CN111962523A - Combined supporting structure of inclined tubular pile and vertical wedge-shaped pile and construction method thereof - Google Patents
Combined supporting structure of inclined tubular pile and vertical wedge-shaped pile and construction method thereof Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 34
- 238000009412 basement excavation Methods 0.000 claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000004568 cement Substances 0.000 claims description 39
- 238000003756 stirring Methods 0.000 claims description 33
- 239000002689 soil Substances 0.000 claims description 29
- 239000002002 slurry Substances 0.000 claims description 19
- 229910000831 Steel Inorganic materials 0.000 claims description 16
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- 238000007667 floating Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 230000002787 reinforcement Effects 0.000 claims description 6
- 239000000498 cooling water Substances 0.000 claims description 4
- 230000009191 jumping Effects 0.000 claims description 4
- 238000005192 partition Methods 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 abstract description 4
- 238000009415 formwork Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 2
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- 239000007788 liquid Substances 0.000 description 1
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Abstract
The invention discloses a combined supporting structure of an inclined tubular pile and a vertical wedge-shaped pile, which comprises a row pile supporting structure formed by alternately arranging tubular piles and wedge-shaped piles; the tubular pile and the wedge-shaped pile are arranged along the inner side of the edge of the foundation pit, and a crown beam is arranged on the pile top of the tubular pile and the wedge-shaped pile; the axis of the wedge-shaped pile is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is sequentially reduced from the pile top to the pile bottom; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined towards the inside of the foundation pit; and the pile top central connecting line of the tubular pile is parallel to or coincided with the pile top central connecting line of the wedge-shaped pile. The invention also discloses a construction method of the combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile. The invention can reduce the displacement of the pile top, increase the excavation depth, reduce the possibility of foundation pit overturning damage, and reduce the design strength of the support pile so as to reduce the manufacturing cost.
Description
Technical Field
The invention relates to a foundation pit supporting structure and a construction method, in particular to a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile and a construction method thereof.
Background
At present, with the advance of the national urbanization process, underground large-area and large-length foundation pits account for more than 80 percent of the total area of the foundation pits in China. But the traditional support mode has great defects and shortcomings: 1. the cantilever foundation pit supporting structure can only be applied to foundation pit engineering with shallow excavation depth and good soil condition; 2. for the inner support supporting structure, although the inner support supporting structure can be applied to a deep foundation pit, the construction is complex, the construction period is long, the environmental pollution is serious, and the construction cost is high. Therefore, the inclined pile supporting structure comes into play, inclined supporting piles are formed by inclining the vertical cantilever supporting piles to a certain angle in the foundation pit, and the inclined supporting piles and the vertical supporting piles are arranged alternately, so that the inclined-straight alternate supporting structure can be formed. Traditional oblique straight alternative fender pile all adopts the tubular pile, in soft soil foundation engineering, the tubular pile atress form is friction foundation pile mostly, and the concrete intensity (C60-C100) of tubular pile body is very high, but the specific surface area (the ratio of unit concrete volume and pile body external surface area) of pile body is less, consequently the effort between tubular pile body outward appearance and soil is less than pile body intensity far away, pile body structural strength can not obtain abundant performance, the very big waste of concrete pipe pile bearing capacity has been caused, unable full play supporting construction's pile body frictional force. The whole supporting capability of the supporting structure is mainly exerted by the tension given by the straight pile to the inclined pile, and the traditional tubular pile cannot fully exert the tension.
Disclosure of Invention
The invention provides a combined supporting structure of an inclined tubular pile and a vertical wedge-shaped pile and a construction method thereof for solving the technical problems in the prior art.
The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile comprises a row pile supporting structure formed by alternately arranging the pipe pile and the wedge-shaped pile; the tubular pile and the wedge-shaped pile are arranged along the inner side of the edge of the foundation pit, and a crown beam is arranged on the pile top of the tubular pile and the wedge-shaped pile; the axis of the wedge-shaped pile is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is sequentially reduced from the pile top to the pile bottom; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined towards the inside of the foundation pit; and the pile top central connecting line of the tubular pile is parallel to or coincided with the pile top central connecting line of the wedge-shaped pile.
Further, the included angle between the axis of the tubular pile and the axis of the wedge-shaped pile is less than or equal to 30 degrees.
Further, the pile bottom depth of the tubular pile or the wedge-shaped pile is 2-2.5 times of the excavation depth of the foundation pit.
Further, the pile diameter of the tubular pile is 300-600 mm; the pile top diameter of the wedge-shaped pile is 600-1200 mm, and the wedge angle of the wedge-shaped pile is 5-15 degrees.
Further, the width direction edge of crown beam surpasss the tubular pile with the pile bolck edge of wedge pile, the height more than or equal to 0.6 times of tubular pile footpath or 0.6 times of the average stake footpath of wedge pile of crown beam.
Further, the width direction edge unilateral of crown beam surpasss the pile bolck edge size of tubular pile and wedge-shaped pile is: 1/2 pile diameter or 1/2 wedge pile average pile diameter.
The invention also provides a construction method of the combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile, which comprises the following steps: prefabricating a tubular pile and a wedge-shaped pile; arranging tubular piles and wedge-shaped piles along the inner side of the edge of the foundation pit on site, and enabling the tubular piles and the wedge-shaped piles to be alternately arranged to form a pile arrangement supporting structure; the axis of the wedge-shaped pile is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is reduced from the pile top to the pile bottom in sequence; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined to the inside of the foundation pit; enabling a pile top central connecting line of the tubular pile and a pile top central connecting line of the wedge-shaped pile to be parallel or coincident, adopting a pile jumping construction method for the tubular pile and the wedge-shaped pile, and pressing a next precast pile at intervals of 1-2 piles; and (4) prefabricating a crown beam on the pile top of the tubular pile and the pile top of the wedge-shaped pile.
Further, the method for laying the wedge-shaped piles in the field comprises the following steps:
step A-1, performing wedge pile hole forming operation on a target foundation to ensure that the hole diameter of the excavated hole is gradually reduced from top to bottom;
step A-2, after hole forming, paving a concrete cushion layer at the hole bottom;
step A-3, after the wedge-shaped pile is lifted and sunk, pouring concrete into the hollow section, and vibrating and compacting while pouring;
step A-4, after pouring, excavating a bearing platform foundation pit, aligning a bolt hole and a grouting hole of a bearing platform cover plate with a fixing bolt and a grouting guide pipe of a wedge-shaped pile top section correspondingly, attaching the bearing platform cover plate to the pile top of the wedge-shaped pile and the side wall of the bearing platform foundation pit, backfilling the bearing platform foundation pit, and filling the edge tightly;
and step A-5, grouting the guide pipe by adopting cement paste until cement paste is spread out from the soil layer on the side of the pile.
Further, setting the length of the wedge-shaped pile to be L, and arranging a cement mixing pile waterproof curtain at the position which is outside the pile top center connecting line of the wedge-shaped pile and is 0.2L away from the pile top center connecting line of the wedge-shaped pile; the construction method of the waterproof curtain of the cement mixing pile comprises the following steps:
b-1, enabling the deep layer stirrer to reach the designated pile position and centering;
b-2, after the cooling water circulation of the deep layer stirrer is normal, starting the deep layer stirrer to enable the deep layer stirrer to stir along the guide frame, cut soil and sink;
step B-3, when the deep layer stirrer sinks to a set depth, stirring cement paste and pouring the cement paste into a collecting hopper;
step B-4, after the deep layer stirrer sinks to the designed depth, starting a cement slurry pump to press cement slurry into the foundation, spraying the cement slurry and rotating and stirring the cement slurry, and simultaneously lifting the deep layer stirrer according to the lifting speed determined by the design;
and step B-5, after the deep layer stirring machine is lifted to the top surface elevation of the designed depth, the deep layer stirring machine is sunk into the soil while rotating and stirring, and the deep layer stirring machine is lifted out of the ground after the design depth.
Further, the method for prefabricating the crown beam on the pile top of the tubular pile and the pile top of the wedge-shaped pile comprises the following steps of:
c-1, excavating the earthwork of the crown beam in a mechanical partition mode, excavating a first layer of earthwork to reach the pile top elevation of the wedge-shaped pile, removing residual soil, then beginning to remove pile head floating slurry to reach the designed elevation, chiseling the concrete on the top surface of the pile core, removing the pile top floating slurry, and continuing to remove the pile head floating slurry until the concrete quality reaches the designed requirement if the pile head concrete strength at the designed elevation does not reach the designed requirement;
c-2, leveling the soil between the piles to the elevation of the bottom of the crown beam, and compacting by tamping;
c-3, manufacturing steel bars according to the cross section reinforcements of the crown beam; the longitudinal bars adopt HRB335 grade or HRB400 grade steel bars, and the stirrups adopt HPB300 grade steel bars; the tie bars are HRB 335-grade steel bars;
c-4, completing concrete pouring and curing; the concrete strength grade is higher than or equal to C25, and the main reinforcement of the row pile is anchored into the crown beam and is more than or equal to 35 times of the diameter of the reinforced pile.
The invention has the advantages and positive effects that: according to the combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile, the tubular pile and the wedge-shaped pile are alternately arranged to form the equal-height combined supporting structure, so that the axis of the wedge-shaped pile is perpendicular to the horizontal plane, and the area of the cross section of the wedge-shaped pile is sequentially reduced from the pile top to the pile bottom; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined to the inside of the foundation pit; the wedge-shaped pile can increase the side friction resistance, so that the axial force can be fully exerted, greater pulling force is given to the tubular pile, the pile top displacement is reduced to a great extent, the ground deformation after the pile is arranged is greatly reduced, the damage to the surrounding environment is avoided, meanwhile, the pile body bending moment can be reduced, the design strength of the pile body is reduced, and the construction cost is reduced; the invention can increase the excavation depth, and because the excavation surface is inclined, and the wedge-shaped pile has high bearing capacity and small settlement, the probability of the foundation pit overturn and damage is greatly reduced, and the safety of the foundation pit engineering can be ensured; the tubular piles and the wedge-shaped piles are alternately arranged to form the equal-height combined supporting structure, so that the design requirement can be met only by utilizing the cantilever pile support in the foundation pit engineering which possibly needs an internal support type support or a pull anchor type support, the design and construction are simpler and more convenient, the materials are saved, and the engineering cost is reduced.
In conclusion, the invention can reduce the displacement of the pile top, increase the excavation depth, reduce the possibility of foundation pit overturning damage, and reduce the design strength of the support pile so as to reduce the construction cost of the foundation pit support engineering.
Drawings
Fig. 1 is a schematic view of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile.
In the figure: 1-a crown beam; 2-foundation pit bottom; 3-the edge of the foundation pit; 4-wedge-shaped piles; 5-pipe pile.
Fig. 2 is a schematic cross-sectional view of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile according to the invention.
In the figure: h1-excavation depth of the foundation pit; h2-wedge pile length; theta-inclination angle of the pipe pile.
Detailed Description
For further understanding of the contents, features and effects of the present invention, the following embodiments are enumerated in conjunction with the accompanying drawings, and the following detailed description is given:
referring to fig. 1 to 2, a combined supporting structure of an inclined tubular pile and a vertical wedge-shaped pile includes a row pile supporting structure formed by tubular piles 5 and wedge-shaped piles 4 which are alternately arranged; the tubular pile 5 and the wedge-shaped pile 4 are arranged along the inner side of the edge 3 of the foundation pit, and the top of the tubular pile 5 and the top of the wedge-shaped pile 4 are provided with crown beams 1; the axis of the wedge-shaped pile 4 is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is gradually reduced from the pile top to the pile bottom; the axis of the tubular pile 5 is inclined to the horizontal plane, and the lower part of the tubular pile is inclined towards the inside of the foundation pit; and the pile top central connecting line of the tubular pile 5 is parallel to or coincided with the pile top central connecting line of the wedge-shaped pile 4. The tubular pile 5 with the pile bolck of wedge pile 4 is located the inboard at foundation ditch border 3, and tubular pile 5 and wedge pile 4 form a whole through 1 connections of crown beam.
The pile top center connecting line of the tubular pile 5 can be positioned at the inner side of the pile top center connecting line of the wedge-shaped pile 4; the pile spacing between adjacent tubular piles 5 and wedge-shaped piles 4 can be 2-4 times of the pile diameter of the tubular pile or 2-4 times of the average pile diameter of the wedge-shaped piles.
The axis of the wedge-shaped pile is a straight line which is perpendicular to the top surface of the wedge-shaped pile and intersects with the center of the top surface of the wedge-shaped pile, and the pile diameter of the wedge-shaped pile is the ratio of 4 times of the area to the perimeter of the cross section which is perpendicular to the axis of the wedge-shaped pile; the area of the cross section of the wedge-shaped pile is sequentially reduced from the pile top to the pile bottom; the corresponding pile diameter is also reduced from the pile top to the pile bottom in sequence.
The inclination angle of the axis of the tubular pile 5 relative to the axis of the wedge-shaped pile 4 can be larger than 0 degree and smaller than or equal to 30.5 degrees, and the angle of an included angle between the axis of the tubular pile and the axis of the wedge-shaped pile is preferably smaller than or equal to 30 degrees. As shown in fig. 2, an included angle between the axis of the pipe pile and the axis of the wedge-shaped pile may be referred to as a pipe pile inclination angle θ, and the pipe pile inclination angle θ may be equal to or less than 30 °. The inclination angle theta of the tubular pile can be preferably 10 degrees, 12 degrees, 15 degrees, 18 degrees, 21 degrees and 24 degrees.
The pile bottom depth of the tubular pile 5 or the wedge-shaped pile 4 can be 2-2.5 times of the excavation depth H of the foundation pit1. Namely, the height of the tubular pile 5 or the pile bottom end of the wedge-shaped pile 4 from the bottom 2 of the foundation pit is 2-2.5 times of the excavation depth H of the foundation pit1。
The pile diameter of the tubular pile can be 300-600 mm; the pile top diameter of the wedge-shaped pile can be 600-1200 mm, and the wedge angle of the wedge-shaped pile can be 5-15 degrees. The wedge angle of the wedge-shaped pile is preferably 7.5 degrees, 9 degrees and 12 degrees.
And the wedge-shaped piles 4 and the tubular piles 5 are provided with crown beams 1. The width of crown beam 1 can be greater than the pile-top pile diameter of tubular pile 5 and wedge-shaped pile 4 connected with it, the width direction edge of crown beam 1 can exceed tubular pile 5 with the pile-top edge of wedge-shaped pile 4, the height of crown beam 1 can be greater than or equal to 0.6 times of the pile diameter of tubular pile 5 or 0.6 times of the average pile diameter of wedge-shaped pile 4.
Further, the dimension of the width direction edge of the crown beam 1 exceeding the pile top edge of the tubular pile 5 and the wedge-shaped pile 4 on one side may be: 1/2 pile diameter of pile 5 or 1/2 wedge pile 4 average diameter.
The length of the wedge-shaped pile can be set to be L, and a cement mixing pile waterproof curtain can be arranged at the position which is outside the pile top center connecting line of the wedge-shaped pile and is 0.2L away from the pile top center connecting line of the wedge-shaped pile.
The invention also provides an embodiment of a construction method of the combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile, which comprises the following steps: prefabricating a tubular pile 5 and a wedge-shaped pile 4; arranging tubular piles 5 and wedge-shaped piles 4 along the inner side of the edge of the foundation pit on site, and enabling the tubular piles 5 and the wedge-shaped piles 4 to be alternately arranged to form a pile arrangement supporting structure; the axis of the wedge-shaped pile 4 is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is reduced from the pile top to the pile bottom in sequence; the axis of the tubular pile 5 is inclined to the horizontal plane, and the lower part of the tubular pile is inclined to the inside of the foundation pit; enabling a pile top center connecting line of the tubular pile 5 and a pile top center connecting line of the wedge-shaped pile 4 to be parallel or coincident, and pressing the tubular pile 5 and the wedge-shaped pile 4 into the next precast pile at intervals of 1-2 piles by adopting a pile jumping construction method; and (3) prefabricating the crown beam 1 on the pile top of the tubular pile 5 and the pile top of the wedge-shaped pile 4. The pile top center connecting line of the tubular pile 5 can be positioned at the inner side of the pile top center connecting line of the wedge-shaped pile 4; the distance between adjacent tubular piles 5 and wedge-shaped piles 4 can be 2-4 times of the pile diameter of the tubular piles or 2-4 times of the average pile diameter of the wedge-shaped piles.
Further, the method of laying the wedge pile 4 in the field may comprise the steps of:
and step A-1, performing hole forming operation on the wedge-shaped pile 4 on the target foundation to ensure that the excavated hole diameter is gradually reduced from top to bottom.
And step A-2, after the hole is formed, paving a concrete cushion layer at the bottom of the hole.
And step A-3, after the wedge-shaped piles 4 are hung and sunk, pouring concrete into the hollow sections, and vibrating and compacting while pouring.
And step A-4, after the pouring is finished, excavating a bearing platform foundation pit, aligning a bolt hole and a grouting hole of a bearing platform cover plate with a fixing bolt and a grouting guide pipe of the pile top section of the wedge-shaped pile 4 correspondingly, attaching the bearing platform cover plate to the pile top of the wedge-shaped pile 4 and the side wall of the bearing platform foundation pit, backfilling the bearing platform foundation pit, and tightly filling the edge.
And step A-5, grouting the guide pipe by adopting cement paste until cement paste is spread out from the soil layer on the side of the pile.
Further, the length of the wedge-shaped pile 4 can be set to be L, and a cement mixing pile waterproof curtain can be arranged on the outer side of the pile top center connecting line of the wedge-shaped pile 4 and 0.2L away from the pile top center connecting line of the wedge-shaped pile 4; the construction method of the waterproof curtain of the cement mixing pile can comprise the following steps:
and step B-1, enabling the deep layer stirrer to reach the designated pile position and centering.
And step B-2, after the cooling water circulation of the deep layer stirrer is normal, starting the deep layer stirrer to enable the deep layer stirrer to stir along the guide frame, cut soil and sink.
And step B-3, when the deep layer stirrer sinks to the set depth, stirring the cement paste and pouring the cement paste into a collecting hopper.
And step B-4, after the deep layer stirring machine sinks to the designed depth, starting a cement slurry pump to press cement slurry into the foundation, spraying the cement slurry while rotating and stirring, and simultaneously lifting the deep layer stirring machine according to the lifting speed determined by design.
And step B-5, after the deep layer stirring machine is lifted to the top surface elevation of the designed depth, the deep layer stirring machine is sunk into the soil while rotating and stirring, and the deep layer stirring machine is lifted out of the ground after the design depth.
Further, the method of prefabricating the crown beam 1 on the pile top of the pipe pile 5 and the pile top of the wedge-shaped pile 4 may include the steps of:
and C-1, excavating the earthwork of the crown beam 1 by mechanical partition, excavating a first layer of earthwork to the pile top elevation of the wedge-shaped pile 4, removing residual soil, then beginning to remove pile head laitance to the designed elevation, chiseling the concrete on the top surface of the pile core, removing the pile top laitance, and continuing to remove the pile head laitance until the concrete quality reaches the designed requirement if the pile head concrete strength at the designed elevation does not reach the designed requirement.
And C-2, leveling the soil between the piles to the elevation of the bottom of the crown beam 1, and compacting by tamping.
And C-3, manufacturing the steel bars according to the reinforcing bars on the section of the crown beam 1. The longitudinal bars adopt HRB335 grade or HRB400 grade steel bars, and the stirrups adopt HPB300 grade steel bars; the tie bars are HRB335 grade steel bars.
C-4, completing concrete pouring and curing; the concrete strength grade is higher than or equal to C25, and the row pile main reinforcement is anchored into the crown beam 1 and is larger than or equal to 35 times of the diameter of the reinforced pile.
The structure, construction and operation of the present invention will be further described in the following with reference to a preferred embodiment thereof:
referring to fig. 1, the combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile comprises a plurality of tubular piles 5 and a plurality of wedge-shaped piles 4, wherein the tubular piles 5 and the wedge-shaped piles 4 are alternately arranged to form an isometric combined supporting structure; the axis of the wedge-shaped pile 4 is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is gradually reduced from the pile top to the pile bottom; the axis of the tubular pile 5 is inclined to the horizontal plane, and the lower part of the tubular pile is inclined towards the inside of the foundation pit; the pile top center connecting line of the tubular pile 5 is parallel to the pile top center connecting line of the wedge-shaped pile 4, the wedge-shaped pile 4 is arranged along the inner side of the foundation pit edge 3, and the tubular pile 5 is positioned on the inner side of the pile top center connecting line of the wedge-shaped pile 4; and the top of the tubular pile 5 and the top of the wedge-shaped pile 4 are provided with crown beams 1.
The wedge-shaped piles 4 are vertical supporting piles, the tubular piles 5 are inward-inclined supporting piles, and all the wedge-shaped piles and all the tubular piles are connected into a whole through the crown beam 1. And a waterproof curtain is arranged on the outer side of the central connecting line of the pile tops of the wedge-shaped piles 4.
The basic principle of the invention is as follows:
the tubular piles 5 and the wedge-shaped piles 4 are alternately arranged to form a combined supporting structure, when the vertical supporting piles are the wedge-shaped piles 4, and the inward-inclined supporting piles are the tubular piles 5, the combined supporting structure formed by the tubular piles 5 and the wedge-shaped piles 4 in an alternate arrangement mode is also called an oblique-straight alternate supporting structure, and the tubular piles 5 and the wedge-shaped piles 4 are connected through the pile top crown beams 1 to form a whole and are stressed together. Wherein the tubular pile 5 is pressed and the wedge-shaped pile 4 is pulled. Through the crown beam 1, the wedge-shaped pile 4 provides self axial force to the tubular pile 5, and the tubular pile 5 can be given a downward pulling force, and the pulling force is related to the side friction force of the wedge-shaped pile 4.
The tension can effectively reduce the deformation of the pile body, thereby reducing the deformation of the foundation pit soil body, protecting the surrounding buildings, and increasing the excavation depth H of the foundation pit1And the stability of the foundation pit is enhanced. When the vertical support pile adopts the wedge-shaped pile 4 to support the foundation pit, the area of the cross section of the pile body is sequentially reduced from the pile top to the pile bottom, so that the contact area between the wedge-shaped pile and a soil body, particularly a soil layer with a better bottom is increased, the side friction resistance can be effectively increased, the tension of the wedge-shaped pile is increased, and the foundation pit displacement is further controlled.
Compared with other supporting structures, the invention can effectively exert the pulling force of the wedge-shaped pile 4, thereby shortening the length H of the wedge-shaped pile2Increase the pile spacing of the supporting piles and reduce the supportPile diameter of the pile. Before construction, the optimal inclination angle of the tubular pile is determined according to site conditions and calculation analysis, and the pile length and the pile body strength of the wedge-shaped pile 4 and the tubular pile 5 are designed. The invention is suitable for a cantilever pile supporting mode. The invention recommends that the inclination angle of the tubular pile 5 is more than 0 degree and less than or equal to 30.5 degrees; the pile bottom depth of the wedge-shaped piles 4 and the tubular piles 5 is 2-2.5 times of the excavation depth H of the foundation pit1(ii) a The pile spacing between the adjacent wedge-shaped piles 4 and the tubular pile 5 is 2-2.5 times of the pile diameter. The pile diameter of the tubular pile 5 is 300-600 mm, the pile diameter of the pile head of the wedge-shaped pile 4 is about 600-1200 mm, and the pile diameter of the pile bottom of the wedge-shaped pile 4 is 300-600 mm.
A construction method of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile comprises the following steps:
prefabricating a pipe pile 5 and a wedge-shaped pile 4 with equal length; laying the tubular piles 5 and the wedge-shaped piles 4 on site, and alternately arranging the tubular piles 5 and the wedge-shaped piles 4; the axis of the wedge-shaped pile 4 is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is reduced from the pile top to the pile bottom in sequence; the axis of the tubular pile 5 is inclined to the horizontal plane, and the lower part of the tubular pile is inclined to the inside of the foundation pit; the pile top center connecting line of the tubular pile 5 is parallel to the pile top center connecting line of the wedge-shaped pile 4, the wedge-shaped pile 4 is arranged along the inner side of the foundation pit edge 3, and the tubular pile 5 is positioned on the inner side of the pile top center connecting line of the wedge-shaped pile 4; the tubular pile 5 and the wedge-shaped pile 4 are both driven into the next precast pile at intervals of 1-2 piles by adopting a pile jumping construction method; and (3) prefabricating the crown beam 1 on the pile top of the tubular pile 5 and the pile top of the wedge-shaped pile 4.
The construction method of the wedge-shaped pile 4 comprises the following steps:
1) and (4) forming a hole on the target foundation by the wedge-shaped pile 4, and digging the hole with the gradually reduced hole diameter from top to bottom.
2) After the hole is formed, a concrete cushion is paved at the pile end.
3) After the wedge-shaped piles 4 are hung, sunk and hoisted, concrete is poured on the hollow section, and the hollow section is compacted by vibration while pouring.
4) Assembling a bearing platform: after the pouring is finished, a bearing platform foundation pit is excavated, bolt holes and grouting holes of a bearing platform cover plate are aligned to fixing bolts and grouting guide pipes of the pile top section, the bearing platform cover plate and the side wall are tightly attached to the wedge-shaped piles 4, the bearing platform foundation pit is backfilled, and the edge is tightly filled.
5) Grouting a guide pipe: and after the installation is finished, grouting the guide pipe by using cement paste until cement paste overflows from the soil layer on the side of the pile.
When the center distance of the piles is less than or equal to 4 times of the pile diameter, the piles are dense and are symmetrically driven from the middle to two sides, so that the soil body is extruded from the periphery to two sides during driving, and the construction quality is ensured. When the number of piles is large, the piles can be driven in sections. When the center distance of the piles is more than or equal to 4 times of the side length or the pile diameter, the piles are sparse, and the driving sequence or the driving mode that one side is driven in a single direction can be adopted.
Setting the length of the wedge-shaped pile 4 as L, and arranging a cement mixing pile waterproof curtain at the position which is outside the pile top center connecting line of the wedge-shaped pile 4 and is 0.2L away from the pile top center connecting line of the wedge-shaped pile 4; the pile bottom elevation of the stirring pile of the waterproof curtain is the same as the pile bottom elevation of the wedge-shaped pile 4.
The construction method of the waterproof curtain of the cement mixing pile comprises the following steps:
1) positioning: and the deep mixer reaches the designated pile position and is centered.
2) Pre-stirring and sinking: after the cooling water circulation of the deep layer stirrer is normal, starting a stirrer motor, and loosening a sling of the stirrer to enable the stirrer to stir along the guide frame, cut soil and sink.
3) Preparing cement paste: when the deep layer stirrer sinks to a certain depth, the cement paste is stirred according to the mixing ratio determined by the design, and the cement paste is poured into the collecting hopper before grouting.
4) Lifting, spraying and stirring: after the deep mixer sinks to the design degree of depth, open the mortar pump and impress grout into the ground, and spout thick liquid, rotatory simultaneously, strictly according to the lifting speed who designs and confirm promotes deep mixer.
5) Repeating the upper stirring and the lower stirring: when the deep-layer stirring machine is lifted to the top surface elevation of the designed depth, the cement slurry in the collecting hopper is just emptied. For the time soft soil and grout stirring, can be once more with the mixer rotatory while sinking in soil, promote the mixer out of ground again after the design consolidates the degree of depth.
6) Cleaning: and (4) cleaning residual cement paste in all pipelines, and cleaning soft soil adhered to the stirring head.
7) And (3) shifting: and moving the deep layer stirring machine to the next pile position, and repeating the steps.
And a crown beam 1 is arranged above the wedge-shaped piles 4 and the tubular piles 5. The width of the crown beam 1 is recommended to be larger than the pile diameter of a pipe pile 5 or the pile diameter of a wedge-shaped pile 4 connected with the crown beam, and the height of the crown beam 1 can be larger than or equal to 0.6 time of the pile diameter of the pipe pile 5 or 0.6 time of the average pile diameter of the wedge-shaped pile 4. The two sides of the crown beam 1 in the width direction are respectively expanded to obtain the pile diameter of 1/2 tubular piles 5 or the average pile diameter of 1/2 wedge-shaped piles 4.
The construction method of the crown beam 1 comprises the following steps:
1) the method comprises the steps that mechanical partition excavation is adopted for the earthwork of the crown beam 1, a first layer of earthwork is excavated to the designed pile top elevation of the supporting pile, pile head floating slurry is broken to the designed elevation after residual soil is removed, the concrete on the top surface of the pile core needs to be chiseled, and pile top floating slag is removed, if the strength of the pile head concrete at the designed elevation does not meet the design requirement, the pile head concrete needs to be broken continuously until the concrete quality meets the design requirement, and the crown beam 1 concrete is poured and formed together when the section with the elevation is insufficient.
2) And (5) manually leveling the soil between the piles to the elevation of the bottom of the crown beam 1, and compacting by tamping.
3) And (4) after the pile head is broken, manufacturing the steel bars according to the reinforcing bars on the section of the crown beam 1. And the blanking and binding errors of the reinforcing steel bars are ensured to meet the requirements of design and construction specifications.
4) And checking the elevation of the crown beam 1 and installing a template. The formwork support needs to ensure the stability and firmness of the formwork to prevent the deformation of the formwork when concrete is poured, and the section size of the formwork is manufactured according to the section of the crown beam 1.
5) And finishing the reinforcing steel bar engineering. The longitudinal bars are preferably HRB335 grade or HRB400 grade steel bars, and the stirrups and the tie bars are HPB300 grade and HRB335 grade steel bars.
6) And finishing concrete pouring and maintenance. The concrete strength grade should not be lower than C25, and the row pile main reinforcement anchored into the crown beam 1 should not be less than 35d (d is the diameter of the steel bar pile).
The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.
Claims (10)
1. A combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile is characterized by comprising a row pile supporting structure formed by alternately arranging pipe piles and wedge-shaped piles; the tubular pile and the wedge-shaped pile are arranged along the inner side of the edge of the foundation pit, and a crown beam is arranged on the pile top of the tubular pile and the wedge-shaped pile; the axis of the wedge-shaped pile is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is sequentially reduced from the pile top to the pile bottom; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined towards the inside of the foundation pit; and the pile top central connecting line of the tubular pile is parallel to or coincided with the pile top central connecting line of the wedge-shaped pile.
2. The combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile according to claim 1, wherein an included angle between an axis of the pipe pile and an axis of the wedge-shaped pile is not more than 30 degrees.
3. The combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile according to claim 1, wherein the depth of the pile bottom of the tubular pile or the wedge-shaped pile is 2-2.5 times of the excavation depth of a foundation pit.
4. The combined supporting structure of the inclined tubular pile and the vertical wedge-shaped pile according to claim 1, wherein the diameter of the tubular pile is 300-600 mm; the pile top diameter of the wedge-shaped pile is 600-1200 mm, and the wedge angle of the wedge-shaped pile is 5-15 degrees.
5. The combined supporting structure of an inclined tubular pile and a vertical wedge-shaped pile according to claim 1, wherein the width direction edge of the crown beam exceeds the tubular pile and the pile top edge of the wedge-shaped pile, and the height of the crown beam is greater than or equal to 0.6 time of the pile diameter of the tubular pile or 0.6 time of the average pile diameter of the wedge-shaped pile.
6. The combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile according to claim 5, wherein the dimension of the width direction edge of the crown beam beyond the pile top edges of the pipe pile and the wedge-shaped pile on one side is as follows: 1/2 pile diameter or 1/2 wedge pile average pile diameter.
7. A construction method of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile is characterized by comprising the following steps: prefabricating a tubular pile and a wedge-shaped pile; arranging tubular piles and wedge-shaped piles along the inner side of the edge of the foundation pit on site, and enabling the tubular piles and the wedge-shaped piles to be alternately arranged to form a pile arrangement supporting structure; the axis of the wedge-shaped pile is vertical to the horizontal plane, and the area of the cross section of the wedge-shaped pile is reduced from the pile top to the pile bottom in sequence; the axis of the tubular pile is inclined to the horizontal plane, and the lower part of the tubular pile is inclined to the inside of the foundation pit; enabling a pile top central connecting line of the tubular pile and a pile top central connecting line of the wedge-shaped pile to be parallel or coincident, adopting a pile jumping construction method for the tubular pile and the wedge-shaped pile, and pressing a next precast pile at intervals of 1-2 piles; and (4) prefabricating a crown beam on the pile top of the tubular pile and the pile top of the wedge-shaped pile.
8. The construction method of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile according to claim 7, wherein the method for laying the wedge-shaped pile in the field comprises the following steps:
step A-1, performing wedge pile hole forming operation on a target foundation to ensure that the hole diameter of the excavated hole is gradually reduced from top to bottom;
step A-2, after hole forming, paving a concrete cushion layer at the hole bottom;
step A-3, after the wedge-shaped pile is lifted and sunk, pouring concrete into the hollow section, and vibrating and compacting while pouring;
step A-4, after pouring, excavating a bearing platform foundation pit, aligning a bolt hole and a grouting hole of a bearing platform cover plate with a fixing bolt and a grouting guide pipe of a wedge-shaped pile top section correspondingly, attaching the bearing platform cover plate to the pile top of the wedge-shaped pile and the side wall of the bearing platform foundation pit, backfilling the bearing platform foundation pit, and filling the edge tightly;
and step A-5, grouting the guide pipe by adopting cement paste until cement paste is spread out from the soil layer on the side of the pile.
9. The construction method of a combined supporting structure of an inclined tubular pile and a vertical wedge-shaped pile according to claim 7, characterized in that the length of the wedge-shaped pile is set to be L, and a cement mixing pile waterproof curtain is arranged at the position which is outside the center connecting line of the pile tops of the wedge-shaped piles and is 0.2L away from the center connecting line of the pile tops of the wedge-shaped piles; the construction method of the waterproof curtain of the cement mixing pile comprises the following steps:
b-1, enabling the deep layer stirrer to reach the designated pile position and centering;
b-2, after the cooling water circulation of the deep layer stirrer is normal, starting the deep layer stirrer to enable the deep layer stirrer to stir along the guide frame, cut soil and sink;
step B-3, when the deep layer stirrer sinks to a set depth, stirring cement paste and pouring the cement paste into a collecting hopper;
step B-4, after the deep layer stirrer sinks to the designed depth, starting a cement slurry pump to press cement slurry into the foundation, spraying the cement slurry and rotating and stirring the cement slurry, and simultaneously lifting the deep layer stirrer according to the lifting speed determined by the design;
and step B-5, after the deep layer stirring machine is lifted to the top surface elevation of the designed depth, the deep layer stirring machine is sunk into the soil while rotating and stirring, and the deep layer stirring machine is lifted out of the ground after the design depth.
10. The construction method of a combined supporting structure of an inclined pipe pile and a vertical wedge-shaped pile according to claim 7, wherein the method of prefabricating a crown beam on the pile top of the pipe pile and the pile top of the wedge-shaped pile comprises the steps of:
c-1, excavating the earthwork of the crown beam in a mechanical partition mode, excavating a first layer of earthwork to reach the pile top elevation of the wedge-shaped pile, removing residual soil, then beginning to remove pile head floating slurry to reach the designed elevation, chiseling the concrete on the top surface of the pile core, removing the pile top floating slurry, and continuing to remove the pile head floating slurry until the concrete quality reaches the designed requirement if the pile head concrete strength at the designed elevation does not reach the designed requirement;
c-2, leveling the soil between the piles to the elevation of the bottom of the crown beam, and compacting by tamping;
c-3, manufacturing steel bars according to the cross section reinforcements of the crown beam; the longitudinal bars adopt HRB335 grade or HRB400 grade steel bars, and the stirrups adopt HPB300 grade steel bars; the tie bars are HRB 335-grade steel bars;
c-4, completing concrete pouring and curing; the concrete strength grade is higher than or equal to C25, and the main reinforcement of the row pile is anchored into the crown beam and is more than or equal to 35 times of the diameter of the reinforced pile.
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