A high-pressure grouting treatment method for deep-buried tunnels in large-water deposits

Abstract

The invention discloses a high-pressure grouting treatment method for a deep-buried tunnel of a large water deposit, comprising the following steps: step one: before the grouting and water blocking construction, a water exploration hole is constructed; step two: for a stratum with a water gushing pressure greater than 1MPa or a water gushing volume greater than 10m3 / h or with serious mud or sandification as discovered by drilling, a solid water splitting grouting method is adopted, and other strata are adopted with a conventional grouting process; step three: when the solid water splitting grouting method is adopted, a transition grouting material with good permeability, large diffusion radius, controllable consolidation time and low strength is first poured into the grouting hole; step four: when the transition grouting pressure reaches 10MPa and no more grout is absorbed, pure cement slurry is started to be poured; step five: when the rock mass is highly broken or the stratum is seriously mud or sandified and other geological conditions are complex, steps three and four can be repeated, and compared with the conventional grouting process, the injection amount of cement slurry can be greatly increased, so that the cement body can overlap the broken surrounding rock within the excavation range, thereby achieving a better water-stopping reinforcement effect.

Description

Technical Field

[0001] The invention relates to the field of grouting technology for mine tunnels, and in particular to a high-pressure grouting treatment method for deep-buried tunnels in large-water mines. Background Art

[0002] With the increasing depletion of shallow resources, mining in my country has extended to deeper areas. The complex mechanical environment of "three highs and one disturbance" in the deep has made mine water inrush a severely affected area for water inrush accidents in my country. All kinds of water may enter the underground through structural fractures, rock fissures, mining disturbance fissures and other water inrush channels, seriously affecting the normal production of the mine, causing direct economic losses and even causing casualties.

[0003] At present, grouting reinforcement measures are often taken to solve and prevent mine water hazards. It has the advantages of small disturbance, portable construction, unrestricted working site, and wide applicability. Anchor-grouting integration or combined support and grouting reinforcement measures are often adopted. The grouting reinforcement process often adopts pure pressure grouting. Commonly used grouting materials mainly include ordinary Portland cement, cement with additives (water glass, salt, triethanolamine, etc.), and cement-water glass slurry.

[0004] However, compared with shallow mining, deep mining has the characteristics of high and low temperature, high ground stress and high external water pressure. The on-site grouting practice of broken rock strata with a burial depth of more than 400m in large water deposits shows that when encountering high-pressure water inrush, especially when the water inrush pressure is greater than 3MPa and the water inrush volume is as high as 100m3 / h or more, pure pressure cement grouting is used. The grouting pressure in the borehole rises rapidly and quickly reaches the grouting end standard. Even if the grouting pressure in the hole is increased to 2 to 3 times the head pressure value of the aquifer at the borehole mouth, it still cannot effectively increase the injection volume of cement slurry. There are problems such as water absorption but not slurry, difficulty in pouring cement slurry, limited grouting reinforcement range, poor effect, and water inrush and collapse after excavation. In the later stage, not only multiple support methods need to be added, but also repeated hole sweeping and multiple grouting are required, resulting in extended construction period, low efficiency and high cost.

[0005] Mines have been using cement slurry or cement water glass slurry for grouting reinforcement work. The grouting materials are relatively single. The main reason why it is difficult to achieve high-pressure top water grouting in deep, high-pressure water-bearing surrounding rocks is that the cracks in the deep rock mass are small. Cement slurry is a granular grouting material that is easy to hydrate and consolidate. Under high pressure conditions, the water in the cement slurry quickly penetrates and dissipates from the rock cracks, and the remaining cement particles fill the rock cracks, pores and orifice tubes near the borehole and form a filter layer with increasing thickness (non-dense structure, permeable to water but not to slurry) as the slurry is injected. It even solidifies rapidly under high temperature and high pressure, resulting in a rapid increase in grouting pressure. The grouting end standard is reached when the diffusion radius of the slurry does not meet the design requirements, and the thickness of the curtain is difficult to guarantee. Therefore, due to the limited diffusion radius of cement slurry, the slurry entity cannot be effectively overlapped, and there are still grouting blank zones in the broken rock layer after grouting reinforcement. There is still high-pressure water with good hydraulic connection between the gaps that are not completely filled, so that the working face still suffers from water inrush and collapse accidents after multiple cycles of grouting reinforcement. For this reason, we propose a high-pressure grouting treatment method for deep buried tunnels in large water deposits to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a high-pressure grouting treatment method for deep-buried tunnels in high-water mineral deposits to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a high-pressure grouting treatment method for deep-buried tunnels in a large-water deposit, comprising the following steps:

[0008] Step 1: Before grouting and plugging water, a water exploration hole is constructed. The water exploration hole is located on the centerline face. The whole hole is cored to find out the integrity, permeability and water pressure of the rock mass in the construction section. The curtain thickness, grouting reinforcement depth and grouting plan are determined according to the degree of rock mass fragmentation, pressure of pressurized water and tunnel excavation depth.

[0009] Step 2: For the formations with proven water pressure greater than 1MPa or water flow greater than 10m3 / h or serious mud and sand formation, the solid water splitting grouting method is used, and the other formations are used by conventional grouting technology;

[0010] Step 3: When adopting the solid-water splitting grouting method, first pour the transition grouting material with good permeability, large diffusion radius, controllable consolidation time and low strength into the grouting hole, solidify the water in the cracks and pores of the rock formation around the borehole and consolidate with the rock mass to form a relative water-proof curtain with a certain strength and thickness, cut off the direct connection between the cement slurry and the high-pressure water gushing through the transition rock mass, reduce the water gushing amount and water gushing pressure of the broken surrounding rock in the borehole, and provide a water-free and low-pressure environment for the later injection of cement slurry;

[0011] Step 4: When the transition grouting pressure reaches 10MPa and there is no more grout absorption, start to grout pure cement slurry. Pure cement slurry is composed of water and cement with a water-cement ratio of 5:1 to 2:1. When the grouting pressure reaches 20MPa and there is no more grout absorption, the single-hole grouting is completed.

[0012] Step 5: When the rock mass is severely broken or the geological conditions are complex, such as serious mud and sand formation, steps 3 and 4 can be repeated. That is, when the cement slurry is no longer added, the transition grouting material and cement slurry are continuously and alternately poured back and forth to further improve the overlap of the cement slurry body in the broken surrounding rock and expand the curtain thickness.

[0013] Preferably, the transition grouting material is a low-strength, high-water-content solution-type flexible chemical slurry, which is required to have a stone body compressive strength of 0.3MPa to 0.8MPa and an adjustable gel time of 20min to 40min. One or more of silica sol, acidic water glass, acrylate or acrylate grouting materials can be selected according to the physical and mechanical properties and uses of the reinforced rock mass.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Compared with conventional grouting technology, it can greatly increase the injection volume of cement slurry, effectively increase the diffusion radius of cement slurry, and increase the curtain thickness after grouting construction, so that the cement body can overlap the broken surrounding rock within the excavation range, achieving a better water-stopping reinforcement effect;

[0016] 2. For high-pressure water gushing grouting construction of deeply buried broken surrounding rocks, after the conventional grouting method is constructed, the curtain thickness is not enough, the surrounding rock consolidation effect is poor, and the local part is still loose and broken. During the excavation process, there is water gushing again, the top slag collapses or local fall. It is necessary to carry out secondary or even multiple repeated hole sweeping grouting or adopt multiple support forms for combined support, which has the problems of high material consumption, long construction period and increased investment. After the construction of the patented solid water splitting grouting process, there is no obvious water gushing in the inspection hole and the face after excavation, and the surrounding rock reinforcement is complete;

[0017] 3. This patent can also be applied to the management of water gushing from clay mineral-developed rock formations, muddy sandy rock formations, dense loose gravel layers, and other water-rich formations with poor irrigation properties and complex geological conditions. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] The first embodiment of the present invention provides a high-pressure grouting treatment method for deep-buried tunnels in a large-water mineral deposit, including: when grouting and water-blocking reinforcement is performed on deeply buried water-rich surrounding rocks, for strata where cement slurry is difficult to inject or the effect is not good, first inject a solution-type transition grouting material with good permeability and a large diffusion radius, wait for the solution-type transition grouting material to fully penetrate into the cracks and pores of the rock strata and form a waterproof curtain with a strength of no more than 0.5MPa with the strata, and then inject cement slurry, and split and destroy the waterproof curtain body by high pressure, so that the cement slurry is transformed from infiltration and squeezing into a splitting, infiltration, and squeezing mode, thereby increasing the injection amount and diffusion radius of the cement slurry. diameter, to achieve the effect of reinforcing the broken surrounding rock. This method mainly uses two different grouting materials to alternately grout. One is used to consolidate water to form a transitional rock mass with low strength, so as to cut off the direct connection between cement slurry and high-pressure water gushing, and reduce the impact of high-pressure water gushing on the broken surrounding rock. The other is high-pressure grouting cement slurry, which forms a criss-cross network skeleton structure in the broken rock mass through splitting, infiltration, extrusion and other methods, forming a higher strength consolidated body, increasing the elastic modulus of the rock mass, and further improving the overall strength and bearing capacity of the broken rock mass, so as to achieve balanced reinforcement of the tunnel surrounding rock stress and meet the requirements of excavation and tunneling.

[0021] Example 2

[0022] The second embodiment of the present invention is based on the above embodiment. Specifically, the Macheng Iron Mine is located in Macheng Town, Luannan County, Hebei Province. The surface of the mining area is covered by Quaternary strata, and faults are developed in the area, which are three main faults F1, F2, and F3. The return air shaft of the Macheng Iron Mine is located in the upper plate of the ore body and needs to cross the F2 fault. The F2 fault runs nearly north-south. The rocks in the fault zone are broken, cracks are developed, and various stresses are concentrated. The return air stone gate includes six horizontal projects of -240m, -480m, -540m, -600m, -840m, and -900m. The tunnel is buried deep, the bedrock water level is shallow, and the deepest mining level is as high as 9Mpa.

[0023] The Macheng mining area is a metamorphic rock stratum with a complex composition. The fault area is affected by alteration, and clay minerals such as kaolin and chlorite are widely developed, which block the grouting channel and prevent the slurry from consolidating with the rock mass, increasing the difficulty of grouting and reducing the water plugging and reinforcement effect. After treatment, water leakage or local caving still occurs again. For example, after the treatment of the -900m broken zone of the 3# return air shaft, the weak rock mass on the working face experienced caving and water leakage again during the excavation process.

[0024] In order to improve the collapse of the broken zone during the treatment process, the construction process of first injecting silica sol material for grouting and water stopping, and then injecting cement slurry for reinforcement was adopted during the treatment of the broken zone at -480m and -540m of the return air shaft:

[0025] Grouting preparation: Before grouting, the grouting hole should be drained. The continuous draining time should not be less than 30 minutes to fully flush the rock powder and gravel in the rock cracks in the hole. When the water volume in the hole is less than 20m 3 / h, water should be injected for 30 minutes before grouting to keep the cracks unobstructed and enhance injectability.

[0026] Grouting method: adopt segmented forward grouting method, the grouting section length is 5 to 15m. It depends on the water flow of a single hole. When the water flow of a single hole is greater than 10m 3 / h, grouting will start immediately after drilling 1 to 2m deep, and the solid water splitting grouting method will be used for construction.

[0027] Grouting slurry: Pure cement slurry is mainly used. When the cement slurry injection volume is large or in the core drilling hole, cement-water glass double liquid slurry is used to control the effective diffusion radius. In the section with small cement slurry injection volume or water inflow volume greater than 10m 3 / h, silica sol slurry is used instead, and cement slurry is poured after it is injected into the fine joints and fissures. The water-cement ratio of cement slurry is 5:1, 3:1, 2:1, until the grouting end standard is reached; the silica sol gel time is controlled at 40 minutes.

[0028] Grouting end standard: During the grouting process, the grouting pressure will gradually increase, and the final grouting pressure is controlled at 15-18Mpa. When the grouting reaches the designed final pressure, the grouting volume is less than 10L / min, and the grouting can be ended after stabilization for 30 minutes. When pouring silica sol, when the grouting pressure reaches 10MPa, the cement slurry is poured immediately until the cement slurry reaches the final pressure of 18MPa, and the grouting volume no longer increases significantly, the grouting is ended.

[0029] After silica sol injection, the hole collapse situation was significantly improved, and the water blocking effect was good. The water inflow of the whole hole was basically less than 1m 3 / h. .

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-pressure grouting treatment method for deep-buried tunnels in a large-water deposit, characterized in that: The following steps are involved: Step 1: Before grouting and plugging water, a water exploration hole is constructed. The water exploration hole is located on the centerline face. The whole hole is cored to find out the integrity, permeability and water pressure of the rock mass in the construction section. The curtain thickness, grouting reinforcement depth and grouting plan are determined according to the degree of rock mass fragmentation, pressure of pressurized water and tunnel excavation depth. Step 2: For the formations with proven water pressure greater than 1MPa or water flow greater than 10m3 / h or serious mud and sand formation, the solid water splitting grouting method is used, and the other formations are used by conventional grouting technology; Step 3: When adopting the solid-water splitting grouting method, first pour the transition grouting material with good permeability, large diffusion radius, controllable consolidation time and low strength into the grouting hole, solidify the water in the cracks and pores of the rock formation around the borehole and consolidate with the rock mass to form a relative water-proof curtain with a certain strength and thickness, cut off the direct connection between the cement slurry and the high-pressure water gushing through the transition rock mass, reduce the water gushing amount and water gushing pressure of the broken surrounding rock in the borehole, and provide a water-free and low-pressure environment for the later injection of cement slurry; Step 4: When the transition grouting pressure reaches 10MPa and there is no more grout absorption, start to grout pure cement slurry. Pure cement slurry is composed of water and cement with a water-cement ratio of 5:1 to 2:

1. When the grouting pressure reaches 20MPa and there is no more grout absorption, the single-hole grouting is completed. Step 5: When the rock mass is severely broken or the geological conditions are complex, such as serious mud and sand formation, steps 3 and 4 can be repeated. That is, when the cement slurry is no longer added, the transition grouting material and cement slurry are continuously and alternately poured back and forth to further improve the overlap of the cement slurry body in the broken surrounding rock and expand the curtain thickness.

2. The high-pressure grouting treatment method for deep-buried tunnels in a large-water deposit according to claim 1 is characterized by: The transition grouting material is a low-strength, high-water-content solution-type flexible chemical slurry. The compressive strength of the stone body is required to be 0.3MPa~0.8MPa, and the gel time is adjustable from 20min to 40min. One or more of silica sol, acid water glass, acrylate or acrylate grouting materials can be selected according to the physical and mechanical properties and purpose of the reinforced rock mass.