Installation and method for carrying out dynamic resistance tests on protection works for use in the geotechnical sector

Abstract

An installation for carrying out dynamic resistance tests on protection works to be used in the geotechnical sector comprises a ropeway which extends from an upstream zone to a downstream zone. A protection work to be tested is installed in an impact zone near the downstream zone. There is movably provided on the ropeway a launching carriage for accompanying the test block during a free descent motion from a predefined starting position along the development of the ropeway as far as a predetermined release position of the block which is located near the impact zone. The installation further comprises a pulling carriage which is arranged on the ropeway and which is connected to a winch system in order to recover it in an upstream direction. The pulling carriage is provided with a coupling for the launching carriage in order to also pull it in an upstream direction as far as the starting position. A disengaging system is provided to disengage on command the coupling of the pulling carriage with respect to the launching carriage and thereby to release the launching carriage in order to allow its free descent motion so as to accompany the test block.

Description

[0001] INSTALLATION AND METHOD FOR CARRYING OUT DYNAMIC RESISTANCE TESTS ON PROTECTION WORKS FOR USE IN THE GEOTECHNICAL SECTOR

[0002] Field of the invention

[0003] The present invention relates to the field of dynamic resistance tests on protection works for use in the geotechnical engineering sector, such as barriers for rockfalls, avalanches, for containing debris, embankments made of reinforced earth and the like .

[0004] The invention has been developed with particular regard, though in a non-limiting manner, for an installation for carrying out dynamic resistance tests on protection works of the type indicated above, wherein a test block having a specific mass is launched at a predetermined velocity against a protection work to be tested, using a ropeway on which a carriage on which the test block is suspended runs .

[0005] Technological background

[0006] In civil engineering, in particular geotechnical engineering, there are used various protection or containment works against events involving landslips, avalanches, debris transported by water courses and other events of the type . These protection or containment works which will also, in the remainder of the present description, be more simply defined as "barriers" or "protection barriers" have a general interception structure which in some cases is underpinned by support elements and foundations, as in the case of rockfall barriers and the like, or can be constructed by means of embankments made of natural earth or reinforced earth.

[0007] Some solutions make provision for the interception structure to be constructed with one or more metal nets of various types and formations . Other solutions instead provide for theformation of reinforced earth. In any case, the interception structures of the protection works have the main obj ective of supporting the direct impact of the mass of a block, deforming elastically and / or plastically, thereby transmitting the force to the support elements and the foundations when a protection work of the barrier type is involved or by absorbing the impact of the block with deformations of the reinforced earth itself in the entire section thereof .

[0008] The resistance of such protection works to the impacts is tested in suitable test areas where, for example, the barrier to be tested which is arranged in a specific position is subj ected to an impact from a test block which has a predetermined mass and form and which is launched at a predetermined velocity against the barrier . Similarly, the dynamic resistance of an embankment, for example, reinforced earth, is tested. These tests provide data on the mechanical strength and stability of the protection structure being tested on the basis of the kinetic energy which the interception structure, for example, the metal net in the case of barriers, has been able to absorb .

[0009] In order to test the dynamic resistance of the protection works, there are provided test areas in which the above-mentioned test blocks can be allowed to fall vertically onto a protection barrier to be tested, which is installed horizontally. In other cases, the protection barrier or embankment is installed in an erect position and is struck by a test block which is disengaged from a carriage of a ropeway which is allowed to travel with free descent from a starting position upstream of the protection barrier or embankment or more generally the protection work to be tested.The density of the test blocks used, which are typically made from concrete, is typically between 2500 kg / m3and 3000 kg / m3, thus the mass of such test blocks is several tens of tons . Therefore, it is complicated, costly and slow to transport the test block into the starting position of the carriage where the test block then has to be raised onto the carriage using a mechanical lifting arm or equipment which is similarly cumbersome and expensive . These operations further require several specialized operators and are a source of risk to the safety of the operators .

[0010] Statement of invention

[0011] An obj ect of the invention is to solve the problems of the prior art, providing an installation for carrying out dynamic resistance tests on protection works which is economical, safe and simple to use and which requires minimal manpower and specialized workers .

[0012] Another obj ect of the invention is to provide an installation of the above-mentioned type which is flexible in terms of quantity and quality of the tests which can be carried out, also at short intervals of time from each other, and also on protection works of different types, such as, for example, rockfall barriers or embankments made of reinforced earth.

[0013] Another obj ect of the invention is to provide a method for carrying out dynamic resistance tests on protection works which is simple, flexible, convenient, safe and which can ensure a high level of precision of the results and a consistent repeatability over time .

[0014] In order to achieve these obj ects and other obj ects which will become evident from the following description, the invention relates to an installation for carrying out dynamicresistance tests on protection works having the features indicated in the appended claims .

[0015] The invention further relates to a method for carrying out dynamic resistance tests on protection works to be used in the geotechnical field, having the features specified in the appended claims .

[0016] Brief description of the Figures

[0017] Additional features and advantages will become evident from the following detailed description of a preferred embodiment with reference to the appended drawings which are provided by way of non-limiting example and in which:

[0018] - Figure 1 is a schematic front view of an installation for carrying out dynamic resistance tests on protection works, using a ropeway and incorporating features of the present invention;

[0019] - Figure 2 is a perspective view of a launching carriage and a pulling carriage which are engaged with each other and which are used in the ropeway of Figure 1 ;

[0020] - Figure 3 is a perspective view of the launching carriage of Figure 2 ;

[0021] - Figure 4 is a perspective view of the pulling carriage of Figure 2, in which the motor of the lifting winch has been removed for clarity;

[0022] - Figure 5 is a perspective view of a dissipator which is positioned at the downstream end of the ropeway of Figure 1 ; - Figure 6 is a side view of the dissipator of Figure 5;

[0023] - Figures 7 to 12 are front views of the installation of Figure 1 which illustrate successive steps of the dynamic resistance test on a protection work.

[0024] Detailed descriptionNow with reference to Figure 1, an installation 10 for carrying out dynamic resistance tests on protection works to be used in the geotechnical sector comprises a ropeway 11 which is configured to lift a test block 12, also called "polyhedron", having a predetermined mass, to a predetermined height and to launch it against a protection barrier 13 to be tested or against an embankment 19 to be tested, which are positioned in a predetermined impact zone P along the path of the ropeway 11. For reasons of simplicity of description, reference will be made below to the dynamic resistance tests carried out on the protection barrier 13 but the same features and functionalities are also applicable similarly to the dynamic resistance tests which can be carried out on the protection embankment 19.

[0025] By means of the ropeway 11, the test block 12 is transported as far as a desired starting height which is positioned upstream of the impact zone P, determined in such a manner that the test block 12 takes up, when it is launched downstream, a predetermined velocity in the impact zone P so as to supply the impact energy required against the barrier 13 .

[0026] By way of non-limiting example, the installation 10 can be configured and sized to use test blocks 12 having a mass from approximately twenty six to approximately thirty tons which can also reach impact velocities of above 30 m / s . Naturally, the dimensions of the test blocks which can be used in the installation 10 and the impact velocities which they can reach are mainly determined by the standards in the sector and can change in accordance with the dimensions of the ropeway 11 and the difference in height over which it develops starting from an upstream zone M as far as a downstream zone V. By way of non-limiting example, thedifference in height between the upstream zone M and the downstream zone V can be several tens of metres; for example, the ropeway 11 can cover a difference in level of approximately 100 metres over a length of approximately from 200 to 300 metres .

[0027] The ropeway 11 which is shown by way of example in the Figures comprises a pair of carrying ropes 14 which run parallel with each other from the upstream zone M to the downstream zone V. In the example of the ropeway 11 shown in the Figures, the ends of the carrying ropes 14 are anchored at their downstream ends to foundation structures of the generally known type . The ends 14a upstream of the carrying ropes 14 are fixed to the top of a pylon 15 or tower which rises them, for example, by approximately twenty metres from the ground. The pylon 15 is in turn supported by a pair of retaining ropes 16 which are anchored in known manner to a foundation structure in the upstream zone M. The pylon 15 is secured to the ground in a pivotable manner, as indicated by the arrow A in Figure 1, in the upstream and downstream directions . In particular, the pylon 15 is secured to a support base 15a by means of pivot pins 15b which are arranged with the axis thereof transverse with respect to the planes in which the carrying ropes 14 are located. In this manner, the pylon 15 is capable of absorbing the reaction impact on the carrying ropes 14 which occurs at the time of release of the test block 12. Furthermore, the pivoting capacity of the pylon 15 allows the inclination thereof, which, in the example of Figure 1, is approximately 10° in a downstream direction with respect to the vertical, to be adj usted .

[0028] Naturally, the configuration of the ropeway 11 and in particular the support of the carrying ropes 14 or theretaining ropes 16 may vary with respect to the example of the Figures in accordance with the orographic configuration of the installation site and the proj ect specifications of the installation. The carrying ropes 14 which run from the top of the pylon 15 as far as the downstream zone V have a section free from supports and obstacles, along which the test block 12 can advantageously descend with a free descent subj ected to constant acceleration until impact against the barrier 13 or embankment 19 which are positioned in the impact zone P .

[0029] In order to support the test block during the free descent thereof against the protection barrier 13, there is slidingly mounted on the ropeway 11 a launching carriage 22 which is supported by the pair of carrying ropes 14. The test block 12 can be suspended on the launching carriage 22 and can thereby slide in a descending manner guided by the carrying ropes 14 until it is released from the launching carriage 22 just before impact against the barrier 13.

[0030] In order to transport the launching carriage 22 to the desired starting height, there is provided a pulling carriage 24 which is also slidingly mounted on the pair of carrying ropes 14. There is connected to the pulling carriage 24 a pulling rope 17 which is returned, for example, by a winch which is positioned at the top of the pylon 15 and which allows the pulling carriage 24 to be caused to climb again in an upstream direction. The pulling carriage 24 can engage with the launching carriage 22 in order to pull it upstream as far as the desired starting position of the test block 12. A lifting winch 50 on the pulling carriage 24 or alternatively on the launching carriage 22 provides for lifting the test block 12, taking it from any position along the path of the ropeway 11 where it may be located, forexample, from a convenient downstream position, near the impact zone P .

[0031] Downstream of the impact zone P, in which the barrier 13 or the embankment 19 to be tested is erected, there may be provided a safety embankment or earthwork 20 which protects the structures further downstream from the force of the test block 12 if the barrier 13 or embankment 19 should collapse during impact . At the downstream end of the ropeway 11, there is provided a line-end dissipator 18 which brakes and attenuates the travel of the launching carriage 22 after it has released the test block 12 against the barrier 13 or the embankment 19.

[0032] Now with reference to Figure 2, there are illustrated in greater detail the launching carriage 22 and the pulling carriage 24 in the coupled configuration thereof shown in Figure 1. The two carriages 22, 24 can be engaged with each other selectively with an engaging member which is selectively controlled by an actuator . In particular, in the example of the Figures, there is mounted on the pulling carriage 24 a hook 26 which can engage with a transverse bar 28 which is fixed to the launching carriage 22. Naturally, the configuration can be reversed, providing the hook on the launching carriage 22 and the corresponding engaging element on the pulling carriage 24. Naturally, there may also be provided engaging systems of different types from the ones illustrated, for example, of the type with a j aw, bayonet, etc .

[0033] As also illustrated in Figure 3, the launching carriage 22 has a central body 30, at the sides of which there are mounted two support groups 31 which are provided with grooved wheels 32 which support and guide the launching carriage 22on the carrying ropes 14. Each support group 31 also comprises a grooved counter-wheel 32a which maintains the support group 31 slidingly anchored with respect to the carrying rope 14. Each support group 31 is coupled in a pivoting manner by means of a connecting rod 34 to a front guiding group 33 which is also provided with supporting grooved wheels 32, against which there is opposed a counterwheel 32a in order to slidingly anchor the front guiding group 33 to the respective carrying rope 14 which is slightly further downstream with respect to the support group 31. The support group 31 is mounted on the central body 31 via a transverse shaft 35 which allows the movement of the launching carriage 22 to be promoted on the carrying ropes 14 along the path of the ropeway 11. Naturally, the number and arrangement of the grooved wheels 32, 32a as well as the configuration of the support group 31 and the front guiding group 33 can vary with respect to what is illustrated, which is merely a non-limiting exemplary embodiment of the launching carriage 22.

[0034] The launching carriage 22 is the element of the installation 10 which provides for supporting the test block 12 over the travel thereof in a downstream direction and for releasing it slightly before its impact against the barrier 13 or the embankment 19, as provided for by the standards according to which at the time of impact the test block must not be held or secured to anything. To this end, the launching carriage 22 features a suspension device 40 for the test block 12 which supports it until it is selectively unblocked near the barrier 13 in order to release the test block 12. The suspension block 40 is mounted below the main body 31 and comprises a suspension hook 42, on which it is possible to suspend the test block 12 by means of a rope 44 (see Figure 3) . The suspension hook 42 is kept blocked in the positionillustrated in the Figures by a retaining member, such as, for example, a pin (not visible in the Figures) which is secured to a cable 48 (see Figures 10 and 11 ) which has a predetermined length and which is fixed at a location upstream, for example, to the base of the pylon 15. The removal of the retaining member unlocks the suspension device 40, for example, allowing the suspension hook 42 to pivot with the resultant release and liberation of the test block 12 .

[0035] As also illustrated in Figure 4, the pulling carriage 24 also has a central body 43, at the sides of which there are mounted two support groups 44 which are provided with grooved wheels 45 which support and guide the pulling carriage 24 on the carrying ropes 14. Each support group 44 also comprises a grooved counter-wheel (not visible in the Figures) which maintains the support group 44 in a state slidingly anchored to the respective carrying rope 14. Each support group 44 is connected in a pivoting manner by means of a connecting rod 46 to a rear guiding group 47 which is also provided with supporting grooved wheels 45, against which there are opposed a counter-wheel (not visible in the Figures) for slidingly anchoring the rear guiding group 47 to the respective carrying rope 14 which is slightly further upstream with respect to the support group 44. The support group 44 is mounted on the central body 43 via a transverse shaft 48 which allows the movement of the pulling carriage 24 on the carrying ropes 14 along the path of the ropeway 11 to be promoted. Naturally, as described above with reference to the launching carriage 22, in this case too the number and arrangement of the grooved wheels 45 as well as the configuration of the support group 44 and the rear guiding group 47 can vary with respect to what is illustrated, whichis simply a non-limiting exemplary embodiment of the pulling carriage 24 .

[0036] As indicated above, there is mounted on the pulling carriage 24 the lifting winch 50 which is used to raise the test block 12 off the ground. The lifting winch 50 can provide an engaging member, for example, a double hook 52, which is provided to support and lift the test block 12. The lifting winch 50 is provided with pulleys 54 and is actuated by a motor which is protected by a casing 55. The motor can be activated by an operator by means of, for example, a remote control .

[0037] As can better be seen in Figure 4, the hook 26 which allows the pulling carriage 24 to be selectively connected to the launching carriage 22 is actuated by an actuator, preferably a linear actuator 64 which can be selectively controlled remotely by an operator in order to move the hook 26 from an operative engaging position, which is illustrated with a solid line in Figure 4, to an operative disengaged position, which is illustrated with a broken line in the same Figure 4, and vice versa .

[0038] Naturally, the configuration of the carriages 22, 24 can vary with respect to the example of the Figures and is included within the knowledge of the person skilled in the art in the sector who has read the present description understanding the principles of the invention. For example, the launching and pulling functions can be combined in a single carriage which comprises both the lifting members of the test block and the suspension and release members thereof in addition to having the capacity to be pulled upstream by a winch via a pulling rope . The solution described above and illustrated in the Figures is, however, the preferred embodiment because thelaunching carriage 22 is particularly light so that it allows the braking and dissipation of the kinetic energy at the end of travel, downstream, to be carried out more readily by means of the dissipator 18.

[0039] Now with reference to Figures 5 and 6, there is shown the end-of-line dissipator 18 which is positioned at the end of the path of the ropeway 11, in the downstream zone V, near the anchoring to the ground of the pair of carrying ropes 14. In a particular embodiment, the dissipator 18 can be configured to dissipate the kinetic energy of a mass of approximately 1.5 tons moving at approximately 30 m / s in approximately 10 m of effective deceleration space . Naturally, the effective dimensioning of the dissipator depend on the specific configuration of the installation 10 with particular reference to the mass of the launching carriage 22 and the velocity achieved thereby at the end of travel after releasing the test block 12 against the barrier 13 or the embankment 19.

[0040] The dissipator 18 is composed of a group of deformable units which are aligned along the carrying ropes 14. The deformable units of the dissipator 18 can be made of a synthetic material exhibiting plastic deformation with high absorption and limited restitution. In the non-limiting example of the Figures, the deformable units are rings 80 which are made of rubber or another similar material and which are arranged aligned with and near each other with axes which are mutually parallel and transverse with respect to the extent of the carrying ropes 14. The group of rings 80 bears at one end thereof against an abutment 81, preferably supported by support rods 83.The rings 80 are mounted on pairs of opposing wheels 82, by means of which they pass the carrying ropes 14. Each ring 80 is supported by four pairs of wheels 82, two pairs per side, which are arranged so that the rings 80 can be compressed in order to absorb the impact of the launching carriage 22 when it arrives at the travel limit stop along the carrying ropes 14. The pairs of wheels 82, 82' which are adj acent to each other and which are fixed to rings 80 which are also adj acent to each other, respectively, are secured to each other by means of securing plates 84 which are preferably fixed to the four axes of said pairs of adj acent wheels . In this manner, all the rings 80 of the dissipator 18 are secured to each other in a group, with the general capacity for being individually compressed but without losing the mutual connection .

[0041] In a variant which is not illustrated, there may be provided in place of the pairs of wheels 82, 82' guide runners, for example, but in a non-limiting manner, with support surfaces on the carrying ropes 14 which are made of a low-friction material, such as, for example, Teflon® or another material of the type . In this case, it is also possible to provide for the rings 80 of the dissipator, or in any case the deformable units which compose it, to be joined to each other in a group .

[0042] The method for carrying out a dynamic resistance test of a barrier 13 is illustrated with reference to the sequence of Figures 7 to 12 .

[0043] As can be seen in Figure 7, the method provides for a first step in which a test block 12 is lifted off the ground, for example, from a convenient position near the barrier 13. For the lifting operation, the winch 50 on the pulling carriage24 is used. In this step, the launching carriage 22 is engaged with the pulling carriage 24.

[0044] Subsequently, as illustrated in Figure 8, the pulling winch is set up in order to rewind the pulling rope 17 which pulls the pulling carriage 24 and the launching carriage 22 in an upstream direction together with the test block 12 which is supported by the winch 50.

[0045] When the launching carriage 22 has reached the starting position, which in Figure 9 is near the pylon 15, the test block 12 is moved from the pulling carriage 24 to the launching carriage 22 and engaged with the suspension device 40, in particular with the suspension hook 42.

[0046] The launching carriage 22 is then disengaged from the pulling carriage 24, as illustrated in Figure 10, and starts its free descent travel along the path of the ropeway 11, in a downstream direction. The suspension hook 42 with which the test block 12 is engaged is maintained in the locked position by the retaining member which is secured to the cable 48 which is, for example, unwound from a spool which is positioned at the base of the pylon 15. Meanwhile, the pulling carriage 24 remains stopped upstream.

[0047] When the launching carriage 22 is near the barrier 13, as illustrated in Figure 11, the unwinding of the cable 48 stops, pulling the retaining member of the suspension hook 42 with it . The suspension hook 42 thus unlocks, releasing the test block 12 against the barrier 13, during the actual execution of the dynamic resistance test . The test block 12 is then completely disengaged from any element of the launching carriage 22 before striking the barrier 13 in order to carry out the dynamic resistance test thereof .The launching carriage 22 continues its free descent travel until, as can be seen in Figure 12, it is stopped by the dissipator 18 at the travel limit stop . The impact with the dissipator 18 is configured to allow the launching carriage 22 to stop . In fact, when the launching carriage 22 strikes against the deformable units of the dissipator 18, they are deformed in order to absorb the kinetic energy of the launching carriage 22.

[0048] At the end of the test method, the pulling carriage 24 can be brought back in a downstream direction where it can engage with the launching carriage 22 again and position itself to conveniently receive another test block 12.

[0049] Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated without thereby departing from the scope of the present invention .

Claims

Patent claims1. An installation for carrying out dynamic resistance tests on protection works to be used in the geotechnical sector, comprising a ropeway ( 11 ) which extends from an upstream zone (M) to a downstream zone (V) , an impact zone (P) being provided, near the downstream zone along the path of the ropeway, for installing a protection work ( 13, 19) , on which a resistance test has to be carried out by launching against it a test block ( 12 ) with a predetermined mass at a predetermined velocity, on the ropeway ( 11) being movably arranged a launching carriage (22 ) for accompanying the test block ( 12 ) during a free descent motion from a predefined starting position along the development of the ropeway ( 11 ) as far as a predetermined release position of the test block ( 12 ) which is located near the impact zone (P) in such a manner that the test block ( 12 ) which is released by the launching carriage (22 ) strikes the protection work ( 13, 19) at the predetermined velocity, characterized in that the installation ( 10) further comprises a pulling carriage (24 ) which is arranged on the ropeway ( 11 ) and which is connected to a pulling system ( 17 ) in order to recover the pulling carriage (24 ) in an upstream direction, the pulling carriage being provided with a coupling (26) for the launching carriage (22 ) in order to pull it in an upstream direction as far as the starting position, a disengaging system ( 64 ) being provided to disengage on command the coupling of the pulling carriage (24 ) with respect to the launching carriage (22 ) and thereby to release the launching carriage (22 ) in order to allow its free descent motion so as to accompany the test block ( 12 ) towards the impact zone (P) .

2. An installation according to claim 1, wherein the pulling carriage (24 ) comprises winch means (50) for lifting the test block .

3. An installation according to claim 2, wherein the pulling carriage (24 ) comprises motor means for actuating the winch means (50) .

4. An installation according to any one of the preceding claims, wherein the disengaging system of the launching carriage from the pulling carriage is selectively controlled with a remote control .

5. An installation according to any one of the preceding claims, wherein the ropeway is of the type with two carrying ropes and one pulling rope, the pulling rope being connected to the pulling carriage at one end thereof .

6. An installation according to any one of the preceding claims, wherein the ropeway ( 11 ) comprises carrying ropes ( 14 ) which are supported upstream by a pylon ( 15) which is mounted so as to pivot in an upstream direction.. An installation according to any one of the preceding claims, wherein the ropeway ( 11 ) comprises a dissipating member ( 18 ) for dissipating the kinetic energy of the launching carriage (22 ) at the end of the free descent travel thereof, the dissipating member ( 18 ) being arranged downstream of the impact zone (P) .

8. A method for carrying out dynamic resistance tests on protection works to be used in the geotechnical sector by means of an installation ( 10) according to any one of the preceding claims, comprising the steps of :- bringing the pulling carriage (24 ) towards the launching carriage ( 22 ) ;- engaging the pulling carriage with the launching carriage; - loading, from a downstream position, a test block ( 12 ) on the pulling carriage (24 ) or on the launching carriage (22 ) ; - pulling, in an upstream direction, the launching carriage and the pulling carriage with the test block as far as a starting position;disengaging the launching carriage from the pulling carriage so that the launching carriage begins a free descent along the path of the ropeway;- releasing the test block from the launching carriage once it has reached a predetermined release position near the protection work ( 13, 19) to be tested so that the test block strikes the protection work at the predetermined velocity without being secured to the launching carriage (22 ) or the pulling carriage (24 ) .

9. A method according to claim 8, comprising the additional step of braking the launching carriage (22 ) downstream of the impact zone (P) by means of the dissipating member ( 18 ) against which the launching carriage (22 ) will strike at the end of travel .

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