CN-122017146-A - Surrounding rock grouting effect evaluation system and method based on radon gas monitoring

CN122017146ACN 122017146 ACN122017146 ACN 122017146ACN-122017146-A

Abstract

The invention discloses a surrounding rock grouting effect evaluation system and method based on radon gas monitoring, and relates to the field of surrounding rock grouting effect evaluation. The system comprises a radon gas monitoring system and a laboratory device, wherein the radon gas monitoring system comprises a monitoring grouting anchor rod and a radon measuring assembly, the monitoring grouting anchor rod is provided with a plurality of monitoring grouting anchor rods, each monitoring grouting anchor rod comprises a hollow rod body and three air extraction rods which are embedded in the hollow rod body in parallel, a grouting hole is formed in the wall of the hollow rod body, the tail end of each air extraction rod can be opened and closed, the air outlet ends of the three air extraction rods are fixedly arranged at the tail end of the hollow rod body, the air inlet ends of the three air extraction rods are correspondingly positioned in the range of an elastic zone, a plastic zone and a crushing zone of surrounding rock, the radon measuring assembly comprises radon measuring instruments, and the laboratory device is a triaxial pressure experimental device. According to the invention, on-site actual measurement and experimental analysis are combined, the radon gas separation concentration of multiple points is synchronously monitored on site and compared with a critical characteristic threshold value, and the grouting effects at different depths in the rock stratum are inverted by radon gas concentration distribution characteristics, so that the system is convenient to operate, high in system monitoring efficiency and high in data reliability.

Inventors

ZHANG WEI
ZHAO LEILEI
WANG JINGCHENG
ZHANG DONGSHENG
YANG FEILI
FAN WEITAO
WANG YANPENG
MA LIQIANG
MAO JINFENG
TANG JIEBING

Assignees

中国矿业大学
新疆工程学院

Dates

Publication Date: 20260512
Application Date: 20260213

Claims (10)

1. The surrounding rock grouting effect evaluation system based on radon gas monitoring is characterized by comprising a radon gas monitoring system and a laboratory device; The radon monitoring system comprises a monitoring grouting anchor rod (2) and a radon measuring assembly (4); the monitoring grouting anchor rods (2) are arranged in a plurality, each monitoring grouting anchor rod (2) comprises a hollow rod body (21) and three air suction rods which are embedded in the hollow rod body (21) in parallel, grouting holes (214) are formed in the pipe wall of the hollow rod body (21), the tail ends of the three air suction rods can be opened and closed, the air outlet ends of the three air suction rods are fixedly arranged at the tail ends of the hollow rod body (21), the air inlet ends of the three air suction rods are correspondingly positioned in the range of an elastic zone, a plastic zone and a crushing zone of surrounding rock (1), a first sealing sleeve (212) and a second sealing sleeve (213) for isolating different monitoring sections are sleeved outside the hollow rod body (21), an inflation sealing rod (26) is arranged in the hollow rod body (21) in parallel to the air suction rods, a third sealing sleeve 261 and a fourth sealing sleeve 262 are fixed on the inflation sealing rod (26), the axial positions of the third sealing sleeve 261) and the fourth sealing sleeve 262 correspond to the first sealing sleeve 212 and the second sealing sleeve 213, the air inlet ends of the three air suction rods are correspondingly positioned in the elastic zone, the plastic zone and the crushing zone of the surrounding rock (1), the first sealing sleeve (261) and the second sealing sleeve (262) are correspondingly positioned on the wall of the surrounding rock (1), the air meter is integrally provided with a sealing assembly (263) at the position of the end of the air meter, and the sealing assembly (4) is provided with a sealing joint, and the sealing assembly is provided with a sealing joint (263), the radon measuring instrument is communicated with the air suction rod through a pipeline, and the laboratory device is a triaxial pressure experimental device.
2. The surrounding rock grouting effect evaluation system based on radon gas monitoring as claimed in claim 1 is characterized by further comprising a centralized control box (3), wherein the centralized control box (3) comprises gas path control units (31) and a central controller (32), the gas path control units (31) are correspondingly provided with a plurality of groups of monitoring grouting anchor rods (2), the gas path control units (31) are arranged on pipelines connected with radon measuring instruments through gas extraction rods, a group of gas path control units (31) are shared by pipelines connected with tail ends of three gas extraction rods in each monitoring grouting anchor rod (2), each gas path control unit (31) comprises an electromagnetic valve (314), a vacuum pump (315) and a filter (316), and the central controller (32) uniformly controls each gas path control unit (31) and is in communication connection with the radon measuring assembly (4) through signal lines (33) so as to allocate measurement flows and automatically record concentration data.
3. The surrounding rock grouting effect evaluation system based on radon gas monitoring as claimed in claim 1 is characterized in that the air suction rod and the inflatable sealing rod (26) are fixed and arranged in parallel through a narrow-side clamping groove (218) embedded in the hollow rod body (21), a grouting stop plug (217) is sleeved outside the tail end of the monitoring grouting anchor rod (2), an openable protective end cover (211) is fixedly arranged at the tail end of the monitoring grouting anchor rod (2), the inside of the openable protective end cover (211) is hollow, and the top end of the openable protective end cover is flush with the tail end of the air suction rod.
4. The surrounding rock grouting effect evaluation system based on radon gas monitoring as claimed in claim 1, wherein grouting holes (214) on the hollow rod body (21) are partitioned into three groups corresponding to three different surrounding rocks (1), and each group of grouting holes (214) is uniformly distributed with a plurality of grouting holes along the circumference of the hollow rod body (21).
5. The surrounding rock grouting effect evaluation system based on radon gas monitoring according to claim 1, wherein three radon detectors are arranged and correspondingly connected with three air extraction rods in each monitoring grouting anchor rod (2) through pipelines.
6. The surrounding rock grouting effect evaluation system based on radon gas monitoring as claimed in claim 1 is characterized in that the laboratory device comprises a triaxial test machine (5), a test piece (6), a fourth radon measuring instrument (8) and a computer (9), the triaxial test machine (5) comprises a triaxial pressure chamber (54), an axial pressurizing rod (51), a test piece cap (52) and a base (53), the test piece (6) is placed in the triaxial pressure chamber (54), hydraulic oil (541) is further arranged in the triaxial pressure chamber (54) and used for providing surrounding pressure for the test piece (6), the test piece (6) is arranged between the test piece cap (52) and the base (53), the test piece cap (52) is arranged between the axial pressurizing rod (51) and the test piece (6), a high-pressure cabin penetrating connector (531) penetrating through the base (53) is arranged at the center of the base (53), the fourth radon measuring instrument (8) is connected with an outlet cabin of the high-pressure cabin penetrating through a rubber pipe (533), the high-pressure cabin penetrating through the rubber pipe (533) is further provided with a porous membrane (532), and the porous membrane (532) is fixedly arranged at the upper end of the porous membrane (532) and is in contact with the porous membrane (532).
7. A method for performing grouting effect evaluation by using the radon gas monitoring-based surrounding rock grouting effect evaluation system according to any one of claims 1-6, comprising the following steps: s1, in an on-site region to be measured, obtaining a complete compact core to prepare a test piece (6) and sending the test piece to a laboratory; S2, installing the test piece (6) in a triaxial tester (5), applying set confining pressure to simulate lateral constraint stress born by the triaxial tester in situ, and continuously loading the test piece (6) axially to the test piece (6) for damage, wherein the axial stress-strain and radon gas concentration data precipitated by the test piece (6) are synchronously and continuously collected in the whole process; S3, calculating a damage variable D (t) of each time point based on stress-strain data, pairing the D (t) with radon concentration C (t) at the same time to obtain a series of data points (D, C), and performing curve fitting to obtain a complete C-D characteristic relation curve; S4, analyzing a characteristic relation curve to determine a characteristic radon concentration inflection point representing critical transition of the damage state of the surrounding rock (1), measuring the on-site in-situ radon background concentration corresponding to a laboratory threshold C 1 、C 2 , and calibrating the characteristic radon concentration threshold by combining the indoor rock sample background radon concentration to obtain an on-site engineering threshold A, B suitable for the current engineering site; S5, arranging monitoring grouting anchor rods (2) in the surrounding rock (1), grouting, controlling an air path control unit (31) and a radon measurement assembly (4) through a central controller (32) after the grouting and the solidification of the grouting are carried out, continuously pumping air from different depth monitoring points inside the monitoring grouting anchor rods (2) in sequence, and recording radon concentration; S6, comparing the radon gas concentration value R of each measuring point measured in the step S5 with the field engineering threshold value obtained in the step S4, wherein if the measured concentration value R is less than or equal to A, the grouting effect of the area where the measuring point is located is judged to be excellent, if A is less than or equal to R is less than or equal to B, the grouting effect of the area where the measuring point is located is judged to be good, and if R is less than or equal to B, the grouting effect of the area where the measuring point is located is judged to be unqualified.
8. The method of claim 7, wherein in S3, the damage variable D (t) corresponding to different loading moments is calculated by using a model based on elastic modulus degradation, wherein D (t) =1-E (t)/E 0 , wherein E 0 is an initial elastic modulus, E (t) is a secant modulus at moment t, the initial elastic modulus E 0 is determined by a slope of an initial straight line segment of the stress-strain curve of the test piece (6), and the secant modulus E (t) is determined by a slope of a line connecting the stress-strain data point at moment t to the origin.
9. The method of claim 7, wherein in S4, the characteristic radon concentration inflection points include inflection positions where the slope of the curve corresponding to the first inflection point (D 1 ,C 1 ) increases gradually to increase sharply, and inflection positions where the slope of the curve corresponding to the second inflection point (D 2 ,C 2 ) increases sharply and then decreases, and radon concentration values C 1 and C 2 corresponding to the two inflection points are laboratory thresholds, and meanwhile, an average value C field1 、C field2 、C field3 of radon concentrations before grouting at monitoring points in the monitoring grouting anchor rod (2) is used as an in-situ radon background concentration in the field, radon concentrations C lab1 、C lab2 、C lab3 corresponding to the test piece (6) d=d 1 /2、D=(D 1 +D 2 )/2、D=(D 2 +1)/2 are extracted from experimental data respectively as laboratory radon background concentrations, and then a field calibration factor k= (C field1 ＋C field2 ＋C field3 )/(C lab1 +C lab2 +C lab3 ) is calculated to obtain the field engineering threshold value a=k×c 1 ,B=k×C 2 .
10. The method of claim 7, wherein in S5 the anchor rod installation method comprises the steps of: S51, drilling holes at the designed positions of surrounding rock (1), inserting the hollow rod body (21) with the assembled anchor head (22) into the drilled holes, sleeving a grout stop plug (217) and a backing plate (215) in sequence, and screwing nuts (216) to enable the backing plate (215) to press a rock surface; S52, opening an openable protective end cover (211) at the tail end of the hollow rod body (21) to inject slurry into the hollow rod body (21), and allowing the slurry to seep out from the grouting holes (214) and fill the drilling space and the surrounding rock (1) cracks; S53, immediately injecting high-pressure gas into the hollow rod body (21) to perform rod cleaning operation, discharging slurry which possibly blocks the air suction rod and the grouting holes (214), and then closing the openable protective end cover (211); S54, when the grout is fully solidified, opening an openable protective end cover (211) and a closable inflation interface (263), inflating the inside of an inflation sealing rod (26) to enable a third sealing sleeve (261) and a fourth sealing sleeve (262) to generate radial uniform expansion, tightly wrapping an air suction rod in the same section by the expanded sealing sleeves, tightly attaching the air suction rod with the inner wall of a hollow rod body (21) of a monitoring grouting anchor rod (2), thereby forming an effective physical isolation sealing strip inside the hollow rod body (21), closing the closable inflation interface (263) after inflation is completed, connecting one end of a pipeline to the tail part of the air suction rod, and connecting the other end of the pipeline to a corresponding radon measuring instrument; S55, an internal electromagnetic valve (314) of a gas circuit control unit (31) on a control pipeline of a central controller (32) is opened, a corresponding vacuum pump (315) is started, radon gas at each measuring point in the same monitoring grouting anchor rod (2) is extracted, the gas is sent to a radon measuring component (4) through a filter (316) to carry out multi-measuring-point synchronous radon concentration measurement, measurement data are returned in real time through a signal line (33), the central controller (32) automatically binds and stores a data set with information corresponding to anchor rod numbers and measuring point numbers, and then the system automatically carries out measurement of the next monitoring grouting anchor rod (2), so that radon gas inside the multi-monitoring grouting anchor rod (2) can be synchronously and continuously monitored.

Description

Surrounding rock grouting effect evaluation system and method based on radon gas monitoring Technical Field The invention relates to the technical field of surrounding rock grouting effect evaluation, in particular to a surrounding rock grouting effect evaluation system and method based on radon gas monitoring. Background In the tunnel and tunnel engineering, surrounding rock grouting is a key technology for reinforcing broken rock bodies and plugging cracks to improve the bearing capacity of the surrounding rock, and the accurate evaluation of grouting effect is directly related to the long-term stability of supporting safety engineering. Radon gas is used as a serial decay product of uranium radium, and is an inert gas, and migration of radon gas is mainly controlled by permeability of surrounding rock cracks and pores. When the surrounding rock is damaged due to mining and cracks develop, the permeability of the surrounding rock is enhanced, the radon gas precipitation flux is obviously increased, otherwise, the effective grouting can fill the cracks, the porosity of the surrounding rock is reduced, and the radon gas precipitation is inhibited. Therefore, the radon gas concentration can be used as a natural and sensitive trace index for representing the opening and closing and communication states of the cracks in the surrounding rock, and a physical foundation is laid for realizing accurate evaluation of grouting effect. The rock mechanics knowledge shows that the surrounding rock damage has obvious zoning characteristics, and a crushing zone, a plastic zone and an elastic zone are sequentially formed from the surface to the inside, and the crack development degree and grouting effect of each zone are obviously different, so that the permeation and solidification effects of the slurry in different zones are also different. However, the existing grouting effect evaluation method (such as drilling coring, sonic testing and the like) mostly regards drilling holes or monitoring points as a homogeneous whole, and cannot realize isolation grading evaluation of different damaged areas in the same drilling hole, so that the evaluation result is rough and accurate identification of grouting weak parts is difficult, and secondly, the existing monitoring means are mostly single-point and discrete measurement, so that efficient, continuous and automatic monitoring of a plurality of monitoring points in the whole tunnel or tunnel section cannot be realized, the efficiency is low, and the distribution rule of grouting effects is difficult to master in space. Therefore, a method and a system for realizing partition, synchronization and efficient grouting effect evaluation by coupling a surrounding rock damage mechanism and radon migration rules are needed, so that scientific and quantitative evaluation from 'point' to 'face' of the surrounding rock grouting effect is realized. Disclosure of Invention Aiming at the problems, the invention discloses a surrounding rock grouting effect evaluation system and method based on radon gas monitoring, which combines on-site actual measurement with experimental analysis, synchronously monitors the radon gas separation concentration of multiple points on site and compares the radon gas separation concentration with a critical characteristic threshold value, inverts grouting effects at different depths in a rock stratum by radon gas concentration distribution characteristics, and has the advantages of convenient operation, high system monitoring efficiency and strong data reliability. According to the invention, the surrounding rock grouting effect evaluation system based on radon gas monitoring comprises a radon gas monitoring system and a laboratory device; The radon gas monitoring system comprises a monitoring grouting anchor rod and a radon gas measuring assembly, wherein the monitoring grouting anchor rod is provided with a plurality of monitoring grouting anchor rods, each monitoring grouting anchor rod comprises a hollow rod body and three air extraction rods embedded in the hollow rod body in parallel, the pipe wall of the hollow rod body is provided with a grouting hole, the tail end of the hollow rod body can be opened and closed, the air outlet ends of the three air extraction rods are fixedly arranged at the tail end of the hollow rod body, the air inlet ends of the three air extraction rods are correspondingly positioned in the range of an elastic zone, a plastic zone and a crushing zone of surrounding rock, the first sealing sleeve and the second sealing sleeve for isolating different monitoring sections are sleeved outside the hollow rod body, an air inflation sealing rod is arranged in the hollow rod body in parallel to the air extraction rods, a third sealing sleeve and a fourth sealing sleeve are fixed on the air inflation sealing rod, the axial positions of the third sealing sleeve and the fourth sealing sleeve correspond to the first sealing sleeve and the secon