Anchoring device for rods and related system and anchoring method

Abstract

An anchoring device (10) adapted to be used in an anchoring system (100), wherein the device (10) comprises: - a hollow main body (11), which develops along a longitudinal axis (L) between at least a terminal connection part (16) and a terminal interface part (17), and it is configured to be associated to a rod (101) at the connection part (16); - a piston (12) arranged inside the main body (11) and configured to be actuated hydraulically by means of a hydraulic pump (103) to slide inside the main body (11), between a first position (P1) and a second position (P2), - at least an external cylinder (15) arranged at the interface part (17), which develops along the longitudinal axis (L) between a first end portion (27) and a second end portion (28), and configured to deform according to at least two deformation directions.

Description

[0001] ANCHORING DEVICE FOR RODS AND RELATED SYSTEM AND ANCHORING METHOD

[0002] DESCRIPTION

[0003] Field of the invention

[0004] The present invention is placed among the systems adapted to check and improve the load-bearing capability of anchoring rods, which are used to stabilize bulkheads, retaining walls, rock masses and loose soils, or more generally unstable slopes and walls of excavations. In particular, the invention relates a device for anchoring rods, as well as the related anchoring system and method.

[0005] Background of the invention

[0006] Among the defence works for the stabilization of loosely compacted or rocky soils often anchoring systems are implemented capable of transferring the tensions from the unstable areas towards areas having better geomechanical behaviour, which could absorb them and keep the integrity of the whole system-soil.

[0007] The consolidation work to secure an unstable area provides the execution of a drilling and the subsequent insertion in the hole of a rod consisting of bars, tubes or strands, passing through the unstable portion and anchors in the stable portion.

[0008] The process for anchoring the rod in the hole is implemented by means of injection of binding mixtures such as cements or resins, which are performed in the interspace between rod and hole.

[0009] Outside the rod a distribution plate is then positioned which, through a clamping nut, distributes the stresses uniformly between the stable portion and the instable one of the soil.

[0010] The performances of an anchoring system strictly depend upon the tightness of the rod and upon the resistance of the section of the structural element.

[0011] The transfer of forces then triggers a load-bearing resistant mechanism of the anchoring area; therefore, a greater contact surface between the rod and the hole allows a better system performance.

[0012] However, the systems currently in use do not always guarantee an optimum tightness of the anchoring, especially in complex contests such as vertical walls, tunnels or soils with the presence of water, which can hinder fixing the rod in the hole.

[0013] During the implementation of the rods, in fact, it is possible that they involve soils with different consistency and then have a different capability of transferring the loads. With the purpose of checking the effectiveness of the implemented rods, the technical rules provide to perform pulling and testing tests, which are usually performed on a limited number of rods, which rarely exceeds 5% of the total work.

[0014] Therefore, it may happen that some of the implemented rods have a different capability of bearing loads, with respect to those subjected to testing.

[0015] Some of the methods currently widespread in common practice, aimed at geotechnically verifying the soils, at performance improvement testing and at installing the rod in the hole, are analysed hereinafter, by highlighting the critical issues and operational limitations thereof.

[0016] The consistency of the soil is determined with geognostic investigations such as surveys, penetrometric tests, etc. They are specific investigations, which cannot guarantee the homogeneity of the soils subjected to intervention. Local anomalies, such as for example cavities, in fact can only be detected if intercepted by chance.

[0017] The acceptance tests, necessary to verify the correspondence between the design and the completed work, consist in applying, by means of hydraulic jacks, a tensile force on the rod in place and recording the effectiveness of the system. These tests are carried out on a sample basis only on a limited number of implemented rods.

[0018] Both geognostic investigations and acceptance tests are long, complex and expensive procedures and therefore they are performed in minimum number.

[0019] On the contrary, the installation procedures are based on the injection of cement or chemical mixtures, but, when conditions require it, the use of resin cartridges is also provided which, once inserted at the bottom of the hole, are fractured in the insertion phase, they generate a glue which guarantees tightness between the reinforcement and hole walls.

[0020] There are then solutions that use mechanical activation systems to anchor nails or bars in the hole.

[0021] One of these systems uses a bottom-hole expansion shell, with “CT Bolt”-type mechanism, which allows to obtain a tightening through the shell expansion, by applying a tension activated by the rotation of the threaded bar. Such system forces the operator to tighten the bolt by applying rotational forces, imparted at the hole end. This determines an operating difficulty both due to the procedure complexity, and due to the impossibility of using this anchoring method at significant depths. Such limitation is further sharpened when the work is performed on rocky walls, especially when the operators are suspended in roped party.

[0022] A similar anchoring technology is shown in the patent Nr. 0001369710, with title “High efficiency anchor bolt” providing the use of nails which anchor thanks to the radial expansion along the trunk of half-shells made of steel. Even this solution has the limitations described previously, which synthetize in the operating difficulty due to the procedure complexity, to the impossibility of using this anchoring method at significant depths and the installation on rocky walls with operators in roped party.

[0023] Another solution, known as “Swellex” system, uses tubes made of harmonic steel which, folded at one end and provided with connection on the other one, are expanded with high-pressure water until obtaining an optimum adherence in the hole. This system, although effective in rocky contexts, has operating limits in terms of maximum implementable diameter, length and type of reinforcement and moreover it guarantees its effectiveness exclusively in rocky soils. Even for this system the limitations related to installation on rocky walls with operators in roped party are valid. An additional solution is represented by the patent Nr. 102005901284113, with title “Method adapted to allow the increase in capability of the soils to bear loads, characterized in that it provides in one or more points of the reinforcement of stakes, rods or chains a device enabled to drive rostra in the soil therethrough it is possible to inject mortars, consolidating and waterproofing mixtures, etc” which provides a mechanical anchoring by means of rostra which are fixed into the soil after their elongation, also allowing the injection of consolidating or waterproofing mixtures. Such system results to be unsuitable for anchoring in very compact and stone materials, since the rostra do not succeed in penetrating the rocks or highly densely packed soils. This configuration further concentrates the tensions in the contact areas limited by the rostra, by preventing the distribution of the forces in continuous and uniform radial manner, by making it little effective.

[0024] The document WO2017001506 A1 is also known which describes a method for installing an anchoring system. The system comprises a hollow anchor having at least an expandible part and an expansion tool which is inserted, in use, inside the anchor. The expansion tool comprises two expansion elements, identified as hydraulic pistons, whose actuation, constituted by a lateral excursion, brings the expandable part in an expanded condition. The anchoring system also comprises a pump connected to the expansion tool, adapted to put in pressure a hydraulic fluid which actuates the two expansion elements. The expansion of the expandable part is very limited since it is constrained to the size of the two expansion elements, as well as their lateral excursion.

[0025] It is clear that the above-mentioned solutions have some critical issues which make them not adaptable to the different testing operating conditions, geotechnical verification of the soils and anchoring, performance improvement especially in complex situations or in rocked or heterogeneous soils.

[0026] Summary of the invention The technical problem underlying the present invention is then to provide a solution not having the above-mentioned critical issues.

[0027] Such problem is solved by a device according to claim 1 , an anchoring system according to claim 10 and an anchoring method according to claim 12.

[0028] In particular, the present patent introduces a solution capable of improving the performances of the rods, thanks to the increase in the contact surface between the structural element and the soils, by overcoming the limitations of the existing technologies and offering an easy-to-implement method allowing to verify the effectiveness thereof during the installation phase.

[0029] The possibility of verifying homogeneity in the soils in which the rods are inserted is one of the qualities of the following anchoring system, since the installation of the same allows to determine, already during construction, the resistance offered by the soil after an activation of the anchoring itself by means of the device. In this way it will be simple to highlight local geotechnical anomalies and / or the unexpected presence of voids or cavities.

[0030] Moreover, the proposed system and anchoring device at the same time allow to increase the contact surface between soil and structural element of the rod and this involves a significant increase in the performance and allows to implement anchoring systems which do not require binders such as cement grout, resin, etc.

[0031] The anchoring device is adapted to be used in an anchoring system configured to determine the geotechnical resistance of a rod, the mechanical characteristics of soils and / or to improve anchoring performance.

[0032] In particular, the device comprises:

[0033] ■ a hollow main body, which develops along a longitudinal axis between at least a terminal connection part and a terminal interface part and it is configured to be associated to a rod at the connection part;

[0034] ■ a piston configured to be actuated hydraulically by means of a hydraulic pump to slide inside the main body, between a first position and a second position,

[0035] ■ at least an external cylinder arranged at the interface part and configured to deform according to at least a first deformation direction parallel to the longitudinal axis and a second deformation direction transversal to the longitudinal axis, when subjected to a pushing mechanical motion exerted by the piston.

[0036] With the deformation of the external cylinder there is the advantage that it is possible to improve the anchoring and the performance of the rod thanks to the increase in the contact surface between the device connectable to the rod and the soil. The main body, the piston and the external cylinder are mutual coaxial.

[0037] Preferably, the main body has a cylindrical shape and comprises at least a fluid-tight internal chamber, adapted to contain a liquid under pressure for actuating the piston. For example, the liquid is water.

[0038] The internal chamber has a determined extension along the longitudinal axis, which determines the extension of the advance stroke of the piston.

[0039] Preferably, the internal chamber has a vent hole having the function of putting into communication the internal chamber with outside. The vent hole is implemented in a terminal area of the internal chamber, in a position so as to allow the evacuation of the liquid under pressure only when the piston is at the end of the stroke, or when it reaches the second position.

[0040] Preferably interface part of the main body comprises at least:

[0041] ■ an initial portion directed towards the connection part and occupied by the fluid- tight internal chamber,

[0042] ■ a final portion bearing at least two guide slots opposed to each other with respect to the longitudinal axis, wherein the external cylinder surrounds the final portion when it is in a not deformed condition.

[0043] In other words, the external cylinder is associated to the final portion, by surrounding it; such configuration involves that in the not deformed condition of the external cylinder the guide slots are not exposed to view.

[0044] According to an aspect of the present invention, the piston comprises at least a pushing head and it is arranged inside the main body. Moreover, it is specified that an inactive, or resting, condition of the device corresponds to the first position of the piston and that an active, or anchoring, condition of the device corresponds to the second position of the piston.

[0045] According to another aspect of the present invention, the external cylinder is made of steel, or composite material and develops, too, along the longitudinal axis between a first end portion and a second end portion.

[0046] In particular, the external cylinder comprises an expandible central portion equipped with a plurality of deformable flaps connected, at their own opposite ends, respectively to the first end portion and to the second end portion. The flaps are longitudinally separate from each other so that each one thereof is capable of deforming independently from the other one.

[0047] It is to be noted that a not deformed condition of the flaps corresponds to the first position of the piston and that a deformed condition of the flaps corresponds to the second position of the piston.

[0048] Preferably, at least one between the first and the second end portion is configured to move towards the other one as a result of the deformation along the first deformation direction. In other words, in relation to the piston action, one between the first and the second end portion is adapted to be shifted, or moved, towards the other one.

[0049] More preferably, the first end portion is adapted to move towards the second end portion along a direction parallel to the longitudinal axis.

[0050] Moreover, the flaps are configured to deform plastically in radial direction to the main body as a result of the approaching between the first and the second end portion, then along the second deformation direction, going from the not deformed condition, wherein they have rectilinear development, parallel to the longitudinal axis, to the deformed condition, wherein they have an arched shape, or an inverted “V”-like shape with reference to the longitudinal axis.

[0051] Preferably, the external cylinder is provided with an abutment element, or pin, removably associated to the first end portion and arranged transversely to the longitudinal axis. The abutment element is configured to cooperate both with the head of the piston, to be pushed by it during the action of the latter, and with guide slots of the main body, to guide the shifting of the first end portion towards the second end portion during the action of said piston.

[0052] Preferably, the abutment element is inserted removably in two holes obtained in the first end portion.

[0053] Preferably the abutment element comprises a central body on which, in use, the head of the piston abuts and two protruding ends with respect to the body of the external cylinder and suitable to cooperate with the respective guide slots during the piston action.

[0054] Respective means for releasable fixing can be associated to the protruding ends to lock the abutment element to the external cylinder. For example, the protruding ends are equipped with respective holes in which corresponding split pins are inserted, defining the fixing means.

[0055] Such configuration allows to ease the implementation of the device, by easing procedures for maintenance, inspection or replacement of the piston or of the external cylinder.

[0056] According to an embodiment of the present invention, the interface part comprises, additionally, a central portion interposed between the initial portion and the final portion and preferably identical to the latter. In such embodiment, the device comprises two internal chambers and two external cylinders. Specifically, the additional external cylinder surrounds the central portion when it is in a not deformed condition, and the piston is configured to act on each external cylinder bringing both of them in deformation.

[0057] According to another embodiment, the main body comprises an additional connection part and an additional interface part. In such embodiment, the connection part is configured to be connected to a rod at an opposite end with respect to the interface part. Moreover, the additional interface part is interposed between the connection part and the additional connection part, with the respective initial portion directed towards the connection part, and the interface part is connected to the additional connection part, with the respective initial portion directed towards the latter.

[0058] The present invention also relates to an anchoring system configured to determine the geotechnical resistance of a rod, the mechanical characteristics of soils and / or to improve anchoring performance.

[0059] In particular, the anchoring system comprises:

[0060] ■ a rod configured to be inserted in a hole made in a soil to be stabilized;

[0061] ■ an anchoring device as described above, configured to be associated to a lower end of the rod; and

[0062] ■ a hydraulic pump operatively associated at least to the piston and configured to pump liquid under pressure inside the device to actuate the piston, by moving it from the first to the second position.

[0063] Specifically, the hydraulic pump is adapted to introduce the liquid under pressure inside a corresponding internal chamber of the main body of the device.

[0064] Preferably, the anchoring system comprises a manometer operatively associated to the hydraulic pump and configured to detect the liquid pressure inside said device indicating the resistance exerted by the surrounding soil on the flaps in deformation.

[0065] In this way, there is the advantage that without the need for complex systems, from the deformation of the flaps it is possible to obtain, by means of formulations, an estimate of the geotechnical resistance of the rod thereto determined mechanical characteristics of the surrounding soil correspond.

[0066] With one single anchoring system, then, it will be possible to increase the capability in transferring the loads, verifying the homogeneity of the soils subjected to intervention, reducing time and costs for carrying out the works, since as seen the cementation phase is not required.

[0067] The present invention also relates to an anchoring method to determine the geotechnical resistance of a rod, the mechanical characteristics of soils and / or to improve anchoring performance by using an anchoring system as described above.

[0068] In particular, the method comprises at least:

[0069] ■ an insertion phase, wherein an anchoring device as described above is fixed to a lower end of a rod and inserted in a hole made in a soil or in a rock to be stabilized;

[0070] ■ an activation phase, wherein a hydraulic pump starts pumping the liquid under pressure inside the device, by consequently actuating the piston,

[0071] ■ a deformation phase, wherein the piston is progressively pushed by means of the liquid under pressure from the first position to the second position, by causing the expansion of the expandible part and, then, the deformation of the plurality of flaps.

[0072] In the insertion phase, the device is in an inactive condition and the piston present inside thereof is in the first position. On the contrary, in the deformation phase, the passage of the device to an active, or anchoring, condition takes place.

[0073] In the activation phase, preferably, the liquid is introduced in the internal chamber, and in the deformation phase, the liquid under pressure fills-in progressively the internal chamber by making the piston to advance as far as reaching an end of stroke, or the second position. Specifically, when the piston reaches the end of stroke, the liquid under pressure reaches the vent hole implemented in a terminal area of the internal chamber and it is evacuated therethrough into the external environment. This involves the depressurization of the internal chamber.

[0074] Moreover, during the deformation phase, the manometer operatively associated to the hydraulic pump, detects the liquid pressure inside the device, or in the internal chamber, by obtaining a corresponding indication of the resistance exerted by the surrounding soil on the flaps in deformation.

[0075] Other advantages, features and use modes of the present invention will result evident from the following detailed description of some embodiments, shown by way of example and not for limiting purposes.

[0076] Brief description of figures

[0077] The figures of the enclosed drawings will be referred to, wherein:

[0078] ■ Figure 1 is an axonometric view of an anchoring device for rods according to a first embodiment of the present invention, wherein the device is in a first operating condition;

[0079] ■ Figure 2 is an axonometric view of the device of Figure 1 in a second operating condition;

[0080] ■ Figure 3 is an axonometric view of the anchoring device for rods according to a second embodiment of the present invention, wherein the device is in a first operating condition;

[0081] ■ Figure 4 is an axonometric view of the device of Figure 3 in a second operating condition;

[0082] ■ Figure 5 is an axonometric view of the anchoring device for rods according to a third embodiment of the present invention, wherein the device is in a first operating condition;

[0083] ■ Figure 6 is an axonometric view of the device of Figure 5 in a second operating condition;

[0084] ■ Figure 7 is a partially sectioned side view of the device of Figure 1 ;

[0085] ■ Figure 8 is a partially sectioned side view of the device of Figure 2;

[0086] ■ Figure 9 is a sectioned view of the device of Figure 7, according to the section line

[0087] A-A;

[0088] ■ Figure 10 is an enlarged detail of Figure 9;

[0089] ■ Figure 11 is a partially sectioned side view of the device of Figure 5;

[0090] ■ Figure 12 is a partially sectioned side view of the device of Figure 6;

[0091] ■ Figure 13 is a sectioned view of the device of Figure 11 , according to the section line A’-A’;

[0092] ■ Figure 14 is a first enlarged detail of Figure 13;

[0093] ■ Figure 15 is a second enlarged detail of Figure 13;

[0094] ■ Figure 16 is a partially sectioned side view of the device of Figure 3;

[0095] ■ Figure 17 is a partially sectioned side view of the device of Figure 4;

[0096] ■ Figure 18 is a schematic and simplified representation of the anchoring system according to the present invention, comprising the device of Figure 1 in an inactive, or resting, condition;

[0097] ■ Figure 19 is a schematic and simplified representation of the anchoring system according to the present invention, comprising the device of Figure 2 in in an active, or anchoring, condition.

[0098] Detailed description of preferred embodiments

[0099] The present patent describes a solution capable of determining the geotechnical characteristics of the soils during the installation phase, the presence of possible local anomalies etc.), improving the anchoring performances, by overcoming the limitations of the existing technologies and offering a safer, reliable and easy-to-implement fixing method.

[0100] The anchoring system, with the device for anchoring rods, is devised to be used in perforation holes and provides the deformation of a sacrificial cylinder, or external cylinder, external to the structure of the device, suitably sectioned longitudinally, by means of mechanic moving kinematics (Table 1 / 9, Figure 1 , Figure 2). The bar forming the device is hollow and it is connected to an internal chamber in the internal cylinder.

[0101] The mechanism activation is implemented through an external hydraulic pump equipped with manometer, which allows the sliding of a piston inserted in the internal chamber, provided with a vent hole.

[0102] The pressure sealing of the chamber is guaranteed until the extreme position of the piston, and once reached, the light of the vent hole provides for depressurization of the chamber, by putting in communication the internal chamber with the external environment. In case of additional device installed on the same rod, the vent hole will act as power supply to subsequent anchoring.

[0103] The device opening phase is then controlled during the phase of injection in the system, showing on the manometer the increase in pressure linked to the deformation of the external sacrificial cylinder and to the resistance opposed by the soil, to record then a sudden drop in pressure when perfect installation has occurred.

[0104] The pressures reached during the implementation phase will therefore provide valuable information about the resistance provided by the area in which anchoring has been installed.

[0105] Suitable formulations allow to connect the resistance opposed by the soil to the geotechnical characteristics of the same and then to the load-bearing capability of the rod.

[0106] On one same rod several devices can be positioned, at different depths (Table 2 / 9, Figure 3, Figure 4), in single configuration (Table 1 / 9, Figure 1 , Figure 2) or double configuration (Table 3 / 9, Figure 5, Figure 6).

[0107] The device, the patent relates to, is detailed hereinafter by making reference to the enclosed tables.

[0108] Table 1 / 9 shows the device in the single configuration, in inactive position (Figure 1) and active position (Figure 2).

[0109] Table 2 / 9 shows the two devices in single configuration, connected through interconnection tube, in inactive position (Figure 3) and active position (Figure 4).

[0110] Table 3 / 9 shows the device in the double configuration, in inactive position (Figure 5) and active position (Figure 6).

[0111] Table 4 / 9 shows the device in the single configuration in the two positions (Figure 7, Figure 8), by making observable the details of the external cylinder (a, 15), of the internal structural cylinder, or the main body of the device (b, 11), of the piston (c, 12), of the abutment pin (d, 32), of the power supply hollow bar, that is of the rod which may also consists of strands or solid bars (e, 101), of the sliding, or guiding, slots, (f, 22) on the external cylinder and of the vent hole (g, 25) or power hole of possible subsequent device.

[0112] Table 5 / 9 has the section of the single tube (Figure 9). The system for hooking the piston (c, 12) with the pin (e, 32), integral with the sacrificial external cylinder (a, 15) is detailed (Figure 10).

[0113] Table 6 / 9 shows the device in the double configuration in the two positions (Figure 11 , Figure 12), by making observable the details of the two sacrificial external cylinders(a), of the internal cylinder, or of the main body, (b, 11), of the single piston (c, 12), of the two abutment pins (d, 32), of the hollow bar of the rod (e, 101), of the sliding slots (f, 22) on both sacrificial external cylinders and of the vent hole (g, 25).

[0114] Table 7 / 9 has the section of the double device (Figure 13). The systems for hooking the pins (d, 32), integral with the external cylinders (a, 15), with the single piston (c, 12), are represented in detail (Figure 14, Figure 15).

[0115] Table 8 / 9 has two single devices assembled at different depth, in closed configuration (Figure 16) and open configuration (Figure 17), wherein the sealing chambers, or internal chambers (h, 20) and the interconnection small tube (i, 38) are visible.

[0116] Ultimately, the kinematics for activating the anchoring device provides for the sliding of the piston, coupled to a pin integral with the external cylinder, which allows the deformation thereof.

[0117] The sliding of the pin, coupled to the piston, is made possible by the presence of two slots obtained on the internal cylinder.

[0118] The anchoring is connected to the rod through thread, welding or glueing.

[0119] The so-described anchoring system, in case of installation in dense soils or rocky material, allows to implement an effective anchoring since during deformation the external sacrificial tube, that is the external cylinder, fits into the free space of the hole, by adapting thereto and exerting a compressive force on the whole.

[0120] On the contrary, in case of anchoring seats in not dense soils, the sacrificial tube, that is the external cylinder, deforming, will tend to introduce in the hole walls, by mobilizing the resistance of a higher soil volume and moreover not disturbed by the perforation, then even with greater resistance.

[0121] In both cases, a substantial increase in the anchoring performances is obtained, by allowing to transfer greater loads with respect to the traditional systems, by allowing then to apply, the geometries being the same, greater loads.

[0122] The anchoring system which is meant to be patented, then, allows to determine the effectiveness of the rod and to obtain effective and instantaneous anchoring since, as it is a mechanical anchoring, it can be used immediately, as soon as installed, since it does not require to wait for possible filling mixtures to mature. The present document then represents a substantial innovation with respect to the techniques in use and the patents referred to, by using an external sacrificial cylinder which allows to decouple the structural function of the system from the functional one and by offering an advantage in terms of design and performance.

[0123] The use of the “sacrificial” external cylinder, in fact, removes the size constraints linked to the thickness of the internal tube, which can assume even considerable sizes, since it has not to deform.

[0124] However, the most innovative aspect of the shown patent consists in characterizing immediately the densification of the soils and, through empiric and numeric correlations, testing the anchoring system and determining the effectiveness thereof, since a greater consistency of the soils and then a greater load-bearing capability of the rod corresponds to a greater pressure required to install the sacrificial external tube.

[0125] Then, it follows that the anchoring system allows to increase the geometry between rod and soil, to increase the capability of transferring the loads and to verify already during the installation phase the presence of possible geotechnical anomalies, such as cavities, less dense areas, etc.

[0126] Said in other words, the anchoring system is adapted to determine the geotechnical resistance of a rod, the mechanical characteristics of soils and to improve the anchoring performance by deforming a sacrificial cylinder made of steel or composite material, with mechanical movement, actuated hydraulically.

[0127] Preferably, the anchoring system can be driven into the soil or installed in a borehole. Preferably, the anchoring system allows to determine the geotechnical characteristics of the soils during the installation phase and then the load-bearing capability of the rod.

[0128] Preferably, the anchoring system allows to test the rod on which it is installed.

[0129] Preferably, the device allows to detect during the installation phase geotechnical anomalies, such as cavities or pockets of loosened soils.

[0130] Preferably, by means of the device it is possible to use the rod without requiring cementation or use of other mixtures.

[0131] Preferably, by means of the device, the rod can be used soon after the activation of the anchoring mechanism.

[0132] Preferably, the device (Table 4 / 9, Figure 7) consists of at least an external sacrificial cylinder (a, 15) and an internal cylinder (b, 11).

[0133] Preferably, the internal cylinder can even assume considerable thicknesses, since it does not have to deform. Preferably, the device can be implemented in single configuration (Table 1 / 9, Figure 2) or double configuration (Table 3 / 9, Figure 6).

[0134] In order to better understand the present invention the embodiments and the above- mentioned concepts will be described with greater detail and clarity hereinafter. It is to be noted that even numbering of parts, or elements, of the device, or of the system, will be updated and made clearer for a better comprehension of the invention.

[0135] As already specified above, the invention relates to a device 10 for anchoring rods (Figures 1-17), an anchoring system 100 (Figures 18 and 19) and the relative anchoring method.

[0136] The device 10 comprises at least:

[0137] ■ a hollow main body 11 , which develops along a longitudinal axis L;

[0138] ■ a piston 12 arranged inside the main body 11 and configured to be actuated hydraulically by means of a hydraulic pump 103 to slide in the main body 11 between a first position P1 and a second position P2; and

[0139] ■ at least an external cylinder 15 associated externally to a terminal portion of the main body 11 and configured to deform in at least two deformation directions when subjected to a pushing mechanical motion exerted by the piston 12, wherein a first deformation direction is parallel to the longitudinal axis L and a second deformation direction is transversal to the longitudinal axis L.

[0140] In particular, as illustrated in Figures 1-17, the main body 11 , the piston 12 and the external cylinder 15 are coaxial to each other, with reference to the longitudinal axis L.

[0141] The main body 11 is configured to be associated to a rod 101 on the opposite side with respect to the position of the external cylinder 15. In other words, the main body 11 , at an initial end thereof, opposite to the terminal portion thereto the external cylinder 15 is associated, can be fixed to a lower end 102 of a rod 101.

[0142] The main body 11 has a cylindrical shape, effectively defining a main internal cylinder with reference to the external cylinder 15, and comprises a fluid-tight internal chamber 20.

[0143] Moreover, the main body 11 extends along the longitudinal axis between at least a terminal connection part 16 and a terminal interface part 17.

[0144] The connection part 16 is configured to be associated to the lower end 102 of the rod 101.

[0145] The interface part 17 can include, or be divided into, at least:

[0146] ■ an initial portion 19 directed towards the connection part 16 and occupied by the internal chamber 20,

[0147] ■ a final portion 21 bearing at least two guide slots 22 opposed to each other with respect to the longitudinal axis L.

[0148] It is to be noted that, when the external cylinder 15 is in a not deformed condition, it surrounds the whole final portion 21 of the interface part 17 and the herein present guide slots 22 are not exposed to view.

[0149] As illustrated in Figures 7-17, the internal chamber 20 is hollow and limited by side walls of the main body 11 , by an initial septum 23 and by a final septum 24 in spacedapart mutual relation, wherein the distance between the initial septum 23 and the final septum 24 defines the extension of the internal chamber 20 along the longitudinal axis L. It is to be noted that the initial septum 23 and the final septum 24 are transversal, in particular perpendicular, to the longitudinal axis L.

[0150] The internal chamber 20 is configured to contain a liquid under pressure for actuating the piston 12, and to limit, with its longitudinal extension, an advance stroke of the latter.

[0151] In other words, the extension of the internal chamber 20 along the longitudinal axis L limits the advance stroke of the piston 12.

[0152] A portion of the internal chamber 20 is occupied by a part of the piston 12 equipped with a stop ring 26, protruding with respect to the body of the piston 12 and configured to abut, under the action of the action of the liquid under pressure, against the final septum 24 of the internal chamber 20, by determining the end of stroke of the piston 12. Under “end of stroke” a limit is meant beyond which the piston 12 cannot advance any more.

[0153] In other words, the piston 12 comprises at least a stop ring 26, protruding with respect to the body of the piston 12 and adapted to cooperate, inside the internal chamber 20, with the final septum 24, to abut thereon and determine the end of stroke of the piston 12. That is to say that, when the piston 12 is in the first position P1 , the stop ring 26 is in contact with the initial septum 23, whereas when the piston 12 is in the second position P2, the stop ring is in abutment, or in contact, with the final septum 24.

[0154] It is to be noted that an inactive, or resting, condition of the device 10 corresponds to the first position P1 of the piston 12 and that an active, or anchoring, condition, of the device 10 corresponds to the second position P2 of the piston 12.

[0155] For a greater comprehension, the device 10 is represented in the inactive condition in Figures 1 , 3, 5, 7, 11 , 16 and 18, whereas it is represented in the active condition in Figures 2, 4, 6, 8, 12, 17 and 19.

[0156] The internal chamber 20 bears a vent hole 25 adapted to put in communication the internal chamber 20 with outside. The vent hole 25 is implemented in a terminal area of the internal chamber 20, in a position so as to allow the evacuation of the liquid under pressure only when the piston 12 reaches the end of stroke, or when it is in the second position P2 (Figures 8, 12 and 17).

[0157] In other words, the vent hole 25 is implemented close to the final septum 22 and it allows to evacuate the liquid under pressure introduced into the internal chamber 20, only when the stop ring 23 abuts on the final septum 22.

[0158] The liquid evacuation involves the depressurization of the internal chamber 20.

[0159] It is to be noted that the main body 11 of the device 10 has a greater thickness than that of the external cylinder 15, since it has to be subjected to deformations due to the liquid pressure inside the internal chamber.

[0160] On the contrary, the external cylinder 15 has to result deformable. In particular, the external cylinder 15 is made of steel, or composite material.

[0161] According to an aspect of the present invention, the external cylinder 15 develops along the longitudinal axis L between a first end portion 27 and a second end portion 28.

[0162] The external cylinder 15 comprises an expandible central portion 29 comprising a plurality of deformable flaps 30 connected, at their own opposite ends, to the first end portion 27 and to the second end portion 28, respectively.

[0163] In particular, a not deformed condition of the flaps 30 corresponds to the first position P1 of the piston 12, whereas a deformed condition of the flaps 30 corresponds to the second position P2 of the piston 12.

[0164] Preferably, at least one between the first 27 and second 28 end portion is configured to move towards the other one as a result of the deformation along the first deformation direction, thus leading to the expansion of the expandible central portion 29.

[0165] In other words, the piston 12, as a result of the liquid under pressure, is configured to slide inside the main body 11 and bring in deformation the external cylinder 15 bringing one between the first 27 and second 28 end portion closer to the other one, thus determining the deformation along the first deformation direction.

[0166] More preferably, by means of the stress exerted by the piston 12, the first end portion 27 is configured to be approached to the second end portion 29.

[0167] Moreover, as a result of the approaching of the first end portion 27 to the second end portion 29, the flaps 30 are configured to deform plastically in radial direction to the main body 11 , that is along the second deformation direction, going from a not deformed condition, wherein they have rectilinear development, parallel to the longitudinal axis L, to a deformed condition, wherein they have an arched shape, or an inverted “V”-like shape, with reference to the longitudinal axis L. In other words, in relation to the deformation along the first deformation direction, the flaps 30 are configured to go from a not deformed condition, wherein they have rectilinear development, parallel to the longitudinal axis L, to a deformed condition, wherein they are in an arched configuration, or an inverted “V”-like shape, with reference to the longitudinal axis L, thus determining a deformation along the second deformation direction.

[0168] Preferably, the external cylinder 15 is provided with an abutment element, or abutment pin, 32 removably associated to the first end portion 27 and arranged transversely to the longitudinal axis L.

[0169] The abutment element 32 is configured to cooperate both with a head 24 of the piston 12, to be pushed by it during the action of the piston 12, and with guide slots 22 of the main body 11 , to guide the shifting of the first end portion 27 towards the second end portion 28 during the action of the piston 12.

[0170] In other words, the piston 12 comprises at least a head 24 adapted to contact the abutment element 32 to push the first end portion 27 towards the second end portion 28 and causing both the deformation along the first deformation direction and the deformation of the flaps 30, along the second deformation direction.

[0171] The approaching between the first end portion 27 and the second end portion 28, that is the deformation of the external cylinder 15 along the first deformation direction, is correctly favoured by the cooperation of terminal ends of the abutment element 32 with the respective guide slots 22.

[0172] As illustrated in detail in Figures 10, 14 and 15, the abutment element 32 is shaped like a pin transversal to the longitudinal axis L and it is inserted in removable way in two holes 33 obtained in the first end portion 27 of the external cylinder 15.

[0173] Specifically, the abutment element 32 comprises a central body 34 thereon, in use, the piston 12 abuts, and two protruding ends 35 with respect to the external cylinder 15 adapted to cooperate with the respective guide slots 22 during the action of the piston 12. Respective means for releasable fixing 36 are associated to the protruding ends 35 to lock the abutment element 32 to the external cylinder 15.

[0174] For example, each protruding end 35 of the abutment element 32 bears a hole and the releasable fixing means 36 is defined by split pins, each one thereof is inserted in a respective hole so as to lock firmly the abutment element 32 to the body of the external cylinder 15.

[0175] In this way a simple and reversible connection of the abutment element 32 is obtained, which simplifies the implementation of the device 10 and possible maintenance procedures.

[0176] According to a first embodiment, the main body 11 comprises a connection part 16 and an interface part 17 (Figures 1 and 2). According to a second embodiment, illustrated in Figures 5, 6, 11 , 12 and 13, the main body 11 comprises a connection part 16 and an interface part 17, wherein the latter is divided into:

[0177] ■ an initial portion 19 as described previously;

[0178] ■ a central portion 37; and

[0179] ■ a final portion 21.

[0180] The central portion 26 and the final portion 21 are substantially identical to each other, that is they bear at least two guide slots 22 opposed to each other with respect to the longitudinal axis L.

[0181] The device 10 then comprises two deformable external cylinders 15 which surround the central portion 37 and the final portion 21 , respectively, when they are in a not deformed condition. The piston 12 is shaped with two heads 14, each one adapted to act on a corresponding abutment element 32 associated to a respective external cylinder 15.

[0182] According to a third embodiment, illustrated in Figures 3, 4, 16 and 17, the main body 11 comprises and additional connection part 16’ and an additional interface part 17’, then overall a first connection part 16, a first interface part 17, a second connection part 16’ and a second interface part 17’. Specifically, the first connection part 16 is configured to be connected to a rod 101 at an opposite end with respect to the first interface part 17.

[0183] The second interface part 17’ is interposed between the first connection part 16 and the second connection part 16’, with the respective initial portion 19 directed towards the first connection part 16. Moreover, the first interface part 17 is connected to the second connection part 16’, with the respective initial portion 19 directed towards the latter.

[0184] In this case, the device 10 then comprises two deformable external cylinders 15, two internal chambers 20 and the piston 12 is configured to have two parts bearing respective stop rings 26, as well as two heads 14, wherein each stop ring 26 is adapted to cooperate with a corresponding final septum 24 of each internal chamber 20, and wherein each head 14 is adapted to cooperate with a corresponding abutment element 32. In this case, each internal chamber 20 is in fluidic communication with the other one, for the transmission of the liquid under pressure, for example by means of a flexible interconnection small tube 38.

[0185] Preferably the interconnection small tube 38 has an end connected to the vent hole 25 of the sealing chamber 20 of the first connection part 16 and another end connected to the sealing chamber 20 of the second connection part 16’.

[0186] The anchoring system 100, schematically represented in Figures 18 and 19, comprises at least: ■ the rod 101 configured to be inserted in a hole made in a soil to be stabilized;

[0187] ■ the device 10 as described previously, associated to the lower end 102 of the rod 101 ; and

[0188] ■ a hydraulic pump 103 operatively associated at least al piston 12 and configured to pump liquid under pressure inside the device 10 to actuate the piston 12, by moving it from the first position P1 (Figure 18) to the second position P2 (Figure 19).

[0189] It is to be noted that the rod 101 comprises a body which can be defined by a hollow tube, a strand, or a solid bar.

[0190] The hydraulic pump 103 can be of known type. Preferably, the hydraulic pump 103 can comprise a delivery pipe, not visible in the drawings, connected to a corresponding internal chamber 20 of the device 10 to inject therein the liquid under pressure.

[0191] For example, the delivery pipe can be inside the rod 101 , when the latter has a hollow body. Alternatively, in case the rod 101 comprises a body defined by a strand or a solid bar, the delivery pipe can be arranged outside and can have the function of a disposable pipe.

[0192] Preferably, the liquid used for actuating the piston 12 is water.

[0193] This has the advantage that when the liquid is evacuated through the vent hole 25, no environmental contaminations or polluting residues are produced in the surrounding soil.

[0194] The anchoring system 100 further comprises a manometer 105 operatively associated to the hydraulic pump 103 and configured to detect the liquid pressure inside the device 10, that is inside the internal chamber 20. The detection of the liquid pressure indicates the resistance exerted by the surrounding soil on the plurality of flaps 30 in deformation.

[0195] In fact, by means of specific formulations, not inserted in the present document for description simplicity, it is possible to correlate the liquid pressure, that produces the push of the piston 12, with the resistance that the soil produces on the flaps 30 in deformation. Under the expression “in deformation” the passage of the flaps 30 from the not deformed condition to the deformed condition is meant.

[0196] In this way, there is the advantage that without the need for complex systems for checking or adjusting the flow of the liquid under pressure, from the deformation of the expandible central portion 29, thus of the flaps 30, an estimate of the geotechnical resistance of the rod 101 , thereto determined mechanical characteristics of the surrounding soil correspond, can be obtained indirectly, by means of formulations. The present invention also relates to the anchoring method to determine the geotechnical resistance of a rod 101 , the mechanical characteristics of soils and to improve anchoring performance by using the anchoring system 100.

[0197] In particular, the method mainly comprises:

[0198] ■ an initial insertion phase;

[0199] ■ an activation phase;

[0200] ■ a deformation phase, with consequent final anchoring.

[0201] In the insertion phase the device 10 is associated to a lower end 102 of the rod 101 and inserted in a hole implemented in a soil to be stabilized.

[0202] In this initial phase, the device 10, just inserted in the hole, is in an inactive condition, with the piston 12 present inside thereof which in is in the first position P1.

[0203] In the activation phase, the hydraulic pump 103 starts pumping the liquid under pressure inside the device 10, in particular inside the corresponding internal chamber 20, to actuate consequently the piston 12.

[0204] In the deformation phase, the piston 12 is progressively pushed by means of the liquid under pressure inserted in the corresponding internal chamber 20, going from the first position P1 (Figure 18) to the second position P2 (Figure 19).

[0205] Such passage causes the approaching of the first end portion 27 towards the second end portion 28 and the expansion of the expandible part 29 of the corresponding external cylinder 15 and the deformation of the plurality of flaps 30. In this way, the passage of the device 10 to the active, or anchoring, condition takes place.

[0206] During the deformation phase, the manometer 105 detects continuously the liquid pressure inside the device, or inside the internal chamber 20, thus obtaining a corresponding indication of the resistance exerted by the surrounding soil on the flaps 30 in deformation.

[0207] Such detection allows to determine indirectly also the mechanical characteristics of the soil surrounding the external cylinder 15.

[0208] In the final part of the deformation phase, when the piston 12 arrives at the end of stroke, the liquid under pressure reaches the vent hole 25 and it is evacuated therethrough into the external environment, or in the surrounding soil. Such evacuation involves the depressurization of the internal chamber 20 and substantially determines the conclusion of the deformation phase, with the consequent final anchoring.

[0209] The descriptions and the details shown in the present document have been represented in the drawings and illustrated in depth. It is important noting that, although specific implementation modes have been highlighted, modifications equivalent to shape and details are possible without compromising the spirit and core of the invention. The terms used in this document has a descriptive and not limiting nature.

[0210] The present invention has been so far described with reference to preferred embodiments thereof. It is to be meant that other embodiments belonging to the same inventive core may exist, as defined by the protective scope of the here below reported claims.

[0211]

[0212] 10 anchoring device

[0213] 11 main body

[0214] 12 piston

[0215] 14 head

[0216] 15 external cylinder

[0217] 16, 16’ connection part, additional connection part

[0218] 17, 17’ interface part, additional interface part

[0219] 19 initial portion

[0220] 20 internal chamber

[0221] 21 final portion

[0222] 22 guide slots

[0223] 23 initial septum

[0224] 24 final septum

[0225] 25 vent hole

[0226] 26 stop ring

[0227] 27 first end portion

[0228] 28 second end portion

[0229] 29 expandible central portion

[0230] 30 flaps

[0231] 32 abutment element

[0232] 33 holes

[0233] 34 central body

[0234] 35 protruding ends

[0235] 36 releasable fixing means

[0236] 37 central portion

[0237] 38 interconnection small tube

[0238] 100 anchoring system

[0239] 101 rod

[0240] 102 lower end

[0241] 103 hydraulic pump

[0242] 105 manometer

[0243] L longitudinal axis

Claims

CLAIMS1. Anchoring device (10) adapted to be used in an anchoring system (100) configured to determine the geotechnical resistance of a rod, the mechanical characteristics of soils and / or to improve anchoring performance, wherein said device (10) comprises:■ a hollow main body (11), which develops along a longitudinal axis (L) between at least a terminal connection part (16) and a terminal interface part (17), and it is configured to be associated to a rod (101) at said connection part (16);■ a piston (12) arranged inside said main body (11) and configured to be actuated hydraulically by means of a hydraulic pump (103) to slide inside said main body (11), between a first position (P1), thereto an inactive, or resting, condition of said device (10) corresponds, and a second position (P2), thereto an active, or anchoring, condition of said device (10) corresponds,■ at least an external cylinder (15) arranged at said interface part (17), which develops along said longitudinal axis (L) between a first end portion (27) and a second end portion (28), and configured to deform according to at least a first deformation direction parallel to said longitudinal axis (L) and a second deformation direction transversal to said longitudinal axis (L), when subjected to a pushing mechanical motion exerted by said piston (12), wherein said main body (11), said piston (12) and said external cylinder (15) are mutually coaxial, wherein said external cylinder (15) is made of steel, or composite material, and comprises an expandible central portion (29) comprising a plurality of deformable flaps (30) connected, at their own opposite ends, to said first end portion (27) and to said second end portion (28), respectively, wherein a not deformed condition of said flaps (30) corresponds to said first position (P1) of said piston (12), and a deformed condition of said flaps (30) corresponds to said second position (P2) of said piston (12).

2. Device (10) according to claim 1 , wherein at least one between said first (27) and second (28) end portion is configured to move towards the other one as a result of said deformation along said first deformation direction, and wherein said flaps (30) are configured to deform plastically in radial direction to said main body (11) as a result of the approaching between said first (27) and second (28) end portion, along said second deformation direction, going from said not deformed condition, wherein they have rectilinear development, parallel to said longitudinal axis (L), to said deformed condition, wherein they have an arched shape, or an inverted V-like shape, with reference to said longitudinal axis (L).

3. Device (10) according to claim 1 or 2, wherein said main body (11) has a cylindrical shape and it comprises at least a fluid-tight internal chamber (20), configured tocontain a liquid under pressure for the actuation of said piston (12), wherein the extension of said internal chamber (20) along said longitudinal axis (L) limits the advance stroke of said piston (12).

4. Device (10) according to any one of the preceding claims, wherein said interface part (17) comprises at least:■ an initial portion (19) directed towards said connection part (16) and occupied by a fluid-tight internal chamber (20),■ a final portion (21) bearing at least two guide slots (22) opposed to each other with respect to said longitudinal axis (L), wherein said external cylinder (15) surrounds said final portion (21) when it is in a not deformed condition.

5. Device (10) according to the preceding claim, wherein said interface part (17) comprises, additionally, a central portion (36) interposed between said initial portion(19) and said final portion (21) and preferably identical to the latter, wherein an additional external cylinder (15) surrounds said central portion (36) when it is in a not deformed condition, and wherein said piston (12) is configured to act on each external cylinder (15) bringing both of them in deformation.

6. Device (10) according to claim 4, wherein said main body (11) comprises an additional connection part (16’) and an additional interface part (17’), wherein said connection part (16) is configured to be connected to a rod (101) at an opposite end with respect to said interface part (17), wherein said additional interface part (17’) is interposed between said connection part (16) and said additional connection part (16’), with the respective initial portion (19) directed towards said connection part (16), and wherein said interface part (17) is connected to said additional connection part (16’), with the respective initial portion (19) directed towards said additional connection part (16’).

7. Device (10) according to any one of claims 3 to 6, wherein the internal chamber(20) bears a vent hole (25) adapted to put in communication said internal chamber (20) with outside and implemented in a terminal area of the same in a position so as to allow the evacuation of the liquid under pressure only when said piston (12) is at the end of the stroke.

8. Device (10) according to any one of claims 3 to 7, wherein said external cylinder (15) is provided with an abutment element (32) removably associated to said first end portion (27), transversely to said longitudinal axis (L), and configured to cooperate both with a head (24) of said piston (12), to be pushed by it during the action of said piston (12), and with guide slots (22) of said main body (11), to guide the movement of said first end portion (27) towards said second end portion (28) during the action of said piston (12).

9. Device (10) according to claim 8, wherein said abutment element (32) is shaped like a pin inserted removably in two holes (33) obtained in said first end portion (27) and it comprises a central body (34) on which, in use, said head (24) of said piston (12) abuts and two protruding ends (35) with respect to said external cylinder (15), suitable to cooperate with the respective guide slots (22) during the action of the piston (12), wherein respective means for releasable fixing (36) are associated to said protruding ends (35) to lock the abutment element (32) to the external cylinder (15).

10. Anchoring system (100) configured to determine the geotechnical resistance of a rod (101), the mechanical characteristics of soils, or rocks, and / or to improve anchoring performance, wherein said anchoring system (100) comprises at least:■ a rod (101) configured to be inserted in a hole made in a soil, or a rock, to be stabilized;■ an anchoring device (10) according to any one of the preceding claims, configured to be associated to a lower end (102) of the rod (101); and■ a hydraulic pump (103) operatively associated at least to said piston (12) of said device (10) and configured to pump liquid under pressure inside said device (10) to actuate said piston (12), by moving it from said first position (P1) to said second position (P2).

11. Anchoring system (100) according to claim 10, comprising a manometer (105) operatively associated to said hydraulic pump (103) and configured to detect the liquid pressure inside said device (10) indicating the resistance exerted by the surrounding soil, or rock, on a plurality of flaps (30) in deformation of said at least an external cylinder (15) of said device (10).

12. An anchoring method to determine the geotechnical resistance of a rod (101), the mechanical characteristics of soils and / or to improve anchoring performance by using an anchoring system (100) according to one of claims 10 or 11 , said method comprising at least:■ an insertion phase, wherein an anchoring device (10) according to any one of claims 1 to 9 is associated to a lower end (102) of a rod (101) and inserted in a hole made in a soil, or a rock, to be stabilized, said device (10) being at first in an inactive, or resting, condition and said piston (12) being at first in said first position (P1),■ an activation phase, wherein a hydraulic pump (103) starts pumping a liquid under pressure inside said device (10), by consequently actuating said piston (12),■ a deformation phase, wherein said piston (12) is progressively pushed by means of the liquid under pressure, from said first position (P1) to said second position (P2), by causing the deformation of a plurality of flaps (30) of said atleast an external cylinder (15) of said device (10), thereto the passage to an active, or anchoring, condition of said device (10) corresponds.

13. Method according to claim 12, wherein in said activation phase, the liquid under pressure is introduced in at least a fluid-tight internal chamber (20) of said device (10), and wherein in said deformation phase, the liquid under pressure fills-in progressively said at least an internal chamber (20) by making the piston (12) to advance as far as reaching an end of stroke in said second position (P2).

14. Method according to claim 13, wherein when said piston (12) reaches the end of stroke, the liquid under pressure reaches a vent hole (25) implemented in a terminal area of said at least an internal chamber (20) and it is evacuated therethrough into the external environment.

15. Method according to any one of claims 13 to 14, wherein in said deformation phase, a manometer (105) operatively associated to said hydraulic pump (103), detects the liquid pressure inside said device (10) by obtaining a corresponding indication of the resistance exerted by the surrounding soil, or rock, on said plurality of flaps (30) in deformation.

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