Loaded rock mass internal damage radon exhalation rate response characteristic test device

Abstract

The utility model provides a loaded rock mass internal damage radon exhalation rate response characteristic test device, which comprises a radon measuring instrument and an ultrasonic detector, a radon gas source hole and a plurality of radon airflow observation holes are formed in a rock mass sample, the radon measuring instrument is communicated with the first radon airflow observation hole through a gas inlet pipeline, the radon measuring instrument is provided with an exhaust pipeline, and the radon gas source hole is communicated with the first radon airflow observation hole through a gas outlet pipeline. The radon gas flow observation holes are sequentially communicated through cascade pipelines, the last radon gas flow observation hole is communicated with an air pipeline, the radon gas source hole is used for injecting radon gas in advance to simulate the sealed radon gas in the rock mass, the two ends of the radon gas source hole are detachably connected with sealing plugs, and the ultrasonic detector is connected to different positions of the rock mass sample through an ultrasonic probe. According to the utility model, the complexity of the system and the cumbersome degree of operation are reduced, the complex data acquisition pretreatment work is simplified, the change condition of the radon gas precipitation amount caused by the stress change can be simulated, and whether the radon gas precipitation determination technology can be used as a means for studying the mechanics of the tested rock mass or not can be verified in time.

Description

Technical Field

[0001] The utility model relates to the technical field of rock mass testing, in particular to a test device for radon exhalation rate response characteristics of internal damage of a loaded rock mass. Background Art

[0002] The tunnels (lanes) and work areas formed during underground excavation destroy the stress balance of the original rock in the area, redistribute the stress in the surrounding rock, and form a secondary stress field, which can easily lead to the rupture, displacement, deformation, and even destruction of the surrounding rock on the sides and roof. In particular, the rupture of the rock mass in the high stress concentration area and the instantaneous release of the rapid elastic energy of the rock strata induce ground pressure disasters such as surrounding rock bursting, roof collapse, bottom drum, and wall spalling, which not only reduce the construction efficiency, but also pose a great threat to the safety of construction personnel and equipment, often causing serious engineering problems, and endangering the stable and safe operation of the project after the completion of the project. Therefore, the rapid identification and early warning of the stress failure mechanism of the surrounding rock of the tunnel (lane) and its critical information are the hot spots and difficulties in rock mechanics research.

[0003] Radon is widely distributed in the earth's crust. It is the only naturally occurring radioactive gas element and can be found in almost all kinds of rocks. Radon exists in rocks in the form of free radon, adsorbed radon and enclosed radon. The low porosity of the rock itself not only limits the diffusion of free radon from the rock into the environment, but also makes it difficult for adsorbed radon and enclosed radon to escape from minerals and rocks, thus hindering the precipitation of radon. During the loading and destruction process of rocks, the cracks and surface area of the rocks increase significantly, and many dense microcracks are generated near the cracks. The microcrack network connected inside the rock or mineral increases the porosity and permeability of the rock, allowing free radon to diffuse. Along with the dislocation of the crystal lattice in the rock minerals, bound radon (adsorbed and partially enclosed) is also released.

[0004] There will be obvious changes in radon gas content at different stages of rock deformation and failure, which is closely related to the large increase in rock cracks and surface area during the loading and failure process. By collecting and measuring the concentration of released radon gas, the degree of cumulative damage to the rock mass can be detected. Before collecting data, it is first necessary to sort out parameters such as rock type and size, pressure, loading speed, degree of internal damage to the fracture, and amount of radon gas precipitation, and establish a model for changes in rock fracturing and radon gas migration in pores. Therefore, before measuring the deformation and fracture of a specific rock mass, it is necessary to load the corresponding different rock masses and carry out measurements of the precipitated radon with relevant parameters to provide basic data for specific practical measurements.

[0005] At present, the radon gas detection of the cumulative damage of rock mass is still mostly theoretical research, and there is little research on the changes in the migration of radon gas in the pores and the rock fracturing beforehand. The existing devices and methods are mainly used to determine the optimal parameters of static expansion fracturing of rocks and other materials.

[0006] In the prior art, there is a device and method for real-time monitoring of microwave rock-breaking thermal damage and radon emission. The device includes a microwave heating test chamber, a real-time thermal damage monitoring system, and a host computer. At the same time, there are also a device and method for determining the optimal parameters of static expansion cracking based on multi-source monitoring, which relates to the technical field of determining the optimal parameters of static expansion. The device includes a test chamber, a radon gas measurement component, a confining pressure application component, an ultrasonic detection device, and a laser scanner. In addition, there is also a device for measuring the radon gas release amount during the rock shear failure process and a test method. The test method includes: first, evacuating the sealed chamber installed with the rock mass sample, then collecting all the radon gas released during the shear failure process of the rock mass sample into a radon collection tank, and then using a radon concentration measuring instrument to measure the radon gas concentration collected in the radon collection tank, so as to ensure the purity of the radon gas collected in the radon collection tank, and further ensure the accuracy of the radon gas concentration measured by the radon concentration measuring instrument.

[0007] The overall measurement structure of the devices and methods in the prior art is complex. It may require a special container to seal the sample and a vacuum pumping device to evacuate the container, which is complex in operation and has potential risks. Or it requires a special test chamber, which is bulky in structure and cumbersome in operation, and is not conducive to rapid detection. Utility Model Content

[0008] The purpose of the present utility model is: aiming at the deficiencies in the above-mentioned background technology, to provide a test device with a simpler structure, more convenient operation, and reliable test results.

[0009] To achieve the above purpose, the present utility model provides a test device for the response characteristics of radon emission rate of internal damage in a loaded rock mass, which includes a radon detector and an ultrasonic detector connected to the rock mass sample. The rock mass sample is provided with a radon gas source hole and a plurality of radon gas flow observation holes. The radon detector is connected to the first radon gas flow observation hole through an intake pipe. The radon detector is provided with an exhaust pipe by itself. The radon gas flow observation holes are sequentially connected through a cascade pipe. The last radon gas flow observation hole is connected to an air pipe. The radon gas source hole is used to inject radon gas in advance to simulate the radon gas sealed in the rock mass. Both ends of the radon gas source hole are detachably connected with sealing plugs. The ultrasonic detector is connected to different positions of the rock mass sample through an ultrasonic probe.

[0010] Further, the radon gas source hole is arranged in the middle of the rock mass sample, and the radon gas flow observation holes are arranged at equal intervals on the side of the radon gas source hole.

[0011] Further, the ultrasonic detector is used to obtain two kinds of acoustic information: the acoustic wave time-domain signal, including the sound velocity, the acoustic wave attenuation coefficient, and the maximum amplitude; the acoustic wave frequency-domain signal, including the main frequency, the maximum amplitude, and the energy.

[0012] Further, an air filter cotton is also arranged in the air duct, and the air filter cotton is used for filtering radon daughters in the external air.

[0013] Further, a desiccant is also arranged in the air duct, and the desiccant is used for drying the external air.

[0014] The above solution of the present utility model has the following beneficial effects:

[0015] The test device for the response characteristics of radon emission rate of internal damage in a loaded rock mass provided by the present utility model ensures the sealing of radon gas after injection into the rock mass sample through the setting of the radon gas source hole and the sealing plugs at both ends. The radon gas is automatically pumped in from the radon gas flow observation hole and measured by the radon detector, without the need for additional equipment to evacuate the vacuum, reducing the complexity of the system and the tediousness of the operation. At the same time, the pre-processing work of complex data acquisition is simplified. In addition, the ultrasonic detector is used to perform on-line ultrasonic detection of the rock mass sample, and the change of internal cracks in the rock mass sample is understood in real time according to the pressure size, which can simulate the actual stress change situation and can also verify in time whether the radon emission measurement technology can be used as a means for rock mechanics research;

[0016] Other beneficial effects of the present utility model will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the overall structure of the present utility model.

[0018]

Description of the Reference Numerals

[0019] 1 - Radon detector; 2 - Ultrasonic detector; 3 - Rock mass sample; 4 - Radon gas source hole; 5 - Radon gas flow observation hole; 6 - Intake duct; 7 - Exhaust duct; 8 - Cascade duct; 9 - Air duct; 10 - Sealing plug; 11 - Ultrasonic probe; 12 - Air filter cotton; 13 - Desiccant. Specific Embodiments

[0020] To make the technical problems, technical solutions and advantages to be solved by the present utility model clearer, the following will be described in detail with reference to the drawings and specific embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model. In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0021] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional 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 limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] like Figure 1 As shown, an embodiment of the utility model provides a test device for the response characteristics of radon exhalation rate of internal damage of loaded rock mass. By collecting parameters such as rock mass type, pressure size, loading speed, radon gas exhalation amount and ultrasonic rock mass crack observation, an experiment of measuring the transient response of radon exhalation during rock mass compression change is carried out, the relationship between the mechanical characteristics of the rock mass and the evolution of internal damage of the rock mass during loading is studied, the characteristics such as radon exhalation amount and rate are studied, the damage of the rock mass after stress is understood, the feasibility of the rock mass cumulative damage degree measurement plan is established, and basic comparison data is provided for the actual measurement object.

[0024] The test device includes a radon detector 1 and an ultrasonic detector 2. For a rock sample 3, a radon source hole 4 is opened at the center of the rock sample 3, and multiple radon airflow observation holes 5 are opened at other positions. The radon detector 1 is connected to the first radon airflow observation hole 5 through an air intake pipe 6, and the radon detector 1 itself is provided with an exhaust pipe 7 to connect to the outside world. The radon airflow observation holes 5 are connected in sequence through cascade pipes 8 to form a continuous radon gas passage, and the last radon airflow observation hole 5 is connected to the air pipe 9. The radon source hole 4 is used to inject radon gas in advance to simulate the radon gas sealed in the rock mass. Sealing plugs 10 are provided at both ends of the radon source hole 4. When injecting radon gas, one of the sealing plugs 10 is installed first, and radon gas is injected from the other end of the radon source hole 4. After completion, the other sealing plug 10 is quickly sealed at the other end.

[0025] In this embodiment, the ultrasonic detector 2 is a non-metal ultrasonic detector 2, which can detect the strength, crack depth, damaged layer thickness, internal defects, etc. of non-metals (such as rock masses, concrete, etc.). The ultrasonic detector 2 is connected to different positions of the rock mass specimen 3 through ultrasonic probes 11 for detection. It should be noted that in this embodiment, the ultrasonic detector 2 mainly obtains two kinds of acoustic information: the acoustic wave time-domain signal, including sound velocity, acoustic wave attenuation coefficient, maximum amplitude, etc.; the acoustic wave frequency-domain signal, including main frequency, maximum amplitude, energy, etc.

[0026] As a preferred implementation manner, in this embodiment, an air filter cotton 12 and a desiccant 13 are further arranged in the air duct 9. The radon daughters in the external air are filtered through the air filter cotton 12, so as to ensure that the air entering the radon gas flow observation hole 5 and the radon detector 1 is dry, and to avoid the influence of external radon gas on the test results.

[0027] As described above, the test device for the response characteristics of radon exhalation rate of internal damage of a loaded rock mass provided in this embodiment does not need to be provided with a vacuum pumping device. The radon gas is sealed after being injected into the rock mass specimen 3 through the radon gas source hole 4 and the two end plugs 10. The radon gas is automatically pumped into and measured from the radon gas flow observation hole 5 by the radon detector 1, which reduces the complexity of the system and the cumbersome degree of operation, simplifies the complex data acquisition pre-processing work. In addition, the ultrasonic detector 2 is used to perform on-line ultrasonic detection of the rock mass specimen 3, and the change of internal cracks of the rock mass specimen 3 is understood in real time according to the pressure magnitude. This test device can simulate the actual stress change situation and can also verify in time whether the radon gas exhalation measurement technology can be used as a means for rock mechanics research.

[0028] When using the test device for the response characteristics of radon exhalation rate of internal damage of a loaded rock mass provided in this embodiment for testing, the following steps are included:

[0029] S1, Select drilling rock masses with different volumes, lithologies and structures as specimens. A relatively large radon gas source hole 4 is arranged on the central section of the rock mass specimen 3, and two relatively small radon gas flow observation holes 5 are arranged at equal intervals on both sides of it.

[0030] S2, Before the test, the first end of the radon gas source hole 4 is sealed with a plug 10, and a certain amount of high-concentration radon gas is pumped out from the radon chamber and injected into the radon gas source hole 4.

[0031] S3, After stopping injecting the high-concentration radon gas, quickly seal the second end of the radon gas source hole 4 with another plug 10 to simulate the radon gas sealed in the rock mass.

[0032] S4, Connect the rock mass specimen 3 with the radon detector 1 through a pipeline. A desiccant 13 is arranged at the air inlet position of the radon gas flow observation hole 5 to reduce the humidity of the air, and at the same time, an air filter cotton 12 is arranged to filter the radon daughters in the external air. Turn on the power of the radon detector 1 for preheating.

[0033] S5. Place the rock mass specimen 3 into the press and gradually apply different pressures in time periods to simulate the in-situ stress.

[0034] S6. Since the rock mass specimen 3 has two pairs of mutually parallel test surfaces, the cross-hole method is used for defect detection. After applying the coupling agent on the two pairs of mutually parallel test surfaces, place the transducers at the calibrated measuring point positions for measurement respectively, send a square wave pulse signal of 50 kHz, and record and analyze the measuring point data through the ultrasonic detector 2.

[0035] S7. After applying pressure at different pressure stages and observing the internal defects of the rock mass specimen 3, stop applying pressure, start the radon detector 1, extract the radon gas sample in the radon flow observation hole 5, measure the radon gas emission rate in the radon flow observation hole 5 in the fast measurement mode, and automatically record the measurement data.

[0036] S8. Identify the internal defects of the rock mass specimen 3. The main process is as follows: use the ultrasonic detector 2 to obtain rich acoustic information through two ways, including the acoustic wave time-domain signal and the acoustic wave frequency-domain signal. Among them, the acoustic wave time-domain signal includes the sound velocity, the acoustic wave attenuation coefficient, the maximum amplitude, etc., and the acoustic wave frequency-domain signal includes the main frequency, the maximum amplitude, the energy, etc. Then analyze the cumulative damage degree of the rock mass specimen 3. Based on the data of different pressures, different loading speeds and the cumulative damage degree of the rock mass specimen 3, establish the load-displacement curve, the cumulative damage and fracture curve of the rock mass specimen 3 under different pressures and different loading speeds, etc. Finally, use the number of radon pulses measured during the loading process to draw the relationship diagrams of stress-radon emission rate and stress-volume strain under different pressures and loading speeds. From the response characteristics of the radon emission rate observed during the loading process, combined with the internal damage and fracture development characteristics of the rock mass specimen 3, divide different rock mechanics characteristic stages, so as to establish the connection between the radon emission rate response characteristics and the stress-strain law, the loading speed, and the fracture failure mechanism, and form a characteristic correlation diagram.

[0037] Adopt the test device for the response characteristics of radon emission rate of internal damage of loaded rock mass provided by this embodiment, study the variation law of the radon emission rate response during the stress loading process of the radon gas in the rock mass specimen 3 through experiments, understand the stress-strain characteristics and fracture failure mechanism during the loading process under different pressures and different loading speeds, and obtain the influence of different pressures and different loading speeds on the mechanical properties and radon emission rate. Based on the identification of the internal defects of the rock mass specimen 3 and the radon gas emission amount, speculate on the laws of stress-strain, fracture failure characteristics and radon gas emission during the loading process, analyze the relationship between the radon emission rate response characteristics and the fracture damage evolution process of the rock mass specimen 3, and provide a basis for the judgment of the failure mode and stability analysis of engineering rock mass in the future.

[0038] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0039] The above embodiments only express several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A test device for the response characteristics of radon exhalation rate of internal damage in loaded rock mass, characterized in that: It includes a radon detector and an ultrasonic detector connected to the rock mass specimen. The rock mass specimen is provided with a radon gas source hole and a plurality of radon gas flow observation holes. The radon detector is communicated with the first radon gas flow observation hole through an intake pipeline. The radon detector is provided with an exhaust pipeline itself. The radon gas flow observation holes are sequentially communicated through a cascade pipeline. The last radon gas flow observation hole is communicated with an air pipeline. The radon gas source hole is used to inject radon gas in advance to simulate the radon gas sealed in the rock mass. Both ends of the radon gas source hole are detachably connected with sealing plugs. The ultrasonic detector is connected to different positions of the rock mass specimen through ultrasonic probes.

2. The test device for radon exhalation rate response characteristics of internal damage of loaded rock mass according to claim 1 is characterized in that: The radon gas source hole is arranged in the middle of the rock mass specimen, and the radon gas flow observation holes are arranged at equal intervals on the side of the radon gas source hole.

3. The test device for radon exhalation rate response characteristics of internal damage of loaded rock mass according to claim 1 is characterized in that: The ultrasonic detector is used to obtain two kinds of acoustic information: the acoustic wave time-domain signal, including the sound velocity, the acoustic wave attenuation coefficient and the maximum amplitude; the acoustic wave frequency-domain signal, including the main frequency, the maximum amplitude and the energy.

4. The test device for radon exhalation rate response characteristics of internal damage of loaded rock mass according to claim 1 is characterized in that: An air filter cotton is also arranged in the air pipeline, and the air filter cotton is used to filter the radon daughters in the external air.

5. The test device for radon exhalation rate response characteristics of internal damage of loaded rock mass according to claim 1, characterized in that: A desiccant is also arranged in the air pipeline, and the desiccant is used to dry the external air.

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