the first side, of the same pair of opposite sides (13a, 13b) , the female joining element (200, 200A, 200B) being intended to cooperate with a respective male joining element (100, 100A, 100B) of an adjacent prefabricated segment (2, 3, 4) .

7. A prefabricated segment (1) according to claim 6, wherein the female joining element (200, 200A, 200B) is configured to receive and block irreversibly an engaging pin (105) of the respective male joining element (100, 100A, 100B) of an adjacent prefabricated segment (2, 3, 4) .

8. A prefabricated segment (1) according to either claim 6 or claim 7, wherein the female joining element (200, 200A, 200B) comprises :- a covering (201) delimiting a chamber (202) and comprising a front wall (201a) which is provided with an insertion opening (203) for inserting the engaging pin (105) of the respective male joining element (100, 100A, 100B) of an adjacent prefabricated segment (2, 3, 4) , wherein the covering (201) is embedded in the segment (1) so as to expose the front wall (201a) in the region of the peripheral wallchamber (202) , at least in a zone proximal to the front wall (202a) , a f rustoconical blocking seat (205) extending coaxially with respect to the insertion opening (203) and tapering in the direction towards the insertion opening (203) ;- a blocking sleeve (206) which is arranged in the blocking seat (205) , wherein the blocking sleeve (206) is configured to receive internally an engaging pin (105) of the male joining element (100, 100A, 100B) of an adjacent prefabricated segment (2, 3, 4) , and has externally a f rustoconical shape which is substantially conjugate with respect to the shape of the blocking seat (205) , and- elastic preloading means (207) which are arranged inside the chamber (202) and which act on the blocking sleeve (206) in order to urge the blocking sleeve (206) into the blocking seat (205) .

9. A prefabricated segment (1) according to claim 8, wherein the front wall (201a) of the covering (201) of the female joining element (200, 200A, 200B) comprises externally a centring cavity (204) which is intended to cooperate with a centring projection (104) with a shape which is conjugate with respect to the respective male joining element (100, 100A, 100B) of an adjacent prefabricated segment (2, 3, 4) , the centring cavity (204) being arranged concentrically with respect to the insertion opening (203) and having a tapered shape, preferably a f rustoconical shape.

10. A prefabricated segment (1' ) of a tunnel lining (10) , comprising an intrados face (11) , an extrados face (12) opposed to the intrados face (11) and a peripheral wall (13) which connects the intrados face (11) and the extrados face (12) ,wherein the segment (1' ) comprises at least one male joining element (100' ) which is intended to cooperate with a respective female joining element (200, 200A, 200B) of an adjacent prefabricated segment (2, 3, 4) in the tunnel lining (10) , wherein the male joining element (100' ) comprises:- a covering (101) delimiting a chamber (102) and having a front wall (101a) , a rear wall (101b) which is longitudinally opposed to the front wall (101a) and a side wall (101c) which connects the front wall (101a) and the rear wall (101b) to each other, wherein the covering (101) is embedded in the segment (1' ) so as to expose the front wall (101a) in the region of the peripheral wall (13) of the segment (1' ) ; and an engaging pin (105) for engaging the female joining element (200, 200A, 200B) , wherein the engaging pin (105) is slidingly mounted in the chamber (102) and is movable between a retracted position, in which the engaging pin (105) is completely received in the chamber (102) , and an extracted position, in which the engaging pin (105) projects from the chamber (102) through an extraction opening (103) which is formed in the front wall (101a) , and wherein the engaging pin (105) comprises a thrusting base (105b) sealingly cooperating with the side wall (101c) of the covering (101) , wherein the segment (1' ) comprises an auxiliary channel (15) extending between the intrados face (11) and the chamber (102) which is delimited by the covering (101) of the male joining element (101' ) , and wherein the engaging pin (105) is moved from the retracted position to the extracted position by injecting a pressurized fluid (110' ) into the chamber (102) which is delimited by the covering (101) of the male joining element (100' ) through the auxiliary channel (15) .

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