Pile foundation hole-forming steel casing construction system and construction method

Abstract

The application provides a pile foundation hole-forming steel casing construction system and a construction method, wherein the inner side wall of a guide arc plate is matched in size with the outer side wall of a steel casing; the upper arc plate positioning clamp of a casing alignment assembly is arranged on the top of the steel casing; the lower arc plate is matched in size with the inner side wall of the steel casing; the upper arc plate is fixedly connected with the lower arc plate through a vertical rod; two limiting arc plate structures are oppositely arranged on the steel casing; the two ends of an elastic member are respectively connected with the limiting arc plate structures; the two ends of a telescopic positioning member respectively pass through the vertical rod and outwardly extend to abut against the limiting arc plate structures; and the upper hoop body and the lower hoop body of an outer hoop assembly are respectively arranged on adjacent steel casings. The guide structure and the casing alignment assembly are arranged to realize the axial accurate positioning of the upper and lower steel casings, and the outer hoop assembly is arranged to realize the fixed connection of the upper and lower steel casings, so that the positioning and installation efficiency and the installation progress of the steel casing are greatly improved, and the piling efficiency and the piling quality of the pile foundation are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of pile foundation construction technology, specifically to a pile foundation hole-forming steel casing construction system and construction method. Background Technology

[0002] Highways are mostly located in hilly, mountainous, and karst areas, where the terrain, landforms, and hydrogeological conditions are complex and diverse. In particular, karst landforms are widely distributed in karst areas. However, the pile foundation construction plan usually needs to be determined based on the geological conditions of the construction area. The pile foundation construction of karst caves is unpredictable and dangerous, especially the pile foundation construction of multi-layered karst caves. Compared with traditional pile foundation construction, more attention needs to be paid to the stability of the steel casing and the bearing capacity of the pile foundation to ensure the overall bearing capacity of the highway or bridge and avoid problems such as settlement in the later stage.

[0003] In conventional karst areas, the construction of steel casings for pile foundations typically employs ultra-long steel casings, followed by concrete pouring to form the pile. However, if the steel casing length is insufficient or the connection is incomplete during the connection process, water inrush can easily occur. Other common problems include grout leakage, deviation, drill bit jamming, and pile breakage. Therefore, it is necessary to develop an improved steel casing construction method to address these challenges and improve the efficiency and quality of pile foundation construction. Summary of the Invention

[0004] The purpose of this invention is to provide a construction system and method for steel casing in pile foundation drilling, aiming to improve the efficiency and accuracy of steel casing connection.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The construction system for steel casing in pile foundation drilling includes a guide structure, casing alignment components, and outer hoop components;

[0007] The guiding structure includes a guide arc plate; the guide arc plate is positioned on the outside of the pile foundation; the inner side wall of the guide arc plate is sized to match the outer side wall of the steel casing, which is used to limit and guide the outer side of the steel casing.

[0008] The casing alignment assembly includes a limiting arc plate structure, an elastic element, and a retractable positioning element; the limiting arc plate structure includes an upper arc plate and a lower arc plate; the upper arc plate is positioned and locked onto the top of the steel casing; the lower arc plate is sized to match the inner wall of the steel casing; the upper arc plate is fixedly connected to the lower arc plate via a vertical rod; the two limiting arc plate structures are arranged opposite each other on the steel casing; both ends of the elastic element are connected to the limiting arc plate structure; both ends of the retractable positioning element pass through the vertical rod and extend outward to abut against the limiting arc plate structure.

[0009] The outer hoop assembly includes an upper hoop body and a lower hoop body; the upper hoop body and the lower hoop body are respectively disposed on adjacent steel casings, and the positioning connection between the upper hoop body and the lower hoop body is achieved by longitudinal steel plates.

[0010] As a further improvement of the present invention, the guide structure further includes a support frame; the support frame is positioned on the foundation on the side of the pile; the guide arc plate is positioned on the support frame.

[0011] As a further improvement of the present invention, the elastic element is a compression spring; the telescopic positioning element includes a through rod and a sleeve; the sleeve is detachably and fixedly connected to both ends of the through rod.

[0012] As a further improvement of the present invention, the sleeve is threaded to both ends of the through rod, and the extension and retraction of the telescopic positioning member is realized through the threaded connection of the sleeve on the through rod.

[0013] As a further improvement of the present invention, the compression spring is sleeved on the through rod, and the two axial ends of the compression spring respectively abut and limit the inner side of the vertical rod.

[0014] As a further improvement of the present invention, the through rod is also provided with scale lines along the axial direction, and the scale lines are arranged symmetrically at the center.

[0015] As a further improvement of the present invention, the outer hoop assembly is used to fix the bottom of the upper protective cylinder and the top of the lower protective cylinder; the back of the connecting clip is provided with a slot for inserting the hoop piece.

[0016] As a further improvement of the present invention, a radial L-shaped fixing strip is also provided; the fixing strip is L-shaped, with a vertical steel plate at one end, and a perforated steel plate is welded to its top after the steel casing is buried.

[0017] As a further improvement of the present invention, the lower part of the vertical rod is connected by a spring.

[0018] A method for constructing steel casings for pile foundation drilling includes the following steps:

[0019] S1. Construction preparation: Level the site, remove debris, prepare the materials needed for construction, and tie the steel cage.

[0020] S2. Measurement and positioning: Using a total station and steel tape, determine the center pile of the hole position, and set up guide arc plates around the pile position. Reinforce the protective pile with cement mortar and set up obvious marks.

[0021] S3. Installation of extra-long steel casing: Install in sections according to the thickness of the soft soil layer on the surface. The diameter of each steel casing section is 20cm larger than the designed pile diameter, and the length of a single section is 2m. The burial depth of the steel casing is preliminarily determined based on the geological survey data, and the number of steel casing sections required is calculated. The steel casing should be brought to the site in advance, and the steel casing is buried through the soft soil layer.

[0022] S4. Installing the lower steel casing: After determining the location of the lower casing, install a guide structure on the side of the designed location of the casing, and use a crane to lower the steel casing. The steel casing is lowered along the guide arc plate on one side, and the planar position deviation of the steel casing is controlled within 5cm and the tilt deviation is controlled within 1%.

[0023] S5. Lowering the steel casing segment: Install a casing alignment component inside the upper casing so that its upper arc plate is locked on the top of the upper casing. Lower the steel casing so that the upper casing slides down along the guide arc plate until it is aligned with the lower casing.

[0024] S6. Weld and install the connecting outer hoop device: Install semi-circular hoops at the bottom of the upper casing and the top of the lower casing respectively, and weld the two ends of the semi-circular hoops through the connecting clips and tighten them. After aligning and welding the two casings, fix the upper and lower connecting clips by welding longitudinal steel plates.

[0025] S7. Last section of steel casing: When burying a section of casing, ensure that the top surface of the casing is 0.3m above the ground and 2m above the groundwater level; weld a perforated steel plate to the top of the casing, and then use L-shaped soil nail fixing strips to fix it to the steel casing before installing soil nails to fix the steel casing.

[0026] S8. Drilling Rig Positioning: After the impact drilling rig is installed, accurately align the center of the drill bit with the center of the crosshair of the casing. Lift the drill bit and slowly place it into the steel casing. Start the mud pump and begin impacting after a certain amount of mud has been pumped into the hole.

[0027] S9. Drilling: When approaching karst formations, ensure sufficient mud is prepared before drilling to avoid sudden mud loss after drilling through the karst cave, which could lead to insufficient pressure in the borehole and cause collapse. Strengthen the geological inspection and verification of the borehole, and pay close attention to the working conditions of the drilling rig, the surrounding surface subsidence, and the water level changes in the casing.

[0028] S10. Final hole cleaning and cleaning: The hole is cleaned using the slurry replacement cleaning method; during the cleaning process, ensure that the water head in the hole is maintained to prevent hole collapse;

[0029] S11. Lowering the reinforcing cage: After cleaning the hole, lower the reinforcing cage and fix the top of the reinforcing cage with a fixing device;

[0030] S12. Concrete pouring: Concrete is poured using a truck-mounted pump.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This application achieves more precise axial positioning of the upper and lower steel casings by setting a guide structure and casing alignment components, and then uses an outer hoop component to achieve a fixed connection between the upper and lower steel casings, which greatly improves the positioning and installation efficiency and installation progress of the steel casings. The design is ingenious and also greatly improves the pile formation efficiency and pile formation quality of the pile foundation. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0034] Figure 1 This is a schematic diagram of the structure when the present invention is in use;

[0035] Figure 2 This is a schematic diagram of the guide structure of the present invention in use;

[0036] Figure 3 for Figure 1 A partial sectional view;

[0037] Figure 4 This is a schematic diagram of the sleeve alignment assembly structure of the present invention;

[0038] Figure 5 yes Figure 4 Schematic diagram of the upper arc plate installation structure;

[0039] Figure 6 This is a schematic diagram of the connected steel casing structure of the present invention;

[0040] Figure 7 yes Figure 6 Top view;

[0041] Figure 8 This is a flowchart of the present invention;

[0042] Explanation of the labels in the diagram:

[0043] 1. Guide structure; 11. Guide arc plate; 12. Support frame; 2. Casing alignment assembly; 21. Limiting arc plate structure; 211. Upper arc plate; 212. Lower arc plate; 213. Vertical rod; 214. Spring; 22. Compression spring; 23. Telescopic positioning component; 231. Through rod; 232. Sleeve; 3. Outer hoop assembly; 31. Upper hoop body; 32. Lower hoop body; 33. Longitudinal steel plate; 4. Steel casing; 41. Upper casing; 42. Lower casing; 5. Fixing strip. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Combined with appendix Figures 1 to 8 This invention provides a construction system and method for steel casing in pile foundation drilling, aiming to improve the efficiency and accuracy of steel casing connection.

[0046] Specifically, a construction system for steel casing in pile foundation drilling includes a guide structure 1, a casing alignment component 2, and an outer hoop component 3; the guide structure 1 includes a guide arc plate 11; the guide arc plate 11 is positioned on the outside of the pile foundation; the inner sidewall of the guide arc plate 11 is sized to match the outer sidewall of the steel casing 4, and is used to achieve outer edge limiting and guiding of the steel casing 4;

[0047] The sleeve alignment assembly 2 includes a limiting arc plate structure 21, an elastic element, and a retractable positioning element 23; the limiting arc plate structure 21 includes an upper arc plate 211 and a lower arc plate 212; the upper arc plate 211 is positioned and locked on the top of the steel sleeve 4; the lower arc plate 212 is matched with the inner wall size of the steel sleeve 4; the upper arc plate 211 is fixedly connected to the lower arc plate 212 by a vertical rod 213; the two limiting arc plate structures 21 are arranged opposite to each other on the steel sleeve 4; the two ends of the elastic element are respectively connected to the limiting arc plate structure 21; the two ends of the retractable positioning element 23 pass through the vertical rod 213 and extend outward to abut against the limiting arc plate structure 21;

[0048] The outer hoop assembly 3 includes an upper hoop body 31 and a lower hoop body 32; the upper hoop body 31 and the lower hoop body 32 are respectively provided on adjacent steel casings 4, and the upper hoop body 31 and the lower hoop body 32 are positioned and connected by longitudinal steel plates 33.

[0049] This application achieves more precise axial positioning of the upper and lower steel casings by setting a guide structure 1 and a casing alignment component 2, and then sets an outer hoop component 3 to achieve a fixed connection between the upper and lower steel casings, which greatly improves the positioning and installation efficiency and installation progress of the steel casing 4. The design is ingenious and at the same time greatly improves the pile formation efficiency and pile formation quality of the pile foundation.

[0050] Furthermore, the guide structure 1 also includes a support frame 12; the support frame is positioned on the foundation on the side of the pile; the guide arc plate 11 is positioned on the support frame 12.

[0051] Furthermore, the elastic element is a compression spring 22; the telescopic positioning element 23 includes a through rod 231 and a sleeve 232; the sleeve 232 is detachably and fixedly connected to both axial ends of the through rod 231.

[0052] Preferably, the sleeve 232 is threaded to both ends of the through rod 231, and the extension and retraction of the telescopic positioning member 23 is realized through the threaded connection of the sleeve 232 on the through rod 231.

[0053] Furthermore, the compression spring 22 is sleeved on the through rod 231, and the two axial ends of the compression spring 22 respectively abut against and limit the inner side of the vertical rod 213.

[0054] Furthermore, the through rod 231 is also provided with scale lines along the axial direction. The scale lines are centrally symmetrical. By adjusting the connection depth of the sleeves 232 at both ends, the sleeves 232 can be symmetrically arranged on the through rod 231, which is convenient and quick to adjust.

[0055] Furthermore, the outer hoop assembly 3 is used to fix the bottom of the upper protective cylinder 41 and the top of the lower protective cylinder 42. It consists of two semi-circular hoops that hold the steel protective cylinder 4 together, and the ends of the hoops are inserted into connecting clips and then welded. The back of the connecting clips is provided with a slot for inserting the hoop pieces. After the upper and lower protective cylinders 42 are joined and welded together, the upper and lower hoops are welded into a whole by longitudinal steel plates 33.

[0056] It should be noted that when installing the telescopic positioning component 23, after unscrewing the sleeve 232 from one end of the through rod 231, the through rod 231 is passed sequentially through the two symmetrically arranged vertical rods 213, and then the unscrewed sleeve 232 is installed on one end of the through rod 231; when it is necessary to adjust the length of the entire telescopic positioning component 23, it is only necessary to screw the sleeve 232 to achieve the extension and retraction of its overall length;

[0057] When the upper arc plate 211 is clamped onto the upper steel casing 4, the two upper arc plates 211 are positioned relative to each other by the spring 214. By adjusting the through rod 231 and the sleeve 232, the upper arc plates 211 on both sides are pressed tightly against the steel casing 4. The two upper arc plates 211 are tightly embedded in the steel casing 4, and the lower arc plate 212, which is fixedly connected to the lower part of the vertical rod 213, is positioned inside the lower casing 42. At this time, by adjusting the connection depth between the sleeve 232 and the through rod 231, the vertical rod 213, which is fixedly connected to the upper arc plate 211, is axially symmetrically positioned.

[0058] After the upper and lower casings 42 are aligned and connected, the outer hoop devices are respectively attached to the bottom of the upper casing 41 and the top of the lower casing 42 and clamped by welding with connecting clips; after the upper and lower casings 42 are welded, the outer hoop devices are fixed by welding with longitudinal steel plates 33.

[0059] It also has radial L-shaped fixing strips 5; the fixing strips 5 are L-shaped, with a vertical steel plate at one end. After the steel casing 4 is buried, a perforated steel plate is welded to its top. The steel casing 4 is fixed by bolts passing through the bolt holes of the two steel plates. The other end of the L-shaped fixing strips 5 has soil nail holes. The L-shaped fixing strips 5 are fixed to the foundation by driving in soil nails, thereby fixing the steel casing.

[0060] Furthermore, the lower part of the vertical rod 213 is connected by a spring 214, which enables the upper and lower arc plates 212 of the entire telescopic positioning component to be elastically connected mainly by compression springs 22 and springs 214 when the lower arc plate 212 is placed inside the steel casing 4. This avoids hard contact with the components during placement, thus preventing damage to the components and avoiding inaccurate positioning. The design is ingenious, practical, convenient and flexible.

[0061] A method for constructing steel casings for pile foundation drilling includes the following steps:

[0062] S1. Construction preparation: Level the site, remove debris, prepare the materials needed for construction, and tie the steel cage.

[0063] S2. Measurement and positioning: Using a total station and steel tape, determine the center pile of the hole, and set up guide arc plates 112 around the pile position. Reinforce the protective pile with cement mortar and set up obvious markers.

[0064] S3, Extra-long steel casing 4: Installed in sections according to the thickness of the soft soil layer on the surface. The diameter of each section of steel casing 4 is 20cm larger than the designed pile diameter, and the length of a single section is 2m. The burial depth of steel casing 4 is preliminarily determined based on geological survey data, and the number of steel casing 4 sections required is calculated. Steel casing 4 should be brought to the site in advance and buried through the soft soil layer.

[0065] S4. Installing the lower steel casing 4: After determining the installation position of the lower casing 42, install the guide structure 1 on the side of the designed position of the casing, and use a crane to lower the steel casing 4. The steel casing 4 is lowered along the guide arc plate 11 on one side, and the planar position deviation of the steel casing 4 is controlled within 5cm and the tilt deviation is controlled within 1%.

[0066] S5. Lowering the steel casing 4: Set the casing alignment component 2 inside the upper casing 41 so that its upper arc plate 211 is stuck on the top of the upper casing 41. Lower the steel casing 4 so that the upper casing 41 slides down along the guide arc plate 11 until it is aligned with the lower casing 42.

[0067] S6. Weld and install the connecting outer hoop device: Install semi-circular hoops at the bottom of the upper casing 41 and the top of the lower casing 42 respectively, and weld the two ends of the semi-circular hoops through the connecting clips and tighten them. After aligning and welding the two casings, weld the upper and lower connecting clips through the longitudinal steel plate 33 to fix them.

[0068] S7, Last section of steel casing 4: When burying a section of casing, ensure that the top surface of the casing is 0.3m above the ground and the groundwater level is 2m above the ground; weld a perforated steel plate to the top of the casing, and then use L-shaped soil nail fixing strips to fix it to the steel casing 4 before installing soil nails to fix the steel casing 4.

[0069] S8. Drilling Rig Positioning: After the impact drilling rig is installed, accurately align the center of the drill bit with the center of the crosshair of the casing. Lift the drill bit and slowly place it into the steel casing 4. Start the mud pump and begin impacting after a certain amount of mud has been pumped into the hole.

[0070] S9. Drilling: When approaching karst formations, ensure sufficient mud is prepared before drilling to avoid sudden mud loss after drilling through the karst cave, which could lead to insufficient pressure in the borehole and cause collapse. Strengthen the geological inspection and verification of the borehole, and pay close attention to the working conditions of the drilling rig, the surrounding surface subsidence, and the water level changes in the casing.

[0071] S10. Final hole cleaning and cleaning: The hole is cleaned using the slurry replacement cleaning method; during the cleaning process, ensure that the water head in the hole is maintained to prevent hole collapse;

[0072] S11. Lowering the reinforcing cage: After cleaning the hole, lower the reinforcing cage and fix the top of the reinforcing cage with a fixing device;

[0073] S12. Concrete pouring: Concrete is poured using a truck-mounted pump.

[0074] It should be noted that the parts not described in detail in this invention are well-known technologies in the field, or can be directly purchased from the market. Those skilled in the art can obtain them without creative effort. The specific connection methods have extremely wide applications in the field or in daily life, and will not be described in detail here.

[0075] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0076] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0077] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0078] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0079] 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.

[0080] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A construction method based on a pile foundation drilling steel casing construction system, wherein the pile foundation drilling steel casing construction system includes a guide structure, a casing alignment assembly, and an outer hoop assembly; The guiding structure includes a guide arc plate; the guide arc plate is positioned on the outside of the pile foundation; the inner side wall of the guide arc plate is sized to match the outer side wall of the steel casing, which is used to limit and guide the outer side of the steel casing. The casing alignment assembly includes a limiting arc plate structure, an elastic element, and a retractable positioning element; the limiting arc plate structure includes an upper arc plate and a lower arc plate; the upper arc plate is positioned and locked onto the top of the steel casing; the lower arc plate is sized to match the inner wall of the steel casing; the upper arc plate is fixedly connected to the lower arc plate via a vertical rod; the two limiting arc plate structures are arranged opposite each other on the steel casing; both ends of the elastic element are connected to the limiting arc plate structure; both ends of the retractable positioning element pass through the vertical rod and extend outward to abut against the limiting arc plate structure. The lower part of the vertical rod is connected by a spring. The outer hoop assembly includes an upper hoop body and a lower hoop body. The upper hoop body and the lower hoop body are respectively set on adjacent steel casings. The steel casing is clamped by two semi-circular hoops, and the ends of the hoops are inserted into connecting clips and then welded. The positioning connection of the upper hoop body and the lower hoop body is achieved by longitudinal steel plates. Radial L-shaped fixing strips are also provided. The construction method includes the following steps: S1. Construction preparation: Level the site, remove debris, prepare the materials needed for construction, and tie the steel cage. S2. Measurement and positioning: Using a total station and steel tape, determine the center pile of the hole position, and set up guide arc plates around the pile position. Reinforce the protective pile with cement mortar and set up obvious marks. S3. Installation of extra-long steel casing: Install in sections according to the thickness of the soft soil layer on the surface. The diameter of each steel casing section is 20cm larger than the designed pile diameter, and the length of a single section is 2m. The burial depth of the steel casing is preliminarily determined based on the geological survey data, and the number of steel casing sections required is calculated. The steel casing should be brought to the site in advance, and the steel casing is buried through the soft soil layer. S4. Installing the lower steel casing: After determining the location of the lower casing, install a guide structure on the side of the designed location of the casing, and use a crane to lower the steel casing. The steel casing is lowered along the guide arc plate on one side, and the planar position deviation of the steel casing is controlled within 5cm and the tilt deviation is controlled within 1%. S5. Lowering the steel casing segment: Install a casing alignment component inside the upper casing so that its upper arc plate is locked on the top of the upper casing. Lower the steel casing so that the upper casing slides down along the guide arc plate until it is aligned with the lower casing. S6. Weld and install the connecting outer hoop assembly: Install semi-circular hoops at the bottom of the upper casing and the top of the lower casing respectively, and weld the two ends of the semi-circular hoops through the connecting clips and tighten them. After aligning and welding the two casings, fix the upper and lower connecting clips by welding longitudinal steel plates. S7. Last section of steel casing: When burying a section of casing, ensure that the top surface of the casing is 0.3m above the ground and 2m above the groundwater level; weld a perforated steel plate to the top of the casing, and then use L-shaped fixing strips to fix it to the steel casing before installing soil nails to fix the steel casing. S8. Drilling Rig Positioning: After the impact drilling rig is installed, accurately align the center of the drill bit with the center of the crosshair of the casing. Lift the drill bit and slowly place it into the steel casing. Start the mud pump and begin impacting after a certain amount of mud has been pumped into the hole. S9. Drilling: When approaching karst formations, ensure sufficient mud is prepared before drilling to avoid sudden mud loss after drilling through the karst cave, which could lead to insufficient pressure in the borehole and cause collapse. Strengthen the geological inspection and verification of the borehole, and pay close attention to the working conditions of the drilling rig, the surrounding surface subsidence, and the water level changes in the casing. S10. Final hole cleaning and cleaning: The hole is cleaned using the slurry replacement cleaning method; during the cleaning process, ensure that the water head in the hole is maintained to prevent hole collapse; S11. Lowering the reinforcing cage: After cleaning the hole, lower the reinforcing cage and use a fixing device to fix the top of the reinforcing cage. S12. Concrete pouring: Concrete is poured using a truck-mounted pump. The guide structure also includes a support frame; the support frame is positioned on the foundation on the side of the pile; the guide arc plate is positioned on the support frame; The elastic element is a compression spring; the telescopic positioning element includes a through rod and a sleeve; the sleeve is detachably and fixedly connected to both ends of the through rod. The sleeve is threaded to both ends of the through rod, and the extension and retraction of the telescopic positioning component is realized through the threaded connection of the sleeve on the through rod. The compression spring is sleeved on the through rod, and the two axial ends of the compression spring respectively abut against and limit the inner side of the vertical rod; The through rod is also provided with scale lines along the axial direction, and the scale lines are arranged symmetrically at the center.

2. The construction method based on the steel casing construction system for pile foundation drilling according to claim 1, characterized in that: The fixing strip is L-shaped, with a vertical steel plate at one end. After the steel casing is buried, a perforated steel plate is welded to its top.

3. The construction method based on the steel casing construction system for pile foundation drilling according to claim 1, characterized in that: The fixing strip is L-shaped, with a vertical steel plate at one end. After the steel casing is buried, a perforated steel plate is welded to its top.

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