Simulation system and test method for prefabrication of cracks in surrounding rock of tunnel under loading and unloading conditions

Abstract

The present invention discloses a tunnel surrounding rock crack prefabrication simulation system and a test method under loading and unloading conditions in the field of geological engineering technology, comprising a frame, two groups of vertical frame plates, two groups of horizontal frame plates, a plurality of rivets, a bottom plate, a plurality of screw and bolt assemblies, a rock-like material, a specimen prefabrication mold, a loading and unloading system and a grouting test system. The surrounding rock crack prefabrication simulation system is controllable for the prefabrication of the cracks, that is, the shape and size of the cracks, the spatial position and the connectivity between the cracks can all be controlled, and the original shape of the tunnel surrounding rock cracks can be restored. At the same time, the grouting specimen prefabrication, the grouting process and the grouting effect detection do not require the use of different devices, and the operation is simple and convenient. In addition, the grouting test system can restore the stress changes of the tunnel surrounding rock under actual loading and unloading conditions. The obtained results are close to the actual situation and can accurately reflect the on-site application situation.

Description

Technical Field

[0001] The invention relates to the technical field of geological engineering, and in particular to a tunnel surrounding rock crack prefabrication simulation system and a test method under loading and unloading conditions. Background Art

[0002] In recent years, with the rapid development of underground construction projects, the instability characteristics of tunnel surrounding rock during excavation and the tunnel surrounding rock support technology have attracted more and more attention from industry insiders. The tunnel surrounding rock is already full of joints and fissures. Affected by the excavation disturbance, the stress distribution inside the surrounding rock changes, causing micro-cracks to expand and develop continuously. The cracks in some stress concentration areas continue to expand until they penetrate each other, forming macro-cracks, causing rock mass instability, seriously affecting the mining progress, increasing production costs, and threatening the safe production of mines. Among the existing methods to improve the stability of surrounding rocks, grouting reinforcement technology has been widely used due to its convenient operation, strong adaptability, and good support effect. In order to explore the mechanical properties and fracture laws of rock-slurry stone composite materials after grouting, rock samples after grouting are often taken for indoor mechanical testing. However, the on-site drilling method is affected by the randomness of the surrounding rock structure surface distribution, and the test results are often irregular. Therefore, it is necessary to simulate the morphological characteristics of surrounding rock cracks under excavation disturbance to produce grouting specimens for testing that meet the actual crack conditions.

[0003] The existing tunnel surrounding rock crack specimen preparation system and grouting test method have the following shortcomings: the existing surrounding rock crack prefabrication system prefabricates the cracks mostly randomly, and the shape, size, spatial position and connectivity of the cracks cannot be controlled, and the original shape of the tunnel surrounding rock cracks cannot be restored; the existing grouting specimen prefabrication, grouting process and grouting effect detection require the use of different devices, and the operation is cumbersome and not simple enough. Finally, since the existing grouting test system cannot restore the stress changes of the tunnel surrounding rock under actual loading and unloading conditions, the obtained results are greatly different from the actual situation and cannot accurately reflect the on-site application conditions. Based on this, the present invention designs a tunnel surrounding rock crack prefabrication simulation system and test method under loading and unloading conditions to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a tunnel surrounding rock crack prefabrication simulation system and test method under loading and unloading conditions to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a prefabrication simulation system for tunnel surrounding rock cracks under loading and unloading conditions, comprising a frame, two groups of vertical frame plates, two groups of horizontal frame plates, a plurality of rivets, a bottom plate, a plurality of screw and bolt assemblies, rock-like materials, a specimen prefabrication mold, a loading and unloading system and a grouting test system, wherein the bottom plate is installed on the bottom plate of the frame, two groups of the horizontal frame plates are horizontally fixed on the middle longitudinal columns on both sides of the frame at a relative interval, and a vertical frame plate is fixed in the middle of the upper surface of the two groups of the horizontal frame plates;

[0006] The specimen prefabricated mold comprises a left loading plate, a right loading plate, an upper loading plate, a front baffle, a rear baffle and an arched tough PVC film, wherein the left loading plate, the right loading plate, the upper loading plate, the front baffle and the rear baffle are assembled and spliced ​​into a closed structure by rivets, and the left loading plate and the right loading plate are respectively vertically mounted on the upper surfaces of the horizontal frame plates on the left and right sides by screw and bolt assemblies, and the arched tough PVC film is attached to the inner side of the sealing structure and fixed between the spaced upper surfaces of the two groups of the horizontal frame plates, and a rock-like material is poured in the cavity formed by the arched tough PVC film, the sealing structure and the horizontal frame plates;

[0007] The loading system comprises an upper jack group A, a left jack group B, a right jack group C, a bottom jack group D, a left semi-arc column loading block and a right semi-arc column loading block. The upper jack group A is fixedly installed at the top center of the frame through a cross beam and is directly opposite to the upper loading plate. The left jack group B and the right jack group C are respectively horizontally fixed on the longitudinal columns on both sides of the frame through a cross beam and penetrate the middle of the vertical frame plate. The bottom jack group D is installed at the middle of the upper surface of the bottom plate through a cushion block. The upper jack group A, the left jack group B, the right jack group C and the bottom jack group D are in even number and are evenly divided into two rows. The left semi-arc column loading block and the right semi-arc column loading block are respectively installed on the left and right rows of jacks of the bottom jack group D, and the left semi-arc column loading block and the right semi-arc column loading block are distributed with a gap.

[0008] The grouting test system includes a tough PVC grouting hose, a reserved PVC pipe hole and a grouting hole, wherein the grouting hole is located at the bottom of the arched tough PVC film, the tough PVC grouting hose is bonded to the upper part of the arched tough PVC film and the two are integrated into a whole, the grouting hole extending from the lower part of the tough PVC grouting hose extends through to the other side of the arched tough PVC film, and a plurality of reserved PVC pipe holes are distributed on the upper part of the tough PVC grouting hose.

[0009] Furthermore, the left loading plate, the right loading plate and the upper loading plate are all made of steel plates.

[0010] Furthermore, the reserved PVC pipe hole adopts a mounting hole with a smaller hole diameter.

[0011] Furthermore, the inner wall of the outer end of the grouting hole is provided with a thread.

[0012] Furthermore, the grouting hole is located in the middle of the arched tough PVC film, and the diameter of the grouting hole is smaller than the gap between the left semi-arc column loading block and the right semi-arc column loading block.

[0013] A test method for a tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions comprises the following steps:

[0014] S1: The left loading plate and the right loading plate are fixed on the horizontal frame plate by screw and bolt assemblies; the front baffle plate and the rear baffle plate are spliced ​​and fixed with rivets to form a groove structure; the bottom jack group D is adjusted to move the left half arc column loading block and the right half arc column loading block upward, lifting the arched tough PVC film to form an arc bottom;

[0015] S2: Close the grouting hole, temporarily close the reserved PVC pipe hole with soluble paper, and apply lubricant on the inner wall of the closed groove to facilitate demoulding later;

[0016] S3: Prefabricate rock-like materials according to the surrounding rock conditions of the tunnel, pour them into the trough mold, and wait for solidification and curing to be complete;

[0017] S4: Remove the screw and bolt assembly to allow the left loading plate and the right loading plate to move freely, remove the front baffle and the rear baffle, and install the upper loading plate;

[0018] S5: Adjust the upper jack group A, the left jack group B, the right jack group C, and the bottom jack group D to achieve the loading and unloading effect on the prefabricated specimen, simulate the stress condition of the surrounding rock after tunnel mining, restore the loading and unloading damage effect of the tunnel surrounding rock during operation, generate cracks, and complete the prefabrication of the tunnel surrounding rock cracks;

[0019] S6: Re-anchor the left loading plate and the right loading plate with screw and bolt assemblies, install the front baffle, the rear baffle, and the upper loading plate and fix them with rivets to form a closed space; adjust the left and right rows of jacks of the bottom jack group D so that the left half-arc column loading block and the right half-arc column loading block move upward to support the arched tough PVC film;

[0020] S7: Open the bottom grouting hole, connect the tough PVC grouting hose, and inject grouting into the arched tough PVC film. The slurry melts the soluble paper and enters the cracked sample. After the grouting is completed, remove the grouting equipment, and repeat step S4 after the slurry solidifies.

[0021] S8: Adjust the upper jack group A, the left jack group B, the right jack group C, and the bottom jack group D to realize the loading and unloading effect on the grouting sample, simulate the stress condition of the surrounding rock after tunnel mining, restore the loading and unloading destructive effect of the tunnel surrounding rock during operation, and perform the required test operations.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the prefabrication of the cracks in the surrounding rock by the simulation system for prefabrication of the cracks is controllable, that is, the shape and size of the cracks, the spatial position and the connectivity between the cracks can all be controlled, and the original shape of the cracks in the surrounding rock of the tunnel can be restored. At the same time, the prefabrication of grouting specimens, the grouting process and the detection of grouting effects do not require the use of different devices, and the operation is simple and convenient. Moreover, the grouting test system can restore the stress changes of the tunnel surrounding rock under actual loading and unloading conditions. The obtained results are close to the actual situation and can accurately reflect the on-site application conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0025] Figure 2 It is a cross-sectional schematic diagram of the present invention;

[0026] Figure 3 It is a schematic diagram of the grouting system of the present invention;

[0027] Figure 4 It is a schematic diagram of the front and rear baffles of the present invention.

[0028] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0029] 1-frame, 2-upper jack group A, 3-left jack group B, 4-right jack group C, 5-bottom jack group D, 6-vertical frame plate, 7-horizontal frame plate, 8-left loading plate, 9-right loading plate, 10-upper loading plate, 11-arched tough PVC film, 12-tough PVC grouting hose, 13-reserved PVC pipe hole, 14-grouting hole, 15-left semi-arc column loading block, 16-right semi-arc column loading block, 17-rivet, 18-bottom plate, 19-screw bolt assembly, 20-front baffle, 21-rear baffle, 22-rock-like material. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0032] See also Figure 1-4 The present invention provides a technical solution: a prefabricated simulation system for tunnel surrounding rock cracks under loading and unloading conditions, comprising a frame 1, two groups of vertical frame plates 6, two groups of horizontal frame plates 7, a plurality of rivets 17, a bottom plate 18, a plurality of screw and bolt assemblies 19, a rock-like material 22, a specimen prefabrication mold, a loading and unloading system and a grouting test system, wherein the bottom plate 18 is installed on the bottom plate of the frame 1, and the two groups of horizontal frame plates 7 are horizontally fixed on the middle longitudinal columns of both sides of the frame 1 at a relative interval, and the middle of the upper surface of the two groups of horizontal frame plates 7 is fixed with a vertical frame plate 6;

[0033] The specimen prefabricated mold includes a left loading plate 8, a right loading plate 9, an upper loading plate 10, a front baffle 20, a rear baffle 21 and an arched tough PVC film 11. The left loading plate 8, the right loading plate 9, the upper loading plate 10, the front baffle 20 and the rear baffle 21 are assembled and spliced ​​into a closed structure by rivets 17. The left loading plate 8 and the right loading plate 9 are respectively vertically installed on the upper surfaces of the left and right side cross-frame plates 7 by screw and bolt assemblies 19. The arched tough PVC film 11 is attached to the inner side of the sealing structure and fixed between the upper surfaces of the intervals of the two groups of cross-frame plates 7. The cavity formed by the arched tough PVC film 11, the sealing structure and the cross-frame plates 7 is cast with rock-like material 22.

[0034] The loading system includes an upper jack group A 2, a left jack group B 3, a right jack group C 4, a bottom jack group D 5, a left semi-arc column loading block 15 and a right semi-arc column loading block 16. The upper jack group A 2 is fixedly installed at the top center of the frame 1 through a cross beam and is directly opposite to the upper loading plate 10. The left jack group B 3 and the right jack group C 4 are horizontally fixed on the longitudinal columns on both sides of the frame 1 through a cross beam and pass through the middle of the vertical frame plate 6. The bottom jack group D 5 is installed in the middle of the upper surface of the bottom plate 18 through a pad. The side jacks A group 2, the left jacks B group 3, the right jacks C group 4 and the bottom jacks D group 5 are in even number and are evenly divided into two rows. The left and right rows of jacks of the bottom jacks D group 5 are respectively installed with a left semi-arc column loading block 15 and a right semi-arc column loading block 16. The left semi-arc column loading block 15 and the right semi-arc column loading block 16 are distributed with a gap. By adjusting the bottom jacks D group 5, the pressure on the left semi-arc column loading block 15 or the right semi-arc column loading block 16 can be loaded or unloaded, and the multi-directional application and unloading of force can be realized.

[0035] The grouting test system includes a tough PVC grouting hose 12, a reserved PVC pipe hole 13 and a grouting hole 14. The grouting hole 14 is located at the bottom of the arched tough PVC film 11. The tough PVC grouting hose 12 is bonded to the upper part of the arched tough PVC film 11 and the two are integrated into a whole. The grouting hole 14 extending from the lower part of the tough PVC grouting hose 12 extends through to the other side of the arched tough PVC film 11. A plurality of reserved PVC pipe holes 13 are distributed on the upper part of the tough PVC grouting hose 12, which can realize grouting of the sample in the mold.

[0036] The left loading plate 8, the right loading plate 9 and the upper loading plate 10 are all made of steel plates.

[0037] The reserved PVC pipe hole 13 adopts a mounting hole with a smaller aperture, and its influence on the strength of the specimen can be ignored.

[0038] The inner wall of the outer end of the grouting hole 14 is provided with a thread, and the hole can be closed when grouting is not performed, and the toughness PVC grouting hose 12 can be directly connected during grouting.

[0039] The grouting hole 14 is located in the middle of the arched tough PVC film 11 , and the diameter of the grouting hole 14 is smaller than the gap between the left semi-arc column loading block 15 and the right semi-arc column loading block 16 .

[0040] A test method for a tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions comprises the following steps:

[0041] S1: The left loading plate 8 and the right loading plate 9 are fixed on the cross frame plate 7 by screw and bolt assemblies 19; the front baffle plate 20 and the rear baffle plate 21 are spliced ​​and fixed by rivets 17 to form a groove structure; the bottom jack D group 5 is adjusted so that the left semi-arc column loading block 15 and the right semi-arc column loading block 16 move upward, and the arched tough PVC film 11 is lifted to form an arc bottom;

[0042] S2: Close the grouting hole 14, temporarily close the reserved PVC pipe hole 13 with soluble paper, and apply lubricant on the inner wall of the formed closed groove to facilitate demoulding later;

[0043] S3: Prefabricate the rock-like material 22 according to the surrounding rock conditions of the tunnel, pour it into the trough mold, and wait for solidification and curing to be complete;

[0044] S4: Remove the screw and bolt assembly 19 so that the left loading plate 8 and the right loading plate 9 can move freely, remove the front baffle 20 and the rear baffle 21, and install the upper loading plate 10;

[0045] S5: Adjust the upper jack group A 2, the left jack group B 3, the right jack group C 4, and the bottom jack group D 5 to achieve the loading and unloading effect on the prefabricated specimen, simulate the stress condition of the surrounding rock after tunnel mining, restore the loading and unloading destructive effect of the tunnel surrounding rock during operation, generate cracks, and complete the prefabrication of the tunnel surrounding rock cracks;

[0046] S6: Re-anchor the left loading plate 8 and the right loading plate 9 with the screw bolt assembly 19, install the front baffle 20, the rear baffle 21, and the upper loading plate 10 and fix them with rivets 17 to form a closed space; adjust the left and right rows of jacks of the bottom jack D group 5 so that the left semi-arc column loading block 15 and the right semi-arc column loading block 16 move upward to support the arched tough PVC film 11;

[0047] S7: Open the bottom grouting hole 14, connect the tough PVC grouting hose 12, and inject grout into the arched tough PVC film 11. The slurry melts the soluble paper and enters the cracked sample. After the grouting is completed, remove the grouting equipment, and repeat step S4 after the slurry solidifies.

[0048] S8: Adjust the upper jack A group 2, the left jack B group 3, the right jack C group 4, and the bottom jack D group 5 to realize the loading and unloading effect on the grouting sample, simulate the stress condition of the surrounding rock after tunnel mining, restore the loading and unloading destructive effect of the tunnel surrounding rock during operation, and perform the required test operations.

[0049] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0050] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A prefabrication simulation system for tunnel surrounding rock cracks under loading and unloading conditions, comprising a frame (1), two sets of vertical frame plates (6), two sets of horizontal frame plates (7), a plurality of rivets (17), a bottom plate (18), a plurality of screw and bolt assemblies (19), a rock-like material (22), a specimen prefabrication mold, a loading and unloading system and a grouting test system, characterized in that: The bottom plate (18) is mounted on the bottom plate of the frame (1), and two groups of the horizontal frame plates (7) are fixed horizontally on the longitudinal columns in the middle of both sides of the frame (1) at a relative interval, and the middle of the upper surface of the two groups of the horizontal frame plates (7) are fixed with vertical frame plates (6); The specimen prefabricated mold comprises a left loading plate (8), a right loading plate (9), an upper loading plate (10), a front baffle (20), a rear baffle (21) and an arched tough PVC film (11); the left loading plate (8), the right loading plate (9), the upper loading plate (10), the front baffle (20) and the rear baffle (21) are assembled and spliced ​​into a closed structure by rivets (17); the left loading plate (8) and the right loading plate (9) are respectively vertically mounted on the upper surfaces of the left and right cross-frame plates (7) by screw and bolt assemblies (19); the arched tough PVC film (11) is attached to the inner side of the sealing structure and fixed between the spaced upper surfaces of the two groups of cross-frame plates (7); and a rock-like material (22) is cast in the cavity formed by the arched tough PVC film (11), the sealing structure and the cross-frame plates (7); The loading and unloading system comprises an upper jack group A (2), a left jack group B (3), a right jack group C (4), a bottom jack group D (5), a left semi-arc column loading block (15) and a right semi-arc column loading block (16); the upper jack group A (2) is fixedly mounted at the top center of the frame (1) via a cross beam and directly facing the upper loading plate (10); the left jack group B (3) and the right jack group C (4) are respectively horizontally fixed to the longitudinal columns on both sides of the frame (1) via a cross beam and penetrate the vertical frame plate ( 6) middle part, the bottom side jack group D (5) is installed on the middle part of the upper surface of the bottom plate (18) through a pad, the upper side jack group A (2), the left side jack group B (3), the right side jack group C (4) and the bottom side jack group D (5) are an even number and are evenly divided into two rows, and the left and right rows of jacks of the bottom side jack group D (5) are respectively installed with a left semi-arc column loading block (15) and a right semi-arc column loading block (16), and the left semi-arc column loading block (15) and the right semi-arc column loading block (16) are distributed with a gap; The grouting test system comprises a tough PVC grouting hose (12), a reserved PVC pipe hole (13) and a grouting hole (14); the grouting hole (14) is located at the bottom of the arched tough PVC film (11); the tough PVC grouting hose (12) is bonded to the upper part of the arched tough PVC film (11) and the two are fused into a whole; the grouting hole (14) extending from the lower part of the tough PVC grouting hose (12) extends through to the other side of the arched tough PVC film (11); and a plurality of reserved PVC pipe holes (13) are distributed on the upper part of the tough PVC grouting hose (12); The test method of the simulation system includes the following steps: S1: The left loading plate (8) and the right loading plate (9) are fixed to the cross frame plate (7) by means of screw bolt assemblies (19); the front baffle plate (20) and the rear baffle plate (21) are spliced ​​and fixed by means of rivets (17) to form a groove-shaped structure; the bottom jack group D (5) is adjusted so that the left semi-arc column loading block (15) and the right semi-arc column loading block (16) are moved upwards, and the arched tough PVC film (11) is lifted to form an arc-shaped bottom; S2: closing the grouting hole (14), temporarily closing the reserved PVC pipe hole (13) with soluble paper, and applying lubricant on the inner wall of the formed closed groove to facilitate demoulding later; S3: Prefabricate rock-like materials (22) according to the surrounding rock conditions of the tunnel, pour them into the trough mold, and wait for solidification and curing to be complete; S4: Remove the screw and bolt assembly (19) so that the left loading plate (8) and the right loading plate (9) can move freely, remove the front baffle (20) and the rear baffle (21), and install the upper loading plate (10); S5: adjusting the upper jack group A (2), the left jack group B (3), the right jack group C (4), and the bottom jack group D (5) to realize the loading and unloading of the prefabricated sample, simulating the stress condition of the surrounding rock after tunnel mining, restoring the loading and unloading destructive effect of the tunnel surrounding rock during operation, generating cracks, and completing the prefabrication of the tunnel surrounding rock cracks; S6: Re-anchor the left loading plate (8) and the right loading plate (9) with the screw bolt assembly (19), install the front baffle (20), the rear baffle (21), and the upper loading plate (10) and fix them with rivets (17) to form a closed space; adjust the left and right rows of jacks of the bottom jack group D (5) so that the left semi-arc column loading block (15) and the right semi-arc column loading block (16) move upward to support the arched tough PVC film (11); S7: Open the bottom grouting hole (14), connect the tough PVC grouting hose (12), and inject grouting into the arched tough PVC film (11). The grouting liquid melts the soluble paper and enters the cracked sample. After the grouting is completed, the grouting equipment is removed, and step S4 is repeated after the grouting liquid solidifies. S8: Regulate the upper jack group A (2), the left jack group B (3), the right jack group C (4), and the bottom jack group D (5) to realize the loading and unloading effect on the grouting sample, simulate the stress condition of the surrounding rock after tunnel mining, restore the loading and unloading destructive effect of the tunnel surrounding rock during operation, and perform the required test operation.

2. The tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions according to claim 1 is characterized by: The left loading plate (8), the right loading plate (9) and the upper loading plate (10) are all made of steel plates.

3. The tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions according to claim 1 is characterized by: The reserved PVC pipe hole (13) is a mounting hole with a smaller hole diameter.

4. The tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions according to claim 1 is characterized in that: The inner wall of the outer end of the grouting hole (14) is provided with a thread.

5. The tunnel surrounding rock crack prefabrication simulation system under loading and unloading conditions according to claim 1 is characterized in that: The grouting hole (14) is located in the middle of the arched tough PVC film (11), and the diameter of the grouting hole (14) is smaller than the gap between the left semi-arc column loading block (15) and the right semi-arc column loading block (16).

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