CN117449280A - Composite foundation and construction method - Google Patents
Composite foundation and construction method Download PDFInfo
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- CN117449280A CN117449280A CN202311186059.XA CN202311186059A CN117449280A CN 117449280 A CN117449280 A CN 117449280A CN 202311186059 A CN202311186059 A CN 202311186059A CN 117449280 A CN117449280 A CN 117449280A
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- 238000010276 construction Methods 0.000 title claims abstract description 60
- 239000002131 composite material Substances 0.000 title claims abstract description 52
- 239000002689 soil Substances 0.000 claims abstract description 101
- 239000004567 concrete Substances 0.000 claims abstract description 44
- 238000011049 filling Methods 0.000 claims abstract description 21
- 239000004568 cement Substances 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 21
- 238000005056 compaction Methods 0.000 claims description 15
- 230000035515 penetration Effects 0.000 claims description 11
- 230000002457 bidirectional effect Effects 0.000 claims description 7
- 230000000149 penetrating effect Effects 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 2
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- 239000000463 material Substances 0.000 description 12
- 230000003014 reinforcing effect Effects 0.000 description 10
- 239000004575 stone Substances 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000007789 sealing Methods 0.000 description 5
- 239000000945 filler Substances 0.000 description 4
- 239000011178 precast concrete Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 239000011449 brick Substances 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/223—Details of top sections of foundation piles
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
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- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Agronomy & Crop Science (AREA)
- Environmental & Geological Engineering (AREA)
- Soil Sciences (AREA)
- Piles And Underground Anchors (AREA)
Abstract
The invention discloses a composite foundation and a construction method, which relate to the technical field of foundation treatment construction and comprise the following steps: comprising the following steps: the pile holes and pile bodies are arranged on the foundation, and the pile holes are formed by column hammer impact; the pile body is a bonding strength pile which is formed by filling dry and hard concrete in a pile hole and tamping by using a column hammer, and preferably, the pile body further comprises a pile cap, a gravel layer and a cushion layer, wherein the pile cap is fixedly connected to the top of the pile body, the gravel layer is paved between the pile caps, the cushion layer is paved and compacted on the gravel layer and the top of the pile cap, the strength and the rigidity of a composite foundation are improved, the pile body can be suitable for loose foundation soil, the composite foundation is effectively sealed, and the pile body and the foundation soil are prevented from expanding upwards.
Description
Technical Field
The invention relates to the technical field of foundation treatment construction, in particular to a composite foundation and a construction method.
Background
The foundation (namely, soil and earth) is naturally formed, and the requirements of the building on the strength of the foundation (the foundation is unstable as a result of the unsatisfied requirement on the strength of the foundation, so that the building collapses) and the rigidity (the foundation is deformed greatly as a result of the unsatisfied requirement on the rigidity of the foundation, so that the building subsides and cracks) are often not met, so that the foundation needs to be treated. The composite foundation consists of a cushion layer, a reinforcement (pile) and foundation soil (see figure 1), the foundation is reinforced by the reinforcement (pile), and the pile and the soil act together through the cushion layer to meet the requirements of the building on the strength and the rigidity of the foundation. In order to improve the strength and the rigidity of the composite foundation to the maximum extent, the strength and the rigidity of soil are improved, and the strength and the rigidity of piles are improved.
Piles in the composite foundation are divided into discrete material piles and cohesive strength piles according to pile body materials, wherein the discrete material piles mainly comprise vibroflotation gravel piles, pipe sinking gravel piles, lime soil (soil) compaction piles, column hammer impact expansion piles and the like, and the cohesive strength piles mainly comprise cement soil layer stirring piles, jet grouting piles, rammed cement brick piles, CFG piles and the like.
The discrete material pile is formed by extruding foundation soil to form holes by using methods of sinking pipe, explosion expansion, impact, vibration punching, tamping and the like, so that soil in the pile holes is forced to be extruded transversely and axially, soil around the pile is encrypted, and the strength and rigidity of the foundation soil are improved. But the pile body strength and rigidity of the discrete material pile are lower, the load is transmitted mainly by virtue of the constraint of the soil around the pile, the load is difficult to be transmitted to a deeper soil layer, the strength and rigidity of the reinforced composite foundation are not improved greatly, and the application range is limited.
The pile body with the bonding strength pile has higher strength and rigidity, can exert the side friction resistance of the pile in full pile length, and simultaneously transmits the load to a deeper soil layer, so the strength and rigidity can be greatly improved by adopting the bonding strength pile composite foundation to strengthen the foundation. However, most of the construction of piles with bonding strength adopts a drilling machine to form holes, has no extrusion and encryption effects on original foundation soil, and is not suitable for (at least cannot be directly applied to) loose foundation soil (such as artificial filling soil, construction waste filling soil and the like).
Disclosure of Invention
The invention aims to provide a composite foundation and a construction method, which are used for solving the problems in the prior art, improving the strength and rigidity of the composite foundation, being applicable to loose foundation soil and improving the applicability.
In order to achieve the above object, the present invention provides the following solutions:
the invention provides a composite foundation, comprising: the pile comprises a plurality of pile holes and a plurality of pile bodies, wherein each pile hole is arranged on a foundation, and the pile holes are formed by column hammer impact; the pile body is a bonding strength pile which is formed by filling dry and hard concrete in a pile hole and tamping by using the column hammer, and preferably further comprises a pile cap, a gravel layer and a cushion layer, wherein the pile cap is fixedly connected to the top of the pile body, the gravel layer is paved between the pile caps, and the cushion layer is paved and compacted on the gravel layer and the top of the pile cap.
Preferably, the pile body comprises a back cover and a pile body, wherein the back cover is fixedly connected with the bottom end of the pile body, and the diameter of the back cover is larger than that of the pile body.
Preferably, a plurality of annular protrusions are arranged on the outer side wall of the pile body in the depth direction.
Preferably, the pile cap comprises a cake-shaped concrete prefabricated member and a plurality of L-shaped reinforcing bars, one end of each L-shaped reinforcing bar is buried and fixed in the cake-shaped concrete prefabricated member, the other end of each L-shaped reinforcing bar is fixedly connected to the top end of the pile body, and the diameter of each cake-shaped concrete prefabricated member is larger than that of the pile body.
Preferably, the column hammer comprises a hammer body and a hammer head, wherein the hammer head can be detachably connected to the bottom of the hammer body, and the hammer head is a conical hammer head or a flat bottom hammer head.
Preferably, the thickness of the crushed stone layer is the same as the thickness of the pie-shaped concrete prefabricated member.
Preferably, the cushion layer comprises a cement soil layer and a bidirectional geogrid, wherein the bidirectional geogrid is built in the cement soil layer.
The invention also provides a construction method of the composite foundation, which comprises the following steps:
striking the foundation with the column hammer until a designed hole depth is formed into the pile hole;
casting the dry and hard concrete into the pile hole and hammering the dry and hard concrete by using the column hammer to form the pile body;
preferably, the pile body construction method further comprises driving a pile cap at the top of the pile body after pile body construction is completed; paving a gravel layer between the pile caps; and constructing cushion layers on the pile caps and the gravel layer.
Preferably, the pile body construction includes a back cover construction and a pile body construction, wherein the back cover construction is to fill the pile hole with the dry hard concrete and hammer the pile hammer, and form a back cover until the sum of three penetration is less than 9cm, and further perform the pile body construction on the top of the back cover, that is, repeat the filling-tamping, and fill the pile hole with the dry hard concrete 0.2m each time 3 ～0.3m 3 After each filling, the filling can be continued to be tamped upwards until the pile body is completed until the sum of the last three penetrating degrees is less than or equal to 9cm.
Preferably, the construction sequence of each pile body is pile-by-pile construction from the middle to the periphery.
Compared with the prior art, the invention has the following technical effects:
the invention provides a composite foundation and a construction method.A pile periphery and soil at a pile bottom are forced to be compacted in the process of forming a pile hole by a column hammer impacting the foundation, and foundation soil is compacted for the first time; in the pile forming process, the pile body is extruded outwards again to the periphery, foundation soil is extruded for the second time, the strength and rigidity of the foundation soil are improved through twice extrusion of the foundation soil, meanwhile, the pile body is formed by hammering dry hard concrete, the strength and rigidity are higher, the strength and rigidity of the reinforced composite foundation are improved to the greatest extent, and the pile can be directly applied to loose foundation soil;
further can carry out effectual closure to foundation soil through setting up pile cap, gravel layer and bed course, prevent pile body, foundation soil upward expansion.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of a composite foundation according to the present invention;
FIG. 2 is a flow chart of a construction method of a composite foundation provided by the invention;
FIG. 3 is a specific step diagram of pile forming process in the construction method of the composite foundation provided by the invention;
fig. 4 is a schematic structural view of a column hammer used in the construction method of the composite foundation according to the present invention;
FIG. 5 is a schematic view of pile body construction in the construction method of composite foundation according to the present invention;
FIG. 6 is a schematic view of pile body construction in the construction method of composite foundation according to the present invention;
FIG. 7 is a front view of a pile cap in the construction method of the composite foundation provided by the invention;
FIG. 8 is a top view of FIG. 7;
fig. 9 is a schematic structural view of the composite foundation according to the present invention after pile cap construction is completed;
FIG. 10 is a schematic view of the construction of a gravel layer in the construction method of a composite foundation according to the present invention;
FIG. 11 is a plan view of the composite foundation according to the present invention after the construction of the crushed stone layer is completed;
FIG. 12 is a top view of a bi-directional geogrid in a bedding layer in a method of constructing a composite foundation according to the present invention;
FIG. 13 is an elevation view of a mat in the method of constructing a composite foundation according to the present invention;
FIG. 14 is a plan view of the construction border and artificial fill area positions in embodiment three;
FIG. 15 is a cross-sectional view of a building, natural foundation soil, and artificial fill in accordance with the third embodiment;
FIG. 16 is a prior art processing scheme in embodiment three;
FIG. 17 is a schematic diagram of a construction method of a composite foundation according to a third embodiment of the present invention;
in the figure: 1-foundation; 2-cushion layer; 21-a bi-directional geogrid; 22-a cement layer; 3-a crushed stone layer; 4-pile caps; 41-L-shaped steel bars; 42-a pie-shaped concrete preform; 5-pile body; 51-pile body; 52-sealing the bottom; 53-annular projection; 6-foundation soil; 61-compacted foundation soil; 7-hammer body; 71-a conical hammer head; 72-flat bottom hammer; 8-pile holes; 9-dry hard concrete.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a composite foundation and a construction method thereof, which are used for solving the problems in the prior art, improving the strength and rigidity of the composite foundation, being applicable to loose foundation soil, effectively sealing the composite foundation and preventing pile bodies and foundation soil from expanding upwards.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
The present embodiment provides a composite foundation, as shown in fig. 1, including: the pile comprises a plurality of pile holes 8, a plurality of pile bodies 5, pile caps 4, a gravel layer 3 and a cushion layer 2, wherein the pile holes 8 are arranged on a foundation, and the pile holes 8 are formed by column hammer impact; the pile body 5 is formed by filling dry and hard concrete 9 in a pile hole 8 and tamping by using a column hammer; the pile cap 4 is fixedly connected to the top of the pile body 5; the gravel layer 3 is paved between the pile caps 4; the cushion layer 2 is arranged at the tops of the gravel layer 3 and the pile cap, and soil around the pile and at the bottom of the pile is forced to be compacted in the process that the pile hammer impacts the foundation to form a pile hole 8, so that foundation soil 6 is compacted for the first time; in the piling process, the pile body 51 is extruded outwards again around, foundation soil 6 is compacted for the second time, compacted foundation soil 61 is formed around the pile body through twice compaction of the foundation soil 6, strength and rigidity of the foundation soil 6 are improved, meanwhile, the pile body 51 is formed by hammering hard concrete 9, strength and rigidity are high, the reinforced composite foundation strength and rigidity are improved to the greatest extent, the pile can be directly applied to loose foundation soil 6, in addition, the cushion layer 2 can be effectively sealed, and the pile body 5 and the foundation soil 6 are prevented from expanding upwards.
In a preferred scheme of the embodiment, the pile body 5 comprises a bottom cover 52 and a pile body 51, the bottom cover 52 is fixedly connected with the bottom end of the pile body 51, the diameter of the bottom cover 52 is larger than that of the pile body 51, the bottom of the pile hole 8 is rammed and expanded, the foundation soil 6 around the bottom cover 52 needs to be compacted in the forming process, and a manual bearing layer with good integrity and deformation resistance is formed, so that the bearing capacity of the composite foundation is greatly improved. Meanwhile, the bottom sealing 52 is formed by filling the dry and hard concrete 9 at the bottom of the pile hole 8 and hammering the dry and hard concrete by using a column hammer, the dry and hard concrete can fully utilize underground water to carry out penetration hardening cement, the drainage consolidation effect around the pile body 5 is achieved, the construction period requirement of a concrete consolidation period is not needed, the water is saved, the construction work efficiency is improved, and the foundation treatment engineering which has higher bearing capacity but not large thickness of an upper soil layer and larger thickness of a lower relatively soft soil layer and cannot meet the design requirement can be widely applied.
In a preferred scheme of this embodiment, be provided with a plurality of annular protruding 53 on the lateral wall of pile body 51, this annular protruding 53 is crowded closely to the soil of pile body 51 week, and simultaneously, annular protruding 53 has greatly increased the side friction of stake, is favorable to increasing the rigidity of stake.
In a preferred scheme of this embodiment, pile cap 4 includes cake-shaped precast concrete 42 and a plurality of L-shaped reinforcing bars 41, L-shaped reinforcing bars 41 one end is buried in and fixed in cake-shaped precast concrete 42, the other end is used for fixed connection in the top of pile body 51, cake-shaped precast concrete 42's diameter is greater than the diameter of pile body 51, cake-shaped precast concrete 42 thickness 15cm, diameter is generally 2 times of pile body 51 diameter, the material is concrete, intensity level C30, built-in 4L-shaped reinforcing bars 41 of symmetrical arrangement, diameter 22mm, L-shaped reinforcing bars 41's long limit is 50cm, short side length is 30cm, long limit reinforcing bars part exposes, the tip of exposing reinforcing bars makes the toper in order to conveniently drive into the stake, if pile cap 4 is difficult to drive into pile body 5, can use the electric drill, the aperture is generally 20mm, slightly less than the reinforcing bars diameter, then drive into pile cap 4. The pile cap 4 increases the cross-sectional area of the pile, and can effectively prevent the pile from penetrating into the cushion layer 2 at the upper part of the pile under the action of the expansion force.
In a preferred version of this embodiment, the thickness of the crushed stone layer 3 is the same as the thickness of the pie-shaped concrete preform 42, and the effect of the crushed stone layer 3 is to dissipate the pore water pressure in the foundation soil 6 after piling. The soil often contains water, if the soil is compacted, the water is discharged, otherwise, the compaction is difficult. For example, the wet clothes are packed in the plastic bag, the plastic bag is sealed and squeezed, the wet clothes are difficult to compact under the action of water, if the plastic bag is provided with a plurality of small holes, the water can be discharged through the small holes in the process of squeezing the plastic bag by external force, and the clothes can be compact at the moment. Similarly, in the pile forming process, the foundation soil 6 is extruded by an external force, after the foundation soil 6 is extruded, water in the foundation soil 6 is accumulated, and if a drainage channel is not provided, the foundation soil 6 is difficult to compact. The crushed stone layer 3 serves as a drainage channel.
In a preferred embodiment of the present invention, the mat layer 2 includes a soil cement layer 22 and a bi-directional geogrid 21, the bi-directional geogrid 21 is built in the soil cement layer 22, the common mat layer 2 is modified into a reinforced soil cement layer 22 mat layer 2 in the present invention, the mat layer 2 is made of a layer of bi-directional geogrid 21 and a soil cement layer 22, wherein the bi-directional geogrid 21 is built in the soil cement layer 22, and the tensile strength of the bi-directional geogrid 21 is not less than 50kN/m. The cement soil layer 22 is formed by mixing cement and soil in a volume ratio of 3:7, and is formed by rolling, wherein the compaction coefficient is not lower than 0.92, and the thickness of the cushion layer 2 is 500mm. The bi-directional geogrid 21 has the properties of high tensile strength and low elongation, and the cement soil layer 22 also has higher cohesiveness than the common gravel cushion layer 2. The strength and the integrity of the cushion layer 2 can be greatly improved, the double-rammed dense dry hard concrete 9-pile composite foundation can be effectively sealed, and the pile body 5 and the foundation soil 6 are prevented from expanding upwards.
Example two
The present embodiment also provides a construction method of the composite foundation according to embodiment one, as shown in fig. 2 to 15, comprising the following steps:
(1) And (3) preparation of construction: leveling the site, positioning a ramming machine in place, and positioning the positions of the pile holes 8 according to the drawing.
(2) Adopting a conical heavy column hammer to impact the hole until the depth of the designed hole is reached; and (3) adopting a heavy column hammer (usually 3.5t column hammer) (t is unit ton) to impact and form a hole, namely, the hole is formed by means of gravity impact of the column hammer, the falling distance of the column hammer has no specific requirement, and the hole can be formed. In order to improve the hole forming efficiency, the cylindrical hammer head is replaced by a conical hammer head 71, the hammer head and the hammer body 7 are in threaded connection, and a diamond cutting edge angle can be arranged at the end part of the conical hammer head 71, so that the hole forming is facilitated in the construction waste filling of bricks, tiles and the like; in the pore-forming process, the soil around the pile and at the bottom of the pile is forced to be compacted, which is also the first compaction of foundation soil 6 in the invention; the pile hammer repeatedly impacts the hole, the pile bottom reaches the preset design depth, the pile hammer head is replaced by a flat bottom hammer head 72, and the flat bottom hammer head 72 can better level the pile bottom and compact the pile body 51, and the hammer head and the hammer body 7 are connected in a threaded mode.
(3) Pile body 51 construction: the column hammer is lifted out of the pile hole 8, the material is thrown into the pile hole, the material is dry and hard concrete 9 in a loose state, and the strength grade of the concrete is commonly used as C25 and C30 according to the design requirement. The dry and hard concrete 9 is characterized in that the cement or mortar content is low, the cement or mortar is clenched into clusters, the clusters are landed into flowers (scattered), and the concrete is formed by strong vibration compaction during construction. Is commonly used for highway pavement, damming and the like, and is also used for pile bottom enlarging or sealing 52, but the whole pile body 51 is rarely made of dry and hard concrete 9.
The first filler requires the back cover 52, so the filler amount is slightly larger, 0.5m 3 If the sum of the three penetration degrees is smaller than 9cm, the success of the back cover 52 is indicated, and the next construction of the pile body 51 is carried out. If the sum of penetration of the last three shots is less than 9cm after a plurality of hammering and there is no sign of convergence, the filler needs to be continued in an amount of 0.5m 3 . Until the sum of the three-shot penetration is less than 9cm.
It should be noted that: the standard of the single-click penetration is 3.5t column hammers, the drop distance is 6m, and the penetration refers to the difference between the penetration depth of the column hammers after the current hammering and the last penetration depth.
After bottom sealing 52, construction of pile body 51 is started, i.e., repeating "filling→tamping". The amount of filler (dry hard concrete 9 in a loose state) per time was 0.2m 3 ～0.3m 3 . After each filling, when the sum of the penetration of the last three shots is less than or equal to 9cm, the strength of the pile body 51 meets the requirement, and the filling can be continued upwards to tamp the pile. The concrete filling amount, the tamping times and the total filling amount can be determined by pile testing according to different stratum.
In the pile forming process, the pile body 51 is extruded outwards again, namely, the compacted hard concrete 9 bulges, and the bulges compact the surrounding soil of the pile, namely, the foundation soil 6 is compacted for the second time in the invention. Meanwhile, the protruding parts greatly increase the lateral friction force of the pile, which is beneficial to increasing the rigidity of the pile.
Construction sequence of each pile body 5: pile-by-pile construction is performed from the middle to the periphery, and finally the whole field is covered. If the construction is performed from the periphery to the middle, the foundation soil 6 in the middle is more compact, and finally, holes are difficult to be formed, and even the foundation soil 6 can rise upwards.
The double ramming expansion compaction hard concrete 9 pile is continuously compacting foundation soil 6 from hole forming to pile forming, and meanwhile, the pile body 51 is formed by repeated ramming, so that larger expansion force exists in the foundation soil 6 and the pile, particularly after the pile is constructed, the ground on the pile top can bulge to generate cracks, and the release is the result of upward release of a part of expansion force of the hard concrete 9 pile and the soil between the piles, and is practically equal to weakening of the compaction effect of the pile on the foundation soil 6. In order to avoid the release of the energy, a pile cap 4 is arranged on the pile top, and a reinforced cement soil layer 22 cushion layer 2 with the thickness of 500mm is arranged above the pile top, so that the capping of the composite foundation is realized.
(4) After the pile body 5 is constructed, a pile cap 4 is driven into the top end of the pile body 5 in a hammering mode, the pile cap 4 consists of L-shaped steel bars 41 and round cake-shaped concrete prefabricated parts 42, the thickness of the concrete prefabricated parts is 15cm, the diameter is generally 2 times of the diameter of the pile, the material is concrete, the strength grade C30 is built in 4 symmetrically arranged L-shaped steel bars 41, the diameter is 22mm, the long side of the L-shaped steel bars 41 is 50cm, the length of the short side is 30cm, the long side steel bars are partially exposed, and the end parts of the exposed steel bars are tapered so as to facilitate driving into the pile. If the pile cap 4 is difficult to drive into the pile body 5, an electric drill can be used for forming holes, the hole diameter is generally 20mm and slightly smaller than the diameter of the steel bars, and then the pile cap 4 is driven. The pile cap 4 increases the cross-sectional area of the pile, and can effectively prevent the pile from penetrating into the cushion layer 2 at the upper part of the pile under the action of the expansion force.
(5) After the pile caps 4 are constructed, a gravel layer 3 is paved between the pile anchors, and the thickness of the gravel layer 3 is equal to that of the pile caps 4. The effect of the crushed stone layer 3 is to dissipate the pore water pressure in the foundation soil 6 after piling. The soil often contains water, if the soil is compacted, the water is discharged, otherwise, the compaction is difficult. For example, the wet clothes are packed in the plastic bag, the plastic bag is sealed and squeezed, the wet clothes are difficult to compact under the action of water, if the plastic bag is provided with a plurality of small holes, the water can be discharged through the small holes in the process of squeezing the plastic bag by external force, and the clothes can be compact at the moment. Similarly, in the pile forming process, the foundation soil 6 is extruded by an external force, after the foundation soil 6 is extruded, water in the foundation soil 6 is accumulated, and if a drainage channel is not provided, the foundation soil 6 is difficult to compact. The crushed stone layer 3 serves as a drainage channel.
(6) After the pile cap 4 and the gravel layer 3 are constructed, the cushion layer 2 is immediately constructed, the common cushion layer 2 is improved into a reinforced cement soil layer 22 cushion layer 2, the cushion layer 2 is made of a layer of bidirectional geogrid 21 and a cement soil layer 22, wherein the bidirectional geogrid 21 is arranged in the cement soil layer 22, and the tensile strength of the bidirectional geogrid 21 is not less than 50kN/m. The cement soil layer 22 is formed by mixing cement and soil in a volume ratio of 3:7, and is formed by rolling, wherein the compaction coefficient is not lower than 0.92, and the thickness of the cushion layer 2 is 500mm. The bi-directional geogrid 21 has the properties of high tensile strength and low elongation, and the cement soil layer 22 also has higher cohesiveness than the common gravel cushion layer 2. The strength and the integrity of the cushion layer 2 can be greatly improved, the double-rammed dense dry hard concrete 9-pile composite foundation can be effectively sealed, and the pile body 5 and the foundation soil 6 are prevented from expanding upwards.
(7) And constructing the foundation 1 above the cushion layer.
Example III
The foundation soil of a residential building is partially filled with artificial soil, the plan view of the relative position is shown in fig. 14, and the sectional views of the building, the natural foundation soil and the artificial soil are shown in fig. 15.
The problem of this project is that natural foundation soil is better, can satisfy intensity and rigidity of building to the foundation, but artifical filling can not satisfy, need to carry out the foundation to artifical filling. The conventional foundation treatment scheme is to perform compaction pile (discrete material pile) construction firstly, so as to improve the strength and rigidity of artificial filling soil, and then perform cohesive strength pile construction, so that the strength and rigidity of the foundation can be greatly improved, and the strength and rigidity of the foundation can be met for the building, as shown in fig. 16. The processing scheme has the defects of long construction period, inspection after the compaction pile is constructed, bonding strength after the compaction pile is qualified, and time and labor waste due to the fact that two sets of equipment and personnel are needed for the discrete material pile and the pile with the bonding strength.
Aiming at the defects of the traditional scheme, the invention provides a double-ramming compaction hard concrete pile composite foundation and a construction method. The pile collecting and distributing body material pile and the pile with bonding strength are integrated, namely, foundation soil can be extruded and encrypted for the second time, the strength and rigidity of the foundation soil are improved, meanwhile, the pile body belongs to the pile with bonding strength, the pile has higher strength and rigidity, the strength and rigidity of the foundation soil and the pile body are improved finally, and the strength and rigidity of the reinforced composite foundation are improved maximally. In addition, most importantly, the invention can be directly applied to loose foundation soil, and improves the applicability of the pile with bonding strength. See fig. 17.
The application of the invention not only solves the problems, but also saves the construction period and the manufacturing cost compared with the traditional scheme. According to the on-site measurement data, the settlement value of the building is very small, uneven settlement does not occur, and the standard requirement is met. The utility of the invention is fully described.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
1. A composite foundation, characterized by: comprising the following steps:
the pile holes are arranged on the foundation, and are formed by column hammer impact; and
and the pile bodies are bonding strength piles which are formed by filling dry and hard concrete in the pile holes and tamping by using the column hammers.
2. The composite foundation of claim 1, wherein: still include pile cap, gravel layer and bed course, pile cap fixed connection in the top of pile body, the gravel layer shop in between the pile cap, the bed course lay the compaction in the gravel layer with the top of pile cap.
3. The composite foundation of claim 2, wherein: the pile body comprises a back cover and a pile body, wherein the back cover is fixedly connected with the bottom end of the pile body, and the diameter of the back cover is larger than that of the pile body.
4. A composite foundation according to claim 3, wherein: the outer side wall of the pile body is provided with a plurality of annular bulges in the depth direction.
5. The composite foundation of claim 4, wherein: the pile cap comprises a cake-shaped concrete prefabricated part and a plurality of L-shaped reinforcing steel bars, one end of each L-shaped reinforcing steel bar is buried and fixed in the corresponding cake-shaped concrete prefabricated part, the other end of each L-shaped reinforcing steel bar is fixedly connected to the top end of the pile body, and the diameter of the cake-shaped concrete prefabricated part is larger than that of the pile body.
6. The composite foundation of claim 5, wherein: the column hammer comprises a hammer body and a hammer head, wherein the hammer head can be detachably connected to the bottom of the hammer body, and the hammer head is a conical hammer head or a flat-bottom hammer head; the cushion layer comprises a cement soil layer and a bidirectional geogrid, wherein the bidirectional geogrid is arranged in the cement soil layer.
7. A method of constructing a composite foundation according to any one of claims 1 to 6, wherein: the method comprises the following steps:
striking the foundation with the column hammer until a designed hole depth is formed into the pile hole;
and casting the dry and hard concrete into the pile hole and hammering the pile body by using the column hammer.
8. The method for constructing a composite foundation according to claim 7, wherein: driving a pile cap into the top of the pile body after the pile body construction is completed; paving a gravel layer between the pile caps; and constructing cushion layers on the pile caps and the gravel layer.
9. The method for constructing a composite foundation according to claim 7, wherein: the pile body construction comprises a back cover construction and a pile body construction, wherein the back cover construction is to fill the pile hole with the dry hard concrete and hammer the pile hammer until the sum of three-click penetration is less than 9cm, form a back cover, further perform the pile body construction on the top of the back cover, namely repeat 'filling → tamping', and fill the pile hole with the dry hard concrete in an amount of 0.2m each time 3 ～0.3m 3 After each filling, the filling can be continued to be tamped upwards until the pile body is completed until the sum of the last three penetrating degrees is less than or equal to 9cm.
10. The method for constructing a composite foundation according to claim 7, wherein: the construction sequence of each pile body is pile-by-pile construction from the middle to the periphery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311186059.XA CN117449280A (en) | 2023-09-14 | 2023-09-14 | Composite foundation and construction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311186059.XA CN117449280A (en) | 2023-09-14 | 2023-09-14 | Composite foundation and construction method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117449280A true CN117449280A (en) | 2024-01-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311186059.XA Pending CN117449280A (en) | 2023-09-14 | 2023-09-14 | Composite foundation and construction method |
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| Country | Link |
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| CN (1) | CN117449280A (en) |
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- 2023-09-14 CN CN202311186059.XA patent/CN117449280A/en active Pending
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