Novel shotcrete and surrounding rock bonding strength testing device

Abstract

The utility model discloses a novel shotcrete and surrounding rock bonding strength testing device which comprises a square plate, a through hole is formed in the center of the square plate, an expansion screw is sleeved with the through hole, a plurality of connecting holes are formed in the corners of the periphery of the square plate, a leveling nut is coaxially welded to the side, close to shotcrete, of each connecting hole, and a connecting screw rod is arranged in each connecting hole. The connecting screw penetrates through the leveling nut and then is sleeved with the connecting nut, the square plate is arranged on the sprayed concrete through the connecting screw, one end of the expansion screw penetrates through the square plate and is inserted into the sprayed concrete, and the expansion screw is connected with the anchor rod drawing instrument. According to the utility model, the problems of inaccurate test result and difficulty in operation of the test device of the existing core drilling and drawing method are solved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to civil engineering technical field relates to a new type of shotcrete and surrounding rock bonding strength testing device. BACKGROUND

[0002] Shotcrete and surrounding rock bonding strength detection is an important means of shotcrete quality detection. The detection method of shotcrete and surrounding rock bonding strength can be mainly divided into three kinds: reserved specimen pull-out method, core drilling pull-out method and splitting method detection.

[0003] Using the reserved specimen pull-out method, the test is carried out on the construction site, the shotcrete thickness of the test site should be more than 100mm, and the surrounding rock surface is relatively flat, the steel pull rod needs to be pre-buried in the center position of the specimen, the pull-out force of which should be greater than the bonding force of shotcrete and surrounding rock, after the concrete of the specimen site is sprayed, immediately use a shovel to dig out a groove with a width of about 50mm along the specimen contour, so that the specimen is completely separated from the surrounding sprayed concrete, only the bottom surface is bonded with the surrounding rock, after the shotcrete reaches the design strength, the pull rod is pulled by the puller, so that the specimen is damaged along the bonding surface with the surrounding rock. The reserved specimen pull-out method is not representative, and the construction unit tends to bury the specimen in the area with good rock integrity and clean rock surface, which reduces the representativeness of the test to some extent. The reserved specimen pull-out method needs to be grooved immediately after the shotcrete construction is completed, otherwise it may be difficult to groove and disturb the pre-buried specimen. The pre-buried specimen is easily damaged by construction machinery, which leads to test failure.

[0004] Using the splitting method for detection, place the rock plate with a thickness of more than 50mm selected from the construction site in the wooden mold (450×350×12mm) of the shotcrete plate, wet the surface of the rock plate with water, and spray the concrete into the plate mold according to the actual spraying conditions. After 7d of curing under the same conditions as the actual structure, cut the specimen into a cube with a side of 100mm (the thickness of rock and concrete is about 50mm respectively), and cure to 28d age. At the bonding surface between the concrete and the rock block, the bonding strength value of the concrete and the rock block is measured by the splitting method. The specimen for splitting method must be formed on site. It is found that the test results are related to the shape, cleanliness and mechanical properties of the selected stone, and cannot accurately reflect the actual situation on site.

[0005] Therefore, the core drilling and pulling method is commonly used to detect the bonding strength of the sprayed concrete and the surrounding rock. When the core drilling and pulling method is used to detect the bonding strength of the sprayed concrete and the surrounding rock on site, a small drilling machine is used to drill into the sprayed concrete layer and penetrate into the surrounding rock by more than 20mm to form a cylindrical core sample with the bonding surface of the sprayed concrete and the surrounding rock, a sleeve is used to cover and tightly hold the core sample, a pulling device is installed, a pulling force is slowly applied to the sleeve until the core sample is damaged along the bonding surface of the sprayed concrete and the surrounding rock. The test device is difficult to core, the test cost is high, the overall operation is relatively complex, the sleeve needs to be customized without production standards, expensive equipment and professional technicians are needed, the engineering cost is increased, the test results are uneven, and the test results cannot truly reflect the bonding of the sprayed concrete and the surrounding rock. Content of the utility model

[0006] The utility model discloses a novel sprayed concrete and surrounding rock bonding strength test device, and solves the problem that the test device of the prior core drilling and pulling method is inaccurate and difficult to operate.

[0007] The utility model discloses a novel sprayed concrete and surrounding rock bonding strength test device, and solves the problem that the test device of the prior core drilling and pulling method is inaccurate and difficult to operate.

[0008] The utility model discloses a novel sprayed concrete and surrounding rock bonding strength test device, and solves the problem that the test device of the prior core drilling and pulling method is inaccurate and difficult to operate.

[0009] The utility model discloses a novel sprayed concrete and surrounding rock bonding strength test device, and solves the problem that the test device of the prior core drilling and pulling method is inaccurate and difficult to operate.

[0010] The utility model discloses a novel sprayed concrete and surrounding rock bonding strength test device, and solves the problem that the test device of the prior core drilling and pulling method is inaccurate and difficult to operate.

[0011] The square plate adopts a 200mm*200mm*10mm long square steel plate, a through hole with a diameter of 40mm is arranged at the center of the square plate, the connecting holes are arranged at the center points of every two sides with a distance of 35mm, the internal thread diameter of the connecting holes is 10mm, the pitch is 1.5mm, and there are four connecting holes in total.

[0012] The connecting screw in the connecting hole is 100mm long and 10mm in diameter, the connecting nut adopts a hexagonal flange surface toothed nut, the size is 10mm, the thickness is 8.8mm, the opposite side is 14mm, the flange diameter is 19mm; the leveling nut adopts a hexagonal flat flange nut, the size is 10mm, the flange diameter is 22mm, the flange thickness is 2.5mm, the opposite side is 17mm, the nut height is 14.5mm, and the flange surface faces the square plate and is perpendicular to the connecting hole; the connecting screw is screwed into the back of the hexagonal flat flange nut welded to the square plate, the end of the connecting screw is connected with the hexagonal flange surface toothed nut, the toothed flange surface faces the shotcrete surface, and leveling of the square plate is performed after being fixed.

[0013] The screw rod in the expansion screw is 10mm in diameter and 150mm in length, and is made of Q235 round steel material.

[0014] The novel shotcrete and surrounding rock bonding strength test device has the advantages that the square plate is leveled, the expansion screw in the jack is in vertical contact with the shotcrete, the stability is improved, the test result is accurate, the test detection efficiency is improved, all tools and materials can be recycled and used again, the loss of test detection tools and materials is reduced, the selected detection point has randomness, the construction efficiency is improved, and the construction experiment demand is met. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structural schematic view of the novel shotcrete and surrounding rock bonding strength test device.

[0016] In the figure, 1 is surrounding rock, 2 is shotcrete, 3 is an oil pump, 4 is a square plate, 5 is an anchor rod pullout tester, 6 is a connecting nut, 7 is an expansion screw, 8 is a hot-rolled ribbed steel bar, and 9 is an anchor clamp. DETAILED DESCRIPTION

[0017] The novel shotcrete and surrounding rock bonding strength test device will be described in detail in combination with the drawings and specific embodiments.

[0018] Embodiment 1

[0019] The novel shotcrete and surrounding rock bonding strength test device has the advantages that the square plate is leveled, the expansion screw in the jack is in vertical contact with the shotcrete, the stability is improved, the test result is accurate, the test detection efficiency is improved, all tools and materials can be recycled and used again, the loss of test detection tools and materials is reduced, the selected detection point has randomness, the construction efficiency is improved, and the construction experiment demand is met. Figure 1As shown, it comprises a square plate 4, a through hole is formed at the center of the square plate 4, an expansion screw 7 is sleeved in the through hole, a plurality of connecting holes are arranged at the four corners of the square plate 4, a leveling nut is coaxially welded on one side of each connecting hole close to the sprayed concrete 2, a connecting screw rod is arranged in the connecting hole, the connecting screw rod is sleeved with a connecting nut 6 after penetrating through the leveling nut, the square plate 4 is arranged on the sprayed concrete 2 through the connecting screw rod, one end of the expansion screw 7 penetrates through the square plate 4 and is inserted into the sprayed concrete 2, and the expansion screw 7 is connected with the anchor rod pullout apparatus 5.

[0020] Embodiment 2

[0021] The utility model relates to a novel sprayed concrete and surrounding rock bonding strength test device, like Figure 1 As shown, it comprises a square plate 4, a through hole is formed at the center of the square plate 4, an expansion screw 7 is sleeved in the through hole, a plurality of connecting holes are arranged at the four corners of the square plate 4, a leveling nut is coaxially welded on one side of each connecting hole close to the sprayed concrete 2, a connecting screw rod is arranged in the connecting hole, the connecting screw rod is sleeved with a connecting nut 6 after penetrating through the leveling nut, the square plate 4 is arranged on the sprayed concrete 2 through the connecting screw rod, one end of the expansion screw 7 penetrates through the square plate 4 and is inserted into the sprayed concrete 2, and the expansion screw 7 is connected with the anchor rod pullout apparatus 5.

[0022] On the basis of embodiment 1, the anchor rod pullout apparatus 5 comprises a hollow hydraulic jack, the inside of the hollow hydraulic jack is composed of a piston, a sealing ring, a hollow plunger and a cylinder body, the expansion screw 7 is installed in the hollow part of the hollow hydraulic jack, the other end of the expansion screw 7 is connected with a hot-rolled ribbed steel bar 8, the hot-rolled ribbed steel bar 8 is sleeved with the part connected with the expansion screw 7 and penetrates through the hollow hydraulic jack, the hollow hydraulic jack is connected with the oil pump 3 through a high-pressure oil pipe, and the part of the hot-rolled ribbed steel bar 8 that extends out of the hollow hydraulic jack is provided with an anchor clamp 9.

[0023] The expansion screw 7 comprises a screw rod, an expansion pipe, a flat washer, a spring washer and a hexagonal nut are sequentially sleeved on the threaded end of the screw rod, and a hexagonal conical head is arranged on the threaded end of the screw rod. The diameter of the hot-rolled ribbed steel bar 8 is 25mm, and the length is 450mm. A screw thread is formed in the end of the hot-rolled ribbed steel bar 8, the diameter of the screw thread is 10mm, and the length of the screw thread is 30mm. The screw thread at the end of the hot-rolled ribbed steel bar 8 is connected with the expansion pipe on the screw rod.

[0024] Embodiment 3

[0025] The utility model relates to a novel sprayed concrete and surrounding rock bonding strength test device, like Figure 1As shown, it includes a square plate 4, a through hole is opened at the center of the square plate 4, an expansion screw 7 is sleeved in the through hole, a number of connecting holes are set at the corners of the four sides of the square plate 4, each connecting hole is coaxially welded with a leveling nut close to the side of the shotcrete 2, a connecting screw is set in the connecting hole, the connecting screw passes through the leveling nut and then sleeved with the connecting nut 6, the square plate 4 is set on the shotcrete 2 through the connecting screw, one end of the expansion screw 7 passes through the square plate 4 and is inserted into the shotcrete 2, and the expansion screw 7 is connected to the anchor puller 5.

[0026] The anchor puller 5 includes a hollow hydraulic jack, the interior of which is composed of a piston, a sealing ring, a hollow plunger and a cylinder body. An expansion screw 7 is installed in the hollow part of the hollow hydraulic jack, and the other end of the expansion screw 7 is connected to the hot-rolled ribbed steel bar 8. The part of the hot-rolled ribbed steel bar 8 connected to the expansion screw 7 is sleeved through the hollow hydraulic jack. The hollow hydraulic jack is connected to the oil pump 3 through a high-pressure oil pipe, and the part of the hot-rolled ribbed steel bar 8 extending outside the hollow hydraulic jack is provided with an anchor clamp 9.

[0027] The expansion screw 7 consists of a screw rod, the threaded end of which is fitted with an expansion tube, a flat washer, a spring washer, and a hexagonal nut. The threaded end of the screw rod features a hexagonal conical head. The hot-rolled ribbed steel bar 8 has a diameter of 25 mm and a length of 450 mm. The end of the hot-rolled ribbed steel bar 8 has an inward threaded connection with a thread diameter of 10 mm and a thread length of 30 mm. The end of the hot-rolled ribbed steel bar 8 is threadedly connected to the expansion tube on the screw rod.

[0028] Based on Example 2, the square plate 4 is a 200mm×200mm×10mm square steel plate. The through hole at the center of the square plate 4 has a diameter of 40mm. The square plate 4 has connecting holes centered at 35mm on each side. The inner thread of the connecting hole has a diameter of 10mm and a pitch of 1.5mm, with one hole on each side, for a total of four connecting holes. The connecting screw in the connecting hole is 100mm long and 10mm in diameter. The connecting nut 6 is a hexagonal flange toothed nut with a size of 10mm and a thickness of 8. 8mm, opposite side 14mm, flange diameter 19mm; the leveling nut adopts a hexagonal flat flange nut, size 10mm, flange diameter 22mm, flange thickness 2.5mm, opposite side 17mm, nut height 14.5mm, the flange surface faces the direction of square plate 4, perpendicular to the connecting hole; the connecting screw is screwed into the back of the hexagonal flat flange nut welded to the square plate 4, and the end of the connecting screw is connected to the toothed nut on the hexagonal flange surface, with the toothed flange surface facing the two sides of the shotcrete. After fixing, the square plate 4 is leveled.

[0029] The diameter of the screw in the expansion screw 7 is 10 mm and the length is 150 mm. The screw is made of Q235 round steel.

[0030] The working principle of the novel shotcrete and surrounding rock bonding strength test device is that when the jack in the anchor rod pull-out tester 5 pulls, force is transmitted to the hot-rolled ribbed steel bar 8, the hot-rolled ribbed steel bar 8 further applies force to the expansion screw 7, and finally the expansion screw 7 applies force to the shotcrete 2; when the shotcrete 2 support surface is uneven, the connecting screw rod and the connecting nut and the leveling nut on the square plate 4 are used in cooperation, so that the shotcrete 2 support surface is a plane, the deviation between the central axis of the jack and the axis of the expansion screw 7 is reduced, so that the expansion screw 7 and the square plate 4 are kept vertical, and the measurement error caused by the uneven support surface is reduced.

[0031] The working process of the novel shotcrete and surrounding rock bonding strength test device is that after the shotcrete 2 to be sprayed reaches the design age, on the randomly selected test point, first, a handheld electric drill with a 14mm diameter drill bit is used to drill a hole perpendicular to the shotcrete layer, the expansion screw 7 is installed, and the drill bit is tightened with a wrench, then a portable diamond drill with a drill bit diameter of 100mm is used to drill a core with the expansion screw 7 as the center point, and the drill bit is perpendicular to the shotcrete 2 layer and penetrates into the surrounding rock 1 by more than 20mm, forming a cylindrical core sample with a shotcrete 2 and surrounding rock 1 bonding surface; secondly, attention should be paid to the drilling depth of the electric drill, which should not exceed the design thickness of the shotcrete 2, so as to prevent the expansion screw 7 from being installed into the surrounding rock 1; the end of the expansion screw 7 is tightly connected with the hot-rolled ribbed steel bar 8, the connecting screw rod passes through the leveling nut and then is sleeved with the connecting nut, the square plate 4 is leveled, and then is sequentially placed in the hollow part of the hollow hydraulic jack, and the whole is leveled, the anchor rod pull-out tester 5 is used for pulling, the test is carried out, and the peak pulling force is recorded.

[0032] The novel shotcrete and surrounding rock bonding strength test device has the advantages that the hollow hydraulic jack of the anchor rod pull-out tester 5 is used as a driving source to realize the function, without increasing energy consumption, the connecting screw rod and the connecting nut and the leveling nut on the square plate 4 are used in cooperation to reduce the manual operation of the operator, the problems of inaccurate test results and difficult operation of the existing core drilling and pulling test device are well solved, the device has the characteristics of simplicity, economy and practicality, the test device is more reliable and has a longer service life, at the same time, the test construction period is short, the on-site construction is efficient, and the comprehensive comparison is economical and reasonable.

Claims

1. A new type of test device for the bonding strength between shotcrete and surrounding rock, characterized in that: The invention comprises a square plate (4), a through hole is provided at the center of the square plate (4), an expansion screw (7) is sleeved in the through hole, a plurality of connection holes are provided at the four corners of the square plate (4), each connection hole is coaxially welded with a leveling nut close to one side of the sprayed concrete (2), a connecting screw is provided in the connection hole, the connecting screw passes through the leveling nut and then sleeved with the connecting nut (6), the square plate (4) is provided on the sprayed concrete (2) through the connecting screw, one end of the expansion screw (7) passes through the square plate (4) and is inserted into the sprayed concrete (2), and the expansion screw (7) is connected to the anchor rod puller (5).

2. A new type of sprayed concrete and surrounding rock bonding strength testing device according to claim 1, characterized in that: The anchor rod pulling instrument (5) includes a hollow hydraulic jack, the interior of the hollow hydraulic jack is composed of a piston, a sealing ring, a hollow plunger and a cylinder body, an expansion screw (7) is installed in the hollow part of the hollow hydraulic jack, the other end of the expansion screw (7) is connected to the hot-rolled ribbed steel bar (8), the part of the hot-rolled ribbed steel bar (8) connected to the expansion screw (7) is sleeved through the hollow hydraulic jack, the hollow hydraulic jack is connected to the oil pump (3) through a high-pressure oil pipe, and the part of the hot-rolled ribbed steel bar (8) extending outside the hollow hydraulic jack is provided with an anchor clamp (9).

3. A new type of sprayed concrete and surrounding rock bonding strength testing device according to claim 2, characterized in that: The expansion screw (7) comprises a screw rod, the threaded end of the screw rod is sequentially covered with an expansion tube, a flat washer, a spring washer and a hexagonal nut, and the threaded end of the screw rod adopts a hexagonal tapered head.

4. A new type of sprayed concrete and surrounding rock bonding strength testing device according to claim 3, characterized in that: The hot-rolled ribbed steel bar (8) has a diameter of 25 mm and a length of 450 mm. The end of the hot-rolled ribbed steel bar (8) is threaded inwardly, with a thread diameter of 10 mm and a thread length of 30 mm. The end of the hot-rolled ribbed steel bar (8) is threadedly connected to the expansion tube on the screw.

5. A new type of sprayed concrete and surrounding rock bonding strength testing device according to claim 1, characterized in that: The square plate (4) is a 200mm×200mm×10mm long square steel plate. The through hole at the center of the square plate (4) has a diameter of 40mm. The square plate (4) is provided with a connection hole with a center point of 35mm on each side. The inner thread diameter of the connection hole is 10mm, the pitch is 1.5mm, and there is one connection hole on each side, for a total of four connection holes.

6. A new type of sprayed concrete and surrounding rock bonding strength testing device according to claim 1, characterized in that: The connecting screw in the connecting hole is 100 mm long and 10 mm in diameter. The connecting nut (6) is a hexagonal flange face toothed nut with a size of 10 mm, a thickness of 8.8 mm, a flange diameter of 14 mm, and a flange diameter of 19 mm. The leveling nut is a hexagonal flat flange nut with a size of 10 mm, a flange diameter of 22 mm, a flange thickness of 2.5 mm, a flange diameter of 17 mm, and a nut height of 14.5 mm. The flange faces the direction of the square plate (4) and is perpendicular to the connecting hole. The connecting screw is screwed into the back of the hexagonal flat flange nut welded to the square plate (4). The end of the connecting screw is connected to the hexagonal flange face toothed nut, and the toothed flange faces the sprayed concrete (2). After fixing, the square plate (4) is leveled.

7. A novel sprayed concrete and surrounding rock bonding strength testing device according to claim 1, characterized in that: The screw in the expansion screw (7) has a diameter of 10 mm and a length of 150 mm, and is made of Q235 round steel.

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