CN116716880A - Engineering pile construction method suitable for frozen soil area - Google Patents

Abstract

The invention relates to an engineering pile construction method suitable for a frozen soil area, and belongs to the technical field of pile foundation engineering. The steel pile structure comprises a steel pipe pile body which is vertically arranged, an annular supporting plate which is coaxially arranged is fixedly connected to the outer side wall of the bottom end of the steel pipe pile body, a sleeve which is coaxial with the steel pipe pile body is sleeved on the outer periphery of the steel pipe pile body, the lower side wall of the sleeve is contracted into a sharp shape to form a pile tip, a plurality of sleeve bolt connecting grooves are formed in the upper position of the pile tip on the lower side wall of the sleeve, each sleeve bolt connecting groove is correspondingly provided with a bolt, and when the steel pipe pile body is fixedly connected with the sleeve through the bolts, the outer wall of the steel pipe pile body, the annular supporting plate and the inner wall of the sleeve form a prefilled material accommodating cavity; an automatic separation structure is arranged between the steel pipe pile body and the sleeve; during construction, coarse sand is filled in the prefilled material accommodating cavity in advance, the whole steel pipe pile body and the sleeve are extruded into soil to a set depth in a static pressure or hammering mode, and finally the sleeve is pulled out.

Description

Engineering pile construction method suitable for frozen soil area

Technical Field

The invention relates to an engineering pile construction method suitable for a frozen soil area, and belongs to the technical field of pile foundation engineering.

Background

The high-altitude mountain site is flat and open, has less shielding and sufficient sunlight, and is more suitable for construction of photovoltaic projects. However, the high-altitude mountain land is cold in climate and large in rainfall capacity, part of the land is located in a gentle slope foot section, the underground water level is high, the frost heaving acting force is obvious, and the damage modes of the frost soil disasters in the land mainly comprise a frost heaving hills, a thawing pit, a frost thawing grass hills, frost soil cracks and the like.

In the freezing and thawing process of the frozen soil foundation, frost heaving and thawing sinking are often generated, and excessive freezing and thawing deformation can cause serious damage to the building. When the embedding depth of the foundation exceeds the freezing depth, the tangential frost heaving force acts on the side surface of the foundation; when the embedding depth of the foundation is shallower than the freezing depth, normal frost heaving is also acted on the bottom surface of the foundation. Aiming at the soil foundation, the construction of the traditional method needs to form a hole with a diameter larger than that of the steel pile in advance, coarse sand is injected into the periphery of the steel pile after the steel pile is placed, and the influence of pore water and underground water and the influence of tangential frost heaving force are reduced by utilizing the high water permeability of the filled coarse sand. There are two problems with such a construction method: 1. because a hole with larger diameter is preformed, the pile periphery penetration coarse sand is not tightly combined; 2. and the steel pile is put in after the pre-pore is formed, so that the steel pile is difficult to ensure to be in the middle.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: the engineering pile construction method suitable for the frozen soil area can effectively ensure the positioning precision of the pile body, is simpler and more convenient to construct, and coarse sand around the pile can be combined more tightly.

The technical scheme adopted by the invention for solving the technical problems is as follows: the construction method of the engineering pile suitable for the frozen soil area comprises the steps that the adopted steel pile structure comprises a steel pipe pile body which is vertically arranged, an annular supporting plate which is coaxially arranged is fixedly connected to the outer side wall of the bottom end of the steel pipe pile body, the annular supporting plate extends obliquely downwards relative to the axis of the steel pipe pile body, a sleeve which is coaxial with the annular supporting plate is sleeved on the outer periphery of the steel pipe pile body, the annular supporting plate and the inner wall of the sleeve form sliding fit, the side wall of the lower end of the sleeve contracts into a sharp shape to form a pile tip, sleeve bolt connecting grooves are arranged at the upper position of the pile tip on the inner side wall of the lower end of the sleeve at intervals along the circumferential direction of the sleeve, each sleeve bolt connecting groove comprises a vertical groove part which is positioned on the inner side wall of the sleeve and an inclined hole part which is connected to the lower end of the vertical groove part, the axis of the inclined hole part extends obliquely downwards relative to the vertical groove part, one end of the inclined hole part far away from the vertical groove part is of the sealing structure, each sleeve bolt connecting groove is correspondingly provided with a bolt, and the bolt is formed by a bolt vertical section which is matched with the vertical section of the bolt, and an inclined section matched with the bolt; when the steel pipe pile body is fixedly connected with the sleeve through the bolt, the upper end of the vertical section of the bolt is positioned in the vertical slot, the lower end of the inclined section of the bolt is positioned in the inclined hole part, and the outer wall of the steel pipe pile body, the annular supporting plate and the inner wall of the sleeve form a prefilled material accommodating cavity; when the steel pipe pile body moves upwards relative to the sleeve in the axial direction, the bolt can be separated from the vertical slot by means of self gravity and falls back into the sleeve bolt connecting slot, and at the moment, the vertical section of the bolt is completely positioned in the vertical slot part; the top end of the sleeve is connected with the top end of the steel pipe pile body through a connecting and positioning piece, and the connecting and positioning piece enables 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; a detachable connection structure is arranged between the connection positioning piece and the steel pipe pile body; the construction method comprises the following steps that firstly, a steel pipe pile body and a sleeve are fixedly connected through a bolt, coarse sand is filled in a prefilled material accommodating cavity in advance, then the top end of the steel pipe pile body and the sleeve are fixedly connected through a connecting positioning piece, the whole steel pipe pile body and the sleeve are extruded into soil to a set depth in a static pressure or hammering mode, then the connecting positioning piece at the top end of the steel pipe pile body is taken down, the steel pipe pile body is lifted upwards for a set distance along the axial direction, the bolt is separated from a vertical slot by means of self gravity and falls back into a sleeve bolt connecting groove, then the steel pipe pile body is lowered to the bottommost end again, finally, the sleeve is pulled out, in the sleeve pulling-out process, the coarse sand fills gaps on the periphery of the steel pipe pile body, after the sleeve is pulled out, coarse sand is supplemented to a design elevation at the top end position according to actual conditions, and hammering is compact.

Further is: pre-filling broken stone before coarse sand is filled in the pre-filling material accommodating cavity; the prefilled material accommodating cavity sequentially forms a gravel layer and a coarse sand layer from bottom to top.

Further is: before assembly, the surface of the bolt is coated with lubricant in advance; before piling, the surface of the pile tip is pre-coated with a lubricant.

Further is: during the process of pulling out the sleeve, the sleeve is knocked to assist the coarse sand to separate from the sleeve.

Further is: the top end face of the sleeve is not lower than the top end face of the steel pipe pile body.

Further is: the connecting and positioning piece 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.

Further is: the lower surface of the cap is provided with a cap annular boss extending into the prefill material accommodating cavity, the main body of the cap is provided with a cap cavity with an opening at the top, and the cap cavity is provided with a plurality of sand flowing holes communicated with the prefill material accommodating cavity in the area of the lower surface of the cap annular boss; the top opening of the cap cavity is provided with a cover plate which can be opened and closed. When 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 cavity of the cap before piling.

Further is: the connecting and positioning piece is a clamping piece, the clamping piece is arranged at intervals along the circumferential direction of the steel pipe pile body, and the clamping piece 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.

Further is: the top end face of the sleeve is higher than the top end face of the steel pipe pile body, the connecting positioning piece comprises a first clamping piece connected with the top end of the sleeve and a heightening extension cylinder hermetically connected with the top end of the steel pipe pile body, and the lower end face of the heightening extension cylinder is connected with the top end of the steel pipe pile body through a second clamping piece; the first clamping piece is hinged with a force transmission plate, and one end of the force transmission plate, which is far away from the first clamping piece, is horizontally overlapped at the top end of the heightened extension cylinder; the first fastener is provided with a first clamping groove for vertically inserting the top end of the sleeve, and the second fastener is provided with a second clamping groove for vertically inserting the top end of the steel pipe pile body.

The beneficial effects of the invention are as follows: the steel pipe pile body and the sleeve are coaxial, and the whole steel pipe pile body is extruded into the soil to a set depth in a static pressure or hammering mode, so that the centering arrangement of the steel pipe pile body can be effectively ensured. The invention omits the pre-pore-forming process, does not need to independently fill sand in the later period, and has simple construction; if pile is formed in a hammering mode, coarse sand between the sleeve and the steel pipe pile body can be vibrated and compacted in the hammering process, and the compactness of the pile Zhou Cusha after pile forming is finally improved. The coarse sand filled between the sleeve and the steel pipe pile body is pressed on the annular supporting plate part at the bottom of the steel pipe pile body, and the whole pulling resistance of the steel pipe pile can be improved. The sleeve and other parts can be recycled, only a few sleeves are needed for one project, and the implementation cost is low.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the present invention in its practice.

Fig. 2 is a schematic view of a partially enlarged structure of a connection portion between the bottom end of the steel pipe pile body and the bottom end of the sleeve in the right lower side area of fig. 1.

Fig. 3 is a schematic view of a pile top part partially enlarged structure in fig. 1.

Fig. 4 is a top view of a cap employed in the embodiment shown in fig. 1.

Fig. 5 is a partially enlarged schematic view of a pile top portion according to a second embodiment of the present invention.

Fig. 6 is a partially enlarged schematic view of a pile top according to a third embodiment of the present invention.

The marks in the figure: the steel pipe pile body 1, the annular supporting plate 11, the vertical slot 12, the bolt 2, the sleeve 3, the pile tip 31, the sleeve bolt connecting slot 32, the vertical slot 33, the inclined hole 34, the cap 4, the cap annular boss 41, the cover plate 42, the first clamping groove 51, the second clamping groove 52, the heightened extension cylinder 6, the force transmission plate 7 and the coarse sand 9.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1 to 6, the steel pile structure adopted by the invention comprises a steel pipe pile body 1 which is vertically arranged, an annular supporting plate 11 which is coaxially arranged is fixedly connected to the outer side wall of the bottom end of the steel pipe pile body 1, the annular supporting plate 11 extends obliquely downwards relative to the axis of the steel pipe pile body 1 (the oblique downwards extension is to be understood as a generalized meaning), the radial section of the annular supporting plate 11 can be of an inclined plate structure or an arc plate structure), a sleeve 3 which is coaxial with the annular supporting plate 11 is sleeved on the periphery of the steel pipe pile body 1, the annular supporting plate 11 and the inner wall of the sleeve 3 form sliding fit, the side wall of the lower end of the sleeve 3 is contracted into a sharp shape to form a pile tip 31, a plurality of sleeve bolt connecting grooves 32 are arranged at positions above the pile tip 31 at intervals along the circumferential direction of the sleeve 3, each sleeve bolt connecting groove 32 comprises a vertical groove 33 positioned on the inner side wall of the sleeve 3 and an inclined hole 34 connected to the lower end of the vertical groove 33, the axis of each bolt 34 extends obliquely downwards relative to the vertical groove 33, one end of the inclined hole 34 is far away from the vertical groove 33, the inclined hole 33 is in a direction, the sleeve bolt connecting groove is correspondingly matched with the vertical section 2, and the vertical section is provided with the vertical section 12; when the steel pipe pile body 1 and the sleeve 3 are fixedly connected through the bolt 2, the upper end of the vertical section of the bolt is positioned in the vertical slot 12, the lower end of the inclined section of the bolt is positioned in the inclined hole part 34, and the outer wall of the steel pipe pile body 1, the annular supporting plate 11 and the inner wall of the sleeve 3 form a prefilled material accommodating cavity; when the steel pipe pile body 1 moves upwards relative to the sleeve 3 along the axial direction, the bolt 2 can be separated from the vertical slot 12 by means of the gravity of the bolt 2 and fall back into the sleeve bolt connecting slot 32, and the vertical section of the bolt is completely positioned in the vertical slot part 33 at the moment (namely, the whole bolt 2 is completely hidden in the sleeve bolt connecting slot 32, the bolt 2 does not have a protruding part relative to the inner wall of the sleeve 3, and the sleeve 3 can be pulled out upwards at the moment); the top end of the sleeve 3 is connected with the top end of the steel pipe pile body 1 through a connecting and positioning piece, and the connecting and positioning piece 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 locating piece and the steel pipe pile body 1 are of a detachable connecting structure. The top end of the sleeve 3 and the top end of the steel pipe pile body 1 are in a first state of being relatively connected and fixed, namely that the top end of the sleeve 3 and the top end of the steel pipe pile body 1 can be integrally stressed when the pile is pressed, and the top end of the sleeve 3 and the top end of the steel pipe pile body 1 are in a second state of being relatively separated, namely that the sleeve 3 can be pulled out upwards after the pile is pressed, and cannot be influenced by the steel pipe pile body 1. The connection locating piece and the steel pipe pile body 1 are of a detachable connection structure, namely the connection locating piece can be taken down from the steel pipe pile body 1 after pile pressing is completed, and follow-up construction cannot be affected. For convenient assembly and recycling, the connecting positioning piece and the sleeve 3 are also usually of a detachable connecting structure. The annular supporting plate 11, the bolt 2, the sleeve 3 and the connecting positioning piece are made of materials meeting the strength requirement, and are usually made of steel materials.

During implementation, firstly, the steel pipe pile body 1 and the sleeve 3 are fixedly connected through the bolt 2, the bolt 2 cannot naturally fall under the limiting action of the vertical slot 12, at this time, the outer wall of the steel pipe pile body 1, the annular supporting plate 11 and the inner wall of the sleeve 3 form a prefill material accommodating cavity, coarse sand 9 (preferably, crushed stone is filled firstly and coarse sand 9 is filled later) is filled in the prefill material accommodating cavity in advance, then the top ends are fixedly connected through a connecting positioning piece, the steel pipe pile body 1 and the sleeve 3 are integrally extruded into soil to a set depth in a static pressure or hammering mode, then the connecting positioning piece at the top end of the steel pipe pile body 1 is taken down, the steel pipe pile body 1 is lifted up by a set distance along the axial direction (determined according to the vertical depth of the vertical slot 12), the bolt 2 is separated from the vertical slot 12 by means of self gravity and falls back into the sleeve bolt connecting groove 32, then the steel pipe pile body 1 is lowered down to the bottommost end again, and finally, in the sleeve 3 is pulled out, in the process of pulling out the sleeve 3, the coarse sand 9 can automatically fill gaps (space formed after the sleeve 3 is pulled out), the sleeve 3 is pulled out, and the pile body 1 is compacted to the actual position according to the actual design condition. During the process of pulling out the sleeve 3, the sleeve 3 can be knocked at the same time to assist the separation of the coarse sand 9 from the sleeve 3. The purpose of the gravel loading and coarse sand loading 9 is to prevent the coarse sand 9 from falling to the sleeve bolt connecting groove 32 from the gap of the outer edge of the annular supporting plate 11 so as not to influence the automatic falling of the bolt 2. It will be appreciated that the grit 9 may also be directly packed when the fit clearance between the outer edge of the annular support plate 11 and the inner wall of the sleeve 3 is sufficiently small or both are in contact (grit 9 cannot enter naturally). To facilitate the automatic falling back of the plug pin 2, the outer surface of the plug pin 2 may be pre-coated with a lubricant.

To reduce the frost heaving effect, the surface of the pile tip 31 may be pre-coated with a lubricant prior to piling.

In order to ensure that the prefilled material accommodating cavity has the coarse sand volume as large as possible when the coarse sand 9 is preloaded, the top end face of the sleeve 3 is not lower than the top end face of the steel pipe pile body 1. In order to better protect the steel pipe pile body 1, it may be further preferable that the top end surface of the sleeve 3 is higher than the top end surface of the steel pipe pile body 1.

For the connecting and positioning element, referring to fig. 3, the connecting and positioning element may be a cap 4 in a whole structure, and 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. It should be noted that in some embodiments, the first annular clamping groove may have a single-side wall structure, and the second annular clamping groove may also have a single-side wall structure, for example, in the embodiment shown in fig. 3, the second annular clamping groove omits a side wall near the center of the steel pipe pile body 1. The cap 4 can also play a role in protecting the steel pipe pile body 1.

In order to further improve the pre-loading capacity of coarse sand 9, referring to fig. 3 and 4, the top end face of sleeve 3 in the invention is not lower than the top end face of steel pipe pile body 1, the lower surface of cap 4 has cap annular boss 41 extending into the prefilled material accommodating cavity, the main body of cap 4 has cap cavity with top opening, the cap cavity is provided with a plurality of sand flowing holes communicated with the prefilled material accommodating cavity in the area of the lower surface of cap annular boss 41, the sand flowing holes are distributed evenly along the circumferential direction; the top opening of the cap cavity is provided with a cover plate 42 which can be opened and closed; the cover 42 may be generally hinged to the cover by a rotatable hinge, although in some embodiments, it may be replaced by a removable hinge. In the implementation process, coarse sand 9 can be preloaded in the cavity of the cap, the structure is preferably formed into a pile by 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 vibrate tightly in the hammering process, 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 can be lowered, and the coarse sand 9 in the cavity of the cap can be supplemented between the inner wall of the sleeve 3 and the outer wall of the steel pipe pile body 1 through the falling of the sand flowing holes. This embodiment also ultimately promotes the tightness of the post-staked stake Zhou Cusha.

Referring to fig. 5, in other embodiments, the connection positioning member may be a plurality of fastening members, which are arranged at intervals along the circumferential direction of the steel pipe pile body 1, and each fastening member has a first fastening groove 51 for vertically inserting the top end of the sleeve 3 and a second fastening groove 52 for vertically inserting the top end of the steel pipe pile body 1. When the assembly is implemented, the clamping piece is directly clamped with the wall of the top end of the sleeve 3 and the wall of the top end of the steel pipe pile body 1 at the same time, and the assembly and the disassembly are convenient.

In order to increase the preassembly capacity of the preassembled coarse sand 9, referring to fig. 6, in other embodiments, the top end surface of the sleeve 3 may be designed to be higher than the top end surface of the steel pipe pile body 1, and the connection positioning member includes a first fastening member connected to the top end of the sleeve 3 and a heightened extension tube 6 hermetically connected to the top end of the steel pipe pile body 1, where the lower end surface of the heightened extension tube 6 is connected to the top end of the steel pipe pile body 1 through a second fastening member; the first clamping piece is hinged with a force transmission plate 7, and one end of the force transmission plate 7, which is far away from the first clamping piece, is horizontally overlapped at the top end of the heightening extension cylinder 6; the first fastener is provided with a first clamping groove 51 for vertically inserting the top end of the sleeve 3, and the second fastener is provided with a second clamping groove 52 for vertically inserting the top end of the steel pipe pile body 1.

Claims (9)

1. The construction method of the engineering pile suitable for the frozen soil area adopts a steel pile structure comprising a vertically arranged steel pipe pile body (1), and is characterized in that: the outer side wall of the bottom end of the steel pipe pile body (1) is fixedly connected with an annular supporting plate (11) which is coaxially arranged, the annular supporting plate (11) extends obliquely downwards relative to the axis of the steel pipe pile body (1), a sleeve (3) which is coaxial with the annular supporting plate is sleeved on the periphery of the steel pipe pile body (1), the annular supporting plate (11) and the inner wall of the sleeve (3) form sliding fit, the side wall of the lower end of the sleeve (3) contracts into a sharp shape to form a pile tip (31), sleeve bolt connecting grooves (32) are arranged above the pile tip (31) on the inner side wall of the lower end of the sleeve (3), the sleeve bolt connecting grooves (32) are distributed at intervals along the circumferential direction of the sleeve (3), each sleeve bolt connecting groove (32) comprises a vertical groove (33) which is positioned on the inner side wall of the sleeve (3) and an inclined hole part (34) which is connected to the lower end of the vertical groove (33), the axis of the inclined hole part (34) extends obliquely downwards relative to the vertical groove part (33), one end of the inclined hole part (34) far away from the vertical groove part (33) is of the sleeve bolt connecting groove (32) is of a closed structure, a plurality of bolts (32) are correspondingly arranged along the circumferential direction of the sleeve bolt connecting grooves (32), and the inclined bolt connecting grooves (33) are formed by the inclined bolt connecting sections (2) and the vertical bolt connecting sections (2), the lower surface of the annular supporting plate (11) is provided with a vertical slot (12) which is matched with the vertical section of the bolt; when the steel pipe pile body (1) is fixedly connected with the sleeve (3) through the bolt (2), the upper end of the vertical section of the bolt is positioned in the vertical slot (12), the lower end of the inclined section of the bolt is positioned in the inclined hole part (34), and the outer wall of the steel pipe pile body (1), the annular supporting plate (11) and the inner wall of the sleeve (3) form a prefilled material accommodating cavity; when the steel pipe pile body (1) moves upwards along the axial direction relative to the sleeve (3), the bolt (2) can be separated from the vertical slot (12) by means of self gravity and falls back into the sleeve bolt connecting slot (32), and at the moment, the vertical section of the bolt is completely positioned in the vertical slot part (33); the top end of the sleeve (3) is connected with the top end of the steel pipe pile body (1) through a connecting and positioning piece, and the connecting and positioning piece 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; a detachable connection structure is arranged between the connection positioning piece and the steel pipe pile body (1); the construction method comprises the following steps that firstly, a steel pipe pile body (1) and a sleeve (3) are fixedly connected through a bolt (2), coarse sand (9) is filled in a prefilled material accommodating cavity in advance, then the top end is fixedly connected through a connecting locating piece, the steel pipe pile body (1) and the sleeve (3) are integrally extruded into soil to a set depth in a static pressure or hammering mode, then the connecting locating piece at the top end of the steel pipe pile body (1) is taken down, the steel pipe pile body (1) is lifted upwards for a set distance along the axial direction, the bolt (2) is separated from a vertical slot (12) by means of self gravity and falls back into a sleeve bolt connecting groove (32), then the steel pipe pile body (1) is lowered to the bottommost end again, finally, the sleeve (3) is pulled out outwards, gaps on the periphery of the steel pipe pile body (1) are filled with the coarse sand (9), after the sleeve (3) is pulled out, the coarse sand (9) is supplemented to a designed elevation at the top end position according to actual conditions, and is compact.

2. The construction method for engineering piles adapted to frozen soil areas according to claim 1, wherein: pre-filling broken stone before coarse sand (9) is filled in the pre-filling material accommodating cavity; the prefilled material accommodating cavity sequentially forms a gravel layer and a coarse sand layer from bottom to top.

3. The construction method for engineering piles adapted to frozen soil areas according to claim 1, wherein: before assembly, the surface of the bolt (2) is coated with lubricant in advance; the surface of the pile tip (31) is pre-coated with a lubricant prior to piling.

4. The construction method for engineering piles adapted to frozen soil areas according to claim 1, wherein: during the process of pulling out the sleeve (3), the sleeve (3) is knocked at the same time to assist the coarse sand (9) to separate from the sleeve (3).

5. The construction method for engineering piles adapted to frozen soil areas according to 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. A method of construction of an engineered pile for use in a frozen earth area as in any of claims 1 to 5, wherein: the connecting and positioning piece is a cap (4), and 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 construction method for engineering piles adapted to frozen soil areas as claimed in claim 6, wherein: the lower surface of the cap (4) is provided with a cap annular boss (41) extending into the prefilled material accommodating cavity, the main body of the cap (4) is provided with a cap cavity with an opening at the top, and the cap cavity is provided with a plurality of sand flowing holes communicated with the prefilled material accommodating cavity in the area of the lower surface of the cap annular boss (41); the top opening of the cap cavity is provided with a cover plate (42) which can be opened and closed; during construction, after the top end of the sleeve (3) is connected and fixed with the top end of the steel pipe pile body (1) by the cap (4), coarse sand (9) is also preloaded in the cavity of the cap before piling.

8. A method of construction of an engineered pile for use in a frozen earth area as in any of claims 1 to 5, wherein: the connecting and positioning piece is a plurality of clamping pieces which are arranged at intervals along the circumferential direction of the steel pipe pile body (1), and each clamping piece 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. A method of construction of an engineered pile for use in a frozen earth area as in any 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 piece comprises a first clamping piece connected with the top end of the sleeve (3) and a heightening extension cylinder (6) hermetically connected with the top end of the steel pipe pile body (1), and the lower end surface of the heightening extension cylinder (6) is connected with the top end of the steel pipe pile body (1) through a second clamping piece; the first clamping piece is hinged with a force transmission plate (7), and one end of the force transmission plate (7) far away from the first clamping piece is horizontally lapped at the top end of the heightening extension cylinder (6); the first fastener is provided with a first clamping groove (51) for vertically inserting the top end of the sleeve (3), and the second fastener is provided with a second clamping groove (52) for vertically inserting the top end of the steel pipe pile body (1).