Grouting construction method for sudden gushing of medium-sand dolomite confined water

Abstract

The application provides a grouting construction method for medium-sand dolomite gushing confined water, which comprises the following steps: firstly, a drilling machine is used to drill a hole through a sectioned orifice pipe, when the single-hole water inflow is greater than or equal to 40 m 3 / h, a short pipe and a long pipe are connected with a water plugging plate core pipe, and the short pipe is connected with a grouting pipe; secondly, a double-liquid double-injection process is used to inject a double-liquid slurry into the gap between the pipe bundle and the hole through the short pipe; finally, after 6-8s of the double-liquid slurry, a single-liquid single-injection process is used to inject a single-liquid slurry through the long pipe, the injection pressure of the single-liquid slurry is continuously increased, the single-liquid slurry is infiltrated into the stratum by using the long pipe wall grouting divergent hole under the continuous action of the pressure, and an effective water interception curtain and an advanced pre-support system are formed. The method solves a series of problems, such as pressure attenuation, slurry backflow, limited range, long time consumption and limited pressure, which exist in the traditional construction. The method belongs to the field of tunnel engineering construction.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of medium sandification dolomite gushing construction method of confined water, especially suitable for single-hole water yield ≥40m 3 / h medium sandification dolomite stratum, also applicable to other single-hole water yield ≥40m 3 / h medium thick stratum, belongs to the field of tunnel engineering construction. BACKGROUND

[0002] Medium sandification dolomite fissure water channel has the characteristics of thin and dense, when groundwater is located above the hole, stress redistribution caused by tunnel (hole) excavation will cause groundwater flow change, and water level will accumulate in weak areas to cause gushing water, even gushing water and sand. Due to the different sandification degree of dolomite and groundwater level, the main performance of medium dolomite construction risk is gushing water. The traditional grouting water plugging process is full-hole forward type (coreless pipe or Φ20 PVC core pipe) grouting, and the grouting pressure directly acts on the water plugging plate, which may cause a series of problems such as grouting pressure attenuation in grouting curtain, slurry backflow, limited range, long time consumption, limited pressure, etc. SUMMARY

[0003] The present application provides a kind of medium sandification dolomite gushing construction method of confined water, to solve the series of problems such as grouting pressure attenuation in grouting curtain, slurry backflow, limited range, long time consumption, limited pressure, etc. in traditional construction.

[0004] To achieve the above-mentioned purpose, a kind of medium sandification dolomite gushing construction method of confined water is adopted, which first uses drilling rig to drill into hole through orifice pipe, when single-hole water yield ≥40m 3 / h, short pipe and long pipe are segmented, long pipe is connected with water plugging plate core pipe, and short pipe is connected with water plugging plate and grouting pipe; secondly, double-liquid double-injection process is used to inject double-liquid slurry into the gap between pipe bundle and hole through short pipe; finally, 6-8s after double-liquid slurry, single-liquid single-injection process is used to inject single-liquid slurry through long pipe, and the injection pressure is continuously increased, and single-liquid slurry is injected, and single-liquid slurry is injected into stratum under the action of long pipe wall grouting divergent hole, to form effective water interception curtain and advanced pre-supporting system.

[0005] The specific construction steps of the method are as follows:

[0006] 1) First, construction preparation is carried out, and then grouting wall is constructed, before grouting wall construction, drilling rig is used to drill hole in medium confined water-rich stratum working face to install water guide pipe to concentrate gushing water;

[0007] 2) Orifice pipe installation, using drill bit to drill hole on the stop wall, drilling depth 130cm-160cm, filling anchor agent in the hole, then installing orifice pipe by artificial cooperation with drilling machine;

[0008] 3) Stop wall reinforcement

[0009] 3.1 Transverse support, outside the range of 0.6m-0.8m from the stop wall, transverse support is added at the bottom of the initial support, a total of 3 sets of transverse support are added to increase the lateral constraint of the initial support under the action of grouting pressure at the position of the stop wall;

[0010] 3.2 Initial support backfill grouting, within the range of 5m-10m from the stop wall, double liquid grout or single liquid grout is used for backfill grouting between the initial support of the arch and the surrounding rock;

[0011] 3.3 Stop wall reinforcement, for the stop wall periphery, construction joint and the front 5-10m, first use double liquid double injection technology to top water and inject double liquid grout to seal the stop wall periphery and construction joint;

[0012] 4) Water closure pressure measurement, sequentially close the orifice pipe with stop valve from top to bottom, then perform pressure measurement: the bottom orifice pipe is connected with the stop valve; the stop valve is connected with the water stop plate with pressure measurement device; open the stop valve; measure water pressure.

[0013] 5) Drilling, connect drill bit with drill rod, sequentially connect pipes to form hole while drilling, drilling length 3-6m or 5-10m, depending on hole collapse and gushing stratum conditions.

[0014] 6) Pipe lowering

[0015] 6.1 Grouting pipe construction, short pipe is Φ20 PVC pipe, length 3-5m, short pipe penetrates through water stop plate and is connected with grouting pipe; long pipe is Φ42 small guide pipe, length is drilling length, long pipe front end is processed into a shuttle head, grouting curtain section long pipe wall is uniformly provided with grouting divergent holes, grouting divergent holes are sealed by applying strong adhesive inside and outside the thin iron sheet with larger hole diameter, long pipe is connected by lining pipe welding, short pipe is connected by pipe clamp + adhesive tape;

[0016] 6.2 Grouting zinc pipe construction, grouting zinc pipe is Φ25 zinc pipe with length 100cm, core pipe body is provided with 2 layers of adhesive tape, one end of the grouting zinc pipe is connected with the inside grouting pipe of the water stop plate by welding, the other end of the grouting zinc pipe and the pipe body extend into the long pipe, the water stop plate with grouting zinc pipe is connected with the orifice pipe;

[0017] 7) Top water grouting

[0018] 7.1 Using double liquid double injection technology to inject double liquid grout through short pipe to seal the gap between pipe bundle and hole, at the same time, grout flows back in the interval pump and seeps into the gap between the filling zinc pipe and the rear end and middle part of the long pipe from the opening position of the water stop plate, forming long pipe grouting plug at the rear end of the zinc pipe.

[0019] 7.2 grouting curtain, hysteresis double slurry 6-8 s, using single liquid single injection process through long tube injection single slurry, slurry in interval pump slurry from zinc pipe out of slurry port position back flow into filling zinc pipe and long tube gap between the front end, further increase the length of long tube stop grouting plug, continuously increase the grouting pressure in the stratum to continuously inject single slurry, so as to realize the purpose of curtain water plugging;

[0020] 8) single hole grouting pressure reaches the design pressure after 10 min, slurry flow is less than 20 L / min, water yield is less than 2-3 L / m / min, and grouting is finished.

[0021] In the foregoing method, the length of the long tube = the length of the short tube + the length of the completed grouting curtain section + the length of the grouting curtain to be injected.

[0022] In the foregoing method, the short tube grouting pressure is 2-4 MPa, and the long tube grouting pressure is 12-18 MPa.

[0023] The foregoing stop grouting and grouting structure includes a water plugging plate, a long tube, a short tube and a grouting zinc pipe, the long tube and the grouting zinc pipe both extend into the orifice pipe, two adhesive tapes are wound around the length direction of the pipe body of the grouting zinc pipe, one end of the grouting zinc pipe is connected and welded with the grouting pipe on the inner side of the water plugging plate, the other end and the pipe body extend into the long tube, the flange of the water plugging plate is connected and fixed to the end of the orifice pipe, one end of the short tube extends into the orifice pipe through the pipe hole of the water plugging plate, and the other end of the short tube is also connected with a grouting pipe.

[0024] In the foregoing stop grouting and grouting structure, the short tube is a Φ20 PVC tube with a length of 3-5 m, the long tube is a Φ42 small guide pipe with a length = the length of the short tube + the length of the completed grouting curtain section + the length of the grouting curtain to be injected, and the grouting zinc pipe is a Φ25 zinc pipe with a length of 100 mm.

[0025] In the foregoing stop grouting and grouting structure, the orifice pipe has a diameter of Φ108 mm x 6 mm and a length of 150-180 cm, and is exposed by 20-30 cm.

[0026] In the foregoing stop grouting and grouting structure, the front end of the long tube is processed into a shuttle head, the pipe wall of the long tube of the grouting curtain section is uniformly provided with grouting divergent holes, and the grouting divergent holes are sealed by applying strong adhesive agent inside and outside the thin iron sheet with a larger hole diameter.

[0027] Compared with existing technologies, this invention employs a dual-liquid dual-injection process, injecting dual-liquid grout into the duct via a short pipe to seal the gap between the pipe bundle and the duct, thus solving the problems of grout backflow and pressure attenuation during later long-pipe grouting. Utilizing the grouting divergence holes in the long pipe wall, under continuous pressure, the single-liquid grout permeates into the formation, reducing physical parameters such as porosity and permeability coefficient in confined, water-rich, medium-grade strata, while improving mechanical indicators such as the internal friction angle φ and cohesion c at the locations of collapsed boreholes and gushing flows. This increases the impermeability of confined, water-rich, medium-grade strata and enhances the self-stabilizing ability at localized collapsed boreholes and gushing flows, forming an effective water-cutting curtain and advanced pre-support system. In addition, this invention has the following advantages:

[0028] 1) It can prevent grout backflow and increase grouting pressure.

[0029] First, a Φ90 drill bit is used to drill a segmented hole in the Φ108 borehole pipe. Next, a Φ42 small guide pipe (hereinafter referred to as the long pipe) and a Φ20 PVC pipe (hereinafter referred to as the short pipe) are installed in the borehole. The length of the Φ20 PVC pipe is determined according to the water output from the borehole. Finally, a dual-liquid dual-injection process is used to inject dual-liquid grout through the Φ20 PVC pipe (geling time controlled between 5 and 30 seconds) to fill the gap between the short pipe and the borehole, and the gap between the long pipe and the core pipe, avoiding grout backflow and pressure loss due to deformation of the plugging plate when injecting single-liquid grout through the Φ42 small guide pipe. The dual-liquid grout is initiated 6-8 seconds later, and a single-liquid single-injection process is used to inject single-liquid grout through the Φ42 small guide pipe. The single-liquid grout backflows at the front end of the zinc pipe, blocking the gap between the Φ42 small guide pipe and the zinc pipe, forming a unified force, effectively improving the subsequent grouting pressure.

[0030] 2) It can increase the length of grouting and water plugging, and speed up the construction progress.

[0031] First, the material of the grouting core tube was changed from a non-crystalline material to a metallic material, which increased the grouting pressure acting on the tube wall. Second, the long tubes were connected by inner tubes and fully welded to the outer tubes, which solved the problem of grout falling off the long tubes. Finally, the front end of the long tubes was made into a shuttle head, which reduced the installation difficulty in special strata (gushing, collapsed holes), increased the grouting length in general and special adverse strata, and solved the problem of multiple grouting and water plugging stages in special locations (such as collapsed holes, gushing, etc.). The stage length and pressure increased by 1.5 to 2.0 times compared with the traditional process, which accelerated the construction progress. Attached Figure Description

[0032] Figure 1 This is a flowchart of the present invention;

[0033] Figure 2 This is a schematic diagram of the grouting and grouting structure of the present invention. Detailed Implementation

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the following will further describe the present application in detail with reference to the drawings, in which the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0035] Embodiment

[0036] With reference to Figure 1 and Figure 2 , the embodiment provides a grouting construction method for sudden gushing water in medium-sand dolomite under pressure, and the operation points are as follows:

[0037] 1) Construction preparation

[0038] Technical preparation: design and explain the grouting and water plugging according to the actual geology.

[0039] Personnel, material and equipment preparation: organize personnel and equipment into the site and report the test.

[0040] 2) Construction of grouting wall

[0041] Before the construction of the grouting wall, a drill is used to drill a hole in the working face of the medium-pressure water-rich stratum to install a water guide pipe to concentrate and guide the sudden gushing water out. The installation position, number and pipe diameter are determined according to the actual situation on site, the water guide pipe is guided out of the grouting wall by 0.3m-0.5m; the anchoring, reinforcing and model installation are the same as the conventional construction; the concrete is poured in two times; and the grouting wall can be removed after the last group of concrete is poured for one day.

[0042] 3) Installation of orifice pipe

[0043] Technical parameters: diameter Φ108mm x 6mm, length 150cm-180cm, exposed 20-30cm,

[0044] Processing: the exposed end of the orifice pipe 5 is connected with a flange plate, two steel bars are welded on the pipe body of the orifice pipe 5 and are wrapped with hemp, the first one is 50-60cm away from the flange plate, and the second one is 50-60cm away from the first one.

[0045] Installation: a Φ130 drill bit is used to drill a hole on the grouting wall, the drilling depth is 130cm-160cm, and the orifice pipe is installed in the hole by manual cooperation with the drill after the hole is filled with anchoring agent.

[0046] 4) Reinforcement of grouting wall

[0047] Transverse support: in order to increase the transverse constraint of the support near the grouting wall, transverse supports are additionally arranged at the bottom of the initial support outside the range of 0.6m-0.8m away from the grouting wall, three sets of transverse supports are arranged, the transverse constraint of the initial support at the position of the grouting wall under the action of the grouting pressure is increased, and the transverse convergence of the initial support at the position of the grouting wall is avoided.

[0048] Initial support backfill grouting: in order to increase the anti-permeability and anti-pressure capacity of the initial support outside the grouting wall, the range of 5-10 m from the grouting wall, the initial support of the arch part and the surrounding rock are backfilled and grouted by double liquid slurry or single liquid slurry, the backfill grouting pressure is 0.5-0.8 MPa, the mixing ratio (volume ratio) of double liquid slurry is C / S=1:1, and the mixing ratio (weight ratio) of single liquid slurry is W / C=1:1.

[0049] Grouting wall reinforcement. In order to increase the anti-permeability and anti-pressure capacity of the grouting wall, the periphery of the grouting wall, the construction joint and the front end 5-10 m (including the grouting wall) are first sealed by double liquid grouting with double injection process, the grouting pressure is 2-4 MPa; then the single liquid grouting with single injection process is used to reinforce the water-rich stratum 5-10 m (including the grouting wall) inside the grouting wall, the grouting pressure is 6-8 MPa, the mixing ratio (volume ratio) of double liquid slurry is C / S=1:1, and the mixing ratio (weight ratio) of single liquid slurry is W / C=1:1.

[0050] 5) Water shutoff pressure measurement

[0051] Water shutoff sequence: the pipe 5 with a water stop valve orifice is closed from top to bottom in turn.

[0052] Pressure measurement steps: first step, the bottom orifice pipe 5 is connected with the water stop valve; second step, the water stop valve is connected with the water stop plate with pressure measurement device; third step, the water stop valve is opened; fourth step, water pressure is measured.

[0053] 6) Drilling

[0054] Technical parameters:

[0055] Drill bit diameter Φ90, drill rod diameter Φ76, drill bit and drill rod are connected, and pipes are connected in turn with drilling.

[0056] Segment distance:

[0057] Non-collapsing hole and gushing stratum: depending on the gushing water amount, the drilling length is 5-10 m.

[0058] Collapsing hole and gushing stratum: depending on the collapsing hole and gushing situation, the drilling length is 3-6 m.

[0059] Supplementary hole depth: determined according to the actual collapsing hole or gushing of the previous drilling.

[0060] 7) Pipe lowering

[0061] 1. Grouting pipe processing and connection

[0062] Processing materials: long pipe 2 is processed by Φ42 small guide pipe, and short pipe 3 is processed by Φ20 PVC pipe.

[0063] Processing length: the processing length of short pipe 3 is the length of grouting plug, the length is 3-5m; the processing length of long pipe 2 is the length of drilling hole, the length of long pipe 2 = the length of short pipe 3 + the length of grouting curtain completed section + the length of grouting curtain to be completed.

[0064] Technical requirements: the front end of long pipe 2 is processed into a shuttle head; the grouting curtain section long pipe 2 is uniformly provided with grouting divergent holes, the hole spacing is 80-100cm in the form of plum blossom, the grouting divergent hole diameter is Φ6mm; the grouting divergent hole is sealed by using thin iron sheet inside and outside coated with strong adhesive which is larger than the hole diameter.

[0065] Connection: long pipe 2 is connected by inner lining pipe, the inner lining pipe diameter is Φ25mm, the length L = 20cm; short pipe 3 is connected by pipe clamp + adhesive tape.

[0066] 2、Grouting zinc pipe construction

[0067] Processing: grouting zinc pipe 4 is processed by using Φ25 zinc pipe, the core pipe length is 100cm, the core pipe body is provided with 2 adhesive tapes, the adhesive tape spacing is 30cm.

[0068] Connection: grouting zinc pipe 4 and the inner side grouting pipe 7 of water plugging plate 1 are connected by welding and then polished, and then connected with long pipe 2 opening.

[0069] Installation: water plugging plate 1 with grouting zinc pipe 4 is flange connected with hole pipe 5, and installed manually.

[0070] 8) Top water grouting

[0071] 1、Grouting principle: divergent-constrained type grouting.

[0072] 2、Grouting sequence: from outside to inside, hole skipping operation, hole filling reinforcement.

[0073] 3、Grouting range: 30m in length, 5m outside the excavation contour line.

[0074] 4、Grouting method: forward type sectional grouting

[0075] 5、Grouting process: double liquid double injection, double liquid single injection, single liquid single injection

[0076] 6、Grouting parameters

[0077] Grouting pressure:

[0078] Top water grouting, grouting of the periphery of grouting wall and construction joint sealing: grouting pressure 2-4Mpa;

[0079] 5-10m inside the grouting wall: grouting pressure 6-8Mpa;

[0080] Grouting curtain: grouting pressure is 12-18Mpa.

[0081] Grouting liquid selection:

[0082] Stops the slurry wall around the plugging slurry: mainly double liquid slurry, single liquid slurry.

[0083] Water slurry: double liquid slurry

[0084] Curtain slurry: mainly single liquid slurry, double liquid slurry (double liquid slurry is mainly used for gushing, hole collapse position).

[0085] Slurry ratio:

[0086] Single liquid slurry (weight ratio): W: C = (0.8-1) / 1, initial setting time 4-6h;

[0087] Double liquid slurry (volume ratio): C / S = 1:1, initial setting time 5-50S; C / S = 1:0.002-0.005, initial setting time 45-90min.

[0088] 7, grouting

[0089] Water injection grouting: double liquid double injection process is adopted to inject double liquid slurry into the gap between the pipe bundle and the hole through the short pipe 3, and at the same time the slurry flows back in the interval pump slurry from the opening position of the water plugging plate 1 to seep into the gap between the filling grouting zinc pipe 4 and the long pipe 2, forming a long pipe 2 grouting plug at the rear end and middle position of the grouting zinc pipe 4, solving the problems of slurry backflow and pressure decay of long pipe 2 grouting in later period, and the grouting pressure is 2-4MPa.

[0090] Grouting curtain: lag double liquid slurry 6-8s, single liquid single injection process is adopted to inject single liquid slurry through long pipe 2, and the slurry flows back from the grouting outlet position of grouting zinc pipe 4 to seep into the gap between the front end of filling grouting zinc pipe 4 and long pipe 2, further increasing the length of the front end of grouting zinc pipe 4 and long pipe 2 grouting plug, which can also solve the problem of slurry pressure decay of long pipe 2 grouting in later period. And increase the grouting pressure to continuously inject single liquid slurry in the formation, so as to achieve the purpose of curtain water plugging. The grouting pressure is 12-18MPa.

[0091] 8, grouting end standard

[0092] After the single-hole grouting pressure reaches the design pressure, the constant pressure is 10min, the slurry flow is less than 20L / min, and the water output is less than 2-3L / m / min.

[0093] 9) Effect verification

[0094] The effect is verified by inspection hole observation method and water output detection method.

[0095] Basic principle: first, use the drilling machine to drill into the hole through the hole pipe 5, when the single-hole water inflow ≥40m 3The short pipe 3 and the long pipe 2 are connected with the grouting zinc pipe 4, the water plugging plate 1 is penetrated in the short pipe 3 and connected with the grouting pipe 7; secondly, the double-liquid double-injection process is adopted to inject the double-liquid slurry into the gap between the pipe bundle and the hole through the short pipe 3, so as to solve the problems of slurry backflow and pressure attenuation of the long pipe 2, the injection amount of the double-liquid slurry is controlled according to the pipe volume of the short pipe 3 and the pumping times; finally, the single-liquid single-injection process is adopted to inject the single-liquid slurry through the long pipe 2 after 6-8s of the double-liquid slurry, and the injection pressure is continuously increased, so as to realize the curtain purpose; the theoretical basis is that the single-liquid slurry is infiltrated into the stratum under the continuous pressure of the long pipe 2, the physical parameters such as the porosity and the permeability coefficient of the medium stratum with pressure water are reduced, the mechanical indexes such as the internal friction angle φ and the cohesion c of the hole collapse and gushing position are improved, the anti-permeability of the medium stratum with pressure water is increased, the self-stability of the local hole collapse and gushing position is improved, and the effective water interception curtain and the advanced pre-supporting system are formed.

[0096] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for grouting construction of medium-sized sandy dolomite with sudden inrush of confined water, the method firstly involves drilling in sections using a drilling rig through a borehole pipe, characterized by: When bedrock fissure water flows through fine, dense, and easily collapsible pores, and gusts forth with a single pore flow rate ≥40m³, 3 At a rate of / h, short and long pipes are installed in sections. The long pipe is connected to the core pipe of the water-blocking plate, and the water-blocking plate is inserted into the short pipe and connected to the grouting pipe. Next, a double-liquid double-injection process is used to inject double-liquid grout into the duct through the short pipe to seal the gap between the pipe bundle and the duct. Finally, after a delay of 6-8 seconds for the double-liquid grout, a single-liquid single-injection process is used to inject single-liquid grout through the long pipe, and the grouting pressure is continuously increased. The single-liquid grout is then injected into the formation through the grouting divergence holes in the long pipe wall under continuous pressure, forming an effective water-cutting curtain and an advanced pre-support system.

2. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 1, characterized in that, The specific construction steps of this method are as follows: 1) First, prepare for construction, and then construct the grout stop wall. Before constructing the grout stop wall, use a drilling rig to drill holes at the working face of the medium-pressure water-rich stratum and install water pipes to concentrate and draw out the sudden gushing water. 2) For the installation of the orifice pipe, a hole is drilled in the grout stop wall with a drilling depth of 130cm to 160cm. After the hole is filled with anchoring agent, the orifice pipe is installed manually in conjunction with the drilling machine. 3) Reinforcement of the grout-stopping wall: 3.1 Lateral support: At a distance of 0.6m to 0.8m from the grout stop wall, lateral support is added to the bottom of the initial support. A total of 3 lateral supports are set to increase the lateral constraint of the initial support at the grout stop wall location under the action of grouting pressure. 3.2 Initial support backfill grouting: within a range of 5m to 10m from the grout stop wall, the initial support of the arch and the surrounding rock shall be backfilled with double-liquid grout or single-liquid grout. 3.3 Reinforcement of the grout-stopping wall: For the perimeter of the grout-stopping wall, construction joints, and the front 5-10m, first use the double-liquid double-injection process to inject double-liquid grout into the top water to seal the perimeter of the grout-stopping wall and construction joints; 4) Water shut-off and pressure test: Close the orifice pipe with the stop valve from top to bottom, and then test the pressure: connect the bottom orifice pipe to the stop valve; connect the stop valve to the water-blocking plate with the pressure testing device; open the stop valve; test the water pressure. 5) Drilling: The drill bit is connected to the drill rod, and the drill pipe is connected to form a hole as drilling progresses. The drilling length is 3-6m or 5-10m, depending on the situation of hole collapse or gushing strata. 6) Lowering the pipe: 6.1 Grouting pipe construction: The short pipe is a Φ20 PVC pipe with a length of 3-5m. The short pipe passes through the water-blocking plate and is connected to the grouting pipe. The long pipe is a Φ42 small guide pipe with a length equal to the drilling length. The front end of the long pipe is processed into a shuttle head. Grouting divergence holes are evenly opened on the wall of the long pipe in the grouting curtain section. The grouting divergence holes are sealed by applying strong adhesive to the inside and outside of a thin sheet of iron larger than the hole diameter. The long pipe is connected by an inner lining pipe, and the short pipe is connected by a Φ25 pipe clamp + tape. 6.2 Grouting zinc pipe construction: The grouting zinc pipe is a Φ25 zinc pipe with a length of 100cm. Two layers of tape are wrapped around the core pipe body along its length. One end of the grouting zinc pipe is connected to the grouting pipe inside the water-blocking plate and welded and fixed. The other end of the grouting zinc pipe and the pipe body extend into the long pipe. The water-blocking plate with the grouting zinc pipe is connected to the orifice pipe. 7) Top water grouting: 7.1 The double-liquid double-injection process is adopted. The double-liquid slurry is injected into the channel through the short pipe to seal the gap between the tube bundle and the channel. At the same time, the slurry is backflowed in the interval pump and seeps into the gap between the zinc pipe and the long pipe from the opening of the water-blocking plate, forming a long pipe slurry stop plug at the rear end of the zinc pipe. 7.2 Grouting curtain, with a lag of 6-8 seconds between the two-component grout, adopts a single-component single-injection process to inject single-component grout through a long pipe. The grout flows back from the zinc pipe outlet in the interval pump grouting and seeps into the gap between the zinc pipe and the long pipe, forming a long pipe stop plug at the front end of the zinc pipe. The grouting pressure is increased to continuously inject single-component grout into the formation, thereby achieving the purpose of curtain water blocking. 8) After the grouting pressure in a single hole reaches the design pressure, maintain the pressure for 10 minutes, the grout flow rate is less than 20 L / min, and the outflow rate is less than 2-3 L / m / min before grouting is completed.

3. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 2, characterized in that: Long pipe length = Short pipe length + Completed grouting curtain section length + Curtain length to be grouted.

4. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 2, characterized in that: The grouting pressure for short pipes is 2-4 MPa, and the grouting pressure for long pipes is 12-18 MPa.

5. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 2, characterized in that: The grouting and sealing structure used in this method includes a water-blocking plate (1), a long pipe (2), a short pipe (3), and a grouting zinc pipe (4). The long pipe (2) and the short pipe (3) are installed inside the orifice pipe (5). The body of the grouting zinc pipe (4) is wrapped with two layers of tape (6) along its length. One end of the grouting zinc pipe (4) is connected to the grouting pipe (7) inside the water-blocking plate (1) and welded and fixed. The other end and the pipe body extend into the long pipe (2). The flange of the water-blocking plate (1) is fixed to the end of the orifice pipe (5). One end of the short pipe (3) passes through the pipe hole opened on the water-blocking plate (1) and extends into the orifice pipe (5). The other end of the short pipe (3) is also connected to the grouting pipe (7) separately.

6. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 5, characterized in that: The short pipe (3) is a Φ20 PVC pipe with a length of 3 to 5 m; the long pipe (2) is a Φ42 small guide pipe with a length equal to the length of the short pipe plus the length of the completed section of the grouting curtain plus the length of the curtain to be grouted; the grouting zinc pipe (4) is a Φ25 zinc pipe with a length of 100 cm.

7. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 5, characterized in that: The orifice tube (5) has a diameter of Φ108mm×6mm, a length of 150cm~180cm, and an exposed length of 20~30cm.

8. The grouting construction method for sudden inrush of confined water in moderately sandy dolomite according to claim 5, characterized in that: The front end of the long pipe (2) is processed into a shuttle head. The pipe wall of the long pipe (2) in the grouting curtain section is uniformly provided with grouting divergence holes. The grouting divergence holes are sealed by applying strong adhesive to the inside and outside of a thin sheet of iron larger than the hole diameter.

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