Tunnel earthquake advanced forecasting seismic source based on chemical anchor bolt coupling

Abstract

The utility model relates to a tunnel earthquake advanced forecasting seismic source based on chemical anchor bolt coupling, which is characterized in that a cylindrical threaded through hole coupling device is arranged on the outer wall of a pneumatic seismic source, the cylindrical threaded through hole coupling device is connected with a telescopic bracket, a metal bottom sheet is arranged at the end part of the telescopic bracket, and the metal bottom sheet is connected with the pneumatic seismic source. A through hole matched with the chemical anchor bolt is formed in the metal bottom sheet, and the pneumatic vibration source is coupled and fixed on a tunnel wall through the chemical anchor bolt. The tunnel earthquake advanced forecasting device has the advantages that tunnel earthquake advanced forecasting is carried out by adopting a method of coupling a pneumatic seismic source as a seismic source and a chemical anchor bolt, the safety can be greatly improved in a tunnel construction site, the tunnel earthquake advanced forecasting device and other works can be carried out at the same time, the time of other engineering operations cannot be delayed, and the time cost is reduced; the pneumatic vibration source is more miniaturized, the transportation cost is reduced, and the portability is improved; and the chemical anchor bolt is provided with threads, so that the chemical anchor bolt is relatively high in connection strength and relatively good in expansibility, and can be combined with various structures.

Description

TECHNICAL FIELD

[0001] The utility model relates to tunnel construction advance prediction technical field, concretely relates to a tunnel earthquake advance prediction seismic source based on chemical anchor bolt coupling. BACKGROUND

[0002] Tunnel earthquake advance prediction technology is a kind of technology that predicts adverse geological body possibly existing in front of tunnel face in the process of tunnel construction.This technology is very important for preventing geological disasters in tunnel construction, such as collapse, gushing, rock burst, etc., and also has an important influence on the progress of tunnel construction. At present, the seismic source used in tunnel earthquake advance prediction mainly includes explosive seismic source and non-explosive seismic source.

[0003] The basic principle of explosive seismic source is to use the high-temperature and high-pressure gas produced by explosive explosion to form shock wave to work on the outside, so as to excite seismic wave. But since explosive is a controlled product, it needs to be approved and operated by professional people when used, which brings great inconvenience to advance prediction work. Explosive seismic source uses the shock wave of explosive explosion, which has safety hazards in construction, and the implementation time is relatively long. In terms of transportation portability, although the volume of explosive required for one detection is small, explosive can only be transported by special transportation method, which greatly limits the portability of transportation.

[0004] At present, the seismic method based on non-explosive seismic source is more and more valued by engineering field. Among them, mechanical seismic source, electric spark seismic source and pneumatic seismic source are more superior. The advantage of mechanical seismic source is that the waveform and frequency of effective wave produced are controllable within a certain range, high resolution, wide azimuth and high density data acquisition can be realized in the process of exploration, and the environment is less damaged. The main shortcomings are as follows: high technical threshold and cost, poor environmental adaptability, high requirement for operator's professional level. Electric spark seismic source is a kind of non-explosive seismic source technology, which converts electric energy into pulse force to produce seismic wave, and is widely used in fields such as seismic exploration, petroleum, coal field and engineering seismic exploration. This kind of seismic source has the characteristics of simple structure, convenient operation and high automation. The main shortcomings are as follows: it needs to be matched with drilling in the process of use, it is difficult to impact the tunnel wall, and the volume and weight are large.

[0005] The pneumatic seismic source is to compress air, accumulate energy, release the compressed air to the hammer head when the energy reaches the required level, and transfer the energy of the compressed gas to the hammer head. From the perspective of energy conversion, it is a mechanical energy conversion process which is controllable and safe. And the high-pressure gas is converted into mechanical energy in principle only by the cylinder, and the power supply and air pump can be directly borrowed from the conditions in the construction tunnel, which is of low quality and portable in the construction tunnel. However, the pneumatic seismic source needs to impact the tunnel wall in the tunnel, and the strong recoil force generated by the impact makes it difficult to fix the seismic source when the mass of the pneumatic seismic source is small, and it is difficult to generate effective high-energy seismic wave signals.

[0006] Chinese invention CN202110058949.7 discloses a hydraulic servo controllable seismic source for tunnel advance prediction. The device is too large to enter the tunnel, and has poor practicality. It cannot complete the work when it needs to impact the wall.

[0007] Chinese invention CN202111551679.X discloses a multipurpose seismic exploration vacuum seismic source system and working method. It is similar to explosive seismic source, so the shortcomings of this patent are similar to those of explosive seismic source. Moreover, the device needs to completely wrap the explosion source, increasing the manufacturing cost and difficulty.

[0008] Chinese invention CN202321684249.X discloses a controllable hydrogen seismic source for seismic exploration. The device can greatly reduce the risk of hydrogen explosion, but the explosion source hydrogen is very dangerous and difficult to transport, making it difficult to achieve popularization. Its practicality is greatly discounted.

[0009] The existing technologies including the above inventions mainly have the following shortcomings:

[0010] 1) Energy level and frequency: The most fundamental requirement in tunnel seismic advance prediction is the energy level and frequency of the seismic source. Only by meeting these two requirements can the detection purpose be achieved and the accuracy of detection be ensured. For example, the energy and frequency of some small drop hammer seismic sources are not enough, and the seismic wave generated by them is completely distorted when used for detection, which cannot meet the prediction requirements.

[0011] 2) Poor mobility: When conducting advance prediction in a tunnel, seismic waves need to be generated at multiple points. The weight and size of the controllable seismic source equipment are large, and the tunnel environment is complex, making it difficult to move in the tunnel. It cannot meet the needs of tunnel advance prediction.

[0012] 3) Safety: The explosive seismic source itself poses a certain threat to the safety of construction personnel.

[0013] 4) Time cost and economic benefits: Heavy seismic sources are expensive, explosive seismic sources require drilling during use, which takes up time, and seismic source vehicles are expensive to manufacture, so the time cost and economic benefits are relatively high.

[0014] 5) Inability to impact tunnel walls: Currently, most mechanical seismic sources cannot directly impact vertical tunnel walls, thus failing to meet the requirements for tunnel advance prediction.

[0015] 6) Environmental protection: Explosive explosions release harmful chemicals that pollute the air, soil and water, causing long-term impacts on the ecological environment. The noise pollution generated is also not to be ignored. Summary of the Invention

[0016] The purpose of this invention is to address the shortcomings of the existing technology by providing a tunnel earthquake early prediction source based on chemical anchor coupling. This invention is based on a non-explosive source and uses a pneumatic source as the source, coupled with the tunnel through chemical anchors. This solves two major problems in tunnel earthquake early prediction: mobility and energy requirements. It also performs well in other aspects such as portability, safety, environmental protection, economic benefits, and time cost.

[0017] The objective of this utility model is achieved through the following technical solution:

[0018] A tunnel seismic advance prediction source based on chemical anchor coupling includes a pneumatic source with an impact hammer. The pneumatic source is characterized by having a cylindrical threaded through-hole coupling device on its outer wall, which is connected to a telescopic support. A metal base plate is located at the end of the telescopic support plate, and the metal base plate has through holes matching the chemical anchor. The pneumatic source is fixed to the tunnel wall via the chemical anchor coupling.

[0019] The metal base plate is connected to a bracket, which is located inside the telescopic bracket and extends and retracts at the telescopic bracket. The telescopic bracket has a fixing hole.

[0020] The bottom of the telescopic bracket is equipped with a metal triangular support frame.

[0021] The pneumatic vibration source is equipped with a fast pressure relief valve.

[0022] The advantages of this utility model are:

[0023] 1) The method of using a pneumatic source as the source and chemical anchor bolt coupling is used for tunnel earthquake early prediction. Compressed gas is used instead of explosives, which can greatly increase safety at the tunnel construction site. It can be carried out simultaneously with other work without delaying other engineering operations and reducing time costs.

[0024] 2) The pneumatic vibration source is more miniaturized, with a weight controllable to around 30kg, allowing a single adult male to perform the corresponding operation. The heaviest component of the entire system, the air pump, can be a local air pump used on-site, reducing transportation costs and increasing portability.

[0025] 3) Chemical anchors are more convenient to use than drilling holes in explosive seismic sources. Explosive seismic sources require deep holes to ensure effective wave transmission, and reagents must be added inside the holes to increase energy utilization. However, chemical anchors can be fixed by a single person using a hand drill. In poor geological conditions, multiple sets of chemical anchors can be used for reinforcement. Chemical anchors have built-in threads, resulting in high connection strength and good expandability, allowing for combination with various structures. Compared to explosive seismic sources, chemical anchors are significantly cheaper. Attached Figure Description

[0026] Fig. 1 This is a schematic diagram of the structure of this utility model;

[0027] Fig. 2 This is a detailed structural diagram of the telescopic bracket in this utility model;

[0028] Fig. 3 This is a schematic diagram of the aerodynamic vibration source in this utility model. Detailed Implementation

[0029] The features and other related features of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate the understanding of those skilled in the art:

[0030] like Figs. 1-3 As shown in the figure, the labels represent: 1. Metal base plate, 2. Telescopic bracket, 3. Metal triangular support base, 4. Pneumatic vibration source, 5. Impact hammer, 6. Cylindrical threaded through hole coupling device, and 7. Quick release valve.

[0031] Example: Figs. 1 to 3 As shown, in this embodiment, the tunnel earthquake early prediction source based on chemical anchor coupling can be divided into two parts: the base part and the source part. The base part is mainly composed of chemical anchors, metal base plate 1, telescopic bracket 2, and metal triangular support base 3, while the source part is a pneumatic source 4.

[0032] Combination Figs. 1 to 3 As shown, in this embodiment, the outer wall of the pneumatic vibration source 4 is provided with several cylindrical threaded through-hole coupling devices 6, which enable a detachable connection between the pneumatic vibration source 4 and the telescopic support 2. The pneumatic vibration source 4 has an impact hammer 5, which is used to impact the tunnel wall. A quick-release valve 7 for venting air is provided on the vibration source 4.

[0033] In this embodiment, the internal structure of the pneumatic vibration source 4 can be divided into two chambers, A and B. Chamber A is used for air intake to achieve reset and recovery. Chamber B is used for air intake to store energy. A baffle is used to isolate the two chambers and is connected to the impact hammer 5. The following steps are repeated: Chamber A is used for air intake and reset. After maintaining air intake and energy storage for 2-3 seconds, Chamber A is exhausted, and Chamber B continues to intake air to achieve the impact of the impact hammer 5.

[0034] Telescopic supports 2 are respectively installed on both symmetrical sides of the pneumatic vibration source 4. A metal base plate 1 with a support is installed at the end of the telescopic support 2. The support of the metal base plate 1 is embedded inside the cavity of the telescopic support 2, allowing the support to extend or retract relative to the telescopic support 2, thereby adjusting the distance between the pneumatic vibration source 4 and the tunnel wall. Fixing holes are provided on the telescopic support 2 for relative fixation between the metal base plate 1 with the support and the telescopic support 2, ensuring the structural stability of the support.

[0035] A through hole matching the chemical anchor is provided on the metal base plate 1; when the chemical anchor is installed on the tunnel wall, the metal base plate 1 can be quickly and fixedly connected to the chemical anchor through its reserved through hole, thereby completing the installation and fixation between the overall support and the tunnel wall.

[0036] A metal triangular support base 3 is provided at the bottom of the telescopic support 2 to further improve the connection strength and stability between the overall support and the tunnel wall. In this embodiment, the metal triangular support base 3 can also be fixed to the tunnel wall using chemical anchors.

[0037] When using this embodiment, the following steps are included:

[0038] 1) First, use a hand drill to make three to four holes about eight centimeters deep at the locations in the tunnel wall where impact is required (the drilling depth should be adjusted according to the geological conditions of the tunnel wall). Drive the chemical anchors into the holes according to the correct usage method and wait one minute for the chemical anchors to be fully coupled with the tunnel wall. After full coupling, connect the metal base plate 1 to the threaded end of the chemical anchor through a threaded connection to form a stable coupling between the support and the tunnel wall.

[0039] 2) The telescopic support 2 is telescopic to adjust the distance between the pneumatic vibration source 4 and the tunnel wall to achieve the best impact effect. The pneumatic vibration source 4 and the fixed telescopic support 2 are connected by a cylindrical threaded through-hole coupling device 6. That is, the pneumatic vibration source 4 is placed on the telescopic support 2 at the reserved position, and the reserved through hole between the two is connected by bolts.

[0040] 3) When it is necessary to move to the next impact point, first unscrew the bolts between the pneumatic vibrator 4 and the telescopic bracket 2, then disconnect the threaded connection between the metal base plate 1 and the chemical anchor, and repeat the above operation with the overall bracket and the chemical anchor at the next point. Therefore, the pneumatic vibrator 4 has strong mobility in the construction tunnel, ensuring that its weight is within 30kg when vibration occurs at multiple points, making it easy to move portablely in the construction tunnel. The remaining chemical anchors are inexpensive and will not affect the project, so no treatment is required.

[0041] In this embodiment, a 120-frame imaging device is used to freeze each frame, and the energy is calculated based on the mass and stroke of the impact hammer 5. In terms of energy magnitude, the impact hammer 5 of the pneumatic vibrator 4 has a mass of 8 kg. After the air pressure in the air chamber reaches the standard value, the pneumatic vibrator 4 is activated, and the impact hammer 5 undergoes accelerated motion. The acceleration time is short and can be estimated as uniform acceleration motion. The hammer's stroke is 200 mm, and the motion time is 0.01 s. This is under a 7 MPa air pump pressure; using a larger-specification air pump can further increase the energy.

[0042] According to the work-energy theorem:

[0043]

[0044] The energy of the aerodynamic seismic source 4 can be calculated to be approximately 6400 J. In tunnel earthquake early warning systems, explosive seismic sources, which are widely used, typically have a charge of around 20g, generating 80kJ of energy upon detonation. However, the energy utilization rate of explosive seismic sources is low, only 3%. Aerodynamic seismic sources, on the other hand, have an energy utilization rate of approximately 50%, producing seismic wave energy of approximately 2400 J, and thus an effective energy of approximately 3200 J. Comparing the two, the aerodynamic seismic source is sufficient to meet the requirements.

[0045] The estimated contact time between the hammer and the wall is approximately 2000N. The frequency and energy level of the seismic waves generated by the designed seismic source need to meet industry standards to ensure the accuracy of tunnel advance prediction and sufficient detection range.

[0046] The relevant parameters of chemical anchors are shown in the table below:

[0047] Table 1 shows the specifications of chemical anchors.

[0048]

[0049] Table 2 shows the load-bearing capacity of chemical anchors (unit: kN).

[0050]

[0051] The load-bearing capacity of chemical anchors is far greater than that of impact force, and the support structure is fully capable of withstanding the recoil force of the seismic source.

[0052] The advantages of using this embodiment are:

[0053] 1) Chemical anchor coupling technology: In this embodiment, chemical anchors are used to couple with the tunnel wall to securely install the aerodynamic source, and the source is connected to the steel pipe through the thread of the chemical anchor to achieve a stable coupling between the source and the tunnel wall.

[0054] 2) Application of pneumatic vibration sources: Using pneumatic vibration sources instead of traditional explosive vibration sources improves construction safety and allows the coupling between the vibration source and the tunnel wall to be movable, so as to adapt to the dynamic needs during tunnel construction.

[0055] 3) Mobility design of the seismic source: By drilling holes in the tunnel wall along a straight line and installing chemical anchors, and then connecting the pneumatic seismic source through these anchors, the mobility of the seismic source is achieved to meet the needs of earthquake prediction in different locations.

[0056] 4) Solutions for different geological conditions: For situations with poor geological conditions, this embodiment provides two solutions: one is to lengthen the chemical anchors to increase the coupling strength, and the other is to improve the connection strength by using rectangular iron plates and increasing the number of chemical anchors.

[0057] 5) Safety and portability: The pneumatic vibration source design in this embodiment is miniaturized, making it easy for a single person to operate. It can also utilize the air pump at the construction site, reducing the need for equipment transportation and increasing portability.

[0058] 6) Cost-effectiveness: The use of chemical anchors not only improves construction efficiency, but also has a lower cost compared to explosive sources, and does not cause physical damage to the tunnel structure.

[0059] 7) Environmental adaptability: The technical solution of this embodiment allows other engineering operations to be carried out simultaneously during tunnel construction without having to stop other work due to earthquake prediction, thereby saving time and costs.

[0060] 8) Telescopic device: The telescopic device is used to control the distance between the hammer and the tunnel wall, so that the energy efficiency of the pneumatic vibration source can be maximized, and energy loss can also be reduced and the service life of the device can be improved.

[0061] 9) Triangular bracket: Due to the long overall length of the aerodynamic source, a large lever will be generated when it is fixed on the tunnel wall. Adding a triangular bracket can not only greatly reduce the lever force, but also share the reaction force during impact.

[0062] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A seismic source for tunnel seismic advance prediction based on chemical anchor coupling, comprising a pneumatic source, wherein the pneumatic source is equipped with an impact hammer, characterized in that: The outer wall of the pneumatic vibration source is provided with a cylindrical threaded through-hole coupling device, which is connected to a telescopic bracket. The end of the telescopic bracket is provided with a metal base plate, and the metal base plate has a through hole that matches the chemical anchor. The pneumatic vibration source is coupled and fixed to the tunnel wall through the chemical anchor.

2. The tunnel seismic advance prediction source based on chemical anchor coupling according to claim 1, characterized in that: The metal base plate is connected to a bracket, which is located inside the telescopic bracket and extends and retracts at the telescopic bracket. The telescopic bracket has a fixing hole.

3. The tunnel seismic advance prediction source based on chemical anchor coupling according to claim 1, characterized in that: The bottom of the telescopic bracket is equipped with a metal triangular support frame.

4. The tunnel seismic advance prediction source based on chemical anchor coupling according to claim 1, characterized in that: The pneumatic vibration source is equipped with a fast pressure relief valve.

Images