Drilling, grouting and filling method for multi-layer old goaf

Abstract

The invention discloses a drilling, grouting and filling method for a multi-layer old goaf. The method comprises the steps that S1, drilling construction is conducted; s2, a grouting pipe is installed; s3, adjusting the concentration of the slurry; s4, performing pressure flushing; s5, grouting in different areas; s6, performing slurry overflowing treatment; and S7, the grouting effect is detected. According to the drilling, grouting and filling method for the multi-layer old goaf, the drilling technology that one hole penetrates through multiple layers is adopted, the construction period can be shortened, a traditional orifice pipe pouring technology is replaced with the annular air bag plugging technology, sealing of a grouting pipe and the hole wall is achieved, and then the slurry proportion is dynamically adjusted according to the fracture development degree; grouting is conducted in different areas according to the sequence of deep first, shallow first and bottom first, grouting parameters are dynamically adjusted, the filling effect and the engineering quality are improved, the grout emitting rate is greatly reduced, meanwhile, grout is prepared through industrial solid waste, and green and efficient treatment of the goaf is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mine safety, in particular to a multi-layer old goaf drilling and grouting filling method. Background Art

[0002] During mining activities, multi-layer old goafs form complex layered collapse zones and fracture zones due to repeated mining of coal seams. The internal rock mass is broken and the voids are unevenly distributed, which can easily cause continuous deformation of the overburden and surface subsidence, seriously threatening the safety of ground transportation infrastructure, industrial plants and other construction projects.

[0003] Traditional layered grouting treatment technology requires repeated drilling, pouring of orifice pipes and segmented grouting for each goaf, which has the following defects: 1. Multiple drilling and pouring of orifice pipes extend the construction period; 2. The static slurry ratio is difficult to match the permeability differences of fracture zones of different depths, resulting in insufficient local filling rate; 3. Traditional orifice pipes rely on cement consolidation and sealing, and are prone to circumferential crack slurry under dynamic grouting pressure, reducing filling efficiency.

[0004] Therefore, it is urgent to develop an efficient and precise grouting method that is suitable for the complex structure of multi-layer goaf areas to improve filling uniformity and engineering reliability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the existing defects and provide a multi-layer old goaf drilling grouting filling method. The drilling process of one hole penetrating multiple layers is adopted, which can shorten the construction period, and replace the traditional hole pipe casting process with the annular airbag sealing technology to achieve the sealing of the grouting pipe and the hole wall. The slurry ratio is dynamically adjusted according to the degree of development of the cracks, and the grouting is carried out in the order of "deep first, shallow later, bottom first, top later" to achieve dynamic adjustment of the grouting parameters, improve the filling effect and project quality, and greatly reduce the grouting rate. At the same time, industrial solid waste is used to prepare slurry to achieve green and efficient management of goaf, which can effectively solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a multi-layer old goaf drilling grouting filling method, comprising the following steps: S1. Drilling construction: Mark the hole location and drill with a 127mm drill bit. When the drill bit penetrates the loose soil layer and enters the stable bedrock for ≥6m, promptly insert a 114mm steel pipe to protect the wall. Subsequently, replace the drilling tool with a 91mm diameter and continue drilling downward using an 89mm drill bit. The drill bit is allowed to successively penetrate the target multi-layer goaf and finally drill to the collapse zone below the lowest goaf or at least 2m below the stable coal seam floor, thus completing the grouting hole drilling operation. S2. Grouting pipe installation: After the grouting hole is drilled, the hole must be thoroughly cleaned and inspected. Only after confirming that the hole is clean and free of debris can the Ø50mm grouting pipe be lowered. First, a rubber pad is placed between the grouting pipe and the hole wall. Then, a flange is installed on the side of the grouting pipe above the rubber pad to prevent grouting. Finally, an annular airbag is installed on the side of the grouting pipe on the flange and inflated to achieve dynamic sealing between the hole wall and the grouting pipe. Finally, clean water is injected to conduct a sealing test. S3. Slurry concentration adjustment: Dynamically adjust the water-solid ratio based on the target goaf and surrounding rock fissure development degree obtained from drilling revelations and previous exploration data to adapt to the permeability and filling requirements of different areas; S4. Pressure flushing: Before the formal grouting operation, the grouting holes and the target voids in the holes or the pores in the rock formation that may be connected should be fully flushed with pressurized water to remove blockages such as rock powder and debris and improve the injectability of the grout. When intermittent grouting is required, intermittent water pressure operation should be carried out in time during each pause in grouting to maintain the grouting channel unobstructed and prevent the grouting pipeline from being blocked during the next grouting due to sedimentation and consolidation of the slurry. S5. Zoned grouting: Grouting is performed at intervals to avoid slurry cross-layering. The slurry is diluted first and then thickened. The diluted slurry is injected first to displace the air inside the goaf, and then the slurry concentration is adjusted step by step. The grouting pressure is dynamically adjusted according to the void ratio of the fracture zone in the goaf. Under the final pressure condition, the grouting volume is ≤70L / min and the injection is stopped after 15-20 minutes. The final hole pressure is 1-3MPa. S6. Grouting treatment: When grouting occurs at the orifice, reduce the pressure to 0.5-1MPa, flow rate ≤30L / min and grout intermittently. If it is ineffective, reinstall the air bag until the grouting operation is completed; S7. Grouting effect detection: 6 months after construction, drill holes at representative goaf locations or locations where abnormalities occurred during construction to conduct full-hole core sampling to directly observe the slurry filling in the goaf, and evaluate the treatment effect by combining the stone core compression test and in-hole TV observation. As a preferred technical solution of the present invention, As a preferred technical solution of the present invention, in S1, a rotary drill or a percussion drill is selected for drilling according to the geological conditions.

[0007] As a preferred technical solution of the present invention, in S1, after the drilling construction is completed, it is necessary to ensure that the hole inclination error of the grouting hole is strictly ≤1° / 100m.

[0008] As a preferred technical solution of the present invention, in S2, the internal working pressure of the annular airbag should be maintained in a constant range of 0.02-0.03 MPa after it is inflated.

[0009] As a preferred technical solution of the present invention, in S3, the fracture development zone uses cement fly ash slurry with a water to cement fly ash ratio of 1:1.3, and the cement fly ash slurry contains 2% accelerating agent, and the dense zone uses cement fly ash slurry with a water to cement fly ash ratio of 1:1.1-1.2.

[0010] As a preferred technical solution of the present invention, in S4, when performing water pressure operation, the flushing pressure is 80% of the grouting pressure and is not greater than 1Mpa; the single flushing time is 5-10min, and when the orifice leakage is observed to be greater than 100L / min, the flushing can be stopped.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The multi-layer old goaf drilling and grouting filling method exemplified in the present invention adopts a "one hole through multiple layers" drilling process, combined with annular airbag dynamic sealing technology, to replace the traditional layered orifice pipe casting, reduce the drilling amount, and shorten the construction period.

[0012] The multi-layer old goaf drilling and grouting filling method exemplified in the present invention adjusts the water-solid ratio in real time according to the degree of fissure development, ensuring that the filling rate of different areas can be effectively improved.

[0013] The multi-layer old goaf drilling grouting filling method exemplified in the present invention adopts an airbag-flange double sealing system to achieve dynamic sealing between the grouting pipe and the hole wall, which can effectively reduce the grouting rate and quickly deal with residual grouting through an intermittent pressure reduction grouting mechanism.

[0014] The multi-layer old goaf drilling and grouting filling method exemplified in the present invention adopts a drilling process of one hole penetrating multiple layers, which can shorten the construction period, and replace the traditional hole pipe casting process with the annular airbag sealing technology to achieve sealing between the grouting pipe and the hole wall. The slurry ratio is dynamically adjusted according to the degree of crack development, and grouting is carried out in zones according to the order of "deep first, shallow later, bottom first, top later", so as to achieve dynamic adjustment of grouting parameters, improve filling effect and project quality, greatly reduce slurrying rate, and at the same time use industrial solid waste to prepare slurry to achieve green and efficient management of goaf. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a construction flow chart of the present invention. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] See also Figure 1 The present invention provides a technical solution: a multi-layer old goaf drilling grouting filling method, comprising the following steps: S1. Drilling construction: Mark the hole location and drill the hole. Select a rotary drill or percussion drill with a 127mm drill bit according to the geological conditions. When the drill bit penetrates the loose soil layer and enters the stable bedrock for ≥6m, promptly insert a 114mm steel pipe to protect the wall. Subsequently, replace the drilling tool with a 91mm diameter and continue drilling downward with an 89mm drill bit. The drill bit is then allowed to penetrate the target multi-layer goaf in sequence and finally drill to the collapse zone below the lowest goaf or at least 2m below the stable coal seam floor, thus completing the grouting hole drilling operation. After the drilling construction is completed, the hole inclination error of the grouting hole must be strictly ≤1° / 100m. S2. Installation of grouting pipe: After the grouting hole is drilled, the grouting hole should be thoroughly cleaned and inspected first. Only after confirming that the hole is clean and free of residual debris can the Ø50mm grouting pipe be lowered. First, a rubber pad is filled between the grouting pipe and the hole wall. Then, a flange is installed on the side of the grouting pipe above the rubber pad to stop the grouting, which provides a double guarantee to prevent grouting. Finally, an annular airbag is set on the side of the grouting pipe on the flange and inflated. After the annular airbag is inflated, its internal working pressure should be maintained in a constant range of 0.02-0.03MPa to achieve dynamic sealing between the hole wall and the grouting pipe. Finally, clean water is injected to conduct a sealing test; S3. Slurry concentration adjustment: The water-to-solid ratio is dynamically adjusted based on the target goaf and the degree of surrounding rock fissure development as revealed by drilling and previous exploration data to meet the permeability and filling requirements of different areas. In areas with developed fissures, a cement fly ash slurry with a water-to-cement fly ash ratio of 1:1.3 and 2% accelerator is used. In dense areas, a cement fly ash slurry with a water-to-cement fly ash ratio of 1:1.1-1.2 is used. S4. Pressure flushing: Before the formal grouting operation, the grouting holes and the target voids in the holes or the pores of the rock formation that may be connected should be fully flushed with pressurized water to remove blockages such as rock powder and debris and improve the injectability of the slurry. When intermittent grouting is required, intermittent water pressure operation should be carried out in time during each pause in grouting to keep the grouting channel unobstructed and prevent the slurry from settling and solidifying, which may cause the grouting pipeline to be blocked during the next grouting. When the water pressure operation is carried out, the flushing pressure is 80% of the grouting pressure and not more than 1Mpa. The single flushing time is 5-10 minutes. When the water leakage from the hole is observed to be greater than 100L / min, the flushing can be stopped. S5. Zoned grouting: Follow the principle of "deep first, shallow later, bottom first, top later, curtain hole first, grouting hole later" and inject grouting at intervals to avoid slurry layer cross-over. The slurry is diluted first and then thickened. First, inject the diluted slurry to expel the air inside, and then adjust the slurry concentration step by step. The grouting pressure is dynamically adjusted according to the void ratio of the fracture zone in the goaf. Under the final pressure condition, the grouting volume is ≤70L / min and the injection is stopped after 15-20 minutes. The final hole pressure is 1-3MPa. S6. Grouting treatment: When grouting occurs at the orifice, reduce the pressure to 0.5-1MPa, flow rate ≤30L / min and grout intermittently. If it is ineffective, reinstall the air bag until the grouting operation is completed; S7. Grouting effect detection: 6 months after construction, drill holes at representative goaf locations or locations where abnormal conditions occurred during construction to conduct full-hole core sampling to directly observe the slurry filling conditions in the goaf, and evaluate the treatment effect in combination with the stone core compression test and in-hole television observation.

[0018] The present invention adopts a drilling process that penetrates multiple layers with one hole, which can shorten the construction period, and replaces the traditional hole pipe casting process with annular airbag sealing technology to achieve sealing between the grouting pipe and the hole wall. The slurry ratio is dynamically adjusted according to the degree of crack development, and grouting is carried out in different areas in the order of "deep first, shallow later, bottom first, top later", so as to achieve dynamic adjustment of grouting parameters, improve filling effect and project quality, greatly reduce slurrying rate, and use industrial solid waste to prepare slurry to achieve green and efficient management of goaf areas.

[0019] Any undisclosed portions of the present invention are prior art, and their specific structures, materials, and operating principles will not be described in detail. Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-layer old goaf drilling grouting filling method, characterized in that: The following steps are involved: S1. Drilling construction: Mark the hole location and drill with a 127mm drill bit. When the drill bit penetrates the loose soil layer and enters the stable bedrock for ≥6m, promptly insert a 114mm steel pipe to protect the wall. Subsequently, replace the drilling tool with a 91mm diameter and continue drilling downward using an 89mm drill bit. The drill bit is allowed to successively penetrate the target multi-layer goaf and finally drill to the collapse zone below the lowest goaf or at least 2m below the stable coal seam floor, thus completing the grouting hole drilling operation. S2. Grouting pipe installation: After the grouting hole is drilled, first clean the hole thoroughly and check it. Then, insert the Ø50mm grouting pipe. First, fill the rubber pad between the grouting pipe and the hole wall. Then, install the flange on the side of the grouting pipe above the rubber pad to stop the grouting. Finally, install an annular airbag on the side of the grouting pipe on the flange and inflate it. Finally, inject clean water to test the sealing performance. S3. Slurry concentration adjustment: Dynamically adjust the water-solid ratio based on the target goaf and surrounding rock fissure development degree obtained from drilling revelations and previous exploration data to adapt to the permeability and filling requirements of different areas; S4. Pressure flushing: Before the formal grouting operation, the grouting holes and the target voids in the holes or the pores in the rock formation that may be connected should be fully flushed with pressurized water. When intermittent grouting is required, intermittent water pressure operation should be carried out in time during each pause in grouting. S5. Zoned grouting: Grouting is performed at intervals to avoid slurry cross-layering. The slurry is diluted first and then thickened. The diluted slurry is injected first, and the slurry concentration is adjusted step by step. The grouting pressure is dynamically adjusted according to the void ratio of the fracture zone in the goaf. Under the final pressure condition, the grouting volume is ≤70L / min and the injection is stopped after 15-20 minutes. The final hole pressure is 1-3MPa. S6. Grouting treatment: When grouting occurs at the orifice, reduce the pressure to 0.5-1MPa, flow rate ≤30L / min and grout intermittently. If it is ineffective, reinstall the air bag until the grouting operation is completed; S7. Grouting effect detection: 6 months after construction, drill holes at representative goaf locations or locations where abnormal conditions occurred during construction to conduct full-hole core sampling to directly observe the slurry filling conditions in the goaf, and evaluate the treatment effect in combination with the stone core compression test and in-hole television observation.

2. The multi-layer old goaf drilling grouting filling method according to claim 1 is characterized in that: In S1, a rotary drill or a percussion drill is selected for drilling according to the geological conditions.

3. The multi-layer old goaf drilling grouting filling method according to claim 1 is characterized in that: In S1, after the drilling construction is completed, the hole inclination error of the grouting hole must be strictly ensured to be ≤1° / 100m.

4. The multi-layer old goaf drilling grouting filling method according to claim 1 is characterized in that: In S2, after the annular airbag is inflated, its internal working pressure should be maintained in a constant range of 0.02-0.03 MPa.

5. The multi-layer old goaf drilling grouting filling method according to claim 1 is characterized in that: In S3, the fracture development zone uses cement fly ash slurry with a water to cement fly ash ratio of 1:1.3, and the cement fly ash slurry contains 2% accelerator, and the dense zone uses cement fly ash slurry with a water to cement fly ash ratio of 1:1.1-1.

2.

6. The multi-layer old goaf drilling and grouting filling method according to claim 1 is characterized in that: In S4, when performing water pressure operation, the flushing pressure is 80% of the grouting pressure and not more than 1Mpa; the single flushing time is 5-10min. When the orifice leakage is observed to be greater than 100L / min, the flushing can be stopped.

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