A rotary cutting and extrusion device for static pressure bottom expansion piles in loess areas and a construction method thereof

Abstract

The invention discloses a rotary cutting and extruding device for static pressure bottom expansion piles in loess areas and a construction method thereof, comprising a mold pile, the mold pile is composed of a plurality of straight pile unit tubes and a rotary cutting and bottom expansion mold, a motor and an annular guide rail are arranged in the straight pile tube at the bottom of the straight pile unit tube, and the rotary cutting and bottom expansion mold comprises four curved surface rotary cutting blades, the four curved surface rotary cutting blades form an inverted conical pile tip, the top of the inverted conical pile tip is hinged to the annular guide rail through a hinge; a hydraulic rod is fixed on the curved surface rotary cutting blade, the output end of the hydraulic rod extends to the inner wall of the curved surface rotary cutting blade, the non-jacking end of the hydraulic rod is fixed on a support, and the rotating shaft of the motor is fixed at the center of the support. The static pressure bottom expansion pile rotary cutting and extruding device is used to carry out straight pile pressing and expansion end hole forming construction, so as to realize mechanized and standardized bottom expansion pile hole forming, reduce the construction risk of the expansion end, and with the pressing in of the pile mold and rotary cutting and extruding, the loess around the pile is effectively compacted, the collapsibility of the loess around the pile is reduced, and the bearing capacity of the single pile is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of base expansion pile equipment, and in particular relates to a static pressure base expansion pile rotary cutting and extrusion device in a loess region and a construction method thereof. Background Art

[0002] Due to its strong anti-overturning ability, the expanded bottom pile is widely used in western power transmission lines, bridge pile foundations and other projects. At present, the construction methods of expanded bottom piles mainly include bored cast-in-place expanded bottom piles and high-pressure rotary spray expanded bottom piles. The former has a more complicated construction process and causes greater disturbance to the soil around the borehole; although the latter can ensure that the bottom is expanded while rotary spraying, the error caused during the construction process is large, and the construction noise and mud have a greater environmental pollution. In addition, the mud water infiltrating into the collapsible loess layer will also increase the negative friction resistance on the pile side, thereby affecting the bearing capacity of the pile foundation. The use of static pressure method to construct expanded bottom piles can effectively solve the above problems, but when prefabricated expanded bottom piles are used for construction, it is difficult to directly use the static pressure method due to the existence of the expanded end. Therefore, it is particularly important to design a static pressure expanded bottom pile rotary cutting and extrusion device in loess areas. Summary of the invention

[0003] The object of the present invention is to provide a rotary cutting and extruding device for static pressure expanded piles in loess areas, so that the loess around the piles can be effectively compacted, thereby reducing the loess's collapsibility.

[0004] Another object of the present invention is to provide a construction method for a static pressure bottom expansion pile rotary cutting and extrusion device in loess areas.

[0005] The technical solution adopted by the present invention is a static pressure expanded bottom pile rotary cutting and extrusion device in the loess region, including a mold pile, the mold pile is composed of a plurality of threaded straight pile unit tubes and an expanded end rotary cutting structure, a motor is arranged inside the straight pile tube located at the bottom of the straight pile unit tube, an annular guide rail is arranged at the bottom end of the straight pile tube, and the expanded end rotary cutting structure includes four curved surface rotary cutting blades, the four curved surface rotary cutting blades are surrounded together to form an inverted cone pile tip, and the top of the inverted cone pile tip is hinged to the annular guide rail by an arc hinge; a hydraulic rod is fixed on each curved surface rotary cutting blade, the output end of the hydraulic rod extends to the inner wall of the curved surface rotary cutting blade, the non-pushing ends of the four hydraulic rods are fixed on the support, and the bottom end of the motor shaft of the motor is fixed at the center position of the support.

[0006] The present invention is also characterized in that:

[0007] The motor is fixed to the inner wall of the straight pile tube through a bracket.

[0008] Another technical solution adopted by the present invention is a construction method of a static pressure bottom expansion pile rotary cutting and extrusion device in loess areas, which is specifically:

[0009] Step 1, bury the casing at the determined pile position, and then press the part of the mold pile body after the rotation into the foundation soil with a holding press. When the pile height above the ground that is not pressed into the soil is suitable for the rotation of the straight pile unit tube, stop pressing and perform the rotation operation. The rotation and pressing are performed alternately, and the above construction process is repeated until the length of the pressed pile reaches the design requirement, then stop the rotation and pressing of the straight pile tube, and the hole forming operation of the straight pile section is completed;

[0010] Step 2: The four output ends of the hydraulic rod output jacking at the same time, pushing the four curved surface rotary cutting blades to squeeze and expand in four directions until the designed bottom expansion angle requirements are reached. After preliminary support, the hydraulic rod is controlled to slowly shrink. The shrinkage of the hydraulic rod drives the four curved surface rotary cutting blades to converge inward to form a conical pile tip. The first soil squeezing is completed;

[0011] Step 3, after the polymerization is completed, the four curved surface rotary cutting blades are rotated horizontally at a certain angle, and the motor 3 drives the four curved surface rotary cutting blades to rotate along the annular guide rail; after rotating a certain angle, the soil is squeezed again. In the final stage, after the last soil squeezing, when the four curved surface rotary cutting blades reach the designed squeezing and expansion angle, the telescopic length of the hydraulic rod is kept unchanged, that is, the bottom expansion angle is kept unchanged, and the motor is started. Through the transmission of the rotating shaft and the hydraulic rod, the four curved surface rotary cutting blades are driven to rotate horizontally along the annular guide rail, and the soil that has not been squeezed is peeled, so that the expansion head forms a truncated cone-like space. At this point, the bottom expansion operation is completed;

[0012] Step 4, after the bottom expansion is completed, lower the rotary sprinkler head and the slurry delivery conduit to the bottom of the mold pile, then shrink the length of the hydraulic rod to drive the curved rotary cutting blades to converge inward, then slowly pull out and disassemble the straight pile tube above the ground, and after all the mold piles are pulled out, carry out the hole cleaning operation. After the hole cleaning is completed, the pouring operation is carried out, and the method of vibrating and pouring is adopted. After the pouring is completed, the casing at the hole mouth is withdrawn, and the construction of the static pressure mold pouring bottom expansion pile is completed.

[0013] The beneficial effect of the present invention is that the bottom-enlarged pile constructed by static pressure method using the bottom-enlarged mold achieves the purpose of pile pressing and hole forming. As the pile mold is pressed in, the loess around the pile is effectively compacted, reducing the collapsibility, thereby improving the bearing capacity of the single pile. The use of the enlarged end rotary cutting tool for enlarged end hole forming can reduce the risk of manual construction of the enlarged end, realize mechanized and standardized enlarged end generation, and the mold can be withdrawn after hole forming for secondary use, reducing engineering costs. Due to the rotary cutting and extrusion effect, the soil around the pile falls less, reducing the workload of hole cleaning, and the construction process is also relatively simple, thereby improving construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a mold pile of a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions of the present invention;

[0015] Figure 1-1 It is a structural schematic diagram of a straight pile barrel in a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions according to the present invention;

[0016] Figure 1-2 It is a structural schematic diagram of a bottom straight pile barrel in a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions according to the present invention;

[0017] Figure 2 It is a schematic diagram of a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions according to the present invention;

[0018] Figure 3 It is a structural schematic diagram of a hydraulic rod in a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions according to the present invention;

[0019] Figure 4 It is a schematic diagram of a curved surface rotary cutting blade in a rotary cutting and extrusion device for static pressure bottom expansion piles in loess regions according to the present invention;

[0020] Figure 5 It is a schematic diagram of the rotation of the rotary cutting blade in a rotary cutting and extrusion device for static pressure pile expansion in loess areas of the present invention;

[0021] Figure 6 It is a schematic diagram of a rotary cutting and extrusion device for static pressure pile expansion in loess areas for extrusion and expansion operations according to the present invention;

[0022] Figure 7 This is a diagram showing the effect of the extrusion and expansion of a rotary cutting and extrusion and expansion device for static pressure bottom expansion piles in loess areas according to the present invention;

[0023] Figure 8 The present invention is a schematic diagram of rotary cutting of a device for rotary cutting and extrusion of static pressure expanded piles in loess regions.

[0024] In the figure, 1. straight pile unit cylinder, 2. straight pile cylinder, 3. motor, 4. rotating shaft, 5. hydraulic rod, 6. curved surface rotary cutting blade, 7. annular guide rail. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The present invention provides a rotary cutting and extruding device for static pressure bottom expansion piles in loess areas, such as Figure 1 As shown in the figure, it is a schematic diagram of the overall outline of the mold pile. The mold pile is composed of multiple Figure 1-1 The straight pile unit tube 1 which can be screwed together as shown and Figure 1-2 The rotary cutting and bottom expanding device shown is composed of screw connections. The straight pile unit tube 1 meets different pile length design requirements by screwing different numbers of straight pile tubes 2. A motor 3 is arranged inside the straight pile tube 2 at the bottom of the straight pile unit tube 1, and the motor 3 is fixed to the inner wall of the straight pile tube 2 through a bracket.

[0027] like Figure 2 to Figure 4 As shown, the bottom end of the straight pile tube 2 is provided with an annular guide rail 7, and the expanded end rotary cutting structure includes four curved surface rotary cutting blades 6, which are surrounded together to form an inverted conical pile tip, and the top of the inverted conical pile tip is hinged to the annular guide rail 7 through an arc hinge; a hydraulic rod 5 is fixed on each curved surface rotary cutting blade 6, and the output end of the hydraulic rod 5 extends to the inner wall of the curved surface rotary cutting blade 6, and the non-pushing ends of the four hydraulic rods 5 are fixed on the support, and the bottom end of the rotating shaft 4 of the motor 3 is fixed at the center position of the support; the extrusion and expansion principle is as follows Figure 2 As shown, the four output ends of the hydraulic rod 5 output jacking simultaneously, pushing the four curved surface rotary cutting blades 6 to cut the soil while squeezing outwards, completing the rotary cutting generation and soil squeezing action of the expanded end.

[0028] The rotation principle is as follows Figure 5 As shown, the motor 3 provides a rotational force to drive the rotating shaft 4 to rotate. The bottom end of the rotating shaft 4 is welded and fixed to the support. During cutting, the motor 3 drives the four curved rotary cutting blades 6 to rotate along the annular guide rail 7 to achieve rotary cutting and extrusion operations on soil in different angle areas.

[0029] The specific operation steps are: bury the casing at the determined pile position, and then use a clamping press to press the part of the mold pile body after screwing into the foundation soil. When the pile height above the ground that has not been pressed into the soil is suitable for workers to screw the straight pile barrel, stop pressing, and the workers will perform the screwing operation. The screwing and pressing are carried out alternately, and the above construction process is repeated until the length of the pressed pile reaches the design requirement. Then the screwing and pressing of the straight pile barrel are stopped, and the drilling operation of the straight pile section is completed.

[0030] like Figure 6 As shown in the figure, after the drilling operation of the straight pile section is completed, the pile length reaches the design requirement, and then the bottom expansion operation is carried out. Figure 2 As shown, the four output ends of the hydraulic rod 5 simultaneously output jacking, pushing the four curved surface rotary cutting blades 6 to expand in four directions until the designed bottom expansion angle is reached, such as Figure 7 After the initial support, the hydraulic rod 5 is controlled to slowly contract, and the contraction of the hydraulic rod 5 drives the four curved surface rotary cutting blades 6 to converge inward to form a conical pile tip, and the first soil extrusion is completed.

[0031] After the polymerization is completed, the four curved surface rotary cutting blades 6 are rotated horizontally at a certain angle. The rotation principle is as follows: Figure 5 As shown, the motor 3 provides the rotational force to drive the rotating shaft 4 to rotate, and the bottom end of the rotating shaft 4 is welded and fixed to the support, so the motor 3 drives the four curved rotary cutting blades 6 to rotate along the annular guide rail 7; after rotating for a certain angle, the soil is squeezed again, and the squeezing and expansion principle is the same as the first squeezing and expansion process; according to the quality of the hole expansion, the angle can be rotated in sequence, and the soil squeezing process can be carried out multiple times, so that the squeezing and expansion process of the head space can be made symmetrical and orderly as much as possible, and the squeezed and expanded space can be symmetrical and evenly distributed.

[0032] After the last soil compaction, Figure 8 As shown, when the four curved surface rotary cutting blades 6 reach the designed extrusion and expansion angle, the telescopic length of the hydraulic rod 5 is kept unchanged, that is, the bottom expansion angle is kept unchanged, and the motor 3 is started. Through the transmission of the rotating shaft 4 and the hydraulic rod 5, the four curved surface rotary cutting blades 6 are driven to rotate horizontally along the annular guide rail 7 to rotary cut the soil that has not been squeezed, so that the expansion head forms a relatively complete frustum-like space. At this point, the bottom expansion operation is completed.

[0033] After the bottom expansion is completed, the rotary sprinkler head and the slurry delivery conduit are lowered to the bottom of the mold pile, and then the length of the cross-shaped hydraulic rod is contracted to drive the rotary cutting blades to converge inward; during the pile pulling process, the straight pile unit tube above the ground is slowly pulled up and removed; if the height of the pile body pulled out of the ground is too long, the weight of the pile body above the ground will increase the load on the pile pulling machine during the pile pulling operation. The load of the pile pulling machine can be reduced by spirally removing the straight pile unit tube above the ground.

[0034] When the pile body is too long, the pile body and the soil around the pile will produce a large negative friction when the pile is pulled out. The harm caused is that the load of the pile puller is increased, and the soil around the pile may be deformed or moved upward, or even cause the hole to collapse. The main measures to this end are: 1. Use smooth materials as much as possible on the outer surface of the pile body, or grind and polish the outer surface of the pile body. 2. Apply vaseline or other lubricating materials to the outer surface of the pile body before the pressing operation. By reducing the roughness of the outer surface of the pile body, the negative friction generated when the pile is pulled out can be reduced, effectively avoiding the above-mentioned harm.

[0035] While slowly lifting the mold pile, the jet spray head at the bottom of the pile performs jet spraying to spray concrete to protect the hole wall and provide preliminary support for the hole wall. The lifting speed of the mold pile should be consistent with that of the jet spray head. After all the mold piles are pulled out, the jet spraying operation is stopped, the jet spray head is withdrawn, and the sedimentation thickness of the slag at the bottom of the hole is checked. If it exceeds the specified thickness, a hole cleaning operation is performed. After the hole cleaning is completed, the steel cage and grouting conduit are lowered for pouring. The method of vibrating and pouring is adopted. After the pouring is completed, the casing at the hole mouth is withdrawn. At this point, the construction of the static pressure mold pouring and bottom expansion pile is completed.

[0036] Compared with the traditional construction methods of bored cast-in-place expanded bottom piles and high-pressure rotary grouting expanded bottom piles, the present invention has the following advantages:

[0037] The method of combining rotary cutting and extrusion expansion for the expansion end construction can reduce the risk of manual construction of the expansion end, realize mechanized and standardized expansion end generation, and effectively reduce the amount of hole cleaning operations. It is a low-vibration, low-noise, and pollution-free pile bottom expansion method. The pile mold is pressed into the hole by static pressure method and the expansion end is rotary cut, so that the loess around the pile is effectively compacted, the loess collapse is reduced, and the bearing capacity of the single pile is improved. The straight pile of the mold pile is composed of several sections of unit straight pile tubes spliced ​​together by spiral. The unit straight pile tube is convenient for transportation, storage, handling and disassembly. Through spiral connection, the design requirements of different pile lengths can be met. By controlling the different telescopic lengths of the hydraulic rod, the construction requirements of different bottom expansion angles can be met, and it has the characteristics of flexible construction. The pile mold of the present invention is pressed into the soil by a rigid pile delivery device. When the mold pile reaches the specified elevation, the bottom expansion operation is carried out at the bottom of the mold pile by a rotary cutting and extrusion device. After the hole is completely formed, the pile body mold is pulled out by a holding press, realizing the dual-purpose of one machine, saving the cost of pile pressing, and simplifying the construction process. After the hole is formed, the mold can be withdrawn for secondary use, reducing engineering costs.

Claims

1. A rotary cutting and extrusion device for static pressure bottom expansion piles in loess areas, characterized in that: The mold pile comprises a mold pile, wherein the mold pile is composed of a plurality of straight pile unit tubes (1) connected by threads and an enlarged end rotary cutting structure, wherein a motor (3) is arranged inside the straight pile tube (2) located at the bottom of the straight pile unit tube (1), and an annular guide rail (7) is arranged at the bottom end of the straight pile tube (2), and the enlarged end rotary cutting structure comprises four curved surface rotary cutting blades (6), wherein the four curved surface rotary cutting blades (6) are surrounded together to form an inverted conical pile tip, and the top of the inverted conical pile tip is hinged to the annular guide rail (7) through an arc hinge; a hydraulic rod (5) is fixed on each of the curved surface rotary cutting blades (6), and the output end of the hydraulic rod (5) extends toward the inner wall of the curved surface rotary cutting blade (6), and the non-pushing ends of the four hydraulic rods (5) are fixed on a support, and the bottom end of the rotating shaft (4) of the motor (3) is fixed at the center position of the support; The construction method of the static pressure bottom expansion pile rotary cutting and extrusion device in the loess region is specifically as follows: Step 1, bury the casing at the determined pile position, and then press the part of the mold pile body after the rotation into the foundation soil with a holding press. When the pile height above the ground that is not pressed into the soil is suitable for the rotation of the straight pile unit tube, stop pressing and perform the rotation operation. The rotation and pressing are performed alternately, and the above construction process is repeated until the length of the pressed pile reaches the design requirement, then stop the rotation and pressing of the straight pile tube, and the hole forming operation of the straight pile section is completed; Step 2: The four output ends of the hydraulic rod output jacking at the same time, pushing the four curved surface rotary cutting blades to squeeze and expand in four directions until the designed bottom expansion angle requirements are reached. After preliminary support, the hydraulic rod is controlled to slowly shrink. The shrinkage of the hydraulic rod drives the four curved surface rotary cutting blades to converge inward to form a conical pile tip. The first soil squeezing is completed; Step 3, after the polymerization is completed, the four curved surface rotary cutting blades are rotated horizontally at a certain angle, and the motor drives the four curved surface rotary cutting blades to rotate along the annular guide rail; after the rotation, the soil is squeezed again. In the final stage, after the last soil squeezing, when the four curved surface rotary cutting blades reach the designed squeezing and expansion angle, the extension length of the hydraulic rod is kept unchanged, that is, the bottom expansion angle is kept unchanged, and the motor is started. Through the transmission of the rotating shaft and the hydraulic rod, the four curved surface rotary cutting blades are driven to rotate horizontally along the annular guide rail, and the soil that has not been squeezed is peeled, so that the expansion head forms a truncated cone-like space. At this point, the bottom expansion operation is completed; Step 4, after the bottom expansion is completed, lower the rotary sprinkler head and the slurry delivery conduit to the bottom of the mold pile, then shrink the length of the hydraulic rod to drive the curved rotary cutting blades to converge inward, then slowly pull out and disassemble the straight pile tube above the ground, and after all the mold piles are pulled out, carry out the hole cleaning operation. After the hole cleaning is completed, the pouring operation is carried out, and the method of vibrating and pouring is adopted. After the pouring is completed, the casing at the hole mouth is withdrawn, and the construction of the static pressure mold pouring bottom expansion pile is completed.

2. The device for rotary cutting and extruding of static pressure piles in loess areas according to claim 1 is characterized in that: The motor (3) is fixed to the inner wall of the straight pile tube (2) via a bracket.

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