Steel-concrete combined pipe pile and construction method thereof

Abstract

The invention relates to the technical field of precast piles, and particularly discloses a steel-concrete combined pipe pile and a construction method thereof. The steel-concrete combined pipe pile comprises a prefabricated pipe pile, a steel pipe pile and a pile feeder, the prefabricated pipe pile is a hollow pipe pile penetrating in the vertical direction. Two pile cap plates are arranged at the bottom of the prefabricated pipe pile; the two pile cap plates are hinged to the two sides of the prefabricated pipe pile correspondingly. The two pile cap plates are used for sealing the bottom of the prefabricated pipe pile in the process of sinking the prefabricated pipe pile into a soil layer; positioning notches are formed in the tops of the steel pipe piles; the pile feeder comprises a plurality of pile feeding sections; a threaded concave step is arranged at the bottom of the pile feeding section, and a threaded convex step is arranged at the top of the pile feeding section; the threaded convex step is used for clamping the threaded concave step or the positioning notch; the pile feeding section is used for connecting the hooping device and the steel pipe pile. The bearing capacity of the pipe pile can be improved through the steel pipe pile, the long-term bearing capacity of the constructed steel pipe pile can be calculated through the final pressure value, and calculation is convenient.

Description

Technical Field

[0001] The present application relates to the technical field of precast piles, and in particular to a steel-concrete composite pipe pile and a construction method thereof. Background Art

[0002] In the field of building pile foundations, high-strength prefabricated pipe piles prefabricated in factories are gradually being used in various types of buildings because of their advantages such as high pile body strength, stable quality, high single pile bearing capacity, short construction period and low cost. In actual pipe pile sinking construction, complex geological conditions with interlaced distribution of soft and hard strata are often encountered. When the pile end encounters hard interlayers or boulders that are difficult to penetrate, continued hammering or static pressure on the pipe pile is very likely to cause adverse consequences such as cracking of the pile body and crushing of the pile head. In addition, the pile end cannot reach the better bearing soil layer required by the design, which leads to insufficient vertical compressive bearing capacity of the pipe pile single pile foundation.

[0003] Moreover, when the prefabricated pipe piles cannot be sunk to the preset depth, they will have to be cut, which will lead to the loss of prestress in the prefabricated pipe piles themselves, making it impossible to give full play to the advantages of the high-strength pile body of the prefabricated pipe piles. In addition, when encountering areas with large stratum fluctuations or soft geology, it is possible that the prefabricated pipe pile foundation after construction according to the design plan will also have the problem of bearing capacity not meeting the design requirements. At this time, it is also necessary to improve the vertical compressive bearing capacity of the single pile of the prefabricated pipe piles that have been constructed.

[0004] In order to solve the above problems, patent CN113882361A - A steel pipe-reinforced concrete composite pile, proposed a new pile type composed of an upper steel pipe pile, a middle steel pipe outer concrete pile and a lower reinforced concrete pile, which is mainly used for temporary support structures with high bearing capacity required in deep soft soil or water environment, and has the characteristics of convenient construction and dismantling. This method is suitable for soft soil, but cannot be used to improve the bearing capacity of prefabricated pipe piles that have been constructed.

[0005] Patent CN102518133A-A prestressed hollow pipe pile follower sleeve pile sinking method proposes a method of sleeve a steel sleeve with an inner diameter larger than the prefabricated pipe pile on the top of the prefabricated pipe pile, and the steel sleeve is pressed into the construction stratum together with the prefabricated pipe pile, and the steel sleeve is disconnected from the prefabricated pipe pile after being pressed into the soil for a certain depth, and no longer sinks. Since the top of the prefabricated pipe pile is usually lower than the ground elevation, this construction plan mainly solves the problem that the pile foundation bearing capacity detection requires re-excavation of the foundation pit to expose the pile top, resulting in a long detection cycle, but it is also not helpful for improving the bearing capacity of the prefabricated pipe pile after construction. Summary of the invention

[0006] The purpose of the present application is to provide a steel-concrete composite pipe pile and a construction method thereof, which is used to solve the problems of existing prefabricated piles such as difficulty in sinking piles in hard strata, pile cutting due to length not meeting the preset depth, and insufficient bearing capacity after construction in softer soil layers.

[0007] In order to achieve the above technical purpose, the first aspect of the present application provides a steel-concrete composite pipe pile, including: a prefabricated pipe pile, a steel pipe pile and a pile driver;

[0008] The prefabricated pipe pile is a hollow pipe pile that penetrates in the vertical direction;

[0009] Two pile cap plates are arranged at the bottom of the prefabricated pipe pile;

[0010] The two pile cap plates are hinged to two sides of the prefabricated pipe pile respectively;

[0011] The two pile cap plates are used to seal the bottom of the prefabricated pipe pile during the process of sinking the prefabricated pipe pile into the soil layer;

[0012] A positioning notch is provided on the top of the steel pipe pile;

[0013] The pile driver comprises: a plurality of pile driving sections;

[0014] The top of the pile delivery section is provided with a threaded concave step, and the bottom of the pile delivery section is provided with a threaded convex step;

[0015] The thread convex step is used to engage with the thread concave step or the positioning notch;

[0016] The pile delivery section is used to connect the clamp and the steel pipe pile, and is driven by the thrust of the clamp to press the steel pipe pile down until part of the steel pipe pile is located in the prefabricated pipe pile and another part of the steel pipe pile is pressed into a strong bearing layer of a preset depth.

[0017] Furthermore, a metal corrugated tube is provided on the inner wall of the bottom end of the prefabricated pipe pile.

[0018] Furthermore, the steel pipe pile is a hollow steel pipe;

[0019] The outer circumference of the steel pipe pile is provided with a plurality of reinforcing ribs evenly distributed around the circumference;

[0020] The reinforcing rib penetrates the steel pipe pile along the axial direction of the steel pipe pile.

[0021] Furthermore, a plurality of shear keys evenly distributed around the circumference are provided on the outer wall of the steel pipe pile;

[0022] The shear key is at least arranged at the top end of the steel pipe pile.

[0023] Furthermore, a pile tip is provided at the bottom end of the steel pipe pile;

[0024] The pile tip is in a bullet shape or a cross shape.

[0025] Furthermore, the pile driver further comprises: a pile-holding transition block;

[0026] The pile-holding transition block is used to be detachably mounted on the top end of the pile-delivering section to increase the diameter of the pile-delivering section.

[0027] Furthermore, the pile driver further comprises: a pile pressing assembly;

[0028] The pile driving assembly comprises: a main frame, an oil cylinder and a sliding block;

[0029] The main frame is installed on the top of the prefabricated pipe pile;

[0030] The main frame is used for the steel pipe piles and the pile delivery section to pass through;

[0031] The sliding block is slidably disposed on the main frame along a vertical direction;

[0032] The oil cylinder is arranged on the main frame, and the output end of the oil cylinder is connected to the sliding block, so as to drive the sliding block to press down the pile delivery section.

[0033] Furthermore, the main frame includes: an upper base, a lower base and a plurality of guide rods;

[0034] The top end of the guide rod is connected to the upper base;

[0035] The bottom end of the guide rod is connected to the lower base;

[0036] A plurality of guide rods are arranged at intervals;

[0037] The sliding block is slidably sleeved on the plurality of guide rods along the vertical direction.

[0038] Furthermore, a lifting eye threaded hole is provided on the top of the steel pipe pile.

[0039] A second aspect of the present application provides a construction method for a steel-concrete composite pipe pile, which is applied to any of the above-mentioned steel-concrete composite pipe piles and comprises the following steps:

[0040] S1, pressing the prefabricated pipe pile down to a first preset depth;

[0041] S2, after the steel pipe pile is lowered into the prefabricated pipe pile, the threaded convex step of the pile delivery section is butted against the positioning notch of the steel pipe pile;

[0042] S3, pressing the pile delivery section downward until part of the steel pipe pile is located inside the prefabricated pipe pile and another part of the steel pipe pile is pressed into a strong bearing layer at a preset depth;

[0043] S4, pouring concrete into the overlapping section of the prefabricated pipe pile and the steel pipe pile;

[0044] S5. Calculate the long-term bearing capacity Q of the steel pipe pile.

[0045] Furthermore, the step S5 comprises:

[0046] S51, measuring the final pressure value P of the steel pipe pile when it is pressed down;

[0047] S52, calculating the long-term bearing capacity Q of the steel pipe pile, where the long-term bearing capacity Q is the bearing capacity value of the steel pipe pile 30 days after the construction is completed;

[0048] Among them, when the steel pipe pile is in a non-cohesive soil layer with a stratum permeability coefficient k higher than 1m / d, the calculation formula of the long-term bearing capacity Q is: Q=α*P, where α is the bearing capacity correction factor, which is converted from the static load data of the same specification foundation piles at the construction site or obtained from the experience in the same stratum area;

[0049] When the steel pipe pile is in a non-cohesive soil layer with a stratum permeability coefficient k lower than 1 m / d, the calculation formula of the long-term bearing capacity Q is: Q=P(1+β), where β is the long-term bearing capacity recovery coefficient;

[0050] The calculation formula of β is:

[0051] .

[0052] It can be seen from the above technical scheme that the present application provides a steel-concrete composite pipe pile and a construction method thereof; wherein, a steel-concrete composite pipe pile comprises: a prefabricated pipe pile, a steel pipe pile and a pile driver; the prefabricated pipe pile is a hollow pipe pile that passes through in the vertical direction; two pile cap plates are arranged at the bottom of the prefabricated pipe pile; the two pile cap plates are respectively hinged to the two sides of the prefabricated pipe pile; the two pile cap plates are used to close the bottom of the prefabricated pipe pile during the process of sinking the prefabricated pipe pile into the soil layer; a positioning notch is arranged at the top of the steel pipe pile; the pile driver comprises: a plurality of pile driving sections; a threaded concave step is arranged at the top of the pile driving section, and a threaded convex step is arranged at the bottom of the pile driving section; the threaded convex step is used to clamp the threaded concave step or the positioning notch; the pile driving section is used to connect the clamp and the steel pipe pile, and driven by the thrust of the clamp to press the steel pipe pile down to a strong bearing layer in which a part of the steel pipe pile is located in the prefabricated pipe pile and another part of the steel pipe pile is pressed into a preset depth.

[0053] In addition, because the diameter of steel pipe piles is smaller than that of precast pipe piles, and the steel pile body has high strength and rigidity, combined with the pile tip with ground-breaking ability, steel pipe piles have the ability to break through rocks or hard interlayers. During the construction process, when precast pipe piles encounter hard interlayers or boulders, the hard interlayers can be broken by driving steel pipe piles into the precast pipe piles, allowing the precast pipe piles to be pressed down smoothly; at the same time, the pressing depth of the steel pipe piles can be adjusted to strengthen the overall pressing depth of the piles, avoiding the need to cut the precast pipe piles; in addition, the bearing capacity of the precast pipe piles can be increased by using steel pipe piles, avoiding the situation where the bearing capacity is insufficient in soft soil layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0055] Figure 1 A cross-sectional view of the overall structure of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0056] Figure 2 A cross-sectional view of a prefabricated pipe pile of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0057] Figure 3 A schematic diagram of a steel pipe pile of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0058] Figure 4 for Figure 1 A magnified view of part A in FIG.

[0059] Figure 5 A schematic diagram of multiple pile delivery sections of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0060] Figure 6 A side cross-sectional view of the pile head of a steel-concrete composite pipe pile provided in an embodiment of the present application when the prefabricated pipe pile is placed horizontally;

[0061] Figure 7 A top view of a pile head of a steel-concrete composite pipe pile provided in an embodiment of the present application when the prefabricated pipe pile is placed horizontally;

[0062] Figure 8 A schematic diagram of the connection between the pile delivery section and the pile holding transition block of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0063] Fig. 9A side cross-sectional view of a pile-holding transition block of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0064] Fig.10 A top view of a pile-holding transition block of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0065] Fig.11 A cross-sectional view of the overall structure of a steel-concrete composite pipe pile provided in another embodiment of the present application;

[0066] Fig.12 A schematic diagram of a pile cap of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0067] Fig.13 for Fig.11 A magnified view of part B in FIG.

[0068] Fig.14 A cross-sectional view of the overall structure of a steel-concrete composite pipe pile provided in another embodiment of the present application;

[0069] Fig.15 A schematic diagram of the connection between a pile driving assembly and a prefabricated pipe pile of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0070] Fig.16 A schematic diagram of a main frame in a pile driving assembly of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0071] Fig.17 A schematic diagram of a slider of a pile driving assembly of a steel-concrete composite pipe pile provided in an embodiment of the present application;

[0072] Fig.18 A schematic diagram of the calculation of the bearing capacity of a steel pipe pile of a pile driving assembly of a steel-concrete composite pipe pile provided in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the specification of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection requested by the present application.

[0074] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0075] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a replaceable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0076] See also Figure 1 In a first aspect, a steel-concrete composite pipe pile is provided in an embodiment of the present application, comprising: a prefabricated pipe pile 1, a steel pipe pile 2 and a pile driver 3.

[0077] See also Figure 2 The prefabricated pipe pile 1 is a hollow pipe pile that penetrates in the vertical direction. Two pile cap plates 11 are arranged at the bottom of the prefabricated pipe pile 1; the two pile cap plates 11 are hinged to the two sides of the prefabricated pipe pile 1 respectively.

[0078] Specifically, the prefabricated pipe pile 1 is divided into a pile body 101 and a pile head 102; when driving the pile, the pile head 102 is pressed into the soil layer before the pile body 101, so after driving the pile, the pile head 102 is located below the pile body 101; the bottom end of the pile head 102 is the bottom end of the prefabricated pipe pile 1. The pile head 102 is a prefabricated part, and the outer diameter of the pile head 102 is the same as the outer diameter of the pile body 101. The pile head 102 can be made of ultra-high performance concrete (UHPC).

[0079] The two pile cap plates 11 are used to seal the bottom of the prefabricated pipe pile 1 during the process of sinking the prefabricated pipe pile 1 into the soil layer to prevent soil from entering the prefabricated pipe pile 1 .

[0080] See also Figures 3 to 5 A positioning notch 21 is provided on the top of the steel pipe pile 2.

[0081] The pile driver 3 comprises: a plurality of pile driving sections 31; a threaded concave step 32 is provided at the top of the pile driving section 31, and a threaded convex step 33 is provided at the top of the pile driving section 31; the threaded convex step 33 is used to clamp the threaded concave step 32 or the positioning notch 21; the pile driving section 31 is used to connect the clamp and the steel pipe pile 2, and driven by the thrust of the clamp to press the steel pipe pile 2 down to a strong bearing layer where part of the steel pipe pile 2 is located in the prefabricated pipe pile 1 and the other part of the steel pipe pile 2 is pressed into a preset depth.

[0082] The uppermost end of the steel pipe pile 2 is provided with a lifting ring threaded hole 25. The lifting ring threaded hole 25 is used for lifting by a crane, and after the steel pipe pile 2 is lifted into the inner hole of the prefabricated pipe pile 1, the lifting ring connected to the lifting ring threaded hole 25 can be removed. The threaded convex step 33 at the lower end of the pile delivery section 31 can have two structures, such as Figure 5 As shown, the threaded convex step 33 of the pile delivery section 31 used to connect the steel pipe pile 2 is relatively long and can extend into the threaded hole 25 of the lifting ring; the threaded convex step 33 of the pile delivery section 31 used to connect the pile delivery section 31 is relatively short and is used to clamp the threaded concave step 32.

[0083] In order to improve the connection strength between the prefabricated pipe pile 1 and the steel pipe pile 2, a metal bellows 12 is provided on the inner wall of the pile head 102. The minimum inner diameter of the metal bellows 12 is 1.0 to 1.2 times the inner diameter of the pile body to prevent the steel pipe pile 2 from getting stuck at the pile head 102 during subsequent construction.

[0084] See also Figure 2 , Figure 6 and Figure 7 In the inner wall of the pile head 102 and the pile body 101, a corresponding number of channels 103 are evenly distributed along the axis; the channels 103 serve as prestressed steel strand channels of the prefabricated pipe pile 1; a circular hole is provided on the pile cap plate 11; the circular hole is connected to the channel 103.

[0085] When manufacturing the prefabricated pipe pile 1, the steel strands are passed through the hole and the circular hole in sequence, and then the prestressing force is applied to manufacture the pipe pile.

[0086] To prevent concrete from entering the metal bellows 12 during the centrifugal process, rubber blocks or foam can be filled inside the pile head 102. To improve the integrity of the connection between the pile head 102 and the pile body 101, the bottom end surface of the pile head 102 needs to be roughened before the pile body is made.

[0087] The two pile cap plates 11 are two semicircular steel plates. The two pile cap plates 11 are connected to the pile head end plate 105 through a pile cap shaft pin 104. When the prefabricated pipe pile 1 is pressed, the two pile cap plates 11 abut against each other and close to prevent soil from entering the interior of the pipe pile.

[0088] When the steel pipe pile 2 is pressed in, the two pile cap plates 11 rotate along the axle pin under the force of the steel pipe pile 2, and the two pile cap plates 11 open to both sides, which will not hinder the steel pipe pile 2 from being pressed into the lower soil.

[0089] In one embodiment, the steel pipe pile 2 is a hollow steel pipe; a plurality of reinforcing ribs 22 evenly distributed around the periphery of the steel pipe pile 2 are provided; and the reinforcing ribs 22 penetrate the steel pipe pile 2 along the axial direction of the steel pipe pile 2. The reinforcing ribs 22 of the steel pipe pile 2 can improve the lateral friction resistance of the steel pipe pile 2 on the one hand, and can improve the bending resistance of the steel pipe pile 2 on the other hand. In addition, the reinforcing ribs 22 of the steel pipe pile 2 can play a guiding role in the pressing construction stage, effectively preventing the steel pipe pile from being pressed into the lower stratum of the prefabricated pipe pile by deflection.

[0090] The maximum outer diameter of the steel pipe pile 2 is smaller than the hollow inner diameter of the prefabricated pipe pile 1. Four to six reinforcing ribs 22 are provided and are welded and arranged along the axial length of the steel pipe pile 2.

[0091] In one embodiment, a pile tip 23 is disposed at the bottom end of the steel pipe pile 2; the pile tip 23 is in a bullet-shaped or cross-shaped shape to enhance the ground-breaking capability and reduce the pressure resistance.

[0092] In one embodiment, a plurality of shear keys 24 evenly distributed around a circumference are disposed on the outer wall of the steel pipe pile 2 ; the shear keys 24 are at least disposed at the top end of the steel pipe pile 2 .

[0093] The shear keys 24 are evenly arranged along the circumference of the steel pipe pile and extend a certain length downward from the upper end of the steel pipe pile along the axial direction.

[0094] In order to ensure that the steel pipe pile 2 can smoothly pass through the inner hole of the prefabricated pipe pile 1 and the prefabricated pipe pile 1 can play a good role in straightening the steel pipe pile, the inner wall smoothness and inner diameter size of the prefabricated pipe pile 1 must be strictly required during production. Therefore, after the prefabricated pipe pile 1 is made, the inner wall of the prefabricated pipe pile 1 needs to be inspected, and the prefabricated pipe pile 1 that does not meet the requirements needs to be processed through the hole. The through-hole method is that the motor-driven grinding head rotates back and forth inside the pipe pile until the inner diameter and smoothness meet the requirements. 3 to 6 nozzles are evenly arranged on the grinding head, and the nozzles can spray coolant to play a role in cooling and chip removal. A spiral groove is opened on the grinding head to provide a channel for the discharge of grinding chips and the flow of coolant.

[0095] In one embodiment, the steel pipe pile 2 can be pressed in by holding the pile delivery section 31 through the clamp of the static pile driver, and pushing the steel pipe pile 2 into a certain distance below the bottom of the prefabricated pipe pile 1, and leaving a portion of the upper part of the steel pipe pile 2 with the shear key 24 in the prefabricated pipe pile 1. The pile delivery section 31 is composed of a single relatively long hollow steel pipe or solid steel rod, and its diameter is smaller than the inner diameter of the prefabricated pipe pile 1.

[0096] See also Figures 8 to 10 When the minimum diameter of the clamp of the static pile driver used to construct the prefabricated pipe pile 1 is larger than the diameter of the pile delivery section 31 , the pile delivery section 31 needs to be additionally provided with a pile-holding transition block 34 .

[0097] The pile holding transition block 34 is used to be detachably mounted on the top of the pile delivery section 31 to increase the diameter of the pile delivery section 31. The pile holding transition block 34 is a structure composed of two semicircular rings 343, wherein bolt through holes 341 are provided on both sides of one semicircular ring 343, and a threaded hole 342 is provided on the other semicircular ring 343. The two semicircular rings 343 are fixed to the pile delivery section 31 by bolt connection. At the same time, a pin hole 39 may be provided on the pile delivery section 31 for a solid steel rod to be inserted to connect the pile holding transition block 34 and the pile delivery section 31.

[0098] Since the distance that the clamp of the static pile driver can press in at one time is limited, inserting a steel pipe pile 2 of more than ten meters or even longer into the soil requires the clamp to move back and forth several times to completely drive the steel pipe pile 2 into the soil layer. Therefore, when the diameter of the pile-holding transition block 34 is larger than the inner diameter of the prefabricated pipe pile 1, the pile-holding transition block 34 needs to be disassembled after each stroke of the static pile driver.

[0099] For the convenience of construction, a plurality of pile holding transition blocks 34 are arranged at a certain length on the upper end of the pile delivery section 31. During the downward pressing process of the pile driver, a pile holding transition block 34 is disassembled at the end of each clamp stroke. After the steel pipe pile 2 is pressed in, the pile delivery section 31 is lifted out of the inner hole of the prefabricated pipe pile 1.

[0100] The steel pipe pile 2 is pressed in by multiple pile driving sections 31, i.e., a multi-section pile driving device; two pile driving sections 31 are mechanically connected. During construction, the first pile driving section 31 is gradually lowered to contact the upper end of the steel pipe pile 2, and then multiple pile driving sections 31 are lowered respectively. When the upper end of the pile driving section 31 is higher than the ground, the pile cap 4 is installed on the upper end of the pile driving section 31. Figures 11 to 13 The pile cap 4 is provided with a step hole 41, and the pile delivery section 31 can be stuck in the step hole 41 to prevent the pile delivery section 31 from deflecting. When the pile delivery section 31 is hoisted, the pile cap 4 can be hoisted to pull out the pile delivery section 31.

[0101] The upper end of the pile cap 4 is in face-to-face contact with the clamp of the static press. During the downward pressing process of the clamp, the pile driving section 31 presses the steel pipe pile 2 into the ground. When the upper end of the pile driving section 31 is close to the ground, a new section of the pile driving section 31 is connected, and the process is repeated alternately until the steel pipe pile 2 is pressed to a specified depth. Finally, the pile driving section 31 is lifted out of the inner hole of the prefabricated pipe pile 1 as a whole.

[0102] like Fig.13 As shown, the lower end of the pile delivery section 31 is provided with a threaded convex step 33, and the upper end is provided with a threaded concave step 32. When connected, the threaded convex step 33 of the upper pile delivery section 31 is inserted into the threaded concave step 32 of the lower pile delivery section 31, and the mechanical connection is achieved by tightening the thread. It should be noted that the convex step at the lower end of the first pile delivery section 31 is not provided with a thread, and is non-fixedly connected to the upper end of the steel pipe pile 2. The upper and lower ends of the pile delivery section 31 are provided with a pin through hole 310, which can be used to insert a solid steel rod to tighten and disassemble the multi-stage pile delivery device.

[0103] In another embodiment, the steel pipe pile 2 may be pressed into the designed depth by hammering, such as Fig.14 As shown. The end face of the steel pipe pile 2 is a stepped hole corresponding to the boss of the rammer 5. The steel pipe pile 2 is buried to a specified depth by inserting the rammer 5 into the inner hole of the prefabricated pipe pile 1 to hammer the upper end face of the steel pipe pile. The depth of the steel pipe pile 2 entering the stratum is determined by measuring the depth of the rammer 5 descending. After the construction is completed, the rammer 5 is lifted off the bottom of the hole.

[0104] In one embodiment, the steel pipe pile 2 is pressed in by using a lightweight pile pressing assembly 35. Figures 15 to 17 As shown, the pile driving assembly 35 includes: a main frame 36, a cylinder 37 and a slider 38; the main frame 36 is installed on the top of the prefabricated pipe pile 1; the main frame 36 is used for the steel pipe pile 2 and the pile delivery section 31 to pass through; the slider 38 is slidably arranged on the main frame 36 along the vertical direction; the cylinder 37 is arranged on the main frame 36, and the output end of the cylinder 37 is connected to the slider 38, which is used to drive the slider 38 to press the pile delivery section 31 downward.

[0105] Furthermore, the main frame 36 includes: an upper base 361, a lower base 362 and a plurality of guide rods 363; the top end of the guide rod 363 is connected to the upper base 361; the bottom end of the guide rod 363 is connected to the lower base 362; the plurality of guide rods 363 are arranged at intervals; and the slider 38 can be slidably sleeved on the plurality of guide rods 363 along the vertical direction.

[0106] The upper base 361 and the lower base 362 are both provided with a central hole 364 for the steel pipe pile 2 or the pile delivery section 31 to pass through. The lower base 362 is provided with evenly distributed bolt holes 365, and the main frame 36 can be connected and fixed to the end plate of the prefabricated pipe pile 1 by bolts. The upper base 361 is provided with a cylinder hanging ear 366 for fixing the cylinder 37. A semicircular hole is provided on the side of the cylinder hanging ear 366 on the upper base 361 for installing the cylinder 37.

[0107] The slider 38 is made of thick steel plate, and is provided with guide holes 381 corresponding to the guide rod 363 on all sides. The slider 38 can move up and down on the guide rod 363; the slider 38 is provided with a fixed ear seat 382 for connecting the oil cylinder 37, and there is a large round hole in the middle to facilitate the placement of the pile delivery section 31. When the pile delivery section 31 needs to be pressed, it is achieved by installing a pile cap 4 under the slider 38, and the pile cap 4 is removable. During construction, due to the limited stroke of the oil cylinder 37, multiple pile delivery sections 31 are used to press the steel pipe pile 2 into the formation. After the oil cylinder 37 extends downward, it pushes the slider 38 to move downward and press the pile delivery section 31 downward. After the stroke is completed, the oil cylinder 37 retracts and connects another pile delivery section 31, and repeats the pile pressing action until the steel pipe pile 2 is pressed into the specified depth.

[0108] A second aspect of the present application provides a construction method of a steel-concrete composite pipe pile, which is applied to any one of the above-mentioned steel-concrete composite pipe piles and comprises the following steps:

[0109] S1. Press the prefabricated pipe pile 1 down to a first preset depth.

[0110] The prefabricated pipe pile 1 can be constructed by static pressure or hammering. After the prefabricated pipe pile is constructed to a predetermined depth, the pile top needs to be covered with a pile end cover plate or other plugging material to block the pile top of the prefabricated pipe pile 1 to prevent objects from falling into the internal cavity of the prefabricated pipe pile 1 during construction, which would affect subsequent construction, especially when the pile top height of the prefabricated pipe pile 1 after construction is lower than the surface soil height on site.

[0111] S2, after the steel pipe pile 2 is lowered into the prefabricated pipe pile 1, the threaded protruding step 33 of the pile delivery section 31 is butted against the positioning notch 21 of the steel pipe pile 2.

[0112] Specifically, after the construction of the prefabricated pipe pile 1 is completed, the sealing material on the top of the prefabricated pipe pile 1 is removed, and the steel pipe pile 2 is lowered into the inner cavity of the prefabricated pipe pile 1; the total length of the steel pipe pile 2 is longer than the length of the prefabricated pipe pile 1, and after the steel pipe pile 2 is lowered into the prefabricated pipe pile 1, the upper end is at least 0.5m above the ground, which is convenient for connecting the pile delivery section 31.

[0113] S3, pressing the pile section 31 downward until part of the steel pipe pile 2 is located inside the prefabricated pipe pile 1 and the other part of the steel pipe pile 2 is pressed into a strong bearing layer at a preset depth.

[0114] After the steel pipe pile 2 is lowered into the inner hole of the prefabricated pipe pile 1, the pile delivery section 31 is used to apply force through the upper end of the steel pipe pile 2 to push the pile cap plate 11 away from the steel pipe pile 2, and continue to push downward until the lower end of the steel pipe pile 2 enters the designed strong bearing layer or a predetermined depth. During the downward pushing process of the steel pipe pile 2, a new steel pipe pile 2 needs to be welded and connected according to the designed depth.

[0115] For steel pipe piles 2 that need to be welded in multiple sections, after the steel pipe piles 2 are pressed into the required position, the section of the steel pipe pile 2 where the shear key 24 is arranged must be at the uppermost end of the steel pipe pile 2 as a whole, and the section where the shear key 24 is arranged must be in the inner hole of the prefabricated pipe pile 1, and have an overlapping section with the pile head 102 of the prefabricated pipe pile 1.

[0116] S4, pouring concrete into the prefabricated pipe pile 1 and the steel pipe pile 2.

[0117] After the steel pipe pile 2 is pressed in, concrete is poured into the gap between the pile head 102 of the precast pipe pile 1 and the steel pipe pile 2. A certain height of concrete is also poured into the inner hole of the precast pipe pile 1 at the upper end of the steel pipe pile 2. After the precast pipe pile 1 is compressed, the steel pipe pile 2 can enhance the pile end bearing capacity of the precast pipe pile 1 through its own bearing capacity.

[0118] S5. Calculate the long-term bearing capacity Q of the steel pipe pile 2.

[0119] Specifically, step S5 includes:

[0120] S51, measuring the final pressure value P of the steel pipe pile 2 when it is pressed down;

[0121] S52, calculating the long-term bearing capacity Q of the steel pipe pile 2, where the long-term bearing capacity Q is the bearing capacity value of the steel pipe pile 2 30 days after the construction is completed;

[0122] Among them, when the steel pipe pile 2 is in a non-cohesive soil layer with a stratum permeability coefficient k higher than 1m / d, the calculation formula of the long-term bearing capacity Q is: Q=α*P, where α is the bearing capacity variation coefficient, which is converted from the static load data of the same specification foundation piles at the construction site or obtained from the experience in the same stratum area;

[0123] When the steel pipe pile 2 is in a non-cohesive soil layer with a stratum permeability coefficient k lower than 1m / d, the calculation formula of the long-term bearing capacity Q is: Q=α*P(1+β), where β is the long-term bearing capacity recovery coefficient;

[0124] The calculation formula of β is:

[0125] .

[0126] See also Fig.18 After the steel pipe pile 2 is finally pressed in, the final pressure value is recorded. The bearing capacity Q of the steel pipe pile 2 can be calculated based on the final pressure value P when the pile is pressed.

[0127] In one embodiment, a site is a silty clay stratum with a stratum permeability coefficient k of 0.05 m / d. The diameter of the prefabricated pipe pile 1 is 400 mm and the length is 12 m. After construction, the bearing capacity of the prefabricated pipe pile 1 is measured to be 800 kN, which does not meet the requirement that the design bearing capacity must reach 1000 kN. In order to improve the bearing capacity of the pipe pile, after the construction of the prefabricated pipe pile 1 is completed, the steel pipe pile 2 is pressed into the inner hole of the pipe pile. The diameter of the thin-walled steel pipe of the steel pipe pile 2 is 160 mm, the maximum diameter is 180 mm, the thickness of the reinforcing rib 22 is 10 mm, and it is pressed 10 m below the end of the prefabricated pipe pile. The final pressure value P of the steel pipe pile measured during the construction process is 310 kN.

[0128] Since the steel pipe pile 2 is constructed in a clay layer with a permeability coefficient of less than 1m / d, the long-term bearing capacity recovery coefficient β of the steel pipe pile 2 is calculated as 0.47 according to the above formula. The static load test data of the foundation piles at the same site show that the bearing capacity correction coefficient α of this site is 1.05. Therefore, the long-term bearing capacity of the steel pipe pile 2 can be obtained as 477kN according to the above formula. Therefore, the ultimate bearing capacity of the entire steel-concrete composite pipe pile after the steel pipe pile 2 and the prefabricated pipe pile 1 are combined is 1277kN, which effectively improves the bearing capacity of the pipe pile and meets the design requirements of the foundation pile.

[0129] Through the above design scheme, the present invention can bring the following beneficial effects:

[0130] (1) This solution can solve the problems of insufficient pile length and insufficient bearing capacity due to the difficulty or inability to sink prefabricated pipe piles 1 in complex strata such as hard interlayers and boulders. In particular, for piles with insufficient bearing capacity after the construction of prefabricated pipe piles 1, this solution can be used to enhance the bearing capacity of prefabricated pipe piles, thereby effectively remedying the piles that have been constructed.

[0131] (2) This solution can improve the connection strength between the steel pipe pile 2 and the pile head 102 through the specially made pile head 102, and effectively realize the reliable force transmission between the lower steel pipe pile 2 and the upper prefabricated pipe pile 1.

[0132] (3) This solution can be used to press the steel pipe pile 2 into the strong bearing layer or rock layer through the inner hole of the prefabricated pipe pile 1, which can effectively enhance the overall bearing capacity of the prefabricated pipe pile 1. Compared with pile end reinforcement processes such as rammed piles and carrier piles, this solution is not affected by groundwater at the pile end, significantly improving the construction success rate of water-rich soft soil layers.

[0133] (4) The steel pipe pile 2 of the technical solution can be pressed into place by various pile driving construction equipment such as static press, rammer and pile driving assembly 35, which is convenient for construction and can select a better construction scheme according to the existing equipment conditions at the construction site. The use of existing static press and other equipment on site can reduce construction costs. The use of simple pile driving equipment can use the constructed pipe piles as the reaction force structure, effectively reducing construction costs.

[0134] (5) The long-term bearing capacity of the steel pipe pile 2 of the present technical solution can be calculated by the final pressure value P, which is convenient for calculating the overall bearing capacity of the reinforced pile foundation and is more referenceable.

[0135] (6) The steel pipe pile 2 in this solution can extend into the rock layer, achieving the desired depth of pile sinking while further improving the overall bearing capacity.

[0136] (7) The steel pipe pile 2 can better control the overall depth of the reinforced pile, avoiding the need to cut the prefabricated pipe pile 1. For example, if the required pile depth is 30m, and the depth of a prefabricated pipe pile 1 is 10m, the existing construction method is to drive three prefabricated pipe piles 1. However, if a rock layer is found at 25m before construction, the three prefabricated pipe piles 1 can only be driven to 25m, so the third prefabricated pipe pile 1 needs to be cut by 5m, and the pile depth requirement cannot be met. However, through this solution, only two prefabricated pipe piles 1 can be driven, and then the pile depth can be controlled by driving the steel pipe pile 2.

[0137] The above are only preferred embodiments of the present application and are not intended to limit the present invention. Although the present application has been described in detail with reference to the examples, those skilled in the art can still modify the technical solutions recorded in the aforementioned examples or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A steel-concrete composite pipe pile, characterized in that: include: Prefabricated pipe piles (1), steel pipe piles (2) and pile drivers (3); The prefabricated pipe pile (1) is a hollow pipe pile that penetrates in the vertical direction; Two pile cap plates (11) are arranged at the bottom of the prefabricated pipe pile (1); The two pile cap plates (11) are respectively hinged to two sides of the prefabricated pipe pile (1); The two pile cap plates (11) are used to seal the bottom of the prefabricated pipe pile (1) during the process of sinking the prefabricated pipe pile (1) into the soil layer; A positioning notch (21) is provided at the top of the steel pipe pile (2); The pile driver (3) comprises: a plurality of pile driver sections (31); The top of the pile delivery section (31) is provided with a threaded concave step (32), and the bottom of the pile delivery section (31) is provided with a threaded convex step (33); The thread convex step (33) is used to engage with the thread concave step (32) or the positioning notch (21); The pile delivery section (31) is used to connect the clamp and the steel pipe pile (2), and is driven by the thrust of the clamp to press the steel pipe pile (2) downward until a portion of the steel pipe pile (2) is located inside the prefabricated pipe pile (1) and another portion of the steel pipe pile (2) is pressed into a strong bearing layer at a preset depth.

2. The steel-concrete composite pipe pile according to claim 1, characterized in that: The inner wall of the bottom end of the prefabricated pipe pile (1) is provided with a metal corrugated pipe (12).

3. The steel-concrete composite pipe pile according to claim 1, characterized in that: The steel pipe pile (2) is a hollow steel pipe; The outer circumference of the steel pipe pile (2) is provided with a plurality of reinforcing ribs (22) evenly distributed around the circumference; The reinforcing rib (22) penetrates the steel pipe pile (2) along the axial direction of the steel pipe pile (2).

4. The steel-concrete composite pipe pile according to claim 3, characterized in that: A plurality of shear keys (24) evenly distributed around the circumference are arranged on the outer wall of the steel pipe pile (2); The shear key (24) is at least arranged at the top end of the steel pipe pile (2).

5. The steel-concrete composite pipe pile according to claim 1, characterized in that: The bottom end of the steel pipe pile (2) is provided with a pile tip (23); The pile tip (23) is in the shape of a bullet head or a cross.

6. The steel-concrete composite pipe pile according to claim 1, characterized in that: The pile driver (3) further comprises: a pile-holding transition block (34); The pile-holding transition block (34) is used to be detachably mounted on the top end of the pile-delivering section (31) to increase the diameter of the pile-delivering section (31).

7. The steel-concrete composite pipe pile according to claim 1, characterized in that: The pile driver (3) further comprises: a pile pressing assembly (35); The pile driving assembly (35) comprises: a main frame (36), an oil cylinder (37) and a sliding block (38); The main frame (36) is installed on the top of the prefabricated pipe pile (1); The main frame (36) is used for allowing the steel pipe pile (2) and the pile delivery section (31) to pass through; The sliding block (38) is slidably disposed on the main frame (36) along a vertical direction; The oil cylinder (37) is arranged on the main frame (36), and the output end of the oil cylinder (37) is connected to the slider (38) for driving the slider (38) to press down the pile delivery section (31).

8. The steel-concrete composite pipe pile according to claim 7, characterized in that: The main frame (36) comprises: an upper base (361), a lower base (362) and a plurality of guide rods (363); The top end of the guide rod (363) is connected to the upper base (361); The bottom end of the guide rod (363) is connected to the lower base (362); A plurality of guide rods (363) are arranged at intervals; The sliding block (38) is slidably sleeved on the plurality of guide rods (363) along a vertical direction.

9. The steel-concrete composite pipe pile according to claim 1, characterized in that: A lifting ring threaded hole (25) is provided on the top of the steel pipe pile (2).

10. A construction method for steel-concrete composite pipe piles, characterized in that: The method is applied to the steel-concrete composite pipe pile according to any one of claims 1 to 9, and comprises the following steps: S1, pressing the prefabricated pipe pile (1) down to a first preset depth; S2, after the steel pipe pile (2) is lowered into the prefabricated pipe pile (1), the threaded convex step (33) of the pile delivery section (31) is butted against the positioning notch (21) of the steel pipe pile (2); S3, pressing the pile delivery section (31) downward until part of the steel pipe pile (2) is located inside the prefabricated pipe pile (1) and another part of the steel pipe pile (2) is pressed into a strong bearing layer at a preset depth; S4, pouring concrete into the overlapping section of the prefabricated pipe pile (1) and the steel pipe pile (2); S5. Calculate the long-term bearing capacity Q of the steel pipe pile (2).

11. The construction method of steel-concrete composite pipe pile according to claim 10, characterized in that: The step S5 comprises: S51, measuring the final pressure value P of the steel pipe pile (2) when it is pressed downward; S52, calculating the long-term bearing capacity Q of the steel pipe pile (2), wherein the long-term bearing capacity Q is the bearing capacity value of the steel pipe pile (2) 30 days after the construction is completed; Wherein, when the steel pipe pile (2) is in a non-cohesive soil layer with a stratum permeability coefficient k higher than 1 m / d, the calculation formula of the long-term bearing capacity Q is: Q=α*P, where α is a bearing capacity correction coefficient; When the steel pipe pile (2) is in a non-cohesive soil layer with a stratum permeability coefficient k lower than 1 m / d, the calculation formula of the long-term bearing capacity Q is: Q=α*P(1+β), where β is the long-term bearing capacity recovery coefficient; The calculation formula of β is: 。

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