Composite foundation structure

Abstract

The utility model discloses a composite foundation structure, and relates to the technical field of building foundations, the composite foundation structure comprises a cement mixing soil layer, a geotechnical cloth layer and a plurality of groups of cluster piles which are arranged from top to bottom along the gravity direction, each group of cluster piles extends along the gravity direction, and each group of cluster piles is formed by binding at least three pine piles. According to the composite foundation structure, the pine piles which do not decay when encountering water are used for replacing existing steel piles and cement piles, cost can be reduced, and construction is more convenient; the multiple sets of bundling piles formed by binding the multiple pine piles are used on the lowermost layer, operation is easy, compared with a traditional single pine pile structure, the bearing capacity and strength are improved, the formed composite foundation structure is easy to operate and machine, the reinforcing effect is good, the input cost is low, and the construction efficiency can be greatly improved while the engineering quality is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of building foundations, in particular to a composite foundation structure. Background Art

[0002] With the continuous development of infrastructure construction in my country, a large number of construction projects, road projects, water conservancy projects, etc. need to be built on soft soil foundations. Soft soil foundations have the characteristics of large void ratio, high water content, large settlement, etc., and their compressibility is large, their strength is extremely low, and their foundation bearing capacity is low. They are not suitable for the construction of road projects, water conservancy projects, etc., and the soft soil foundation needs to be reinforced before construction.

[0003] In the related art, pine piles are generally used in composite foundation structures for reinforcing soft soil foundations. Pine piles are prone to breakage when subjected to stress, resulting in low foundation bearing capacity and large foundation trench excavation volume. Utility Model Content

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a composite foundation structure, which has a simple structure, high rigidity, strong penetration ability, high bearing capacity, good foundation reinforcement effect, low investment cost, broad application prospects, and can greatly improve construction efficiency while ensuring project quality.

[0005] A composite foundation structure provided by the utility model includes:

[0006] Cement-mixed soil layers, geotextile layers and multiple groups of clustered piles are laid out from top to bottom along the direction of gravity;

[0007] Each group of cluster piles extends along the gravity direction, and each group of cluster piles is formed by bundling at least three pine wood piles.

[0008] The composite foundation structure according to the embodiment of the utility model has at least the following beneficial effects:

[0009] The composite foundation structure of the present application uses pine piles that do not rot when exposed to water to replace existing steel piles and cement piles, which can reduce costs and make construction more convenient. A plurality of groups of clustered piles formed by bundling a plurality of pine piles are used in the bottom layer, which is easy to operate and has improved bearing capacity and strength compared with the traditional single pine pile structure. The composite foundation structure formed is easy to operate and process, has a good reinforcement effect, and has a low investment cost. While ensuring the quality of the project, it can greatly improve the construction efficiency.

[0010] According to some embodiments of the utility model, each of the pine wood piles has a top and a bottom, the diameter of the top is smaller than the diameter of the bottom, and in each group of clustered piles, the tops of multiple pine wood piles are staggered up and down.

[0011] The bottom end of each group of cluster piles is provided with a pile tip, which is connected to each of the pine wood piles.

[0012] According to some embodiments of the present invention, the pile tip includes a plurality of angle steels, each of which is inserted into one of the pine wood piles.

[0013] According to some embodiments of the present invention, the cluster piles include binding members, and the binding members are tied to the outer periphery of all the pine wood piles;

[0014] Furthermore, along the gravity direction, each group of cluster piles is provided with a plurality of the binding members at intervals.

[0015] According to some embodiments of the present invention, between the multiple groups of cluster piles, the arrangement interval between each two adjacent cluster piles is 0.8-1.5 m.

[0016] According to some embodiments of the present utility model, the cement-mixed soil layer includes a geogrid and cement-mixed soil, and the geogrid integrally wraps the cement-mixed soil.

[0017] According to some embodiments of the present invention, the geogrid is a double-layer structure; and / or the hole size of the geogrid is less than or equal to 5 cm; and / or the material of the geogrid includes polypropylene.

[0018] According to some embodiments of the present invention, the thickness of the cement-mixed soil satisfies greater than or equal to 500 mm and less than or equal to 800 mm; and / or, the cement content of the cement-mixed soil satisfies greater than or equal to 6% and less than or equal to 12%; and / or, the cement-mixed soil is compacted in layers.

[0019] According to some embodiments of the present invention, the geotextile layer is laid on the bottom of the geogrid, and the weight per square meter is greater than or equal to 200 grams.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0022] Figure 1 This is a structural schematic diagram of a composite foundation structure according to an embodiment of the utility model;

[0023] Figure 2 for Figure 1 A schematic diagram of a first example cross-sectional structure of a cluster pile of a composite foundation structure;

[0024] Figure 3 for Figure 1 A schematic diagram of a second example cross-sectional structure of a cluster pile of a composite foundation structure;

[0025] Figure 4 for Figure 1 A schematic diagram of a third example cross-sectional structure of cluster piles of a composite foundation structure;

[0026] Figure 5 for Figure 1 A schematic diagram of a fourth example cross-sectional structure of cluster piles of a composite foundation structure;

[0027] Figure 6 for Figure 1 Schematic diagram of the structure of the pile tip of the composite foundation structure.

[0028] Figure Number:

[0029] 100. Composite foundation structure;

[0030] 10. Cement-mixed soil layer; 11. Geogrid; 12. Cement-mixed soil; 20. Geotextile layer; 30. Cluster piles; 31. Pine piles; 32. Pile tip; 321. Angle steel; 322. Main body; 33. Binding parts; G, direction of gravity. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] In the description of the present invention, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of the present utility model, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0034] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0035] With the rapid expansion of urban municipal roads from urban areas to suburbs, when building roads in tidal flats and fill areas, it is necessary to solve the soft soil foundation problems such as the fill layer and silt layer at the base of the roadbed, pipelines (rain, sewage pipes, cable trenches, etc.). Usually, when the thickness of the soft soil at the base is less than 3m, a shallow replacement treatment is adopted, and the structure layer after replacement is used as the foundation structure layer. When the thickness of the soft soil at the base is greater than 3m, the replacement treatment will bring about problems such as precipitation, foundation pit support, and a significant increase in costs. After cement soil mixing piles, pipe piles and other deep structures are driven into the base, gravel and crushed stone cushion layers are laid on the top of the piles to form a composite foundation structure, and the composite foundation is used as the foundation structure layer. This stratum structure layer has the characteristics of high foundation bearing capacity and small post-construction settlement. However, the construction cost of this composite foundation is high and the construction difficulty increases.

[0036] In order to reduce costs and construction difficulty, related technologies use pine piles to form a composite foundation structure. However, the pine pile structure has a small foundation bearing capacity and is prone to breaking when penetrating the silt layer and entering the underlying hard soil layer. At the same time, there are problems such as excessive excavation depth of the foundation pit and a large amount of abandoned soil in the foundation pit.

[0037] Based on this, see Figure 1 The present application provides a composite foundation structure 100, including a cement mixed soil layer 10, a geotextile layer 20 and a plurality of cluster piles 30 arranged from top to bottom along a gravity direction G, each cluster pile 30 extends along the gravity direction G, and each cluster pile 30 is formed by bundling at least three pine wood piles 31.

[0038] Each bundle of clustered piles 30 forms a separate supporting structure, that is, it is considered that, in the composite foundation structure 100 of the present application, each bundle of clustered piles 30 forms an indivisible unit, and each unit performs a supporting function separately. Each bundle of clustered piles 30 is formed by bundling 3 or more pine piles 31, for example, 3, 4, 5, 6, 7, 8, 9, 10, etc., and the specific number needs to be selected according to the actual foundation space.

[0039] In some embodiments, considering the compactness between the cluster piles 30 and the construction equipment, refer to Figures 2 to 5 The cluster piles 30 are usually formed by 3 pine piles 31, 4 pine piles 31, 7 pine piles 31, and 9 pine piles 31, so that the bundled cluster piles 30 have a compact structure, good stability and strong density.

[0040] Specifically, the diameter of each pine pile 31 can be 12 to 15 cm. When selecting, choose a complete pine pile 31 that is straight and has no scars, cracks, insect bites, rot or other undesirable phenomena. The pine pile 31 is peeled and carbonized, and then the pine piles 31 are bundled with a corresponding structure. After the bundling is completed, the protruding parts of the heads and tails of the clustered piles 30 are cut flat, and the clustered pine piles 31 are driven into the bearing layer to a certain depth in the direction perpendicular to the soil (i.e., the gravity direction G).

[0041] In this way, the composite foundation structure 100 provided by the present application uses pine piles 31 that do not rot when exposed to water to replace existing steel piles and cement piles, which can reduce costs and make construction more convenient; and a plurality of groups of clustered piles 30 formed by bundling a plurality of pine piles 31 are used in the bottom layer, which is simple to operate and has improved bearing capacity and strength compared to the traditional single pine pile structure. The formed composite foundation structure 100 is simple to operate and process, has a good reinforcement effect, and has a low investment cost. While ensuring the quality of the project, it can greatly improve the construction efficiency.

[0042] In one embodiment, each pine wood pile 31 has a top and a bottom, the diameter of the top is smaller than the diameter of the bottom, and in each group of cluster piles 30, the tops of the plurality of pine wood piles 31 are staggered and distributed up and down.

[0043] Generally, along the axial direction of the pine wood pile 31, the pine wood pile 31 is a conical pile with uneven upper and lower diameters, that is, one end is thick and the other end is thin, the thicker end forms a bottom end with a larger diameter, and the thinner end forms a top with a smaller diameter. When bundling to form the pine wood pile 31, if the tops and bottoms of multiple pine wood piles 31 are aligned for bundling, the axial upper and lower dimensions of the cluster pile 30 will be inconsistent, with a small size at the top and a large size at the bottom.

[0044] Therefore, in order to ensure that the cluster piles 30 have the same size from top to bottom, the tops of the multiple pine piles 31 in each group of cluster piles 30 are staggered up and down. For example, when the technical equipment uses three pine piles 31, the tops of two pine piles 31 are aligned with the bottom of one pine pile 31, and at the other end, the bottoms of two pine piles 31 are aligned with the top of one pine pile 31.

[0045] In one embodiment, see Figure 1 and Figure 6 A pile tip 32 is provided at the bottom end of each group of cluster piles 30, and the pile tip 32 is connected to each pine pile 31. The pile tip 32 has the function of enhancing the penetration ability of the cluster pile 30 and improving the end bearing capacity of the cluster pile 30. After the cluster piles 30 are bundled, the pile tip 32 is connected to each pine pile 31, so that the tip of the pile tip 32 extends into the soft soil foundation to speed up the construction progress.

[0046] Specifically, the pile tip 32 can be a prefabricated part, for example, it can be formed by a reinforced concrete structure, the concrete grade is not less than C25, and structural steel bars are configured. The tip of the pile tip 32 is a nearly conical structure, and the top surface is a polygon. The shape and size of the top surface are basically the same as the cross-sectional shape and size of the cluster pile 30, so as to facilitate the connection between the pile tip 32 and the pine pile 31.

[0047] For example, the cross-section of the cluster pile 30 formed by bundling three pine wood piles 31 is approximately an equilateral triangle, and the top surface of the pile tip 32 is approximately an equilateral triangle, for example, an equilateral triangle with a side length of 25 cm, and the height of the pile tip 32 in the gravity direction G is also 25 cm to facilitate processing.

[0048] In some embodiments, see Figure 6 The pile tip 32 includes a body 322 and a plurality of angle steels 311. As described above, the body 322 may be formed of a reinforced concrete structure, and a plurality of angle steels 311 are embedded in the top surface of the body 322. Each angle steel 311 is inserted into a pinewood pile 31 to limit the position between the pile tip 32 and the pinewood pile 31. Specifically, the angle steel 311 may be an equilateral angle steel 311, for example, with a side length of 30 mm and an exposed length of 15 to 20 cm.

[0049] In one embodiment, the cluster piles 30 include binding members 33, which are tied to the outer periphery of all pine piles 31 along the gravity direction G. Each group of cluster piles 30 is arranged with multiple binding members 33 at intervals to bind and constrain the pine piles 31 at multiple positions along the gravity direction G to ensure the structural stability of the cluster piles 30.

[0050] Specifically, the binding member 33 may be a galvanized stainless steel hoop, or may be a plurality of galvanized iron wires with a diameter of not less than 2 mm. Along the gravity direction G, a binding member 33 is provided at intervals of 1 m, so as to evenly bind the plurality of pine wood piles 31 .

[0051] In one embodiment, a certain gap, for example, 20 cm, must be reserved between the uppermost binding member 33 and the top of the cluster pile 30 to ensure that the angle steel 311 can be inserted into the pine pile 31 .

[0052] In a specific embodiment, the spacing between each two adjacent cluster piles 30 is 0.8-1.5 m, and the cluster piles 30 are arranged in a square or equilateral triangle, thereby improving the stability and bearing strength of the foundation as a whole.

[0053] Specifically, see Figures 2 to 5 The arrangement spacing of each two adjacent cluster piles 30 refers to the horizontal line between the center points 0 of each two adjacent cluster piles 30, thereby forming a unified reference to calculate the arrangement spacing of each two adjacent cluster piles 30.

[0054] In one embodiment, the cement-mixed soil layer 10 includes a geogrid 11 and cement-mixed soil 12 , and the geogrid 11 integrally wraps the cement-mixed soil 12 .

[0055] Cement-mixed soil 12 refers to a material formed by mixing cement and soil in a certain ratio using cement as a binder. Cement-mixed soil 12 is a multifunctional soil material with good mechanical properties, such as excellent compressive strength and bending strength. At the same time, cement-mixed soil 12 also has good processability, anti-permeability and durability, thereby improving the structural strength of the composite foundation structure 100.

[0056] The construction technology of cement mixed soil 12 needs to pay attention to the following points: First, it is necessary to control the ratio of cement to soil and formulate a reasonable ratio plan. Secondly, it is necessary to fully stir during the mixing process, even if the ground mud is uniform. Finally, during construction, appropriate construction machinery and methods should be selected according to the specific situation, such as using a vibrator or a roller for compaction. Of course, environmental protection and engineering safety measures need to be taken during the construction process to ensure that the cement mixed soil 12 is well applied and the construction quality is guaranteed.

[0057] Geogrid 11 is a new type of geotechnical material, mainly used for soil reinforcement and stabilization. It has the characteristics of light weight, high tensile strength, chemical corrosion resistance, corrosion resistance, good isolation, etc. It can effectively prevent soil erosion and landslides and protect the ecological environment.

[0058] Geogrid 11 wrapping is a common geogrid 11 reinforcement technology, which is to add a layer of specific material on the back of the geogrid 11 to enhance the tensile strength and stability of the geogrid 11. The principle is to cover the geogrid 11 with cement mixed soil 12 from the back, so that the concentrated strength of the geogrid 11 is improved, and it can also play a certain protective role, making it more durable.

[0059] In this way, the cement-mixed soil 12 is entirely wrapped by the geogrid 11 , thereby improving the structural strength of the cement-mixed soil layer 10 .

[0060] Specifically, the geogrid 11 is integrally covered with cement mixed soil 12, the overlap length of each section of the geogrid 11 and the sealing portion is not less than 30 cm, and the sealing portion is tied with professional tying wire.

[0061] In one embodiment, the thickness of the cement-mixed soil 12 satisfies greater than or equal to 500 mm and less than or equal to 800 mm, and / or the cement content of the cement-mixed soil 12 satisfies greater than or equal to 6% and less than or equal to 12%; and / or the cement-mixed soil 12 is compacted in layers.

[0062] The soil material used for the cement-mixed soil 12 is preferably the on-site excavated soil, and the amount of cement added is determined according to the moisture content of the on-site soil, which is not specifically limited in this application. After the cement is added to the soil, it should be mixed evenly so that there is no agglomeration inside the cement-mixed soil 12. When there are debris such as lumps and construction waste in the soil, they should be removed.

[0063] Then, the cement-mixed soil 12 is compacted or rolled in layers, the thickness of the layered rolling or compaction is controlled within 300 mm, and the compaction coefficient is not less than 0.97, so as to ensure the structural strength of the cement-mixed soil 12.

[0064] In other embodiments, when the bare soil excavated from the foundation pit cannot be used as the raw material for cement-soil mixture due to geological conditions, the bare soil in the cement-soil mixture 12 can be replaced by stone powder slag or medium-coarse sand, and this application does not impose any restrictions thereon.

[0065] In one embodiment, the geogrid 11 is a double-layer structure; and / or the hole size of the geogrid 11 is less than or equal to 5 cm, and / or the material of the geogrid 11 includes polypropylene.

[0066] Geogrids 11 are divided into four categories: plastic geogrids, steel-plastic geogrids, glass fiber geogrids, and polyester warp-knitted polyester geogrids. The grid is a two-dimensional grid or a three-dimensional grid screen with a certain height made of high molecular polymers such as polypropylene and polyvinyl chloride through thermoplasticization or molding, thereby forming a double-layer geogrid 11 with better fixing and shaping effect.

[0067] In one embodiment, the geotextile layer 20 is laid on the top of the cluster pile 30 and the bottom of the geogrid 11, so as to isolate the soil. Specifically, the geotextile can be a woven geotextile with a weight of not less than 200 grams per square meter.

[0068] For ease of description, a specific construction process of the composite foundation structure 100 is provided below:

[0069] (1) Level the site;

[0070] (2) excavation of foundation trench, specifically, digging a pit on the leveled site to form a foundation trench;

[0071] (3) Positioning and laying out the lines to facilitate the subsequent positioning of the pile driving position of the cluster pile 30;

[0072] (4) Construction of cluster piles 30. Specifically, a special pile driver for pine piles 31 can be used for the construction of cluster piles 30. The driving capacity meets the requirements. The pile tip 32 is buried in a groove after positioning and laying out. The burial depth is suitable for the pile tip 32 not to fall over. The position deviation of the pile tip 32 is not more than 10 cm. The verticality tolerance of each bundle of cluster piles 30 is less than 1%.

[0073] In order to achieve a good compaction effect and improve the bearing capacity, the piling route is symmetrically driven from the outside to the middle. During the piling process, the driving speed should be slowed down after the pile tip 32 passes through the soft soil and enters the stable bearing layer to avoid excessive pressure damaging the cluster pile 30. After the pine pile 31 is driven, the exposed excess pile head on the top of the cluster pile 30 is sawed off to make the top of the cluster pile 30 flush with the bottom surface of the foundation trench (i.e., the super-flat pile top elevation hereinafter).

[0074] (5) Super-flat pile top elevation. It should be noted that the super-flat pile top elevation is to saw flat the pile head at the top of the cluster pile 30 so that the top of the cluster pile 30 is flush with the bottom surface of the foundation trench, which is convenient for the subsequent laying of the geotextile layer 20.

[0075] (6) Laying the geotextile layer 20 . Specifically, the geotextile should be spread flat. Before laying, sharp objects such as stubble and stones should be removed to avoid puncturing the geotextile layer 20 .

[0076] (7) Laying the geogrid 11. Specifically, the geogrid 11 should be spread flat and tight, and fixed firmly with special U-shaped nails inserted every 1.0m.

[0077] (8) Layered rolling of cement mixed soil 12;

[0078] (9) Sealing of geogrid 11.

[0079] In this way, the construction of the entire composite foundation structure 100 is completed. The foundation structure is simple, the composite foundation structure 100 has high rigidity, strong penetration ability, high bearing capacity, good foundation reinforcement effect, low investment cost, and broad application prospects. While ensuring the quality of the project, it can greatly improve the construction efficiency.

[0080] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A composite foundation structure, characterized in that: include: Cement-mixed soil layers, geotextile layers and multiple groups of clustered piles are laid out from top to bottom along the direction of gravity; Each group of cluster piles extends along the gravity direction, and each group of cluster piles is formed by bundling at least three pine wood piles.

2. The composite foundation structure according to claim 1, characterized in that: Each of the pine wood piles has a top and a bottom, the diameter of the top is smaller than the diameter of the bottom, and in each group of clustered piles, the tops of the plurality of pine wood piles are staggered and distributed up and down.

3. A composite foundation structure according to claim 1, characterized in that: The bottom end of each group of cluster piles is provided with a pile tip, which is connected to each of the pine wood piles.

4. A composite foundation structure according to claim 3, characterized in that: The pile tip includes a plurality of angle steels, each of which is inserted into one of the pine wood piles.

5. A composite foundation structure according to claim 1, characterized in that: The cluster piles include a binding piece, and the binding piece is bound around the outer circumference of all the pine wood piles; Furthermore, along the gravity direction, each group of cluster piles is provided with a plurality of the binding members at intervals.

6. A composite foundation structure according to claim 1, characterized in that: Between multiple groups of cluster piles, the spacing between each two adjacent cluster piles is 0.8 to 1.5 m.

7. A composite foundation structure according to claim 1, characterized in that: The cement-mixed soil layer includes a geogrid and cement-mixed soil, and the geogrid integrally wraps the cement-mixed soil.

8. A composite foundation structure according to claim 7, characterized in that: The geogrid has a double-layer structure; and / or the size of the holes in the geogrid is less than or equal to 5 cm; And / or, the material of the geogrid includes polypropylene.

9. A composite foundation structure according to claim 7, characterized in that: The thickness of the cement-mixed soil is greater than or equal to 500 mm and less than or equal to 800 mm; And / or, the cement content of the cement-mixed soil satisfies a content greater than or equal to 6% and less than or equal to 12%; And / or, the cement-mixed soil is compacted layer by layer.

10. A composite foundation structure according to claim 7, characterized in that: The geotextile layer is laid on the bottom of the geogrid, and has a weight of greater than or equal to 200 grams per square meter.

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