Self-adaptive treatment bag and method for pile foundation construction in karst area

Abstract

The application discloses a kind of karst area pile foundation construction self-adaptive treatment bag and method, belong to karst area pile foundation construction technical field.The bag includes annular bag, positioning bag, sleeve, gas injection pipe and grouting pipe;Annular bag is surrounded by upper bag cloth, lower bag cloth, inner bag cloth and outer bag cloth, for injecting slurry and expanding to form annular retaining wall;Positioning bag is embedded in the inner ring of annular bag, surrounded by upper positioning bag cloth, lower positioning bag cloth, inner bag cloth and sleeve, for inflation and expansion to push annular bag to move radially in karst cave and realize centering positioning;Gas injection pipe and grouting pipe are provided inside the sleeve.During preparation, the bag exhausts and is stored, after being lowered to karst cave in the field, first inflate the positioning bag to make it expand, push the annular bag to adaptively position and center in the karst cave, then grout the annular bag to form annular retaining wall.The application can realize pre-disposal and accurate positioning of karst cave, the annular retaining wall is regular, and multiple bags can also be fitted to simultaneously dispose multiple layers of karst cave, with efficient and reliable construction.

Description

Technical Field

[0001] This invention belongs to the field of karst area pile foundation construction technology, specifically relating to an adaptive treatment bag and method for karst area pile foundation construction. Background Technology

[0002] Karst areas are widely distributed in southwestern and south-central my country, and the strata often contain caves, dissolution fissures, and soil cavities of varying sizes and shapes. When drilling and grouting piles in such areas, drilling through karst cave regions often faces severe technical challenges: the cavities in the caves can cause sudden loss of mud, instability and collapse of the borehole walls, and in severe cases, even accidents such as drill bit burial and stuck drill bits.

[0003] Currently, the main construction and treatment methods for pile foundations penetrating karst caves in karst areas include the dumping method, grouting method, steel casing method, and concrete pouring method. The dumping method involves dumping rubble, clay, or bagged cement into the hole when grout leakage occurs after drilling through the karst cave, using an impact drill bit to force the filler into the cave and fissures to form a protective wall. This method is simple to operate and the materials are readily available, but for multi-layered or large-volume karst caves, repeated dumping results in huge material consumption, and the filler is easily washed away under flowing water conditions, making it difficult to guarantee the sealing effect. The grouting method involves injecting cement grout or cement-water glass grout into the karst cave through pre-drilled holes to fill the voids and consolidate the fractured rock mass. It is suitable for small to medium-sized karst caves, but for karst caves with good connectivity or large scale, the grout is easily lost along fissure channels, making it difficult to control the grouting volume and resulting in high costs. The steel casing method involves sinking steel casings section by section to the bottom of the karst cave to isolate the cavities, resulting in reliable pile quality, but the process is complex, requires high-end equipment, and is expensive. The concrete pouring method involves pouring low-grade concrete into the karst cave after it has been punctured, and then drilling again after it has solidified. However, this requires multiple machine shutdowns and waiting times, which severely restricts work efficiency.

[0004] In recent years, scholars both domestically and internationally have developed a series of novel bladder-type grouting treatment technologies, aiming to confine grouting materials inside a bladder for targeted sealing. Chinese patent application CN202422513297.3 discloses a bladder-type grouting device for sealing karst caves on the sidewalls of bored piles; Chinese patent application CN115679971A discloses a method for grouting at the location of a karst cave by binding the sealing bladder to a reinforcing cage. Among these, the "Bladder-type Grouting and Filling Method and Structure for Large-Volume Karst Pile Foundation Construction" (patent number CN201610306227.8) proposed by the Wuhan Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, is representative. This method designs a circular, frustum-shaped bladder based on the pile diameter and karst height. The bladder is lowered into the karst cave using ropes, and then air-filled lightweight materials are pumped in to fill and shape the bladder. However, this method still has obvious shortcomings: First, the bag can only be lowered and disposed of after the pile hole has been drilled to the karst cave, which is a "drilling and then processing" mode, affecting the continuity of construction; Second, after the large annular bag is lowered into the narrow pile hole, it is difficult to accurately position it at the expected location of the karst cave, and the bag may not be able to be formed into a regular annular shape as designed during the grouting process due to the constraints of the irregular space of the karst cave, resulting in a large uncertainty in the sealing effect.

[0005] In summary, the existing construction and treatment technologies for pile foundations penetrating karst caves in karst areas have the following problems: First, the traditional "drilling through and then treating" construction mode requires treatment only after the pile hole has penetrated the karst cave, resulting in poor construction continuity, high risks of hole collapse and drill bit burial, and repeated treatments severely affect work efficiency; Second, in the traditional grouting method, grout is severely lost along the fissure channels, making it difficult to control the grouting volume and resulting in high costs; Third, in the existing bladder grouting technology, it is difficult to accurately position the large annular bladder at the expected location of the karst cave after it is placed in the narrow pile hole. During the grouting filling process, the irregular space of the karst cave restricts the bladder to form a regular shape according to the design, resulting in a large uncertainty in the sealing effect. Summary of the Invention

[0006] This invention provides an adaptive treatment bag and method for pile foundation construction in karst areas. It aims to integrate an annular bag and a positioning bag into one unit, and use the inflation and expansion of the positioning bag to achieve adaptive positioning and centering of the bag in the karst cave. This ensures that the annular bag is formed in a regular shape according to a predetermined form, and moves the karst cave treatment process forward to before the pile foundation drilling, thereby achieving fixed-point sealing and wall protection.

[0007] To address the aforementioned technical problems, this invention provides an adaptive treatment bag for pile foundation construction in karst areas, the bag comprising: An annular sluice bag, composed of an upper sluice bag, a lower sluice bag, an inner sluice bag, and an outer sluice bag, is used to expand and form an annular protective wall after grout injection. The inner radius of the annular sluice bag is larger than the radius of the proposed pile foundation, ensuring an appropriate construction allowance between the grouted annular protective wall and the subsequently constructed pile foundation. Its outer radius is the sum of the inner radius and the radial thickness of the annular sluice bag; that is, the radial thickness of the annular sluice bag determines the wall thickness of the annular protective wall after grouting. The height of the annular sluice bag is greater than the vertical thickness of the karst cave, ensuring that the sluice bag can completely cover the vertical range of the karst cave, achieving complete sealing of the karst cave.

[0008] A positioning bag, embedded in the inner ring of the annular bag, is formed by an upper positioning bag fabric, a lower positioning bag fabric, an inner bag fabric, and a sleeve. The positioning bag is inflated to propel the annular bag radially within the cavern and achieve centering. The height of the positioning bag is the same as the height of the annular bag, ensuring that the positioning bag applies expansion force evenly along the entire height direction of the annular bag after inflation. The upper positioning bag fabric is fixed to the upper sealing ring, and the lower positioning bag fabric is fixed to the lower sealing ring to ensure the sealing of the positioning bag.

[0009] The sleeve is a rigid circular tube, which is disposed within the inner ring of the positioning bag. An upper sealing ring is provided at the upper end of the sleeve, and a lower sealing ring and a base are provided at the lower end of the sleeve. The sleeve provides support and guidance for the air injection pipe and the grouting pipe, while also providing rigid inner wall support for the positioning bag.

[0010] An air injection pipe is inserted inside the sleeve and communicates with the interior of the positioning bag. The air injection pipe is used to inflate the positioning bag with gas. The air injection pipe is set independently of the grouting pipe, so that the inflation and positioning operations do not interfere with each other. The positioning bag can maintain pressure continuously during the grouting process, providing stable lateral restraint for the annular bag.

[0011] The grouting pipe passes through the inside of the sleeve and communicates with the inside of the annular bag through the inner bladder. The grouting pipe is sealed to the inner bladder where it passes through, and is used to inject grout into the annular bag. The path of the grouting pipe through the inner bladder into the annular bag ensures that the grouting pipeline can deliver the grout into the annular bag without affecting its sealing. The sealed connection between the grouting pipe and the inner bladder ensures that no gas leakage occurs along the outer wall of the grouting pipe during inflation and pressure holding, thus allowing the positioning bag to continuously provide stable lateral restraint force to the annular bag, ensuring that the annular bag is formed correctly according to the design.

[0012] The annular bag and the positioning bag are in a vented and retracted state. This vented and retracted state refers to the state in which the annular bag and the positioning bag adhere to the surfaces of the casing, the air injection pipe, and the grouting pipe after the internal gas has been extracted. The radial dimension of the bag is significantly reduced after venting and retracting, facilitating its smooth lowering into the cavern location within a borehole with a limited diameter.

[0013] Furthermore, spacers are evenly spaced along the height direction between the inner and outer lining fabrics. Each spacer is an annular sheet structure, with its inner radius matching the inner radius of the annular bag and its outer radius matching the outer radius of the annular bag. Multiple grout perforations are provided on the spacers. The spacers divide the interior of the annular bag into multiple interconnected grouting chambers along the height direction, ensuring uniform distribution of the grout along the height direction within the annular bag during grouting. This prevents uneven bag expansion caused by grout deposition due to its own weight. The grout perforations maintain communication between the grouting chambers, ensuring uniform distribution of the grout throughout the entire annular bag.

[0014] Furthermore, multiple layers of positioning pull lines are provided between the inner bladder and the sleeve. Adjacent layers of positioning pull lines are spaced 0.5 to 1.0 meters apart along the axial direction of the sleeve. Each layer of positioning pull lines includes 6 to 16 strip-shaped flexible pull lines, arranged radially from the sleeve towards the inner bladder. When the positioning bag inflates, the positioning pull lines pull the inner bladder towards the sleeve, ensuring uniform force on the inner bladder in all directions during inflation, and allowing for precise centering of the annular bag. The radial arrangement ensures balanced force in all directions, preventing the annular bag from becoming eccentric during positioning.

[0015] Furthermore, the slurry perforations are arranged at equal intervals along the circumference of the septum, with a number of four to eight perforations. The diameter of each perforation is one-fifth to one-third of the radial width of the septum. This reasonable arrangement of the number and diameter of the perforations ensures smooth flow of the slurry between the chambers while avoiding weakening of the radial constraint of the septum on the septum due to excessively large openings.

[0016] Furthermore, the sleeve is provided with retaining rings at axial intervals of 0.5 meters to 1.0 meter, which are used to fix the end of the positioning cable. The retaining rings provide a clear anchor point for the positioning cable, ensuring that the positioning cable can effectively transmit tension when the positioning bag is inflated.

[0017] Furthermore, the upper end of the air injection pipe is equipped with an air injection pipe switch, and the lower end of the air injection pipe is connected to the air injection tail pipe through an air injection pipe connecting pipe. The lower end of the air injection tail pipe is closed, and an air outlet is provided on the side wall of the air injection tail pipe. The air injection tail pipe passes through the base and extends into the interior of the positioning bag. The upper end of the grouting pipe is equipped with a grouting pipe switch, and the lower end of the grouting pipe is connected to the grouting tail pipe through a grouting pipe connecting pipe. The lower end of the grouting tail pipe is closed, and an grout outlet is provided on the side wall of the grouting tail pipe. The grouting tail pipe passes through the base, the positioning bag, and the inner bag fabric and then extends into the interior of the annular bag. The air injection pipe connecting pipe and the grouting pipe connecting pipe respectively lock the base to prevent the sleeve from sliding downward. The air injection pipe switch and the grouting pipe switch are used to control the air inflation operation and the grouting operation, respectively. The lower end of the air injection tail pipe and the grouting tail pipe are closed, and the side wall is opened with an air outlet or a grout outlet, so that the gas or grout enters the corresponding bag through the side wall hole.

[0018] Furthermore, the air injection pipe is composed of multiple sections of rigid circular pipe connected together, with adjacent sections connected by threads or heat fusion; the grouting pipe is also composed of multiple sections of rigid circular pipe connected together, with adjacent sections connected by threads or heat fusion; the air injection pipe connecting pipe and the grouting pipe connecting pipe each independently include a rigid section and a soft section, with the soft section having a telescopic length of 0.5 meters to 1.0 meter. This multi-section pipe connection method allows the lengths of the air injection pipe and the grouting pipe to be flexibly adjusted according to the drilling depth, suitable for treating karst caves of different depths; the telescopic capacity of the soft section can assist in the small-amplitude up-and-down adjustment of the positioning bag during inflation, allowing the bag to move to the optimal treatment position within the karst cave. During the expansion of the annular bag during grouting, it can compensate for the relative displacement between the air injection tailpipe and the grouting tailpipe and the air injection pipe / grouting pipe caused by the radial expansion of the bag, preventing damage to the pipe connections due to stress.

[0019] Furthermore, both the annular pouch and the positioning pouch are made of sealing material. The sealing material ensures that the pouches can be inflated and pressurized, and can be vacuum-sealed.

[0020] The present invention also provides an adaptive treatment method for karst pile foundation construction using the above-mentioned adaptive treatment bag, the method comprising the following steps: S1: A guide borehole is drilled at the center of the proposed pile foundation. The depth of the guide borehole exceeds the bottom of the karst cave by 0.2 to 0.5 meters, and the diameter of the guide borehole is greater than the maximum radial dimension of the adaptive treatment bag for karst pile foundation construction in the venting and storage state. By pre-drilling a guide borehole at the center of the proposed pile foundation, the karst cave treatment process is moved forward to before the pile foundation drilling, avoiding the construction interruption and borehole collapse risks associated with drilling through the karst cave in traditional methods.

[0021] S2: The vented and collected karst area pile foundation adaptive treatment bag is lowered through the guide borehole to the position corresponding to the vertical range of the karst cave. The radial dimension of the vented and collected bag is significantly reduced, allowing it to be smoothly lowered to the karst cave location through the guide borehole.

[0022] S3: Gas is injected into the positioning bag through the injection pipe. The positioning bag expands and pushes the annular bag radially within the cave until the annular bag is aligned with the guide borehole. After inflation, the positioning bag forms a cylindrical airbag centered on the casing. Its radial expansion force pushes the annular bag towards the cave wall, achieving adaptive and precise positioning and alignment of the annular bag within the cave. This effectively solves the problem of accurate positioning of existing large annular bags after deployment.

[0023] S4: Grout is injected into the annular bag through the grouting pipe. The grout fills the annular bag and causes it to expand outward, forming an annular protective wall around the proposed pile foundation. The sequence of positioning followed by grouting ensures that the annular bag is in the predetermined position before grouting. During the grouting process, the positioning bag is continuously pressurized, providing stable lateral constraints for the annular bag and ensuring that it forms a regular annular shape, avoiding the adverse effects of irregular spaces in the karst cave on the bag's formation.

[0024] S5: After the slurry reaches the design strength, the pile foundation drilling, mud wall protection, hole cleaning, lowering of the reinforcing cage, and concrete pouring are carried out. At this time, the annular retaining wall provides reliable hole wall protection for subsequent pile foundation construction, effectively avoiding accidents such as hole collapse and slurry leakage.

[0025] Furthermore, when the proposed pile foundation passes through multiple karst caves, an adaptive treatment bag for karst pile foundation construction is independently fitted onto the air injection pipe and the grouting pipe at the location corresponding to each karst cave. Each of these adaptive treatment bags is lowered along with the air injection pipe and the grouting pipe in the same installation process. After each bag reaches its predetermined position corresponding to its respective karst cave, it is inflated and positioned, and grout is injected into each annular bag to treat multiple karst caves. By completing the simultaneous treatment of multiple karst caves in a single lowering operation, layer-by-layer treatment is eliminated, significantly improving construction efficiency.

[0026] Compared with existing technologies, this invention changes the approach from "treatment after drilling" to "pre-treatment." Before pile foundation drilling, pre-drilling is used to treat the karst caves, forming a ring-shaped protective wall before pile foundation construction. This avoids the risks of borehole collapse and grout leakage during construction, ensuring the continuity and safety of the project. The inflated positioning bag automatically moves the ring-shaped bag to a position concentric with the borehole within the limited space of the karst cave. The radial arrangement of the positioning lines ensures uniform force on the ring-shaped bag in all directions, achieving precise positioning and centering of the bag within the karst cave. The integrated bag structure's pre-positioning and subsequent grouting process ensures the ring-shaped bag is in the predetermined position before grouting. During grouting, the positioning bag maintains continuous pressure, providing stable lateral constraints and ensuring the ring-shaped bag is formed neatly according to the design. For complex situations where pile foundations pass through multiple karst caves, multiple bags can be fitted onto the air injection pipe and grouting pipe, each bag corresponding to a different karst cave location, achieving simultaneous treatment of multiple layers of karst caves in one go. The bags can be prefabricated in the factory, vented and stored, and then installed on site. The quality is controllable and the operation is simple. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a perspective view of the bag structure of the present invention.

[0028] Figure 2 This is a schematic cross-sectional view of the bag structure of the present invention.

[0029] Figure 3 This is a schematic diagram of the annular sac in the sac of the present invention after the air is released.

[0030] Figure 4 This is a schematic diagram of the positioning bag in the bag of the present invention after the air is vented.

[0031] Figure 5 This is a schematic diagram of the proposed pile foundation and guide borehole in an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of the bag installation in an embodiment of the present invention.

[0033] Figure 7 This is a schematic diagram of the positioning bag being inflated and positioned in an embodiment of the present invention.

[0034] Figure 8 This is a schematic diagram of grouting in an annular bladder in an embodiment of the present invention.

[0035] Figure 9This is a schematic diagram showing the completion of pile foundation pouring in an embodiment of the present invention.

[0036] Figure 10 This is a schematic diagram illustrating the treatment of the proposed pile foundation passing through two karst caves in an embodiment of the present invention.

[0037] The meanings of the labels in the attached figures are as follows: 1 is an annular bag; 1.1 is the upper bag fabric; 1.2 is the lower bag fabric; 1.3 is the inner bag fabric; 1.4 is the outer bag fabric; 1.5 is the bag spacer; 1.6 is the grout penetration hole; 2 is a positioning bag; 2.1 is the upper positioning bag fabric; 2.2 is the lower positioning bag fabric; 2.3 is the positioning pull line; 3 is the sleeve; 3.1 is the upper sealing ring; 3.2 is the lower sealing ring; 3.3 is the fixing ring; 3.4 is the base; 4 is the air injection pipe; 4.1 is the air injection pipe switch; 4.2 is the air injection pipe connecting pipe; 4.3 is the air injection tail pipe; 5 is the grouting pipe; 5.1 is the grouting pipe switch; 5.2 is the grouting pipe connecting pipe; 5.3 is the grouting tail pipe; 6 is the karst cave; 7 is the proposed pile foundation; 8 is the guide borehole; 9 is the bag after venting and collection; 10 is the pile foundation. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are schematic diagrams and do not constitute a limitation on the invention.

[0039] Example 1: Bag Structure like Figure 1 and Figure 2 As shown in the figure, this embodiment provides an adaptive treatment bag for pile foundation construction in karst areas. The bag consists of an annular bag 1, a positioning bag 2, a sleeve 3, an air injection pipe 4, and a grouting pipe 5.

[0040] The annular bag 1 is formed by an upper bag 1.1, a lower bag 1.2, an inner bag 1.3, and an outer bag 1.4. The annular bag 1 expands to form an annular protective wall after grout injection. The annular bag 1 is made of sealing material, capable of being inflated and pressurized, and can be vacuum-sealed, able to withstand grouting pressure and the constraint reaction force of the cave wall. The inner radius of the annular bag 1 is larger than the radius of the proposed pile foundation 7, ensuring an appropriate construction allowance between the grout-formed annular protective wall and the subsequently constructed pile foundation; its outer radius is the sum of the inner radius and the radial thickness of the annular bag 1, meaning the radial thickness of the annular bag 1 determines the wall thickness of the annular protective wall after grouting. The height of the annular bag 1 is greater than the vertical thickness of the cave 6, ensuring that the bag can completely cover the vertical range of the cave 6, achieving complete sealing of the cave. The annular bag 1 and the positioning bag 2 have an exhaust and storage state. The exhaust and storage state refers to the state in which the annular bag 1 and the positioning bag 2 adhere to the surface of the casing 3, the air injection pipe 4 and the grouting pipe 5 after the internal gas is extracted. This greatly reduces the radial size of the bag and makes it easier to lower into narrow boreholes.

[0041] Spacer panels 1.5 are evenly spaced along the height direction between the inner bladder 1.3 and the outer bladder 1.4. Each spacer panel 1.5 has an annular structure, with its inner ring radius matching that of the annular bladder 1 and its outer ring radius matching that of the annular bladder 1, ensuring that the spacer panel 1.5 can completely divide the interior of the annular bladder 1 into multiple grouting chambers along the height direction. Multiple grout-permeable holes 1.6 are provided on the spacer panel 1.5, with each hole 1.6 evenly spaced along the circumference of the spacer panel 1.5. The number of grout-permeable holes 1.6 is 4 to 8, and the diameter of each hole 1.6 is one-fifth to one-third of the radial width of the spacer panel 1.5. The septum 1.5 divides the interior of the annular bag 1 into multiple interconnected grouting chambers along the height direction, ensuring that the grout is evenly distributed along the height direction within the annular bag 1 during grouting, and preventing the grout from depositing downwards due to its own weight, which would cause uneven expansion of the bag; the grout passage 1.6 keeps the grout connected between the grouting chambers of each layer, ensuring that the grout can be evenly distributed throughout the entire annular bag 1.

[0042] The positioning bag 2 is formed by an upper positioning bag fabric 2.1, a lower positioning bag fabric 2.2, an inner bag fabric 1.3, and a sleeve 3. The positioning bag 2 is used for inflation to push the annular bag 1 radially within the cavern 6 and achieve centering positioning. The positioning bag 2 is embedded in the inner ring of the annular bag 1, and its height is the same as that of the annular bag 1. The positioning bag 2 is made of sealing material, capable of inflation and pressure holding and being vacuum sealed. Multiple layers of positioning pull lines 2.3 are provided between the inner bag fabric 1.3 and the sleeve 3. The positioning pull lines 2.3 are strip-shaped flexible pull lines, and their length is adapted to the radial distance from the outer wall of the sleeve 3 to the inner bag fabric 1.3. One end of the positioning pull line 2.3 is connected to the fixing ring 3.3, and the other end is sewn to the inner bag fabric 1.3. Each layer is equipped with 6 to 16 positioning pull lines 2.3. The positioning pull lines 2.3 of adjacent layers are spaced 0.5 to 1.0 meters apart along the axial direction of the sleeve 3. Each positioning pull line 2.3 is arranged radially towards the inner bladder 1.3 with the sleeve 3 as the center. When the positioning bladder 2 is inflated, the positioning pull lines 2.3 pull the inner bladder 1.3 taut towards the sleeve 3, ensuring uniform force in all directions during inflation and precise centering of the annular bladder 1. This radial arrangement ensures balanced force in all directions and prevents the annular bladder 1 from becoming eccentric during positioning.

[0043] The sleeve 3 is a rigid circular tube, located within the inner ring of the positioning bag 2, and its length is approximately equal to the height of the annular bag 1. The upper end of the sleeve 3 has an upper sealing ring 3.1 for fixing and sealing the upper positioning bag fabric 2.1; the lower end has a lower sealing ring 3.2 and a base 3.4. The lower sealing ring 3.2 is used to fix and seal the lower positioning bag fabric 2.2, and the base 3.4 is used to seal the bottom of the positioning bag 2 and provide an insertion channel for the air injection pipe 4 and the grouting pipe 5. The sleeve 3 has fixing rings 3.3 spaced axially at intervals of 0.5 meters to 1.0 meter for fixing the end of the positioning pull line 2.3, ensuring that the positioning pull line 2.3 has a clear anchoring point when the positioning bag 2 is inflated, thereby ensuring the centering accuracy of the annular bag 1.

[0044] The air injection pipe 4 passes through the inside of the casing 3 and communicates with the inside of the positioning bag 2 to inflate the positioning bag 2 with gas. An air injection pipe switch 4.1 is located at the upper end of the air injection pipe 4 to control the inflation operation and pressure holding. The lower end of the air injection pipe 4 is connected to the air injection tail pipe 4.3 via an air injection pipe connecting pipe 4.2. The lower end of the air injection tail pipe 4.3 is closed, and an air outlet is provided on its side wall. The air injection tail pipe 4.3 passes through the base 3.4 and extends into the inside of the positioning bag 2. The air injection pipe 4 is composed of multiple sections of rigid round pipe connected together. Adjacent sections of the air injection pipe 4 are connected by threads or heat fusion to adapt to drilling requirements at different depths. The air injection pipe connecting pipe 4.2 includes a rigid section and a flexible section. The rigid section connects to the air injection pipe 4 and locks the base 3.4 to prevent the casing 3 from sliding downwards. The flexible section connects to the air injection tail pipe 4.3 and has a telescopic length of 0.5 meters to 1.0 meter. The air injection pipe 4, the air injection pipe connecting pipe 4.2, and the air injection tail pipe 4.3 are connected and sealed by threads and rubber gaskets. The expansion and contraction capacity of the soft section can be used to adjust the positioning bag 2 by small-amplitude lifting and pulling during inflation, so that the bag moves to the optimal position within the cavern 6, ensuring that the annular bag 1 is precisely aligned with the vertical range of the cavern 6; during the grouting expansion of the annular bag 1, it can compensate for the relative displacement between the air injection tail pipe 4.3 and the air injection pipe 4 caused by the radial expansion of the bag, avoiding damage to the pipe connection due to stress.

[0045] The grouting pipe 5 passes through the inside of the sleeve 3, through the inner bladder 1.3, and communicates with the inside of the annular bag 1 for injecting grout into the annular bag 1. The grouting pipe 5 is sealed to the inner bladder 1.3 where it passes through, ensuring that the positioning bag 2 will not leak gas along the outer wall of the grouting pipe 5 during inflation and pressure holding. This allows the positioning bag 2 to continuously provide a stable lateral restraint force to the annular bag 1, ensuring that the annular bag 1 is formed in a regular shape according to the design. The upper end of the grouting pipe 5 is equipped with a grouting pipe switch 5.1 for controlling the grouting operation and pressure holding. The lower end of the grouting pipe 5 is connected to the grouting tail pipe 5.3 through the grouting pipe connecting pipe 5.2. The lower end of the grouting tail pipe 5.3 is closed, and the side wall of the grouting tail pipe 5.3 has a grout outlet hole. The grouting tail pipe 5.3 passes through the base 3.4, the positioning bag 2, and the inner bladder 1.3 and then extends into the inside of the annular bag 1. The grouting pipe 5 is composed of multiple sections of rigid round pipe connected together. Adjacent sections of the grouting pipe 5 are connected by threads or heat fusion. The grouting pipe connecting pipe 5.2 includes a rigid section and a flexible section. The rigid section connects to the grouting pipe 5 and clamps the base 3.4 to prevent the sleeve 3 from slipping. The flexible section connects to the grouting tail pipe 5.3 and has a telescopic length of 0.5 meters to 1.0 meter. The grouting pipe 5, the grouting pipe connecting pipe 5.2, and the grouting tail pipe 5.3 are connected and sealed by threads and rubber gaskets. The telescopic capacity of the flexible section is the same as that of the flexible section of the air injection pipe connecting pipe 4.2: it helps to adjust the position of the positioning bag 2 during inflation and compensates for the relative displacement between the grouting tail pipe 5.3 and the grouting pipe 5 during the grouting expansion of the annular bag 1.

[0046] Example 2: Pouch making and storage This embodiment provides a method for manufacturing and storing the aforementioned pouch.

[0047] The first step is to sew and glue the annular bag 1, the positioning bag 2, and the sleeve 3. During the sewing and gluing process, the air injection pipe connecting pipe 4.2, the air injection tail pipe 4.3, the grouting pipe connecting pipe 5.2, and the grouting tail pipe 5.3 are sewn and glued together to the base 3.4 of the sleeve 3. Then, the temporary air injection pipe and the temporary grouting pipe are installed and connected. The annular bag 1 and the positioning bag 2 are inflated, and the sealing of the annular bag 1 and the positioning bag 2 is checked to ensure that there are no air leakage defects in the bags.

[0048] The second step involves extracting air from the annular bag 1 through the temporary grouting pipe. After all the air has been extracted, the temporary grouting pipe switch is closed. Then, air is extracted from the positioning bag 2 through the temporary air injection pipe. After all the air has been extracted, the temporary air injection pipe switch is closed. The vented annular bag 1 and positioning bag 2 are tightly fitted to the surfaces of the casing 3, grouting pipe 5, and air injection pipe 4, as shown below. Figure 3 and Figure 4 As shown, the radial dimension of the bladder is significantly reduced, making it easier to lower into narrow boreholes.

[0049] The third step involves fitting a restraint net over the annular bag 1 and the positioning bag 2 after the air is vented. The restraint net is open at the bottom and has a pull rope attached to the top; pulling the rope allows the restraint net to detach from the annular bag 1 and the positioning bag 2. Loosen the connecting nuts between the air injection pipe 4.2 and the temporary air injection pipe, as well as the connecting nuts between the grouting pipe 5.2 and the temporary grouting pipe. Remove the temporary air injection pipe and the temporary grouting pipe to complete the storage, forming the air-vented and stored bag 9.

[0050] Example 3: Construction Method for Treating Single-Layer Karst Caves like Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown in the figure, this embodiment provides an adaptive treatment method for pile foundation construction in karst areas using the above-mentioned bag.

[0051] First, the distribution of cave 6 was determined based on geological survey data, including its vertical thickness, depth, and filling condition. For example... Figure 5As shown, a guide borehole 8 is drilled at the center of the proposed pile foundation 7. The depth of the guide borehole 8 exceeds the bottom of the karst cave 6 by 0.2 to 0.5 meters to ensure that the venting bag can completely cover the vertical range of the karst cave 6; the diameter of the guide borehole 8 is larger than the maximum radial dimension of the venting bag 9 after venting and storage to ensure that the venting bag can be smoothly lowered. The vertical thickness of the karst cave 6 is determined according to the geological survey data, and the height of the annular venting bag 1 and the lengths of the air injection pipe 4 and the grouting pipe 5 are determined according to this vertical thickness. The venting bag is then manufactured and stored in the factory according to the methods of Example 1 and Example 2.

[0052] like Figure 6 As shown, the venting bag is installed. The first section of the air injection pipe 4 and the first section of the grouting pipe 5 are connected to the vented and collected venting bag 9. The vented and collected venting bag 9 is then flipped over and hoisted into the guide borehole 8. The air injection pipe 4 and the grouting pipe 5 are extended at the borehole opening, and the restraining net rope is released, allowing the vented and collected venting bag 9 to gradually descend to the position of the karst cave 6. By extending the air injection pipe 4 and the grouting pipe 5, this method can be applied to the treatment of karst caves of any depth.

[0053] like Figure 7 As shown, after the air-filled and collected bag 9 reaches the designated position, the rope of the restraining net is pulled to detach the restraining net from the air-filled and collected bag 9. Gas is then injected into the positioning bag 2 through the air injection pipe 4. The positioning bag 2 gradually expands to form a cylindrical airbag centered on the guide borehole 8, pushing the annular bag 1 towards the wall of the cave 6 and aligning the annular bag 1 with the guide borehole 8. The air injection pipe switch 4.1 is then closed to complete the positioning. The inflation positioning function of the positioning bag 2 effectively solves the problem that existing large annular bags are difficult to accurately position in the expected location of the cave after being lowered into narrow pile holes.

[0054] like Figure 8 As shown, grouting is performed in the annular bag 1. Concrete grout is injected into the annular bag 1 through the grouting pipe 5. The grout enters the interior of the annular bag 1 through the grout outlet hole on the side wall of the grouting tail pipe 5.3, and fills upwards layer by layer through the grout penetration holes 1.6 on the spacers 1.5 of each layer. The grout gradually fills the annular bag 1 and expands outwards, forming a regular annular protective wall around the proposed pile foundation 7. During the grouting process, the positioning bag 2 maintains continuous pressure to provide stable lateral restraint for the annular bag 1, ensuring that the annular bag 1 is formed according to the design shape. After grouting is completed, the grouting pipe switch 5.1 is closed.

[0055] Once the grout reaches its design strength (usually requiring 3 to 7 days of curing, the exact time depending on the grout mix ratio and site temperature), conventional methods can be used for pile foundation construction. Figure 9 As shown, the process involves drilling, mud wall protection, hole cleaning, lowering the reinforcing cage, and concrete pouring to form pile foundation 10. At this point, the annular retaining wall provides reliable hole wall protection for subsequent pile foundation construction, effectively preventing accidents such as hole collapse and grout leakage.

[0056] Example 4: Construction Method for Simultaneous Treatment of Multi-Layer Karst Caves like Figure 10 As shown in the figure, this embodiment provides a construction method for simultaneously treating multi-layered karst caves using the aforementioned bag.

[0057] For the proposed pile foundation 7 that passes through multiple karst caves 6, a separate gas inlet is independently installed on the air injection pipe 4 and grouting pipe 5 at the location corresponding to each karst cave 6. Each gas inlet is independently connected to the air injection pipe 4 and grouting pipe 5, meaning each gas inlet has an independent air injection pipe connecting pipe 4.2, air injection tail pipe 4.3, grouting pipe connecting pipe 5.2, and grouting tail pipe 5.3. The gas inlets are arranged sequentially along the length of the air injection pipe 4 and grouting pipe 5, and the spacing between adjacent gas inlets is determined according to the interlayer spacing of each karst cave 6.

[0058] During construction, each air-filled bag 9, along with the air injection pipe 4 and grouting pipe 5, is lowered into the guide borehole 8, positioning each bag at its respective target karst cave 6. Upon reaching the designated depth, the restraining net ropes of each bag are pulled sequentially during the same installation process to detach the nets from the bags. Air is then sequentially injected into each positioning bag 2 through the air injection pipe 4, causing each positioning bag 2 to expand and position itself within its corresponding karst cave 6. Subsequently, concrete grout is sequentially injected into each annular bag 1 through the grouting pipe 5, forming annular protective walls within each annular bag 1 within its corresponding karst cave 6.

[0059] Using the above method, multiple karst caves can be treated simultaneously in a single lowering operation, eliminating the need for layer-by-layer treatment and significantly improving construction efficiency. Once all layers of grout have reached their designed strength, subsequent pile foundation construction can proceed.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and principle of the present invention, such as adjusting the interlayer spacing of the positioning wires, changing the number of septa and the arrangement of the grouting holes, and adjusting the air injection pressure and grouting pressure according to the actual project. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive treatment bag for pile foundation construction in karst areas, characterized in that, include: An annular bag (1) is formed by an upper bag cloth (1.1), a lower bag cloth (1.2), an inner bag cloth (1.3) and an outer bag cloth (1.4). The annular bag (1) is used to expand and form an annular protective wall after the slurry is injected. Positioning bag (2), the positioning bag (2) is embedded in the inner ring of the annular bag (1), the positioning bag (2) is surrounded by an upper positioning bag cloth (2.1), a lower positioning bag cloth (2.2), the inner bag cloth (1.3) and a sleeve (3), the positioning bag (2) is used to inflate and expand to push the annular bag (1) to move radially in the cave (6) and achieve centering positioning; The sleeve (3) is a rigid round tube. The sleeve (3) is set in the inner ring of the positioning bag (2). The upper end of the sleeve (3) is provided with an upper sealing ring (3.1), and the lower end of the sleeve (3) is provided with a lower sealing ring (3.2) and a base (3.4). The gas injection tube (4) is inserted inside the sleeve (3) and communicates with the inside of the positioning bag (2). The gas injection tube (4) is used to fill the positioning bag (2) with gas. Grouting pipe (5), the grouting pipe (5) is inserted inside the sleeve (3), the grouting pipe (5) passes through the inner bladder (1.3) and communicates with the inside of the annular bag (1), the grouting pipe (5) is sealed to the inner bladder (1.3) where it passes through, the grouting pipe (5) is used to inject grout into the annular bag (1); The inner radius of the annular bag (1) is greater than the radius of the proposed pile foundation (7), the outer radius of the annular bag (1) is the sum of the inner radius and the radial thickness of the annular bag (1), and the height of the annular bag (1) is greater than the vertical thickness of the karst cave (6). The annular bag (1) and the positioning bag (2) have an exhaust and storage state. The exhaust and storage state refers to the state in which the annular bag (1) and the positioning bag (2) adhere to the surface of the sleeve (3), the air injection pipe (4) and the grouting pipe (5) after the internal gas is extracted.

2. The adaptive treatment bag for karst pile foundation construction according to claim 1, characterized in that, The height of the positioning bag (2) is the same as the height of the annular bag (1), the upper positioning bag cloth (2.1) is fixed to the upper sealing ring (3.1), and the lower positioning bag cloth (2.2) is fixed to the lower sealing ring (3.2).

3. The adaptive treatment bag for karst area pile foundation construction according to claim 1, characterized in that, Spacer sheets (1.5) are provided at equal intervals along the height direction between the inner lining (1.3) and the outer lining (1.4). The spacer sheets (1.5) are annular sheet structures. The inner ring radius of the spacer sheets (1.5) is the same as the inner ring radius of the annular bag (1). The outer ring radius of the spacer sheets (1.5) is the same as the outer ring radius of the annular bag (1). The spacer sheets (1.5) are provided with a plurality of slurry perforations (1.6).

4. The adaptive treatment bag for karst area pile foundation construction according to claim 1, characterized in that, Multiple layers of positioning pull lines (2.3) are provided between the inner lining fabric (1.3) and the sleeve (3). The positioning pull lines (2.3) of adjacent layers are spaced 0.5 meters to 1.0 meters apart along the axial direction of the sleeve (3). Each layer of positioning pull lines (2.3) includes 6 to 16 strip-shaped flexible pull lines. Each positioning pull line (2.3) is arranged radially from the sleeve (3) toward the inner lining fabric (1.3).

5. The adaptive treatment bag for karst area pile foundation construction according to claim 3, characterized in that, Each of the slurry-permeable holes (1.6) is arranged at equal intervals along the circumference of the septum (1.5), and the number of slurry-permeable holes (1.6) is 4 to 8. The diameter of each slurry-permeable hole (1.6) is one-fifth to one-third of the radial width of the septum (1.5).

6. The adaptive treatment bag for karst area pile foundation construction according to claim 4, characterized in that, The sleeve (3) is provided with fixing rings (3.3) at axial intervals of 0.5 meters to 1.0 meters. The fixing rings (3.3) are used to fix the end of the positioning pull line (2.3).

7. The adaptive treatment bag for karst pile foundation construction according to claim 1, characterized in that, The upper end of the air injection pipe (4) is provided with an air injection pipe switch (4.1), and the lower end of the air injection pipe (4) is connected to the air injection tail pipe (4.3) through an air injection pipe connecting pipe (4.2). The lower end of the air injection tail pipe (4.3) is closed, and an air outlet is provided on the side wall of the air injection tail pipe (4.3). The air injection tail pipe (4.3) passes through the base (3.4) and extends into the interior of the positioning bag (2). The upper end of the grouting pipe (5) is provided with a grouting pipe switch (5.1), and the lower end of the grouting pipe (5) is connected to the air injection tail pipe (4.3) through an air injection pipe connecting pipe (4.2). The grouting pipe connecting pipe (5.2) is connected to the grouting tail pipe (5.3). The lower end of the grouting tail pipe (5.3) is closed. The side wall of the grouting tail pipe (5.3) is provided with a grout outlet hole. The grouting tail pipe (5.3) passes through the base (3.4), the positioning bag (2) and the inner bag cloth (1.3) and then extends into the interior of the annular bag (1). The air injection pipe connecting pipe (4.2) and the grouting pipe connecting pipe (5.2) respectively lock the base (3.4) to prevent the sleeve (3) from sliding downward.

8. The adaptive treatment bag for karst pile foundation construction according to claim 7, characterized in that, The air injection pipe (4) is composed of multiple sections of rigid round pipe connected together, and adjacent sections of the air injection pipe (4) are connected by thread or heat fusion; the grouting pipe (5) is composed of multiple sections of rigid round pipe connected together, and adjacent sections of the grouting pipe (5) are connected by thread or heat fusion; the air injection pipe connecting pipe (4.2) and the grouting pipe connecting pipe (5.2) each independently include a rigid section and a soft section, and the soft section has a telescopic length of 0.5 meters to 1.0 meters.

9. An adaptive treatment method for pile foundation construction in karst areas, characterized in that, The adaptive treatment bag for karst area pile foundation construction according to any one of claims 1 to 8 includes the following steps: S1: Drill a guide hole (8) at the center of the proposed pile foundation (7). The depth of the guide hole (8) exceeds the bottom of the karst cave (6) by 0.2 to 0.5 meters. The diameter of the guide hole (8) is greater than the maximum radial dimension of the adaptive treatment bag for karst pile foundation construction in the exhaust and storage state. S2: The karst area pile foundation construction adaptive treatment bag after exhaust is lowered through the guide borehole (8) to the position corresponding to the vertical range of the karst cave (6); S3: Gas is injected into the positioning bag (2) through the gas injection pipe (4), the positioning bag (2) expands and pushes the annular bag (1) to move radially in the cave (6) until the annular bag (1) is aligned with the guide borehole (8); S4: Grout is injected into the annular bag (1) through the grouting pipe (5), the grout fills the annular bag (1) and causes the annular bag (1) to expand outward, forming an annular protective wall on the outer periphery of the proposed pile foundation (7); S5: After the slurry reaches the design strength, the pile foundation drilling, mud wall protection, hole cleaning, lowering of the reinforcing cage and concrete pouring are carried out.

10. The adaptive treatment method for pile foundation construction in karst areas according to claim 9, characterized in that, When the proposed pile foundation (7) passes through multiple karst caves (6), an adaptive treatment bag for karst pile foundation construction is independently installed on the air injection pipe (4) and the grouting pipe (5) at the positions corresponding to each karst cave (6). The adaptive treatment bag for karst pile foundation construction is lowered together with the air injection pipe (4) and the grouting pipe (5) in the same installation process, so that each bag reaches the preset position of its corresponding karst cave (6) in sequence. Then, each positioning bag (2) is inflated and positioned and each annular bag (1) is grouted to achieve the treatment of multiple karst caves (6).

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