Retrusive segmented sleeve valve pipe grouting process for karst treatment

Abstract

The invention discloses a retreating type segmented sleeve valve pipe grouting process for karst treatment, and belongs to the technical field of karst stratum reinforcement. The process comprises the steps of drilling construction, device arrangement, grouting positioning, segmented grouting, retreating type displacement grouting and ending treatment, and is characterized in that a grouting core pipe adopts a sealing telescopic connecting structure of an inner core pipe and an outer sleeve, and is matched with a telescopic driving piece, an elastic connecting piece and a first pressure sensor; dynamic adjustment of the size of a grouting space and real-time monitoring of pressure are achieved, and the risk of excessive or insufficient grouting is avoided in an intermittent grouting mode; the vent pipe and the one-way valve are staggered, pressure in the pipe is balanced, the one-way valve is assisted to rapidly retract, and backflow and slurry mixing are avoided; and the optional rotating device and the stirring piece cooperate to prevent slurry deposition, so that the grouting uniformity is improved. The grouting precision and controllability are remarkably improved, safety and stability of construction are comprehensively guaranteed, the grouting filling compactness and long-term stability are optimized, and the method is suitable for layering of karst caves in different forms.

Description

Technical Field

[0001] This invention relates to the field of karst formation reinforcement technology, and in particular to a retreating segmented sleeve valve grouting process for karst treatment. Background Technology

[0002] In engineering construction in karst areas, adverse geological conditions such as karst caves and fractured zones can easily lead to insufficient bearing capacity and poor stability of the strata, posing safety hazards to subsequent construction (such as shield tunneling and bridge foundation construction). Therefore, it is necessary to reinforce the karst strata through sleeve valve grouting technology.

[0003] While the existing backward segmented sleeve valve grouting process can achieve layered grouting, it still has many technical defects in practical applications: First, the grouting accuracy and controllability are insufficient. The sealing plug spacing of the traditional grouting core tube is fixed, which cannot be adapted to the layering of karst caves of different shapes and thicknesses. Moreover, the grouting volume largely depends on construction experience for control, which can easily lead to over-grouting or under-grouting. Over-grouting will cause the pressure inside the karst cave and grouting casing to exceed the standard, leading to risks such as casing cracking, one-way valve damage, and grout backflow blockage, and in severe cases, borehole collapse. Under-grouting will fail to meet the bearing capacity requirements of the stratum reinforcement, affecting the quality of the project.

[0004] Secondly, the construction safety and stability are not good. During the up and down movement of the grouting core pipe, negative pressure or overpressure is easily formed inside the pipe, which leads to deformation of the grouting sleeve and failure of the sealing structure. At the same time, the one-way valve after grouting is prone to not closing in time due to the viscosity of the grout, which can cause grout backflow, cross-contamination and intrusion of stratum mud and sand into the grouting pipe, further aggravating the construction risks and affecting the continuity of segmented grouting.

[0005] Third, the grouting effect and long-term stability are difficult to guarantee. Under the traditional single-injection grouting mode, the grout is prone to uneven concentration due to gravity deposition, with the bottom being too thick and the top too thin. Moreover, the shrinkage cracks generated during the solidification process of the grout cannot be effectively filled, resulting in insufficient compaction of the karst cave filling. In addition, the deposited grout may also block the grouting port, causing subsequent grouting to be interrupted, affecting the uniformity of reinforcement and the long-term stability of the strata, making it difficult to meet the high-standard reinforcement requirements of complex karst strata. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of insufficient grouting accuracy and controllability, poor construction safety and stability, and difficulty in guaranteeing grouting effect and long-term stability in the existing technology of backward segmented sleeve valve grouting. Therefore, this invention proposes a backward segmented sleeve valve grouting process for karst treatment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A retreating segmented sleeve valve grouting process for karst treatment includes the following steps: S1. Drilling construction: The positioning instrument is used to mark the drilling position, and the hole position error is ≤10cm; before drilling, the pipelines and obstacles are checked to a depth of 3-6m. The drilling rig is positioned and drilling begins, and the vertical deviation rate of the drilling hole is <1%. After drilling through special geological conditions, the parameters of the karst cave are recorded. After acceptance, the pipe is prepared for installation. S2. Equipment Layout: The grouting casing is lowered into the borehole, and the bottom is sealed by the bottom cover. The space between the casing and the borehole wall is filled with casing material, and the grouting material is injected 1-2m below the ground. Grouting ports with one-way valves are set at different heights of the grouting casing. After the grouting core tube is inserted, the grouting space is formed by the upper and lower annular sealing plugs. The grouting core tube wall is provided with corresponding grouting channels. The bottom cover is fixed with a vent pipe, and the top of the grouting core tube is connected to the grouting equipment and lifting device. S3, Grouting Positioning: The lifting device drives the grouting core tube to be positioned to the lowest grouting section. The pressure is balanced through the vent pipe during movement. S4. Segmented grouting: Grout is injected into the grouting space through the grouting channel, opens the one-way valve and seeps into the formation, the vent pipe continuously balances the pressure, and stabilizes the pressure for a preset time after reaching the standard. S5, Reverse grouting: Pull the grouting core pipe to the previous grouting section, and repeat S3~S4 to achieve segmented grouting from bottom to top; S6. Finishing treatment: Flush the pipeline and pull out the grouting core pipe. Pour cement grout into the grouting sleeve and smooth the hole after it solidifies. The grouting core tube includes an inner core tube and an outer tube, which are sealed and telescopically connected and equipped with a telescopic drive component. The telescopic end of the telescopic drive component is connected to the outer tube via an elastic connector and has a built-in locking component. A first pressure sensor is installed at the elastic connector. Grouting is carried out in an intermittent manner. The pressure is detected by the first pressure sensor. When the pressure reaches the standard, the locking component is unlocked to increase the grouting space. After stabilization, the locking component is relocked and grouting is repeated.

[0008] In some embodiments, a control valve is detachably installed at the end of the vent pipe located above the grouting sleeve, and a gas supply pipe is selectively connected to the top of the vent pipe; during grouting, if the grouting pressure is insufficient, pressurized gas is supplied to the vent pipe through the gas supply pipe; if there is a risk of excessive grout, the control valve is opened to use negative pressure to discharge the gas and excess grout in the space in the reverse direction.

[0009] In some embodiments, the inner core tube is provided with a rotating device at the top, and the rotating device is rotatably engaged with the connecting pipe of the grouting equipment. The rotating device is used to drive the inner core tube to rotate synchronously with the outer sleeve. During the grouting process, the inner core tube is driven to rotate by the rotating device, so that the grout is evenly distributed in the grouting space.

[0010] In some embodiments, a second pressure sensor is provided between the telescopic end of the lifting device and the inner core tube, and a stirring element is provided circumferentially at the bottom of the inner core tube; In step S5, when the inner core tube is pulled up, the second pressure sensor detects the pulling pressure value: if the pulling force value is within the preset threshold range, the rotating device is selectively activated to drive the inner core tube and the stirring component to rotate, and the lifting device is used to pull up the inner core tube. If the tension value exceeds the preset threshold, the back suction function of the grouting equipment is activated to reduce the weight of grout and residue in the grouting space. Then, the lifting and rotating devices are activated to drive the agitator to disturb the sediment layer and lift the inner core tube.

[0011] In some embodiments, the one-way valve is a rubber sleeve one-way valve. When the grouting space increases, a negative pressure is formed inside, which helps the rubber sleeve one-way valve to retract and block the grouting port.

[0012] In some embodiments, the telescopic drive is a hydraulic cylinder, the elastic connector is a spring, and the locking element is an electromagnetic pin, which is located inside the spring and normally remains in an extended locked state.

[0013] In some embodiments, in step S5, if the length of the grouting core tube pulled out exceeds the length of one section of the tube, the corresponding section of the core tube and the joint are removed, and the construction of the next grouting section continues.

[0014] In some embodiments, in step S6, the cement grout injected into the grouting sleeve has a water-cement ratio of 1:1, and the orifice is smoothed with M15 mortar.

[0015] In some embodiments, the rotating device includes a drive motor, a synchronous belt, and external teeth disposed on the top circumferential direction of the inner core tube. The drive motor drives the external teeth to rotate through the synchronous belt, thereby driving the inner core tube to rotate.

[0016] In some embodiments, a wear-resistant sealing ring is provided at the sealing and expansion joint between the inner core tube and the outer sleeve tube to prevent grout leakage in the grouting space.

[0017] Compared with the prior art, the present invention provides a backward segmented sleeve valve grouting process for karst treatment, which has the following beneficial effects.

[0018] 1. This invention, through the sealing and telescopic structure of the inner core tube and outer sleeve of the grouting core tube, combined with the telescopic drive component, elastic connector and first pressure sensor, realizes dynamic adjustment of the grouting space size and real-time monitoring of the grouting pressure; combined with the intermittent grouting mode, it can accurately avoid the risks of sleeve cracking and one-way valve damage caused by excessive grouting, while avoiding the problem of substandard reinforcement caused by insufficient grouting, adapting to the layering of karst caves of different shapes and thicknesses, and achieving targeted and precise reinforcement.

[0019] 2. This invention, by staggering the arrangement of the vent pipe and the one-way valve, can balance the pressure inside the pipe in real time when the grouting core pipe moves, preventing casing deformation and sealing failure caused by negative or overpressure; the rubber sleeve one-way valve, in conjunction with the negative pressure generated when the grouting space increases, can quickly retract and seal the grouting port, effectively preventing grout backflow, cross-contamination, and intrusion of stratum mud and sand; the optional control valve and gas supply pipeline design can flexibly realize pressurized assisted grouting or negative pressure relief, further reducing construction risks.

[0020] 3. This invention forms a closed loop of grouting-pressure stabilization-negative pressure retraction-re-grouting through intermittent grouting. The preceding grout forms a solidified skeleton, and the subsequent grout fills the shrinkage gaps, reducing grout shrinkage cracks and improving the density and uniformity of karst filling. The synergistic effect of the rotating device and the stirring components can avoid uneven concentration and pipeline blockage caused by grout deposition, ensuring that the grout is tightly bonded to the strata and solidified body, and guaranteeing the bearing capacity and long-term structural stability of the strata after karst treatment.

[0021] Other advantages, objectives and features of the invention will be set forth in part in the description which follows; and in part will be apparent to those skilled in the art upon examination of the following description; or may be learned from practice of the invention. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the drilling structure of the present invention.

[0023] Figure 2 This is a schematic diagram of the grouting sleeve of the present invention.

[0024] Figure 3 This is a schematic diagram of the structure for injecting the casing material according to the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of the grout-stopping material of the present invention.

[0026] Figure 5 For the present invention Figure 4 Enlarged structural diagram of area A in the middle.

[0027] Figure 6 This is a schematic diagram of the structure of the protective cover above the grouting sleeve and inner core tube of the present invention.

[0028] Figure 7 This is a schematic diagram of the structure after sealing the holes in this invention.

[0029] Figure 8 This is a schematic diagram of the telescopic drive component of the present invention.

[0030] Figure 9 For the present invention Figure 8 A magnified structural diagram of region B in the middle.

[0031] Figure 10 For the present invention Figure 8 A magnified structural diagram of region C.

[0032] In the picture: 1. Grouting sleeve; 101. Bottom cover; 102. Vent pipe; 2. Inner core tube; 202. Grouting port; 3. Outer sleeve; 301. Upper annular sealing plug; 302. Lower annular sealing plug; 303. Grouting space; 4. Telescopic drive component; 401. Electromagnetic pin; 402. Spring. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0034] Reference Figures 1 to 7 A retreating segmented sleeve valve grouting process for karst treatment includes the following steps: Step S1: Use a positioning instrument to measure and mark the borehole position, and control the borehole position error within 10cm. Before drilling, use manual excavation (Luoyang shovel excavation, heavy hammer light hammering) combined with an underground pipeline detector to complete the inspection of pipelines and obstacles at a depth of 3-6m. After confirming safety, the drilling rig is positioned and drilling begins. The vertical deviation rate of the borehole is less than 1%. After drilling through special geological features such as karst caves and fracture zones, record the size, depth and stratum parameters of the karst caves. After the supervisor's acceptance, prepare to lay the pipe.

[0035] Step S2: The prefabricated grouting sleeve 1 is vertically lowered into the borehole. The bottom of the grouting sleeve 1 is sealed by the bottom cover 101. The space between the sleeve body and the borehole wall is filled with casing material. Grouting stop material is injected 1-2m below the ground. Grouting ports 202 are opened circumferentially at different horizontal heights on the grouting sleeve 1. A rubber sleeve check valve is installed at the grouting port 202. The grouting core tube equipped with the lower annular sealing plug 302 and the upper annular sealing plug 301 is inserted into the grouting sleeve 1 to ensure that a closed grouting space 303 is formed between the two sealing plugs, and the grouting port 202 on the grouting core tube wall corresponds to this space. The vent pipe 102 (fixed to the bottom inside the bottom cover 101, extending axially along the grouting sleeve 1 and offset from the check valve) is connected to the top of the grouting core tube to the grouting equipment and lifting device. In step S3, the grouting core tube is moved up and down by the lifting device to precisely position the grouting space 303 to the lowest target grouting section. At this time, the grouting core tube moves the lower annular sealing plug 302, and the gas in the space below it interacts with the outside through the vent pipe 102 to balance the pressure inside the tube and prevent the sealing plug from moving, which could cause the tube to deform or the seal to fail. Step S4: Start the grouting equipment. The grout is injected into the grouting space 303 through the grouting core pipe. When the grout pressure reaches the design value, the rubber sleeve check valve is opened, and the grout is evenly seeped into the karst cave and the surrounding soil layer. During the grouting process, the pressure is continuously balanced through the vent pipe 102 to ensure stable diffusion of the grout until the design grouting volume is reached and the pressure is stabilized for 10 minutes.

[0036] Step S5: After completing the grouting of the current section, shut down the grouting equipment and lift the grouting core tube upwards using the lifting device. This will cause the lower annular sealing plug 302 and the upper annular sealing plug 301 to move synchronously to the next grouting section. The vent pipe 102 will balance the internal pressure during the movement process in real time. Repeat steps 3 to 4 to achieve backward segmented grouting from bottom to top. If the length of the core tube pulled out exceeds the length of one pipe section, remove the corresponding section and continue construction.

[0037] Step S6: After all grouting sections are completed, inject clean water into the grouting core pipe to flush the pipeline and prevent grout residue from clogging it. After pulling out the grouting core pipe, pour 1:1 cement grout into the grouting sleeve 1 to the hole opening to ensure that it is filled tightly. After the cement grout has solidified, use M15 mortar to smooth the hole opening and restore the original state of the ground.

[0038] The grouting sleeve 1 has grouting ports 202 at different horizontal heights along its circumference; a rubber sleeve check valve is provided at each grouting port 202; a lower annular sealing plug 302 and an upper annular sealing plug 301 are provided on the outside of the grouting core tube; a grouting space 303 is formed between the lower annular sealing plug 302 and the upper annular sealing plug 301; a grouting port 202 with internal and external communication is provided on the tube wall of the grouting core tube at a position corresponding to the grouting space 303; a lower bottom cover 101 is provided at the bottom of the grouting sleeve 1; and a grouting device is connected to the top of the grouting core tube.

[0039] It also includes a lifting device to control the up and down position of the grouting core tube, enabling segmented grouting from bottom to top.

[0040] There is also a vent pipe 102 to facilitate the permeation of internal and external gases. The vent pipe 102 is fixed to the bottom inside of the lower cover 101, ensuring that it runs through the grouting sleeve 1 axially and is staggered from the rubber sleeve check valve. When the grouting core tube drives the lower annular sealing plug 302 to move up and down, the gas in the space below the grouting core tube and the lower annular sealing plug 302 interacts with the external gas through the vent pipe 102 to balance the pressure.

[0041] In this invention, the grouting sleeve 1 serves as a pre-embedded and fixed grouting channel, and its grouting ports 202 at different horizontal heights, together with the rubber sleeve check valve, form a directional grouting structure. During grouting, the grout forms high pressure within the grouting space 303, opening the rubber sleeve check valve to permeate into the karst cave and stratum. After grouting stops, the rubber sleeve elastically retracts to seal the grouting ports 202, effectively preventing the backflow of stratum sediment and groundwater, avoiding grouting pipe blockage, ensuring the continuity of segmented grouting, and meeting the technical requirements for precise filling and prevention of grout leakage in karst treatment.

[0042] The lower annular sealing plug 302 and the upper annular sealing plug 301 on the outside of the grouting core tube form an independent grouting space 303, and this space corresponds to the grouting port 202 on the core tube wall. During grouting, the sealing plug fits tightly against the inner wall of the grouting sleeve 1, confining the grout within the target grouting section and preventing the grout from flowing up and down along the inner wall of the grouting sleeve 1, thus achieving segmented isolation grouting. This solves the problems of disordered grout diffusion and inaccurate reinforcement in traditional grouting, and is especially suitable for geological features with layered distribution of karst caves.

[0043] The lifting device directly drives the grouting core tube to move up and down, and can precisely adjust the position of the grouting space 303 according to the layer height of the karst cave determined by the survey. Through the cyclic mode of positioning-grouting-moving-repositioning, it realizes the backward grouting from bottom to top, ensuring full-range filling from the bottom to the top of the karst cave. This conforms to the construction logic of gradually reinforcing from deep to shallow layers in karst treatment, and improves the overall bearing capacity of the karst cave.

[0044] The vent pipe 102 is fixed to the bottom inner side of the lower cover 101, runs through the grouting sleeve 1 axially and avoids the one-way valve of the rubber sleeve, forming a gas flow channel inside the pipe. When the lifting device moves the grouting core pipe and the lower annular sealing plug 302 up and down, the gas in the space below the sealing plug can freely interact with the outside through the vent pipe 102: gas is discharged when moving downward and gas is drawn in when moving upward, avoiding the formation of negative pressure or overpressure inside the pipe, preventing deformation of the grouting sleeve 1 and failure of the sealing plug, and reducing the problem of uneven grout diffusion caused by pressure fluctuations during grouting, ensuring that the grouting pressure is stable within the design range.

[0045] In summary, the independent grouting space 303 formed by the sealing plug and the precise positioning of the lifting device enable targeted grouting of karst cave sections at different depths, avoiding grout waste and ensuring that each karst cave layer is fully reinforced, thus meeting the design requirements for bearing capacity of karst caves below the tunnel centerline.

[0046] The pressure balancing effect of the vent pipe 102 effectively avoids the risk of grouting sleeve 1 rupture and borehole collapse caused by sudden pressure changes in the pipe during the movement of the grouting core pipe; the anti-backflow function of the rubber sleeve one-way valve reduces the incidence of construction accidents such as ground subsidence and grouting pipe blockage, which is in line with the construction principle of prioritizing safety and avoiding geological risks in karst treatment.

[0047] Segmented isolation grouting reduces rework issues such as cross-flow and backflow. The flexible control of the lifting device allows for segmented grouting of the entire hole without disassembling the grouting sleeve 1, shortening the construction cycle. At the same time, the stable pressure environment and directional grouting structure ensure that the grout fills the karst cave densely and diffuses evenly, improving the grout consolidation strength and ensuring the stability of the strata after karst treatment, providing a safe foundation for subsequent shield tunneling, bridge construction and other processes. Example 2

[0048] Please continue reading. Figures 8 to 10 As an improvement to the above embodiments, in actual construction, the grouting volume generally relies on experience for control, which easily leads to excessive or insufficient grouting. Excessive grouting can cause the pressure inside the karst cave and grouting casing 1 to exceed the standard, resulting in risks such as cracking of grouting casing 1, damage to the rubber sleeve check valve, and grout backflow blockage, and in severe cases, borehole collapse. Insufficient grouting cannot meet the bearing capacity requirements for stratum reinforcement. Furthermore, during the grouting process, the rubber sleeve check valve may not close in time due to the viscosity of the grout, causing grout leakage and backflow, affecting the segmented grouting effect. Therefore, the following improvements are made: The vent pipe 102 is located above the grouting sleeve 1 and is equipped with a detachable solenoid valve.

[0049] As a further improvement to the grouting core tube, the grouting core tube mainly consists of two parts: an inner core tube 2 and an outer sleeve 3. A wear-resistant sealing ring is provided at the sealing and expansion connection between the inner core tube 2 and the outer sleeve 3. The wear-resistant sealing ring is made of polyurethane or nitrile rubber and is used to prevent grout leakage in the grouting space 303.

[0050] Optionally, a grouting device can be connected above the inner core tube 2, for example, above the ground, via a hose; the inner core tube 2 and the outer sleeve 3 are telescopically connected, and a telescopic drive 4, such as a hydraulic cylinder, is provided between the inner core tube 2 and the outer sleeve 3; the fixed end of the hydraulic cylinder is connected to the inner core tube 2 located above the outer sleeve 3.

[0051] The telescopic end of the hydraulic cylinder is fixedly connected to the outer sleeve 3; the outer sleeve 3 is slidably connected to the inner core tube 2. The size of the grouting space 303 can be controlled by adjusting the vertical height of the upper annular sealing plug 301 through the telescopic drive component 4.

[0052] Furthermore, a lifting device is located at the top of the inner core tube 2 to control the up and down movement of the inner core tube 2, and a rotating device for controlling the rotation of the inner core tube 2 is provided at the top of the inner core tube 2.

[0053] The rotating device can be rotatably connected to the hose; the rotating device can be a drive motor as a power source. Specifically, external teeth are provided on the top circumference of the inner core tube 2, and the motor drives the external teeth and the inner core tube 2 located in the grouting sleeve 1 to rotate via a synchronous belt (not shown in the figure).

[0054] Furthermore, a gas supply pipe can be connected to the top of the vent pipe 102. This gas supply pipe can reverse the flow of pressurized gas into the space between the lower bottom cover 101 and the lower annular sealing plug 302. Of course, depending on the needs of use, when the solenoid valve is opened, the gas in the space can be attracted by high negative pressure and discharged outwards in a specific stage.

[0055] This embodiment adds an intermittent grouting process to the above-mentioned segmented grouting. Specifically, the telescopic end of the telescopic drive 4, which is the telescopic end of the hydraulic cylinder, is fixedly connected to the outer sleeve 3 through an elastic connector. The telescopic drive 4 can control the distance between the upper annular sealing plug 301 and the lower annular sealing plug 302 over a large distance. The elastic connector can be selected as a spring 402. An electromagnetic pin 401, or a hydraulic pin, is provided inside the telescopic end of the hydraulic cylinder. The fixed end of the electromagnetic pin 401 is connected to the telescopic end of the telescopic drive 4 and is located inside the spring 402. After the electromagnetic pin 401 retracts, the spring 402 forms an elastic connection between the inner core tube 2 and the outer sleeve 3. A first pressure sensor is provided at the connection between the spring 402 and the outer sleeve 3, and the pressure value in the current grouting space 303 can be obtained through the first pressure sensor.

[0056] The contraction and extension of the telescopic end of the electromagnetic pin 401 controls the short distance between the upper annular sealing plug 301 and the lower annular sealing plug 302. After each pressure test, it will be pushed forward again by the electromagnetic pin 401.

[0057] Under normal conditions, the electromagnetic pin 401 remains in an extended locked state. During the grouting process, after grouting for a period of time, the electromagnetic pin 401 contracts to appropriately increase the grouting space 303 between the upper annular sealing plug 301 and the lower annular sealing plug 302. Since the upper annular sealing plug 301 and the lower annular sealing plug 302 are sealed, when the upper annular sealing plug 301 moves upward, a certain negative pressure or other force is generated in the grouting space 303 to facilitate the retraction of the rubber sleeve check valve.

[0058] In use, the grouting sleeve 1 with a rubber-sleeved one-way valve is lowered into the borehole and fixed. The bottom is sealed by the bottom cover 101. The vent pipe 102 runs through the grouting sleeve 1 axially and is offset from the one-way valve. The top is equipped with a solenoid valve. The grouting core tube is composed of an inner core tube 2 and an outer sleeve 3 that are sealed and slidably connected. The two are connected by a hydraulic cylinder (telescopic drive 4) to achieve a large distance of extension and retraction. The extension end of the hydraulic cylinder is connected to the outer sleeve 3 via a spring 402 (elastic connector). An electromagnetic pin 401 is provided on the inner side of the spring 402. The outer side of the outer sleeve 3 is equipped with a lower annular sealing plug 302 and an upper annular sealing plug 301 to form a closed grouting space 303. The top of the inner core tube 2 is connected to the grouting equipment, lifting device and rotating device. The first pressure sensor is installed at the connection between the spring 402 and the outer sleeve 3 to sense the pressure of the grouting space 303 in real time. The inner core tube 2 is driven by the lifting device to accurately position the grouting space 303 to the lowest target grouting section. At this time, the electromagnetic pin 401 is in the extended locking state, fixing the initial size of the grouting space 303.

[0059] The grouting equipment is started, and grout is injected into the sealed grouting space 303 through the grouting port 202 on the inner core tube 2. The pressure gradually increases and compresses the spring 402. The first pressure sensor provides real-time pressure data. After grouting for a period of time, or when the pressure approaches the design upper limit, the electromagnetic pin 401 is controlled to retract, releasing the locking state. The elastic restoring force of the spring 402 drives the outer sleeve 3 and the upper annular sealing plug 301 to move upward, appropriately increasing the volume of the grouting space 303. Because the grouting space 303 remains sealed, a slight negative pressure is formed inside when the volume increases. On the one hand, this helps the rubber sleeve check valve overcome the grout viscosity and quickly retract, preventing grout backflow; on the other hand, it relieves the pressure inside the pipe, avoiding damage to the grouting sleeve 1 or the check valve due to excessive pressure. After the pressure stabilizes, the electromagnetic pin 401 extends and locks again, fixing the adjusted grouting space 303, and grouting continues. This cycle achieves intermittent grouting and dynamic space adjustment, allowing for more precise control of the grouting volume.

[0060] When the grouting core tube moves the lower annular sealing plug 302 up and down, the gas in the space below it interacts with the outside through the vent pipe 102, balancing the pressure inside the tube and preventing deformation or sealing failure of the grouting sleeve 1 due to sudden pressure changes. If the grouting pressure is insufficient, pressurized gas can be supplied through the gas supply pipeline at the top of the vent pipe 102 to assist the grout in diffusing into the karst fissures. If there is a risk of excessive grout, the solenoid valve can be opened to use high negative pressure to discharge the gas and some excess grout in the space in reverse, quickly relieving pressure. At the same time, the inner core tube 2 can be rotated by the rotating device (the rotating device is rotatably connected to the grouting hose to avoid pipe twisting), making the grout distribution in the grouting space 303 more uniform and improving the reinforcement effect.

[0061] After the current grouting section is completed, the inner core tube 2 is lifted upwards using a lifting device. The vent pipe 102 balances the pressure during the movement in real time, positioning the grouting space 303 to the next upper grouting section. The above grouting and adjustment steps are repeated to achieve backward segmented grouting from bottom to top. After all grouting sections are completed, the pipeline is flushed and the grouting core tube is pulled out. The grouting sleeve 1 is then sealed to complete the construction.

[0062] In summary, the intermittent grouting and dynamic spatial adjustment mechanism described above achieves a closed-loop operation of grouting-pressure stabilization-negative pressure retraction-re-grouting. The controllable negative pressure generated during the intermittent phase assists the one-way valve in rapid retraction, effectively preventing cross-flow and backflow of grout. The electromagnetic pin 401 actively adjusts the volume of the grouting space 303 by contracting, instantly alleviating pressure peaks within the pipe, avoiding the risk of casing rupture, and dynamically adjusting the intermittent frequency and grouting volume based on pressure sensor data, achieving targeted and precise reinforcement of karst caves of different shapes. The intermittent injection of grout in batches, with the preceding grout forming the framework and subsequent grout filling the shrinkage gaps, significantly improves the density, uniformity, and long-term structural stability of the karst cave filling, meeting the high-standard reinforcement requirements of complex karst strata.

[0063] As an optional technical solution, to address the issues of cement particles and aggregates in the grout easily depositing at the bottom of the grouting space 303 due to gravity in large-volume karst caves and long-term grouting scenarios, resulting in uneven grout concentration (manifested as excessively thick at the bottom and excessively thin at the top), blockage of the grouting port 202, and sticking of the inner core tube 2, the following improvements are added: The lifting and rotating devices at the top of the inner core tube 2 are retained. The rotating device is driven by a drive motor, a synchronous belt, and the external teeth at the top of the inner core tube 2. The rotating device is connected to the grouting hose by a rotary joint to avoid twisting the pipeline during rotation.

[0064] A second pressure sensor is added between the telescopic end of the lifting device and the inner core tube 2 to detect the tension value when the inner core tube 2 is pulled upward in real time.

[0065] A stirring blade is fixedly installed circumferentially at the bottom of the inner core tube 2. The arrangement direction of the stirring blade is adapted to the rotation direction, and it can disturb the bottom of the grouting space 303 as the inner core tube 2 rotates.

[0066] In this embodiment, the optional technical solution is only activated after the grouting of a section of the karst cave is completed, during the stage when the inner core tube 2 moves upward. The core point is to achieve anti-deposition and anti-jamming through tension detection, state judgment, and coordinated action. The specific working principle is as follows: After the grouting of the current grouting section is completed (reaching the designed grouting volume and pressure stabilization time), the grouting equipment is shut down, and preparation is made to lift the inner core tube 2 to the next grouting section; at this time, the lifting device is started, and the inner core tube 2 is lifted upward with the preset initial pulling force. The second pressure sensor synchronously collects the pulling force data in real time and transmits it to the ground control system.

[0067] The control system compares the collected tension value with a preset threshold (set according to parameters such as the weight of the grouting core tube, the friction of the sealing plug, and the viscosity of the normal grout). If the tension value is within the preset threshold range, it indicates that there is no obvious deposition or blockage in the grouting space 303, and the inner core tube 2 can be lifted upward normally by the lifting device. At the same time, the rotating device can be selectively activated as needed. After the rotating device is activated, it drives the inner core tube 2 and the bottom stirring blade to rotate synchronously. The stirring blade disturbs the grout and a small amount of sediment particles remaining at the bottom of the grouting space 303, preventing them from adhering to the sealing plug or the inner wall of the grouting sleeve 1. At the same time, the centrifugal force and shear force generated by the rotation cause the residual grout to resuspend. Combined with the lifting action of the lifting device, it drives the grout in the grouting space 303 to flow upward as a whole, reducing the sediment residue at the bottom and reducing the risk of blockage of the subsequent grouting port 202.

[0068] If the pulling force exceeds the preset threshold, the control system automatically determines that there is severe deposition below the inner core tube 2, such as a large accumulation of cement particles or a stuck seal. At this time, the lifting action is immediately stopped, and the back suction function of the grouting equipment is activated to back suction the grout to the outside through the inner core tube 2, reducing the amount of grout and the weight of residual deposits in the grouting space 303, and reducing the lifting load. After the back suction is completed, the lifting device is activated again for lifting, and the rotating device is activated simultaneously. The inner core tube 2 drives the bottom stirring blades to rotate at high speed. The stirring blades directly scrape and disturb the sediment layer at the bottom of the grouting space 303, breaking up the clumps of sediment particles and resuspending them in the remaining grout. In the grout; the frictional force generated by the rotation can reduce the friction between the sealing plug and the inner wall of the grouting sleeve 1. Combined with the lifting power of the lifting device, the inner core tube 2 moves upward more smoothly, avoiding damage to the grouting sleeve 1 or overload of the lifting device due to sediment jamming. After the inner core tube 2 is lifted to the target grouting section height, the rotation device and the lifting device are turned off, the second pressure sensor stops working, and subsequent grouting work is carried out. The above process is repeated only when the inner core tube 2 is lifted again, to ensure that the inner core tube 2 can move smoothly after each grouting section, while reducing the sediment residue in the grouting space 303, and ensuring the uniformity and continuity of subsequent grouting.

[0069] In summary, in traditional processes, simply lifting the core tube with a lifting device is insufficient to disturb the deposited slurry. However, when the rotating device drives the inner core tube 2 to rotate, it generates centrifugal and shear forces, breaking the static equilibrium of the slurry and causing the deposited particles to resuspend in the slurry. Simultaneously, in conjunction with the lifting action, a combined motion of rotational stirring and upward lifting is formed, causing the slurry in the grouting space 303 to flow upward as a whole, reducing residual deposits.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A retreating segmented sleeve valve grouting process for karst treatment, characterized in that, Includes the following steps: S1. Drilling construction: The positioning instrument is used to mark the drilling position, and the hole position error is ≤10cm; before drilling, the pipelines and obstacles are checked to a depth of 3-6m. The drilling rig is positioned and drilling begins, and the vertical deviation rate of the drilling hole is <1%. After drilling through special geological conditions, the parameters of the karst cave are recorded. After acceptance, the pipe is prepared for installation. S2. Equipment Layout: The grouting sleeve (1) is lowered into the borehole, and the bottom is sealed by the bottom cover (101). The sleeve material is filled between the pipe body and the borehole wall, and the grouting material is injected 1-2m below the ground. The grouting sleeve (1) is equipped with grouting ports (202) with one-way valves at different heights. After the grouting core tube is inserted, the grouting space (303) is formed by the upper and lower annular sealing plugs. The grouting core tube wall is equipped with corresponding grouting channels. The bottom cover (101) is fixed with the vent pipe (102). The top of the grouting core tube is connected to the grouting equipment and lifting device. S3, Grouting Positioning: The lifting device drives the grouting core tube to position it to the lowest grouting section. When moving, the pressure is balanced through the vent pipe (102); S4. Segmented grouting: Grout is injected into the grouting space (303) through the grouting channel, opens the one-way valve and seeps into the formation, and the vent pipe (102) continuously balances the pressure. After reaching the standard, the pressure is stabilized for a preset time. S5, Reverse grouting: Pull the grouting core pipe to the previous grouting section, and repeat S3~S4 to achieve segmented grouting from bottom to top; S6. Finishing treatment: flush the pipeline and pull out the grouting core pipe. Inject cement grout into the grouting sleeve (1) and smooth the hole after solidification. The grouting core tube includes an inner core tube (2) and an outer tube (3), which are sealed and telescopically connected and equipped with a telescopic drive (4); the telescopic drive (4) is connected to the outer tube (3) via an elastic connector, and has a built-in locking component. A first pressure sensor is provided at the elastic connector; the grouting is carried out in an intermittent manner, and the pressure is detected by the first pressure sensor. When the pressure reaches the standard, the locking component is unlocked to increase the grouting space (303), and after stabilization, it is relocked and grouting is repeated.

2. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, The end of the vent pipe (102) located above the grouting sleeve (1) is detachably equipped with a control valve. The top of the vent pipe (102) is selectively connected to a gas supply pipe. During grouting, if the grouting pressure is insufficient, pressurized gas is supplied to the vent pipe (102) through the gas supply pipe. If there is a risk of excessive grout, the control valve is opened to use negative pressure to discharge the gas and excess grout in the space in the reverse direction.

3. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, The inner core tube (2) is provided with a rotating device at the top. The rotating device is rotated and cooperates with the connecting pipe of the grouting equipment. The rotating device is used to drive the inner core tube (2) to drive the outer sleeve (3) to rotate synchronously. During the grouting process, the inner core tube (2) is driven to rotate by the rotating device, so that the grout in the grouting space (303) is evenly distributed.

4. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 3, characterized in that, A second pressure sensor is provided between the telescopic end of the lifting device and the inner core tube (2), and a stirring element is provided circumferentially at the bottom of the inner core tube (2); In step S5, when the inner core tube (2) is pulled up, the pulling pressure value is detected by the second pressure sensor. If the pulling force value is within the preset threshold range, the rotating device is selectively started to drive the inner core tube (2) and the stirring component to rotate, and the inner core tube (2) is pulled up in conjunction with the lifting device. If the tension value exceeds the preset threshold, the back suction function of the grouting equipment is activated to reduce the weight of grout and residue in the grouting space (303), and then the lifting device and rotating device are activated to drive the agitator to disturb the sediment layer and lift the inner core tube (2).

5. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, The one-way valve is a rubber sleeve one-way valve. When the grouting space (303) increases, a negative pressure is formed inside, which helps the rubber sleeve one-way valve to retract and block the grouting port (202).

6. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, The telescopic drive component (4) is a hydraulic cylinder, the elastic connector is a spring (402), and the locking component is an electromagnetic pin (401). The electromagnetic pin (401) is located inside the spring (402) and maintains an extended locking state under normal conditions.

7. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, In step S5, if the length of the grouting core tube pulled out exceeds the length of one section of the tube, the corresponding section of the core tube and the joint are removed, and the construction of the next grouting section continues.

8. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, In step S6, the cement grout injected into the grouting sleeve (1) has a water-cement ratio of 1:1, and the opening is smoothed with M15 mortar.

9. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 3, characterized in that, The rotating device includes a drive motor, a synchronous belt, and an external tooth located on the top circumferential direction of the inner core tube (2). The drive motor drives the external tooth to rotate through the synchronous belt, thereby driving the inner core tube (2) to rotate.

10. The grouting process for receding segmented sleeve valve pipes used in karst treatment according to claim 1, characterized in that, The inner core tube (2) and the outer sleeve tube (3) are provided with a wear-resistant sealing ring at the sealing and expansion connection to prevent grout leakage in the grouting space (303).

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