One-time pile-forming construction method for foundation pit top variable cross-section semicircular support secant piles

Abstract

The invention relates to the technical field of secant piles, and discloses a foundation pit top variable cross-section semicircular support secant pile one-time pile forming construction method which comprises the following construction steps that (1) a plurality of plain pile holes are formed; (2) putting a semi-cylindrical die into the plain pile hole; (3) concrete is poured into the plain pile holes; (4) the semi-cylindrical molds are pulled out of the plain pile holes, plain pile bodies are formed, and plain pile empty areas and plain pile steps are arranged on the plain pile bodies; (5) forming meat pile holes; (6) a reinforcement cage is put into the reinforced pile hole; (7) putting a semi-cylindrical die into the meat pile hole; (8) concrete is poured into the meat pile holes; (9) the semi-cylindrical mold is pulled out of the meat pile hole, a meat pile body is formed, and a meat pile empty area and a meat pile step are arranged on the meat pile body; the two sides of the reinforced pile body are respectively engaged with the plain pile body to form an engaged pile with an integrated structure; matching of the secant pile and the cover excavation top plate is achieved, concrete does not need to be chiseled away, one-time forming construction is achieved, the construction efficiency is improved, and the construction cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of support bite piles, in particular to a one-time pile construction method for semicircular support bite piles with variable cross-sections at the top of a foundation pit. Background Art

[0002] The reverse excavation method is to first construct the excavation top plate of the excavation structure after the construction of the retaining structure and supporting piles is completed, restore the upper road traffic, and then excavate and construct the lower structure below the excavation top plate. According to the design requirements, both sides of the excavation top plate are located on the retaining structure.

[0003] The retaining structure is an interlocking pile. In order to achieve overlapping cooperation between the cover excavation top plate and the interlocking pile, it is necessary to form a pile void area in the interlocking pile, and form a pile step at the bottom of the pile void area. The two sides of the cover excavation top plate are embedded in the pile void area and overlapped on the pile step.

[0004] In the existing technology, since the interlocking piles are poured into the ground at one time, in order to form pile voids and pile steps on the interlocking piles, it is necessary to chisel out the upper concrete of the interlocking piles after the foundation pit is excavated to form the pile voids and pile steps. This is time-consuming, slows down construction efficiency, and increases construction costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a one-time pile construction method for variable-section semicircular support interlocking piles on the top of a foundation pit, aiming to solve the problem in the prior art that concrete needs to be chiseled out on the interlocking piles to form a pile void area, resulting in low construction efficiency.

[0006] The present invention is achieved by a one-time pile construction method for semicircular support interlocking piles with variable cross-sections at the top of a foundation pit, comprising the following construction steps:

[0007] 1) Rotatingly excavating a plurality of pile holes on the periphery of the foundation pit, wherein the plurality of pile holes are spaced apart along the circumference of the foundation pit;

[0008] 2) inserting a semi-cylindrical mold into the upper part of the pile hole;

[0009] 3) pouring concrete into the pile hole, so that the concrete fills the pile hole and wraps around the outside of the semi-cylindrical mold;

[0010] 4) Pulling the semi-cylindrical form out of the pile hole, the concrete is formed into a pile body in the pile hole, the pile body has a pile hollow area, and the bottom of the pile hollow area has a pile step;

[0011] 5) Rotating and digging between adjacent plain pile bodies to form raw pile holes;

[0012] 6) Inserting a steel cage into the pile hole, wherein the upper portion of the steel cage has a cage hollow area;

[0013] 7) Insert a semi-cylindrical mold into the upper part of the meat pile hole, and place the semi-cylindrical mold in the cage empty area;

[0014] 8) pouring concrete into the pile hole, the concrete filling the pile hole and wrapping the semi-cylindrical mold;

[0015] 9) Pull the semi-cylindrical form out of the meat pile hole, and the concrete is formed into a meat pile body in the meat pile hole. The meat pile body has a meat pile empty area, and the bottom of the meat pile empty area has a meat pile step; the two sides of the meat pile body are respectively engaged with the plain pile body to form an integrated structure of the engaged pile, the meat pile empty area is connected with the plain pile empty area to form a pile empty area, and the plain pile step is flush with the meat pile step to form a pile step.

[0016] Furthermore, in the construction step 1), before the plurality of pile holes are drilled, two guide walls are constructed on the construction site, with a guide groove between the two guide walls, and the plurality of pile holes are drilled in the guide groove.

[0017] Furthermore, in the construction step 2), before the semi-cylindrical mold is lowered into the plain pile hole, a release agent is coated on the outer periphery of the semi-cylindrical mold; in the construction step 7), before the semi-cylindrical mold is lowered into the meat pile hole, a release agent is coated on the outer periphery of the semi-cylindrical mold.

[0018] Furthermore, the interior of the semi-cylindrical mold has a semi-cylindrical cavity, the bottom of the semi-cylindrical cavity is closed, and the top of the semi-cylindrical cavity has a top opening;

[0019] In the construction step 2), when the semi-cylindrical mold is lowered into the plain pile hole, and in the construction step 7), when the semi-cylindrical mold is lowered into the meat pile hole, the semi-cylindrical cavity is filled with sandbags and the top opening is arranged above the ground.

[0020] Furthermore, the top of the semi-cylindrical form has a transverse hole. In the construction step 2), after the semi-cylindrical form is placed in the pile hole, a short steel bar is passed through the transverse hole to fix the semi-cylindrical form in the pile hole.

[0021] In the construction step 7), after the semi-cylindrical form is placed in the pile hole, short steel bars are used to pass through the transverse holes to fix the semi-cylindrical form in the pile hole.

[0022] Furthermore, the semi-cylindrical mold includes a semi-circular arc-shaped arc plate and a straight plate-shaped straight plate, the two ends of the arc plate are respectively connected to the two ends of the straight plate, the straight plate and the arc plate enclose the semi-cylindrical cavity, and the bottom of the semi-cylindrical cavity is covered with a bottom plate;

[0023] In the construction step 2), after the semi-cylindrical form is relatively fixed in the plain pile hole, the arc-shaped plate abuts against the inner wall of the plain pile hole, and the straight plate is arranged in a suspended longitudinal position; in the construction step 7), after the semi-cylindrical form is relatively fixed in the meat pile hole, the arc-shaped plate abuts against the inner wall of the meat pile hole, and the straight plate is arranged in a suspended longitudinal position.

[0024] Furthermore, in the construction step 6), the steel cage includes a full circle segment and a semicircular segment located above the full circle segment, the cage empty area is formed on the semicircular segment, and there is a cage step between the semicircular segment and the full circle segment; in the construction step 7), when the semi-cylindrical mold is placed in the pile hole, the bottom of the semi-cylindrical mold abuts against the cage step.

[0025] Furthermore, a longitudinally arranged web is provided in the middle of the semi-cylindrical cavity, one side of the web is butted against the straight plate, and the other side of the web is butted against the curved plate; a plurality of transversely arranged curved strips are provided in the semi-cylindrical cavity, the plurality of curved strips are arranged at intervals along the height direction of the semi-cylindrical cavity, and the curved strips are arranged to be bent in the same direction along the bending direction of the curved plate;

[0026] The arc strip is butted against the inner side wall of the arc plate, the two ends of the arc strip are butted against the two ends of the straight plate respectively, and the middle portion of the arc strip passes through the other side of the web.

[0027] Furthermore, the web divides the semi-cylindrical mold into two separated divided cavities, and an elastic plate is provided in the divided cavity. The two ends of the top of the elastic plate are fixedly connected to the web and the arc-shaped plate respectively, and the two sides and the bottom of the elastic plate are freely arranged, and the bottom of the elastic plate is located above the bottom plate;

[0028] The elastic plate divides the partition cavity into a plurality of elastic cavities arranged at intervals. Along the extension direction of the elastic plate from top to bottom, the elastic plate is arranged obliquely toward the straight plate. The sandbag is filled in the elastic cavity and squeezes the elastic plate away from the web to elastically deform.

[0029] Furthermore, the elastic plate has an inward side surface facing the web, and a plurality of arc-shaped steps are convexly provided on the inward side surface, and the arc-shaped steps are arranged to protrude toward the web; the sandbag abuts against the arc-shaped steps, squeezing the elastic plate away from the web to elastically deform.

[0030] Compared with the prior art, the one-time pile construction method of the semicircular support interlocking pile with variable cross-section at the top of the foundation pit provided by the present invention has the following advantages:

[0031] 1) In the process of forming the plain pile body and the concrete pile body, a semi-cylindrical mold is implanted to form a plain pile hollow area on the plain pile body and a concrete pile hollow area on the concrete pile body. The finally formed occlusal pile has a pile hollow area and a pile step, so that the occlusal pile is matched with the cover and excavation top plate. There is no need to remove concrete, and one-time forming construction is achieved, thereby improving construction efficiency and saving construction costs.

[0032] 2) During the forming process of the pile body, the steel cage forms a cage hollow area, which can cooperate with the semi-cylindrical mold to ensure the overall structure and rigidity of the steel cage and the overall structure and rigidity of the occlusal pile;

[0033] 3) By implanting a semi-cylindrical mold, the interlocking pile can be constructed in one piece, eliminating the need for the subsequent concrete chiseling process, saving energy and materials. At the same time, it eliminates the cost of transporting concrete waste, the cost of manual chiseling, and the construction time, saving costs and improving the level of green and civilized construction on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the process of the one-time pile construction method of the variable-section semicircular support occlusal piles at the top of the foundation pit provided by the present invention;

[0035] Figure 2 This is a three-dimensional schematic diagram of the steel cage provided by the present invention being lowered into the pile hole;

[0036] Figure 3 It is a three-dimensional schematic diagram of the combination of the plain pile body and the meat pile body provided by the present invention.

[0037] Figure 4 It is a three-dimensional schematic diagram of the semi-cylindrical mold provided by the present invention;

[0038] Figure 5 This is a partial three-dimensional schematic diagram of the semi-cylindrical mold provided by the present invention:

[0039] Figure 6 It is a schematic diagram of the interior of the semi-cylindrical cavity provided by the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] The implementation of the present invention is described in detail below with reference to specific embodiments.

[0042] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "up", "down", "left", "right", etc. indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] Reference Figure 1-6 The figure shows a preferred embodiment of the present invention.

[0044] The one-time pile construction method of semicircular support interlocking piles with variable cross-section at the top of the foundation pit includes the following construction steps:

[0045] 1) Rotary excavation is performed on the outer circumference of the foundation pit to form a plurality of pile holes, and the plurality of pile holes are arranged at intervals along the circumference of the foundation pit;

[0046] 2) Insert a semi-cylindrical mold 500 into the upper part of the pile hole, so that the semi-cylindrical mold 500 occupies the space in the pile hole;

[0047] 3) Pour concrete into the pile hole. The concrete fills the pile hole and wraps around the outside of the semi-cylindrical mold 500.

[0048] 4) Pulling the semi-cylindrical mold 500 out of the pile hole, the concrete is formed into a pile body 300 in the pile hole, the pile body 300 has a pile hollow area 303, and the bottom of the pile hollow area 303 has a pile step 304;

[0049] 5) Rotating and digging between adjacent plain pile bodies 300 to form raw pile holes;

[0050] 6) Insert the steel cage 200 into the pile hole, and the upper part of the steel cage 200 has a cage hollow area 203;

[0051] 7) Insert a semi-cylindrical mold 500 into the upper middle of the pile hole. The semi-cylindrical mold 500 is placed in the cage empty area 203 to achieve the cooperation between the semi-cylindrical mold 500 and the steel cage 200 without interference.

[0052] 8) Pour concrete into the pile hole, the concrete fills the pile hole and wraps the semi-cylindrical mold 500;

[0053] 9) Pull out the semi-cylindrical mold 500 from the meat pile hole, and the concrete is formed into a meat pile body 400 in the meat pile hole. The meat pile body 400 has a meat pile empty area 403, and the bottom of the meat pile empty area 403 has a meat pile step 404; the two sides of the meat pile body 400 are respectively engaged with the plain pile body 300 to form an integrated structure of the bite pile, the meat pile empty area 403 is connected with the plain pile empty area 303 to form a pile empty area, and the plain pile step 304 is flush with the meat pile step 404 to form a pile step.

[0054] The one-time pile construction method of the semicircular support interlocking piles with variable cross-section at the top of the foundation pit provided above has the following advantages:

[0055] 1) During the forming process of the plain pile body 300 and the concrete pile body 400, a semi-cylindrical mold 500 is implanted to form a plain pile hollow area 303 on the plain pile body 300 and a concrete pile hollow area 403 on the concrete pile body 400. The finally formed occlusal pile has a pile hollow area and a pile step, so that the occlusal pile is matched with the cover and excavation top plate. There is no need to remove concrete, and one-time forming construction is achieved, thereby improving construction efficiency and saving construction costs.

[0056] 2) During the forming process of the pile body 400, the steel cage 200 forms a cage hollow area 203, which can cooperate with the semi-cylindrical mold 500 to ensure the overall structure and rigidity of the steel cage 200 and the overall structure and rigidity of the occlusal pile;

[0057] 3) By implanting the semi-cylindrical form 500, the interlocking pile can be constructed in one piece, eliminating the need for the subsequent concrete chiseling process, saving energy and materials. At the same time, it eliminates the cost of shipping concrete waste, the cost of manual chiseling, and the construction time, thus saving costs and improving the level of green and civilized construction on site.

[0058] In this embodiment, in construction step 1), before rotary drilling of a plurality of raw pile holes, two guide walls 100 are constructed and formed on the construction site, with a guide groove being defined between the two guide walls 100, and a plurality of raw pile holes are rotary drilled in the guide groove.

[0059] Before construction, the construction site was leveled and compacted using an excavator, and weak areas were replaced and compacted. Based on the coordinates provided in the design drawings, the centerline coordinates of the interlocking piles were calculated by 100mm. A total station and level were used to stake out the ground guide control points and establish retaining piles. This served as the control centerline for the guide wall 100 construction.

[0060] After completing the pile position measurement and layout, the guide groove of the guide wall 100 is excavated by combining machinery with manual labor, and the center line is introduced under the guide groove to control the formwork construction. The guide wall 100 steel bars are processed and tied according to the design requirements, steel formwork is used for support, and steel pipe support and reinforcement are used.

[0061] In this embodiment, in construction step 2), before the semi-cylindrical mold 500 is lowered into the plain pile hole, a release agent is coated on the outer periphery of the semi-cylindrical mold 500, so that the semi-cylindrical mold 500 can be separated from the plain pile body 300 in the subsequent process; in construction step 7), before the semi-cylindrical mold 500 is lowered into the meat pile hole, a release agent is coated on the outer periphery of the semi-cylindrical mold 500, so that the semi-cylindrical mold 500 can be separated from the meat pile body 400 in the subsequent process.

[0062] In this embodiment, the interior of the semi-cylindrical mold 500 has a semi-cylindrical cavity 505, the bottom of the semi-cylindrical cavity 505 is closed, and the top of the semi-cylindrical cavity 505 has a top opening; in construction step 2), when the semi-cylindrical mold 500 is lowered into the plain pile hole, and in construction step 7), when the semi-cylindrical mold 500 is lowered into the meat pile hole, the semi-cylindrical cavity 505 is filled with sandbags 603, and the top opening is arranged above the ground.

[0063] The bottom of the semi-cylindrical mold 500 is sealed to prevent concrete from entering the semi-cylindrical cavity 505 during the concrete pouring process. Sandbags 603 are filled in the semi-cylindrical cavity 505 to increase the weight of the semi-cylindrical mold 500, facilitating its sinking during placement and preventing it from floating during subsequent concrete pouring.

[0064] In this embodiment, the top of the semi-cylindrical form 500 has a transverse hole. In construction step 2), after the semi-cylindrical form 500 is placed in the pile hole, a short steel bar is passed through the transverse hole to fix the semi-cylindrical form 500 in the pile hole.

[0065] In construction step 7), after the semi-cylindrical form 500 is placed in the pile hole, short steel bars are used to pass through the transverse holes to fix the semi-cylindrical form 500 in the pile hole.

[0066] In this way, when the semi-cylindrical form 500 is lowered into the plain pile hole or the meat pile hole, the position of the semi-cylindrical form 500 can be fixed by passing short steel bars through the semi-cylindrical form 500, thereby avoiding the displacement of the semi-cylindrical form 500 during the subsequent concrete pouring process.

[0067] In this embodiment, the semi-cylindrical mold 500 includes a semi-circular arc-shaped plate 502 and a straight plate 501. The two ends of the arc-shaped plate 502 are respectively connected to the two ends of the straight plate 501. The straight plate 501 and the arc-shaped plate 502 enclose a semi-cylindrical cavity 505. The bottom of the semi-cylindrical cavity 505 is sealed with a bottom plate 507.

[0068] In construction step 2), when the semi-cylindrical mold 500 is relatively fixed in the plain pile hole, the curved plate 502 abuts against the inner wall of the plain pile hole, and the straight plate 501 is arranged in a suspended longitudinal position; in construction step 7), when the semi-cylindrical mold 500 is relatively fixed in the meat pile hole, the curved plate 502 abuts against the inner wall of the meat pile hole, and the straight plate 501 is arranged in a suspended longitudinal position.

[0069] The straight plate 501 and the curved plate 502 shape the entire semi-cylindrical mold 500. The subsequently formed meat pile empty area 403 and plain pile empty area 303 are respectively consistent with the shape of the semi-cylindrical mold 500. The bottom plate 507 can seal the bottom of the semi-cylindrical cavity 505 to prevent concrete from entering the semi-cylindrical cavity 505.

[0070] In this embodiment, in construction step 6), the steel cage 200 includes a full-circle segment 202 and a semi-circle segment 201 located above the full-circle segment 202, a cage void area 203 is formed on the semi-circle segment 201, and a cage step 204 is provided between the semi-circle segment 201 and the full-circle segment 202; in construction step 7), after the semi-cylindrical mold 500 is placed in the pile hole, the bottom of the semi-cylindrical mold 500 abuts against the cage step 204.

[0071] The steel cage 200 is integrally formed, ensuring its overall structure and rigidity. Multiple circular reinforcement bars are connected to multiple main bars to form the initial structure of the steel bar. Multiple main bars are arranged circumferentially around the reinforcement bars. Stirrups are then wrapped around the periphery of the initial structure to complete the steel cage 200.

[0072] In this embodiment, a longitudinally arranged web 503 is provided in the middle of the semi-cylindrical cavity 505. One side of the web 503 is connected to the straight plate 501, and the other side of the web 503 is connected to the curved plate 502. A plurality of transversely arranged curved strips 504 are provided in the semi-cylindrical cavity 505. The plurality of curved strips 504 are arranged at intervals along the height direction of the semi-cylindrical cavity 505 and are arranged to be curved in the same direction along the curvature direction of the curved plate 502.

[0073] The arc strip 504 is butted against the inner side wall of the arc plate 502 , and the two ends of the arc strip 504 are butted against the two ends of the straight plate 501 , respectively, and the middle portion of the arc strip 504 passes through the other side of the web 503 .

[0074] The web 503 is used to shape the middle part of the curved plate 502 to avoid deformation between the curved plate 502 and the straight plate 501. Secondly, multiple curved strips 504 are arranged along the bending direction of the curved plate 502 to ensure that the bending direction of the curved plate 502 is shaped.

[0075] In this embodiment, the web 503 divides the semi-cylindrical mold 500 into two separated dividing cavities, and an elastic plate 601 is provided in the dividing cavity. The two ends of the top of the elastic plate 601 are fixedly connected to the web 503 and the arc plate 502 respectively. The two sides and the bottom of the elastic plate 601 are freely arranged, and the bottom of the elastic plate 601 is located above the bottom plate 507.

[0076] The elastic plate 601 divides the dividing cavity into a plurality of elastic cavities 600 arranged at intervals. Along the top-down extension direction of the elastic plate 601, the elastic plate 601 is arranged tilted toward the straight plate 501. The sandbag 603 is filled in the elastic cavity 600 and squeezes the elastic plate 601 away from the web 503 to elastically deform.

[0077] When the semi-cylindrical mold 500 is placed in the plain pile hole or the meat pile hole, its curved plate 502 abuts against the inner wall of the plain pile hole or the meat pile hole. Since the elastic plate 601 is arranged inclined toward the straight plate 501, when the elastic cavity 600 is filled with sandbags 603, the sandbags 603 squeeze the elastic plate 601 away from the web 503 and deform it. The semi-cylindrical mold 500 can apply an extrusion force toward the plain pile hole or the meat pile hole to make the curved plate 502 better abut against the inner wall of the plain pile hole or the meat pile hole.

[0078] In this embodiment, the elastic plate 601 has an inward side surface facing the web 503, and a plurality of arc-shaped steps 602 are convexly provided on the inward side surface, and the arc-shaped steps 602 are arranged to protrude toward the web 503; the sandbag 603 abuts against the arc-shaped steps 602, squeezing the elastic plate 601 away from the web 503 to elastically deform.

[0079] By arranging multiple arc-shaped steps 602, the sandbag 603 can press against the elastic plate 601 at multiple positions and form a larger contact area, which can better drive the elastic plate 601 to elastically deform away from the web 503, so that the arc-shaped plate 502 can better contact the inner wall of the plain pile hole or the meat pile hole.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A one-time pile construction method for variable-section semicircular support bite piles at the top of foundation pit, characterized in that: The construction steps include: 1) Rotatingly excavating a plurality of pile holes on the outer circumference of the foundation pit, wherein the plurality of pile holes are arranged at intervals along the circumference of the foundation pit; 2) inserting a semi-cylindrical mold into the upper part of the pile hole; 3) pouring concrete into the pile hole, so that the concrete fills the pile hole and wraps around the outside of the semi-cylindrical mold; 4) Pulling the semi-cylindrical mold out of the pile hole, the concrete is formed into a pile body in the pile hole, the pile body has a pile hollow area, and the bottom of the pile hollow area has a pile step; 5) Rotatingly digging between adjacent plain pile bodies to form plain pile holes; 6) A steel cage is placed in the pile hole, and the upper part of the steel cage has a cage hollow area; 7) Insert a semi-cylindrical mold into the upper part of the meat pile hole, and place the semi-cylindrical mold in the cage empty area; 8) pouring concrete into the pile hole, the concrete fills the pile hole and wraps the semi-cylindrical mold; 9) Pull the semi-cylindrical mold out of the meat pile hole, and the concrete is formed into a meat pile body in the meat pile hole. The meat pile body is provided with a meat pile empty area, and the bottom of the meat pile empty area is provided with a meat pile step; the two sides of the meat pile body are respectively engaged with the plain pile body to form an engaged pile with an integrated structure, the meat pile empty area is connected with the plain pile empty area to form a pile empty area, and the plain pile step is flush with the meat pile step to form a pile step.

2. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 1 is characterized in that: In the construction step 1), before the plurality of raw pile holes are excavated, two guide walls are constructed on the construction site, a guide groove is provided between the two guide walls, and a plurality of raw pile holes are excavated in the guide groove.

3. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 1 is characterized in that: In the construction step 2), before the semi-cylindrical mold is lowered into the plain pile hole, a release agent is coated on the outer circumference of the semi-cylindrical mold; in the construction step 7), before the semi-cylindrical mold is lowered into the meat pile hole, a release agent is coated on the outer circumference of the semi-cylindrical mold.

4. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit according to any one of claims 1 to 3, characterized in that: The semi-cylindrical mold has a semi-cylindrical cavity inside, the bottom of the semi-cylindrical cavity is closed, and the top of the semi-cylindrical cavity has a top opening; In the construction step 2), when the semi-cylindrical mold is lowered into the plain pile hole, and in the construction step 7), when the semi-cylindrical mold is lowered into the meat pile hole, the semi-cylindrical cavity is filled with sandbags and the top opening is arranged above the ground.

5. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit according to any one of claims 1 to 3, characterized in that: The top of the semi-cylindrical form has a transverse hole. In the construction step 2), after the semi-cylindrical form is placed in the pile hole, a short steel bar is passed through the transverse hole to fix the semi-cylindrical form in the pile hole; In the construction step 7), after the semi-cylindrical form is placed in the pile hole, short steel bars are passed through the transverse holes to fix the semi-cylindrical form in the pile hole.

6. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 4 is characterized in that: The semi-cylindrical mold includes a semi-circular arc-shaped arc plate and a straight plate, the two ends of the arc-shaped plate are respectively connected to the two ends of the straight plate, the straight plate and the arc-shaped plate are enclosed to form the semi-cylindrical cavity, and the bottom of the semi-cylindrical cavity is covered with a bottom plate; In the construction step 2), when the semi-cylindrical mold is relatively fixed in the plain pile hole, the arc plate abuts against the inner wall of the plain pile hole, and the straight plate is suspended longitudinally arranged; in the construction step 7), when the semi-cylindrical mold is relatively fixed in the meat pile hole, the arc plate abuts against the inner wall of the meat pile hole, and the straight plate is suspended longitudinally arranged.

7. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit according to any one of claims 1 to 3, characterized in that: In the construction step 6), the steel cage includes a full circle segment and a semicircular segment located above the full circle segment, the cage hollow area is formed on the semicircular segment, and a cage step is provided between the semicircular segment and the full circle segment; in the construction step 7), when the semi-cylindrical mold is placed in the pile hole, the bottom of the semi-cylindrical mold abuts against the cage step.

8. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 6, characterized in that: A longitudinally arranged web is provided in the middle of the semi-cylindrical cavity, one side of the web is butted with the straight plate, and the other side of the web is butted with the arc plate; a plurality of transversely arranged arc strips are provided in the semi-cylindrical cavity, the plurality of arc strips are arranged at intervals along the height direction of the semi-cylindrical cavity, and the arc strips are arranged to be bent in the same direction along the bending direction of the arc plate; The arc strip is butted against the inner side wall of the arc plate, two ends of the arc strip are butted against two ends of the straight plate respectively, and the middle part of the arc strip passes through the other side of the web.

9. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 8, characterized in that: The web divides the semi-cylindrical mold into two separated divided cavities, an elastic plate is arranged in the divided cavity, two ends of the top of the elastic plate are respectively fixedly connected to the web and the arc plate, two sides and the bottom of the elastic plate are freely arranged, and the bottom of the elastic plate is located above the bottom plate; The elastic plate divides the segmented cavity into a plurality of elastic cavities arranged at intervals. Along the extension direction of the elastic plate from top to bottom, the elastic plate is arranged obliquely toward the straight plate. The sandbags are filled in the elastic cavities and squeeze the elastic plate away from the web to deform elastically.

10. The one-time pile construction method of variable-section semicircular support occlusal piles at the top of the foundation pit as claimed in claim 9, characterized in that: The elastic plate has an inner side surface facing the web, and a plurality of arc steps are convexly provided on the inner side surface, and the arc steps are arranged to protrude toward the web; the sandbag abuts against the arc steps to squeeze the elastic plate away from the web to elastically deform.

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