Large-spacing tubular pile mattress layer structure and construction method thereof

Abstract

The invention relates to a large-spacing tubular pile mattress layer structure and a construction method thereof. Due to the fact that an existing mattress layer is made of a single-form geotechnical material, and generally, the mattress layer is not provided with a geogrid cushion layer between pile caps, the effects of controlling differential settlement and improving the bearing capacity of the mattress layer are poor, and the mattress layer is not suitable for large-interval pipe piles. The composite geogrid cushion layer structure comprises a composite geogrid cushion layer area between pile caps, a pile top high-strength geocell cushion layer area and a pile top composite geogrid cushion layer area. The composite geogrid cushion layer area between the pile caps comprises a composite geogrid laid above the pile body and a first broken stone cushion layer flush with the pile caps in elevation. The pile top high-strength earthwork standard room cushion layer area comprises a high-strength earthwork standard room and a second broken stone cushion layer; the pile top composite geogrid cushion layer area comprises a composite geogrid and a third gravel cushion layer. According to the large-spacing pipe pile mattress layer, the two geotechnical materials and the gravel are combined to form the mattress layer structure, the effect of controlling differential settlement and improving the bearing capacity of the mattress layer is greatly improved, and the large-spacing pipe pile mattress layer is suitable for a soft soil area.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a large-spacing pipe pile mattress layer structure and a construction method thereof. Background Art

[0002] At present, composite foundation has been widely used in civil engineering as one of the means to deal with soft soil foundation. In the design of composite foundation, a cushion layer composed of a certain thickness of loose granular materials and geotechnical materials is set between the foundation and the piles and the soil between the piles, which is a core technology of the composite foundation. Whether a cushion layer is set under the foundation has a great influence on the stress of the composite foundation. If a cushion layer is not set, the bearing characteristics of the composite foundation are similar to those of the pile foundation, and the bearing capacity of the soil between the piles is difficult to play, and it cannot become a composite foundation. If a cushion layer is set under the foundation, the bearing capacity of the soil between the piles will not only rely on the settlement of the piles, but the piles and soil will bear the load together through the action of the cushion layer.

[0003] In soft soil areas, if a higher foundation bearing capacity and better control of foundation settlement are required, rigid piles and pipe piles with higher bearing capacity are generally used for foundation treatment. The existing technology uses rigid piles + pile caps + geogrids to form a pile-soil coordinated pile-net composite foundation. The pile spacing of the pile-net composite foundation is generally 2 to 3m. After the pile cap is constructed on the top of the pile, the geogrid is laid to coordinate the settlement of the soil between the piles. However, in deep soft soil areas, the thickness reaches more than 10m, the pile end must pass through the silt, and the pile length may reach more than 15m. At present, there are new large-diameter pipe piles that expand the pile spacing to a large spacing of 3 to 4m. Since the existing cushion layer uses a single form of geotechnical material, such as geogrids or geocells to control uneven settlement, it is either lacking in safety or uneconomical, and usually the cushion layer structure does not have a geogrid cushion layer between the pile caps, so that the cushion layer has a weak effect of controlling uneven settlement and improving bearing capacity. If it is used for large-spacing pipe piles, there is a risk of soft soil settlement between the pile caps, so the existing cushion layer is not suitable for large-spacing pipe piles.

[0004] Therefore, there is an urgent need for a new cushion layer suitable for large-spacing pipe piles. Summary of the invention

[0005] The object of the present invention is to provide a large-spacing pipe pile cushion layer structure and a construction method thereof, so as to at least solve the problems of the prior art that the form is single and the effect of controlling uneven settlement and improving bearing capacity is weak.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A cushion layer structure of large-spacing pipe piles, wherein the cushion layer is laid on the pile body of the composite foundation, and the cushion layer is a combined cushion layer, including a composite geogrid cushion layer area between pile caps, a high-strength geocell cushion layer area on the pile top, and a composite geogrid cushion layer area on the pile top;

[0008] The composite geogrid cushion layer area between the pile caps includes a composite geogrid laid on the pile body and a first crushed stone cushion layer laid on the composite geogrid and at the same level as the pile cap elevation;

[0009] The pile top high-strength geocell cushion layer area includes a high-strength geocell laid on the first crushed stone cushion layer and a second crushed stone cushion layer laid on the high-strength geocell;

[0010] The pile top composite geogrid cushion layer area includes a composite geogrid laid on the second crushed stone cushion layer and a third crushed stone cushion layer laid on the composite geogrid.

[0011] Furthermore, the composite geogrid includes a plurality of large hexagons.

[0012] Furthermore, the large hexagon contains a plurality of meshes formed by ribs, and the shapes of the meshes are hexagonal, trapezoidal and triangular.

[0013] Furthermore, the cross-sectional shape of the rib is rectangular.

[0014] Furthermore, the antioxidant strength retention rate, the UV resistance strength retention rate and the acid and alkali resistance strength retention rate of the composite geogrid are all ≥90%.

[0015] Furthermore, the high-strength geocell comprises a plurality of cell sheets and a plurality of connectors, wherein the plurality of connectors are arranged in parallel, and the plurality of cell sheets are respectively connected obliquely between adjacent connectors.

[0016] Furthermore, the connecting member includes a plurality of U-shaped plug-ins, and the plurality of U-shaped plug-ins are connected to form a wave shape.

[0017] Furthermore, the cell sheet is a rectangular parallelepiped, one end of the cell sheet is connected to the U-shaped bottom of the U-shaped plug-in of the connector, and the other end is connected to the open end of the U-shaped plug-in of the adjacent connector.

[0018] Furthermore, the height of the cell sheet is 4-6 cm.

[0019] The construction method of the large-spacing pipe pile cushion structure is as follows:

[0020] Construct the pile body, maintain it to the specified strength and pass the acceptance inspection, and then construct the pile cap;

[0021] A layer of composite geogrid is manually laid between the pile caps, and the first crushed stone cushion is backfilled to the same level as the pile cap elevation;

[0022] A layer of high-strength geocell is manually laid on top of the first crushed stone cushion layer, and the second crushed stone cushion layer is mechanically spread and leveled and compacted;

[0023] A layer of composite geogrid is manually laid on top of the second crushed stone cushion layer, and the third crushed stone cushion layer is mechanically spread and leveled and compacted.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention designs a cushion structure for improving the soil arch effect for large-spacing pipe piles, adopts a cushion structure composed of two geotechnical materials and crushed stone, and lays a composite geogrid in the cushion between the pile caps, while taking into account the high-strength performance of the geocell required at the bottom and the uneven settlement control performance of the two more economical composite geogrids at the top, and adopts the composite geogrid and high-strength geocell to achieve the purpose of better foundation treatment, while avoiding the uneconomical use of all high-strength geocells, meeting both safety and economic requirements. The combined cushion structure of the present invention can greatly improve the effect of the cushion layer in controlling uneven settlement and improving bearing capacity, avoid soft soil settlement caused by excessive pile spacing, is suitable for large-spacing pipe piles in soft soil areas, and can also expand the pile spacing, reduce the number of pile foundations, and reduce the project cost by more than 30%, with good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying creative work.

[0027] Figure 1 is a schematic elevation diagram of the present embodiment during construction;

[0028] Figure 2 It is a cross-sectional schematic diagram of this embodiment;

[0029] Figure 3 It is a plan view of composite geogrid;

[0030] Figure 4 It is a schematic diagram of the cross section of the composite geogrid rib;

[0031] Figure 5 It is a schematic diagram of a high-strength geocell structure;

[0032] The symbols in the figure are:

[0033] 1-cushion layer, 2-composite geogrid cushion area between pile caps, 21-first crushed stone cushion layer, 3-high-strength geocell cushion area on pile top, 31-second crushed stone cushion layer, 4-composite geogrid cushion area on pile top, 41-third crushed stone cushion layer, 5-composite geogrid, 6-high-strength geocell, 61-cell sheet, 62-connector, 7-embankment fill area, 8-pile-soil area, 9-pile body. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0035] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position 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.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Meanwhile, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. Of course, such objects can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0038] In the description of the present invention, it should be understood that multiple steps are involved in the process of describing the method, which should not be understood as a limitation on the order of the method steps. When solving the same technical problem, the technical solution obtained by only changing the order of the steps is also within the scope of protection of the present invention.

[0039] Example:

[0040] like Figure 1As shown, this embodiment provides a cushion layer structure of large-spacing pipe piles, wherein the cushion layer 1 is arranged between the embankment fill area 7 and the pile-soil area 8, and the cushion layer 1 is a composite cushion layer, which adopts a composite structure of two geotechnical materials and crushed stone, and a geogrid is laid in the cushion layer between the pile caps, that is, a high-strength geocell 6 is adopted at the bottom, and two layers of relatively economical clamped composite geogrids 5 are adopted at the upper and lower parts, so as to give full play to the respective properties of the two materials, meet the safety requirements, and take into account the economy.

[0041] like Figure 2 As shown, the cushion layer 1 includes a composite geogrid cushion area 2 between pile caps, a high-strength geocell cushion area 3 on the pile top and a composite geogrid cushion area 4 on the pile top. The composite geogrid cushion area 2 between pile caps is arranged above the pile body 9 of the pile-soil area 8, the high-strength geocell cushion area 3 on the pile top is arranged above the composite geogrid cushion area 2 between pile caps, and the composite geogrid cushion area 4 on the pile top is arranged above the high-strength geocell cushion area 3 on the pile top.

[0042] The composite geogrid cushion area 2 between pile caps includes a composite geogrid 5 laid on the pile body 9 and a first crushed stone cushion layer 21 laid on the composite geogrid 5 and flush with the pile cap elevation. The composite geogrid 5 and the first crushed stone cushion layer 21 are laid between adjacent pile bodies 9 and are arranged at equal intervals. The high-strength geocell cushion area 3 on the pile top includes a high-strength geocell 6 laid on the first crushed stone cushion layer 21 and a second crushed stone cushion layer 31 laid on the high-strength geocell 6. The composite geogrid cushion area 4 on the pile top includes a composite geogrid 5 laid on the second crushed stone cushion layer 31 and a third crushed stone cushion layer 41 laid on the composite geogrid 5.

[0043] Further, such as Figure 3 As shown, the composite geogrid 5 is formed as a whole by punching and directional stretching of three-layer co-extruded composite polymer plates. The composite geogrid 5 includes a plurality of large hexagons, each of which contains a plurality of meshes formed by continuous and discontinuous ribs. The mesh shapes are hexagonal, trapezoidal and triangular.

[0044] Each large hexagon contains seven medium hexagons, which are arranged in three rows, with two medium hexagons in the upper row, three medium hexagons in the middle row, and two medium hexagons in the lower row. Triangular meshes are formed between adjacent medium hexagons. Each medium hexagon contains a small hexagonal mesh and six trapezoidal meshes. The small hexagonal mesh is located in the center of the medium hexagon, and the six trapezoidal meshes are distributed in a circle around the small hexagonal mesh.

[0045] like Figure 4 As shown, the cross-section of the rib is rectangular, and the radial tensile secant modulus at 2% strain is ≥130 kN / m.

[0046] The antioxidant strength retention rate, the UV resistance strength retention rate and the acid and alkali resistance strength retention rate of the composite geogrid 5 are all ≥90%.

[0047] Further, such as Figure 5 As shown, the high-strength geocell 6 includes a plurality of cell sheets 61 and a plurality of connectors 62 , and the whole is a plurality of honeycomb-shaped three-dimensional grid structures. The plurality of connectors 62 are arranged in parallel, and the plurality of cell sheets 61 are obliquely connected between adjacent connectors 62 .

[0048] The connecting member 62 is formed by connecting a plurality of U-shaped plug-ins, and the plurality of U-shaped plug-ins are connected to form a wave shape.

[0049] The cell sheet 61 is a rectangular parallelepiped, one end of the cell sheet 61 is connected to one side of the U-shaped bottom of the connector 62 U-shaped plug-in, and the other end is connected to one side of the opening of the adjacent connector 62 U-shaped plug-in. The adjacent cell sheets 61 are symmetrically arranged in an eight-shaped shape, and the cell sheet 61 is 5 cm high.

[0050] The high-strength geocell 6 is made of polyester, the tensile strength of the nodes of the high-strength geocell 6 is ≥1700N / cm, the longitudinal pull-out force of the node bending U-shaped plug-in is ≥700N, and the transverse peeling force of the open end of the node U-shaped plug-in is ≥300N; the breaking tensile force per unit width of the cell sheet 61 is ≥1700N / cm, and the corresponding elongation of the cell sheet 61 is ≤10%; the effective lateral constraint height of the high-strength geocell 6 after tensioning is uniform, and the minimum lateral constraint height is >5cm.

[0051] In this embodiment, a composite geogrid 5 cushion layer is arranged between the pile caps, which takes advantage of the high strength performance of the geocell required at the bottom and the uneven settlement control performance of the two relatively economical composite geogrids 5 at the top, thereby greatly improving the bearing capacity of the soft soil between the pile bodies 9 and the effect of controlling uneven settlement, avoiding the soft soil settlement caused by the excessive spacing between the pile bodies 9. It is suitable for the cushion layer of large-spacing pipe piles in soft soil areas, and can also expand the spacing between the pile bodies 9, reduce the number of pile foundations, and reduce the project cost by more than 30%, thereby having good economic benefits.

[0052] The construction method steps of this embodiment are as follows:

[0053] The pile body 9 is constructed and maintained to a specified strength and accepted, and then the pile cap is constructed;

[0054] A layer of composite geogrid 5 is manually laid between the pile caps, and the first crushed stone cushion layer 21 is backfilled to the same level as the pile cap elevation;

[0055] A layer of high-strength geocell 6 is manually laid on the first crushed stone cushion layer 21, and the second crushed stone cushion layer 31 is mechanically spread and leveled and compacted;

[0056] A layer of composite geogrid 5 is manually laid on the second crushed stone cushion layer 31, and the third crushed stone cushion layer 41 is mechanically spread and leveled and compacted.

[0057] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A cushion layer structure of large-spacing pipe piles, wherein the cushion layer (1) is laid on the pile body (9) of the composite foundation, and is characterized by: The cushion layer (1) is a combined cushion layer, comprising a composite geogrid cushion layer area (2) between pile caps, a high-strength geocell cushion layer area (3) on the pile top, and a composite geogrid cushion layer area (4) on the pile top; The composite geogrid cushion layer area (2) between the pile caps comprises a composite geogrid (5) laid on the pile body (9) and a first crushed stone cushion layer (21) laid on the composite geogrid (5) and at the same level as the pile cap elevation; The pile top high-strength geocell cushion layer area (3) comprises a high-strength geocell (6) laid on top of the first crushed stone cushion layer (21) and a second crushed stone cushion layer (31) laid on top of the high-strength geocell (6); The pile top composite geogrid cushion layer area (4) comprises a composite geogrid (5) laid on top of the second crushed stone cushion layer (31) and a third crushed stone cushion layer (41) laid on top of the composite geogrid (5).

2. The large-spacing pipe pile cushion structure according to claim 1 is characterized in that: The composite geogrid (5) comprises a plurality of large hexagons.

3. The large-spacing pipe pile cushion structure according to claim 2 is characterized in that: The large hexagon contains a plurality of meshes formed by ribs, and the shapes of the meshes are hexagonal, trapezoidal and triangular.

4. The large-spacing pipe pile cushion structure according to claim 3 is characterized in that: The cross-section of the rib is rectangular.

5. The large-spacing pipe pile cushion structure according to claim 1 is characterized in that: The antioxidant strength retention rate, ultraviolet light resistance strength retention rate and acid and alkali solution resistance strength retention rate of the composite geogrid (5) are all ≥90%.

6. The large-spacing pipe pile mattress structure according to claim 1 is characterized in that: The high-strength geocell (6) comprises a plurality of cell sheets (61) and a plurality of connecting members (62), wherein the plurality of connecting members (62) are arranged in parallel, and the plurality of cell sheets (61) are respectively connected obliquely between adjacent connecting members (62).

7. The large-spacing pipe pile cushion structure according to claim 6 is characterized in that: The connecting member (62) comprises a plurality of U-shaped inserts, and the plurality of U-shaped inserts are connected to form a wave shape.

8. The large-spacing pipe pile cushion structure according to claim 7 is characterized in that: The cell sheet (61) is a rectangular parallelepiped, one end of the cell sheet (61) is connected to the U-shaped bottom of the U-shaped plug-in of the connecting piece (62), and the other end is connected to the open end of the U-shaped plug-in of the adjacent connecting piece (62).

9. The large-spacing pipe pile mattress structure according to claim 6 is characterized by: The height of the cell sheet (61) is 4-6 cm.

10. The construction method of the large-spacing pipe pile cushion structure according to any one of claims 1 to 9, characterized in that: Here are the steps: constructing a pile body (9), curing the pile body (9) to a specified strength and inspecting it to be qualified, and then constructing a pile cap; A layer of composite geogrid (5) is manually laid between the pile caps, and the first crushed stone cushion layer (21) is backfilled to the same level as the pile cap elevation; A layer of high-strength geocells (6) is manually laid on top of the first crushed stone cushion layer (21), and a second crushed stone cushion layer (31) is mechanically spread and leveled and compacted; A layer of composite geogrid (5) is manually laid on top of the second crushed stone cushion layer (31), and the third crushed stone cushion layer (41) is mechanically spread and leveled and compacted.

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