Construction methods for engineering piles in permafrost regions

Abstract

This invention relates to a construction method for engineering piles suitable for permafrost regions, belonging to the field of pile foundation engineering technology. The steel pile structure used in this invention includes a vertically arranged steel pipe pile body. A coaxially arranged annular support plate is fixedly connected to the outer wall of the bottom end of the steel pipe pile body. A sleeve coaxial with the steel pipe pile body is fitted around its outer periphery. The lower end sidewall of the sleeve tapers into a sharp point to form a pile tip. Multiple sleeve pin connection grooves are provided on the lower inner sidewall of the sleeve above the pile tip. Each sleeve pin connection groove is equipped with a corresponding pin. When the steel pipe pile body and the sleeve are fixed together by the pins, the outer wall of the steel pipe pile body, the annular support plate, and the inner wall of the sleeve form a pre-filled material receiving cavity. An automatic separation structure is provided between the steel pipe pile body and the sleeve. During construction, coarse sand is pre-filled into the pre-filled material receiving cavity. The steel pipe pile body and the sleeve are driven into the soil to a set depth using static pressure or hammering. Finally, the sleeve is pulled out.

Description

TECHNICAL FIELD

[0001] The application relates to a construction method of an engineering pile suitable for a frozen soil area and belongs to the technical field of pile foundation engineering. BACKGROUND

[0002] High-altitude mountain sites are flat and open, have less shelter and sufficient sunlight, and are relatively suitable for construction of photovoltaic projects. However, the high-altitude mountain climate is cold and rainfall is large, some sites are located in gentle slope sections, the underground water level is relatively high, and the frost heaving force is relatively obvious. The damage forms of the frozen soil disasters in the site mainly include frost heaving hills, thawing pits, freezing and thawing grass hills and frozen soil cracks.

[0003] During the freezing and thawing process of the frozen soil foundation, frost heaving and thawing often occur, and excessive frost-thawing deformation can cause serious damage to buildings. When the foundation burial depth exceeds the freezing depth, the tangential frost heaving force acts on the side surface of the foundation; when the foundation burial depth is shallower than the freezing depth, the normal frost heaving force also acts on the bottom surface of the foundation. For the soil foundation, the traditional method needs to preform a hole with a larger diameter than the diameter of the steel pile, then the steel pile is placed in the hole, and then coarse sand is penetrated around the steel pile. The high water permeability of the filled coarse sand is used to reduce the influence of pore water and underground water and reduce the influence of the tangential frost heaving force. Such a construction method has two problems: 1. Since the preformed hole has a larger diameter, the combination of the coarse sand around the pile is not so tight; 2. After the preformed hole, it is difficult to ensure that the steel pile is in the middle. SUMMARY

[0004] The technical problem to be solved by the application is to provide a construction method of an engineering pile suitable for a frozen soil area, which can effectively ensure the positioning accuracy of the pile body, is more convenient to construct, and the coarse sand around the pile can be combined more tightly.

[0005] The technical scheme adopted by the present application to solve the above technical problems is: the engineering pile construction method suitable for permafrost regions, the steel pile structure adopted includes a vertically arranged steel pipe pile body, the outer side wall of the bottom end of the steel pipe pile body is fixedly connected with a coaxially arranged annular support plate, the annular support plate extends downwardly relative to the axis of the steel pipe pile body, the outer periphery of the steel pipe pile body is sleeved with a sleeve coaxial with the steel pipe pile body, the annular support plate and the inner wall of the sleeve form a sliding fit, the lower end side wall of the sleeve is contracted into a sharp shape to form a pile tip part, the lower end inner side wall of the sleeve is provided with a sleeve bolt connecting groove above the pile tip part, a plurality of sleeve bolt connecting grooves are arranged at intervals along the circumference of the sleeve, each sleeve bolt connecting groove includes a vertical groove part on the inner side wall of the sleeve and an inclined hole part connected to the lower end of the vertical groove part, the axis of the inclined hole part extends downwardly relative to the vertical groove part, the end of the inclined hole part away from the vertical groove part is a closed structure, each sleeve bolt connecting groove is correspondingly provided with a bolt, the bolt is composed of a bolt vertical section matched with the vertical groove part and a bolt inclined section matched with the inclined hole part, the lower surface of the annular support plate has a vertical insertion groove matched with the bolt vertical section; when the steel pipe pile body and the sleeve are connected and fixed by the bolt, the upper end of the bolt vertical section is located in the vertical insertion groove, the lower end of the bolt inclined section is located in the inclined hole part, at this time, the outer wall of the steel pipe pile body, the annular support plate and the inner wall of the sleeve form a pre-filled material containing cavity; when the steel pipe pile body moves upward relative to the sleeve along the axial direction, the bolt can be separated from the vertical insertion groove and fall back into the sleeve bolt connecting groove by its own gravity at this time, the bolt vertical section is completely located in the vertical groove part; the top end of the sleeve and the top end of the steel pipe pile body are connected by a connecting positioning member, the connecting positioning member makes the top end of the sleeve and the top end of the steel pipe pile body 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 are a detachable connection structure; the construction includes the following steps: first, the steel pipe pile body and the sleeve are connected and fixed by the bolt, the pre-filled material containing cavity is pre-filled with coarse sand, then the top end is connected and fixed by the connecting positioning member, the steel pipe pile body and the sleeve are extruded into the soil to a set depth in the form of static pressure or hammering, then the connecting positioning member at the top end of the steel pipe pile body is removed, the steel pipe pile body is lifted a set distance along the axial direction, the bolt is separated from the vertical insertion groove and falls back into the sleeve bolt connecting groove by its own gravity, then the steel pipe pile body is lowered to the bottom end again, and finally the sleeve is pulled out, in the process of pulling out the sleeve, the coarse sand fills the gap around the steel pipe pile body, after the sleeve is pulled out, coarse sand is supplemented to the design elevation at the top end position according to the actual situation, and the coarse sand is compacted by hammering.

[0006] Further, before the pre-filled material containing cavity is filled with coarse sand, gravel is pre-installed; the pre-filled material containing cavity is sequentially formed with a gravel layer and a coarse sand layer from bottom to top.

[0007] Further, before assembly, the surface of the bolt is pre-coated with a lubricant; before piling, the surface of the pile tip part is pre-coated with a lubricant.

[0008] Further, in the process of pulling out the sleeve, the sleeve is hit to assist the coarse sand to separate from the sleeve.

[0009] Further, the top end surface of the sleeve is not lower than the top end surface of the steel pipe pile body.

[0010] Further, the connecting positioning member is a cap, and the lower surface of the cap is provided with a first annular clamping groove for vertically inserting the top end of the sleeve and a second annular clamping groove for vertically inserting the top end of the steel pipe pile body.

[0011] Further, the lower surface of the cap is provided with a cap annular boss extending into the pre-filled material accommodating cavity, and the main body of the cap is provided with a cap cavity with an open top, and the cap cavity is provided with a plurality of sand flow holes communicating with the pre-filled material accommodating cavity in the area where the lower surface of the cap annular boss is located; and the open top of the cap cavity is provided with an openable and closable cover plate. In construction, after the top end of the sleeve is connected and fixed with the top end of the steel pipe pile body by the cap, coarse sand is also preloaded in the cap cavity before piling.

[0012] Further, the connecting positioning member is a buckle member, and a plurality of buckle members are arranged along the circumference of the steel pipe pile body, and the buckle member is provided with a first clamping groove for vertically inserting the top end of the sleeve and a second clamping groove for vertically inserting the top end of the steel pipe pile body.

[0013] Further, the top end surface of the sleeve is higher than the top end surface of the steel pipe pile body, the connecting positioning member comprises a first buckle member connected with the top end of the sleeve and a heightened extension cylinder connected with the top end of the steel pipe pile body in a sealed manner, the lower end surface of the heightened extension cylinder is connected with the top end of the steel pipe pile body through a second buckle member; a force transmission plate is hinged to the first buckle member, and the end of the force transmission plate away from the first buckle member is horizontally overlapped on the top end of the heightened extension cylinder; the first buckle member is provided with a first clamping groove for vertically inserting the top end of the sleeve, and the second buckle member is provided with a second clamping groove for vertically inserting the top end of the steel pipe pile body.

[0014] The steel pipe pile body and the sleeve of the present application are coaxial, and the whole is extruded into the soil to the set depth in the form of static pressure or hammering, which can effectively ensure that the steel pipe pile body is centrally arranged. The present application eliminates the process of pre-pore, and does not need to separately fill sand in the later stage, and the construction is relatively simple; if the pile is formed in the form of hammering, the coarse sand between the sleeve and the steel pipe pile body can also be vibrated and compacted during the hammering process, which finally improves the compactness of the coarse sand around the formed pile. The coarse sand filled between the sleeve and the steel pipe pile body also improves the pull-out resistance of the whole steel pipe pile, as the coarse sand presses on the annular support plate at the bottom of the steel pipe pile body. The sleeve and other components in the present application can be recycled and used, and only a few sets of sleeves are needed for a project, which has a low implementation cost. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the overall structure schematic diagram when the present application is implemented.

[0016] Figure 2 For Figure 1 Partial enlarged structural diagram of the connection between the bottom end of the steel pipe pile body and the bottom end of the sleeve in the right lower side area.

[0017] Figure 3 For Figure 1 Partial enlarged structural diagram of the pile top part in the right lower side area.

[0018] Figure 4 For Figure 1 Cap top view adopted by the embodiment shown in the right lower side area.

[0019] Figure 5 Partial enlarged structural diagram of the pile top part of the second embodiment of the present application.

[0020] Figure 6 Partial enlarged structural diagram of the pile top part of the third embodiment of the present application.

[0021] Marked in the figure: steel pipe pile body 1, annular support plate 11, vertical insertion slot 12, insertion pin 2, sleeve 3, pile tip part 31, sleeve insertion pin connection slot 32, vertical slot part 33, inclined hole part 34, cap 4, cap annular boss 41, cover plate 42, first clamping slot 51, second clamping slot 52, heightened extension cylinder 6, force transmission plate 7, coarse sand 9. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with the drawings.

[0023] As Figures 1 to 6As shown, the steel pile structure adopted by the present application comprises a vertically arranged steel pipe pile body 1, the outer side wall of the bottom end of the steel pipe pile body 1 is fixedly connected with a coaxially arranged annular support plate 11, the annular support plate 11 extends obliquely downward relative to the axis of the steel pipe pile body 1 (the oblique downward extension here should be understood in a broad sense, the radial section of the annular support plate 11 can be an inclined plate structure or an arc-shaped plate structure), the outer periphery of the steel pipe pile body 1 is sleeved with a sleeve 3 coaxial therewith, the annular support plate 11 and the inner wall of the sleeve 3 form a sliding fit, the lower end side wall of the sleeve 3 is contracted into a sharp shape to form a pile tip part 31, the lower end inner side wall of the sleeve 3 is provided with a sleeve bolt connecting groove 32 at a position above the pile tip part 31, a plurality of sleeve bolt connecting grooves 32 are arranged along the circumference of the sleeve 3, each sleeve bolt connecting groove 32 comprises a vertical groove part 33 located at the inner side wall of the sleeve 3 and an inclined hole part 34 connected to the lower end of the vertical groove part 33, the axis of the inclined hole part 34 extends obliquely downward relative to the vertical groove part 33, and the end of the inclined hole part 34 away from the vertical groove part 33 is of a closed structure, each sleeve bolt connecting groove 32 is correspondingly provided with a bolt 2, the bolt 2 is composed of a bolt vertical section matched with the vertical groove part 33 and a bolt oblique section matched with the inclined hole part 34, and the lower surface of the annular support plate 11 has a vertical insertion groove 12 matched with the bolt vertical section; when the steel pipe pile body 1 and the sleeve 3 are connected and fixed by the bolt 2, the upper end of the bolt vertical section is located in the vertical insertion groove 12 and the lower end of the bolt oblique section is located in the inclined hole part 34, at this time, the outer wall of the steel pipe pile body 1, the annular support plate 11 and the inner wall of the sleeve 3 form a pre-filled material containing cavity; when the steel pipe pile body 1 moves upward relative to the sleeve 3 along the axial direction, the bolt 2 can rely on its own gravity to separate from the vertical insertion groove 12 and fall back into the sleeve bolt connecting groove 32, at this time, the bolt vertical section is completely located in the vertical groove part 33 (that is, the whole bolt 2 is completely hidden in the sleeve bolt connecting groove 32, the bolt 2 does not have a protruding part relative to the inner wall of the sleeve 3, at this time, the sleeve 3 can be pulled out upward); the top end of the sleeve 3 and the top end of the steel pipe pile body 1 are connected by a connecting positioning member, the connecting positioning member makes the top end of the sleeve 3 and the top end of the steel pipe pile body 1 have a first state of relative connection fixation and a second state of relative separation; the connecting positioning member and the steel pipe pile body 1 are in a detachable connection structure. The first state of relative connection fixation of the top end of the sleeve 3 and the top end of the steel pipe pile body 1 means that "when the pile is pressed, the top end of the sleeve 3 and the top end of the steel pipe pile body 1 can be integrally stressed", and the second state of relative separation of the top end of the sleeve 3 and the top end of the steel pipe pile body 1 means that "after the pile pressing is completed, the sleeve 3 can be pulled out upward and will not be affected by the steel pipe pile body 1". The detachable connection structure between the connecting positioning member and the steel pipe pile body 1 means that "after the pile pressing is completed, the connecting positioning member can be removed from the steel pipe pile body 1 and will not affect the subsequent construction". In order to facilitate assembly and recycling, the connecting positioning member and the sleeve 3 are usually also in a detachable connection structure.The annular support plate 11, the plug 2, the sleeve 3 and the connecting positioning member can be made of a material meeting the strength requirement, and are usually made of steel.

[0024] In the implementation, the steel pipe pile body 1 is first connected and fixed with the sleeve 3 through the plug 2, and the plug 2 cannot naturally fall due to the limiting action of the vertical insertion groove 12. At this time, the outer wall of the steel pipe pile body 1, the annular support plate 11 and the inner wall of the sleeve 3 form a pre-filled material containing cavity. The pre-filled material containing cavity is pre-filled with coarse sand 9 (preferably, the coarse sand 9 is pre-filled after the gravel is pre-filled), and then is connected and fixed at the top end through the connecting positioning member. The steel pipe pile body 1 and the sleeve 3 are integrally extruded into the soil to a set depth in a static pressure or hammering form. Then, the connecting positioning member at the top end of the steel pipe pile body 1 is removed, the steel pipe pile body 1 is lifted along the axial direction by a set distance (determined according to the vertical depth of the vertical insertion groove 12), the plug 2 is separated from the vertical insertion groove 12 and falls back into the sleeve plug connection groove 32 due to its own gravity, and then the steel pipe pile body 1 is lowered to the bottom end. Finally, the sleeve 3 is pulled out. In the process of pulling out the sleeve 3, the coarse sand 9 can automatically fill the gap around the steel pipe pile body 1 (the space formed after the sleeve 3 is pulled out). After the sleeve 3 is pulled out, the coarse sand 9 is supplemented to the design elevation at the top end according to the actual situation, and is compacted by hammering. In the process of pulling out the sleeve 3, the sleeve 3 can be knocked to assist the separation of the coarse sand 9 and the sleeve 3. The purpose of pre-filling the coarse sand 9 after pre-filling the gravel is to prevent the coarse sand 9 from falling into the sleeve plug connection groove 32 from the gap at the outer edge of the annular support plate 11, so as to avoid affecting the automatic falling of the plug 2. It can be understood that when the gap between the outer edge of the annular support plate 11 and the inner wall of the sleeve 3 is small enough or the two are in contact (the coarse sand 9 cannot naturally enter), the coarse sand 9 can also be directly filled. In order to facilitate the automatic falling of the plug 2, the outer surface of the plug 2 can be pre-coated with a lubricant.

[0025] In order to reduce the influence of frost heaving force, the surface of the pile tip 31 can be pre-coated with a lubricant before piling.

[0026] In order to make the pre-filled material containing cavity have the largest coarse sand volume when the coarse sand 9 is pre-filled, the top end surface of the sleeve 3 is not lower than the top end surface of the steel pipe pile body 1. In order to better protect the steel pipe pile body 1, the top end surface of the sleeve 3 can be further preferably higher than the top end surface of the steel pipe pile body 1.

[0027] The connecting positioning member can have various implementation manners, and the present application provides some preferred embodiments as follows, which can be referred to in Figure 3 The connecting positioning member can be a cap 4 in an integral structure. The lower surface of the cap 4 has a first annular clamping groove for vertically inserting the top end of the sleeve 3 and a second annular clamping groove for vertically inserting the top end of the steel pipe pile body 1. It should be noted that in some embodiments, the first annular clamping groove can adopt a single side wall structure, and the second annular clamping groove can also adopt a single side wall structure, for example Figure 3In the shown embodiment, the second annular clamping groove is devoid of the side wall close to the center of the steel pipe pile body 1. The cap 4 can also serve to protect the steel pipe pile body 1.

[0028] To further increase the preloading capacity of the coarse sand 9, refer to Figure 3 and Figure 4 In the present application, the top end surface of the sleeve 3 is not lower than the top end surface of the steel pipe pile body 1, the lower surface of the cap 4 has a cap annular boss 41 extending into the prefill material accommodating cavity, the main body of the cap 4 has a cap cavity with a top opening, the cap cavity is provided with a plurality of sand flow holes communicating with the prefill material accommodating cavity at the area where the lower surface of the cap annular boss 41 is located, and the sand flow holes are usually uniformly and circumferentially spaced; the top opening of the cap cavity is provided with an openable and closable cover plate 42; the cover plate 42 usually adopts a hinge structure for rotation type opening and closing, and of course in some embodiments, a repeatable disassembly and assembly type opening and closing can also be used instead. In implementation, the cap cavity can also be preloaded with coarse sand 9, and this structure is preferably used for hammering pile forming, in the process of hammering, the coarse sand 9 between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile body 1 can be vibrated and compacted, 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 body 1 will be lowered, and the coarse sand 9 in the cap cavity will fall through the sand flow holes to supplement the coarse sand 9 between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile body 1. This embodiment can also finally improve the compactness of the coarse sand around the pile after pile forming.

[0029] Refer to Figure 5 In some other embodiments, the connecting and positioning member can be a buckle member, a plurality of buckle members are arranged along the circumference of the steel pipe pile body 1, the buckle member has a first clamping groove 51 for vertical insertion of the top end of the sleeve 3 and a second clamping groove 52 for vertical insertion of the top end of the steel pipe pile body 1. In implementation, the buckle member can be directly clamped with the sleeve 3 and the steel pipe pile body 1, and disassembly and assembly are relatively convenient.

[0030] To increase the preloading capacity of the preloaded coarse sand 9, refer to Figure 6 In some other embodiments, the top end surface of the sleeve 3 can be designed to be higher than the top end surface of the steel pipe pile body 1, the connecting and positioning member includes a first buckle member connected with the top end of the sleeve 3 and a heightened extension cylinder 6 connected with the top end of the steel pipe pile body 1 in airtight manner, the lower end surface of the heightened extension cylinder 6 is connected with the top end of the steel pipe pile body 1 through a second buckle member; a force transmission plate 7 is hinged to the first buckle member, and the end of the force transmission plate 7 away from the first buckle member is horizontally overlapped on the top end of the heightened extension cylinder 6; the first buckle member has a first clamping groove 51 for vertical insertion of the top end of the sleeve 3, and the second buckle member has a second clamping groove 52 for vertical insertion of the top end of the steel pipe pile body 1.

Claims

1. A method for construction of engineering piles suitable for permafrost regions, the steel pile structure used comprises a vertically arranged steel pipe pile body (1), characterized in that: The bottom end outer wall of the steel pipe pile body (1) is fixedly connected with a coaxially arranged annular support plate (11), the annular support plate (11) extends obliquely downward relative to the axis of the steel pipe pile body (1), the outer periphery of the steel pipe pile body (1) is sleeved with a sleeve (3) coaxial therewith, the annular support plate (11) and the inner wall of the sleeve (3) form a sliding fit, the lower end side wall of the sleeve (3) is contracted into a sharp shape to form a pile tip portion (31), the lower end inner side wall of the sleeve (3) is provided with a sleeve bolt connecting groove (32) at a position above the pile tip portion (31), a plurality of sleeve bolt connecting grooves (32) are arranged at intervals along the circumference of the sleeve (3), each sleeve bolt connecting groove (32) comprises a vertical groove portion (33) located on the inner side wall of the sleeve (3) and an inclined hole portion (34) connected to the lower end of the vertical groove portion (33), the axis of the inclined hole portion (34) extends obliquely downward relative to the vertical groove portion (33), and the end of the inclined hole portion (34) away from the vertical groove portion (33) is a closed structure, each sleeve bolt connecting groove (32) is correspondingly provided with a bolt (2), the bolt (2) is composed of a bolt vertical section matched with the vertical groove portion (33) and a bolt inclined section matched with the inclined hole portion (34), and the lower surface of the annular support plate (11) has a vertical insertion groove (12) matched with the bolt vertical section; when the steel pipe pile body (1) and the sleeve (3) are connected and fixed by the bolt (2), the upper end of the bolt vertical section is located in the vertical insertion groove (12), the lower end of the bolt inclined section is located in the inclined hole portion (34), and at this time, the outer wall of the steel pipe pile body (1), the annular support plate (11) and the inner wall of the sleeve (3) form a pre-filled material containing cavity; when the steel pipe pile body (1) moves upward relative to the sleeve (3) along the axial direction, the bolt (2) can be separated from the vertical insertion groove (12) and fall into the sleeve bolt connecting groove (32) by its own gravity, at this time, the bolt vertical section is completely located in the vertical groove portion (33); the top end of the sleeve (3) and the top end of the steel pipe pile body (1) are connected by a connecting positioning piece, the connecting positioning piece makes the top end of the sleeve (3) and the top end of the steel pipe pile body (1) have a first state of relative connection and fixation and a second state of relative separation; the connecting positioning piece and the steel pipe pile body (1) are detachably connected.The construction includes the following steps: firstly, the steel pipe pile body (1) is connected and fixed with the sleeve (3) through the bolt (2), the coarse sand (9) is pre-filled in the pre-filling material containing cavity, then the connecting and positioning member is connected and fixed at the top end, the steel pipe pile body (1) and the sleeve (3) are integrally extruded into the soil to the set depth in the form of static pressure or hammering, then the connecting and positioning member at the top end of the steel pipe pile body (1) is removed, the steel pipe pile body (1) is lifted along the axial direction by a set distance, the bolt (2) is separated from the vertical insertion slot (12) and falls into the sleeve bolt insertion slot (32) by its own gravity, then the steel pipe pile body (1) is lowered to the bottom end again, finally the sleeve (3) is pulled out, in the process of pulling out the sleeve (3), the coarse sand (9) fills the gap around the steel pipe pile body (1), after the sleeve (3) is pulled out, the coarse sand (9) is supplemented to the design elevation at the top end position according to the actual situation, and is compacted by hammering.

2. The method for construction of engineering piles suitable for use in frozen ground regions as claimed in claim 1, wherein: The pre-filling material accommodating cavity is filled with coarse sand (9) and gravel in advance.

3. The method for construction of engineering piles suitable for use in frozen ground regions as claimed in claim 1, wherein: The surface of the pin (2) is coated with lubricant before assembly.

4. The method for construction of engineering piles suitable for use in frozen ground regions as claimed in claim 1, wherein: The sleeve (3) is knocked during pulling out to separate the coarse sand (9) from the sleeve (3).

5. The method for construction of engineering piles suitable for use in frozen ground regions as claimed in claim 1, wherein: The top end surface of the sleeve (3) is not lower than the top end surface of the steel pipe pile body (1).

6. The method for construction of engineering piles suitable for use in frozen ground regions according to any one of claims 1 to 5, characterized in that: The connecting positioning member is a cap (4), the lower surface of the cap (4) is provided with a first annular clamping groove for vertically inserting the top end of the sleeve (3) and a second annular clamping groove for vertically inserting the top end of the steel pipe pile body (1).

7. The method for construction of engineering piles suitable for use in frozen ground regions as claimed in claim 6, wherein: The lower surface of the cap (4) is provided with a cap annular boss (41) extending into the pre-filling material accommodating cavity, the main body of the cap (4) is provided with a cap cavity with an open top, the cap cavity is provided with a plurality of sand flow holes communicating with the pre-filling material accommodating cavity in the area where the lower surface of the cap annular boss (41) is located; the open top of the cap cavity is provided with an openable and closable cover plate (42); during construction, the top end of the sleeve (3) and the top end of the steel pipe pile body (1) are connected and fixed by the cap (4), and coarse sand (9) is also pre-filled in the cap cavity before piling.

8. The method for construction of engineering piles suitable for use in frozen ground regions according to any one of claims 1 to 5, characterized in that: The connecting positioning member is a buckle member, a plurality of buckle members are arranged along the circumference of the steel pipe pile body (1), the buckle member is provided with a first clamping groove (51) for vertically inserting the top end of the sleeve (3) and a second clamping groove (52) for vertically inserting the top end of the steel pipe pile body (1).

9. The method for construction of engineering piles in permafrost regions as claimed in any one of claims 1 to 5, wherein: The top end surface of the sleeve (3) is higher than the top end surface of the steel pipe pile body (1), the connecting positioning member includes a first buckle member connected with the top end of the sleeve (3) and a height-extended cylinder (6) in airtight connection with the top end of the steel pipe pile body (1), the lower end surface of the height-extended cylinder (6) is connected with the top end of the steel pipe pile body (1) through a second buckle member; a force transmission plate (7) is hinged to the first buckle member, the end of the force transmission plate (7) away from the first buckle member is horizontally overlapped on the top end of the height-extended cylinder (6); the first buckle member is provided with a first clamping groove (51) for vertically inserting the top end of the sleeve (3), and the second buckle member is provided with a second clamping groove (52) for vertically inserting the top end of the steel pipe pile body (1).

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