A shotcrete adhesion testing device and method

Abstract

The application discloses a kind of shotcrete adhesion testing device and testing method, it is related to shotcrete adhesion testing technical field, including: test mould, test plate, support frame, pull rope component and tension component;Test mould is located in support frame side, top has chamber;The bottom surface of test plate can be attached and adhered to the surface of shotcrete to be measured filled in chamber;Support frame top is provided with pulley mechanism;Test plate and tension component are symmetrically arranged on the two sides of support frame and are all located below pulley mechanism;Pull rope component one end is fixed with test plate top surface, the other end passes through pulley mechanism and is fixed with tension component;Tension component provides tension to test plate by pull rope component, to measure the adhesion between test plate and test mould filled shotcrete to be measured size.The application has the characteristics that device structure is simple, testing operation is quick and accurate.

Description

Technical Field

[0001] This invention relates to the field of shotcrete adhesion testing technology, and in particular to a shotcrete adhesion testing device and testing method. Background Technology

[0002] Shotcrete is commonly used for the initial support of tunnels. Shotcrete is a type of concrete that is sprayed onto the tunnel bedrock using compressed air or other power sources to harden. Due to its fast construction speed, simple process, and flexible operation, shotcrete is widely used in tunnels, coal mine shafts, slope protection, and maintenance projects. Composite lining structures, composed of shotcrete, anchor bolts, and cast-in-place secondary lining concrete, are the mainstream technical solution for tunnel support in my country. In composite lining structures, shotcrete plays a crucial role in forming the support structure, controlling rock relaxation and deformation, and preventing rock degradation.

[0003] One of the key indicators for evaluating the performance of shotcrete is the rebound rate, which is the ratio of concrete that bounces off the rock surface after being sprayed to the amount of concrete that adheres to the surface. Besides the process and spraying equipment, the rebound rate is primarily influenced by the adhesion of the shotcrete. However, there is currently no effective method to characterize the adhesion between fresh shotcrete and the rock surface in its plastic state. Existing indicators used domestically and internationally to evaluate the bond performance between shotcrete and surrounding rock are bond strength tests. These tests mainly include the "pre-existing specimen pull-out method," the "core drill pull-out method," and the "sprayed slab cutting and splitting method." All three methods test the bond strength between the hardened shotcrete and the surface, and do not reflect the adhesion between fresh shotcrete and the rock surface immediately after spraying. Appendix M of GB 50086-2015 "Technical Specification for Rock and Soil Anchors and Shotcrete Support Engineering", Appendix I of DL / T5181-2017 "Construction Specification for Anchor and Shotcrete Support in Hydropower and Water Conservancy Projects", and Appendix D of JGJ / T 372-2016 "Technical Specification for Application of Shotcrete" introduce the test procedure of the "pre-reserved specimen pull-out method"; the test procedure of the "core drill pull-out method" is introduced in GB 50086-2015 "Technical Specification for Rock and Soil Anchors and Shotcrete Support Engineering", DL / T 5181-2017 "Construction Specification for Anchor and Shotcrete Support in Hydropower and Water Conservancy Projects", JGJ / T 372-2016 "Technical Specification for Application of Shotcrete", and DINEN 14488-4:2008 'Testing sprayed concrete - Part 4: Bond strength of cores by direct tension'; DL / T Appendix I of the 5181-2017 "Code for Construction of Anchor-Sprayed Support in Hydropower and Water Conservancy Projects" introduces the testing procedures for the "sprayed concrete slab cutting and splitting method". However, in the "pre-reserved specimen pull-out method", the annular groove is difficult to obtain due to the rapid hardening of the sprayed concrete, and the trenching process is prone to damage to the specimen; the pre-embedded tie rod is difficult to ensure that the load is not eccentric; in the "core drilling pull-out method", the oscillation of the drilling rig may damage the concrete specimen, and the pre-embedded tie rod is also difficult to ensure that the load is not eccentric; in the "sprayed concrete slab cutting and splitting method", it is difficult to ensure that the contact surface between the sprayed concrete and the rock is on the same vertical plane, and the shear force causes the test results to be too high.

[0004] Therefore, how to provide a shotcrete adhesion testing device and method that can evaluate the bonding performance between concrete and surrounding rock in a plastic state in the laboratory, obtain the adhesion force between the tested shotcrete and rock with simple calculation, and have the characteristics of simple device structure and quick testing operation is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention proposes a shotcrete adhesion testing device and method to solve the above-mentioned technical problems. The shotcrete adhesion testing device and method proposed in this invention can evaluate the bonding performance between concrete and surrounding rock in a plastic state in a laboratory setting. The adhesion force between the tested shotcrete and the rock can be obtained through simple calculation, and it has the advantages of simple device structure and quick testing operation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] One aspect of the present invention provides a shotcrete adhesion testing device, comprising: a mold, a test plate, a support frame, a rope assembly, and a tension assembly;

[0008] The test mold is located on the side of the support frame, and has a top chamber for filling the shotcrete to be tested; the bottom surface of the test plate can be attached to the surface of the shotcrete to be tested filled in the chamber.

[0009] The support frame is equipped with a pulley mechanism at its top; the test plate and the tension assembly are symmetrically arranged on both sides of the support frame and are both located below the pulley mechanism; one end of the pull rope assembly is fixed to the top surface of the test plate, and the other end passes through the pulley mechanism and is fixed to the tension assembly; the tension assembly provides tension to the test plate through the pull rope assembly to measure the adhesion force between the test plate and the shotcrete to be tested filled in the mold.

[0010] As can be seen from the above technical solution, compared with the prior art, the sprayed concrete adhesion force testing device disclosed in this invention can fill the sprayed concrete to be tested into the slot at the top of the mold, and the filling amount of sprayed concrete is controllable; when the bottom surface of the test plate adheres to the surface of the sprayed concrete to be tested, it can play a covering role, avoiding the increase of measurement error due to evaporation and water loss of the sprayed concrete to be tested during long-term testing; the pulley mechanism is used to change the direction of the tension, so that the arrangement of the tension component is more flexible and conducive to the simplification of the structural form; this invention can complete the evaluation test of the bonding performance of concrete and surrounding rock in the plastic state in the laboratory, and has the characteristics of simple device structure and quick test operation.

[0011] As a further improvement to the above technical solution, the pull rope assembly includes guide pull ropes and fixed pull ropes; there are three or more fixed pull ropes, one end of each of the three or more fixed pull ropes is fixed to one end of the guide pull rope; the other end of each of the three or more fixed pull ropes is fixed to the top surface of the test plate and forms fixed points that are spaced apart from each other; when the three or more fixed pull ropes are tensioned, they form a conical structure; the other end of the guide pull rope passes through the pulley mechanism and is fixed to the tension assembly.

[0012] Three or more fixed pull ropes in a conical structure can ensure that the test plate is subjected to a stable and uniform tension, which can improve the reliability of the measurement.

[0013] As a further improvement to the above technical solution, the pulley mechanism includes two fixed pulleys; a crossbar is fixed on the top of the support frame along the opposite direction of the test plate and the tension component; one end of the crossbar is located above the test plate and the other end is located above the tension component; the two fixed pulleys are respectively fixed at both ends of the crossbar; the middle part of the guide rope passes around and rests in the groove of the two fixed pulleys to change the direction of the rope.

[0014] The crossbar serves to keep the test plate and tension components away from each other so they do not interfere with each other; the purpose of setting two fixed pulleys is to change the direction of the tension in the rope, which facilitates the spatial arrangement of the mold, test plate, support frame and tension components, thus achieving a simplified structure.

[0015] As a further improvement to the above technical solution, the tension component includes a bucket and fine sand. The bucket is suspended from the end of the guide rope. The fine sand can be added to the bucket to increase the tension of the bucket on the guide rope, thereby measuring the adhesion force between the test plate and the shotcrete to be tested filled in the mold.

[0016] By using a bucket and fine sand as counterweights to measure the pulling force, the structure is simple and the measurement accuracy is high. By adding fine sand, the pulling force can be continuously increased, thus improving the control accuracy of the pulling force.

[0017] As a further improvement to the above technical solution, the outer contour of the bottom surface of the test board is any one of square, circle, or polygon.

[0018] As a further improvement to the above technical solution, the test plate is a rock sheet with grooves or ridges on its bottom surface to simulate the actual rock surface roughness of the tunnel.

[0019] The grooves or ridges on the bottom of the test plate can simulate the roughness of the actual rock surface of the tunnel to a certain extent, thus improving the reliability of the test results.

[0020] Another aspect of the present invention provides a method for testing the adhesion of sprayed concrete, comprising the aforementioned sprayed concrete adhesion testing device, including the following steps:

[0021] S1: Fill the mold with freshly mixed shotcrete to be tested at once, and place the mold on a vibrating table to vibrate for 3 to 5 seconds;

[0022] S2: Smooth the surface of the shotcrete to be tested with a trowel and place the test mold on a horizontal surface;

[0023] S3: Place the bottom of the test board against the surface of the shotcrete to be tested, and gently tap the test board to ensure that its bottom surface is completely adhered to the surface of the shotcrete to be tested.

[0024] S4: Fix one end of the pull rope assembly to the top surface of the test plate, and fix the other end of the pull rope assembly through the pulley mechanism to the tension assembly.

[0025] S5: Gradually increase the tension of the tension component on the pull rope component until the test plate separates from the shotcrete to be tested. Record the force value of the tension component at this time, and the adhesion force between the shotcrete to be tested and the test plate can be calculated.

[0026] As a further improvement to the above technical solution, the pull rope assembly includes guide pull ropes and fixed pull ropes; there are three or more fixed pull ropes, one end of each of the three or more fixed pull ropes is fixed to one end of the guide pull rope; the other end of the three or more fixed pull ropes is fixed to the top surface of the test plate and forms correspondingly spaced fixed points; the three or more fixed pull ropes form a conical structure when tensioned; the other end of the guide pull rope passes through the pulley mechanism and is fixed to the tension assembly.

[0027] S4 specifically includes:

[0028] S41: Fix one end of each of the three or more fixed pull ropes to the same position as one end of the guide pull rope; cut the other end of the three or more fixed pull ropes to ensure that the three or more fixed pull ropes are of the same length.

[0029] S42: Arrange the other ends of three or more fixed pull ropes and the fixing points of the test board near the edge of the test board, and ensure that the three or more fixed pull ropes can be tensioned simultaneously to form a conical structure, with the cone apex of the conical structure corresponding to the upper middle part of the test board; adjust the position of the support frame so that the end of the guide pull rope close to the fixed pull rope is perpendicular to the surface of the test board.

[0030] As a further improvement to the above technical solution, the tensioning component includes a bucket and fine sand, the bucket being suspended from the end of the guide rope, and the fine sand being added to the bucket.

[0031] S5 specifically includes:

[0032] S51: Suspend the bucket at the end of the guide rope and keep the bucket stationary and undisturbed; at this time, the end of the guide rope near the bucket is in a vertically taut state.

[0033] S52: Slowly add fine sand to the bucket until the test plate separates from the shotcrete to be tested, and record the mass of the fine sand added at this time; the adhesion force between the shotcrete to be tested and the test plate can be calculated by the mass of the added fine sand, the mass of the bucket and the mass of the test plate.

[0034] As a further improvement to the above technical solution, step S6 is also included: measuring the adhesion force between the test plate and the sprayed concrete to be tested under inclined conditions to simulate the inclined state of the actual rock surface of the tunnel. The specific steps are as follows:

[0035] S61: Repeat the aforementioned steps S1, S2, and S3;

[0036] S62: Place a pad on one side of the bottom of the test mold to raise it, use a level to measure the tilt angle between the top surface of the test plate and the horizontal plane, and obtain the required tilt angle value by changing the pads of different heights or adjusting the position of the pads, and record the tilt angle value.

[0037] S63: Adjust the position of the support frame so that the end of the guide rope close to the fixed rope is perpendicular to the test plate surface; keep the bucket stationary; slowly add fine sand to the bucket until the test plate separates from the shotcrete to be tested, and record the mass of the fine sand added at this time; the adhesion force between the test plate and the shotcrete to be tested in the tilted state can be calculated by the mass of the added fine sand, the mass of the bucket and the mass of the test plate.

[0038] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a sprayed concrete adhesion testing device, which has the following advantages and beneficial effects:

[0039] 1. The present invention fills the top chamber of the test mold with the shotcrete to be tested, and the test plate covers the surface of the shotcrete to be tested, which can ensure the stability of the properties of the shotcrete to be tested and improve the measurement accuracy.

[0040] 2. The test plate of this invention uses rock sheets and has grooves and ridges on the measuring surface, which simulates the roughness of the actual rock surface of the tunnel to a certain extent, allowing the shotcrete to fully contact the rock sheets and improving the accuracy of the test results.

[0041] 3. The test mold of this invention can be placed horizontally or tilted, and is suitable for pull-out measurement in both horizontal and tilted states. The tilt angle adjustment in the tilted state is also convenient. Lightweight pull ropes can be used to transmit the tension. By controlling the length of the pull rope and the fixing point, the direction of the tension can be ensured to be perpendicular to the test plate, which reduces the systematic error of the device and improves the measurement accuracy.

[0042] 4. This invention allows for the simulation and evaluation of the bonding performance between sprayed concrete and surrounding rock in the laboratory by adjusting parameters such as concrete mix ratio and rock lithology according to the actual conditions of the construction site. The testing steps are simple and the results are accurate. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0044] Figure 1 A schematic diagram of the overall structure of a shotcrete adhesion force testing device according to the present invention;

[0045] Figure 2 A schematic diagram of the groove on the bottom surface of the test plate of a shotcrete adhesion testing device according to the present invention;

[0046] Figure 3 A schematic diagram of the ridge on the bottom surface of the test plate of a shotcrete adhesion testing device according to the present invention.

[0047] Figure 4 A schematic diagram of the coordinate lines on the top surface of the test plate of a shotcrete adhesion testing device according to the present invention;

[0048] In the diagram: 1. Trial mold; 11. Tank chamber; 2. Test plate; 21. Groove; 22. Ridge; 23. Coordinate line; 3. Support frame; 31. Pulley mechanism; 311. Fixed pulley; 32. Crossbar; 4. Pull rope assembly; 41. Guide pull rope; 42. Fixed pull rope; 43. Fixing point; 5. Tension assembly; 51. Bucket body; 52. Fine sand. Detailed Implementation

[0049] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0050] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] like Figures 1 to 4 As shown, a shotcrete adhesion testing device includes:

[0054] One aspect of the present invention provides a shotcrete adhesion testing device, comprising: a test mold 1, a test plate 2, a support frame 3, a rope assembly 4, and a tension assembly 5;

[0055] The test mold 1 is located on the side of the support frame 3, and has a top chamber 11 for filling the shotcrete to be tested; the bottom surface of the test plate 2 can be attached to the surface of the shotcrete to be tested filled in the chamber 11.

[0056] A pulley mechanism 31 is provided on the top of the support frame 3; the test plate 2 and the tension assembly 5 are symmetrically arranged on both sides of the support frame 3 and are both located below the pulley mechanism 31; one end of the rope assembly 4 is fixed to the top surface of the test plate 2, and the other end passes through the pulley mechanism 31 and is fixed to the tension assembly 5; the tension assembly 5 provides tension to the test plate 2 through the rope assembly 4 to measure the adhesion force between the test plate 2 and the shotcrete to be tested filled in the mold 1.

[0057] The shotcrete adhesion testing device of this embodiment can be filled with the shotcrete to be tested in the chamber 11 at the top of the mold 1, and the amount of shotcrete can be controlled. When the bottom surface of the test plate 2 is attached to the surface of the shotcrete to be tested, it can play a covering role, avoiding the increase of measurement error due to evaporation and water loss of the shotcrete to be tested during long-term testing. The pulley mechanism 31 is used to change the direction of the tension, so that the arrangement of the tension component 5 is more flexible and conducive to the simplification of the structure. This device can complete the evaluation test of the bonding performance between concrete and surrounding rock in the plastic state in the laboratory, and has the characteristics of simple device structure and quick test operation.

[0058] Specifically, mold 1 is made of cast iron and has a rectangular structure with a length, width, and height of 150mm, 250mm, and 50mm, respectively.

[0059] The support frame 3 is made of welded steel pipes. It is placed on the ground and can be moved. The total height of the support frame 3 is 650mm.

[0060] In some specific embodiments, the pull rope assembly 4 includes a guide pull rope 41 and fixed pull ropes 42; there are four fixed pull ropes 42, one end of each of the four fixed pull ropes 42 is tied to one end of the guide pull rope 41 or flattened and snapped together by a lightweight metal ring; the other end of each of the four fixed pull ropes 42 is fixed to the top surface of the test plate 2 and forms correspondingly spaced fixed points 43; the four fixed pull ropes 42 form a conical structure when tensioned; the other end of the guide pull rope 41 passes through the pulley mechanism 31 and is fixed to the tension assembly 5.

[0061] The four fixed pull ropes 42 have a conical structure, which ensures that the test plate 2 is subjected to a stable and uniform tension, thus improving the reliability of the measurement.

[0062] Specifically, both the guide rope 41 and the fixing rope 42 are nylon ropes or thin steel wire ropes.

[0063] In some specific embodiments, the pulley mechanism 31 includes two fixed pulleys 311; a crossbar 32 is welded and fixed to the top of the support frame 3 along the opposite direction of the test plate 2 and the tension component 5; one end of the crossbar 32 is located above the test plate 2 and the other end is located above the tension component 5; the two fixed pulleys 311 are welded and fixed to the two ends of the crossbar 32 respectively; the guide rope 41 passes around the middle of the two fixed pulleys 311 and is placed in the groove of the two fixed pulleys 311 to change the direction of the rope.

[0064] The function of the crossbar 32 is to facilitate the arrangement of the test plate 2 and the tension component 5 far apart so that they do not interfere with each other; the purpose of setting two fixed pulleys 311 is to change the direction of the tension of the pull rope, which is conducive to the spatial arrangement of the test mold 1, the test plate 2, the support frame 3 and the tension component 5, and achieves the effect of structural simplification.

[0065] Specifically, the two fixed pulleys 311 are both 30mm in diameter; the rotation axes of the two fixed pulleys 311 are both horizontally arranged and parallel to each other; the rotation axes of the two fixed pulleys 311 are perpendicular to the crossbar 32.

[0066] In some specific embodiments, the tension component 5 includes a barrel 51 and fine sand 52. The barrel 51 is suspended at the end of the guide rope 41. The fine sand 52 can be added to the barrel 51 to increase the tension of the barrel 51 on the guide rope 41, thereby measuring the adhesion force between the test plate 2 and the shotcrete to be tested filled in the mold 1.

[0067] By using the barrel 51 and fine sand 52 as counterweights to measure the pulling force, the structure is simple and the measurement accuracy is high. By adding fine sand 52, the pulling force can be continuously increased, thus improving the control accuracy of the pulling force.

[0068] Specifically, the barrel body 51 is made of stainless steel, with a diameter of 250mm and a height of 300mm.

[0069] In some specific embodiments, the outer contour of the bottom surface of the test board 2 is any one of square, circle, or polygon.

[0070] In some specific embodiments, the bottom surface of the test plate 2 can be any one of a plane, a regular uneven rough surface, or an irregular uneven rough surface.

[0071] Specifically, the outer contour of the bottom surface of test board 2 is a regular shape, which facilitates the calculation of the equivalent area of ​​the bottom surface. The equivalent area refers to the projected area of ​​the bottom surface along the direction perpendicular to the surface of test board 2.

[0072] In some specific embodiments, the test plate 2 is a thin rock sheet with grooves 21 or ridges 22 on its bottom surface to simulate the actual rock surface roughness of the tunnel.

[0073] The grooves 21 or ridges 22 on the bottom surface of the test plate 2 can simulate the roughness of the actual rock surface of the tunnel to a certain extent, thus improving the reliability of the test results.

[0074] Specifically, the test plate 2 is made of granite, with a length, width, and height of 100mm, 100mm, and 20mm, respectively. A grooving machine is used to groove the top surface of the test plate 2 to form multiple grooves 21, each groove 21 having a width of 5mm, a depth of 2mm, and a spacing of 8mm between adjacent grooves. Alternatively, a grooving machine can be used to groove the top surface of the test plate 2 to form multiple ridges 22, each ridge 22 having a width of 5mm, a height of 2mm, and a spacing of 8mm between adjacent ridges 22.

[0075] Specifically, the top surface of the test board 2 is fixed with four fixing ropes 42 by epoxy resin. The four fixing points 43 are arranged at the four corners of the test board 2, and the vertical distance between the four fixing points 43 and the corresponding edge of the test board 2 is 15mm.

[0076] In some specific embodiments, the top surface of the test plate 2 is a plane and is marked with coordinate lines 23 that facilitate accurate positioning of the fixed point 43.

[0077] In some specific embodiments, a laser is fixedly installed at the center of the top surface of the test plate 2. The laser beam of the laser is emitted vertically upwards from the top surface of the test plate 2. During the test, it can be used to calibrate the perpendicularity of the guide rope 41 near the fixed rope 42 to the top surface of the test plate 2, ensuring that the direction of the tension is perpendicular to the top surface of the test plate 2, thereby improving the test accuracy.

[0078] An embodiment of the present invention provides a method for testing the adhesion force of sprayed concrete, comprising the aforementioned sprayed concrete adhesion force testing device, and including the following steps:

[0079] S1: Fill the mold 1 with freshly mixed shotcrete to be tested in one go, and place the mold 1 on the vibrating table and vibrate for 3 to 5 seconds.

[0080] S2: Smooth the surface of the shotcrete to be tested with a trowel, and place the test mold 1 on a horizontal surface;

[0081] S3: Place the bottom surface of the test plate 2 against the surface of the sprayed concrete to be tested, and gently tap the test plate 2 to ensure that its bottom surface is completely adhered to the surface of the sprayed concrete to be tested.

[0082] S4: One end of the pull rope assembly 4 is fixedly connected to the top surface of the test plate 2, and the other end of the pull rope assembly 4 passes through the pulley mechanism 31 and is fixedly connected to the tension assembly 5.

[0083] S5: Gradually increase the tension of the tension component 5 on the pull rope component 4 until the test plate 2 separates from the shotcrete to be tested. Record the force value of the tension component 5 at this time, and the adhesion force between the shotcrete to be tested and the test plate 2 can be calculated.

[0084] In some specific embodiments, S4 specifically includes:

[0085] S41: Fix one end of each of the three or more fixed pull ropes 42 to the same position point as one end of the guide pull rope 41; cut the other end of the three or more fixed pull ropes 42 to ensure that the three or more fixed pull ropes 42 are of the same length.

[0086] S42: Arrange the other end of three or more fixed pull ropes 42 and the fixing point 43 of the test plate 2 near the edge of the test plate 2, and ensure that the three or more fixed pull ropes 42 can be tensioned at the same time to form a conical structure, with the cone apex of the conical structure corresponding to the center point directly above the test plate 2; adjust the position of the support frame 3 so that the end of the guide pull rope 41 close to the fixed pull rope 42 is perpendicular to the surface of the test plate 2.

[0087] In some specific embodiments, S5 specifically includes:

[0088] S51: Suspend the barrel 51 at the end of the guide rope 41 and keep the barrel 51 stationary and undisturbed; at this time, the end of the guide rope 41 near the barrel 51 is in a vertically taut state.

[0089] S52: Slowly add fine sand 52 to the barrel 51 until the test plate 2 separates from the shotcrete to be tested, and record the mass of the fine sand 52 added at this time; the adhesion force between the shotcrete to be tested and the test plate 2 can be calculated by the mass of the added fine sand 52, the mass of the barrel 51 and the mass of the test plate 2.

[0090] In some specific embodiments, step S6 is also included, measuring the adhesion force between the test plate 2 and the shotcrete to be tested in an inclined state to simulate the inclined state of the actual rock surface of the tunnel. The specific steps are as follows:

[0091] S61: Repeat the aforementioned steps S1, S2, and S3;

[0092] S62: Place a pad on one side of the bottom of the test mold 1 to raise it, use a level to measure the tilt angle between the top surface of the test plate 2 and the horizontal plane, and obtain the required tilt angle value by changing the pads of different heights or adjusting the position of the pads, and record the tilt angle value.

[0093] S63: Adjust the position of the support frame 3 so that the end of the guide rope 41 close to the fixed rope 42 is perpendicular to the surface of the test plate 2; keep the bucket 51 stationary; slowly add fine sand 52 to the bucket 51 until the test plate 2 separates from the shotcrete to be tested, and record the mass of the fine sand 52 added at this time; the adhesion force between the test plate 2 and the shotcrete to be tested in the tilted state can be calculated by the mass of the added fine sand 52, the mass of the bucket 51 and the mass of the test plate 2.

[0094] Specifically, after the test, the total mass of the bucket 51 and fine sand 52 is recorded as m, the mass of the test plate 2 is n, and the mass difference between the total mass of the bucket 51 and fine sand 52 and the mass of the test plate 2 is M = mn; the adhesion force between the test plate 2 and the sprayed concrete to be tested is Mg, and the gravitational acceleration g can be approximated as 10, so the adhesion force is 10M.

[0095] Example: In a certain experiment, the shotcrete mix proportions are shown in Table 1. The test records show that the mass of fine sand 52 was 3.5 kg, the mass of the bucket 51 was 0.6 kg, and the mass of the test plate 2 was 2.4 kg. Based on the calculation method proposed in this invention, the adhesion force value is 17 N, and the bottom area of ​​the test plate 2 is 0.01 m². 2 The adhesion pressure value is 1700 N / m. 2 .

[0096] Table 1 Shotcrete mix proportions (unit: kg / m³) 3 )

[0097] cement river sand 5-10mm gravel Water reducing agent water 470 820 820 4.7 182

[0098] Note: The slump of the concrete leaving the mixer is 180-200 mm, and the air content is 3-4%.

[0099] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for testing the adhesion force of sprayed concrete, comprising a sprayed concrete adhesion force testing device, characterized in that, The device includes: a test mold (1), a test plate (2), a support frame (3), a rope assembly (4), and a tension assembly (5); The test mold (1) is located on the side of the support frame (3) and has a top chamber (11) for filling the shotcrete to be tested; the bottom surface of the test plate (2) can adhere to the surface of the shotcrete to be tested filled in the chamber (11); The support frame (3) is provided with a pulley mechanism (31) at the top; the test plate (2) and the tension assembly (5) are symmetrically arranged on both sides of the support frame (3) and are both located below the pulley mechanism (31); one end of the pull rope assembly (4) is fixed to the top surface of the test plate (2), and the other end passes through the pulley mechanism (31) and is fixed to the tension assembly (5); the tension assembly (5) provides tension to the test plate (2) through the pull rope assembly (4) to measure the adhesion force between the test plate (2) and the shotcrete to be tested filled in the mold (1); The pull rope assembly (4) includes a guide pull rope (41) and a fixed pull rope (42); there are three or more fixed pull ropes (42), one end of each of the three or more fixed pull ropes (42) is fixed to one end of the guide pull rope (41); the other end of each of the three or more fixed pull ropes (42) is fixed to the top surface of the test plate (2) and forms fixed points (43) that are spaced apart from each other; when the three or more fixed pull ropes (42) are tensioned, they form a conical structure; the other end of the guide pull rope (41) passes through the pulley mechanism (31) and is fixed to the tension assembly (5); The tension component (5) includes a barrel (51) and fine sand (52). The barrel (51) is suspended at the end of the guide rope (41). The fine sand (52) can be added to the barrel (51) to increase the tension of the barrel (51) on the guide rope (41), thereby measuring the adhesion force between the test plate (2) and the shotcrete to be tested filled in the mold (1). The method includes the following steps: S1: Fill the test mold (1) with freshly mixed sprayed concrete in one go, and place the test mold (1) on the vibration table and vibrate for 3~5s; S2: Smooth the surface of the shotcrete to be tested with a trowel, and place the test mold (1) on a horizontal ground; S3: Place the bottom surface of the test plate (2) against the surface of the sprayed concrete to be tested, and gently tap the test plate (2) to ensure that its bottom surface is completely adhered to the surface of the sprayed concrete to be tested. S4: Fix one end of the pull rope assembly (4) to the top surface of the test plate (2), and fix the other end of the pull rope assembly (4) through the pulley mechanism (31) to the tension assembly (5); S5: Gradually increase the tension of the tension component (5) on the rope component (4) until the test plate (2) separates from the shotcrete to be tested. Record the force value of the tension component (5) at this time, so that the adhesion force between the shotcrete to be tested and the test plate (2) can be calculated. S6: Measure the adhesion force between the test plate (2) and the sprayed concrete to be tested under inclined conditions to simulate the inclined state of the actual rock surface of the tunnel. The specific steps are as follows: S61: Repeat the aforementioned steps S1, S2, and S3; S62: Place a pad on one side of the bottom of the test mold (1) to raise it, use a level to measure the tilt angle between the top surface of the test plate (2) and the horizontal plane, and obtain the required tilt angle value by changing the pads of different heights or adjusting the position of the pads, and record the tilt angle value. S63: Adjust the position of the support frame (3) so that the end of the guide rope (41) close to the fixed rope (42) is perpendicular to the test plate (2); keep the bucket (51) stationary; slowly add fine sand (52) to the bucket (51) until the test plate (2) separates from the shotcrete to be tested, and record the mass of the fine sand (52) added at this time; the adhesion force between the test plate (2) and the shotcrete to be tested in the tilted state can be calculated by the mass of the added fine sand (52), the mass of the bucket (51) and the mass of the test plate (2).

2. The method for testing the adhesion of sprayed concrete according to claim 1, characterized in that, The pulley mechanism (31) includes two fixed pulleys (311); a crossbar (32) is fixed on the top of the support frame (3) along the opposite direction of the test plate (2) and the tension assembly (5); one end of the crossbar (32) is located above the test plate (2), and the other end is located above the tension assembly (5); the two fixed pulleys (311) are respectively fixed at both ends of the crossbar (32); the guide rope (41) passes around and is placed in the groove of the two fixed pulleys (311) in sequence to change the direction of the rope.

3. The method for testing the adhesion of sprayed concrete according to claim 2, characterized in that, The outer contour of the bottom surface of the test board (2) can be any one of square, circle, or polygon.

4. The method for testing the adhesion of sprayed concrete according to claim 2, characterized in that, The test plate (2) is a rock sheet with grooves (21) or ridges (22) on its bottom surface to simulate the actual rock surface roughness of the tunnel.

5. The method for testing the adhesion of sprayed concrete according to claim 1, characterized in that, S4 specifically includes: S41: Fix one end of three or more fixed pull ropes (42) to one end of the guide pull rope (41) at the same position point; cut the other end of three or more fixed pull ropes (42) to ensure that the three or more fixed pull ropes (42) are the same length; S42: Arrange the other end of three or more fixed pull ropes (42) and the fixed point (43) of the test plate (2) near the edge of the test plate (2), and ensure that the three or more fixed pull ropes (42) are all tensioned at the same time to form a conical structure, the cone apex of the conical structure corresponds to the upper middle part of the test plate (2); adjust the position of the support frame (3) so that the end of the guide pull rope (41) near the fixed pull rope (42) is perpendicular to the surface of the test plate (2).

6. The method for testing the adhesion force of sprayed concrete according to claim 5, characterized in that, S5 specifically includes: S51: Suspend the bucket (51) at the end of the guide rope (41) and keep the bucket (51) stationary and undisturbed; at this time, the end of the guide rope (41) near the bucket (51) is in a vertically taut state. S52: Slowly add fine sand (52) to the bucket (51) until the test plate (2) separates from the shotcrete to be tested, and record the mass of the fine sand (52) added at this time; the adhesion force between the shotcrete to be tested and the test plate (2) can be calculated by the mass of the fine sand (52), the mass of the bucket (51) and the mass of the test plate (2).

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