A surface strain gauge installation device and method for steel arch frames in tunnels

Abstract

This invention discloses an installation device and method for surface strain gauges on steel arch frames used in tunnels. The device includes a handheld component with a telescopic mechanism at one end. Both ends of the telescopic mechanism are detachably connected to clamping columns. The clamping columns slide through the inner baffle of a U-shaped plate and connect to strain gauge grippers. The clamping columns are elastically connected to clamping components via grooves on their surfaces. The clamping columns also have limiting blocks. The limiting blocks and clamping components are located on both sides of the inner baffle and contact the inner baffle to position the U-shaped plate. When the clamping components are positioned at a set location on the clamping columns so that they contact the outer side of the inner baffle, the clamping columns can press the strain gauges against the inner side of the steel arch frame flange via the strain gauge grippers. This installation device overcomes the defects of welding installation and has low operational risk.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, specifically to a surface strain gauge installation device and method for steel arch frames used in tunnels. Background Technology

[0002] During tunnel construction, after the tunnel body is excavated, the tunnel is prone to deformation and collapse as the surrounding rock stress is released. Therefore, it is necessary to establish an initial support system in a timely manner to provide support and ensure construction safety. After the initial support system is established, stress monitoring of the steel arch frame in the initial support system is required to grasp the stress changes of the initial support system in real time, thereby assessing the support status of the steel arch frame and providing early warning of tunnel arch deformation and collapse accidents.

[0003] Currently, strain gauges used in tunnels are steel-wire cylindrical surface strain gauges, and the common installation method is:

[0004] 1. When laying out the tunnel, first use gauze or paper to polish the surface of the steel arch frame at the measuring point to remove rust and contaminants from its surface;

[0005] 2. Place the two hollow mounting blocks in the correct positions and tighten them at both ends of the steel wire strain gauge core.

[0006] 3. Weld the bottom surface of the mounting block to the inner side of the steel arch frame flange using electric welding;

[0007] 4. Loosen the fifteen-threaded post of the mounting block, remove the steel wire strain gauge replacement core, and replace it with a real steel wire strain gauge;

[0008] 5. Tighten the strain gauge again with a wrench, then cover the strain gauge with a protective cover welded by electric welding, and finally tidy up the wires.

[0009] This installation method has the following main problems: First, the working space is too small when installing strain gauges to monitor the stress of the steel arch frame; second, the strain gauges are welded to the steel arch frame via mounting blocks, but due to the small bottom surface of the mounting blocks, the welding is not very strong and is prone to falling off, requiring multiple welding operations, which greatly slows down the construction progress; third, the strain gauges are welded to the steel arch frame via mounting blocks, without direct contact, resulting in large errors in the measurement data; fourth, this method is very dangerous, and the high temperature generated during welding can easily damage the strain gauges, reducing project efficiency; fifth, the steel arch frame is too tall, requiring the use of ladders and other tools during installation, increasing the operational risk; sixth, due to the high thermal conductivity of the iron material, workers are easily burned during welding. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a surface strain gauge installation device for steel arch frames in tunnels. This device eliminates the need for welding and ladders during strain gauge installation, and allows for the installation of two strain gauges at a time. This reduces the workload of testing personnel, improves installation efficiency, and results in more accurate test results.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0012] In a first aspect, embodiments of the present invention provide a surface strain gauge installation device for a steel arch frame in a tunnel, including a handheld component. The end of the handheld component is provided with a telescopic mechanism. Both ends of the telescopic mechanism are detachably connected to clamping columns. The clamping columns slide through the inner baffle of a U-shaped plate and are connected to strain gauge grippers. The clamping columns are elastically connected to clamping components through grooves provided on the column surface. The clamping columns are also provided with limiting blocks. The limiting blocks and clamping components are located on both sides of the inner baffle and contact the inner baffle to position the U-shaped plate. The clamping components are located at a set position on the clamping columns so that when the clamping components contact the outer side of the inner baffle, the clamping columns can press the strain gauges onto the inner side of the flange of the steel arch frame through the strain gauge grippers.

[0013] Optionally, the handheld component adopts an L-shaped structure, including a first handheld part and a second handheld part vertically connected to the end of the first handheld part, the second handheld part being connected to a telescopic mechanism.

[0014] Optionally, the first hand-held part is equipped with a handle.

[0015] Optionally, the second hand-held part is a telescopic structure, including a fixed part fixed to the first hand-held part and a telescopic part telescopically connected to the fixed part, wherein the fixed part is hinged to both sides with a first connecting rod, the telescopic part is hinged to both sides with a second connecting rod, the first connecting rod and the second connecting rod on the same side are hinged together and detachably connected to the clamping column at the hinge position.

[0016] Optionally, one end of the telescopic part is telescopically connected to the fixed part, and the other end is provided with a push block.

[0017] Optionally, the surface of the jacking block that contacts the steel arch frame is provided with a flexible pad.

[0018] Optionally, the telescopic mechanism is provided with a pin at its end, and the clamping column is provided with a nut that matches the pin at its end, and the nut can be fitted around the outer circumference of the pin.

[0019] Optionally, the strain gauge gripper includes a first clamping member and a second clamping member that can open and close, and the surfaces of the first clamping member and the second clamping member that are in contact with the strain gauge are provided with flexible pads.

[0020] Optionally, one side of the clamping member is connected to the bottom groove surface of the groove through an elastic element, and the other side forms a set acute angle with the axis of the clamping column, and the distance between the end near the strain gauge claw and the axis of the clamping column is less than the distance between the other end and the axis of the clamping column.

[0021] Secondly, embodiments of the present invention provide a method for installing the surface strain gauge device for a steel arch frame in a tunnel as described in the first aspect, comprising the following steps:

[0022] The strain gauge is initially fixed using strain gauge clamps, and the clamping parts and limiting blocks are used to position the U-shaped plate so that after the entire installation device is fitted with the steel arch frame, the outer baffles of the U-shaped plates on both sides of the telescopic mechanism are in contact with the outer side of the flange of the steel arch frame.

[0023] The telescopic mechanism drives the clamping column to move until the clamping part extends out under the action of the elastic element and contacts the outer side of the inner baffle. The strain gauge gripper drives the strain gauge to press against the inner side of the steel arch frame flange, thus completing the fixation of the strain gauge.

[0024] Separate the clamping column from the telescopic mechanism to install the next strain gauge.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The strain gauge installation device of the present invention, under the action of the clamping component and the limiting block, allows the outer baffle of the U-shaped plate to fit against the outer side of the steel arch flange. The telescopic mechanism drives the clamping column to move, thereby pressing the strain gauge against the inner side of the steel arch. Locking is achieved by the contact between the clamping component and the inner baffle, and the installation of two strain gauges is completed simultaneously. No welding operation is required during use, making installation convenient and quick. It avoids the defects of welding installation with installation blocks, such as easy detachment, slowing down the construction progress, damage to the strain gauge by high temperature, and burns to operators. Moreover, the strain gauge directly contacts the inner side of the steel arch, resulting in more accurate measurement results.

[0027] 2. In the strain gauge installation device of the present invention, the second hand-held part is a telescopic structure. After the telescopic part of the second hand-held part contacts the steel arch frame, it moves in conjunction with the first connecting rod and the second connecting rod. The operator can realize the telescopic movement of the telescopic structure by moving the first hand-held part on the ground, thereby driving the movement of the clamping column. There is no need to climb the ladder to operate during installation, and the operation risk is low.

[0028] 3. In the strain gauge installation device of the present invention, the telescopic mechanism is connected to the clamping column by a pin and a nut. The telescopic mechanism and the clamping column can be separated simply by moving the pin along the axis of the pin. The operation is convenient and can be carried out on the ground by moving the hand-held part, without the need for climbing ladders, thus reducing the risk of operation. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0031] Figure 2 This is a schematic diagram of the cooperation between the handheld component and the telescopic mechanism in Embodiment 1 of the present invention;

[0032] Figure 3 This is a schematic diagram of the clamping column and the U-shaped plate in Embodiment 1 of the present invention;

[0033] Among them, 1. steel arch frame, 2. U-shaped plate, 2-1. upper baffle, 2-2. inner baffle, 2-3. outer baffle, 3. surface strain gauge, 4. hand-held part, 4-1. first hand-held part, 4-2. second hand-held part, 5. handle, 6. first connecting rod, 7. second connecting rod, 8. pin, 9. pin, 10. jacking block, 11. clamping column, 12. hexagonal nut, 13. flexible pad, 14. clamping part, 15. limiting block, 16. strain gauge gripper. Detailed Implementation

[0034] Example 1:

[0035] This embodiment provides a surface strain gauge mounting device for a steel arch frame, such as... Figures 1-3 As shown, the device includes a handheld component 4, which allows the operator to operate the entire installation device. The end of the handheld component is equipped with a telescopic mechanism that enables telescopic movement to both sides. Both ends of the telescopic mechanism are detachably connected to clamping columns. Each clamping column at both ends of the telescopic mechanism is equipped with a U-shaped plate 2. The U-shaped plate includes an upper baffle 2-1, an inner baffle 2-2 at the inner end of the upper baffle 2-1, and an outer baffle 2-3 at the outer end. The clamping column passes vertically through the inner baffle and is slidably connected to the inner baffle. The outer baffle is used to contact the outer side of the flange of the steel arch frame 1.

[0036] One end of the clamping column is detachably connected to the telescopic mechanism, and the other end passes through the inner baffle and is connected to the strain gauge gripper. The clamping column is elastically connected to the clamping member through the groove set on the column surface. With this setting, when the clamping column moves along the inner baffle, the clamping member can move from the inside of the inner baffle to the outside and contact the outer side of the inner baffle, preventing the clamping column 11 from moving in the opposite direction. At the same time, when the outer baffle is in contact with the outer side of the steel arch frame flange, the clamping column can press the surface strain gauge 3 onto the inner side of the steel arch frame flange through the strain gauge gripper, thereby fixing the surface strain gauge.

[0037] In this embodiment, the handheld component adopts an L-shaped structure, including a first handheld part 4-1 and a second handheld part 4-2 disposed at the end of the first handheld part. Both the first handheld part 4-1 and the second handheld part 4-2 adopt a rod-shaped structure. The length of the first handheld part 4-1 meets the needs of the operator to install the strain gauge on the ground.

[0038] A handle 5 is installed on the first hand part 4-1 to facilitate the operator's grip on the first hand part 4-1. The handle 5 is covered with an anti-slip rubber pad, and the surface of the anti-slip rubber pad is provided with anti-slip texture.

[0039] The second hand-held part 4-2 adopts a telescopic structure, including a fixed part and a telescopic part that is inserted into the fixed part and telescopically connected to the fixed part. The fixed part is fixed perpendicularly to the first hand-held part 4-1. The length of the telescopic part is greater than the length of the fixed part. The inner surface of the fixed part is in contact with the outer surface of the telescopic part. In its natural state, it is fixed by friction. Only when the external force reaches the set value can the telescopic movement be realized.

[0040] The second hand-held part 4-2 is connected to a telescopic mechanism, which can drive the clamping columns at both ends of it to move.

[0041] The telescopic mechanism includes two first links 6 and two second links 7. One first link 6 and one second link 7 are provided on one side of the second hand-held part 4-2, and another first link 6 and another second link 7 are symmetrically provided on the other side.

[0042] One end of the first link 6 is hinged to the end of the fixed part via a pin, the other end of the first link 6 is hinged to one end of the second link 7 via a pin 8, and the other end of the second link 7 is hinged to the end of the telescopic part via a pin 9.

[0043] The telescopic part is provided with a push block 10 at the end outside the fixed part. The push block 10 is used to contact the web between the flange of the steel arch frame 1.

[0044] To prevent damage to the steel arch frame 1 when the jacking block 10 applies jacking force to the steel arch frame 1, a flexible pad is provided on the surface of the jacking block 10 that contacts the steel arch frame 1. In this embodiment, the flexible pad is a sponge pad or a rubber pad.

[0045] The operator moves the handheld component until the push block 10 contacts the web of the steel arch frame 1. Then the handheld component continues to move toward the web, and the telescopic part retracts into the fixed part. Through the first link 6 and the second link 7, the clamping column 11 moves outward.

[0046] During operation, workers only need to hold the handle on the ground to operate it, without the need to climb ladders, so the operation is low-risk.

[0047] The clamping column 11 is detachably connected to the first connecting rod 6 and the second connecting rod 7 at the intersection. Specifically, the end of the clamping column 11 is provided with a nut, which is a hexagonal nut 12. The hexagonal nut 12 can be fitted around the outer circumference of the pin 8 between the first connecting rod 6 and the second connecting rod 7, so as to realize the detachable connection between the clamping column 11 and the telescopic mechanism.

[0048] In use, simply move the telescopic mechanism along the axis of pin 8 to separate the clamping column 11 from the telescopic mechanism. Operators can operate it from the ground by holding the handle 5, which is convenient and quick, without the need for ladders to climb and the operation is low in risk.

[0049] The clamping column 11 passes through an opening in the inner baffle 2-2. The diameter of the opening is larger than the diameter of the strain gauge and the diameter of the clamping column. The end of the clamping column 11 that extends between the inner baffle 2-2 and the outer baffle 2-3 is provided with a strain gauge gripper 16.

[0050] The strain gauge gripper 16 includes a first clamping member and a second clamping member. The ends of the first clamping member and the second clamping member on the same side are rotatably connected to the clamping post 11 through a hinge shaft, thereby realizing the opening and closing of the first clamping member. In its natural state, the first clamping member and the second clamping member are fixed to the clamping post through friction, which can apply a certain pressure to the strain gauge for initial fixation.

[0051] The first and second clamping members are provided with flexible pads 13 on their surfaces for clamping the strain gauge. In this embodiment, the flexible pads 13 are made of sponge to avoid damage to the strain gauge when the first and second clamping members clamp it.

[0052] The clamping column 11 has a groove on its cylindrical surface. The groove is a rectangular groove. The clamping column 11 is elastically connected to the clamping member 14 through the rectangular groove. Specifically, an elastic member is provided in the groove. The elastic member is a stainless steel spring. One end of the stainless steel spring is fixed to the bottom groove surface of the groove, and the other end is fixed to the clamping member 14.

[0053] In this embodiment, the clamping member 14 adopts a right-angled triangle structure. Its bottom surface is the surface corresponding to the long right-angle side, which is connected to the stainless steel spring. Its top surface is the surface corresponding to the hypotenuse, which forms a set acute angle with the axis of the clamping column. The distance between the end of the top surface near the strain gauge claw 12 and the axis of the clamping column is less than the distance between the other end and the axis of the clamping column 11.

[0054] With this configuration, when the clamping column 11 moves toward the outer baffle 2-3, the opening of the inner baffle 2-2 can press the clamping member 14 into the groove, allowing the clamping member 14 to pass over the inner baffle 2-2. After passing over the inner baffle 2-2, the clamping member 14 can pop out under the action of the stainless steel spring, and the surface where the shorter right angle side is located contacts the outer surface of the inner baffle, preventing the clamping column from moving in the opposite direction.

[0055] In this embodiment, the clamping member 14 is set at a predetermined position on the cylindrical surface of the clamping column 11. The distance between the clamping member 14 and the end of the clamping column 11 connected to the telescopic mechanism is the diameter of the surface strain gauge 3. The length of the clamping column 11 is the distance between the inner baffle 2-2 and the outer baffle 2-3. After the clamping member 14 passes over the inner baffle 2-2 and contacts the outer side of the inner baffle 2-2, the strain gauge claws 12 open as the clamping column 11 moves. The clamping column 11 can use the strain gauge claws 12 to press the surface strain gauge 3 against the inner side of the outer baffle. Then, the surface strain gauge 3 is pressed and fixed to the inner side of the flange of the steel arch frame 1 by the squeezing action of the flexible pad 13 of the strain gauge claws 12.

[0056] In this embodiment, a limiting block 15 is also fixedly provided on the column surface of the clamping column 11. The limiting block 15 and the clamping member 14 are located on both sides of the inner baffle 2-2. In the initial state, the clamping member 14 and the limiting block 15 are in contact with the inner baffle 2-2, thereby limiting the position of the inner baffle 2-2. The telescopic mechanism is kept fixed by the friction between the fixed part and the telescopic part, so that when the entire installation device is matched with the steel arch frame, the inner side of the outer baffle 2-3 of the two U-shaped plates 2 can be fitted with the outer side of the flange of the steel arch frame 1.

[0057] Example 2

[0058] This embodiment provides a method for installing the steel arch frame surface strain gauge device as described in Embodiment 1, including the following steps:

[0059] The two surface strain gauges 3 are initially fixed using the two strain gauge clamps 12.

[0060] The ends of the two clamping columns 11 are respectively connected to the pins 8 at the hinge positions of the first link 6 and the second link 7 of the telescopic mechanism via hexagonal nuts 12.

[0061] The staff member holds handle 5 and places the entire installation device in the target position so that the inner surface of the outer side plate 2-3 of the two U-shaped plates contacts the outer side of the flange of the steel arch frame 1.

[0062] Then, the staff moves the telescopic mechanism toward the web of the steel arch frame 1 by using handle 5 until the jacking block 10 contacts the web of the steel arch frame 1.

[0063] Continuing the movement, under the action of the web plate, the telescopic part retracts into the fixed part. Through the first link 6 and the second link 7, the clamping column 11 moves to both sides. After passing the inner baffle 2-2, the clamping member 14 extends again under the action of the stainless steel spring and contacts the outer side of the inner baffle 2-2 to prevent the clamping column 11 from moving in the opposite direction. At the same time, the clamping column 11 uses the strain gauge claw 16 to press the surface strain gauge 3 onto the inner side of the flange of the steel arch frame 1, thus completing the installation of two surface strain gauges 3. The upper baffle also protects the surface strain gauges 3, preventing them from being contaminated by the spray.

[0064] The operator holds the handle and moves the telescopic mechanism to separate the pin 8 between the first link 6 and the second link 7 from the hexagonal nut 12 at the end of the clamping column 11, thus completing the separation of the clamping column 11 from the telescopic mechanism.

[0065] At this point, the handheld unit and telescopic mechanism are used for installing the surface strain gauges at the next location. After connecting the data cables of all surface strain gauges to the data acquisition instrument, the obtained data can be analyzed to determine the stress of the steel arch frame.

[0066] The installation device used in this embodiment requires no welding operation, making installation convenient and quick. It avoids the drawbacks of welding installation with installation blocks, such as easy detachment, slowing down the construction progress, damage to the strain gauge due to high temperature, and burns to workers. Moreover, the strain gauge directly contacts the inner side of the steel arch frame, resulting in more accurate measurement results. Furthermore, it can be operated from the ground by moving the handheld part, eliminating the need for climbing ladders and reducing operational risks.

[0067] The installation device in this embodiment, using surface strain gauges at different heights, greatly improves work efficiency. Since the operator works on the ground, it efficiently solves the problem of confined working environments. The height is adjustable, making it suitable for monitoring the initial support stress at different locations in the tunnel. Furthermore, it is reusable, making steel arch stress testing more convenient, reducing the labor intensity of testing personnel, and resulting in more accurate test results.

[0068] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A tunnel steel arch surface strain gauge mounting device, characterized by, The hand-held piece is provided with a telescopic mechanism at its end, and the two ends of the telescopic mechanism are detachably connected with clamping columns, the clamping columns are connected with strain gauge clamping jaws after sliding through the inner baffle of the U-shaped plate, the clamping columns are elastically connected with clamping members through the grooves arranged on the column surface, the clamping columns are further provided with limiting blocks, the limiting blocks and the clamping members are respectively located on the two sides of the inner baffle and in contact with the inner baffle to position the U-shaped plate, and when the clamping members are in contact with the outer side surface of the inner baffle, the clamping columns can press the strain gauges against the inner side surface of the steel arch wing through the strain gauge clamping jaws; The hand-held piece adopts an L-shaped structure, and includes a first hand-held part and a second hand-held part connected with the end of the first hand-held part perpendicularly, and the second hand-held part is connected with the telescopic mechanism; The second hand-held part is of a telescopic structure, and includes a fixed part fixed with the first hand-held part and a telescopic part telescopically connected with the fixed part, wherein the two sides of the fixed part are hingedly connected with first connecting rods, the two sides of the telescopic part are hingedly connected with second connecting rods, the first connecting rods and the second connecting rods on the same side are hingedly connected and detachably connected with the clamping columns at the hinged positions; One end of the telescopic part is telescopically connected with the fixed part, and the other end is provided with a pushing block.

2. A steel arch tunnel surface strain gauge mounting device as claimed in claim 1, characterised in that, The first hand-held part is provided with a handle.

3. A steel arch tunnel surface strain gauge mounting device as claimed in claim 1, characterised in that, The surface of the pushing block used for contacting the steel arch is provided with a flexible pad.

4. A steel arch tunnel surface strain gauge mounting device as claimed in claim 1, characterised in that, The end of the telescopic mechanism is provided with a pin shaft, and the end of the clamping column is provided with a nut cap matched with the pin shaft, and the nut cap can be sleeved on the outer periphery of the pin shaft.

5. A steel arch tunnel surface strain gauge mounting device as claimed in claim 1, wherein, The strain gauge clamping jaw includes first and second clamping members capable of being opened and closed, and the surfaces of the first and second clamping members used for contacting the strain gauges are provided with flexible pads.

6. A steel arch tunnel surface strain gauge mounting device as claimed in claim 1, characterised in that, One side surface of the clamping member is connected with the bottom groove surface of the groove through an elastic member, the other side surface forms a set acute angle with the axis of the clamping column, and the distance between the one end close to the strain gauge clamping jaw and the axis of the clamping column is smaller than the distance between the other end and the axis of the clamping column.

7. A method of using a tunnel steel arch surface strain gauge mounting device according to any one of claims 1-6, characterized in that, The method includes the following steps: The strain gauges are preliminarily fixed by the strain gauge clamping jaws, the U-shaped plate is positioned by the clamping members and the limiting blocks, and the outer baffle of the U-shaped plate on the two sides of the telescopic mechanism is attached to the outer side surface of the wing of the steel arch after the whole installation device is matched with the steel arch; The telescopic mechanism drives the clamping columns to move until the clamping members are extended and in contact with the outer side surface of the inner baffle after the clamping members pass through the inner baffle under the action of the elastic members, the strain gauge clamping jaws drive the strain gauges to be pressed against the inner side surface of the wing of the steel arch, and the fixation of the strain gauges is completed; The clamping columns are separated from the telescopic mechanism to install the next strain gauge.

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