A construction device and a pile-forming construction method suitable for a composite pile

Abstract

The present application relates to a kind of construction device and pile-forming construction method suitable for composite pile.The construction device and pile-forming construction method of being equipped with inner tube moving device form new type composite pile, including inner pile and outer pile, inner pile is wholly or partially wrapped by outer pile in length range;The inner pile is prestressed concrete pile or steel pile;The outer pile is by super-fluidity concrete with 160-240mm slump, including enlarged body section and column section;The enlarged body section of the outer pile is provided with one or two or more, is provided in the bottom and / or middle and / or top of outer pile;The maximum outer diameter or cross section maximum diagonal dimension of the inner pile is d, the outer diameter of enlarged body section is D, then there is: D≥1.5d.The composite pile formed by the method of the present application is better in energy saving, emission reduction and low carbon effect, and has higher pile quality, larger pile end resistance and stronger pile bearing capacity.

Description

Technical Field

[0001] This invention belongs to the field of building pile construction, specifically relating to a construction method for composite piles. Background Technology

[0002] In building pile foundations, cement-soil composite piles account for a certain proportion of soil layers with a bearing capacity characteristic value not exceeding 260 kPa. In terms of load-bearing capacity, cement-soil composite piles transform the traditional small-diameter, long-shaft end-bearing friction piles of static pressure precast pipe piles into large-diameter, short-shaft end-bearing friction piles, achieving energy-saving and carbon-reduction effects. The bearing capacity of cement-soil composite piles is mainly composed of the friction between the outer pile (cement-soil pile) and the surrounding soil. At the same time, the bond strength between the outer pile (cement-soil pile) and the inner pile (precast pipe pile) is affected by many factors such as soil quality, cement grout injection volume, mixing technology, mixing time, and groundwater. Sometimes, the bond between the inner pile (precast pipe pile) and the outer pile (cement-soil pile) is not firm. When the top of the inner pile (precast pipe pile) is under pressure, relative displacement occurs between the inner pile (precast pipe pile) and the outer pile (cement-soil pile), resulting in poor pile quality stability of cement-soil composite piles. According to the "Technical Specification for Building Pile Foundations" JGJ94-2008, the standard value of the ultimate end resistance of the same soil layer is... q pk It is the standard value of the limiting side resistance. q sik 20 to 40 times, or even higher. Summary of the Invention

[0003] To address the shortcomings of existing cement-soil composite piles and their construction methods, this invention proposes a composite pile and its construction method. The resulting composite pile exhibits better energy saving, emission reduction, and low carbon emissions, higher pile quality, greater end resistance, and stronger bearing capacity.

[0004] The technical solution adopted in this invention is as follows: a construction device suitable for composite piles, including a power head device, a concrete conversion reducer, a transition reducer, and a drilling tool. The upper end of the drilling tool is connected to the main shaft output end of the power head device in sequence through the transition reducer and the concrete conversion reducer. An inner tube is provided, which is coaxially fitted inside the drilling tool. The upper end of the inner tube passes through the transition reducer, the concrete conversion reducer, and the upper end of the main shaft hole of the power head device in sequence and is fixed to the inner tube moving device. The lower end of the inner tube is connected to the lower end of the drilling tool through an enlarging device. The inner tube moving device controls the axial up and down movement of the inner tube relative to the drilling tool to realize the opening and retraction of the enlarging device. The drilling tool drives the inner tube to rotate together. A double-opening drill tip device is provided at the bottom end of the drilling tool. After the inner tube and the drilling tool are coaxially fitted, the annular cavity formed between the outer edge of the inner tube and the inner wall of the core tube of the drilling tool is connected to the inner cavity of the concrete conversion reducer through the inner cavity of the transition reducer, forming a grouting channel for superfluid concrete.

[0005] Furthermore, the aforementioned construction device, specifically the concrete conversion adapter, comprises a curved input pipe, an outer sleeve, an inner sleeve, a pressure plate, a fixing plate, rolling elements, and seals. The inner sleeve has a spline B in its inner bore, with two transverse holes A at its upper end. The concrete conversion adapter is connected to the lower end of the main shaft of the power head device via the spline B and a pin penetrating the transverse holes A. The lower end of the inner sleeve has several channels that communicate with the inner cavity in the middle of the inner sleeve. The outer sleeve and the inner sleeve form a rotatable seal through two sets of rolling elements and seals, and are secured by the pressure plate and bolts. One end of the curved input pipe is fixed to the outer sleeve and then connected to the inner cavity in the middle of the inner sleeve. One end of the fixing plate is fixed to the outer cylindrical surface of the outer sleeve, and the other end is connected to the power head device to restrict the rotation of the outer sleeve.

[0006] Furthermore, in the aforementioned construction device, the inner tube moving device comprises two sets of guide brackets, cylinder lugs, pins, cylinders, a conical guide tube, an upper body, a lower body, and a sphere. Circular tracks for the sphere's movement are respectively provided on the upper and lower surfaces of the circular plate at the upper end of the inner tube. The circular tracks, along with the upper body, lower body, sphere, and bolts, form a rotary joint. The symmetrical protruding portions of the upper and lower bodies, fastened together, form a vertically movable positioning fit with the inner grooves of the two sets of guide brackets. Two cylinders are respectively fixed on the two sets of guide brackets. The piston rod ends of the cylinders are hinged to the cylinder lugs fixed on the upper body via pins. The bottom ends of the two sets of guide brackets are fixed on the power head device. The small-diameter end of the conical guide tube is fixed on the upper body and is co-centered with the inner tube.

[0007] Furthermore, in the aforementioned construction device, the enlarging diameter device comprises two or three sets of enlarging diameter structures arranged symmetrically or evenly. Each enlarging diameter structure includes a hinge shaft I, a connecting rod seat I, a connecting rod I, a hinge shaft II, a connecting rod II, a connecting rod seat II, and a hinge shaft III. The connecting rod seat I is fixed to the outer wall of the lower end of the drill core tube. The lower end of the connecting rod I is hinged to the connecting rod seat I via the hinge shaft I. The upper end of the connecting rod I is hinged to the lower end of the connecting rod II via the hinge shaft II. The upper end of the connecting rod II is hinged to the connecting rod seat II, which is fixed to the outer wall of the lower end of the inner tube, via the hinge shaft III. The core tube and spiral blades at positions corresponding to the connecting rods I and II are provided with notches for the enlarging diameter device to open and retract.

[0008] Furthermore, the aforementioned construction device, specifically the double-opening drill tip device, comprises a drill tip plate I, a plug plate I, a shaft, an ear plate seat, a plug plate II, and a drill tip plate II. Two sets of ear plate seats are symmetrically arranged on the outer wall of the lower end of the core tube of the drill bit. The upper part of one side of the drill tip plate I and the drill tip plate II respectively engages with the inner stops of the two sets of ear plate seats and is hinged through the shaft. Both the plug plate I and the plug plate II are two-step semi-circular plates, respectively fixed to the drill tip plate I and the drill tip plate II. Both the drill tip plate I and the drill tip plate II are half of an integral drill tip plate. A groove C is provided at the end face of the drill tip plate I, and a protrusion D is provided at the corresponding end face of the drill tip plate II. The drill tip plate I, along with the plug plate I and the drill tip plate II, rotates around the shaft to close or open the lower end of the core tube. The groove C and the protrusion D are fitted together, and the plug plate I and the plug plate II form a complete circle. Furthermore, the small-diameter protrusions of the plug plate I and the plug plate II are circumferentially positioned with the inner hole at the lower end of the core tube.

[0009] A method for constructing composite piles, utilizing the aforementioned construction device, includes the following steps:

[0010] 1) Assemble the pile driver for construction, and install the power head device, concrete conversion reducer, transition reducer, drilling tool, inner tube, inner tube moving device, enlarging device, and double-opening drill tip device; the inner tube moving device is connected to the pile driver hydraulic control device through a high-pressure oil pipe, the concrete delivery pump is connected to the concrete conversion reducer through a concrete delivery pipe, the enlarging device is in the retracted state, the double-opening drill tip device is in the closed state, the drill tip is aligned with the pile hole position, and the drilling tool is straightened;

[0011] 2) Start the pile driver and power head device. The power head device drives the drill bit to rotate in the downward drilling direction. Under the action of the rotating drill bit, some of the soil at the pile hole position is squeezed into the pile hole wall, and the remaining soil is transported to the ground surface outside the hole through the spiral blades on the rotating drill bit. Part of the squeezed soil is drilled to the design depth of the composite pile outer pile.

[0012] 3) Drilling, grouting concrete, and inserting internal piles;

[0013] 4) Using the internal pile driving equipment, apply vertical pressure to the partially exposed internal piles and drive the internal piles downwards until the top height of the internal pile meets the design pile top elevation of the composite pile, thus completing the construction of one composite pile.

[0014] Furthermore, in the above-mentioned composite pile construction method, step 3) includes the following steps: Keep the drill bit rotating, first inject concrete into the bottom of the drill bit's inner cavity, then slowly lift the drill bit, the concrete presses open the double-opening drill tip device, and injects it into the bottom of the outer pile hole, forming a 500-1000mm concrete column section; activate the hydraulic control system, push the inner tube downwards through the inner tube moving device, drive the enlarging diameter device to open, the enlarging diameter device rotates to squeeze the soil and expand the diameter, the enlarged diameter cavity formed is filled with the injected concrete, the soil not squeezed into the hole wall during the soil squeezing and enlarging process is transported from bottom to top along the spiral blades of the rotating drill bit under the action of the injected concrete at the bottom, lift the drill, enlarge the diameter, and inject concrete until the top elevation of the first enlarged section is reached, lift the inner pile with a lifting device, and penetrate the inner cavity of the inner tube. The inner pile is placed in the concrete cavity at the bottom of the drill bit by its own weight. The lifting tool is removed, and the hydraulic control system is activated. The inner pipe is pulled upward by the inner pipe moving device, which drives the enlarged diameter device to close. At the same time, the drill is lifted and pressure grouting is started to form a column section. This process continues until the bottom elevation of the second enlarged section is reached. The enlarged diameter device is then driven to open again, and the drill is lifted, the diameter is enlarged, and pressure grouting is continued to form an enlarged section until the top elevation of the second enlarged section is reached. The core of the second column section and the second enlarged section are both inner piles. The construction of column sections and enlarged sections is repeated in sequence until the top elevation of the concrete outer pile is reached. The resulting concrete outer pile is concentrically wrapped with the inner pile, and part of the inner pile is exposed above the top of the cast-in-place concrete outer pile. The top of the exposed inner pile is higher than the design elevation of the top of the composite pile.

[0015] Furthermore, in the above-mentioned composite pile construction method, step 3) includes the following steps: While maintaining the drill bit's rotation, first, concrete is poured in, and simultaneously, the hydraulic control system is activated. The inner tube moving device drives the enlarging diameter device to open, then the drill bit is slowly lifted. Concrete forces open the double-opening drill tip device, pouring into the bottom of the outer pile hole and the enlarged diameter cavity to form the first enlarged section. Then, the inner tube moving device is activated again, driving the enlarged diameter device to retract. The drill bit is lifted, and concrete is poured in to form a columnar section. The drilling and pouring are stopped. The inner pile is lifted using a lifting device, penetrates the inner tube cavity, and is placed in the inner cavity at the bottom of the drill bit by its own weight. Inside the concrete, the lifting equipment is removed, and the enlarging device is activated again. Drilling, enlarging, and grouting continue until the top elevation of the second enlarged section is reached. The enlarging device is then activated to retract, and drilling and grouting continue until the top elevation of the column section is reached. The core of the second enlarged section and the second column section are both inner piles. The construction of the enlarged section and the column section is repeated in sequence until the top elevation of the concrete outer pile is reached. The resulting concrete outer pile encloses the inner pile in the center, and some of the inner pile is exposed above the top of the cast-in-place concrete outer pile. The top of the exposed inner pile is higher than the design elevation of the composite pile top.

[0016] A composite pile formed according to the above-mentioned pile construction method, the composite pile structure includes an inner pile and an outer pile, the inner pile being wholly or partially enclosed by the outer pile within its length range; the inner pile is a prestressed concrete pile or a steel pile; the outer pile is composed of superfluid concrete with a slump of 160-240mm, including an enlarged section and a column section; the enlarged section of the outer pile is provided with one, two or more, located at the bottom and / or middle and / or top of the outer pile; if the maximum outer diameter or the maximum diagonal dimension of the cross-section of the inner pile is d, and the outer diameter of the enlarged section is D, then: D≥1.5d.

[0017] Furthermore, in the aforementioned composite pile, the superfluid concrete is fine stone concrete or fine aggregate concrete with a concrete strength grade of C15, C20, C25, or C30.

[0018] The beneficial effects of this invention are:

[0019] 1. The composite pile obtained through the construction method of this invention has an inner pile that is a high-strength prestressed concrete pile or a precast steel structure component with even higher strength. Centralized production and manufacturing result in excellent low-carbon emission reduction, making it the main contributor to the strength of the composite pile body. The outer pile is a low-strength (typically C15, C20, C25, or C30 strength grade) super-fluid concrete with a slump of 160–240 mm. The large end area of ​​the enlarged section of the outer pile interacts with the foundation soil to form a large end resistance, maximizing the potential for high end resistance in the foundation soil and resulting in significant energy saving and emission reduction. This is the main source of the high bearing capacity generated by the interaction between the composite pile and the surrounding soil. The reliable combination of the high-strength inner pile and the low-strength concrete outer pile containing the enlarged section forms a friction-end-bearing pile with end resistance as its primary characteristic, a prominent feature of composite piles.

[0020] 2. The composite pile obtained by the construction method of the present invention has an outer pile made of super-fluid concrete with a slump of 160-240mm. It has good fluidity and can reliably wrap around the inner pile at the corresponding position and form a seamless contact with the outer surface of the inner pile. After solidification, the inner and outer piles are firmly bonded, and the overall strength of the composite pile is improved. The high slump concrete has good pouring smoothness.

[0021] 3. The composite piles obtained by the construction method of this invention have higher strength in the concrete outer pile than in the cement-soil outer pile. During the inner pile insertion process, there is no concrete overflow, resulting in high utilization of pile materials. In contrast, cement-soil composite piles have a large amount of cement and soil overflow, making them more energy-efficient and environmentally friendly.

[0022] 4. The composite piles obtained by the construction method of this invention are driven to the design elevation of the pile top by vertical pressure, which further squeezes the concrete at the bottom of the inner pile, expands the soil around the pile, forms a larger enlarged diameter concrete body, has no loose soil at the pile end, has higher end resistance, and has good consistency of pile top elevation.

[0023] 5. The composite piles obtained by the construction method of this invention have high total bearing capacity, good quality stability, and achieve shorter pile length and lower cost.

[0024] 6. The construction method provided by the present invention has a concrete pouring channel consisting of a large annular cavity formed by the inner wall of the inner pipe and the inner wall of the drill core tube. The inner cavity of the inner pipe is used for implanting the inner pile, which not only ensures that the inner pile and the outer pile of the composite pile are concentric, but also ensures the smoothness of concrete pouring.

[0025] 7. The construction method provided by the present invention has an annular radial spoke shape at the lower part of the inner sleeve of the concrete conversion and diameter reduction device, which meets the dual requirements of torque transmission and concrete pouring channel.

[0026] 8. The construction method provided by the present invention has the expansion connecting rods of the expansion device being evenly distributed or symmetrically arranged, which is beneficial to the force balance of the inner tube during expansion and ensures the concentricity of the inner tube and the core tube of the drill bit.

[0027] 9. In the construction method provided by the present invention, when the double-opening drill tip device closes the lower end of the drill core tube, the contact surfaces of drill tip plate I and drill tip plate II adopt a convex-concave interlocking fit, and the outer diameter of the upper end of the integral circle formed by plug plate I and plug plate II is circumferentially positioned with the inner diameter of the lower end of the drill core tube, which ensures that the drill tip can reliably combine with the circumferential force during drilling, and the plug plate can reliably seal the lower end of the core tube.

[0028] 10. The construction method provided by this invention solves the problem of high-strength composite bonding of superfluid concrete outer piles and inner piles over a large pile length in existing composite piles, realizing a true composite pile of concrete outer piles and high-strength inner piles. By encapsulating and bonding the concrete outer piles and inner piles over a large pile length, the overall strength of the composite pile is improved, thereby increasing its bearing capacity. Because concrete outer piles have much lower fluidity but much higher strength than cement-soil outer piles, composite piles composed of concrete outer piles and inner piles have significant advantages over composite piles composed of cement-soil outer piles and inner piles in terms of composite pile strength and bearing capacity.

[0029] 11. The construction method provided by the present invention adopts the method of "burying" most of the inner pile length with superfluid concrete outer pile, which reliably ensures the composite length of the inner pile and the outer pile, and avoids the shortcomings of first pouring concrete outer pile and then inserting inner pile, such as difficulty in insertion and shallow insertion depth due to the low compressibility of concrete, and waste of outer pile material.

[0030] 12. The construction method provided by this invention changes the existing method of using the central cavity of the drill bit as the only grouting channel for concrete pressure grouting. Because concrete has poor fluidity, its fluidity differs greatly from that of cement slurry or mortar, making it prone to pipe blockage. This invention uses a large annular cavity formed by the inner tube and the inner wall of the drill bit core tube as the concrete conveying channel. The annular cavity has a large volume, and the axial up-and-down movement between the inner tube and the drill bit core tube can be controlled within a certain range by an inner tube moving device, increasing the fluidity of the grouting concrete. The outer pile concrete uses super-fluid fine aggregate concrete or fine stone concrete with a slump of 160-240mm. High slump and small aggregate concrete have better fluidity than ordinary concrete, which is beneficial for smooth grouting and also for the grouting and shaping of the expanded section.

[0031] 13. The construction method provided by this invention can be completed by one pile driver with dual tracks and dual power heads, or by two pile drivers working together. The construction operation is simple and the efficiency is high. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the construction device structure in Example 1.

[0033] Figure 2 This is a schematic diagram of the concrete conversion and diameter reduction structure of the construction device in Example 1.

[0034] Figure 3 yes Figure 2 EE sectional view.

[0035] Figure 4 This is a schematic diagram of the transition diameter changing structure of the construction device in Example 1.

[0036] Figure 5 This is a schematic diagram of the inner pipe moving device mechanism of the construction device in Example 1.

[0037] Figure 6 This is a schematic diagram of the enlarged diameter device structure of the construction device in Example 1 (closed state).

[0038] Figure 7 This is a schematic diagram of the enlarged diameter device structure of the construction device in Example 1 (open state).

[0039] Figure 8 This is a schematic diagram of the double-opening drill tip device structure of the construction device in Example 1 (closed state).

[0040] Figure 9 yes Figure 8 Top view.

[0041] Figure 10 yes Figure 8 FF sectional view.

[0042] Figure 11This is a schematic diagram of the double-opening drill tip device structure of the construction apparatus in Example 1 (open state).

[0043] Figure 12 This is a schematic diagram of the construction method in Example 2. Detailed Implementation Example 1

[0044] like Figures 1-11 As shown, a construction device suitable for composite piles includes a power head device (10), a concrete conversion reducer (20), a transition reducer (30), a drill bit (40), an inner tube (50), an inner tube moving device (60), an enlarged diameter device (70), and a double-opening drill tip device (80).

[0045] The power head unit (10), concrete conversion reducer (20), and transition reducer (30) are assembled together in sequence. The power head unit (10) is mounted on the piling machine. The drill bit (40) includes a core tube (41) and spirally wound helical blades. The upper end of the drill bit (40) is connected to the main shaft output end of the power head unit (10) in sequence through the transition reducer (30) and the concrete conversion reducer (20). The inner tube (50) is coaxially fitted inside the drill bit (40), and the upper end of the inner tube (50) passes through the transition reducer (30), the concrete conversion reducer (20), and the upper end of the main shaft hole of the power head unit (10) in sequence with the center, and is fixed to the inner tube moving device (60). The lower end of the inner tube (50) is connected to the lower end of the drill bit (40) through the enlarging device (70). The inner tube moving device (60) controls the axial up and down movement of the inner tube (50) relative to the drill bit (40), realizing the opening and retraction of the enlarging device (70). The drill bit (40) drives the inner tube (50) to rotate together, and a double-opening drill tip device (80) is provided at the bottom end of the drill bit (40). After the inner tube (50) and the drill bit (40) are coaxially fitted, the annular cavity formed between the outer edge of the inner tube (50) and the inner wall of the core tube of the drill bit (40) is connected to the inner cavity (23-2) of the concrete conversion diameter changer (20) through the inner cavity of the transition diameter changer (30), thus forming the grouting channel of the superfluid concrete.

[0046] Preferably, in this embodiment, such as Figure 2 and Figure 3As shown, the structure of the concrete conversion reducer (20) is as follows: it includes a bent input pipe (21), an outer sleeve (22), an inner sleeve (23), a pressure plate (24), a fixing plate (25), a rolling element (26), and a sealing element (27); the inner hole of the inner sleeve (23) is provided with a spline B, and its upper end is provided with two transverse holes A. The concrete conversion reducer (20) is connected to the lower end of the main shaft of the power head device (10) through the spline B and the pin passing through the transverse holes A; the lower end of the inner sleeve (23) forms several channels (23-1) in a spoke-like radial pattern. 23-1) communicates with the inner cavity (23-2) in the middle of the inner sleeve (23); the outer sleeve (22) and the inner sleeve (23) are connected by two sets of rolling elements (26) and a seal (27) to form a rotatable seal, which is fastened by a pressure plate (24) and bolts; one end of the curved input pipe (21) is fixed to the outer sleeve (22) and then connected to the inner cavity (23-2) in the middle of the inner sleeve (23); one end of the fixing plate (25) is fixed to the outer cylindrical surface of the outer sleeve (22), and the other end is connected to the power head device (10) to fix and restrict the rotation of the outer sleeve (22). The concrete conveying pump is connected to the curved input pipe (21) of the concrete conversion reducer (20) through the concrete conveying pipe.

[0047] Preferably, in this embodiment, such as Figure 4 As shown, the transition reducer (30) is frustum-shaped. The end with the larger diameter is fixed to the concrete transition reducer (20) via a flange.

[0048] Preferably, in this embodiment, such as Figure 5 As shown, the structure of the inner tube moving device (60) is as follows: it includes two sets of guide brackets (61), cylinder ear plates (62), pins (63), cylinders (64), conical guide tubes (65), upper body (66), lower body (67) and ball (68). The upper and lower surfaces of the circular plate (51) at the upper end of the inner tube (50) are respectively provided with circular tracks for the ball (68) to run on. The circular tracks, together with the upper body (66), lower body (67), ball (68) and bolts, form a rotary pair. The symmetrical protruding parts of the upper body (66) and lower body (67) which are fastened together form a positioning fit that can move up and down with the inner groove of the two sets of guide brackets (61). The two oil cylinders (64) are respectively fixed on the two sets of guide brackets (61). The piston rod end of the oil cylinder (64) is hinged to the oil cylinder ear plate (62) fixed on the upper body (66) through the pin (63). The bottom end of the two sets of guide brackets (61) is fixed on the power head device (10). The small diameter end of the tapered guide tube (65) is fixed on the upper body (66) and is set at the same center as the inner tube (50).

[0049] Preferably, in this embodiment, such as Figure 6 and Figure 7As shown, the structure of the enlarging diameter device (70) is: composed of two sets of enlarging diameter structures arranged symmetrically; the enlarging diameter structure includes hinge shaft I (71), connecting rod seat I (72), connecting rod I (73), hinge shaft II (74), connecting rod II (75), connecting rod seat II (76), and hinge shaft III (77); connecting rod seat I (72) is fixed on the outer wall of the lower end of the core tube (41) of the drill bit (40), and the lower end of connecting rod I (73) is connected to hinge shaft I (74). 1) Hinged to connecting rod seat I (72), the upper end of connecting rod I (73) is hinged to the lower end of connecting rod II (75) via hinge shaft II (74), the upper end of connecting rod II (75) is hinged to connecting rod seat II (76) fixed on the outer wall of the lower end of inner tube (50) via hinge shaft III (77), and the core tube (41) and spiral blades at the corresponding positions of connecting rod I (73) and connecting rod II (75) are provided with notches for the expansion diameter device (70) to open and retract.

[0050] Preferably, in this embodiment, such as Figures 8-11 As shown, the double-opening drill tip device (80) includes drill tip plate I (81), plug plate I (82), shaft (83), ear plate seat (84), plug plate II (86), and drill tip plate II (87). Two sets of ear plate seats (84) are symmetrically arranged on the lower outer wall of the core tube (41) of the drill bit (40). The upper part of one side of drill tip plate I (81) and drill tip plate II (87) respectively cooperates with the inner stops of the two sets of ear plate seats (84) and is hinged through the shaft (83). Plug plate I (82) and plug plate II (86) are both two-step semi-circular plates, which are fixed to drill tip plate I (81) and drill tip plate II (87) respectively. Drill tip plate I (81) and drill tip plate II (87) are both half of the integral drill tip plate. A groove C is provided at the corresponding end face of the drill tip plate II (87). The drill tip plate I (81) with the plug plate I (82) and the drill tip plate II (87) with the plug plate II (86) rotate around the axis (83) respectively to close or open the lower port of the core tube (41). The groove C and the plug D are fitted together. The plug plate I (82) and the plug plate II (86) form a complete circle. The small diameter bosses of the plug plate I (82) and the plug plate II (86) are circumferentially positioned with the inner hole of the lower end of the core tube (41).

[0051] The working principle of the construction device is as follows:

[0052] The lower end of the inner tube (50) is connected to the lower end of the drill core tube (41) through an enlarged diameter device (70) that is evenly or symmetrically arranged. The upper end of the inner tube (50) forms a rotating pair with the upper body (66), lower body (67), sphere (68) and bolts through the upper and lower surfaces of the circular plate (51) set at the upper end, so as to keep the central axis of the three holes of the power head device (10), the inner cavity hole of the inner tube (50) and the inner cavity hole of the drill core tube (41) coincident. The annular cavity formed between the inner tube (50) and the core tube (41) becomes the concrete pouring channel. The core tube (41) drives the inner tube (50) to rotate synchronously and in the same center. The inner cavity diameter d1 of the inner tube (50) is slightly larger than the maximum outer diameter d of the inner pile (90). Usually, d1-d=20~60mm is retained to ensure that the inner pile can pass smoothly through the inner cavity of the inner tube (50) and at the same time ensure that the verticality deviation of the inner pile (90) is not greater than 1%.

[0053] The double-opening drill tip device (80) adopts a split type. When closed, the two end faces of drill tip plate I (81) and drill tip plate II (87) are in contact with each other. Through the groove C and the protrusion D, the plug plate I (82) and plug plate II (86) form a complete circle. The small diameter protrusions of plug plate I (82) and plug plate II (86) are circumferentially positioned with the inner hole at the lower end of the core tube (41), ensuring that the two drill tip plates form an integral structure during drilling, with high strength. It also ensures that the two plug plates can reliably seal the inner hole at the bottom end of the drill core tube (41).

[0054] The opening and closing of the enlarging device (70) is controlled by the oil cylinder (64) in the inner tube moving device (60). When the piston rod of the oil cylinder (64) extends, it pushes the inner tube (50) downward, thereby driving the enlarging device (70) to open. Conversely, when the piston rod of the oil cylinder (64) retracts, it pulls the inner tube (50) upward, and the enlarging device (70) retracts. Example 2

[0055] A construction method for composite piles.

[0056] (a) The composite pile structure is as follows:

[0057] A composite pile consists of an inner pile (90) and an outer pile (100) on the same axis. The inner pile (90) is wholly or partially enclosed by the outer pile (100) along its length. The inner pile (90) is a prestressed concrete pile or a steel pile; the outer pile (100) is made of superfluid concrete with a slump of 160-240 mm and includes an enlarged section (101) and a column section (102). There may be one or more enlarged sections (101), which may be located at the bottom and / or middle and / or top of the outer pile; if the maximum outer diameter or the maximum diagonal dimension of the cross section of the inner pile (90) is d, and the outer diameter of the enlarged section (101) of the outer pile (100) is D, then: D≥1.5d.

[0058] Preferably, the superfluid concrete is fine stone concrete or fine aggregate concrete with a concrete strength grade of C15, C20, C25 or C30.

[0059] The bearing mechanism of composite piles is as follows:

[0060] The composite pile is formed by bonding the inner pile (90) and the outer pile (100) through superfluid concrete. The concrete has high strength and strong bonding force, which makes the inner and outer piles solidified as one. The outer pile has one or more enlarged sections to form a large end bearing area. When the top of the composite pile is subjected to vertical pressure, the lower end face of the enlarged section of the outer pile acts on the soil surface around the pile in contact with it. The soil surface around the pile generates a large upward bearing force on the bottom end face of the enlarged section, forming a large end resistance. This fully utilizes the high standard value of the ultimate end resistance of the soil around the pile, so that the bearing capacity of the composite pile is mainly reflected in the end resistance. The side friction of the outer surface of the outer pile only provides a secondary role in the bearing capacity of the composite pile. The resulting pile is a composite pile with high strength inner pile that meets the pile body strength requirements, low strength concrete outer pile to achieve large end resistance, and strong bonding between the inner and outer piles.

[0061] During the construction of the concrete outer pile, a portion of the inner pile is left exposed above the design elevation of the composite pile top. Vertical pressure is then applied to drive the inner pile to the composite pile top elevation. During this process, the bottom of the inner pile compresses the concrete poured below it, further expanding and compacting the adjacent surrounding soil, forming an enlarged concrete body, resulting in greater end resistance, while simultaneously preventing the overflow of the outer pile concrete. For composite piles where the bottom of the inner pile penetrates the concrete outer pile and enters the hard rock layer, a portion of the inner pile length is reserved before vertical pressure is applied, causing the bottom of the inner pile to penetrate into the hard rock layer, resulting in an even greater end resistance for the composite pile.

[0062] (II) Construction method of composite piles:

[0063] The construction device of Example 1 is used, and the construction method is as follows:

[0064] 1. Assemble the pile driver for construction, and install the power head device (10), concrete conversion reducer (20), transition reducer (30), drilling tool (40), inner tube (50), and enlarging device (70). The inner tube moving device (60) is connected to the pile driver hydraulic control device through a high-pressure oil pipe. The concrete conveying pump is connected to the concrete conversion reducer through a concrete conveying pipe. The enlarging device is in the retracted state, the double-opening drill tip device (80) is in the closed state, the drill tip is aligned with the pile hole position, and the drilling tool is straightened. Figure 12 (a)

[0065] 2. Start the pile driver and power head unit. The power head unit drives the drill bit to rotate in the downward drilling direction. Under the action of the rotating drill bit, some of the soil at the pile hole location is squeezed into the formed pile hole wall, and the remaining soil is transported to the ground surface outside the hole through the spiral blades on the rotating drill bit. Part of the squeezed soil is drilled to the design depth of the composite pile outer pile, such as... Figure 12 (b)

[0066] 3. The sequence of drilling, concrete grouting, and internal pile insertion can fall into two categories:

[0067] 3.1) Keep the drill bit rotating, first press concrete into the bottom of the drill bit's inner cavity, then slowly lift the drill bit, the concrete presses open the double-opening drill tip device, presses into the bottom of the outer pile hole, forming a 500-1000mm concrete column section (102); then start the hydraulic control system, supply oil to the rodless chamber of the cylinder (64) of the inner tube moving device, the piston rod of the cylinder (64) pushes the inner tube (50) down, drives the enlarged diameter device to open, the enlarged diameter device rotates to squeeze the soil and expand the diameter, the enlarged diameter cavity formed is filled with the press-filled concrete, the soil that is not squeezed into the hole wall during the soil squeezing and expanding process is transported from bottom to top along the spiral blades of the rotating drill bit under the action of the press-filled concrete at its bottom, lift the drill bit, expand the diameter, press-fill to the top elevation of the first enlarged body section (101), lift the inner pile (90) with the lifting device, penetrate the inner cavity of the inner tube (50), place it in the concrete at the bottom of the drill bit's inner cavity by the weight of the inner pile (90), remove the lifting device, and then start the hydraulic control system. The system supplies oil to the rod chamber of the cylinder (64) of the inner tube moving device. The piston rod of the cylinder pulls the inner tube (50) upward, driving the enlarged diameter device to close. At the same time, the drilling and pressure filling are started to form the column section (102). When the bottom elevation of the second enlarged section (101) is reached, the enlarged diameter device is driven to open again. The drilling, enlargement, and pressure filling are continued to form the enlarged section (101) until the top elevation of the second enlarged section (101) is reached. The resulting second column section (102) and the first... The core of each of the two enlarged sections (101) is an inner pile (90); the construction of the column section (102) and the enlarged section (101) is repeated sequentially until the top elevation of the concrete outer pile (100) is reached. The resulting concrete outer pile (100) encloses the inner pile (90) in a coaxial manner, with some of the inner pile (90) exposed above the top surface of the cast-in-place concrete outer pile (100). The top of the exposed inner pile (90) is higher than the design elevation of the composite pile top. Figure 12 As shown in (c), (d), (e), (f), (g), and (h).

[0068] 3.2) Keep the drill bit rotating, first press-pour concrete, and at the same time drive the enlarging device to open, then slowly lift the drill bit, the concrete presses open the double drill tip, and press-pours into the bottom of the outer pile hole and the enlarged diameter cavity to form the first enlarged body section (101). Then start the inner tube moving device, drive the enlarged diameter device to retract, lift the drill and press-pour to form a column section (102), stop lifting the drill and pressing-pour, lift the inner pile (90) with the lifting device, penetrate the inner cavity of the inner tube (50), and place it in the concrete of the inner cavity at the bottom of the drill bit by the weight of the inner pile (90). Remove the lifting device, drive the enlarged diameter device to open again, and continue lifting the drill, enlarging the diameter and pressing-pour to the second enlarged body section (102). 1) Stop at the top elevation, start the retraction enlargement device, continue drilling and grouting until the top elevation of the column section (102) is stopped. The core of the second enlarged body section (101) and the second column section (102) formed are both inner piles (90). Repeat the construction of the enlarged body section (101) and column section (102) in sequence until the top elevation of the concrete outer pile (100) is stopped. The formed concrete outer pile (100) is wrapped around the inner pile (90) in the center, and some inner piles (90) are exposed on the top surface of the cast-in-place concrete outer pile (100), and the top of the exposed inner pile (90) is higher than the design elevation of the top of the composite pile.

[0069] 4. Using the internal pile driving equipment, apply vertical pressure to the partially exposed internal pile (90) to drive the internal pile (90) downwards until the top height of the internal pile (90) meets the design pile top elevation of the composite pile, thus completing the construction of one composite pile. Figure 12 As shown in (j), (k), (m), and (n).

[0070] Formation as Figure 12 The composite pile shown in (k) consists of an inner pile (90) and an outer pile (100) on the same axis. The inner pile (90) is completely enclosed by the outer pile (100) along its length. The exemplary outer pile (100) includes three enlarged sections (101) and four column sections (102). The enlarged sections (101) are located at the bottom and middle of the outer pile (100) in the composite pile.

[0071] Or form as Figure 12 The composite pile shown in the middle (m) consists of an inner pile (90) and an outer pile (100) on the same axis. The inner pile (90) is completely enclosed by the outer pile (100) along its length. The exemplary outer pile (100) includes four enlarged body segments (101) and four columnar segments (102). The enlarged body segments (101) are located at the bottom, middle and top of the outer pile (100) in the composite pile.

[0072] Or form as Figure 12The composite pile shown in (n) consists of an inner pile (90) and an outer pile (100) on the same axis. The inner pile (90) is partially enclosed by the outer pile (100) along its length. An exemplary outer pile (100) includes three enlarged sections (101) and four column sections (102). The enlarged sections (101) are located at the bottom, middle, and top of the outer pile (100) in the composite pile.

[0073] The construction method works as follows:

[0074] The method employed partial soil displacement for borehole formation and pump-pressed concrete for the outer piles. Furthermore, the inner piles of the composite piles were mostly installed first. This approach eliminated waste of the outer pile concrete and ensured the bonding strength between the outer and inner pile concrete. The inner piles were then driven vertically to the design elevation of the composite pile. This ensured consistency in the pile top elevation and allowed for further compression of the concrete at the bottom of the inner pile, expanding the surrounding soil and creating a larger diameter concrete body, thus further improving end resistance.

Claims

1. A construction device suitable for composite piles, comprising a power head device (10), a concrete conversion reducer (20), a transition reducer (30), and a drilling tool (40), wherein the upper end of the drilling tool (40) is sequentially connected to the main shaft output end of the power head device (10) via the transition reducer (30) and the concrete conversion reducer (20), characterized in that, An inner tube (50) is provided, which is coaxially fitted inside the drill bit (40). The upper end of the inner tube (50) passes through the transition diameter reducer (30), the concrete conversion diameter reducer (20), and the upper end of the spindle hole of the power head device (10) in sequence and is fixed to the inner tube moving device (60). The lower end of the inner tube (50) is connected to the lower end of the drill bit (40) through the enlarged diameter device (70). The inner tube moving device (60) controls the axial up and down movement of the inner tube (50) relative to the drill bit (40). The expansion device (70) is opened and retracted; the drill bit (40) drives the inner tube (50) to rotate together, and the bottom end of the drill bit (40) is equipped with a double-opening drill tip device (80); after the inner tube (50) and the drill bit (40) are coaxially fitted, the annular cavity formed between the outer edge of the inner tube (50) and the inner wall of the core tube of the drill bit (40) is connected to the inner cavity (23-2) of the concrete conversion diameter changer (20) through the inner cavity of the transition diameter changer (30), thus forming the grouting channel of the superfluid concrete.

2. The construction device according to claim 1, characterized in that, The concrete conversion adapter (20) includes a curved input pipe (21), an outer sleeve (22), an inner sleeve (23), a pressure plate (24), a fixing plate (25), a rolling element (26), and a seal (27). The inner hole of the inner sleeve (23) is provided with a spline B, and its upper end is provided with two transverse holes A. The concrete conversion adapter (20) is connected to the lower end of the main shaft of the power head device (10) through the spline B and the pin passing through the transverse holes A. The lower end of the inner sleeve (23) is provided with several channels (23-1). It communicates with the inner cavity (23-2) in the middle of the inner sleeve (23); the outer sleeve (22) and the inner sleeve (23) are connected by two sets of rolling elements (26) and a seal (27) to form a rotatable seal, which is fastened by a pressure plate (24) and bolts; one end of the bent input pipe (21) is fixed to the outer sleeve (22) and then connected to the inner cavity (23-2) in the middle of the inner sleeve (23); one end of the fixing plate (25) is fixed on the outer cylindrical surface of the outer sleeve (22), and the other end is connected to the power head device (10) to fix and restrict the rotation of the outer sleeve (22).

3. The construction device according to claim 1, characterized in that, The inner tube moving device (60) includes two sets of guide brackets (61), cylinder lugs (62), pins (63), cylinders (64), conical guide tubes (65), an upper body (66), a lower body (67), and a ball (68); the upper and lower surfaces of the circular plate (51) at the upper end of the inner tube (50) are respectively provided with circumferential tracks for the ball (68) to run on, and the circumferential tracks, together with the upper body (66), the lower body (67), the ball (68), and bolts, are assembled to form a rotary joint; the upper body (66) is fastened into one piece. The symmetrical protruding parts of the lower body (67) form a positioning fit that can move up and down with the inner grooves of the two sets of guide brackets (61). The two oil cylinders (64) are fixed on the two sets of guide brackets (61). The piston rod end of the oil cylinder (64) is hinged to the oil cylinder ear plate (62) fixed on the upper body (66) through the pin (63). The bottom end of the two sets of guide brackets (61) is fixed on the power head device (10). The small diameter end of the tapered guide tube (65) is fixed on the upper body (66) and is set at the same center as the inner tube (50).

4. The construction device according to claim 1, characterized in that, The enlarging diameter device (70) comprises two or three sets of enlarging diameter structures arranged symmetrically or evenly; the enlarging diameter structure includes hinge shaft I (71), connecting rod seat I (72), connecting rod I (73), hinge shaft II (74), connecting rod II (75), connecting rod seat II (76), and hinge shaft III (77); connecting rod seat I (72) is fixed on the outer wall of the lower end of the core tube (41) of the drill bit (40), and the lower end of connecting rod I (73) is connected to hinge shaft I (74). 71) Hinged to connecting rod seat I (72), the upper end of connecting rod I (73) is hinged to the lower end of connecting rod II (75) via hinge shaft II (74), the upper end of connecting rod II (75) is hinged to connecting rod seat II (76) fixed on the outer wall of the lower end of inner tube (50) via hinge shaft III (77), and the core tube (41) and spiral blades at the corresponding positions of connecting rod I (73) and connecting rod II (75) are provided with notches for the expansion diameter device (70) to open and retract.

5. The construction device according to claim 1, characterized in that, The double-opening drill tip device (80) includes a drill tip plate I (81), a plug plate I (82), a shaft (83), an ear plate seat (84), a plug plate II (86), and a drill tip plate II (87). Two sets of ear plate seats (84) are symmetrically arranged on the outer wall of the lower end of the core tube (41) of the drill bit (40). The upper part of one side of the drill tip plate I (81) and the drill tip plate II (87) respectively cooperates with the inner stops of the two sets of ear plate seats (84) and is hinged through the shaft (83). The plug plate I (82) and the plug plate II (86) are both two-step semi-circular plates, which are fixed to the drill tip plate I (81) and the drill tip plate II (87) respectively. The drill tip plate I (81) Both the drill tip plate Ⅱ (87) and the drill tip plate Ⅰ (81) are half of the whole drill tip plate. The drill tip plate Ⅰ (81) has a groove C at its end face and the drill tip plate Ⅱ (87) has a protrusion D at its corresponding end face. The drill tip plate Ⅰ (81) with the plug plate Ⅰ (82) and the drill tip plate Ⅱ (87) with the plug plate Ⅱ (86) rotate around the axis (83) respectively to close or open the lower port of the core tube (41). The groove C and the protrusion D are fitted together. The plug plate Ⅰ (82) and the plug plate Ⅱ (86) form a complete circle. The small diameter protrusions of the plug plate Ⅰ (82) and the plug plate Ⅱ (86) are circumferentially positioned with the inner hole at the lower end of the core tube (41).

6. A method for constructing composite piles, characterized in that, Using the construction apparatus according to any one of claims 1-5, the construction method includes the following steps: 1) Assemble the construction pile driver and install the power head device (10), concrete conversion reducer (20), transition reducer (30), drill bit (40), inner tube (50), inner tube moving device (60), enlarged diameter device (70) and double-opening drill tip device (80); the inner tube moving device (60) is connected to the pile driver hydraulic control device through a high-pressure oil pipe, the concrete conveying pump is connected to the concrete conversion reducer (20) through a concrete conveying pipe, the enlarged diameter device is in the retracted state, the double-opening drill tip device is in the closed state, the drill tip is aligned with the pile hole position, and the drill bit is straightened; 2) Start the pile driver and power head device. The power head device drives the drill bit to rotate in the downward drilling direction. Under the action of the rotating drill bit, some of the soil at the pile hole position is squeezed into the pile hole wall, and the remaining soil is transported to the ground surface outside the hole through the spiral blades on the rotating drill bit. Part of the squeezed soil is drilled to the design depth of the composite pile outer pile. 3) Drilling, grouting concrete, and inserting internal piles; 4) Using the internal pile driving equipment, apply vertical pressure to the partially exposed internal piles and drive the internal piles downwards until the top height of the internal pile meets the design pile top elevation of the composite pile, thus completing the construction of one composite pile.

7. The composite pile construction method according to claim 6, characterized in that, Step 3) includes the following steps: Keep the drill bit (40) rotating, first press concrete into the bottom of the drill bit's inner cavity, then slowly lift the drill bit, the concrete presses open the double-opening drill tip device (80), presses into the bottom of the outer pile hole, forming a 500-1000mm concrete column section (102); start the hydraulic control system, push the inner tube (50) down through the inner tube moving device (60), drive the enlarged diameter device (70) to open, the enlarged diameter device (70) rotates to squeeze the soil and expand the diameter, the enlarged diameter cavity formed is filled with the press-filled concrete, the soil that is not squeezed into the hole wall during the soil squeezing and enlarging process is transported from bottom to top along the spiral blades of the rotating drill bit under the action of the press-filled concrete at its bottom, lift the drill, expand the diameter, press-fill to the top elevation of the first enlarged body section (101), lift the inner pile (90) through the lifting device, penetrate the inner cavity of the inner tube (50), place the inner pile (90) in the concrete at the bottom of the drill bit's inner cavity by its own weight, remove the lifting device, and start again. The hydraulic control system, through the inner tube moving device (60), pulls the inner tube (50) upward, drives the enlarging diameter device (70) to close, and simultaneously starts drilling and pressure grouting to form a column section (102), until the bottom elevation of the second enlarged section (101) is reached, then drives the enlarging diameter device (70) to open again, continues drilling, enlarging, and pressure grouting to form an enlarged section (101), until the top elevation of the second enlarged section (101) is reached, thus forming the second column section (102) and the first... The core of both enlarged sections (101) is an inner pile (90); the construction of the column section (102) and the enlarged section (101) is repeated in sequence until the top elevation of the concrete outer pile (100) is reached. The resulting concrete outer pile (100) is wrapped around the inner pile (90) in the center, and some of the inner pile (90) is exposed above the top of the cast-in-place concrete outer pile (100), and the top of the exposed inner pile (90) is higher than the design elevation of the top of the composite pile.

8. The composite pile construction method according to claim 6, characterized in that, Step 3) includes the following steps: Keep the drill bit (40) rotating, first press concrete, and at the same time start the hydraulic control system. Drive the enlarging diameter device (70) to open through the inner tube moving device (60), and then slowly lift the drill bit. The concrete presses open the double-opening drill tip device (80) and presses it into the bottom of the outer pile hole and the enlarging diameter cavity to form the first enlarged body section (101). Then start the inner tube moving device (60) to drive the enlarging diameter device to retract, lift the drill and press concrete to form a column section (102). Stop lifting the drill and pressing concrete, lift the inner pile (90) through the lifting device, pass through the inner cavity of the inner tube (50), and place it in the concrete of the inner cavity at the bottom of the drill bit by the weight of the inner pile (90). Remove the lifting device and drive the enlarging diameter device (70) to open again. Start drilling, expand the diameter, and pressurize until the top elevation of the second enlarged section (101) is reached. Start the retraction device (70) and continue drilling and pressurizing until the top elevation of the column section (102) is reached. The core of the second enlarged section (101) and the second column section (102) formed are both inner piles (90). Repeat the construction of the enlarged section (101) and the column section (102) in sequence until the top elevation of the concrete outer pile (100) is reached. The formed concrete outer pile (100) is wrapped around the inner pile (90) in the center, and some of the inner pile (90) is exposed above the top of the cast-in-place concrete outer pile (100). The top of the exposed inner pile (90) is higher than the design elevation of the top of the composite pile.

9. A composite pile formed according to the pile construction method described in claim 6, 7 or 8, characterized in that, The composite pile structure includes an inner pile (90) and an outer pile (100), wherein the inner pile (90) is wholly or partially enclosed by the outer pile (100) within its length range; the inner pile (90) is a prestressed concrete pile or a steel pile; the outer pile (100) is made of superfluid concrete with a slump of 160-240mm, including an enlarged section (101) and a column section (102); the enlarged section (101) of the outer pile (100) is provided with one or two or more, located at the bottom and / or middle and / or top of the outer pile; if the maximum outer diameter or the maximum diagonal dimension of the cross section of the inner pile (90) is d, and the outer diameter of the enlarged section (101) is D, then: D≥1.5d.

10. A composite pile according to claim 9, characterized in that, The superfluid concrete is fine stone concrete or fine aggregate concrete with a concrete strength grade of C15, C20, C25 or C30.

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