A step-by-step and segmented tunnel curtain grouting construction pipe group, device and construction method

Abstract

This invention discloses a step-by-step, segmented tunnel curtain grouting construction pipe assembly, device, and construction method, including multiple construction kits. Each kit includes two grouting pipes and one vacuum pipe for insertion into grouting holes at different depths. Each grouting pipe is composed of multiple first grouting pipe segments connected sequentially. The vacuum pipe is composed of multiple interconnected vacuum pipe segments and multiple isolation pipe segments connected at intervals. Each isolation pipe segment has a double-layer sleeve structure, including a second grouting pipe segment with inner and outer sleeves interlocked and an isolation sleeve. The two ends of the isolation sleeve are sealed to the outer walls of the two ends of the second grouting pipe segment, forming a closed, expandable cavities. Using this device and method ensures that cement grout is fully injected into the surrounding rock strata, increases the injection volume of grout, and forms a uniform network of grout veins within the surrounding rock, resulting in good reinforcement. It also effectively controls the grout diffusion range and avoids waste caused by disordered material diffusion.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel grouting reinforcement, and in particular relates to a step-by-step and segmented tunnel curtain grouting construction pipe group, a device and a construction method. Background Art

[0002] During the tunnel construction process, tunnel projects encounter more and more unfavorable geology, and tunnel curtain grouting construction is one of the most effective means to improve the stratum and is increasingly widely used. However, in many original fine-grained soil strata, such as silt sand, silt sand with clay, silt sand with gravel, etc., they are easy to permeate and have poor self-stabilization ability. At the same time, due to the compact and dense fine particles, conventional cement slurry (suspension) is extremely difficult to inject. Even if expensive chemical slurry (solution) is used, its diffusion radius is difficult to exceed 1m, and the strength of the slurry vein stone body is very low, usually less than 0.5MPa (the strength of cement slurry stone body is usually greater than 10MPa), and the effect of stratum grouting reinforcement is unsatisfactory.

[0003] In the actual tunnel curtain grouting construction, methods such as increased drilling, high-pressure grouting, and repeated grouting are often forced to be adopted. However, there are still problems such as small slurry injection volume, slurry vein stone clumping, and uneven reinforcement. It is also easy to cause severe squeezing and disturbance of the surrounding strata, resulting in large deformation and endangering the safety of buildings.

[0004] Therefore, a feasible tunnel curtain grouting method is needed to solve the problem of difficulty in injecting slurry into the original fine-grained soil layer, so as to form a slurry vein stone body with uniform distribution and sufficient strength, and minimize the severe disturbance to the surrounding strata. Summary of the invention

[0005] The purpose of the present invention is to provide a step-by-step and segmented tunnel curtain grouting construction pipe group, device and construction method, which ensures that cement slurry is fully injected into the surrounding rock formation, increases the injection amount of slurry, and forms a uniform network of slurry veins in the surrounding rock, has a good reinforcement effect, and can effectively control the diffusion range of slurry to avoid waste caused by disorderly diffusion of materials.

[0006] The present invention adopts the following technical scheme: a step-by-step and segmented tunnel curtain grouting construction pipe group, characterized in that it includes multiple sets of construction kits, each of which includes two grouting pipes and a vacuum pipe for inserting into grouting holes of different depths; wherein:

[0007] Each grouting pipe is composed of a plurality of first grouting pipe sections connected in sequence;

[0008] The vacuum tube is composed of a plurality of interconnected vacuum tube sections and a plurality of isolation tube sections connected at intervals, and the vacuum tube section is connected at the front end, and the middle of each vacuum tube section is connected to the grouting hole; each isolation tube section is a double-layer casing structure, including a second grouting tube section and an isolation bag sleeve arranged together inside and outside, and the two ends of the isolation bag sleeve are tightly fitted with the outer walls of the two ends of the second grouting tube section to form an expansion bag cavity with closed ends; the front end of the first grouting tube section and the vacuum tube section at the front end is closed;

[0009] The middle section of each first grouting pipe section and the second grouting pipe section is a small diameter section, and a rubber reset sleeve is sleeved on the small diameter section; on the outer wall of the small diameter section, a plurality of overflow holes are arranged at intervals in a circumferential direction, and each overflow hole is in the shape of a truncated cone with a large outer end and a small inner end from the outside to the inside, and each overflow hole is provided with a one-way plug consistent with its shape; under the grouting pressure, each one-way plug can move outward in the overflow hole, and the outer end pushes up the rubber reset sleeve to form an overflow channel connected at both ends, which is connected to the grouting hole; and when there is no grouting pressure, the rubber reset sleeve shrinks to close the overflow channel;

[0010] In the isolation pipe section, the overflow channel is connected with the expansion bladder cavity, and the slurry fills the expansion bladder cavity, so that the outer wall of the expansion bladder cavity fits and blocks the grouting hole of the section where it is located, isolating the grouting hole sections where the two vacuum pipe sections are located, and the grouting hole is divided into multiple isolation sections.

[0011] The present invention also discloses a step-by-step and segmented tunnel curtain grouting construction device, comprising the above-mentioned step-by-step and segmented tunnel curtain grouting construction pipe group, and also comprising a plurality of built-in gun barrels, each built-in gun barrel is used to be inserted into a corresponding vacuum tube and a grouting pipe, and each built-in gun barrel comprises:

[0012] The connecting pipe is a multi-section detachably connected pipe structure, which is used to be inserted into the corresponding pipe, with the front end facing the bottom of the pipe, and can move back and forth in each pipe;

[0013] The gun head is a hard tube body, which can be detachably mounted on the front end of the connecting tube; the front end section is solid and closed, and a plurality of connecting holes are opened on the tube body in the middle section;

[0014] There are two isolating pistons, which are spaced apart and sleeved at the front and rear ends of the gun head. The outer diameter is consistent with the inner diameter of the pipe into which it is inserted, and it fits tightly with the pipe wall to seal the vacuum pipe or grouting pipe section between the isolating pistons into a closed space. The isolating piston moves with the movement of the connecting pipe, and the different sections of the vacuum pipe or grouting pipe are sequentially sealed into a closed space.

[0015] The built-in gun barrel is used to sequentially inject water or slurry into the first grouting pipe section, and is also used to sequentially inject grout into each isolation pipe section, and to evacuate each vacuum pipe section.

[0016] Further, it also includes a vacuum suction device for connecting to the built-in gun barrel inserted into the vacuum tube;

[0017] The vacuum suction device includes a vacuum pumping barrel, which includes a liquid storage barrel, which is a vertically placed steel sealed barrel for temporarily storing the pumped liquid; a vacuum pump and a negative pressure gauge are installed at the upper end of the liquid storage barrel;

[0018] The upper and lower parts of the side wall of the liquid storage barrel are respectively provided with a liquid inlet pipe and a liquid discharge pipe connected to the inner cavity of the barrel, and a liquid inlet valve is installed on the liquid inlet pipe; a liquid discharge valve is installed on the liquid discharge pipe; when water is injected to flush the surrounding rock, the liquid inlet pipe is connected to the rear end of a connecting pipe to suck and draw water and fine particles into the liquid storage barrel;

[0019] An observation window is provided on the side wall of the liquid storage barrel and in the area where the liquid inlet pipe is located, for observing the color, properties and flow rate of the liquid flowing into the barrel through the liquid inlet valve, as well as the height of the liquid level in the barrel.

[0020] Furthermore, the lengths of the two grouting pipes are not equal.

[0021] The present invention also discloses a step-by-step and segmented tunnel curtain grouting construction method, using the step-by-step and segmented tunnel curtain grouting construction device mentioned above, the construction method is as follows:

[0022] Step 1: Make grouting holes:

[0023] On the grout-stopping wall, with the tunnel center as the center of the circle, multiple radial extensions are arranged at intervals along the contours of the tunnel vault and the side walls. On each of the same radial extensions, three grouting hole openings, inner, middle and outer, are designed from the inside to the outside, and the angle and depth of each grouting hole are designed; a grouting hole opening on a radial extension is selected to be a grouting hole, and the terminal hole position of the grouting hole in the surrounding rock is obtained; wherein: the terminal holes of the middle and outer grouting holes are located at the terminal cross section of the tunnel section to be reinforced, and the terminal hole of the inner grouting hole is located at the middle cross section of the tunnel section to be reinforced;

[0024] Step 2: Set up vacuum isolation sections in sections:

[0025] Insert a vacuum tube to the bottom of the inner grouting hole, start from the second grouting pipe section at the bottom of the hole, and sequentially retreat to the hole mouth, and sequentially inject slurry into each second grouting pipe section. Under the action of grouting pressure, the slurry overflows the rubber reset sleeve through the one-way plug and enters the expansion bag cavity. The isolation bag sleeve expands and blocks the grouting hole of this section, completing the blocking of the grouting holes at each isolation pipe section.

[0026] Step 3: Inject water to flush the surrounding rock and form a water flow channel in the surrounding rock:

[0027] A built-in gun barrel is inserted into each of the grouting pipes in the middle and outer grouting holes to the bottom, and a built-in gun barrel is inserted into the vacuum tube to the bottom, and the orifice end thereof is connected to a vacuum suction device; the two built-in gun barrels of the middle grouting pipe and the vacuum tube are synchronously retreated in sections toward the orifice end, and clean water is injected into the first grouting pipe section in each section; each vacuum tube section is sucked into a negative pressure state, and a negative pressure zone is formed between the vacuum tube section and the grouting hole, and the pressurized clean water is guided to carry fine particles to the negative pressure zone, and flows into the vacuum tube section and is discharged to the outside of the vacuum tube. During the flow of the clean water, multiple water flow channels are formed in the surrounding rock between the middle grouting hole and the inner grouting hole;

[0028] Repeat the above operation to form multiple water flow channels in the surrounding rock between the outer grouting hole and the inner grouting hole;

[0029] Step 4: Inject chemical slurry to form primary slurry veins:

[0030] Starting from the first grouting pipe section at the bottom of the grouting pipe in the middle and outer grouting holes, the pipes are retreated in sections toward the hole mouth end in sequence, and chemical slurry is injected into each section of the grouting pipe in sequence; at the same time, synchronously with the injection of chemical slurry, starting from the vacuum pipe section at the bottom of the hole, the pipes are retreated in sections in sequence, and each vacuum pipe section is evacuated, so that the chemical slurry in the grouting pipe section on the same cross section as the vacuum pipe section flows into and fills the water flow channel in the surrounding rock, solidifies and forms a primary slurry vein;

[0031] Step 5: Repeat steps 1 to 4 to complete the tunnel curtain grouting.

[0032] Furthermore, in step four, after the primary slurry veins are formed, cement slurry is injected to form composite slurry veins. Specifically, the method of injecting chemical slurry is adopted to inject cement slurry into the channel injected with chemical slurry to form composite slurry veins covered by cement slurry and primary slurry veins.

[0033] Furthermore, the arrangement of the grouting hole openings is as follows: there are multiple inner, middle and outer grouting hole openings, and the number is the same, and the inner, middle and outer grouting hole openings are all arranged in an arch shape along the contour lines of the tunnel vault and side walls.

[0034] Furthermore, the specific process of step two is as follows: inserting a built-in gun barrel into the vacuum tube, the gun head is located in the second grouting pipe section at the bottom of the hole, and the orifice end of the built-in gun barrel is connected to the grouting device; the gun head starts from the bottom of the hole and retreats toward the orifice in sequence, and is located in each second grouting pipe section in sequence; in each second grouting pipe section, two isolation pistons are tightly fitted to the inner wall of the second grouting pipe section, forming a closed space between the two isolation pistons; in each second grouting pipe section, slurry is injected from the gun head, and under the action of the grouting pressure, the slurry enters the expansion sac cavity.

[0035] Furthermore, the specific process of step three is as follows:

[0036] Insert an internal gun barrel into the middle grouting pipe, and move the gun head to the first grouting pipe section at the bottom. Starting from the first grouting pipe section at the bottom, the gun head retreats to the orifice end in sequence and is located in each first grouting pipe section in sequence. In each first grouting pipe section, two isolation pistons are tightly fitted to the inner wall of the first grouting pipe section to form a closed space between the two isolation pistons. Inject water into the internal gun barrel, inject water into the first grouting pipe section from the gun head, push open the one-way plug and enter the grouting hole from the overflow hole.

[0037] At the same time, the vacuum suction device is connected to the built-in gun barrel in the vacuum tube, and the gun head is located in the vacuum tube section at the bottom of the hole. Synchronously with the injection of clean water, the gun head retreats toward the hole end in turn and is located in each vacuum tube section in turn; in each vacuum tube section, a closed space is formed between the two isolation pistons and the section with vents in the vacuum tube section. The vacuum suction device draws suction to form a negative pressure zone between the closed space and the grouting hole, guiding the pressurized clean water at the first grouting tube section of the corresponding section to carry fine particles to the negative pressure zone, and flows into the vacuum tube section and is discharged to the outside of the vacuum tube. During the flow of clean water, multiple water flow channels are formed in the surrounding rock between the grouting holes on the inner side of the middle grouting hole.

[0038] Furthermore, the specific process of step 4 is as follows:

[0039] Insert an internal gun barrel into the grouting pipe in the middle grouting hole, and the gun head is located at the first grouting pipe section at the bottom, and the two isolation pistons are tightly fitted to the inner wall of the first grouting pipe section, forming a closed space between the two isolation pistons; at the same time, insert another internal gun barrel into the vacuum tube, and the gun head is located at the vacuum tube section at the bottom, and in each vacuum tube section, a closed space is formed between the two isolation pistons and the vacuum tube section with a vent hole;

[0040] The two built-in gun barrels drive the gun heads to synchronously retreat to the hole end in sequence, and from the bottom of the hole to the hole mouth, the following operations are performed in the first grouting pipe section and the vacuum pipe section in sequence: chemical slurry is injected into the first grouting pipe section, and at the same time, the vacuum suction device sucks to vacuumize the closed space, and the chemical slurry flows into the water flow channel. When the water flow channel is filled with chemical slurry, the slurry is sucked into the vacuum suction device, and the chemical slurry grouting is completed;

[0041] The above operations are adopted to complete the cement slurry grouting.

[0042] The beneficial effects of the present invention are: 1. The formed water flow channel serves as the subsequent grouting channel, and the grouting is carried out in sections. After the chemical slurry is injected first, the contact surface between the chemical slurry stone body and the formation becomes a weak surface. Under the action of the grouting pressure, the cement slurry undergoes stress concentration along this surface, and then it is easy to split and flow, thereby overcoming the resistance of the original formation and greatly increasing the injection amount of the slurry. 2. The slurry veins formed by the hardening of the slurry are in a network shape, replacing the large-volume block slurry veins that often appear in conventional grouting schemes, which reinforces the formation more evenly and has a better grouting effect. 3. The slurry is injected into the grouting channel and enters the formation through the grouting channel, which better controls the grouting range, improves the effective utilization rate of the slurry, and saves costs. 4. By flushing out a certain amount of fine particles in the formation in the water flow channel and replacing them with slurry filling, the disturbance to the formation during grouting is relatively small, which is conducive to ensuring the safety of surrounding buildings (structures). BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of a step-by-step and segmented tunnel curtain grouting construction pipe group;

[0044] Figure 2 It is a structural schematic diagram of the pipe head;

[0045] Figure 3 It is a schematic diagram of the structure of the first grouting pipe section and the second grouting pipe section;

[0046] Figure 4 It is a structural schematic diagram of the vacuum tube section;

[0047] Figure 5 It is a structural schematic diagram of the isolation pipe section;

[0048] Figure 6 It is a schematic diagram of the structure of the built-in barrel;

[0049] Figure 7 It is a schematic diagram of the structure of the vacuum suction device;

[0050] Figure 8 A 3D schematic diagram of a step-by-step and segmental tunnel curtain grouting;

[0051] Fig. 9 A step-by-step and segmented tunnel curtain grouting scheme, longitudinal section view, schematic diagram of grouting hole opening arrangement;

[0052] Fig.10 A longitudinal section view of a grouting pipe and a vacuum pipe inserted into a grouting hole;

[0053] Fig.11 This is a schematic diagram of the structure of the water flow channel formed in the surrounding rock;

[0054] Fig.12 This is a schematic diagram of the structure for injecting chemical slurry into the surrounding rock;

[0055] Fig.13 This is a schematic diagram of the structure for injecting cement slurry into the surrounding rock;

[0056] Among them: 1. Grouting pipe;

[0057] 2. Vacuum tube;

[0058] 3. Tube head;

[0059] 4. Overflow hole; 4-1. First grouting pipe section; 4-2. Second grouting pipe section; 41. One-way plug; 42. Rubber reset sleeve;

[0060] 5. Vacuum pipe section; 51. Ventilation hole; 52. Isolation net;

[0061] 6. Isolation bag sleeve; 6a. Isolation pipe section; 61. Sealing hoop; 62. Expansion sleeve;

[0062] 7. Built-in gun barrel; 71. Gun head; 72. Isolation piston; 73. Connecting pipe; 74. Quick connector; 75. Connecting hole;

[0063] 8. Vacuum extraction bucket; 81. Liquid storage bucket; 82. Vacuum pump; 83. Negative pressure gauge; 84. Liquid inlet valve; 85. Liquid discharge valve; 86. Observation window. DETAILED DESCRIPTION

[0064] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0065] The present invention discloses a step-by-step and segment-by-segment tunnel curtain grouting construction pipe group, such as Figure 1 The diagram includes multiple sets of construction kits, each of which includes two grouting pipes 1 and a vacuum tube 2, which are used to be inserted into grouting holes of different depths; the lengths of the two grouting pipes 1 are not equal. Each grouting pipe 1 is composed of multiple first grouting pipe sections 4-1 connected in sequence.

[0066] like Figure 3 and 5 As shown, the vacuum tube 2 is composed of a plurality of interconnected vacuum tube segments 5 and a plurality of isolation tube segments 6a connected at intervals, and the vacuum tube segment 5 is connected at the front end, and the middle of each vacuum tube segment 5 is connected to the grouting hole; each isolation tube segment 6a is a double-layer casing structure, including a second grouting tube segment 4-2 and an isolation bag sleeve 6 arranged together inside and outside, and the two ends of the isolation bag sleeve 6 are tightly fitted with the outer walls of the two ends of the second grouting tube segment 4-2 to form an expansion bag cavity with two ends closed; as shown Figure 2 As shown, the front ends of the first grouting pipe section 4-1 and the vacuum pipe section 5 at the front end are each connected to a conical closed pipe head 3, and the front end of the pipe head 3 is closed. When inserting the grouting pipe 1 and the vacuum pipe 2 into the grouting hole, the setting of the conical pipe head 3 is more convenient to guide forward and is not easy to be damaged. Figure 4As shown, a vent hole 51 is provided in the middle of the vacuum pipe section 5, and an isolation net 52 is wrapped around the outer side of the pipe wall at that location to prevent large particles of mud and sand from entering therein.

[0067] Each isolation bag sleeve 6 includes an expansion sleeve 62 and two sealing hoops 61, both of which are hollow cylindrical structures, wherein the sealing hoop 61 is made of PVC hard plastic material, and the expansion sleeve 62 is made of high-elastic rubber material. The sealing hoop 61 is located at the expansion sleeve 62 and is tightly bonded together at the ends through heat processing to form an integral hollow isolation bag sleeve 6 with sealing hoops 61 at both ends and an expansion sleeve 62 in the middle.

[0068] The inner diameter of the sealing hoop 61 matches the outer diameter of the second grouting pipe section 4-2, and can be slid outside the second grouting pipe section 4-2. The isolation bag 6 is inserted from one end of the second grouting pipe section 4-2 and finally wraps the second grouting pipe section 4-2. Glue is applied to the outer diameter of both ends of the second grouting pipe section 4-2 to bond and fix the sealing hoop 61 so that it no longer slides and forms a seal.

[0069] like Figure 3 As shown, the first grouting pipe section 4-1 and the second grouting pipe section 4-2 are both made of PVC hard plastic material, and each entire pipe section has a uniform inner diameter, one end of the pipe is provided with an external thread, and the other end is provided with an internal thread, which is used for the combined connection of each pipe section. The middle section of each first grouting pipe section 4-1 and the second grouting pipe section 4-2 is a small diameter section, and a rubber reset sleeve 42 is sleeved on the small diameter section. The setting of the small diameter section is used to limit the sliding of the rubber reset sleeve 42. For the second grouting pipe section 4-2, it is also used to reduce the overall outer diameter of the second grouting pipe section 4-2 after the rubber reset sleeve 42 is installed, so as to facilitate the subsequent insertion of the isolation bag sleeve 6.

[0070] On the outer wall of the small diameter section, a plurality of overflow holes 4 are arranged at intervals around the circumference. Each overflow hole 4 is in the shape of a truncated cone with a larger outer end and a smaller inner end from the outside to the inside. Each overflow hole 4 is provided with a one-way plug 41 of the same shape. The one-way plug 41 is made of rubber. Under the grouting pressure, each one-way plug 41 can move outward in the overflow hole 4, and the outer end pushes up the rubber reset sleeve 42 to form an overflow channel connected at both ends; and when there is no grouting pressure, the rubber reset sleeve 42 shrinks to close the overflow channel;

[0071] In the isolation pipe section 6a, the overflow channel is connected to the expansion bladder cavity, and the slurry fills the expansion bladder cavity, so that the outer wall of the expansion bladder cavity fits and blocks the grouting hole in its section, isolating the grouting hole sections where the two alternate vacuum pipe sections 5 are located, and dividing the grouting hole into multiple isolation sections.

[0072] The present invention also discloses a step-by-step and segment-by-segment tunnel curtain grouting construction device, comprising the step-by-step and segment-by-segment tunnel curtain grouting construction pipe group, such as Figure 6As shown, it also includes a plurality of built-in gun barrels 7, each built-in gun barrel 7 is used to be inserted into the corresponding vacuum tube 2 and grouting tube 1, and each built-in gun barrel 7 includes: a connecting tube 73 is used to be inserted into the corresponding tube, with the front end facing the bottom of the tube and can move back and forth in each tube; a tube body structure with multiple sections that can be detachably connected, and each connecting tube 73 is connected by a quick connector 74; a gun head 71 is a hard tube body that can be detachably installed on the front end of the connecting tube 73; a front end section thereof is solid and closed, and a plurality of connecting holes 75 are opened on the tube body of the middle section.

[0073] There are two isolating pistons 72, which are spaced apart and sleeved at the front and rear ends of the gun head 71, that is, the part of the gun head 71 with the communicating hole 75 is located between the two isolating pistons 72, and the outer diameter of the isolating piston 72 is consistent with the inner diameter of the pipe into which it is inserted, and it fits tightly with the pipe wall to seal the vacuum pipe 2 or the grouting pipe 1 section between the isolating pistons 72 into a closed space. The isolating piston 72 moves with the movement of the connecting pipe 73, and the different sections of the vacuum pipe 2 or the grouting pipe 1 are sequentially sealed into a closed space;

[0074] The built-in gun barrel 7 is used to sequentially inject water or slurry into the first grouting pipe section 4 - 1 , and is also used to sequentially inject grout into each isolation pipe section 6 a , and to evacuate each vacuum pipe section 5 .

[0075] like Figure 7 As shown, the above-mentioned step-by-step and segmented tunnel curtain grouting construction device also includes a vacuum suction device for connecting to the built-in gun barrel 7 inserted into the vacuum tube 2.

[0076] The vacuum suction device includes a vacuum suction barrel 8, which includes a liquid storage barrel 81, which is a vertically placed steel sealed barrel. When a vacuum is formed in the barrel, it can resist the external atmospheric pressure without deformation. Its volume is not less than 1m 3 , used for temporary storage of pumped liquid; a vacuum pump 82 and a negative pressure gauge 83 are installed at the upper end of the liquid storage barrel 81; the vacuum pump 82 is connected to the inside of the liquid storage barrel 81, used to pump out the air in the barrel to form a vacuum negative pressure. The negative pressure gauge 83 is connected to the inside of the liquid storage barrel 81, used to monitor the vacuum degree in the barrel.

[0077] The upper and lower parts of the side wall of the liquid storage barrel 81 are respectively provided with a liquid inlet pipe and a liquid discharge pipe connected to the inner cavity of the barrel, and a liquid inlet valve 84 is installed on the liquid inlet pipe; a liquid discharge valve 85 is installed on the liquid discharge pipe, and the liquid discharge valve 85 is a large-diameter ball valve. When water is injected to flush the surrounding rock, the liquid inlet pipe is connected to the rear end of a connecting pipe 73 to suck and draw water and fine particles into the liquid storage barrel 81.

[0078] An observation window 86 is provided on the side wall of the liquid storage barrel 81 and located in the area where the liquid inlet pipe is located, for observing the color, properties and flow rate of the liquid flowing into the barrel through the liquid inlet valve 84, as well as the height of the liquid level in the barrel.

[0079] The present invention discloses a step-by-step and segmented tunnel curtain grouting construction method, using the above-mentioned step-by-step and segmented tunnel curtain grouting construction device, the construction method is as follows:

[0080] Step 1: Make grouting holes:

[0081] On the grouting wall, with the tunnel center as the center of the circle, multiple radial extensions are set at intervals along the contours of the tunnel vault and side walls. On each radial extension, three grouting hole openings, inner, middle and outer, are designed from the inside to the outside, and the angle and depth of each grouting hole are designed; a grouting hole opening on a radial extension is selected to make a grouting hole, and the final hole position of the grouting hole in the surrounding rock is obtained; among them: the final holes of the middle and outer grouting holes are located at the terminal cross section of the tunnel section to be reinforced, and the final hole of the inner grouting hole is located at the middle cross section of the tunnel section to be reinforced. The angles of two adjacent radial extensions are the same, such as Fig. 9 As shown, the arrangement of the grouting hole openings is as follows: there are multiple inner, middle and outer grouting hole openings, and the number is the same, and the inner, middle and outer grouting hole openings are all arranged in an arch shape along the contour lines of the tunnel vault and side walls.

[0082] The inner, middle and outer three grouting holes on the same radial extension are taken as a group. The length of this cycle grouting reinforcement section is 20m. The tunnel cross section at the end of the length is within the final length cross section. The tunnel cross section at the middle of the length of this cycle grouting reinforcement section (i.e. 10m) is the middle cross section. The end hole position of the inner hole is the intersection of the radial plane of this group and the tunnel excavation contour line in the final length cross section. The end hole position of the middle hole is the intersection of the radial plane and the radial reinforcement range contour line in the final length cross section. The end hole position of the outer grouting hole is the intersection of the radial plane of this group and the reinforcement range contour line in the middle cross section.

[0083] Step 2: Set up vacuum isolation sections in sections:

[0084] Insert the vacuum tube 2 into the inner grouting hole to the bottom of the hole, and start from the second grouting pipe section 4-2 at the bottom of the hole and retreat to the hole mouth end in sequence, and inject slurry into each second grouting pipe section 4-2 in sequence. Under the action of grouting pressure, the slurry overflows from the rubber reset sleeve 42 through the one-way plug 41 and enters the expansion bag cavity. The isolation bag sleeve 6 expands and blocks the grouting hole of this section, thereby completing the blocking of the grouting holes at each isolation pipe section 6a.

[0085] The specific process of step 2 is as follows: insert a built-in gun barrel 7 into the vacuum tube 2, and the gun head 71 is located at the second grouting pipe section 4-2 at the bottom of the hole, and the orifice end of the built-in gun barrel 7 is connected to the grouting device; the gun head 71 starts from the bottom of the hole and retreats to the orifice in sequence, and is located in each second grouting pipe section 4-2 in sequence; in each second grouting pipe section 4-2, two isolation pistons 72 are tightly fitted to the inner wall of the second grouting pipe section 4-2, and a closed space is formed between the two isolation pistons 72; in each second grouting pipe section 4-2, slurry is injected by the gun head 71, and the slurry is a cement-water glass double liquid slurry. Under the action of grouting pressure, the slurry enters and fills the expansion bag cavity, and the isolation bag sleeve 6 expands to fill the grouting hole of its section, so that the grouting hole outside the vacuum tube 2 forms a plurality of mutually isolated segments, that is, the grouting hole sections where the two alternate vacuum pipe sections 5 are located are isolated.

[0086] The purpose of forming multiple mutually isolated sections of the grouting holes outside the vacuum tube 2 is that when vacuum suction is used to attract water, the gravity source can be divided into multiple sections, and the distance to the grouting water source of each section can be shortened, thereby enhancing the vacuum suction effect, so that no missing areas of the surrounding rock within the entire length range will appear, and it is also convenient to better control the impact range of the entire grouting construction process and avoid material waste.

[0087] Step 3: Inject water to flush the surrounding rock and form a water flow channel in the surrounding rock:

[0088] An internal gun barrel 7 is inserted into each of the grouting pipes 1 in the middle and outer grouting holes to the bottom, and an internal gun barrel 7 is inserted into the vacuum tube 2 to the bottom, and the orifice end thereof is connected to a vacuum suction device; the two internal gun barrels 7 of the middle grouting pipe 1 and the vacuum tube 2 are simultaneously withdrawn in sections toward the orifice end, and in each section, clean water is injected into the first grouting pipe section 4-1; each vacuum tube section 5 is sucked into a negative pressure state, and a negative pressure zone is formed between the vacuum tube section 5 and the grouting hole, and the pressurized clean water is guided to carry fine particles to flow to the negative pressure zone, and flows into the vacuum tube section 5, and is discharged to the outside of the vacuum tube 2. During the flow of the clean water, a plurality of water flow channels are formed in the surrounding rock between the middle grouting hole and the inner grouting hole; the above operation is repeated to form a plurality of water flow channels in the surrounding rock between the outer grouting hole and the inner grouting hole. The formed water flow channel serves as the channel for subsequent grouting. It is formed by flushing out a certain amount of fine particles in the formation, and is subsequently replaced with slurry filling. The disturbance to the formation is relatively small, which is conducive to ensuring the safety of surrounding buildings.

[0089] The specific process of step three is as follows:

[0090] An internal gun barrel 7 is inserted into the middle grouting pipe 1, and the gun head 71 reaches the first grouting pipe section 4-1 at the bottom. Starting from the first grouting pipe section 4-1 at the bottom, the gun head 71 retreats toward the orifice end in sequence and is located in each first grouting pipe section 4-1 in sequence. In each first grouting pipe section 4-1, two isolation pistons 72 fit tightly against the inner wall of the first grouting pipe section 4-1, forming a closed space between the two isolation pistons 72; water is injected into the internal gun barrel 7, and is injected into the closed space in the first grouting pipe section 4-1 by the gun head 71; as the water injection pressure increases, the water flow pushes open the one-way plug 41 and the rubber reset sleeve 41 and is injected into the surrounding rock, forming a pressurized water source at this point.

[0091] At the same time, the vacuum suction device is connected to the built-in gun barrel 7 in the vacuum tube 2, and the gun head 7 is located in the vacuum tube section 5 at the bottom of the hole. Synchronously with the water injection, the gun head 71 retreats toward the hole mouth end in turn and is located in each vacuum tube section 5 in turn; in each vacuum tube section 5, a closed space is formed between the two isolation pistons 72 and the section of the vacuum tube section 5 with the vent 51, the liquid inlet pipe of the vacuum extraction barrel 8 is connected to the built-in gun barrel 7, the vacuum pump 82 is turned on to start extraction, and the vacuum negative pressure is controlled at about 1 MPa according to the indication of the negative pressure gauge 83. The position of the gun head 71 is connected to the surrounding rock through the vent 51 and the isolation net 52. A vacuum negative pressure source is formed in the surrounding rock at this section of the grouting holes, which guides the clean water output by the gun head 71 to flow here in one direction. At the same time, some fine particles are entrained by the water flow and pass through the isolation net 52, are sucked into the built-in gun barrel 7 and finally flow into the vacuum pumping bucket 8, and multiple water flow channels are formed in the surrounding rock between the middle grouting hole and the inner grouting hole. With the continuous loss of fine particles in the surrounding rock, the water flow channels are further expanded and unblocked.

[0092] Watch the water flow into the liquid storage barrel 81 through the liquid inlet valve 84 through the observation window 86. When the water becomes clearer, does not contain fine particles such as mud and sand, and the water flow rate drawn exceeds 1 / 2 of the water flow rate injected, a sufficiently smooth water flow channel has been formed in this section of the stratum. When moving backward in sections, turn off the grouting machine to stop water injection, and close the liquid inlet valve 84 of the vacuum pumping barrel 8. Pull the built-in gun barrel 7 toward the orifice to the next adjacent pipe section, and form multiple water flow channels in the surrounding rock between the outer grouting hole and the inner grouting hole. Figure 8 , 10 and 11.

[0093] During the operation, if the water level in the liquid storage tank 81 exceeds 2 / 3 by observing through the observation window 86, the water injection and pumping work is suspended, the drain valve 85 is opened to discharge water and sediment, and then the drain valve 85 is closed to resume the pumping work.

[0094] Step 4: Inject chemical slurry to form primary slurry veins:

[0095] like Fig.12As shown, the first grouting pipe section 4-1 at the bottom of the grouting pipe 1 in the middle and outer grouting holes is retreated in sections toward the hole mouth, and chemical slurry is injected into each section of the grouting pipe in sequence; at the same time, synchronously with the injection of chemical slurry, the vacuum pipe section 5 at the bottom of the hole is retreated in sections in sequence, and each section of the vacuum pipe section 5 is evacuated, so that the chemical slurry in the grouting pipe section on the same cross section as the vacuum pipe section 5 flows into and fills the water flow channel in the surrounding rock, solidifies to form a primary slurry vein. In step three, the chemical slurry with low strength and slightly poor diffusivity is fully filled in the surrounding rock along the water flow channel by using segmented retreating pressure grouting and vacuum negative pressure suction, and an extended network of slurry veins is formed after hardening. At the same time, the slurry vein forms a contact surface with the surrounding rock, but its mechanical properties are weak. In order to improve the stability of the surrounding rock, cement slurry needs to be injected again.

[0096] like Fig.13 As shown, after the chemical slurry solidifies to form the primary slurry vein, cement slurry is injected to form a composite slurry vein, specifically: the method of injecting chemical slurry is adopted, from the grouting pipe 1 in the middle grouting hole to the grouting pipe 1 in the outer grouting hole, and cement slurry is injected into the channel injected with chemical slurry to form a composite slurry vein covered by cement slurry and primary slurry vein. Cement slurry has high strength and poor diffusion. When it contacts the surface of the chemical slurry vein, splitting grouting occurs on the surface of the chemical slurry vein, and the fluidity is good, which increases the grouting amount. In the surrounding rock, the surrounding rock is squeezed and compacted to form a composite network slurry vein with cement slurry vein wrapped outside and chemical slurry vein sandwiched inside.

[0097] The specific process of step 4 is as follows:

[0098] A built-in gun barrel 7 is inserted into the grouting pipe 1 in the middle grouting hole, and the gun head 71 is located at the first grouting pipe section 4-1 at the bottom, and two isolation pistons 72 are tightly fitted to the inner wall of the first grouting pipe section 4-1, and a closed space is formed between the two isolation pistons 72; at the same time, another built-in gun barrel 7 is inserted into the vacuum tube 2, and the gun head 71 is located at the vacuum pipe section 5 at the bottom, and in each vacuum pipe section 5, a closed space is formed between the two isolation pistons 72 and the vacuum pipe section 5 with the vent hole 51;

[0099] The two built-in gun barrels 7 drive the gun head 71 to synchronously retreat to the orifice end in turn, from the bottom of the hole to the orifice, and perform the following operations in each section of the first grouting pipe section 4-1 and the vacuum pipe section 5 in turn: inject chemical slurry into the first grouting pipe section 4-1, and at the same time, the vacuum suction device sucks, vacuumizes the closed space, and the chemical slurry flows into the water flow channel. When the water flow channel is filled with chemical slurry, the slurry is sucked into the vacuum suction device, and the chemical slurry grouting is completed. Specifically, through and through the observation window 86, pay attention to the liquid flowing into the liquid storage barrel 81 through the liquid inlet valve 84. When it is found that there is chemical slurry flowing out, the water flow channel of this section of the formation has been filled with chemical slurry. During the working process, observe through the observation window 86. If the water level in the liquid storage barrel 81 exceeds 2 / 3, grouting and pumping are suspended, and the drain valve 85 is opened to discharge water and waste slurry, and then the drain valve 85 is closed to resume work.

[0100] Step 5: Repeat steps 1 to 4 to complete the tunnel curtain grouting. Finally, an "arch"-shaped reinforcement area is formed along the area outside the tunnel excavation contour line.

[0101] In the present invention, the following method is adopted: setting an isolation section - water injection - chemical slurry injection - cement slurry injection, distributed segmented tunnel curtain grouting, after the chemical slurry solidifies, the slurry stone body forms a contact surface with the stratum, but because the strength of the chemical slurry stone body is very low (unconfined compressive strength is about 0.5MPa), the surrounding rock reinforcement effect is poor at this time, and further treatment is required, and then cement slurry is injected to form a composite slurry vein, specifically: adopt the method of injecting chemical slurry, and inject cement slurry into the channel injected with chemical slurry to form a composite slurry vein covered by cement slurry and primary slurry vein. After the chemical slurry is injected, the contact surface between the chemical slurry stone body and the stratum becomes a weak surface, and the cement slurry generates stress concentration along this surface under the action of the grouting pressure, and then it is easy to split and flow, thereby overcoming the resistance of the original stratum, greatly increasing the injection amount of slurry, forming a composite slurry vein with cement slurry vein wrapped outside and chemical slurry vein sandwiched inside, thereby completing the grouting reinforcement of this section of stratum.

Claims

1. A step-by-step and segmented tunnel curtain grouting construction method, characterized in that: A step-by-step and segmented tunnel curtain grouting construction device is used, the device comprising a plurality of construction kits and a plurality of built-in gun barrels (7), each of the construction kits comprising two grouting pipes (1) and a vacuum pipe (2) for being inserted into grouting holes of different depths; wherein: Each of the grouting pipes (1) is composed of a plurality of first grouting pipe sections (4-1) connected in sequence; The vacuum tube (2) is composed of a plurality of interconnected vacuum tube sections (5) and a plurality of isolation tube sections (6a) connected at intervals, and the vacuum tube section (5) is connected at the front end, and the middle of each vacuum tube section (5) is connected to the grouting hole; each isolation tube section (6a) is a double-layer casing structure, comprising a second grouting tube section (4-2) and an isolation bag sleeve (6) arranged together inside and outside, and the two ends of the isolation bag sleeve (6) are tightly fitted with the outer walls of the two ends of the second grouting tube section (4-2) to form an expansion bag cavity with two ends closed; the front ends of the first grouting tube section (4-1) and the vacuum tube section (5) at the front end are closed; The middle section of each of the first grouting pipe section (4-1) and the second grouting pipe section (4-2) is a small diameter section, and a rubber reset sleeve (42) is sleeved on the small diameter section; on the outer wall of the small diameter section, a plurality of overflow holes (4) are arranged at intervals in a circumferential direction, and each of the overflow holes (4) is in the shape of a truncated cone with a larger outer end and a smaller inner end from the outside to the inside, and each of the overflow holes (4) is provided with a one-way plug (41) of the same shape; under grouting pressure, each of the one-way plugs (41) can move outward in the overflow hole (4), and the outer end pushes up the rubber reset sleeve (42), forming an overflow channel with two ends connected, which is connected to the grouting hole; and when there is no grouting pressure, the rubber reset sleeve (42) contracts to close the overflow channel; In the isolation pipe section (6a), the overflow channel is connected to the expansion bladder cavity, and the slurry fills the expansion bladder cavity, so that the outer wall of the expansion bladder cavity fits and blocks the grouting hole of the section where it is located, and the grouting hole sections where the two vacuum pipe sections (5) are located are separated, and the grouting hole is divided into a plurality of isolation sections; Each of the built-in gun barrels (7) is used to be inserted into a corresponding vacuum tube (2) and a grouting tube (1); The construction method is as follows: Step 1: Make grouting holes: On the grout-stopping wall, with the tunnel center as the center of the circle, multiple radial extensions are arranged at intervals along the contours of the tunnel vault and the side walls. On each of the same radial extensions, three grouting hole openings, inner, middle and outer, are designed from the inside to the outside, and the angle and depth of each grouting hole are designed; a grouting hole opening on a radial extension is selected to be a grouting hole, and the terminal hole position of the grouting hole in the surrounding rock is obtained; wherein: the terminal holes of the middle and outer grouting holes are located at the terminal cross section of the tunnel section to be reinforced, and the terminal hole of the inner grouting hole is located at the middle cross section of the tunnel section to be reinforced; Step 2: Set up vacuum isolation sections in sections: Insert a vacuum tube (2) into the inner grouting hole to the bottom of the hole, and start from the second grouting pipe section (4-2) at the bottom of the hole and sequentially retreat toward the hole mouth, and sequentially inject slurry into each second grouting pipe section (4-2); under the action of the grouting pressure, the slurry overflows from the rubber reset sleeve (42) through the one-way plug (41) and enters the expansion bag cavity, and the isolation bag sleeve (6) expands to block the grouting hole of this section, thereby completing the blocking of the grouting holes at each isolation pipe section (6a); Step 3: Inject water to flush the surrounding rock and form a water flow channel in the surrounding rock: A built-in gun barrel (7) is inserted into each of the grouting pipes (1) in the middle and outer grouting holes to the bottom, and a built-in gun barrel (7) is inserted into the vacuum pipe (2) to the bottom, and the orifice end thereof is connected to a vacuum suction device; the two built-in gun barrels (7) of the middle grouting pipe (1) and the vacuum pipe (2) are synchronously moved back in sections toward the orifice end, and clean water is injected into the first grouting pipe section (4-1) in each section; each of the vacuum pipe sections (5) is sucked into a negative pressure state, and a negative pressure zone is formed between the vacuum pipe section (5) and the grouting hole, and the pressurized clean water is guided to carry fine particles to the negative pressure zone, and flows into the vacuum pipe section (5) and is discharged to the outside of the vacuum pipe (2); during the flow of the clean water, a plurality of water flow channels are formed in the surrounding rock between the middle grouting hole and the inner grouting hole; Repeat the above operation to form multiple water flow channels in the surrounding rock between the outer grouting hole and the inner grouting hole; Step 4: Inject chemical slurry to form primary slurry veins: Starting from the first grouting pipe section (4-1) at the bottom of the grouting pipe (1) in the middle and outer grouting holes, the grouting pipes (1) are retreated in sections toward the hole mouth end in sequence, and chemical slurry is injected into each section of the grouting pipe in sequence; at the same time, synchronously with the injection of chemical slurry, starting from the vacuum pipe section (5) at the bottom of the hole, the grouting pipes are retreated in sections in sequence, and each section of the vacuum pipe section (5) is evacuated, so that the chemical slurry in the grouting pipe section on the same cross section as the vacuum pipe section (5) flows into and fills the water flow channel in the surrounding rock, solidifies and forms a primary slurry vein; Step 5. Repeat steps 1 to 4 to complete the tunnel curtain grouting.

2. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 1, characterized in that: Each of the built-in gun barrels (7) comprises: The connecting tube (73) is a multi-section detachably connected tube structure, which is used to be inserted into the corresponding tube, with the front end facing the bottom of the tube and can move forward and backward in each tube; The gun head (71) is a hard tube body, which can be detachably mounted on the front end of the connecting tube (73); the front end section thereof is solid and closed, and a plurality of communication holes (75) are opened on the tube body in the middle section; There are two isolating pistons (72) which are spaced apart and sleeved at the front and rear ends of the gun head (71). The outer diameter of the isolating pistons (72) is consistent with the inner diameter of the tube into which the isolating pistons (72) are inserted and they are tightly fitted to the tube wall so as to seal the vacuum tube (2) or the grouting tube (1) section between the isolating pistons (72) into a closed space. The isolating pistons (72) move with the movement of the connecting tube (73) so as to sequentially seal different sections of the vacuum tube (2) or the grouting tube (1) into a closed space. The built-in gun barrel (7) is used to sequentially inject water or slurry into the first grouting pipe section (4-1), and is also used to sequentially inject grout into each isolation pipe section (6a), and to evacuate each vacuum pipe section (5).

3. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 2, characterized in that: It also includes a vacuum suction device for connecting to a built-in gun barrel (7) inserted into the vacuum tube (2); The vacuum suction device comprises a vacuum suction barrel (8), and the vacuum suction barrel (8) comprises a liquid storage barrel (81), which is a vertically placed steel sealed barrel and is used to temporarily store the suction liquid; a vacuum pump (82) and a negative pressure gauge (83) are installed at the upper end of the liquid storage barrel (81); A liquid inlet pipe and a liquid discharge pipe communicating with the inner cavity of the barrel are respectively arranged at the upper and lower parts of the side wall of the liquid storage barrel (81); a liquid inlet valve (84) is installed on the liquid inlet pipe; and a liquid discharge valve (85) is installed on the liquid discharge pipe. When water is injected to flush the surrounding rock, the liquid inlet pipe is connected to the rear end of a connecting pipe (73) to suck and draw water and fine particles into the liquid storage barrel (81); An observation window (86) is provided on the side wall of the liquid storage barrel (81) and located in the area where the liquid inlet pipe is located, for observing the color, properties and flow rate of the liquid flowing into the barrel through the liquid inlet valve (84), as well as the height of the liquid level in the barrel.

4. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 3, characterized in that: The two grouting pipes (1) are not equal in length.

5. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 4, characterized in that: In step 4, after the primary slurry veins are formed, cement slurry is injected to form composite slurry veins. Specifically, the method of injecting chemical slurry is adopted to inject cement slurry into the channel injected with chemical slurry to form composite slurry veins covered by cement slurry and primary slurry veins.

6. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 5, characterized in that: The arrangement of the grouting hole openings is as follows: there are multiple inner, middle and outer grouting hole openings, and the number is the same, and the inner, middle and outer grouting hole openings are all arranged in an arch shape along the contour lines of the tunnel vault and side walls.

7. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 6, characterized in that: The specific process of step 2 is as follows: inserting a built-in gun barrel (7) into the vacuum tube (2), with the gun head (71) located in the second grouting pipe section (4-2) at the bottom of the hole, and the orifice end of the built-in gun barrel (7) being connected to the grouting device; the gun head (71) moves from the bottom of the hole to the orifice in sequence, and is located in each of the second grouting pipe sections (4-2) in sequence; in each of the second grouting pipe sections (4-2), two isolation pistons (72) are tightly fitted to the inner wall of the second grouting pipe section (4-2), and a closed space is formed between the two isolation pistons (72); slurry is injected into each of the second grouting pipe sections (4-2) by the gun head (71), and the slurry enters the expansion sac cavity under the action of the grouting pressure.

8. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 7, characterized in that: The specific process of step three is as follows: Inserting an internal gun barrel (7) into the middle grouting pipe (1), with the gun head (71) reaching the first grouting pipe section (4-1) at the bottom, and starting from the first grouting pipe section (4-1) at the bottom, the gun head (71) sequentially retreats toward the orifice end and is sequentially located in each of the first grouting pipe sections (4-1), and in each of the first grouting pipe sections (4-1), two isolation pistons (72) are tightly fitted to the inner wall of the first grouting pipe section (4-1), and a closed space is formed between the two isolation pistons (72); injecting water into the internal gun barrel (7), and injecting water into the first grouting pipe section (4-1) from the gun head (71), pushing open the one-way plug (41) and entering the grouting hole from the overflow hole (4); At the same time, the vacuum suction device is connected to the built-in gun barrel (7) in the vacuum tube (2), and the gun head (71) is located in the vacuum tube section (5) at the bottom of the hole. Synchronously with the injection of clean water, the gun head (71) retreats toward the hole mouth end in sequence and is located in each of the vacuum tube sections (5) in sequence. In each of the vacuum tube sections (5), a closed space is formed between the two isolation pistons (72) and the section of the vacuum tube section (5) with the vent hole (51). The vacuum suction device suctions to form a negative pressure zone between the closed space and the grouting hole, and guides the pressurized clean water at the first grouting tube section (4-1) of the corresponding section to carry fine particles to the negative pressure zone, and flows into the vacuum tube section (5) and is discharged to the outside of the vacuum tube (2). During the flow of the clean water, a plurality of water flow channels are formed in the surrounding rock between the grouting holes inside the middle grouting hole.

9. A step-by-step and segmented tunnel curtain grouting construction method as claimed in claim 8, characterized in that: The specific process of step 4 is as follows: A built-in gun barrel (7) is inserted into the grouting pipe (1) in the middle grouting hole, and the gun head (71) is located at the first grouting pipe section (4-1) at the bottom, and two isolation pistons (72) are tightly fitted to the inner wall of the first grouting pipe section (4-1), so that a closed space is formed between the two isolation pistons (72); at the same time, another built-in gun barrel (7) is inserted into the vacuum tube (2), and the gun head (71) is located at the vacuum tube section (5) at the bottom, and in each of the vacuum tube sections (5), a closed space is formed between the two isolation pistons (72) and the section of the vacuum tube section (5) with the vent hole (51); The two built-in gun barrels (7) drive the gun head (71) to synchronously retreat toward the hole end in sequence, and from the bottom of the hole to the hole mouth, the following operations are performed in the first grouting pipe section (4-1) and the vacuum pipe section (5) in sequence: chemical slurry is injected into the first grouting pipe section (4-1), and at the same time, the vacuum suction device sucks to evacuate the closed space, and the chemical slurry flows into the water flow channel. When the water flow channel is filled with chemical slurry, the slurry is sucked into the vacuum suction device, and the chemical slurry grouting is completed; The above operations are adopted to complete the cement slurry grouting.

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