Steel pile construction method suitable for permafrost regions
By combining steel pipe piles with sleeve structures, the problems of inaccurate positioning and loose bonding with coarse sand in steel pile construction in permafrost areas have been solved, realizing a simple and efficient construction method and improving pull-out resistance and construction efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA HYDROELECTRIC ENGINEERING CONSULTING GROUP CHENGDU RESEARCH HYDROELECTRIC INVESTIGATION DESIGN AND INSTITUTE
- Filing Date
- 2023-07-27
- Publication Date
- 2026-08-04
AI Technical Summary
In permafrost regions, traditional steel pile construction methods struggle to ensure accurate pile positioning and the loose bonding with the surrounding coarse sand results in significant frost heave and complex construction processes.
The steel pipe pile body and sleeve structure are used. The pile is squeezed into the soil by static pressure or hammering. The sleeve is pre-filled with coarse sand. After being pulled out, the gaps are automatically filled and compacted by hammering to ensure that the steel pile is centered and the coarse sand around the pile is dense.
It achieves precise positioning and simplified construction of steel piles, improves the compactness of the coarse sand around the piles, reduces the impact of frost heave, and reduces construction costs.
Smart Images
Figure CN116695704B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a steel pile construction method suitable for permafrost regions, belonging to the field of pile foundation engineering technology. Background Technology
[0002] High-altitude mountain sites are flat, open, with little obstruction and ample sunshine, making them suitable for photovoltaic projects. However, high-altitude mountain climates are cold and have high rainfall. Some sites are located on gentle slopes with high groundwater levels, resulting in significant frost heave. The main forms of permafrost damage at these sites include frost heave mounds, thaw sinkholes, frost-thaw grass mounds, and permafrost cracks.
[0003] Frozen soil foundations often experience frost heave and thaw settlement during freezing and thawing. Excessive freeze-thaw deformation can cause severe damage to buildings. When the foundation depth exceeds the freezing depth, tangential frost heave forces act on the sides of the foundation; when the foundation depth is shallower than the freezing depth, normal frost heave also acts on the bottom surface of the foundation. For soil foundations, traditional construction methods require pre-drilling a hole larger than the diameter of the steel pile, inserting the steel pile, and then perforating coarse sand around the pile. The high permeability of the coarse sand reduces the influence of pore water and groundwater, and lowers the impact of tangential frost heave forces. This construction method has two problems: 1. Because a larger diameter hole is pre-drilled, the coarse sand perforated around the pile does not bond as tightly; 2. It is difficult to ensure that the steel pile is centered after pre-drilling the hole. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a steel pile construction method suitable for permafrost areas, which can not only effectively ensure the positioning accuracy of the pile body, but also make the construction simpler and allow the coarse sand around the pile to be more tightly bonded.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a steel pile construction method applicable to permafrost areas. The steel pile structure includes a vertically arranged steel pipe pile body, with a coaxially arranged pile tip fixedly connected to the bottom end of the steel pipe pile body. The tip of the pile tip faces downward, and the outer edge of the top surface of the pile tip protrudes relative to the outer side wall of the bottom end of the steel pipe pile body to form an annular boss. A sleeve coaxial with the steel pipe pile body is fitted around the outer periphery. A slot for vertical insertion of the bottom end of the sleeve is provided on the annular boss. After the bottom end of the sleeve is inserted into the slot, the outer periphery of the steel pipe pile body, the inner periphery of the sleeve, and the surface of the annular boss combine to form a coarse sand receiving cavity. The top end of the sleeve is connected to the top end of the steel pipe pile body through a connecting positioning component. The connecting positioning component allows the top end of the sleeve and the top end of the steel pipe pile body to have a first state of relative connection and fixation and a second state of relative separation. The connecting positioning component and the steel pipe pile body are detachable. The construction process includes the following steps: Coarse sand is pre-filled into a coarse sand receiving cavity formed by the combination of the outer circumference of the steel pipe pile, the inner circumference of the sleeve, and the surface of the annular boss. The top of the sleeve is then connected and fixed to the top of the steel pipe pile using a connecting positioning component. The steel pipe pile and sleeve are driven into the soil to a set depth using static pressure or hammering. The connecting positioning component is then removed, and the sleeve is pulled out. During the pulling process, the coarse sand automatically fills the gaps around the outer circumference of the steel pipe pile. After the sleeve is pulled out, coarse sand is added to the top position to the design elevation, and then hammered to compact it. Preferably, during the pulling process, the sleeve is simultaneously tapped to assist in separating the coarse sand from the sleeve.
[0006] Furthermore, the main body of the pile tip is a hollow cylindrical structure, the upper diameter of the central through hole of the pile tip is equivalent to the inner diameter of the steel pipe pile body, and the lower side wall of the pile tip tapers into a sharp shape.
[0007] Furthermore, the main body of the pile tip is a hollow conical cylindrical structure with an upper diameter larger than the lower diameter.
[0008] Furthermore, before driving the piles, the surface of the pile tip is pre-coated with lubricant.
[0009] Furthermore, the top surface of the sleeve is not lower than the top surface of the steel pipe pile.
[0010] Furthermore, the connecting positioning component is a cap, and the lower surface of the cap has a first annular groove for vertical insertion of the top of the sleeve and a second annular groove for vertical insertion of the top of the steel pipe pile.
[0011] Furthermore, the lower surface of the cap has an annular boss that extends into the coarse sand receiving cavity, and the main body of the cap has a cap cavity with an open top. Several sand-flowing holes communicating with the coarse sand receiving cavity are provided in the area of the lower surface of the annular boss within the cap cavity. The top opening of the cap cavity is equipped with an openable and closable cover plate. During construction, after the cap is used to connect and fix the top of the sleeve to the top of the steel pipe pile, coarse sand is pre-filled in the cap cavity before pile driving.
[0012] Furthermore, the connecting positioning component is a snap-fit component, with multiple snap-fit components arranged at intervals along the circumference of the steel pipe pile body. The snap-fit component has a first slot for vertical insertion of the top of the sleeve and a second slot for vertical insertion of the top of the steel pipe pile body.
[0013] Furthermore, the top surface of the sleeve is higher than the top surface of the steel pipe pile body. The connecting positioning components include a first snap fastener connected to the top surface of the sleeve and an extended heightening cylinder that is sealed to the top surface of the steel pipe pile body. The lower end surface of the extended heightening cylinder is connected to the top surface of the steel pipe pile body through a second snap fastener. A force transmission plate is hinged on the first snap fastener, and the end of the force transmission plate away from the first snap fastener is horizontally overlapped on the top surface of the extended heightening cylinder. The first snap fastener has a first slot for vertical insertion of the top surface of the sleeve, and the second snap fastener has a second slot for vertical insertion of the top surface of the steel pipe pile body.
[0014] The beneficial effects of this invention are as follows: The steel pipe pile body and sleeve are coaxial, and the entire structure is driven into the soil to a set depth by static pressure or hammering, effectively ensuring that the steel pipe pile body is centered. This invention eliminates the pre-drilling process and eliminates the need for subsequent separate sand filling, making construction simpler. If hammering is used for pile formation, the coarse sand between the sleeve and the steel pipe pile body can be vibrated and compacted during the hammering process, ultimately improving the compactness of the coarse sand around the pile after pile formation. The coarse sand filling the space between the sleeve and the steel pipe pile body presses against the annular protrusion at the bottom of the steel pipe pile body, which can also improve the overall pull-out resistance of the steel pipe pile. The sleeve and other components in this invention can be recycled and reused, and only a few sets of sleeves are needed for a project, resulting in low implementation costs. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the overall structure during the implementation of the present invention.
[0016] Figure 2 for Figure 1 A partially enlarged structural diagram of the connection between the steel pipe pile body and the pile tip.
[0017] Figure 3 for Figure 1 A partially enlarged structural diagram of the pile top.
[0018] Figure 4 This is a partially enlarged structural diagram of the pile tip portion according to the second embodiment of the present invention.
[0019] Figure 5 This is a partially enlarged structural diagram of the pile top area according to the third embodiment of the present invention.
[0020] Figure 6 for Figure 5 The embodiment shown is a top view of the cap.
[0021] Figure 7 This is a partially enlarged structural diagram of the pile top area according to the fourth embodiment of the present invention.
[0022] The markings in the diagram are: 1. Steel pipe pile body, 2. Pile tip, 21. Annular boss, 22. Slot, 3. Sleeve, 4. Cap, 41. Annular boss of cap, 42. Cover plate, 51. First slot, 52. Second slot, 6. Heightening extension cylinder, 7. Force transmission plate, 8. Pile head, 9. Coarse sand. Detailed Implementation
[0023] The invention will now be further described with reference to the accompanying drawings.
[0024] like Figures 1 to 7 As shown, the steel pile structure used in this invention includes a vertically arranged steel pipe pile body 1. A coaxially arranged pile tip 2 is fixedly connected to the bottom end of the steel pipe pile body 1. The tip of the pile tip 2 faces downward, and the outer edge of the top surface of the pile tip 2 protrudes relative to the outer side wall of the bottom end of the steel pipe pile body 1 to form an annular boss 21. A sleeve 3 coaxially fitted around the outer periphery of the steel pipe pile body 1 is provided. A slot 22 is provided on the annular boss 21 for the bottom end of the sleeve 3 to be vertically inserted. After the bottom end of the sleeve 3 is inserted into the slot 22, the outer periphery of the steel pipe pile body 1, the inner periphery of the sleeve 3, and the surface of the annular boss 21 combine to form a coarse sand receiving cavity. The top end of the sleeve 3 is connected to the top end of the steel pipe pile body 1 through a connecting positioning member. The connecting positioning member enables the top end of the sleeve 3 and the top end of the steel pipe pile body 1 to have a first state of relative connection and fixation and a second state of relative separation. The connecting positioning member and the steel pipe pile body 1 are detachable. The top of sleeve 3 is in a first state of relative connection and fixation with the top of steel pipe pile 1, meaning that "during pile driving, the top of sleeve 3 and the top of steel pipe pile 1 can bear the force as a whole." The top of sleeve 3 is in a second state of relative separation from the top of steel pipe pile 1, meaning that "after pile driving is completed, sleeve 3 can be pulled upwards without being affected by steel pipe pile 1." The connecting positioning component and steel pipe pile 1 have a detachable connection structure, meaning that "after pile driving is completed, the connecting positioning component can be removed from steel pipe pile 1 without affecting subsequent construction." For ease of assembly and recycling, the connecting positioning component and sleeve 3 are usually also detachable. Sleeve 3 and connecting positioning component can be made of materials that meet strength requirements, typically steel.
[0025] During implementation, coarse sand 9 is pre-filled into the coarse sand receiving cavity formed by the combination of the outer peripheral wall of the steel pipe pile body 1, the inner peripheral wall of the sleeve 3, and the surface of the annular boss 21. The steel pipe pile body 1 and the sleeve 3 are driven into the soil to the set depth by static pressure or hammering. Then, the connecting positioning piece is removed, and the sleeve 3 is pulled out. During the pulling out of the sleeve 3, the coarse sand 9 can automatically fill the gap on the outer periphery of the steel pipe pile body 1 (the space formed after the sleeve 3 is pulled out). After the sleeve 3 is pulled out, coarse sand 9 is added to the top position to the design elevation according to the actual situation, and then hammered to compact it. Preferably, during the pulling out of the sleeve 3, the sleeve 3 is simultaneously tapped to help separate the coarse sand 9 from the sleeve 3.
[0026] The pile tip 2 can adopt various structural forms that facilitate soil breaking; the preferred scheme can be found in [reference needed]. Figure 2 The main body of pile tip 2 is a hollow cylindrical structure. The upper diameter of the central through hole of pile tip 2 is approximately equal to the inner diameter of the steel pipe pile body 1, and the lower sidewall of pile tip 2 tapers into a sharp point. This structure provides good strength for pile tip 2, and the extension direction of the sidewall of pile tip 2 is consistent with the direction of pile driving pressure, making it less prone to eccentric bending moments and resulting in better stress distribution. The hollow structure of pile tip 2 ensures that soil can enter the hollow section of steel pipe pile body 1 from the inside during soil displacement, enhancing the soil removal effect and avoiding excessive driving resistance. In an alternative design, the main body of pile tip 2 can be designed as a hollow conical cylindrical structure with an upper diameter larger than the lower diameter, as described in [reference needed]. Figure 4 To reduce the impact of frost heave, lubricant can be pre-applied to the surface of pile tip 2 before pile driving.
[0027] To ensure that the coarse sand receiving cavity has the largest possible coarse sand volume when pre-filled with coarse sand 9, the top surface of the sleeve 3 should not be lower than the top surface of the steel pipe pile body 1. To better protect the steel pipe pile body 1, it is even more preferable that the top surface of the sleeve 3 is higher than the top surface of the steel pipe pile body 1.
[0028] There are various ways to implement the connecting positioning element. The present invention provides some preferred embodiments as follows, for reference. Figure 5 The connecting positioning component can be a cap 4 of integral structure. The lower surface of the cap 4 has a first annular groove for vertical insertion of the top end of the sleeve 3 and a second annular groove for vertical insertion of the top end of the steel pipe pile 1. It should be noted that in some embodiments, the first annular groove can adopt a single-side wall structure, and the second annular groove can also adopt a single-side wall structure, for example... Figure 5 In the illustrated embodiment, the second annular groove omits the sidewall near the center of the steel pipe pile 1. The cap 4 also serves to protect the steel pipe pile 1.
[0029] To further increase the pre-load capacity of coarse sand 9, please refer to Figure 5 and Figure 6In this invention, the top surface of the sleeve 3 is not lower than the top surface of the steel pipe pile body 1. The lower surface of the cap 4 has a cap annular boss 41 extending into the coarse sand receiving cavity. The main body of the cap 4 has a cap cavity with a top opening. The cap cavity has several sand-flowing holes connected to the coarse sand receiving cavity in the area of the lower surface of the cap annular boss 41. The sand-flowing holes are usually evenly spaced along the circumferential direction. The top opening of the cap cavity is equipped with an openable and closable cover plate 42. The cover plate 42 can usually adopt a hinged rotating opening and closing method. Of course, in some embodiments, a reusable opening and closing method can also be used instead. In practice, during construction, after the top of the sleeve 3 is connected and fixed to the top of the steel pipe pile body 1 using the cap 4, coarse sand 9 is also pre-filled in the cap cavity before pile driving. The preferred method for pile formation is hammer driving. During the hammering process, the coarse sand 9 between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile 1 is vibrated and compacted. This causes the top height of the coarse sand 9 between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile 1 to decrease, and the coarse sand 9 in the cap cavity will fall through the sand flow hole to replenish the area between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile 1. This implementation method also ultimately improves the compactness of the coarse sand around the pile after pile formation.
[0030] See Figure 7 In other embodiments, the connecting positioning element can be a snap-fit element, with multiple snap-fit elements arranged at intervals along the circumference of the steel pipe pile body 1. Each snap-fit element has a first slot 51 for vertical insertion of the top end of the sleeve 3 and a second slot 52 for vertical insertion of the top end of the steel pipe pile body 1. In practice, the snap-fit element can be directly engaged with both the sleeve 3's top wall and the steel pipe pile body 1's top wall simultaneously, making assembly and disassembly relatively convenient.
[0031] To increase the pre-loading capacity of pre-loaded coarse sand 9, refer to Figure 3 In some other embodiments, the top surface of the sleeve 3 can be designed to be higher than the top surface of the steel pipe pile 1. The connecting positioning component includes a first snap fastener connected to the top surface of the sleeve 3 and an extension tube 6 that is sealed to the top surface of the steel pipe pile 1. The lower end surface of the extension tube 6 is connected to the top surface of the steel pipe pile 1 through a second snap fastener. A force transmission plate 7 is hinged on the first snap fastener. The end of the force transmission plate 7 away from the first snap fastener is horizontally overlapped on the top surface of the extension tube 6. The first snap fastener has a first slot 51 for vertical insertion of the top surface of the sleeve 3, and the second snap fastener has a second slot 52 for vertical insertion of the top surface of the steel pipe pile 1.
Claims
1. A steel pile construction method applicable to permafrost regions, wherein the steel pile structure comprises a vertically arranged steel pipe pile body (1), and a coaxially arranged pile tip (2) is fixedly connected to the bottom end of the steel pipe pile body (1), with the tip of the pile tip (2) pointing downwards, characterized in that: The main body of the pile tip (2) is a hollow cylindrical structure. The upper diameter of the central through hole of the pile tip (2) is equivalent to the inner diameter of the steel pipe pile body (1). The lower side wall of the pile tip (2) is tapered into a sharp shape. The outer edge of the top surface of the pile tip (2) protrudes relative to the outer side wall of the bottom end of the steel pipe pile body (1) to form an annular boss (21). A sleeve (3) coaxial with it is fitted around the outer periphery of the steel pipe pile body (1). A slot (22) for vertical insertion of the bottom end of the sleeve (3) is provided on the annular boss (21). After the bottom end of the sleeve (3) is inserted into the slot (22), the outer periphery of the steel pipe pile body (1), the inner periphery of the sleeve (3), and the surface of the annular boss (21) combine to form a coarse sand receiving cavity. The top end of the sleeve (3) is connected to the top end of the steel pipe pile body (1) through a connecting positioning component. The connecting positioning component makes the top end of the sleeve (3) and the top end of the steel pipe pile body (1) connected by a connecting positioning component. The ends have a first state of relative connection and a second state of relative separation; the connection positioning component and the steel pipe pile body (1) are detachable connection structures; the construction includes the following steps: coarse sand (9) is pre-filled in the coarse sand receiving cavity formed by the combination of the outer peripheral wall of the steel pipe pile body (1), the inner peripheral wall of the sleeve (3) and the surface of the annular boss (21), and the top of the sleeve (3) is connected and fixed to the top of the steel pipe pile body (1) using the connection positioning component. The steel pipe pile body (1) and the sleeve (3) are squeezed into the soil to the set depth by static pressure or hammering. Then the connection positioning component is removed and the sleeve (3) is pulled out. During the process of pulling out the sleeve (3), the coarse sand (9) automatically fills the gaps on the outer periphery of the steel pipe pile body (1). After the sleeve (3) is pulled out, coarse sand (9) is added to the top position to the design elevation according to the actual situation and hammered to compact.
2. The steel pile construction method applicable to permafrost regions as described in claim 1, characterized in that: Before driving the pile, the surface of the pile tip (2) is pre-coated with lubricant; during the process of pulling out the sleeve (3), the sleeve (3) is simultaneously struck to help the coarse sand (9) separate from the sleeve (3).
3. The steel pile construction method applicable to permafrost regions as described in claim 1, characterized in that: The top surface of the sleeve (3) is not lower than the top surface of the steel pipe pile body (1).
4. The steel pile construction method applicable to permafrost regions as described in any one of claims 1 to 3, characterized in that: The connecting positioning component is a cap (4). The lower surface of the cap (4) has a first annular groove for vertical insertion of the top of the sleeve (3) and a second annular groove for vertical insertion of the top of the steel pipe pile (1).
5. The steel pile construction method applicable to permafrost regions as described in claim 4, characterized in that: The lower surface of the cap (4) has a cap annular boss (41) that extends into the coarse sand receiving cavity. The main body of the cap (4) has a cap cavity with an open top. The cap cavity has several sand-flowing holes that connect to the coarse sand receiving cavity in the area where the lower surface of the cap annular boss (41) is located. The top opening of the cap cavity is equipped with an openable and closable cover plate (42). During construction, after the cap (4) is used to connect and fix the top of the sleeve (3) to the top of the steel pipe pile (1), coarse sand (9) is also pre-filled in the cap cavity before pile driving.
6. The steel pile construction method applicable to permafrost regions as described in any one of claims 1 to 3, characterized in that: The connecting positioning component is a snap fastener. Multiple snap fasteners are arranged at intervals along the circumference of the steel pipe pile body (1). The snap fastener has a first slot (51) for vertical insertion of the top of the sleeve (3) and a second slot (52) for vertical insertion of the top of the steel pipe pile body (1).
7. The steel pile construction method applicable to permafrost regions as described in any one of claims 1 to 3, characterized in that: The top surface of the sleeve (3) is higher than the top surface of the steel pipe pile body (1). The connecting positioning component includes a first buckle connected to the top of the sleeve (3) and an extension tube (6) that is sealed to the top of the steel pipe pile body (1). The lower end of the extension tube (6) is connected to the top of the steel pipe pile body (1) through a second buckle. A force transmission plate (7) is hinged on the first buckle. The end of the force transmission plate (7) away from the first buckle is horizontally overlapped on the top of the extension tube (6). The first buckle has a first slot (51) for vertical insertion of the top of the sleeve (3), and the second buckle has a second slot (52) for vertical insertion of the top of the steel pipe pile body (1).