Introduction

The continuous high intensity consumption of human beings all year round leads to the gradual depletion of shallow easily mined resources, and mineral development has inevitably moved to the depth direction1,2. The increasing depth of underground coal mining, will inevitably lead to further damage to the strata, and the multi-factor coupling effect of its occurrence environment (such as high stress, high ground temperature, high depth, high osmotic pressure, strong compression, strong mining, and strong aging characteristics) restricts the continuous, safe and efficient mining of mineral resources to a great extent. Deep wells are facing more severe mining problems. Rock burst, coal and gas herniation, mining induced earthquake, and other dynamic disasters occur frequently, so it is extremely urgent to accurately predict dynamic disasters in mining engineering3. Domestic and foreign experts have explored the causes of different dynamic disasters as comprehensively as possible, and combined with the specific circumstances of different dynamic disasters, many commonly used and mature monitoring methods have been formed. Taking rock burst as an example, the specific monitoring methods include the microseism method, acoustic emission method, electromagnetic radiation method, CT method, coal stress method, and drilling cuttings method4,5,6. Through literature review, it can be found that the above monitoring conclusions are often mainly qualitative or semiquantitative parameters, and the monitoring data still need to be reliably identified and analyzed by observers. At present, some scholars have introduced the ²²²Rn measurement method into the coal mine field. A large number of studies show that the diffusion behavior of ²²²Rn in the emanative medium is an aging process related to internal and external factors such as temperature, pressure, water content, porosity, and permeability7,8,9and domestic and foreign experts have made a detailed analysis of the above mentioned factors affecting ²²²Rn diffusion, which has been well popularized in the identification of spontaneous combustion areas in coal mines10,11. In the aspect of rock burst prediction, its essence is to monitor the damage evolution of loaded rocks.

Considering that the research on blasting mechanism is mature at present, periodic blasting means can not only crush adjacent rocks, but also cause continuous damage to the retained rock mass, and the evolution law of blasting damage cracks has been systematically studied12,13,14. Therefore, with the help of cyclic blasting load, this paper tries to monitor the dynamic process of rock damage evolution by using the abnormal index of ²²²Rn exhalation rate, to construct a new quantitative ²²²Rn exhalation rate damage analysis method and provide the theoretical basis for the subsequent multiangle accurate prediction of rock burst.

Currently, there are two main methods of uranium mining in the world: leaching of uranium and conventional uranium mining. Compared with conventional uranium mining, the leaching of uranium takes most advantages of the natural impregnability of uranium and has the advantages of low production cost and small labor intensity15. In practical engineering, the leaching of uranium was used more, and can be subdivided into three major technologies: in situ leaching of uranium, in situ blasting, and leaching of uranium and surface heap leaching of uranium. However, the method of acid, alkali, or CO2 + O2 neutral leaching in the process of in situ leaching has a certain degree of blocking problem of the ore layer16,17. In addition, in situ blasting and leaching of uranium and surface heap leaching of uranium are inevitable to use periodic blasting methods. Not only can the adjacent rock be broken, but also can cause sustained damage to the retained rock mass. During blasting excavation of uranium ore roadway, first of all, in the vicinity of blasting, the blasting effect of explosives on rocks caused direct impact damage, resulting in roadway surrounding rock damage. Secondly, in the middle and far area of blasting, with the excavation of the roadway, the cumulative damage effect of periodic blasting vibration on the surrounding rock will lead to the propagation of microcracks in the early stage of blasting, which will inevitably affect the ²²²Rn exhalation rate of uranium rock, the concentration of ²²²Rn and its daughters was over18,19.

For uranium mines, ²²²Rn radiation protection is particularly important20. At present, mechanical ventilation is the main measure to reduce the concentration of ²²²Rn and ²²²Rn in uranium mining21. But when designing a ventilation ²²²Rn removal system in a uranium mine mountain, the first thing to consider is the amount of ²²²Rn in the mine environment from the radioactive medium, and the amount of ²²²Rn in the radioactive medium is affected by the diffusion of ²²²Rn in the medium22. A large number of studies show that the diffusion of ²²²Rn in radioactive gas medium is an aging process related to temperature, pressure, moisture content, porosity, permeability, and other internal and external factors. Domestic and foreign experts have analyzed the above factors of ²²²Rn diffusion in detail, but the study on the damage evolution and ²²²Rn exhalation characteristics of uranium rocks under cyclic blasting load is still blank 20,21,22. Therefore, it is necessary to design a continuous ²²²Rn detecting device for cumulative damage of uranium ore to obtain experimental data and obtain the relationship between cumulative damage characteristics of uranium ore and cyclic ²²²Rn exhalation rate under cyclic blasting load. A theoretical basis can be provided for the prevention and control of ²²²Rn. We hypothesize that the exhalation rate of ²²²Rn can serve as a reliable indicator for cumulative damage in uranium-bearing rocks caused by cyclic blasting.

Methods

²²²Rn (Rn) is a chemical element and usually in the form of ²²²Rn gas. ²²²Rn gas is the only radioactive inert gas to which humans come into contact. Under normal conditions, it is colorless, tasteless, and soluble in water. With a half-life of 3.82d, the diffusion ability is strong. Because ²²²Rn gas is radioactive, even small concentrations can be detected. At the same time, It also has the geophysical and chemical properties of inert gas, which can be transmitted and accumulated in micropores or microcracks23. Therefore, it is widely used in the field of detection.

In the field of engineering geology, ²²²Rn gas measurements have been widely used in geological prospecting efforts to find uranium, conduct geological mapping, detect hidden structures, find bedrock groundwater and geothermal heat, and look for oil and gas24,25,26. In the field of coal mine safety, ²²²Rn gas has been widely used in the location of coal seam spontaneous combustion areas. In the field of comprehensive detection, ²²²Rn gas has been widely used in surface detection of overburden rock mining induced fractures and their water content27.

During the actual mining of uranium ore, the effect of continuous periodic (cyclic change of rock blasting load) changed the rock mass within the original stress condition, and stimulated the internal crack rock mass through, development, which led to cumulative damage of rock mass, and thus easy to increase the production of radioactive ²²²Rn gas, seriously restricting the rock uranium mining. Through literature retrieval, found that so far no radioactive ²²²Rn gas utilization of features to detect the loop uranium ore rock under blasting load crack extending and its dynamic research concerning the cumulative damage. For this reason, the research group has carried out pioneering basic research and exploration, mainly based on the following three principles28:

(1) Under normal temperature and pressure conditions, ²²²Rn gas can escape from uranium ore formation and can migrate through micro-pores and microfracture networks inside the rock mass.

(2) The break and damage evolution of uranium ore rocks can significantly increase the diffusion speed and distance of radioactive ²²²Rn gas, and the ²²²Rn concentration will be different with different damage densities.

(3) Uranium rock damage under cyclic blasting load can be reversed through surface detection of the variation rule of radioactive ²²²Rn exhalation rate of uranium rock under cyclic blasting load.

Experimental design and procedures

To be able to conduct experiments under indoor laboratory conditions and provide an analytical basis for subsequent data processing, a comprehensive test system was designed for the study of the cumulative damage evolution law and ²²²Rn exhalation rate characteristics of uranium-like rocks under cyclic blasting loads. The comprehensive test system is primarily constituted for four major components: the simulation test apparatus, the cyclic blasting load application apparatus, the cumulative damage degree measurement apparatus, and the radioactive ²²²Rn gas detection apparatus. It possesses the merits of facile disassembly and assembly during construction and overcomes the drawbacks of traditional physical simulation test systems, such as complexity, cumbersomeness, and singletest functionality.

Simulation test set

The simulation test unit is a core unit of the integrated test system. To avoid the blasting shock wave damage to the inner wall, the blasting container around the key parts of the blasting container drilling some screw holes and configure a number of bolts, the upper surface of the blasting container and the blasting container base for fixing, to buffer the effect of the blasting shock wave.

The simulation test set is designed to use a blasting vessel with a thickness of 10 mm, type 304 stainless steel as the material, and internal dimensions of L × W × H = 270 mm x 270 mm x 250 mm. To ensure that the uranium-like rock test block can be placed in the center of the blasting container, the bottom of the blasting container open the test block bottom area of the size of the groove, to ensure that the bottom of the test block and the groove complete fit. In addition to this, the blasting containers are used as hermetically sealed ²²²Rn collectors when radioactive ²²²Rn gas is detected in the test blocks, so the air tightness of the blasting containers is also ensured. The appearance of the unit is shown in Fig. 1.

Fig. 1
figure 1

Appearance of simulation test device. Created using SolidWorks 2021 (Dassault Systèmes, https://www.solidworks.com/).

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Cyclic blast load applying device

The cyclic blast load application device is a core unit of the integrated test system. In the center of the upper surface of the prepared test block along the thickness of the direction of the drilled holes, in the center of the drilled holes in the arrangement of explosives, and fill the holes with moist loess, through the control of the amount of charge, the primer head detonation, the implementation of several small dosage blasting. The device simulation is shown in Fig. 2.

Fig. 2
figure 2

Simulation diagram of cyclic blasting load application device. Created using SolidWorks 2021 (Dassault Systèmes, https://www.solidworks.com/). based on our own model designs.

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Cumulative damage measuring device

The Cumulative Damage Measurement Unit is a core unit of the integrated test system. A nonmetallic ultrasonic detector was used to determine the acoustic wave velocity of the specimen. To avoid the flatness of the surface of the test block from affecting the measurement data, butter was used as the coupling medium during the measurement process, thus ensuring a close fit between the probe and the test block. As shown in Fig. 3.

Fig. 3
figure 3

Schematic diagram of cumulative damage degree measuring device. Created using SolidWorks 2021 (Dassault Systèmes, https://www.solidworks.com/). based on our own model designs.

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Before and after the action of blasting, in the location of the key points (the selection of key points to the location of explosives as the baseline, sequentially spaced 4 cm for the arrangement), the use of a nonmetallic ultrasonic detector to measure the initial wave velocity of the test piece as well as the wave velocity of the test piece after blasting. Whereas the measured value is the acoustic wave velocity value, it needs to be converted to the desired cumulative damage value.

Radioactive ²²²rn detection devices

The radioactive ²²²Rn gas detection device is a core unit of the integrated test system. Blasting containers are used in integrated test systems not only as conventional blasting containers, but also as airtight collection chambers for radioactive ²²²Rn gas. The airtightness of the device is ensured by laying a thick layer of rubber cushion between the upper surface of the blasting container and the base of the blasting container, which is compacted using a plurality of bolts. The RAD7 continuous ²²²Rn meter is proposed to be used in this test. The measurement process is shown in Fig. 4.

Fig. 4
figure 4

Schematic diagram of radioactive ²²²Rn detection device. Created using SolidWorks 2021 (Dassault Systèmes, https://www.solidworks.com/). based on our own model designs.

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Before each ²²²Rn measurement, aluminum foil is used to wrap the upper and bottom surfaces of the test block, as well as one set of symmetrical surfaces around the test block, and only the other set of symmetrical surfaces is exposed. Measure its cumulative ²²²Rn concentration before and after blasting using the RAD7 continuous ²²²Rn meter, and calculate the radioactive ²²²Rn gas exhalation rate.

The uncertainty of ²²²Rn exhalation rate was evaluated following the approach from Zhou et al.31. The uncertainty sources include the ²²²Rn concentration over time (σC), the volume of the chamber (σV), and the surface area of the chamber bottom (σS). As the same ²²²Rn detector and chamber were used in all experiments, the volume and area remained constant. The RF was first calculated using the simplified formula with C₀ ≈ 0, and the uncertainty (σRF) was subsequently derived using the method. The RAD7 detector employed in this work was previously calibrated at the University of South China ²²²Rn Laboratory, with an accuracy within ± 5%.

Experimental process

The experiment is carried out by injecting gunpowder into the borehole, pulling out a fuse, and then placing the test block as a whole in an iron box and igniting the fuse to carry out the blast. Before blasting, all test points should be numbered (top to bottom, left to right totaling 25 test points) and recorded, and then the first acoustic wave velocity test should be carried out to detect the distribution of acoustic wave velocities in the test blocks and to determine the extent of established test block damage and disturbance. After each blast, the test block was instrumented for acoustic wave velocity measurements, keeping the transmitting and receiving probes parallel at all times during the measurement. After the wave velocity measurement, the test block was placed back in the iron box for ²²²Rn gas concentration measurement. The experiment was carried out until the test block produced a rupture.

Calculated inversion based on theoretical values of ²²²rn exhalation rates

The Confined Cavity Method is to place a uranium-like rock test piece after relevant pretreatment measures have been carried out in a confined environment, and estimate the ²²²Rn exhalation rate of the uranium-like rock test piece by measuring the ²²²Rn concentration inside the confined environment that changes over time, and calculating the diffusion length and the intrinsic ²²²Rn exhalation rate. The difference between the two types of pretreatments (exposed one end or both ends) results in a different distribution of internal ²²²Rn concentration, so the relationship between the measured ²²²Rn exhalation rate and the intrinsic ²²²Rn exhalation rate of the uranium-like rock test block is completely different. For this reason, this paper is based on the research theory of Guo Qiuju and others30and based on the different parceling methods constructed corresponding to the different ²²²Rn exhalation rate models for subsequent detailed analysis.

  1. (1)

    Porosity and particle density \({\rho _0}\);

Porosity can be measured by water absorption [1] and the density changes with it. Firstly, put the test piece of uranium ore rock to be tested into the constant temperature drying oven, the temperature is set at 110℃, and dry it completely until the mass remains constant, at this time, record the mass of \({m_{dry}}\); secondly, soak the test piece in water completely for 24 h and then take it out and weigh it, and wait for it to be saturated with fully absorbed water, at this time, record the mass of \({m_{wet}}\).

The porosity \(\eta\), and particle density \({\rho _0}\) are calculated as:

$$\eta =\frac{{{m_{wet}} - {m_{dry}}}}{{{\rho _w}V}}\:{\rho _0}=\frac{{{m_{dry}}}}{{V\left( {1 - \eta } \right)}}=\frac{\rho }{{1 - \eta }}$$
(1)

where V is the volume of the specimen (m³); \({\rho _w}\)is the density of water at room temperature (g·cm3); \(\rho\) is the dry density (g·cm3).

(2) 226Ra (Chemistry) CRa;

The 226Ra content of the test blocks was determined by acid melting radioactive gas scintillation. The experimental samples were uranium-like tailings test pieces. The main method is to knock the sample and grind it to powder form and then mix it with aqua regia to make a solution, use microwave digestion to ablate and melt the sample solution, cool it down, enclose the dissolved liquid in a diffuser to accumulate ²²²Rn, and then transfer it to the scintillation chamber, and then read the data of the ²²²Rn activity concentration through the FD 125 ²²²Rn and Thoron Analyser and the FH 463B type auto-calibrator, and then calculate the 226Ra content according to the relevant formulae.

$${C_{Ra}}=\frac{{k\left( {{n_2} - {n_1}} \right)}}{{2w\left( {1 - {e^{ - \lambda t}}} \right)}}$$
(2)

where k is the scale value of the scintillation chamber (Bq/counts·min⁻¹); n is the count measured in the scintillation chamber; w is the sample mass (g); t is the counting time (min); \(\lambda\) is the effective decay constant of ²²²Rn.

(3) Injection coefficients \({S_e}\);

The empirical formula for the injection coefficient \({S_e}\) is:

$${S_e}=\frac{{{I^{{t_x}}} - {I^{{t_1}}}}}{{\left( {{I^{{t_x}}} - {I^{{t_1}}}{e^{ - \lambda \left( {{t_x} - {t_1}} \right)}}} \right){e^{ - \lambda {t_1}}}}}$$
(3)

where \(I^{t_{1}}\) and \(I^{t_{x}}\) are the net counts at the same characteristic peak at sealing times \({t_1}\)and\({t_1}\).

(4) Pore diffusion coefficient of ²²²Rn Dk;

RAD7 was used to determine the cumulative ²²²Rn concentration in each group of specimen blocks and thus to obtain the apparent diffusion coefficient of ²²²Rn in the specimens.

The test block wrapping schematic is shown in Fig. 5. Aluminum foil was used to wrap the test block to reduce ²²²Rn loss during detection.

Fig. 5
figure 5

Package picture.

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The pore diffusion coefficient Dk for ²²²Rn is calculated as:

$${D_k}=D\eta$$
(4)

where Dk is the pore diffusion coefficient of ²²²Rn; D is the pore coefficient of radon; \(\eta\) is the porosity.

To simulate the calculation, the pore diffusion coefficient of ²²²Rn Dk, dry density ρ, 226Ra content \({C_{Ra}}\), shot gas coefficient \({S_e}\), porosity \(\eta\), and height \({\text{h}}\) obtained were combined with the formula and finally calculated to get the theoretical value of ²²²Rn exhalation rate of uranium-like rocks E, which was finally deformed as:

$${E_0}=\sqrt {\lambda \eta D} \frac{{{C_{Ra}}{S_e}{\rho _0}}}{\eta }=\sqrt {\lambda {D_k}} \frac{{{C_{Ra}}{S_e}\rho }}{{\eta \left( {1 - \eta } \right)}}$$
$$E=D\frac{d}{{d{\text{x}}}}{C_{\left| {x=0} \right.}}=({E_{\text{0}}} - \sqrt {\lambda \eta D} {C_0}){\text{tanh(}}\sqrt {\frac{{\lambda \eta }}{D}} h{\text{)}}={\text{[}}\sqrt {\lambda {D_{\text{k}}}} \frac{{{C_{Ra}}{S_e}\rho }}{{\eta \left( {1 - \eta } \right)}} - \sqrt {\lambda \eta D} {C_0}]{\text{tanh(}}\sqrt {\frac{{\lambda \eta }}{D}} h{\text{)}}$$
(5)

In Eq. (5): The relevant symbols have the same meaning as above.

Preliminary application of comprehensive test equipment

The Confined Cavity Method is to place a uranium-like rock test piece after relevant pretreatment measures have been carried out in a confined environment, and estimate the ²²²Rn exhalation rate of the uranium-like rock test piece by measuring the ²²²Rn concentration inside the confined environment that changes over time, and calculating the diffusion length and the intrinsic ²²²Rn exhalation rate. radioactive ²²²Rn concentration changes under the cyclic blasting load. The experimental flow chart is shown in Fig. 6.

Fig. 6
figure 6

Experimental flow chart.

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Preparation of Uranium-like rock

According to the preparation technology of the uranium-like rock similar to materials that the current applicant’s team has mastered, an orthogonal test is carried out to make a plurality of test blocks. After the curing is completed, relevant physical and mechanical parameters are measured to obtain the density of the rock sample and the 226Ra content, porosity, radioactivity, compressive strength, and other parameters. Make sure to be similar to the uranium ore sample, and then obtain the optimum ratio of similar materials for the uranium-like rock block test, and prepare the test block of the uranium ore rock with the length × width ×thickness = 250 mm×250 mm×200 mm.

Preparation for blasting

The steel blasting container is made of 201 steel plates with a thickness of 10 mm, the length × width × height = 270 mm × 270 mm × 250 mm (inner diameter), the prepared test block is placed in the middle position of the selfmade blasting container, Drill holes in the thickness direction (φ = 4 mm, h = 120 mm).

Implementation of blasting process

During the single blasting, 0.25 g of black gold is placed in the central borehole, and the stemming hole is sealed. To avoid the boundary effect, a layer of thick butter is applied around and filled with fine sand around the test block. Use detonator ignition gunpowder detonation, the implementation of the blasting process, and the impact of small doses of repeated cycles of blasting load.

Cumulative damage degree

Before and after a single blasting, the key point locations (the key points were selected around the four weeks centerline, followed by the interval of 5 cm arrangement), the use of nonmetallic ultrasonic testing instrument initial velocity of rock samples, and rock mass velocity after a single blasting, Converted to a single degree of blasting damage. The formula (6) is as follows:

$${S_n}=1 - {\left( {\frac{{{V_n}}}{{{V_0}}}} \right)^2}$$
(6)

where \({S_n}\) is the cumulative damage degree after the n-th blasting (dimensionless): \({V_0}\)is the acoustic velocity of the test block before blasting (m·s-1);\({V_n}\) is the acoustic velocity of the test block after the n-th blasting (m·s-1).

Comprehensive cumulative damage degree

Due to the limitations of nonmetal ultrasonic detector, a single blasting measurement showed 25 blasting damage value, it is difficult to determine after blasting comprehensive damage, so this paper uses the K-means clustering algorithm, which uses distance as the similarity evaluation index of the two objects that the distance closer, the greater the similarity.

The specific process of the basic algorithm is as follows:

(a)Select K data from the blast damage data file as the centroid;

(b)Measure the distance to each centroid for each of the remaining data and assign it to the nearest centroid class;

(c)Recalculate the centroid of each class that has been obtained;

(d)Iteration 2 ~ 3 steps until the new centroid and the original centroid are equal to or less than the specified threshold, the algorithm ends.

Closed chamber method for ²²²rn measurement

To effectively avoid measurement error, it is proposed to use a closed chamber method, so the homemade blasting container is a ²²²Rn collection device, taking into account the upper surface of the blasting vulnerable surface (there will be some damage, the surface area increased ²²²Rn exhalation Distortion), to analyze the process of internal damage through the process, that is, single blasting aluminum foil wrapping the relevant surface, exposed four weeks symmetrical double surface, using RAD7 ²²²Rn meter to measure the cumulative ²²²Rn concentration before and after blasting, and using the software directly obtained to be Combined with inclined line k, calculate the ²²²Rn exhalation rate before and after single blasting. The formula (7) is as follows:

$${J_n}=\frac{{{k_n} \cdot V}}{S}$$
(7)

where \({J_n}\)is the ²²²Rn exhalation rate of the test block after the n-th blasting (Bq·m⁻²·s⁻¹);\({k_n}\) is the slope of the accumulated ²²²Rn concentration curve for the test block after n blastings (Bq·m⁻³·s⁻¹); \(k_{n}\) is the exposed surface area of the test block (m²); V is the effective volume outside the test block within the ²²²Rn collection device (m³).

Results and discussion

To better analyze the evolution law of cumulative damage29, the cumulative damage value of each test point is calculated with second blasting as an example, and the change curve is drawn, as shown in Fig. 7. The image curve can reveal the law: from the angle of each row (each column), the damage value calculated by each test point is symmetrically arranged at the horizontal (vertical) angle relative to the third row (third column).

Fig. 7
figure 7

The Curve of damage value at each measurement point in the second blasting.

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Based on the above rules, the relationship between the cumulative damage evolution and ²²²Rn exhalation rate under cyclic blasting load is studied and analyzed. The cumulative damage degree of the cumulative damage was calculated by K-means cluster analysis, and the ²²²Rn exhalation rate was obtained by the closed chamber method, which was based on the correlation between the two. The curves of the cumulative damage degree and the ²²²Rn exhalation rate the number of blasting times were drawn, as shown in Fig. 8.

Fig. 8
figure 8

Curve image between integrated cumulative damage and ²²²Rn exhalation rate and blasting times.

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Fig. 9
figure 9

Function relationship fitting.

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Fit the curve of ²²²Rn gas ejection rate versus the number of blasts, as shown in Fig. 9. Fitting results show that there is a positive correlation between the damage evolution of radioactive rock and the ²²²Rn exhalation law under cyclic blasting load, and through this experiment, a large number of basic experimental data have been obtained, and the correlation between the damage degree of radioactive rock and the ²²²Rn exhalation rate has been obtained, there is a strong linear correlation between the ²²²Rn exhalation rate and cumulative damage of rock samples in the elliptical region. Therefore, based on the above experimental analysis results, an attempt is made to put forward a prediction index K for describing the change of ²²²Rn exhalation rate in the process of damage evolution of radioactive rock under cyclic blasting load, and the expression defining K is:

$$K={{({J_n} - {J_0})} \mathord{\left/ {\vphantom {{({J_n} - {J_0})} {{J_0}}}} \right. \kern-0pt} {{J_0}}} \times 100\%$$
(8)

It can be seen from Formula (8) that the greater the measured ²²²Rn exhalation rate, the greater the prediction index K, indicating a higher damage degree in radioactive rock under cyclic blasting load. This is because microcracks and pores formed during damage increase the radon diffusion pathways. Assuming external interference is excluded, K can be used as a sensitive indicator for internal damage evolution 31, 32.

Based on experimental results, when K exceeds 9.8%, the rock mass reaches a damage limit, suggesting the presence of significant deterioration or even macrocracks. This threshold provides a preliminary criterion for judging critical damage. Moreover, a continuously rising K value may serve as a real-time early warning for structural failure in field applications.

However, the 9.8% threshold is based on laboratory conditions. To enhance its applicability, further research is needed to verify its effectiveness under in-situ environments and to establish damage classification standards based on K ranges.

Conclusions

This study confirms the hypothesis proposed in the introduction: the exhalation rate of ²²²Rn can serve as a reliable indicator of cumulative damage in uranium-bearing rocks subjected to cyclic blasting loads. By establishing a quantitative relationship between cumulative damage and ²²²Rn exhalation, and proposing a new prediction index K, this research provides a scientific basis for using ²²²Rn as a non-invasive damage monitoring tool in uranium mining environments. The main findings are as follows:

(1) The first attempt is made to introduce the radioactive measurement method into the cumulative damage detection of uranium ore rock under the cyclic blasting load, which has innovated a simpler, more rapid, and reliable detection method and also broadened the application field of ²²²Rn detection technology.

(2) The continuous ²²²Rn gas exploration uranium rock cumulative damage test device developed by the research group has the advantages of easy disassembly and assembly, and can successively complete the blasting simulation and collection and detection of ²²²Rn on the same device.

(3) The simulation of cumulative damage evolution and the corresponding law of ²²²Rn exhalation rate obtained by the device simulation further verified the feasibility of using ²²²Rn to detect cumulative damage.