Shallow water concrete structure blasting effect test device

Abstract

The present invention discloses a blasting effect test device for concrete structures in shallow water, comprising a concrete target located in the center of the test water area, a target stress and strain acquisition device, a free-field pressure test device, and a data acquisition system connected to a trigger for controlling the explosion of explosives. The target stress and strain acquisition device comprises a concrete base block, a stress acquisition rod, and a wall reflection pressure sensor. The free-field pressure test device comprises a piezoelectric pressure sensor and a support rod. The support rod is arranged on the outside of the concrete target and has a cross-shaped bracket on its upper part. One end of the piezoelectric pressure sensor is connected to a counterweight block, and the other end is connected to and passes around the cross-shaped bracket through a hanging rope. The other end of the hanging rope is provided with a counterweight block. Through the test device, the blasting effect and damage influence law of the concrete pier in shallow water can be accurately obtained.

Description

Technical Field

[0001] The invention specifically relates to a shallow water concrete structure blasting effect test device, belonging to the technical field of shallow water blasting damage test. Background Art

[0002] Most existing techniques use high-speed cameras to capture images of concrete structures at the moment of blasting. The damage effects are then captured based on the changes in the images. However, these images fail to capture the damage to all surfaces of the concrete structure, particularly the surface facing the blast. Furthermore, underwater cameras are expensive in shallow water environments. Furthermore, under test conditions, the cameras cannot accurately capture damage images due to the influence of water quality and shock waves, making repeated damage tests unsuitable.

[0003] The effects of shallow underwater explosions on concrete piers primarily include shock waves, underwater reflections, diffraction waves, and reflected rarefaction waves from the water surface and the pier itself. Unlike the mechanism of concrete damage caused by explosives in air, the pier's response to blasts manifests primarily in compression and tension. The positive pressure and peak compressive stress on the pier's surface are primarily caused by the shock wave and underwater reflections, while the negative pressure and tensile stress are primarily caused by reflected rarefaction waves from the water surface and the pier itself. Due to the fluidity and isotropy of water, the concrete pier is subjected to the confining pressure of the shock wave, placing it under multi-directional stress.

[0004] The blasting damage effect of concrete piers in shallow water is the result of the superposition of complex stresses. In order to summarize the stress distribution and damage mode of concrete piers under different charging forms and different spatial positions, as well as the influence of charging parameters and blasting conditions on the damage effect of concrete piers, a shallow water concrete structure blasting effect test device is urgently needed to obtain accurate data. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a blasting effect test device for concrete structures in shallow water, so as to accurately obtain the blasting effect and damage influence law of concrete piers in shallow water.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a shallow water concrete structure blasting effect test device, comprising a concrete target, a target stress and strain acquisition device, a free-field pressure test device, and a data acquisition system;

[0008] The concrete target is located in the center of the test waters and includes a shell and a concrete structure poured into the shell;

[0009] The target stress and strain acquisition device includes a concrete base block, a stress acquisition rod, and a wall-reflected pressure sensor. The concrete base block is located in the middle of the housing and has a strain sensor on its surface. The stress acquisition rod is equipped with stress sensors located around the concrete base block. The upper end of the stress acquisition rod extends beyond the upper end surface of the concrete structure to determine the direction of the concrete target, placing the target at a predetermined angle and position. The wall-reflected pressure sensor is fixed to the inner wall of the housing.

[0010] The free-field pressure testing device includes a piezoelectric pressure sensor and a support rod. The support rod is arranged outside the concrete target and has a cross-shaped bracket on its upper portion. One end of the piezoelectric pressure sensor is connected to a counterweight, and the other end is connected to and passed around the cross-shaped bracket via a hanging rope. The other end of the hanging rope is provided with a counterweight.

[0011] The strain sensor, stress sensor, wall reflection pressure sensor and piezoelectric pressure sensor are connected to a host computer through a data acquisition system. The data acquisition system is connected to a trigger for controlling the explosion of explosives and is used to receive a time signal when the explosives trigger the explosion.

[0012] Furthermore, the stress collection rod is vertically arranged in the direction of the extension line of the diagonal line of the concrete foundation block.

[0013] Furthermore, at least four stress sensors are provided, corresponding to the side surfaces of the shell respectively.

[0014] Furthermore, a bent rod is connected to the stress collection rod, and an inclined plate is provided at the other end of the bent rod, and the inclined plate is parallel to the side surface of the shell.

[0015] Furthermore, the piezoelectric pressure sensor and the explosive are located at the same height, both at the center of the concrete target.

[0016] Furthermore, the strain sensor is electrically connected to the data collector through a multi-core shielded cable; the stress sensor, the wall reflection pressure sensor, and the piezoelectric pressure sensor are electrically connected to the data collector through a coaxial cable.

[0017] Furthermore, a first strain sensor is provided on the top surface of the concrete base block to output strain information in the X and Y directions; a second strain sensor is provided on the side surface to output strain information in the X and Z directions.

[0018] Furthermore, the explosive is limited by vertical rods welded with a triangular frame to ensure that its explosion position is at a predetermined position.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention realizes standardized data collection and analysis of damage tests under different charge forms and different spatial conditions by constructing concrete targets, stress and strain acquisition devices, and free-field pressure testing devices, which is conducive to summarizing regularities and making reasonable blasting plans.

[0021] The present invention provides a shallow water concrete structure blasting effect test device. The top surface of the concrete base block is provided with a first strain sensor that outputs X- and Y-direction strain information. The side surface is provided with a second strain sensor that outputs X- and Z-direction strain information. This device can analyze whether each surface or part of the target body is subjected to compression failure or tension failure, and whether there is a superposition effect of the explosion shock wave under the influence of the underwater reflection wave and the water surface reflection wave in each damage area.

[0022] The stress collection rod is vertically arranged in the extension direction of the diagonal line of the concrete foundation block, and the stress sensor is installed on the collection rod so that the stress sensors are distributed around the concrete foundation block; the upper end of the stress collection rod extends out of the upper end surface of the concrete structure to determine the direction of the concrete target so that the target is at a predetermined angle and position;

[0023] A cross-shaped bracket is provided on the upper part of the support rod. The first end of the piezoelectric pressure sensor is connected to a hanging rope, and the second end is connected to a first counterweight. The second end of the hanging rope is connected to the cross-shaped bracket and passes around the support rod. The second end of the hanging rope is provided with a second counterweight. When the shock wave arrives, the counterweight is affected by the shock wave and moves simultaneously. Since the upper and lower ends of the sensor are subjected to the same force, the piezoelectric pressure sensor is kept in a relatively stable position before and after the blast, and continuous pressure detection can be performed.

[0024] A triangular frame welded with vertical rods is used to limit the explosives and ensure that they are in the predetermined position in the water. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a shallow water concrete structure blasting effect test device arranged in shallow water according to an embodiment of the present invention;

[0026] Figure 2 yes Figure 1 A top view of

[0027] Figure 3 2. It is a structural diagram of a test device for blasting effects of concrete structures in shallow water shown in an embodiment of the invention;

[0028] Figure 4 is a schematic structural diagram of a concrete target shown in an embodiment of the invention;

[0029] Figure 5 is a schematic structural diagram of a concrete base block shown in an embodiment of the invention;

[0030] Figure 6is a schematic structural diagram of a free-field pressure testing device shown in an embodiment of the invention;

[0031] Figure 7 It is a structural schematic diagram of an explosive placement device shown in an embodiment of the invention;

[0032] Figure 8 is a structural block diagram of a strain data acquisition system shown in an embodiment of the invention;

[0033] Figure 9 is a schematic structural diagram of a strain gauge bridge circuit shown in an embodiment of the invention;

[0034] Figure 10 is a structural block diagram of a wall reflection pressure sensor data acquisition system shown in an embodiment of the invention;

[0035] Figure 11 is a structural block diagram of an underwater pressure sensor data acquisition system shown in an embodiment of the invention;

[0036] In the figure: 10, concrete base block; 11, shell; 12, first strain sensor; 13, second strain sensor; 20, stress sensor; 21, stress collection rod; 203, triangular frame; 204, vertical rod; 30, wall reflection pressure sensor; 40, first data collector; 50, second data collector; 60, piezoelectric pressure sensor; 61, support rod; 62, second counterweight; 100, concrete target; 103, sandbag; 200, explosive; 201, stress collection area; 202, trigger; 300, support pile; 400, data acquisition system. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0038] Combine Figure 1-2 As shown, the present invention proposes a shallow water concrete structure blasting effect test device, including a concrete target 100, a target stress and strain acquisition device, a free-field pressure test device, and a data acquisition system 400. The test device is set in shallow water with a water depth of 1.2-2m.

[0039] In a specific simulation experiment, a long-arm excavator with a 19-meter boom was used to clear the pond bottom silt as far from the shore as possible. During the cleaning process, a depth marker was set up 25 meters from the pass in the pond, and assistants measured the depth of the silt removed as they dug. After the pond bottom was cleared, the excavator excavated the pass backward, gradually increasing the depth along the pond bottom. This formed a gentle slope from the pond edge to the shore, with a depth ranging from 2.0 meters to 1.2 meters and a length of 30 meters.

[0040] Combine Figure 1 As shown, concrete target 100 was placed in the center of the test area, approximately 5 meters from the maximum desilting edge, to avoid the influence of reflected waves from the distant, undrained pond bottom and shore. During underwater testing, the sensor cable needed to be extended from concrete target 100. To prevent damage to the cable during an explosion, cable support piles 300 were installed within the pond. The cable was brought out of the water near concrete target 100 and supported on the shore.

[0041] Furthermore, the cables leading out of the sensors can be pressed to the bottom of the pond by sandbags 103 to reduce the impact of the explosion shock wave.

[0042] The stress collection area 201 of the free-field pressure testing device is arranged with the concrete target 100 as the center and distributed around the concrete target 100 . The stress collection area 201 can be arranged on one side, opposite sides, four sides or diagonal positions of the concrete target 100 .

[0043] Combine Figure 4 As shown, the concrete target 100 includes a shell 11 and a concrete structure poured into the shell 11 , and the shell 11 is configured in a frustum shape.

[0044] Specifically, the target stress and strain acquisition device includes a concrete base block 10, a stress acquisition rod 21 and a wall reflection pressure sensor 30. The concrete base block 10 is located in the center of the shell 11, the stress acquisition rod 21 is located around the concrete base block 10, and the wall reflection pressure sensor 30 is fixed to the middle position of the inner wall of the shell 11.

[0045] Combine Figure 2 As shown, a circular test water area is constructed around the concrete target 100 , the concrete target is located in the center of the test water area, and the stress collection rod 21 is located around the concrete target 100 and in the stress collection area 201 .

[0046] Among them, the concrete base block 10 is set to a rectangular block shape, and four stress collection rods 21 are provided in the extension direction of the diagonal line of the concrete base block. A stress sensor 20 is installed on each stress collection rod 21, and the stress sensors 20 correspond to the four sides of the shell 11.

[0047] Further, combined Figure 3 As shown, a strain sensor is provided on the surface of the concrete base block 10, a stress sensor 20 is provided on the stress collection rod 21, the strain sensor is connected to the host computer through a first data collector 40, and the stress sensor 20, the wall reflection pressure sensor 30 and the piezoelectric pressure sensor 60 are connected to the host computer through a second data collector 50.

[0048] In an alternative embodiment, in combination with Figure 5As shown, a first strain sensor 12 is provided at the center of the top surface of the concrete block 10, and a second strain sensor 13 is provided at the center of the side surface of the concrete block 10. The first strain sensor 12 points to the X and Y directions, and the second strain sensor 13 points to the X and Z directions.

[0049] Furthermore, the concrete base block and the concrete structure are made of the same material.

[0050] The installation method of the strain sensor provided by the present invention is as follows:

[0051] ① Use a water-abrasive grinding wheel to grind the top center (top surface strain) and side center (side strain) of the test specimen;

[0052] ② Grind the strain gauge patch area after water grinding. Grind at a 45° angle according to the direction of the strain gauge. First, use 180-grit sandpaper for rough grinding, and then use 400-grit sandpaper for fine grinding to optimize the surface roughness.

[0053] ③ For the area to be coated with AB glue after polishing, wipe the surface with industrial alcohol to remove loose dust;

[0054] ④ Use a pencil to draw the dividing lines according to the set area;

[0055] ⑤ Apply an appropriate amount of evenly stirred AB glue to the strain gauge patch area and wait for it to solidify;

[0056] ⑥ According to the direction of the strain gauge, cross-grind the AB glue area at a 45° angle, and use 400-grit sandpaper to optimize the surface roughness and thickness of the AB glue.

[0057] ⑦After polishing the AB glue area, wipe it with industrial alcohol to remove dust.

[0058] ⑧ Use 502 glue that dries slowly in 10 seconds to stick the strain gauge and terminal blocks on the patch area; there should be a gap of about 5mm between the strain gauge and the terminal blocks.

[0059] ⑨Use soldering to connect the strain gauge to the terminal, and the terminal to the lead wire;

[0060] ⑩Evenly apply Nanda 703 silicone rubber to the strain gauge area and the wiring area. After 0.5 to 1 hour of applying the silicone rubber, gently press the silicone rubber with your fingertips to remove bubbles. Wait for 24 hours for the silicone rubber to be completely cured.

[0061] The lead-out wire of the sensor is provided with a corrugated tube and is led out of the housing 11 .

[0062] Combine Figure 4As shown, the stress collection rod 21 is provided with a bent rod, and the second end of the bent rod is provided with an inclined plate. The inclined plate is parallel to the side of the shell 11. The inclined plates of the four stress collection rods 21 correspond to the four side surfaces of the shell. The stress sensor 20 is adhered to the surface of the inclined plate by glue to collect the stress exerted on the concrete target 100.

[0063] Preferably, the upper end of the stress collection rod 21 extends out of the upper end surface of the concrete structure and is exposed to the water surface. In this way, the position of the concrete target 100 can be accurately judged on the water surface, so that the concrete target 100 is in the correct predetermined position, which is very important for the test results.

[0064] Furthermore, the wall reflection pressure sensor 30 is tightly connected to the housing 11 through four M4 screws, thereby achieving a firm connection between the reflection pressure sensor and the target.

[0065] Furthermore, a free-field pressure testing device is provided outside the concrete target 100 , and the free-field pressure testing device includes a piezoelectric pressure sensor 60 .

[0066] In an optional embodiment, the concrete base block 10 is fixed to the shell 11 by steel bars. After the stress collection rod 21 and the wall reflection pressure sensor 30 are installed in the shell 11, concrete is poured into the shell 11 to form the concrete target 100.

[0067] Combine Figure 6 As shown, the free-field pressure test device includes a support rod 61 with a cross-shaped bracket mounted on top. A piezoelectric pressure sensor 60 is connected to a hanging rope at its first end, and a first counterweight at its second end. The second end of the hanging rope is connected to the cross-shaped bracket and passes around the support rod. A second counterweight 62 is mounted on the second end of the hanging rope. The counterweights at both ends of the piezoelectric pressure sensor 60 maintain a relatively stable position before and after blasting.

[0068] Preferably, the height of the piezoelectric pressure sensor 60 is the same as that of the explosive 200 , and both are located at the center of the concrete target 100 .

[0069] Furthermore, the first data collector 40 and the second data collector 50 are connected to the trigger 202 for controlling the explosion of the explosive, and are used to receive a time signal when the explosive 200 is triggered.

[0070] Combine Figure 7 As shown, in order to maintain the position of the explosive 200, a triangular frame 203 is welded using a vertical rod 204 to limit the position of the explosive 200, ensuring that its explosion position is at a predetermined position.

[0071] The trigger 202 is used to control the explosion of the explosive 200. When the explosive 200 explodes, the piezoelectric pressure sensor 60 collects the pressure of the external water area, the stress sensor 20 collects the stress on the concrete structure, the strain sensor collects the strain signal received by the concrete structure, and the wall-reflected pressure sensor 30 collects the pressure signal reflected by the wall. The signal is transmitted to the data collector through the signal line and uploaded to the host computer for data analysis and statistics. After many experiments, the explosion effect law of the concrete structure in shallow water can be obtained through data analysis.

[0072] Combine Figure 7 As shown, the stress testing system consists of a stress sensor 20, a coaxial cable, a second data collector 50 (DH5902) and a host computer.

[0073] Combine Figure 8 As shown, the strain testing system consists of a strain gauge, a 4-core shielded cable, a first data collector 40 (DH8302) and a host computer.

[0074] For feasible strain gauges, use BQ120-5AA and BE120-5AA series strain gauges from AVIC Electronics. Figure 9 The 1 / 4 bridge shown in the figure is used to test the strain, using a three-wire connection method, where R1 is the working strain gauge, and the strain gauge sensitivity coefficient is K. The voltage U generated by the bridge circuit is sc With DC supply voltage U sr The relationship between them is:

[0075]

[0076] Combine Figure 10 As shown, the wall reflection pressure test system consists of a wall reflection pressure sensor 30, a coaxial cable, a second data collector 50 (DH5902) and a host computer.

[0077] Combine Figure 11 As shown, the underwater pressure testing system consists of an underwater pressure sensor, a coaxial cable, a second data collector 50 (DH5902) and a host computer.

[0078] In an optional embodiment, the stress and wall reflection pressure sensors are charge output; the underwater pressure sensor is ICP output, and the data acquisition system has a built-in conditioner that can provide a constant current source for the sensor and collect the output voltage of the sensor at the same time.

[0079] Preferably, the multi-core shielded cable and the coaxial cable are suspended above the water surface when outside the stress collection area, thereby reducing the influence of reflected waves from the pond bottom and the shore.

[0080] In combination with the above embodiments, the present invention sets a concrete base block at the center of the concrete target and places strain sensors on the surface of the concrete base block. Unlike the existing method of placing strain sensors on the surface of the concrete structure, the strain data of the target under the action of blasting damage can be detected at the inner center of the target to accurately reflect the strain in various directions inside the target.

[0081] Four stress sensors are set on the outside of the concrete base block inside the concrete to detect the stress data on the four sides of the target. Through real-time monitoring of the stress data, the force conditions at each stage after the blasting moment can be detected. By combining the strain data, the wall reflection pressure sensor and the data of the free-field pressure testing device, it can be obtained whether the pressure at each point is caused by the shock wave or the reflected wave, which is conducive to analyzing the blasting damage mechanism.

[0082] By building concrete targets, stress-strain acquisition devices, and free-field pressure testing devices, data collection and analysis of damage tests under different charging forms and different spatial position conditions can be standardized, which is conducive to summarizing rules and specifying blasting plans.

[0083] The present invention realizes standardized data collection and analysis of damage tests under different charge forms and different spatial conditions by constructing concrete targets, stress and strain acquisition devices, and free-field pressure testing devices, which is conducive to summarizing regularities and making reasonable blasting plans.

[0084] The present invention sets a concrete base block at the center position inside the concrete target and places a strain sensor on the surface of the concrete base block, so as to conveniently detect the strain data of the target under the action of blasting damage through the inner center of the target and accurately feedback the strain of various directions inside the target.

[0085] A stress sensor is set on the outside of the concrete base block inside the concrete to detect the stress data on the side of the target. Through real-time monitoring of the stress data, the force conditions at each stage after the blasting moment can be detected. By combining the strain data, the wall reflection pressure sensor and the data of the free-field pressure testing device, it can be obtained whether the pressure at each point is caused by the shock wave or the reflected wave, which is conducive to analyzing the blasting damage mechanism.

[0086] The present invention can analyze whether each surface or part of the target body is under compression damage or tension damage, and whether the explosion shock wave has a superposition effect under the influence of the bottom reflection wave and the water surface reflection wave in each damage area.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A shallow water concrete structure blasting effect test device, characterized in that: It includes concrete target, target stress and strain acquisition device, free field pressure test device and data acquisition system; The concrete target is located in the center of the test waters and includes a shell and a concrete structure poured into the shell; The target stress and strain acquisition device includes a concrete base block, a stress acquisition rod, and a wall-reflected pressure sensor. The concrete base block is located in the middle of the housing and has a strain sensor on its surface. The stress acquisition rod is provided with stress sensors located around the concrete base block. The upper end of the stress acquisition rod extends beyond the upper end surface of the concrete structure. The wall-reflected pressure sensor is fixed to the inner wall of the housing. The free-field pressure testing device includes a piezoelectric pressure sensor and a support rod. The support rod is arranged outside the concrete target and has a cross-shaped bracket on its upper portion. One end of the piezoelectric pressure sensor is connected to a counterweight, and the other end is connected to and passed around the cross-shaped bracket via a hanging rope. The other end of the hanging rope is provided with a counterweight. The strain sensor, stress sensor, wall reflection pressure sensor and piezoelectric pressure sensor are connected to a host computer through a data acquisition system. The data acquisition system is connected to a trigger for controlling the explosion of explosives and is used to receive a time signal when the explosives trigger the explosion.

2. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: The stress collection rod is vertically arranged in the extension direction of the diagonal line of the concrete foundation block.

3. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: At least four stress sensors are provided, corresponding to the side surfaces of the shell respectively.

4. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: The stress collection rod is connected to a bent rod, and the other end of the bent rod is provided with an inclined plate, and the inclined plate is parallel to the side surface of the shell.

5. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: The piezoelectric pressure sensor and the explosive are located at the same height, and are both located at the center of the concrete target.

6. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: The strain sensor is electrically connected to the data collector through a multi-core shielded cable; the stress sensor, the wall reflection pressure sensor, and the piezoelectric pressure sensor are electrically connected to the data collector through a coaxial cable.

7. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: A first strain sensor is provided on the top surface of the concrete base block to output strain information in the X and Y directions; a second strain sensor is provided on the side surface to output strain information in the X and Z directions.

8. The shallow water concrete structure blasting effect test device according to claim 1, characterized in that: The explosive is limited by a vertical rod welded with a triangular frame to ensure that its explosion position is at a predetermined position.

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