Active detection device and method for anchor rod holding load in locked state

Abstract

The present invention discloses an active detection device and method for the load held by an anchor rod in a locked state, comprising a support ring, a spring and a displacement meter, wherein the support ring comprises two semicircular supports connected together by screws, and the semicircular supports comprise a locking ring, a locking ear, a support plate and a support leg, the locking rings of the two semicircular supports enclose a clamping space for clamping the anchor, the locking ear and the support plate are both arranged on the outer wall of the locking ring, the support leg is arranged on the support plate, the spring is sleeved on the support leg, and the displacement meter is arranged corresponding to the support ring. The device of the present invention is simple and can quickly detect the prestress or tension of the anchor rod, and improve the real on-site anchor rod tension data for evaluating the safety and stability of the project. The present invention also proposes a lift-off detection method for the load held by the anchor rod in a locked state, which has the advantages of convenient construction, simple operation and reliable detection results.

Description

Technical Field

[0001] The invention relates to an active detection device and a detection method for an anchor rod holding load in a locked state, and belongs to the technical field of building construction. Background Art

[0002] Anchor rods are widely used in geotechnical engineering. They realize the pull-out resistance by anchoring in stable strata, provide strong bearing force for supporting structures, anchoring structures, etc., and ensure the safety and stability of geotechnical anchoring projects. In actual projects, in order to effectively control the deformation of structures or soil, anchor rods are often prestressed in projects, and the locking size of the prestress is directly related to the safety of the project. However, due to construction and other reasons, there is often a large prestress loss after the prestress is tensioned and locked, resulting in a locking value that is less than or even far less than the designed prestress value, or the actual tension is far less than the designed axial tension, which poses a great safety hazard to the project. Once the anchor rod is locked, it is difficult to detect its true prestress or the actual tension it bears, which brings great technical challenges to prestressed anchoring projects.

[0003] The inventor retrieved the following relevant patent documents: (1) CN206902781U discloses a detection device and detection method for the outer side of the internal force of an anchor rod, wherein the detection device comprises an anchor rod, a reaction force mold, a perforated gasket, a magnetic standard, a displacement sensor, a matrix, and an anchor rod puller. The perforated gasket is arranged at the outer side wall of the clip of the clip-type anchor and is displaced in the cavity of the reaction force mold. The displacement sensor is located in the cavity. The side head of the displacement sensor contacts the displacement test point on the surface of the perforated gasket and pushes the perforated gasket against the outer side wall of the clip of the anchor when the clip is pressed. When the anchor rod is tensioned in stages, the displacement of the perforated gasket is observed. When the perforated gasket is displaced, the force reading applied by the anchor rod puller is recorded to determine the internal force value of the anchor rod. This method is too simple, resulting in the following serious problems: ① The perforated gasket is difficult or even impossible to displace. The reason is that the opening for the steel strand to pass through in the anchor of the locking anchor is a conical hole, and the conical hole is equipped with a clip to clamp the steel strand. The large mouth of the conical hole faces the free surface, and the small mouth of the conical hole faces the slope pile. When the steel strand is continuously subjected to force, the inner teeth of the clip clamp the steel strand tighter and tighter in the conical hole. When the puller is used to tension the steel strand on the outside, the clip clamps the steel strand, and the steel strand will be displaced during the tensioning process when the tensioning force is less than the internal force of the anchor rod; ② The anchor will not be displaced. Since the clip is placed in the conical hole of the anchor, the outer wall of the clip and the inner wall of the conical hole are both smooth surfaces. Even after the tensioning force is greater than the internal force of the anchor rod, the anchor will not be displaced upward under the action of gravity and the top pressure of the perforated gasket; ③ The error of the internal force of the test anchor rod is large. Since the displacement of the clip is not the corresponding displacement when the tension force reaches the internal force of the anchor rod, the anchor does not produce displacement. Therefore, there is a large error or the result cannot be measured by determining the corresponding tension force when the perforated gasket is displaced as the internal force value of the anchor rod. (2) CN107503386A discloses a detection device and method for the load held by the anchor rod body. The detection device includes a support bench, a jack, a dynamometer, a tool anchor and a dial indicator arranged in sequence from bottom to top along the axial direction of the anchor rod. The bottom surface of the support bench is supported on the pad of the waist beam of the completed anchor rod structure, and the top surface is in contact with the bottom surface of the jack. The support bench is fixed between the pad and the jack by the preload force of the jack. The top of the jack has a piston. The exposed free end of the anchor rod passes through the center of the support bench, the jack, the dynamometer and the tool anchor in sequence from bottom to top, and the top extends from the tool anchor. The tool anchor is fixedly connected to the upper part of the exposed free end of the anchor rod. The dynamometer is clamped between the piston and the tool anchor. The piston pushes the dynamometer. The dial indicator is installed on the tool anchor. When the displacement mutation on the load-displacement relationship curve is obvious, the load value corresponding to the starting point of the steep rise is taken as the load held by the anchor rod body.This method is theoretically feasible, that is, when the tension force is less than the holding load, the displacement of the tool anchor is theoretically the theoretical elongation of the steel strand between the tool anchor and the working anchor. When the tension force is greater than the holding load, the working anchor is unlocked, and the tensile deformation of the steel strand in the free section of the anchor rod is reflected in the deformation of the tool anchor, resulting in a sharp increase in deformation. Therefore, in theory, the mutation point of the load-displacement curve is the anchor rod holding load. However, in actual operation, there will be different degrees of errors due to the size of the holding load, resulting in the following problems:

[0004] ① The mutation point lags, and the test anchor holding load is too large. When the tension force is greater than the holding load, due to the gap between the clip and the steel strand, there will be a relative displacement between the clip and the steel strand. At this time, the clip is further locked into the cone hole of the anchor until the gap between the clip and the steel strand disappears. While the clip is further locked into the cone hole of the anchor, the tension force is increasing, and the displacement of the anchor is less than the displacement value of the steel strand, resulting in a lag in the mutation point of the load-displacement curve, that is, the tension force corresponding to the lag mutation point is greater than the anchor holding load; ② The greater the anchor holding load, the greater the error in the test result. Because the gap between the clip and the steel strand in the tool anchor continues to occur with the increase of tension force, when the holding load is large, the larger the gap that can be compressed, the more serious the displacement lag of the tool anchor, resulting in a greater error in the detection method. (3) CN108487334A discloses a construction method for detecting the holding load of prestressed anchor rods by the lift-off method. The construction method includes the following construction steps: pre-construction preparation, including the preparation of tools and various instruments; data collection, using the lift-off method to collect the load data and displacement data of the prestressed anchor; data analysis, analyzing the collected load data and displacement data to determine the holding load of the prestressed anchor. This method will have the problem of item ② in the aforementioned CN206902781U patent document. In addition, a thin and narrow steel sheet with a thickness of 1.0 mm is inserted between the working anchor and the steel pad for detection. When the tension force reaches the holding load, there is no separation between the anchor and the steel pad steel sheet, and due to the thickness of the steel sheet, there will be a problem of delay in confirming the separation of the entire section of the anchor and the steel pad, resulting in a larger detection holding load.

[0005] In view of this, the inventor of this case conducted in-depth research on the above-mentioned issues, which led to the emergence of this case. Summary of the invention

[0006] An object of the present invention is to provide an active detection device for the load held by an anchor rod in a locked state, which has the advantages of simple structure and quick installation. Another object of the present invention is to propose a lift-off detection method for the load held by an anchor rod in a locked state, which has the advantages of convenient construction, simple operation and reliable detection results.

[0007] In order to achieve the above object, the present invention adopts such technical solution:

[0008] The anchor rod in the locked state holds an active load detection device, including a bracket ring, a spring and a displacement meter, the bracket ring includes two semicircular brackets connected together by screws, the semicircular bracket includes a locking ring, a locking ear, a support plate and a support leg, the locking rings of the two semicircular brackets form a clamping space for clamping the anchor, the locking ear and the support plate are both arranged on the outer wall of the locking ring, the support leg is arranged on the support plate, the spring is sleeved on the support leg, and the displacement meter is arranged corresponding to the bracket ring.

[0009] As a preferred embodiment of the present invention, the support leg is arranged at one end of the support plate and is perpendicular to the support plate.

[0010] As a preferred embodiment of the present invention, a threading hole is provided on the locking ear of the semicircular bracket, the screw is passed through the threading hole, and a nut is provided on the screw.

[0011] As a preferred embodiment of the present invention, a tapered hole is provided on the anchor, a plurality of clips are provided in the tapered hole, a reinforcement body is clamped in the plurality of clips, a pad is provided at one end of the anchor, the spring is arranged between the support plate and the pad, and the natural length of the spring is greater than the net distance from the support plate to the pad.

[0012] As a preferred embodiment of the present invention, the pad is provided with a magnetic base, the magnetic base is provided with a connecting rod, the displacement meter is mounted on the connecting rod, and the pointer of the displacement meter abuts against the support plate.

[0013] As a preferred embodiment of the present invention, two locking ears are provided on each of the semicircular brackets, and one supporting plate is provided on each of the semicircular brackets.

[0014] As a preferred embodiment of the present invention, there are two displacement meters, and the two displacement meters are respectively arranged corresponding to the two support plates.

[0015] The method for detecting the load held by the anchor in the locked state includes the following construction steps:

[0016] (1) Bracket ring fixed installation

[0017] First, the spring is put on the supporting leg, and then the semicircular bracket is put on the outside of the anchor, and the spring on the supporting leg is pressed against the pad under the anchor, and then the two semicircular brackets are fastened to the anchor by screws and nuts on the locking ears;

[0018] (2) Displacement meter installation

[0019] Fixing a magnetic table seat with a displacement meter installed on the pad, adjusting the displacement meter so that the pointer vertically abuts against the support plate, and symmetrically installing the displacement meter on the support plate of the semicircular bracket;

[0020] (3) Tension test

[0021] A jack is used to tension the tendon body, and the tensioning force of the jack and the lift-off displacement tested by the displacement meter are connected to the signal collector, and a tensioning force and lift-off displacement average value curve is established in the signal collector; when the tensioning force is less than the holding load of the anchor rod, the tendon body is still in a locked state, the anchor is pressed against the pad, and the lift-off displacement is always zero, and this process is the unlocking process; when the tensioning force increases to the holding load of the anchor rod, the clip that locks the tendon body is about to detach from the tendon body but does not detach; when the tensioning force increases to exceed the holding load of the anchor rod, the clip detaches from the anchor, and the tendon body is unlocked. At this time, the bracket ring moves upward under the pushing action of the spring, and the lift-off displacement is greater than zero, and continues to increase with the increase of the tensioning force. This process is the lift-off process;

[0022] (4) Holding load determination

[0023] By analyzing the tension force and lift-off displacement average value curve, the tension force corresponding to the starting point when the lift-off displacement average value is greater than zero can be obtained as the anchor holding load, that is, the intersection of the unlocking process curve and the lift-off process curve is the anchor holding load.

[0024] After adopting the technical solution of the present invention, the active detection device and method for the anchor rod holding load in the locked state have the following significant advantages: (1) Since the present invention adopts a bracket ring with a set compression spring to connect the working anchor, when the tension force of the anchor rod is equal to the holding load, the spring can actively and timely push the anchor, causing the anchor to displace in the direction of detaching from the pad; (2) Since the spring can respond in time to the moment when the tension force is equal to the holding load, the load-displacement curve on the model collector can actively and accurately record the unlocking process and the lifting process, so it can accurately reflect the turning points of the unlocking process curve and the lifting process curve, that is, accurately test the holding load of the anchor rod; (3) The detection device of the present invention has a simple structure, is easy to install, and has reliable test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a top view of the bracket ring of the present invention after installation.

[0026] Figure 2 For the present invention Figure 1 AA cross-section diagram.

[0027] Figure 3 For the present invention Figure 1 BB cross-section diagram.

[0028] Figure 4 It is a front view of the semicircular support of the present invention.

[0029] Figure 5 It is a top view of the semicircular bracket of the present invention.

[0030] Figure 6 It is a side view of the semicircular bracket of the present invention.

[0031] Figure 7 It is the average value curve of tension force and lift-off displacement.

[0032] In the figure:

[0033] 1 bracket ring 11 semicircular bracket 12 locking ring

[0034] 13 lock ear 14 threading hole 15 support plate

[0035] 16 Leg 17 Spring 18 Screw 19 Nut

[0036] 2 magnetic table base 21 connecting rod 3 displacement meter 31 pointer

[0037] 4 anchor 41 cone hole 42 clip 43 tendon

[0038] 5 pad 51 rib hole

[0039] 6 Support beam 61 Reinforcement hole

[0040] 7 Soil DETAILED DESCRIPTION

[0041] In order to further explain the technical solution of the present invention, the following is a detailed description in conjunction with the embodiments. Figure 1-Figure 7 The active detection device for the load held by the anchor rod in the locked state of the present invention includes a bracket ring 1, a spring 17 and a displacement meter 3. The bracket ring 1 includes two semicircular brackets 11 connected together by a screw 18, and the semicircular bracket 11 includes a locking ring 12, a locking ear 13, a support plate 15 and a support leg 16. The locking rings 12 of the two semicircular brackets 11 form a clamping space for clamping the anchor 4. The locking ear 13 and the support plate 15 are both arranged on the outer wall of the locking ring 12, the support leg 16 is arranged on the support plate 15, the spring 17 is sleeved on the support leg 16, and the displacement meter 3 is arranged corresponding to the bracket ring 1.

[0042] As a preferred embodiment of the present invention, the support leg 16 is disposed at one end of the support plate 15 and is perpendicular to the support plate 15 .

[0043] As a preferred embodiment of the present invention, a threading hole 14 is provided on the locking ear 13 of the semicircular bracket 11 , the screw 18 is passed through the threading hole 14 , and a nut 19 is provided on the screw 18 .

[0044] As a preferred embodiment of the present invention, the anchor 4 is provided with a plurality of tapered holes 41, each tapered hole 41 is provided with a plurality of clips 42, in the embodiment, each tapered hole 41 is provided with two clips 42, a reinforcement 43 is clamped in the plurality of clips 42, one end of the anchor 4 is provided with a pad 5, the pad 5 is against the support beam 6, the support beam 6 is provided with a reinforcement hole 61, the reinforcement 43 passes through the reinforcement hole 61 and passes into the soil 7. The spring 17 is provided between the support plate 15 and the pad 5, and the natural length of the spring 17 is greater than the net distance from the support plate 15 to the pad 5.

[0045] As a preferred embodiment of the present invention, a magnetic base 2 is provided on the pad 5, a connecting rod 21 is provided on the magnetic base 2, the connecting rod 21 is arranged in the horizontal direction, the displacement meter 3 is installed on the connecting rod 21, the pointer 31 of the displacement meter 3 is against the support plate 15, and the lifting displacement of the support plate 15 relative to the anchor 4 is tested, and the displacement meter 3 is connected to the signal collector.

[0046] As a preferred embodiment of the present invention, two locking ears 13 are provided on each of the semicircular brackets 11, and the two locking ears 13 are respectively provided at both ends of the locking ring 12. A support plate 15 is provided on each of the semicircular brackets 11, and the support plate 15 is provided in the middle of the locking ring 12.

[0047] As a preferred embodiment of the present invention, there are two displacement meters 3 , and the two displacement meters 3 are respectively arranged corresponding to the two support plates 15 .

[0048] The present invention also proposes a method for detecting the lifting of the load held by the anchor rod in a locked state, comprising the following construction steps:

[0049] (1) Bracket ring fixed installation

[0050] First, insert the spring 17 onto the leg 16, then insert the semicircular bracket 11 onto the outside of the anchor 4, and make the spring 17 on the leg 16 press against the pad 5 located below the anchor 4, and then use the screw 18 and nut 19 on the locking ear 13 to fasten the two semicircular brackets 11 to the anchor 4.

[0051] (2) Displacement meter installation

[0052] The magnetic base 2 with the displacement meter 3 installed is fixed on the pad 5, and the displacement meter 3 is adjusted so that the pointer 31 vertically abuts against the support plate 15. The displacement meter 3 is symmetrically installed on the support plate 15 of the semicircular bracket 11.

[0053] (3) Tension test

[0054] The tendon 43 is tensioned by a jack, and the tensioning force of the jack and the lift-off displacement tested by the displacement meter 3 are connected to the signal collector, and a tensioning force and lift-off displacement average curve is established in the signal collector. When the tensioning force is less than the holding load of the anchor rod, the tendon 43 is still in a locked state, the anchor 4 is pressed against the pad 5, and the lift-off displacement is always zero. This process is the unlocking process; when the tensioning force increases to the holding load of the anchor rod, the clip 42 locking the tendon 43 is about to be separated from the tendon 43 but does not separate; when the tensioning force increases to exceed the holding load of the anchor rod, the clip 42 is separated from the anchor 4, and the tendon 43 is unlocked. At this time, the bracket ring 1 moves upward under the pushing action of the spring 17, and the lift-off displacement is greater than zero, and continues to increase with the increase of the tensioning force. This process is the lift-off process.

[0055] (4) Holding load determination

[0056] By analyzing the tension force and lift-off displacement average value curve, the tension force corresponding to the starting point when the lift-off displacement average value is greater than zero can be obtained as the anchor holding load, that is, the intersection of the unlocking process curve and the lift-off process curve is the anchor holding load.

[0057] After adopting the technical solution of the present invention, the anchor holding load active detection device and lift-off detection method can be used to conveniently, quickly and accurately detect the anchor holding load in the locked state, thereby improving the actual anchor tension for the safety and stability analysis and evaluation of the project.

[0058] The product form of the present invention is not limited to the embodiments of this case. Any appropriate changes or modifications made by anyone with similar ideas should be deemed to be within the patent scope of the present invention.

Claims

1. An active detection device for the load held by the anchor in the locked state, characterized in that: It includes a bracket ring, a spring and a displacement meter, the bracket ring includes two semicircular brackets connected together by screws, the semicircular bracket includes a locking ring, a locking ear, a support plate and a support leg, the locking rings of the two semicircular brackets form a clamping space for clamping the anchor, the locking ear and the support plate are both arranged on the outer wall of the locking ring, the support leg is arranged on the support plate, the spring is sleeved on the support leg, and the displacement meter is arranged corresponding to the bracket ring; two locking ears are arranged on each of the semicircular brackets, and one support plate is arranged on each of the semicircular brackets.

2. The active detection device for anchor rod load in the locked state as claimed in claim 1, characterized in that: The supporting leg is arranged at one end of the supporting plate and is arranged perpendicular to the supporting plate.

3. The active detection device for anchor rod load in the locked state as claimed in claim 2, characterized in that: The locking ear of the semicircular bracket is provided with a threading hole, the screw is inserted into the threading hole, and a nut is arranged on the screw.

4. The active detection device for anchor rod load in the locked state as claimed in claim 3, characterized in that: The anchor is provided with a tapered hole, in which a plurality of clips are provided, and a tendon is clamped between the plurality of clips. A pad is provided at one end of the anchor, and the spring is arranged between the support plate and the pad, and the natural length of the spring is greater than the net distance from the support plate to the pad.

5. The active detection device for anchor rod load in the locked state as claimed in claim 1, characterized in that: There are two displacement meters, and the two displacement meters are respectively arranged corresponding to the two support plates.

6. A method for detecting the load held by an anchor in a locked state, characterized in that: The active detection device for anchor rod load in the locked state according to claim 4 comprises the following construction steps: (1) Bracket ring fixed installation First, the spring is put on the supporting leg, and then the semicircular bracket is put on the outside of the anchor, and the spring on the supporting leg is pressed against the pad under the anchor, and then the two semicircular brackets are fastened to the anchor by screws and nuts on the locking ears; (2) Displacement meter installation Fixing a magnetic table seat with a displacement meter installed on the pad, adjusting the displacement meter so that the pointer vertically abuts against the support plate, and symmetrically installing the displacement meter on the support plate of the semicircular bracket; (3) Tension test The tendon body is tensioned by a jack, and the tensioning force of the jack and the lift-off displacement tested by the displacement meter are connected to the signal collector, and a curve of the tensioning force and the lift-off displacement average value is established in the signal collector; when the tensioning force is less than the holding load of the anchor rod, the tendon body is still in a locked state, the anchor is pressed against the pad, and the lift-off displacement is always zero, and this process is the unlocking process; when the tensioning force increases to the holding load of the anchor rod, the clip that locks the tendon body is about to detach from the tendon body but does not detach; When the tension force increases to exceed the holding load of the anchor rod, the clip is separated from the anchor, and the tendon is unlocked. At this time, the bracket ring moves upward under the pushing action of the spring, and the lifting displacement is greater than zero, and continues to increase with the increase of the tension force. This process is the lifting process; (4) Holding load determination By analyzing the tension force and lift-off displacement average value curve, the tension force corresponding to the starting point when the lift-off displacement average value is greater than zero can be obtained as the anchor holding load.

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