Long pile casing rotary drilling hole-forming pile foundation for water-rich and water-permeable stratum and construction method of long pile casing rotary drilling hole-forming pile foundation

Abstract

The invention relates to a long pile casing rotary drilling hole-forming pile foundation for a water-rich and water-permeable stratum and a construction method. The long pile casing rotary drilling hole-forming pile foundation comprises a long pile casing hoop auxiliary welding system, an anti-shrinkage special-shaped drill bit system and a reinforcement cage suspension pre-assembly system. The long pile casing hoop auxiliary welding system has the beneficial effects that the sectional pile casings are firstly positioned and fastened by the long pile casing hoop auxiliary welding system and then are subjected to auxiliary welding, so that high-precision rapid sectional lowering of the ultra-large-diameter long pile casings is realized; the hole shrinkage prevention special-shaped drill bit system is used for rotary excavating and hole forming, and by arranging a pressure relief channel and a pressure relief strip, local hole shrinkage and even hole collapse under the water-rich and water-permeable stratum condition are avoided; according to the reinforcement cage suspension pre-assembly system, the reinforcement cage is vertically pre-assembled and formed by forming a special lengthening hole, and then the reinforcement cage is integrally hoisted and transversely moved into the hole at a time, so that reinforcement cage lengthening and drilling operations are synchronously carried out, and the time of pile hole operation occupied by reinforcement cage lengthening is saved; and a single lengthening hole can meet the lengthening and hoisting requirements of a plurality of pile foundation reinforcement cages at the same time.

Description

Technical Field

[0001] The invention belongs to the field of pile foundation construction, and in particular relates to a pile foundation with a long casing and a rotary drilling hole in a water-rich and permeable stratum and a construction method. Background Art

[0002] In modern construction projects, pile foundations are an important form of foundation and are widely used in the construction of various types of buildings, bridges and other infrastructure. With the acceleration of urbanization and the continuous emergence of large-scale projects, the geological conditions faced by engineering construction are becoming more complex and diverse. Among them, water-rich and permeable strata have brought many severe challenges to pile foundation construction.

[0003] The traditional rotary drilling process has the advantages of high construction efficiency and good drilling quality in general strata. However, its limitations become apparent when facing water-rich and permeable strata. The high water content and strong permeability of water-rich and permeable strata make it very easy for the hole wall to collapse during the drilling process. The rapid flow of groundwater will continuously scour the hole wall, destroy the stability of the hole wall soil, cause the hole wall soil to lose its original structural strength and collapse, and seriously affect the drilling quality and construction progress.

[0004] At the same time, due to the strong permeability of the formation, the mud wall protection effect is difficult to maintain effectively. In conventional rotary drilling, mud plays a key role in wall protection and slag carrying. However, in water-rich and permeable formations, the water in the mud will quickly lose to the surrounding formations, causing the mud performance to deteriorate sharply, and it will be impossible to form an effective wall protection mud skin, and it will be difficult to ensure the stability of the hole wall. In addition, the large loss of mud will also cause material waste and increase construction costs.

[0005] Moreover, under such geological conditions, the quality of the pile body after the traditional construction method is difficult to guarantee. The hole wall collapse and mud performance problems may cause the pile body to have defects such as shrinkage and mud inclusion, reducing the bearing capacity of the pile body and affecting the safety and stability of the entire engineering structure.

[0006] In summary, the existing rotary drilling technology has many shortcomings in the construction of water-rich and permeable strata. A new pile foundation and construction method are urgently needed to solve these problems, so as to ensure the smooth progress of pile foundation construction under complex geological conditions and improve the quality and safety of the project. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a long casing rotary bored pile foundation in a water-rich and permeable stratum and a construction method.

[0008] The long casing rotary drilling pile foundation in water-rich and permeable strata comprises a long casing hoop auxiliary welding system, an anti-shrinkage special-shaped drill bit system and a steel cage suspension pre-assembly system; the long casing comprises an upper casing and a lower casing; the long casing hoop auxiliary welding system comprises an upper hoop unit ring and a lower hoop unit ring; the upper hoop unit ring is sleeved at the bottom of the upper casing, and the lower hoop unit ring is sleeved at the top of the lower casing; the gap between the upper hoop unit ring and the lower hoop unit ring is a casing welding groove; the anti-shrinkage special-shaped drill bit system is vertically arranged in the long casing The anti-shrinkage special-shaped drill bit system includes an arc-shaped drill barrel; a pressure relief channel is provided on the side wall of the arc-shaped drill barrel; cutting teeth are provided on the bottom of the arc-shaped drill barrel; the steel cage suspension pre-assembly system includes an extension hole and a steel cage anti-sinking device; the extension hole is inserted into the ground, and the side wall exposed to the ground is penetrated by a through hole; the bottom of the steel cage anti-sinking device is fixed to the ground around the extension hole, and the end is inserted into the through hole; a steel cage positioning guide frame is arranged above the extension hole, and a steel cage is penetrated inside the steel cage positioning guide frame; the crane is parked on the ground in the long casing construction area.

[0009] Preferably, the upper hoop unit ring and the lower hoop unit ring are of symmetrical structure in the upper and lower parts; the side walls at both ends of the upper hoop unit ring and the lower hoop unit ring are connected with a transverse connection system, the transverse connection system includes a transverse fixing plate and an angle plate, the transverse fixing plate is connected to both ends of the upper hoop unit ring and the lower hoop unit ring, and bolts are passed through and fixed on the sides of adjacent transverse fixing plates; a vertical connection system is provided on the middle side walls of the upper hoop unit ring and the lower hoop unit ring; the vertical connection system includes a vertical fixing plate and an ear plate; the vertical fixing plate is of L-shaped structure and is fixed to the side walls of the upper hoop unit ring and the lower hoop unit ring, and adjacent vertical fixing plates are fitted through the ear plates; a vertical bubble level and a transverse bubble level are provided on the side walls of the ear plates.

[0010] Preferably, the pressure relief channel is circumferentially distributed on the side wall of the arc-shaped drill barrel and presents an arc-shaped groove structure, and a pressure relief strip is provided on the inner wall of the pressure relief channel; a gauge cutter is provided on the side wall of the arc-shaped drill barrel; the cutting teeth include spiral blades and cutting teeth; a rotating shaft is provided at the center of the cutting teeth, one end of the spiral blade is fixed on the rotating shaft, and the spiral blades are distributed circumferentially around the rotating shaft; a central shaft is fixed through the center of the arc-shaped drill barrel, and the top of the central shaft is higher than the arc-shaped drill barrel.

[0011] Preferably, the extension hole is a full casing structure, the depth of which is consistent with the length of the steel cage, and the inner diameter is larger than the outer diameter of the steel cage; the extension hole is higher than the ground surface, and a through hole is provided on the top; the steel cage anti-sinking device includes a movable limit rod and a support; the bottom of the support is fixed to the ground around the extension hole; the support is penetrated by a movable limit rod, and the end of the movable limit rod is inserted into the through hole; the inner diameter of the through hole is larger than the outer diameter of the movable limit rod.

[0012] Preferably, the steel cage positioning guide frame includes a steel cage limiting pipe; support rods are provided at the four corners of the steel cage positioning guide frame, and the bottom of the support rods is fixed to the ground; connecting rods are connected between the support rods; the steel cage limiting pipe is located directly above the extension hole; the side wall of the steel cage limiting pipe is connected to a fixing rod, and the steel cage limiting pipe is arranged on the upper part of the supporting rod through the fixing rod. The center positions of the steel cage limiting pipe and the extension hole are located in the same straight line.

[0013] The method for rotary drilling pile foundation with long casing in water-rich and permeable stratum comprises the following steps:

[0014] Step 1: construct the extension hole near the designed pile foundation area;

[0015] Step 2: Press the first section of the lower casing into the ground at the designed pile foundation point, hoist the upper casing into place, install the long casing hoop auxiliary welding system, weld the lower casing and the upper casing; weld the casing in sections in sequence until the long casing is completed;

[0016] Step 3: Use the anti-shrinkage special-shaped drill bit system to perform rotary drilling in the long casing until a hole is formed; at the same time, use the steel cage suspension pre-assembly system to pre-assemble the steel cage into sections at the extension hole;

[0017] Step 4: Use a crane to hoist and transversely move the steel cage in the extension hole as a whole at one time; use a steel cage positioning guide frame to guide the steel cage, so that the crane lowers the steel cage to the designated position;

[0018] Step 5: Pour concrete, and after the concrete has initially set, remove the long casing.

[0019] Preferably, vertical fixing plates are fixed to the side walls of the upper hoop unit ring and the lower hoop unit ring, and adjacent vertical fixing plates are fitted together by ear plates; vertical bubble levels and horizontal bubble levels are provided on the side walls of the ear plates; in the step two, when installing the long casing hoop auxiliary welding system, the upper hoop unit ring and the lower hoop unit ring are adjusted and positioned by the vertical bubble level and the horizontal bubble level to ensure the installation accuracy of the long casing.

[0020] Preferably, in the step 2, the upper casing and the lower casing are welded through the reserved space of the casing welding groove to form a casing weld; when welding the casing in sections, it is only necessary to loosen the bolts of the long casing clamp auxiliary welding system in situ, and after the welded casing continues to be pressed into the formation and the casing to be installed is hoisted into place, tighten the bolts to complete the welding of the next section.

[0021] Preferably, in step three, the steel cage anti-sinking device includes a movable limiting rod and a support; the bottom of the support is fixed to the ground around the extension hole; the support is penetrated by a movable limiting rod, and the end of the movable limiting rod is inserted into the through hole; when the steel cage is pre-assembled in sections, the steel cage is temporarily supported and positioned by passing the movable limiting rod through the through hole and the steel cage, and then the upper and lower sections of the steel cage are connected.

[0022] Preferably, in the step three, the anti-shrinkage special-shaped drill bit system includes an arc-shaped drill barrel; a pressure relief channel is provided on the side wall of the arc-shaped drill barrel; a cutting tooth is provided at the bottom of the arc-shaped drill barrel; the cutting tooth includes a spiral blade and a cutting tooth; a rotating shaft is provided at the center of the cutting tooth, one end of the spiral blade is fixed on the rotating shaft, and the spiral blades are distributed around the circumference of the rotating shaft; a central shaft is fixed through the center of the arc-shaped drill barrel, and the top of the central shaft is higher than the arc-shaped drill barrel; when rotary drilling is carried out using the anti-shrinkage special-shaped drill bit system in a long casing, the rotary drilling rig is started, and the central shaft is accurately connected to the power output shaft of the drilling rig; as the drill bit drills, the pressure relief channel releases the water pressure in the formation in time; the spiral blade and the cutting tooth at the bottom of the cutting tooth work together, the cutting tooth crushes the rock and soil, and the spiral blade transports the cut soil to the outside of the hole.

[0023] The beneficial effects of the present invention are:

[0024] 1) The present invention utilizes a long casing hoop auxiliary welding system to respectively sleeve the upper hoop unit ring and the lower hoop unit ring on the corresponding casing, stabilize them with the help of the horizontal connection system and the vertical connection system, accurately position the segmented casing, and then weld the casing using the casing welding groove; through this system, the segmented casing is first positioned and tightened, and then assisted in welding, thereby achieving high-precision and rapid segmented lowering of ultra-large diameter long casings, reducing positioning and rework, improving construction efficiency, and saving costs.

[0025] 2) When the present invention uses the anti-shrinkage special-shaped drill bit system to drill a hole, the pressure relief channel and pressure relief strip in the drill bit can release the water pressure in time in the water-rich and permeable formation, balance the pressure difference inside and outside the hole, prevent the suction negative pressure caused by the blockage of the flow gap, avoid local shrinkage and hole collapse, and ensure the quality and safety of the hole.

[0026] 3) The present invention uses a special extension hole, and uses a steel cage suspension pre-assembly system to assemble the steel cage at the extension hole, and after pre-assembly, the entire steel cage is hoisted into the pile hole. This method allows the steel cage to be extended synchronously with the drilling, saving pile hole operation time, and a single extension hole can serve multiple pile foundations, improving site utilization and construction progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the connection diagram of the upper and lower hoop unit rings in the long casing hoop auxiliary welding system;

[0028] Figure 2 It is a schematic diagram of connecting casings using a long casing hoop auxiliary welding system;

[0029] Figure 3 This is a partial view of the ear plate in the long casing hoop auxiliary welding system;

[0030] Figure 4 This is a top view of the anti-shrinkage special-shaped drill bit system;

[0031] Figure 5 This is the axial view of the anti-shrinkage special-shaped drill bit system;

[0032] Figure 6 This is the bottom view of the anti-shrinkage special-shaped drill bit system;

[0033] Figure 7 It is a top view of the steel cage suspension pre-assembly system;

[0034] Figure 8 It is a schematic diagram of connecting steel cages in sections using a steel cage suspension pre-assembly system;

[0035] Fig. 9 It is a demonstration diagram of the simultaneous operation of extending the steel cage and drilling holes.

[0036] Explanation of the accompanying drawings: upper casing 1-1, lower casing 1-2, upper clamp unit ring 2-1, lower clamp unit ring 2-2, horizontal fixing plate 3, angle plate 4, vertical fixing plate 5, ear plate 6, vertical bubble level 6-1, horizontal bubble level 6-2, center axis 7, pressure relief channel 8, arc drill tube 9, cutting teeth 10, pressure relief strip 11, gauge knife 12, spiral blade 13, blade tooth 14, crane 15, extension hole 16, through hole 16-1, steel cage positioning guide frame 17, steel cage limiting tube 17-1, fixing rod 17-2, connecting rod 17-3, support rod 17-4, steel cage 18, steel cage anti-sinking device 19, movable limiting rod 19-1, support 19-2, bolt 20, casing welding groove 21, casing weld 22. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0038] Embodiment 1

[0039] As an example, Figures 1 to 9As shown, a long casing rotary drilling pile foundation for water-rich and permeable strata is proposed, including a long casing hoop auxiliary welding system, an anti-shrinkage special-shaped drill bit system and a steel cage suspension pre-assembly system; the long casing includes an upper casing 1-1 and a lower casing 1-2; the long casing hoop auxiliary welding system includes an upper hoop unit ring 2-1 and a lower hoop unit ring 2-2; the upper hoop unit ring 2-1 is sleeved on the bottom of the upper casing 1-1, and the lower hoop unit ring 2-2 is sleeved on the top of the lower casing 1-2; the gap between the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 is a casing welding groove 21; the anti-shrinkage special-shaped drill bit system is vertically arranged on the long casing Inside the tube, the anti-shrinkage special-shaped drill bit system includes an arc-shaped drill tube 9; a pressure relief channel 8 is provided on the side wall of the arc-shaped drill tube 9; a cutting tooth 10 is provided at the bottom of the arc-shaped drill tube 9; the steel cage suspension pre-assembly system includes an extension hole 16 and a steel cage anti-sinking device 19; the extension hole 16 is inserted into the ground, and the side wall exposed to the ground is penetrated by a through hole 16-1; the bottom of the steel cage anti-sinking device 19 is fixed to the ground around the extension hole 16, and the end is inserted into the through hole 16-1; a steel cage positioning guide frame 17 is arranged above the extension hole 16, and a steel cage 18 is penetrated inside the steel cage positioning guide frame 17; the crane 15 is parked on the ground in the long casing construction area.

[0040] like Figures 1 to 3 As shown, the long casing hoop auxiliary welding system mainly includes an upper casing 1-1, a lower casing 1-2, an upper hoop unit ring 2-1 and a lower hoop unit ring 2-2. Among them, the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are symmetrical structures; the upper hoop unit ring 2-1 is arranged around the bottom of the upper casing 1-1, and the lower hoop unit ring 2-2 is arranged around the top of the lower casing 1-2.

[0041] The side walls at both ends of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are connected with a transverse connection system, and the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are each connected to form a complete ring through a specific transverse connection system. The transverse connection system is composed of a transverse fixing plate 3 and an angle plate 4. This combination ensures that the hoop unit ring is firmly connected in the transverse direction. The upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are fixed and formed by a vertical connection system. The vertical connection system includes a vertical fixing plate 5 and an ear plate 6, and a reliable connection between the upper and lower hoop unit rings is achieved through the vertical connection system.

[0042] The vertical fixing plate 5 is an L-shaped structure and is fixed to the side walls of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2. Adjacent vertical fixing plates 5 are fitted together through ear plates 6; the side walls of the ear plates 6 are provided with a vertical bubble level 6-1 and a horizontal bubble level 6-2.

[0043] The gap between the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 naturally forms a casing welding groove 21, which provides a convenient and standardized space for the welding operation of the upper casing 1-1 and the lower casing 1-2, helps to improve the casing welding quality, and further ensures the stability and reliability of the long casing in the pile foundation construction in water-rich and permeable strata.

[0044] Embodiment 2

[0045] As another embodiment, this embodiment 2 proposes, based on the embodiment 1, a more specific long casing rotary drilling pile foundation in water-rich and permeable formations, comprising:

[0046] like Figures 4 to 6 As shown, the anti-shrinkage special-shaped drill bit system is mainly composed of a central axis 7, a pressure relief channel 8, an arc-shaped drill tube 9 and cutting teeth 10. The central axis 7 is precisely set at the center of the arc-shaped drill tube 9, serving as the core support structure of the entire drill bit system, providing a stable rotation axis for the drill bit during the drilling process.

[0047] The pressure relief channel 8 is arranged on the side wall of the arc-shaped drill tube 9, presenting a unique arc-shaped groove structure, and three of them can be arranged axially symmetrically. In water-rich and permeable formations, the pressure relief channel 8 plays a vital role. As the drill bit continues to drill, the water pressure in the formation will continue to accumulate, and the pressure relief channel 8 can release the accumulated water pressure in time, effectively balancing the pressure difference between the inside and outside of the hole, avoiding the extrusion deformation of the hole wall soil due to pressure imbalance, and thus preventing the occurrence of shrinkage.

[0048] The cutting teeth 10 are arranged at the bottom of the arc-shaped drill barrel 9, and include spiral blades 13 and blade teeth 14. During the rotation of the drill bit, the spiral blades 13 can transport the cut soil to the outside of the hole in time to avoid soil accumulation in the hole and affect the drilling efficiency; the spiral structure can produce a certain compaction effect on the soil of the hole wall while transporting the soil, thereby enhancing the stability of the hole wall. The blade teeth 14 can efficiently crush the rock and soil in the stratum, improve the drilling efficiency, and ensure that the drill bit can drill smoothly in complex strata. Through this specially designed cutting tooth 10 structure, working in coordination with the arc-shaped drill barrel 9 and other components, the construction performance of the anti-shrinkage special-shaped drill bit system in water-rich and permeable strata is greatly improved.

[0049] like Figures 7 to 9 As shown, the steel cage suspension pre-assembly system is mainly composed of an extension hole 16, a steel cage positioning guide frame 17, a steel cage 18 and a steel cage anti-sinking device 19.

[0050] The steel cage positioning guide frame 17 comprises a steel cage limiting pipe 17-1, a fixing rod 17-2, a connecting rod 17-3 and a supporting rod 17-4. Support rods 17-4 are provided at the four corners of the steel cage positioning guide frame 17, and the bottom of the supporting rods 17-4 is fixed to the ground; connecting rods 17-3 are connected between the supporting rods 17-4; the steel cage limiting pipe 17-1 is located directly above the extension hole 16; the side wall of the steel cage limiting pipe 17-1 is connected to the fixing rod 17-2, and the steel cage limiting pipe 17-1 is arranged on the upper part of the supporting rod 17-4 through the fixing rod 17-2. The center positions of the steel cage limiting pipe 17-1 and the extension hole 16 are located in the same straight line.

[0051] The steel cage limiting tube 17-1 is used to accurately control the position of the steel cage 18, ensuring its verticality and accuracy during pre-assembly and subsequent lowering, and avoiding the deviation of the steel cage. The fixing rod 17-2 plays a role in stabilizing the overall structure of the guide frame and enhancing its stability in the complex environment of the construction site. The connecting rod 17-3 effectively connects the various components to form a whole, and synergistically plays the positioning and guiding function of the guide frame. The support rod 17-4 provides additional support for the guide frame, enabling it to better withstand the weight of the steel cage and various external forces during the construction process.

[0052] The steel cage anti-sinking device 19 is composed of a movable limiting rod 19-1 and a support 19-2. The bottom of the support 19-2 is fixed to the ground around the extension hole 16; the support 19-2 is penetrated by the movable limiting rod 19-1, and the end of the movable limiting rod 19-1 is inserted into the through hole 16-1; the inner diameter of the through hole 16-1 is larger than the outer diameter of the movable limiting rod 19-1.

[0053] During the construction process, when the steel cage is lowered to the designated position, the movable limit rod 19-1 can be flexibly adjusted according to the actual situation. By cooperating with the support 19-2, it can effectively prevent the steel cage from sinking due to the impact of water flow in the hole, soil compression and other factors, ensuring that the steel cage is always in the position required by the design. The extension hole 16 provides convenient conditions for the extension of the steel cage. Through the coordinated work of various components, this steel cage suspension pre-assembly system greatly optimizes the installation process of the steel cage in the construction of long casing rotary bored pile foundation in water-rich and permeable strata, and improves the construction quality and efficiency.

[0054] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0055] Embodiment 3

[0056] As another embodiment, this embodiment 3 proposes, on the basis of the embodiment 2, a method for rotary drilling a pile foundation with a long casing in a water-rich and permeable stratum, comprising the following steps:

[0057] Step 1: construct the extension hole 16 near the designed pile foundation area; according to the pile foundation design drawings, with the help of high-precision measuring instruments, accurately determine the construction position of the extension hole 16 near the designed pile foundation area and make obvious marks.

[0058] A rotary drilling rig or an anti-shrinkage special-shaped drill bit system is used to drill the extended hole 16 in accordance with the design aperture and depth requirements of the maximum steel cage size, and the full casing is lowered and installed to form the extended hole 16. During the construction process, close attention is paid to the stability of the hole wall, and the mud performance can be adjusted in time according to the formation conditions to ensure the quality of the hole and prevent problems such as hole wall collapse.

[0059] Step 2: Press the first section of the lower casing 1-2 into the ground at the designed pile foundation point, hoist the upper casing 1-1 into place, install the long casing clamp auxiliary welding system, weld the lower casing 1-2 and the upper casing 1-1; weld the casing in sections in sequence until the long casing is completed.

[0060] like Figures 1 to 3 As shown, the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are symmetrical structures in the upper and lower parts; the side walls at both ends of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are connected with a transverse connection system, and the transverse connection system includes a transverse fixing plate 3 and an angle plate 4. The transverse fixing plate 3 is connected to both ends of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2, and bolts 20 are passed through and fixed on the sides of adjacent transverse fixing plates 3; a vertical connection system is provided on the middle side walls of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2; the vertical connection system includes a vertical fixing plate 5 and an ear plate 6; the vertical fixing plate 5 is an L-shaped structure and is fixed to the side walls of the upper hoop unit ring 2-1 and the lower hoop unit ring 2-2, and adjacent vertical fixing plates 5 are fitted together by ear plates 6; a vertical bubble level 6-1 and a transverse bubble level 6-2 are provided on the side walls of the ear plates 6.

[0061] At the designed pile foundation point, use large hydraulic pile driver or vibrating pile driver and other equipment to slowly press the first section of lower casing 1-2 into the formation. During the pressing process, the verticality of the lower casing needs to be monitored in real time to ensure that its deviation is controlled within the design allowable range. The upper hoop unit ring 2-1 and the lower hoop unit ring 2-2 are adjusted and positioned by the vertical bubble level 6-1 and the horizontal bubble level 6-2 to ensure the installation accuracy of the long casing; verticality observation and adjustment can also be performed by setting a vertical observation instrument such as a theodolite or a total station on the top of the casing.

[0062] A large crane is used to accurately hoist the upper casing 1-1 above the lower casing 1-2 and place it in place. The long casing hoop auxiliary welding system is quickly installed, the upper hoop unit ring 2-1 is wrapped around the bottom of the upper casing 1-1, the lower hoop unit ring 2-2 is wrapped around the top of the lower casing 1-2, and the hoop unit rings are connected into a ring through the horizontal connection system, and then the upper and lower hoop unit rings are fixed and formed using the vertical connection system to form a casing welding groove 21.

[0063] In the casing welding groove 21, the welding workers use the welding process and materials required by the design to weld the lower casing 1-2 and the upper casing 1-1. During the welding process, strictly follow the welding quality standards, control the welding current, voltage and welding speed and other parameters, and ensure that the weld is full and firm, without defects such as false welds and leaks. After each section of the casing is welded, the weld needs to be visually inspected and non-destructively tested. Only after passing the inspection can the next section of the casing be installed and welded. The casing is welded in sections in sequence until the long casing is completed. After the welding is completed, the verticality of the long casing is checked again to ensure that the overall verticality meets the design requirements.

[0064] After the first section of the lower casing 1-2 is connected to the upper casing 1-1, it is only necessary to loosen the bolts 20 of the auxiliary welding system of the long casing clamp in situ, continue to press the above two sections of welded casing into the formation, and tighten the bolts 20 to complete the welding of the new section of casing after the new section of casing is hoisted in place. Repeat the above operation until the long casing is completely completed.

[0065] Step 3: Use an anti-shrinkage special-shaped drill bit system to perform rotary drilling in the long casing until a hole is formed; at the same time, use a steel cage suspension pre-assembly system to pre-assemble the steel cage 18 in sections at the extension hole 16;

[0066] Step 4: Use the crane 15 to hoist and transversely move the steel cage 18 in the extension hole 16 as a whole at one time; use the steel cage positioning guide frame 17 to guide the steel cage 18, so that the crane 15 lowers the steel cage 18 to the designated position;

[0067] Step 5: Pour concrete, and after the concrete has initially set, remove the long casing.

[0068] It should be noted that the parts in this embodiment that are the same or similar to those in the second embodiment can be referenced to each other and will not be described in detail in this application.

[0069] Embodiment 4

[0070] As another embodiment, this embodiment 4 proposes, on the basis of the embodiment 3, a more specific method for rotary drilling pile foundation with a long casing in a water-rich and permeable stratum, comprising the following steps:

[0071] Step 1: construct the extension hole 16 near the designed pile foundation area;

[0072] Step 2: Press the first section of the lower casing 1-2 into the ground at the designed pile foundation point, hoist the upper casing 1-1 into place, install the long casing hoop auxiliary welding system, weld the lower casing 1-2 and the upper casing 1-1; weld the casings in sections in sequence until the long casing is completed;

[0073] Step 3: Use an anti-shrinkage special-shaped drill bit system to perform rotary drilling in the long casing until a hole is formed; at the same time, use a steel cage suspension pre-assembly system at the extension hole 16 to pre-assemble the steel cage 18 in sections.

[0074] like Figures 4 to 6 As shown, in the long casing, an anti-shrinkage special-shaped drill bit system is used for rotary drilling operations; start the rotary drilling rig, accurately connect the center axis 7 with the drilling rig power output shaft to ensure that the drill bit rotates stably during the drilling process. As the drill bit drills, the pressure relief channel 8 releases the water pressure in the water-rich and permeable stratum in time, balances the pressure difference between the inside and outside of the hole, and prevents the shrinkage phenomenon from occurring. The spiral blade 13 and the blade tooth 14 at the bottom of the cutting tooth 10 work together, the blade tooth 14 breaks the rock and soil, and the spiral blade 13 transports the cut soil to the outside of the hole. During the drilling process, closely observe the operating parameters of the drilling rig, such as torque, footage speed, etc., adjust the drilling parameters in time according to the changes in the formation, and ensure the quality and progress of the hole. At the same time, regularly check the wear of the drill bit, and replace the severely worn cutting teeth in time to ensure the drilling efficiency.

[0075] like Figure 7 and Figure 8 As shown, at the extension hole 16, the steel cage suspension pre-assembly system is used to pre-assemble the steel cage 18 in sections. First, build the steel cage positioning guide frame 17, assemble and firmly fix the steel cage limit pipe 17-1, the fixing rod 17-2, the connecting rod 17-3 and the supporting rod 17-4 according to the design requirements; then, place the steel cage positioning guide frame 17 directly above the extension hole 16, and the two are located on the same central axis; then, hoist the first section of the steel cage through the steel cage limit pipe 17-1 and lower it into the extension hole 16, and accurately adjust the position of the steel cage through the steel cage limit pipe 17-1 to ensure that its verticality is consistent with the design requirements.

[0076] The movable limiting rod 19-1 of the steel cage anti-sinking device 19 is passed through the through hole 16-1 and the steel cage 18, and the support 19-2 is stably supported on the ground. After the first section of the steel cage 18 is temporarily supported and positioned, the second section of the steel cage is hoisted and docked with the first section of the steel cage. The connection parts of the upper and lower steel cages are welded or mechanically connected using the gap between the steel cage limiting pipe 17-1 and the extension hole 16; finally, the above steps are repeated, and the sections are assembled in sequence until a complete steel cage 18 is formed.

[0077] Step 4: Use the crane 15 to hoist and transversely move the steel cage 18 in the extension hole 16 as a whole at one time; use the steel cage positioning guide frame 17 to guide the steel cage 18, so that the crane 15 lowers the steel cage 18 to the specified position.

[0078] like Fig. 9 As shown, a crane 15 of suitable tonnage is selected, such as a truck crane or crawler crane that meets the requirements of the weight and lifting radius of the steel cage, and the pre-assembled steel cage 18 in the extension hole 16 is lifted up smoothly at one time by the crane. Under the command of a professional signal commander, the steel cage 18 is slowly moved horizontally to the top of the long casing in the rotary drilled hole. During the lifting process, the verticality of the steel cage is maintained to prevent it from shaking, twisting, etc.

[0079] The steel cage is accurately lowered into the long casing. During the lowering process, the steel cage positioning guide frame 17 can also be used to guide the steel cage to ensure that it is smoothly lowered to the designed elevation position.

[0080] Step 5: Pour concrete. After the concrete has initially set, remove the long casing. Use the conduit method to pour concrete. Install the conduit accurately to the bottom of the hole, and keep the bottom of the conduit at a certain distance from the bottom of the hole. Use a concrete delivery pump to continuously and quickly deliver concrete to the conduit. As the concrete is continuously poured, gradually lift the conduit to ensure that the concrete always buries the conduit to a certain depth to prevent the conduit from being pulled out of the concrete surface and causing quality accidents such as broken piles. During the pouring process, closely observe the pouring height and pouring conditions of the concrete, and adjust the pouring speed and the lifting height of the conduit in a timely manner.

[0081] After the concrete pouring is completed and reaches the initial setting state, use a special casing removal device to slowly pull out the long casing. During the removal process, pay attention to the solidification of the concrete and the quality of the pile body to prevent the pile body from shrinking in diameter, breaking, and other defects due to the casing being removed too quickly or by improper methods. The removed casing should be cleaned and maintained in time for reuse

[0082] It should be noted that the parts in this embodiment that are the same or similar to those in Embodiment 3 can be referenced to each other and will not be described in detail in this application.

[0083] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A long casing rotary drilling pile foundation in a water-rich and permeable stratum, characterized in that: include: Long casing hoop auxiliary welding system, anti-shrinkage special-shaped drill bit system and steel cage suspension pre-assembly system; the long casing includes upper casing and lower casing; The long casing hoop auxiliary welding system includes an upper hoop unit ring and a lower hoop unit ring; the upper hoop unit ring is arranged at the bottom of the upper casing, and the lower hoop unit ring is arranged at the top of the lower casing; the gap between the upper hoop unit ring and the lower hoop unit ring is the casing welding groove; the anti-shrinkage special-shaped drill bit system is vertically arranged in the long casing, and the anti-shrinkage special-shaped drill bit system includes an arc-shaped drill barrel; a pressure relief channel is arranged on the side wall of the arc-shaped drill barrel; cutting teeth are arranged at the bottom of the arc-shaped drill barrel; the steel cage suspension pre-assembly system includes an extension hole and a steel cage anti-sinking device; the extension hole is inserted into the ground, and the side wall exposed to the ground is penetrated by a through hole; the bottom of the steel cage anti-sinking device is fixed to the ground around the extension hole, and the end is inserted into the through hole; a steel cage positioning guide frame is arranged above the extension hole, and a steel cage is penetrated inside the steel cage positioning guide frame; the crane is parked on the ground in the long casing construction area.

2. The long casing rotary drilling pile foundation in water-rich and permeable strata according to claim 1 is characterized by: The upper hoop unit ring and the lower hoop unit ring are symmetrical structures in an upper and lower manner; the side walls at both ends of the upper hoop unit ring and the lower hoop unit ring are connected with a transverse connection system, the transverse connection system includes a transverse fixing plate and an angle plate, the transverse fixing plate is connected to the two ends of the upper hoop unit ring and the lower hoop unit ring, and bolts are passed through and fixed on the sides of adjacent transverse fixing plates; a vertical connection system is provided on the middle side walls of the upper hoop unit ring and the lower hoop unit ring; the vertical connection system includes a vertical fixing plate and an ear plate; the vertical fixing plate is an L-shaped structure and is fixed to the side walls of the upper hoop unit ring and the lower hoop unit ring, and adjacent vertical fixing plates are fitted through the ear plates; a vertical bubble level and a transverse bubble level are provided on the side walls of the ear plates.

3. The long casing rotary drilling pile foundation in water-rich and permeable strata according to claim 1 is characterized by: The pressure relief channel is circumferentially distributed on the side wall of the arc-shaped drill barrel and presents an arc-shaped groove structure. A pressure relief strip is provided on the inner wall of the pressure relief channel. A gauge cutter is provided on the side wall of the arc-shaped drill barrel. The cutting teeth include spiral blades and cutting teeth. A rotating shaft is provided at the center of the cutting teeth, one end of the spiral blade is fixed on the rotating shaft, and the spiral blades are circumferentially distributed around the rotating shaft. A central shaft is fixed through the center of the arc-shaped drill barrel, and the top of the central shaft is higher than the arc-shaped drill barrel.

4. The long casing rotary drilling pile foundation in water-rich and permeable strata according to claim 1 is characterized by: The extension hole is a full casing structure, the depth of which is consistent with the length of the steel cage, and the inner diameter is larger than the outer diameter of the steel cage; the extension hole is higher than the ground surface, and a through hole is provided on the top; the steel cage anti-sinking device includes a movable limit rod and a support; the bottom of the support is fixed to the ground around the extension hole; the support is penetrated by a movable limit rod, and the end of the movable limit rod is inserted into the through hole; the inner diameter of the through hole is larger than the outer diameter of the movable limit rod.

5. The long casing rotary drilling pile foundation in water-rich and permeable strata according to claim 1 is characterized by: The steel cage positioning guide frame includes a steel cage limiting pipe; support rods are provided at the four corners of the steel cage positioning guide frame, and the bottom of the support rods is fixed to the ground; connecting rods are connected between the support rods; the steel cage limiting pipe is located directly above the extension hole; the side wall of the steel cage limiting pipe is connected to a fixing rod, and the steel cage limiting pipe is arranged on the upper part of the supporting rod through the fixing rod. The center positions of the steel cage limiting pipe and the extension hole are located in the same straight line.

6. The method for rotary drilling pile foundation in water-rich and permeable strata with long casing according to claims 1 to 5, characterized in that: The following steps are involved: Step 1: construct the extension hole near the designed pile foundation area; Step 2: Press the first section of the lower casing into the ground at the designed pile foundation point, hoist the upper casing into place, install the long casing hoop auxiliary welding system, weld the lower casing and the upper casing; weld the casing in sections in sequence until the long casing is completed; Step 3: Use the anti-shrinkage special-shaped drill bit system to perform rotary drilling in the long casing until a hole is formed; at the same time, use the steel cage suspension pre-assembly system to pre-assemble the steel cage into sections at the extension hole; Step 4: Use a crane to hoist and transversely move the steel cage in the extension hole as a whole at one time; use a steel cage positioning guide frame to guide the steel cage, so that the crane lowers the steel cage to the designated position; Step 5: Pour concrete, and after the concrete has initially set, remove the long casing.

7. The method for pile foundation construction with long casing rotary drilling in water-rich and permeable strata according to claim 6 is characterized by: Vertical fixing plates are fixed to the side walls of the upper hoop unit ring and the lower hoop unit ring, and adjacent vertical fixing plates are fitted together by ear plates; vertical bubble levels and horizontal bubble levels are provided on the side walls of the ear plates; in the step two, when installing the long casing hoop auxiliary welding system, the upper hoop unit ring and the lower hoop unit ring are adjusted and positioned by the vertical bubble level and the horizontal bubble level to ensure the installation accuracy of the long casing.

8. The method for pile foundation construction with long casing rotary drilling in water-rich and permeable strata according to claim 6 is characterized by: In the step 2, the upper casing and the lower casing are welded through the reserved space of the casing welding groove to form a casing weld; when welding the casing in sections, it is only necessary to loosen the bolts of the long casing clamp auxiliary welding system in situ, and after the welded casing continues to be pressed into the formation and the casing to be installed is hoisted into place, tighten the bolts to complete the welding of the next section.

9. The method for pile foundation construction with long casing rotary drilling in water-rich and permeable strata according to claim 6, characterized in that: In the step three, the steel cage anti-sinking device includes a movable limiting rod and a support; the bottom of the support is fixed to the ground around the extension hole; the support is penetrated by a movable limiting rod, and the end of the movable limiting rod is inserted into the through hole; when the steel cage is pre-assembled in sections, the steel cage is temporarily supported and positioned by passing the movable limiting rod through the through hole and the steel cage, and then the upper and lower sections of the steel cage are connected.

10. The method for pile foundation construction with long casing rotary drilling in water-rich and permeable strata according to claim 6, characterized in that: In the step three, the anti-shrinkage special-shaped drill bit system includes an arc-shaped drill barrel; a pressure relief channel is provided on the side wall of the arc-shaped drill barrel; a cutting tooth is provided at the bottom of the arc-shaped drill barrel; the cutting tooth includes a spiral blade and a cutting tooth; a rotating shaft is provided at the center of the cutting tooth, one end of the spiral blade is fixed on the rotating shaft, and the spiral blades are distributed around the circumference of the rotating shaft; a central shaft is fixed through the center of the arc-shaped drill barrel, and the top of the central shaft is higher than the arc-shaped drill barrel; when rotary drilling is carried out in a long casing using the anti-shrinkage special-shaped drill bit system, the rotary drilling rig is started, and the central shaft is accurately connected to the power output shaft of the drilling rig; as the drill bit drills, the pressure relief channel releases the water pressure in the formation in time; the spiral blade and the cutting tooth at the bottom of the cutting tooth work together, the cutting tooth crushes the rock and soil, and the spiral blade transports the cut soil to the outside of the hole.

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