Pressure-adjustable bidirectional packer and method

Abstract

The application discloses a pressure-adjustable bidirectional packer grouting device and method, and relates to the field of drilling engineering. The device comprises a connecting unit, the rear end of the connecting unit is connected with a grouting pipe, the front end of the connecting unit is connected with an inner sliding sleeve pipe, the front end of the inner sliding sleeve pipe is closed, the rear end of the inner sliding sleeve pipe is open, the rear end of the inner sliding sleeve pipe is sequentially sleeved with a rear packer unit, a grouting unit and a front packer unit from rear to front, and the front end of the front packer unit is further provided with a pressure adjusting unit. The rear packer unit and the front packer unit can be sealed under the pushing of grout entering the inner sliding sleeve pipe, so that a closed grouting space is formed between the borehole wall, the rear packer unit and the front packer unit. The grouting unit is used for filling grouting material into the closed grouting space. The application has the advantages of small grouting consumption, large grouting reconstruction area range and small through-hole operation amount. The method can realize grouting through hole-by-hole sealing under the condition that multiple discontinuous grouting points exist in the borehole.

Description

Technical Field

[0001] This invention relates to the field of borehole grouting technology, specifically to a pressure-adjustable bidirectional sealing grouting device and method. Background Technology

[0002] Constructing gas extraction and water drainage channels within the coal and rock mass of underground coal mines using drilling methods is an important means of controlling mine gas disasters, preventing water hazards to the roof and floor, and exploring hidden geological factors that could cause disasters. However, when drilling encounters fault fracture zones and water-conducting fissures, it often faces prominent problems such as localized borehole wall collapse and water inrush, leading to drill bit jamming and difficulties in drilling. Furthermore, after drilling, the poor stability of the borehole wall in some sections poses a high risk of collapse and blockage.

[0003] To ensure safe drilling and efficient utilization of boreholes, grouting is the most common method for reinforcing the borehole walls in fractured, collapsed, or water-prone sections. Currently, commonly used grouting methods in coal mines include full-hole grouting and segmented grouting. Full-hole grouting involves directly injecting grout into the borehole from the borehole opening after drilling to the designed depth, using a flange at the borehole opening to stop the grout flow. While the grouting process is simple, its drawbacks include poor reinforcement of deep borehole sections and the need for through-hole drilling after grouting, resulting in a large workload. Segmented grouting includes two types: forward segmented grouting and backward segmented grouting. The former involves retracting the drill bit after drilling to a certain length and encountering abnormalities such as borehole wall collapse or water inrush, installing a grout-stopping flange at the borehole opening, and then injecting grout into the borehole through the borehole opening pipe for reinforcement. After the grout has solidified and the borehole has been penetrated, drilling continues. If borehole collapse or water inrush occurs again, the above operation is repeated. Because this method requires cyclic grouting, waiting for curing, and through-hole operation, the procedure is cumbersome, the grout consumption is large, and the construction period is long. It is mostly used for regional grouting reinforcement projects of the water-resistant layer of the coal seam roof and floor. The segmented retreat grouting method involves stopping the grouting in the hole after drilling to the design depth. The grout stop plug is expanded by compressed air or water to seal the grouting section. After grouting one section, the next section is grouted. Compared with the segmented forward grouting method, it can reduce the amount of through-hole work. This method uses unidirectional grouting and must grout in sections from the bottom of the hole to the hole opening, which cannot achieve fixed-point grouting of local sections of the borehole. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a pressure-adjustable bidirectional sealing grouting device and method. This method uses an expansion-type sealing device to form a sealed space in the grouting hole section through bidirectional grouting, thereby achieving reliable grouting reinforcement of the borehole wall in any section. This solves the problems of complex procedures, time-consuming and labor-intensive processes, and poor results in underground grouting in coal mines in the existing technology.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A pressure-adjustable bidirectional sealing grouting device includes a connecting unit, the rear end of which is connected to a grout delivery pipe, and the front end of which is connected to an inner sliding sleeve. The front end of the inner sliding sleeve is closed and the rear end is open. A rear sealing unit, a grouting unit, and a front sealing unit are sequentially fitted outside the inner sliding sleeve from back to front. A pressure regulating unit is also provided at the front end of the front sealing unit.

[0007] Both the rear sealing unit and the front sealing unit can be set and sealed by the slurry entering the inner sliding sleeve, thereby forming a closed grouting space between the borehole wall, the rear sealing unit and the front sealing unit;

[0008] The grouting unit is used to fill the sealed grouting space with grouting material.

[0009] The present invention also has the following technical features:

[0010] Specifically, the rear sealing unit includes a first rubber core tube and a first rubber cylinder that can expand under the pressure of slurry. The first rubber cylinder is sleeved on the outer wall of the first rubber core tube, and a first grouting hole is opened on the wall of the first rubber core tube where the first rubber cylinder is located.

[0011] The grouting unit includes a grouting pipe, and a second grouting hole is provided on the pipe wall of the grouting pipe;

[0012] The front sealing unit includes a second rubber core tube and a second rubber cylinder that can expand under the pressure of slurry. The second rubber cylinder is sleeved on the outer wall of the second rubber core tube, and a third grouting hole is opened on the wall of the second rubber core tube where the second rubber cylinder is located.

[0013] Furthermore, the pressure regulating unit includes a spring sleeve with a through hole, the front end of the spring sleeve extending into the plug, the front end of the plug being closed, a screw-on sleeve and a spring being disposed in the through hole, the front end face of the screw-on sleeve being connected to the spring, the rear end face of the screw-on sleeve being able to abut against the inner sliding sleeve tube, and the spring being able to extend and retract along the spring sleeve axially under the action of the inner sliding sleeve tube.

[0014] Furthermore, the connecting unit includes a positive and negative connector and a limiting connector connected together, and the rear end of the inner sliding sleeve and the rear end of the first rubber core tube both extend into the limiting connector.

[0015] Furthermore, the inner sliding sleeve has a fourth grouting hole, a fifth grouting hole, and a sixth grouting hole arranged sequentially from back to front on its wall; a first retaining ring is fitted on the outer wall of the inner sliding sleeve on both sides of the fourth grouting hole, and the top surface of the first retaining ring is in contact with the inner wall of the first rubber core tube; a second retaining ring is fitted on the outer wall of the inner sliding sleeve on both sides of the fifth grouting hole, and the top surface of the second retaining ring is in contact with the inner wall of the grouting pipe; a third retaining ring is fitted on the outer wall of the inner sliding sleeve on both sides of the sixth grouting hole, and the top surface of the third retaining ring is in contact with the inner wall of the second rubber core tube.

[0016] Furthermore, a limiting ring is provided at the front end of the inner sliding sleeve near the pressure regulating unit. The limiting ring can abut against the limiting shoulder provided at the rear end of the plug to achieve axial limiting of the inner sliding sleeve.

[0017] Furthermore, the distance a1 between the central axis of the fourth grouting hole and the central axis of the first grouting hole is equal to the distance a2 between the central axis of the sixth grouting hole and the central axis of the third grouting hole, and both a1 and a2 are less than the distance a3 between the central axis of the fifth grouting hole and the central axis of the second grouting hole.

[0018] A pressure-adjustable bidirectional sealing grouting method, implemented using the aforementioned pressure-adjustable bidirectional sealing grouting device, includes the following steps:

[0019] Step 1: Determine the grouting pressure of the grouting unit based on the formation fracture development and formation pressure data obtained from previous explorations;

[0020] Step 2: Determine the initial compression and elastic coefficient of the spring based on the grouting pressure of the determined grouting unit;

[0021] Step 3: Select a spring based on the determined initial compression and spring constant, then install the selected spring into the spring sleeve and tighten the sleeve.

[0022] Step 4: Use the grout delivery pipe to send the grouting device into the hole, so that the front sealing unit and the rear sealing unit are located on both sides of the hole section to be grouted; use the grouting pump to inject grout into the grouting device. The grout enters the inner sliding sleeve through the grout delivery pipe. The inner sliding sleeve moves forward under the action of grout pressure, pushing the plug to move forward along the axis and compressing the spring.

[0023] Step 5: Continue grouting to seal the gap between the rear sealing unit and the borehole wall, as well as the gap between the front sealing unit and the borehole wall;

[0024] Step 6: After the rear sealing unit and the front sealing unit are set, the inner sliding sleeve continues to move forward under the push of the grout, compressing the spring until the sixth grouting hole is aligned with the third grouting hole to form a grouting channel. The grout enters the section to be grouted through the grouting channel to complete the grouting of the section to be grouted.

[0025] Step 7: After the grout pressure reaches the set value, stop grouting. The inner sliding sleeve is reset under the pressure of the spring, and the grouting channel is closed. After the grout solidifies, rotate the grout delivery pipe to disengage the reverse joint from the limit joint and pull out the grout delivery pipe.

[0026] Specifically, the initial compression and elasticity coefficient are determined by the following set of equations:

[0027]

[0028] In the formula,

[0029] P1 is the set sealing pressure, in MPa;

[0030] P2 is the set grouting pressure, in MPa;

[0031] L1 is the axial distance between the fourth grouting hole and the first grouting hole, in mm;

[0032] L2 is the axial distance between the fifth grouting hole and the second grouting hole, in mm;

[0033] r is the radius of the inner cavity of the inner sliding sleeve, in mm;

[0034] Δl is the initial compression of the spring, in mm;

[0035] k is the spring constant, with units of N / mm.

[0036] Furthermore, the specific method for sealing the gap between the rear sealing unit and the borehole wall, and the gap between the front sealing unit and the borehole wall in step 4 is as follows: grout is introduced, and the grout enters the first rubber cylinder through the fourth grouting hole and the first grouting hole, and enters the second rubber cylinder through the sixth grouting hole and the third grouting hole, squeezing the first and second rubber cylinders to expand until the outer walls of the first and second rubber cylinders are in close contact with the borehole wall to achieve a seal.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) The device of the present invention realizes bidirectional sealing grouting of any section of hole to be grouted in the hole by setting a rear sealing unit and a front sealing unit on both sides of the grouting unit, and can realize bidirectional grout stop in the hole after grouting is completed, preventing grout leakage and improving the grouting reinforcement effect.

[0039] (2) Compared with traditional full-hole grouting and segmented grouting, the present invention uses less grout for grouting the section to be grouted, has a larger grouting modification area, and requires less through-hole operation.

[0040] (3) The method of the present invention can ensure the grouting pressure of each grouting point by sealing and grouting each hole segment when there are multiple discontinuous grouting points in the borehole, thus eliminating the problem of poor grouting effect caused by the difference in the degree of fracture development in conventional grouting methods.

[0041] (4) The method of the present invention can adjust the grouting pressure to meet the grouting needs of fractured strata with different formation pressures. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the pressure-adjustable bidirectional sealing grouting device of the present invention.

[0043] Figure 2 This is a schematic diagram of the inner sliding sleeve structure of the present invention;

[0044] Figure 3 This is a schematic diagram of bidirectional sealing grouting in the borehole in Example 2.

[0045] The labels in the diagram represent:

[0046] 1-Inner sliding sleeve, 2-Connecting unit, 3-Rear sealing unit, 4-Grouting unit, 5-Front sealing unit, 6-Pressure regulating unit, 7-Grouting pipe;

[0047] 11-Fourth grouting hole, 12-Fifth grouting hole, 13-Sixth grouting hole, 14-First retaining ring, 15-Second retaining ring, 16-Third retaining ring, 17-Limiting retaining ring;

[0048] 21-Reversible connector, 22-Limit connector;

[0049] 31-First rubber core tube; 32-First rubber tube; 311-First grouting hole;

[0050] 41-Grouting pipe, 42-Second grouting hole;

[0051] 51-Second rubber core tube, 52-Second rubber tube, 511-Third grouting hole;

[0052] 61-Spring sleeve, 62-Plug, 63-Screw-in sleeve, 64-Spring.

[0053] The specific content of the present invention will be further explained in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0054] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0055] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "left," and "right" are generally defined based on the plane of the corresponding figure, while "inner" and "outer" are defined based on the outline of the corresponding figure.

[0056] Example 1

[0057] This embodiment discloses a pressure-adjustable bidirectional sealing grouting device, such as... Figure 1 As shown, it includes a connecting unit 2, the rear end of the connecting unit 2 is connected to the grout delivery pipe 7, the front end of the connecting unit 2 is connected to the inner sliding sleeve 1, the front end of the inner sliding sleeve 1 is closed and the rear end is open, and the inner sliding sleeve 1 is sequentially fitted from back to front with a rear sealing unit 3, a grouting unit 4 and a front sealing unit 5, and the front end of the front sealing unit 5 is also provided with a pressure regulating unit 6.

[0058] Both the rear sealing unit 3 and the front sealing unit 5 can be set and sealed by the slurry entering the inner sliding sleeve 1, thereby forming a closed grouting space between the outer wall of the grouting device, the borehole wall, the rear sealing unit 3 and the front sealing unit 5.

[0059] Grouting unit 4 is used to fill the sealed grouting space with grouting material.

[0060] As a preferred embodiment, the rear sealing unit 3 includes a first rubber core tube 31 and a first rubber cylinder 32 that can expand under the pressure of slurry. The first rubber cylinder 32 is sleeved on the outer wall of the first rubber core tube 31. A first grouting hole 311 is opened on the tube wall of the first rubber core tube 31 where the first rubber cylinder 32 is located. The slurry can enter the space between the first rubber core tube 31 and the first rubber cylinder 32 through the first grouting hole 311, causing the first rubber cylinder 32 to expand.

[0061] Grouting unit 4 includes grouting pipe 41, and a second grouting hole 42 is provided on the pipe wall of grouting pipe 41;

[0062] The front sealing unit 5 includes a second rubber core tube 51 and a second rubber cylinder 52 that can expand under the pressure of slurry. The second rubber cylinder 52 is sleeved on the outer wall of the second rubber core tube 51. A third grouting hole 511 is opened on the tube wall of the second rubber core tube 51 where the second rubber cylinder 52 is located. The slurry can enter the space between the second rubber core tube 51 and the second rubber cylinder 52 through the third grouting hole 511, causing the second rubber cylinder 52 to expand.

[0063] Specifically: the two ends of the grouting pipe 41 are respectively connected to the first rubber core tube 31 and the second rubber core tube 51, and the first rubber core tube 31, the grouting pipe 41 and the second rubber core tube 51 can be sealed and inserted together.

[0064] In this embodiment, both the first rubber tube 32 and the second rubber tube 52 are made of expandable material and respectively cover the first rubber tube core tube 31 and the second rubber tube core tube 51. The two ends of the rubber tube are fastened with a pressure ring, which has the characteristics of easy modular assembly and simple structure. The two ends of the grouting pipe 41 are respectively provided with a grouting pipe front connector and a grouting pipe rear connector. Both the grouting pipe front connector and the grouting pipe rear connector are provided with internal threads, which are threaded to the first rubber tube core tube 31 and the second rubber tube core tube 51 respectively by means of the internal threads.

[0065] As a preferred embodiment, the pressure regulating unit 6 includes a spring sleeve 61 with a through hole. The front end of the spring sleeve 61 extends into the plug 62, and the front end of the plug 62 is closed. A screw-on sleeve 63 and a spring 64 are provided in the through hole. The front end face of the screw-on sleeve 63 is connected to the spring 64, and the rear end face of the screw-on sleeve 63 can abut against the inner sliding sleeve 1. The spring 64 can extend and retract along the spring sleeve 61 axially under the action of the slurry entering the inner sliding sleeve 1.

[0066] The diameter of the engagement sleeve 63 is greater than the diameter of the inner sliding sleeve 1 and smaller than the diameter of the through hole. The diameter of the inner sliding sleeve 1 is less than or equal to the diameter of the through hole. That is, the inner sliding sleeve 1 can extend into the through hole and push the engagement sleeve 63 and the spring 64.

[0067] In a preferred embodiment, the connecting unit 2 includes a reversible connector 21 and a limiting connector 22, both of which are hollow and connected by reverse threads. The reversible connector 21 has a positive thread and a negative thread with opposite threads at both ends, connected to the grouting pipe 7 via the positive thread and to the limiting connector 2 via the negative thread. The limiting connector 2 has a negative internal thread at its rear end for connecting to the negative positive thread on the reversible connector 1, and a positive internal thread at its front end for connecting to the first rubber core tube 31.

[0068] The limiting joint 22 is provided with a first limiting step surface for limiting the first rubber core tube 31 and a second limiting step surface for limiting the inner sliding sleeve tube 1.

[0069] The rear end of the inner sliding sleeve 1 extends into the limiting joint 22 and is limited by the limiting step surface. The connecting joint and the inner sliding sleeve 1 form a grout delivery channel in the grouting device. The grout delivered from the grout delivery pipe 7 is sent into the sliding core tube through the connecting joint.

[0070] In a preferred embodiment, the inner sliding sleeve 1 has a fourth grouting hole 11, a fifth grouting hole 12, and a sixth grouting hole 13 arranged sequentially from back to front on its wall. A first retaining ring 14 is fitted on the outer wall of the inner sliding sleeve 1 on both sides of the fourth grouting hole 11, and the top surface of the first retaining ring 14 is in contact with the inner wall of the first rubber core tube 31. A second retaining ring 15 is fitted on the outer wall of the inner sliding sleeve 1 on both sides of the fifth grouting hole 12, and the top surface of the second retaining ring 15 is in contact with the inner wall of the grouting pipe 41. A third retaining ring 16 is fitted on the outer wall of the inner sliding sleeve 1 on both sides of the sixth grouting hole 13, and the top surface of the third retaining ring 16 is in contact with the inner wall of the second rubber core tube 51.

[0071] A limit ring 17 is also provided at the front end of the inner sliding sleeve 1 near the pressure regulating unit 6. The limit ring 17 can abut against the limit shoulder provided at the rear end of the plug 62 to achieve axial limit of the inner sliding sleeve 1.

[0072] There are multiple first grouting holes 311, second grouting holes 42, third grouting holes 511, fourth grouting holes 11, fifth grouting holes 12, and sixth grouting holes 13. Multiple first grouting holes 311 are arranged circumferentially along the first rubber sleeve core tube 31; multiple second grouting holes 42 are arranged circumferentially along the grouting pipe 41; and multiple third grouting holes 511 are arranged circumferentially along the second rubber sleeve core tube 51.

[0073] Furthermore, multiple fourth grouting holes 11, fifth grouting holes 12 and sixth grouting holes 13 are arranged along the circumference of the inner sliding sleeve 1.

[0074] The first retaining ring 14 is used to prevent grout from entering the gap between the inner sliding sleeve 1 and the first rubber core tube 31; the second retaining ring 15 is used to prevent grout from entering the gap between the inner sliding sleeve 1 and the grouting pipe 41; and the third retaining ring 16 is used to prevent grout from entering the gap between the inner sliding sleeve 1 and the second rubber core tube 51.

[0075] As a preferred embodiment, the distance a1 between the central axis of the fourth grouting hole 11 and the central axis of the first grouting hole 311 is equal to the distance a2 between the central axis of the sixth grouting hole 13 and the central axis of the third grouting hole 511, and both a1 and a2 are less than the distance a3 between the central axis of the fifth grouting hole 12 and the central axis of the second grouting hole 42.

[0076] By setting the above spacings a1, a2, and a3, it can be ensured that when the fourth grouting hole 11 and the first grouting hole 311, and the sixth grouting hole 13 and the third grouting hole 511 are aligned simultaneously under the action of high-pressure grout, the fifth grouting hole 12 and the second grouting hole 42 are staggered. That is, at this time, the grout can only enter the first rubber sleeve 32 and the second rubber sleeve 52 through the connected holes respectively, so as to achieve the setting and sealing of the rear sealing unit 3 and the front sealing unit 5, and will not enter the section to be grouted through the fifth grouting hole 12 and the second grouting hole 42.

[0077] The process of using the device of the present invention is as follows:

[0078] The slurry enters the inner sliding sleeve 1 through the slurry delivery pipe 7 and the connecting unit 2. Under the action of the slurry pressure, the inner sliding sleeve 1 moves forward and pushes the plug 62 to move forward axially to compress the spring 64. When the fourth grouting hole 11 and the sixth grouting hole 13 on the inner sliding sleeve 1 are connected to the first grouting hole 311 and the third grouting hole 511 on the first rubber core tube, respectively, the slurry flows into the first rubber cylinder 32 and the second rubber cylinder 52. During this process, the slurry pressure in the inner sliding sleeve 1 remains stable and is balanced with the compression force of the spring 64 in the pressure regulating unit, and the inner sliding sleeve 1 stops moving forward.

[0079] After the grout fills the first rubber sleeve 32 and the second rubber sleeve 52, as the grouting pump continues to pump in the grout, the grout pressure in the inner cavity of the inner sliding sleeve 1 continues to increase. Under the pressure of the grout, the inner sliding sleeve 1 continues to move forward and pushes the plug 62 forward along the axial direction to compress the spring 64 until the limiting ring 17 on the inner sliding sleeve 1 abuts against the limiting shoulder at the rear end of the plug. At this time, the fifth grouting hole 12 on the inner sliding sleeve 1 is connected to the second grouting hole 42 on the grouting pipe 41, and the grout enters the section to be grouted.

[0080] Example 2

[0081] This embodiment discloses a pressure-adjustable bidirectional sealing grouting method, which is implemented using the pressure-adjustable bidirectional sealing grouting device disclosed in Embodiment 1, and specifically includes the following steps:

[0082] Step 1: Based on the formation pressure data obtained from the previous exploration, determine the sealing pressure and grouting pressure of the pressure-adjustable bidirectional sealing grouting device;

[0083] Step 2: Determine the initial compression and elastic coefficient of spring 64 based on the determined sealing pressure and grouting pressure;

[0084] The initial compression and elasticity coefficient are determined by the following set of equations:

[0085]

[0086] In the formula,

[0087] P1 is the set sealing pressure, in MPa;

[0088] P2 is the set grouting pressure, in MPa;

[0089] L1 is the axial distance between the fourth grouting hole and the first grouting hole, in mm;

[0090] L2 is the axial distance between the fifth grouting hole and the second grouting hole, in mm;

[0091] r is the radius of the inner cavity of the inner sliding sleeve, in mm;

[0092] Δl is the initial compression of the spring, in mm;

[0093] k is the spring constant, with units of N / mm.

[0094] Step 3: Select spring 64 according to the determined initial compression and spring constant, then install the selected spring 64 in spring sleeve 61 and tighten the engagement sleeve 63.

[0095] Step 4: Use the grouting pipe 7 to send the grouting device into the hole, so that the front sealing unit 5 and the rear sealing unit 3 are located on both sides of the section of hole to be grouted; use the grouting pump to inject high-pressure grout into the grouting device. The grout enters the inner sliding sleeve 1 through the grouting pipe 7. The inner sliding sleeve 1 moves forward under the action of grout pressure, which in turn pushes the plug 62 to move forward along the axial direction to compress the spring 64. The multiple grouting holes opened on the inner sliding sleeve 1 also move forward accordingly.

[0096] Cement slurry is used in this embodiment.

[0097] Step 5: Seal the gap between the rear sealing unit 3 and the borehole wall, and the gap between the front sealing unit 5 and the borehole wall.

[0098] The specific method is as follows: Grout is introduced, and the inner sliding sleeve 1 moves forward under the pressure of the grout. The fourth grouting hole 11 and the sixth grouting hole 13 are connected to the first grouting hole 311 and the third grouting hole 511, respectively. The grout enters the first rubber sleeve 32 through the fourth grouting hole 11 and the first grouting hole 311, and enters the second rubber sleeve 52 through the sixth grouting hole 13 and the third grouting hole 511, compressing the first rubber sleeve 32 and the second rubber sleeve 52 to expand until the outer walls of the first rubber sleeve 32 and the second rubber sleeve 52 are in close contact with the borehole wall to achieve a seal. During this process, the grout pressure in the inner cavity of the inner sliding sleeve 1 remains stable and balances with the compression force of the compression spring 64, at which point the inner sliding sleeve 1 stops moving forward.

[0099] Step 6: After the rear sealing unit 3 and the front sealing unit 5 are set, the inner sliding sleeve 1 continues to move forward under the push of the grout, compressing the spring 64, until the sixth grouting hole 13 and the third grouting hole 511 are aligned to form a grouting channel. At this time, the fourth grouting hole 11 and the first grouting hole 311, and the sixth grouting hole 13 and the third grouting hole 511 are staggered. The grout enters the section to be grouted through the grouting channel formed by the fifth grouting hole 12 and the second grouting hole 42, completing the grouting of the section to be grouted.

[0100] After the grout enters the section to be grouted and the formation fractures, the grouting pressure can be maintained at the preset pressure value. If the grouting pressure continues to increase, the grout will be squeezed into the fractures of the hole wall of the section to be grouted under the sealing and pressure-maintaining effect of the rear sealing unit 3 and the front sealing unit 5.

[0101] Step 7: After the grout pressure reaches the set value, stop grouting. The inner sliding sleeve 1 is reset under the pressure of the spring 64, and the grouting channel is closed. After the grout in the rear sealing unit 3 and the front sealing unit 5 solidifies, rotate the grout delivery pipe 7 to disengage the positive and negative connectors 21 and the limiting connectors 22, pull out the grout delivery pipe 7, place the grouting device in the hole, and wait for the grout in the grouting hole section to solidify.

[0102] When there are multiple sections of borehole that need reinforcement and require grouting, repeat the above steps to reinforce each section from deep to shallow.

[0103] After the grouting operation is completed, a milling drill can be lowered to break the first rubber sleeve 32 and the second rubber sleeve 52, and drill out the remaining parts of the grouting unit. The remaining parts can be reused after cleaning.

[0104] In summary, the method of this invention can ensure the grouting pressure at each grouting point by sealing and grouting each section of the borehole when there are multiple discontinuous grouting points within the borehole, thus eliminating the problem of poor grouting effect caused by differences in the degree of fracture development in conventional grouting methods.

[0105] As can be seen, the device and method of this invention enable real-time measurement of gas parameters at predetermined locations during directional long borehole construction, and allow for calculation and analysis of coal seam gas occurrence based on parameter changes. This not only provides timeliness but also ensures the accuracy and reliability of the measurement data. Furthermore, it avoids complex procedures such as drilling and hoisting, reducing the difficulty of implementation.

[0106] In the above description, unless otherwise explicitly specified and limited, terms such as "setup" and "connection" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections, etc. Those skilled in the art can understand the specific meaning of the above terms in this technical solution according to the specific circumstances.

[0107] The specific technical features described in the above embodiments can be combined in any suitable manner without contradiction, as long as they do not violate the spirit of the present invention, and should also be regarded as the content disclosed by the present invention.

Claims

1. A pressure-adjustable bidirectional sealing grouting device, comprising a connecting unit (2), wherein the rear end of the connecting unit (2) is connected to a grout delivery pipe (7), characterized in that, The front end of the connecting unit (2) is connected to an inner sliding sleeve (1) that is closed at the front end and open at the rear end. The inner sliding sleeve (1) is fitted with a rear sealing unit (3), a grouting unit (4) and a front sealing unit (5) in sequence from back to front. The front end of the front sealing unit (5) is also provided with a pressure regulating unit (6). Both the rear sealing unit (3) and the front sealing unit (5) can be set and sealed by the slurry entering the inner sliding sleeve (1), thereby forming a closed grouting space between the borehole wall, the rear sealing unit (3) and the front sealing unit (5); The grouting unit (4) is used to fill the sealed grouting space with grouting material; The rear sealing unit (3) includes a first rubber core tube (31) and a first rubber cylinder (32) that can expand under the pressure of slurry. A first grouting hole (311) is provided on the wall of the first rubber core tube (31) at the location of the first rubber cylinder (32). The grouting unit (4) includes a grouting pipe (41), and a second grouting hole (42) is provided on the pipe wall of the grouting pipe (41). The front sealing unit (5) includes a second rubber core tube (51) and a second rubber tube (52) that can expand under the pressure of slurry. A third grouting hole (511) is provided on the wall of the second rubber core tube (51) at the location of the second rubber tube (52). The inner sliding sleeve (1) has a fourth grouting hole (11), a fifth grouting hole (12) and a sixth grouting hole (13) arranged sequentially from back to front on the pipe wall. The distance a1 between the central axis of the fourth grouting hole (11) and the central axis of the first grouting hole (311) is equal to the distance a2 between the central axis of the sixth grouting hole (13) and the central axis of the third grouting hole (511), and both a1 and a2 are less than the distance a3 between the central axis of the fifth grouting hole (12) and the central axis of the second grouting hole (42).

2. The pressure-adjustable bidirectional sealing grouting device as described in claim 1, characterized in that, The first rubber tube (32) is sleeved on the outer wall of the first rubber tube core tube (31), and the second rubber tube (52) is sleeved on the outer wall of the second rubber tube core tube (51).

3. The pressure-adjustable bidirectional sealing grouting device as described in claim 1, characterized in that, The pressure regulating unit (6) includes a spring sleeve (61) with a through hole. The front end of the spring sleeve (61) extends into the plug (62), and the front end of the plug (62) is closed. A screw-on sleeve (63) and a spring (64) are provided in the through hole. The front end face of the screw-on sleeve (63) is connected to the spring (64), and the rear end face of the screw-on sleeve (63) can abut against the inner sliding sleeve (1). The spring (64) can extend and retract along the spring sleeve (61) axially under the action of the inner sliding sleeve (1).

4. The pressure-adjustable bidirectional sealing grouting device as described in claim 1, characterized in that, The connecting unit (2) includes a positive and negative connector (21) and a limiting connector (22) for connection. The rear end of the inner sliding sleeve (1) and the rear end of the first rubber core tube (31) both extend into the limiting connector (22).

5. The pressure-adjustable bidirectional sealing grouting device as described in claim 2, characterized in that, A first retaining ring (14) is fitted on the outer wall of the inner sliding sleeve (1) on both sides of the fourth grouting hole (11), and the top surface of the first retaining ring (14) is in contact with the inner wall of the first rubber core tube (31); a second retaining ring (15) is fitted on the outer wall of the inner sliding sleeve (1) on both sides of the fifth grouting hole (12), and the top surface of the second retaining ring (15) is in contact with the inner wall of the grouting pipe (41); a third retaining ring (16) is fitted on the outer wall of the inner sliding sleeve (1) on both sides of the sixth grouting hole (13), and the top surface of the third retaining ring (16) is in contact with the inner wall of the second rubber core tube (51).

6. The pressure-adjustable bidirectional sealing grouting device as described in claim 3, characterized in that, A limiting ring (17) is also provided at the front end of the inner sliding sleeve (1) near the pressure regulating unit (6). The limiting ring (17) can abut against the limiting shoulder provided at the rear end of the plug (62) to achieve axial limiting of the inner sliding sleeve (1).

7. A pressure-adjustable bidirectional sealing grouting method, characterized in that, The method is implemented using the pressure-adjustable bidirectional sealing grouting device according to any one of claims 1 to 6, and specifically includes the following steps: Step 1: Based on the formation fracture development and formation pressure data obtained from previous exploration, determine the sealing pressure and grouting pressure of the pressure-adjustable bidirectional sealing grouting device. Step 2: Determine the initial compression and elastic coefficient of the spring (64) based on the determined sealing pressure and grouting pressure; Step 3: Select a spring (64) based on the determined initial compression and spring constant, and then install the selected spring (64) into the spring sleeve (61) and tighten the engagement sleeve (63). Step 4: Use the grouting pipe (7) to send the grouting device into the hole, so that the front sealing unit (5) and the rear sealing unit (3) are located on both sides of the hole section to be grouted; use the grouting pump to inject grout into the grouting device, and the grout enters the inner sliding sleeve (1) through the grouting pipe (7). The inner sliding sleeve (1) moves forward under the action of grout pressure, pushing the plug (62) to move forward along the axial direction to compress the spring (64). Step 5: Continue grouting to relieve pressure inside the drill bit and seal the gap between the rear sealing unit (3) and the borehole wall, as well as the gap between the front sealing unit (5) and the borehole wall. Step 6: After the rear sealing unit (3) and the front sealing unit (5) are set, the inner sliding sleeve (1) continues to compress the spring (64) and move forward under the push of the grout until the sixth grouting hole (13) is aligned with the third grouting hole (511) to form a grouting channel. The grout enters the section to be grouted through the grouting channel to complete the grouting of the section to be grouted. Step 7: After the grout pressure reaches the set value, stop grouting. The inner sliding sleeve (1) is reset under the pressure of the spring (64), and the grouting channel is closed. After the grout solidifies, rotate the grout delivery pipe (7) to disengage the reverse joint from the limit joint and pull out the grout delivery pipe (7).

8. The pressure-adjustable bidirectional sealing grouting method as described in claim 7, characterized in that, The initial compression and elasticity coefficient are determined by the following set of equations: In the formula, The set sealing pressure, in MPa; P 2 represents the set grouting pressure, in MPa; This represents the axial distance between the fourth grouting hole and the first grouting hole, in mm. This represents the axial distance between the fifth grouting hole and the second grouting hole, in mm. The radius of the inner cavity of the inner sliding sleeve is in mm. This represents the initial compression of the spring, in mm. is the spring constant, expressed in N / mm.

9. The pressure-adjustable bidirectional sealing grouting method as described in claim 7, characterized in that, The specific method for sealing the gap between the rear sealing unit (3) and the borehole wall, and the gap between the front sealing unit (5) and the borehole wall in step 4 is as follows: grout is introduced, and the grout enters the first rubber cylinder (32) through the fourth grouting hole (11) and the first grouting hole (311), and enters the second rubber cylinder (52) through the sixth grouting hole (13) and the third grouting hole (511). The first rubber cylinder (32) and the second rubber cylinder (52) are squeezed to expand until the outer walls of the first rubber cylinder (32) and the second rubber cylinder (52) are in close contact with the borehole wall to achieve a seal.

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