A grouting plugging method for full-section horizontal tunnel with grouting

Abstract

The present invention discloses a grouting and plugging method for a full-section horizontal tunnel with grouting stoppers. The grouting boundary and the reasonable hole arrangement are controlled by the grouting stoppers, and secondary grouting for shallow hole reinforcement and segmented hydrophobic bottom plate grouting are performed to form a set of economical, efficient and convenient construction methods. The method solves the problems of poor grouting effect and low treatment success rate of traditional post-grouting under geological conditions with high water pressure and more developed fracture zones, reduces grouting leakage, ensures slurry injection efficiency, increases slurry diffusion radius, and improves grouting effect. At the same time, it simplifies the operation process, reduces grouting costs, and shortens grouting period. The present method has good effects in full-section horizontal tunnels with grouting, and can be widely used in post-grouting of horizontal tunnels with complex hydrogeological conditions.

Description

Technical Field

[0001] The invention relates to a method for controlling water gushing from the entire cross section of an exposed horizontal tunnel, and in particular to a method for grouting and plugging a grout stopper in a horizontal tunnel with an entire cross section, belonging to the technical field of mining. Background Art

[0002] Grouting water blocking is to use a grouting pump to inject slurry into the water-bearing rock layer through the grouting hole, so that it fills the cracks in the rock layer and solidifies, blocking the path of groundwater flowing into the tunnel, thereby reducing the amount of water in the tunnel and preventing water seepage. The post-grouting construction process mainly uses shallow hole grouting to block the water inflow point, which can effectively treat the exposed water-bearing cracks and control the overall water volume in the tunnel.

[0003] The stress of the formed tunnel is redistributed due to the change of boundary conditions, forming a loose circle in the surrounding rock and generating a large number of fractured zones. On the one hand, it is easy to get stuck in the drill and it is difficult to make holes during the grouting hole construction. On the other hand, if the injection head is not well controlled, slurry leakage and slurry leakage are likely to occur, affecting the quality of grouting and plugging water. If the water pressure is high and there are many fracture zones during the construction of conventional post-grouting, the grouting effect is very poor and the success rate of treatment is low. If the entire section of the tunnel is watered, the conventional grouting method is likely to cause water source transfer, resulting in the phenomenon of "water-by-water construction".

[0004] On the other hand, in the existing tunnel post-grouting construction, the boundary is mostly controlled by using a hole pipe plus hemp rope and other sealing materials, which has the problems of complicated construction, poor sealing quality, and the inability to recycle the hole pipe. Summary of the invention

[0005] The technical problem to be solved by the present invention is to propose a grouting and plugging method for a full-section horizontal tunnel with a slurry stopper, which solves the problems of slurry leakage and poor grouting effect during grouting in a full-section water-gushing tunnel, effectively releases the water pressure of the gushing water, ensures the slurry injection efficiency, increases the slurry diffusion radius, and improves the grouting effect.

[0006] The technical solution of the present invention is as follows:

[0007] A method for grouting and plugging a full-section horizontal tunnel with a grout stopper, characterized by comprising the following steps:

[0008] The first step is to use stop plugs for boundary control;

[0009] Step 2: Hole layout design:

[0010] 1) Shallow grouting holes: Drill multiple shallow grouting holes within 0.8-1.2m from the water outlet. The axis of the shallow grouting holes is at an angle of 40-70 degrees to the horizontal direction. The depth of the holes is increased from small to large according to the angle. The shallow grouting holes pass through the water-bearing fracture zone. The shallow grouting holes are arranged in a row every 1.5-2m. The number of holes drilled in each row and at each depth is calculated according to formula ①.

[0011] ①

[0012] Where: N—number of grouting holes, pieces;

[0013] B—tunnel width, m;

[0014] h—wall height, m;

[0015] 2) Drain hole: Drill a hole 2.0-3.0m away from the water outlet, with a depth of 6-8m and a diameter of Ф40-Ф45. The axis of the drain hole forms an angle of 40-70 degrees with the horizontal direction, and the drain hole passes through the water-bearing fracture zone; after the hole is formed, install the orifice pipe and connect the high-pressure ball valve; the high-pressure ball valve is in the normally open state, and the water is discharged to reduce the hydrostatic pressure of the grouting hole. The distance between the drain holes is 0.8-1.2m;

[0016] Drain holes are arranged in a row every 1.5-2m, and the number of holes drilled in each row and at each depth is calculated using formula ①;

[0017] The third step is to perform secondary grouting for shallow hole reinforcement on the top wall and segmented drainage grouting on the bottom plate. The steps are as follows:

[0018] 1) Shallow hole reinforcement secondary grouting

[0019] Shallow hole grouting: Drilling and grouting are carried out in sequence, one hole is drilled and one hole is grouted. During grouting, ensure that the drain hole is in a draining state; open and close the drain valve at any time according to the amount and pressure of injected slurry, close the valve when the drain valve is slurry out, open the valve when the tunnel wall leaks slurry, and repeat the cycle until the single hole grouting is completed; perform grouting operations on each shallow grouting hole in turn;

[0020] Secondary grouting: When the shallow hole grouting is completed and there is no water dripping from the tunnel wall, secondary grouting is started from the drainage hole to increase the slurry diffusion radius and grouting is performed until the set grouting final pressure is reached;

[0021] 2) Grouting of segmented drain bottom plate

[0022] Segmented drainage: Divide the bottom plate into sections according to the continuity of water discharge from the bottom plate. The length of each section is 5-20m. Build walls with cement and gravel at both ends of each section. Drain the water from the upper section through gravity through buried pipes in the upstream wall of the grouting section. Pump out the water from the grouting section with a water pump. Then clean the working surface and seal the cracks.

[0023] In the first step, a grouting plug is driven into the borehole. The depth of the grouting plug is based on the working section being completely immersed in the borehole, and double-liquid grouting is performed.

[0024] In the second step, the hole density is adjusted according to the on-site rock conditions and water release volume, and the hole density is increased in areas with many water-bearing fractures, high water release velocity, and large water volume.

[0025] The third step is the segmented hydrophobic base plate grouting: during the grouting process, if there are many vertical cracks that cause leakage, add sawdust or shredded cotton yarn to the cement slurry for spot grouting; or use sawdust and cotton yarn to nail the cracks for spot grouting, and then grout normally when there is no leakage.

[0026] The positive effects of the present invention are:

[0027] First, the present invention adopts grouting plugs for boundary control. Grouting plugs are important instruments in grouting projects to prevent grouting from returning from drilling holes, to use grouting pressure reasonably, to control the grouting range, and to ensure the quality of grouting. The working principle is that under the action of axial compression or other external forces, the sealing member will expand radially and squeeze against the inner wall of the borehole or casing, thereby isolating the slurry in the grouting section and achieving pressure control. Grouting plugs are mostly used in wellbore grouting and are less used in post-grouting in tunnels, and there is a lack of molded construction plan templates. Since grouting plugs are reusable and easy to construct, they can greatly save construction costs and improve construction efficiency.

[0028] Second, the construction method of the present invention mainly adopts shallow hole grouting and deep hole drainage. The shallow hole reinforcement secondary grouting method is used during grouting, which can effectively release the water pressure of the gushing water, ensure the slurry injection efficiency, increase the slurry diffusion radius, and improve the grouting effect.

[0029] Third, the drilling arrangement of the present invention has unique technical measures and technical effects, which are as follows:

[0030] 1. Arrange the grouting holes from shallow to deep and coordinate with the drainage holes to ensure uniform distribution of the slurry and prevent roof collapse and spalling due to excessive local pressure.

[0031] 2. Ensure drilling efficiency by reasonably selecting the drilling opening position, drilling length and drilling angle, ensure the operation of slurry in the cracks, and improve the grouting quality. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with embodiments and technical effects.

[0033] This embodiment is the construction of the main return airway in the middle section of -600m of a certain mine. The cross-sectional specifications of the return airway shaft are 6m wide and 5m high, with a wall height of 3.5m and an arch height of 1.5m. It is supported by anchor spraying and has a support thickness of 100mm. Its horizontal position coincides with the direction of the surface coastline. A large number of water-bearing fracture zones are developed in the return airway. Most of the water-bearing fracture zones are perpendicular to the direction of the tunnel. The overall water inflow can reach 200m³ / h. When the construction was near the head, water came out from the right side of the tunnel head, and the roof of the 17m area at the head was seriously watered. According to on-site water measurement, the water inflow (drenching) was 73m³ / h; this water inflow (drenching) seriously affected the progress and quality of the project construction, and caused great hidden dangers to safe construction. In view of the above situation, double-liquid grouting was carried out to block the water in the full-section water inflow (drenching) section in the return airway, and the head water outlet point was blocked.

[0034] 1. Drilling arrangement

[0035] (1) Shallow hole arrangement for grouting: Drill holes about 1m away from the water outlet. The main hole depths are 2.5m, 3.5m, and 5m. The holes are drilled at an angle of 40-70 degrees to the horizontal direction through the water-bearing fracture zone. The hole depth increases from small to large according to the angle. Drain holes and grouting holes are arranged in a row every 1.5-2m. The number of holes drilled in each row and at each depth is calculated according to formula ①.

[0036] ①

[0037] Where: N—number of grouting holes, pieces;

[0038] B—tunnel width, 6m;

[0039] h—wall height, take 5m.

[0040] The calculated number is N=13.

[0041] (2) Drain hole arrangement: Drill a hole about 2.5m away from the water outlet, with a depth of 7m and a diameter of 42mm. Pass through the water-bearing fracture zone at an angle of 40-70 degrees to the horizontal direction. After the hole is drilled, install the orifice pipe and connect it to a DN25 high-pressure ball valve. The number of drain holes is also calculated using formula ①, and N=13. The high-pressure ball valve is in the normally open state. Draining water reduces the hydrostatic pressure of the grouting hole. The distance between drain holes is about 1m.

[0042] 2. Grouting construction

[0043] (1) Grout stopper controls the grouting boundary

[0044] In view of the geological characteristics of the development of a large number of water-bearing fissures perpendicular to the head-on direction, a Ф42*400mm grouting plug is driven into the borehole. The depth of the grouting plug is based on the complete immersion of the working section of the grouting plug in the borehole. A Φ34x8mm seamless steel pipe is used as the grouting pipe, one two meters long, with threads on both ends. A Ф47*8mm seamless pipe is used to process the pipe clamp, which is connected to the connecting pipe and the grouting plug through internal threads; the injection head is connected to a DN25 high-pressure ball valve for double-liquid grouting.

[0045] (2) Determination of main construction parameters

[0046] Shallow hole grouting: Drilling and grouting are carried out in sequence, one hole is drilled and one hole is grouted. During grouting, ensure that the drain hole is in a draining state. Open and close the drain valve at any time according to the amount of slurry injected and the pressure. Close the valve when the drain valve is slurry flowing out, open the valve when the tunnel wall leaks slurry, and repeat the cycle until the single hole grouting is completed.

[0047] Secondary grouting: Grouting in shallow holes until there is no water dripping from the tunnel wall, start secondary grouting from the drainage hole to increase the slurry diffusion radius, and grouting until the set grouting final pressure is reached. The set grouting final pressure is 2.5 times the hydrostatic pressure, which is 7-12MPa. The low value is used for grouting to seal large cracks in the early stage, and the high value is used for grouting small cracks in the later stage. The water pressure test pressure is 1.2 times the grouting final pressure, which is 8-14MPa.

[0048] The grouting parameters are shown in Table 1:

[0049] Cement Model Water glass concentration Water glass modulus Water, ash, water glass mass ratio Final grouting pressure Water pressure test pressure PO42.5 40-50 degrees Baume 2.3-2.8 1:1:0.8 7-12MPa 8-14MPa

[0050] (3) Construction process

[0051] ①Operation procedures:

[0052] After being stirred by the mixing system, the slurry enters the rock formation through the grouting pump, grouting pipe, and grouting pipe. When the grouting hole is drilled to a predetermined depth, flush the hole with clean water until clean water returns. The grouting operation procedure is as follows: connect the grouting pipeline → water pressure test → grouting → quantitative pressure of clean water → flushing the grouting pipeline → dismantling and cleaning the grouting pump.

[0053] ②Water pressure test

[0054] Before grouting, a water pressure test is carried out to flush the fillings in the rock cracks, improve the bonding strength and impermeability of the slurry stone body and the rock crack surface, and design the injection volume according to the pump pressure.

[0055] ③Adjustment of grouting pressure

[0056] During the grouting process, the grouting pressure changes in three stages: initial, normal and final pressure. After the initial concentration is determined, the pump volume should be controlled in time according to the changes in the grouting pressure, and the slurry concentration and gel time should be adjusted to make the grouting pressure increase smoothly and avoid large fluctuations until the final grouting pressure and final volume are reached and stabilized for 10 minutes.

[0057] ④ Preparation of slurry

[0058] When grouting each borehole, use thick slurry for the initial injection, and gradually reduce the slurry concentration during re-injection. However, each time grouting is generally diluted first and then concentrated. When the slurry is in the stage of fracture precipitation and filling, if the pressure does not rise and the slurry volume does not decrease, the concentration should be gradually increased. On the contrary, if the pressure rises quickly and the volume decreases quickly, at this time, in order to ensure sufficient injection volume, the slurry concentration should be reduced in turn. Each change of slurry concentration lasts for 10 minutes.

[0059] (4) End of grouting

[0060] When the grouting pressure of each grouting hole reaches the designed final pressure value, the injection volume is less than 30-40 L / min and is stable for more than 10 minutes. The grouting end requirements are met. Before the end, a certain amount of clean water needs to be injected to flush the slurry in the pipeline. The injection volume is 80% of the volume of the grouting pipeline and the grouting hole. Then close the orifice high-pressure ball valve, open the slurry valve, and flush the slurry pipeline.

[0061] 3. Grouting treatment effect

[0062] The treatment effect parameters of the embodiment of the present invention are shown in Table 2.

[0063] Table 2 Governance effect parameters

[0064]

[0065] As can be seen from Table 2, the present invention achieves good grouting effect, the water flow in the treatment section is reduced from 73m³ / h to 12m³ / h, and the treatment efficiency reaches 83.56%, meeting the treatment qualification requirements.

Claims

1. A method for grouting and plugging a full-section horizontal tunnel with a grout stopper, characterized in that The following steps are involved: The first step is to use a grout stopper for boundary control: a grout stopper is driven into the borehole, and the depth of the grout stopper is based on the working section being completely immersed in the borehole, and double-liquid grouting is performed; Step 2: Hole layout design: 1) Shallow grouting holes: Drill multiple shallow grouting holes within 0.8-1.2m from the water outlet. The axis of the shallow grouting holes is at an angle of 40-70 degrees to the horizontal direction. The depth of the holes is increased from small to large according to the angle. The shallow grouting holes pass through the water-bearing fracture zone. The shallow grouting holes are arranged in a row every 1.5-2m. The number of holes drilled in each row and at each depth is calculated according to formula ①. ① Where: N—number of grouting holes, pieces; B—tunnel width, m; h—wall height, m; 2) Drain hole: Drill a hole 2.0-3.0m away from the water outlet, with a depth of 6-8m and a diameter of Ф40-Ф45. The axis of the drain hole forms an angle of 40-70 degrees with the horizontal direction, and the drain hole passes through the water-bearing fracture zone; after the hole is formed, install the orifice pipe and connect the high-pressure ball valve; the high-pressure ball valve is in the normally open state, and the water is discharged to reduce the hydrostatic pressure of the grouting hole. The distance between the drain holes is 0.8-1.2m; Drain holes are arranged in a row every 1.5-2m, and the number of holes drilled in each row and at each depth is calculated using formula ①; The third step is to perform secondary grouting for shallow hole reinforcement on the top wall and segmented drainage grouting on the bottom plate. The steps are as follows: 1) Shallow hole reinforcement secondary grouting Shallow hole grouting: Drilling and grouting are carried out in sequence, one hole is drilled and one hole is grouted. During grouting, ensure that the drain hole is in a draining state; open and close the drain valve at any time according to the amount and pressure of injected slurry, close the valve when the drain valve is slurry out, open the valve when the tunnel wall leaks slurry, and repeat the cycle until the single hole grouting is completed; perform grouting operations on each shallow grouting hole in turn; Secondary grouting: When the shallow hole grouting is completed and there is no water dripping from the tunnel wall, secondary grouting is started from the drainage hole to increase the slurry diffusion radius and grouting is performed until the set grouting final pressure is reached; 2) Grouting of segmented drain bottom plate Segmented drainage: Divide the bottom plate into sections according to the continuity of water discharge from the bottom plate. The length of each section is 5-20m. Build walls with cement and gravel at both ends of each section. Drain the water from the upper section through gravity through buried pipes in the upstream wall of the grouting section. Pump out the water from the grouting section with a water pump. Then clean the working surface and seal the cracks.

2. The method for grouting and plugging of a full-section horizontal tunnel with a grout stopper as claimed in claim 1 is characterized in that In the second step, the hole density is adjusted according to the on-site rock conditions and water release volume, and the hole density is increased in areas with many water-bearing fractures, high water release velocity, and large water volume.

3. The method for grouting and plugging of a full-section horizontal tunnel with a grout stopper as claimed in claim 1 is characterized in that The third step is the segmented hydrophobic base plate grouting: during the grouting process, if there are many vertical cracks that cause leakage, add sawdust or shredded cotton yarn to the cement slurry for spot grouting; or use sawdust and cotton yarn to nail the cracks for spot grouting, and then grout normally when there is no leakage.

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