A special-shaped pile-mesh combined structure for reinforcing soft ground of water-rich land section

Abstract

The utility model discloses a kind of special-shaped pile-net combination structures for reinforcing soft weak ground base in water-rich section, the structure is composed of rigid long pile, special-shaped short pile, composite reinforced cushion and geogrid, multiple rigid long piles are arranged in soft weak ground base according to honeycomb form, pile top is contacted with composite reinforced cushion, special-shaped short pile is multistage inverted circular truncated cone shape, multiple special-shaped short piles are arranged at the center of each honeycomb structure, and composite reinforced cushion is composed of geogrid layer and macadam layer of different shape and size. The structure is based on the optimization special-shaped short pile structure form to promote bearing capacity, the combination form of long and short pile is strengthened, and the material characteristics and shape characteristics of granular grading macadam and flexible geogrid are used to make that combined pile-net structure has good deformation adaptability. While improving the bearing performance of overall structure, the use number of rigid long pile is effectively reduced, and construction cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of soft soil foundation reinforcement in civil engineering, specifically to an irregular pile-net combination structure for reinforcing soft soil foundations in water-rich areas. Background Technology

[0002] Pile foundations are a type of axial bearing structure widely used in soft soil strata. They are extensively applied in construction projects with high requirements for deformation control and bearing capacity. They achieve the structural requirements for bearing capacity of the underlying foundation and control of its own settlement deformation by directly transferring the overlying load to the surrounding soil or solid strata. This is especially true for soft soil foundations in water-rich areas, where the bearing capacity requirements are even higher. In water-rich areas, on the one hand, the soil moisture content is high, leading to weaker pile-soil interface interaction; on the other hand, the groundwater level is relatively high and fluctuates with climate changes, easily causing the shallow soil to undergo repeated wetting and drying processes, resulting in deterioration of soil mechanical properties and further weakening the pile-soil interface interaction. Therefore, constrained by bearing capacity requirements, existing axial bearing piles typically use reinforced concrete, with pile spacing selected according to existing specifications, often resulting in higher support costs.

[0003] In the process of realizing this invention, the inventors discovered at least the following problems in the prior art:

[0004] (1) Deterioration of bearing capacity of reinforced structures: When reinforcing soft foundations in water-rich areas, rigid long piles are prone to deterioration of the pile-soil interface, leading to a reduction in the side friction resistance of the pile, especially in shallow areas. Based on this, engineering projects often require rigid long piles to penetrate into solid bearing layers and be designed as end-bearing piles, often underestimating the contribution of pile side friction resistance to bearing capacity. In reality, the impact of water-rich foundations on rigid long piles goes beyond this. Due to the high water content and low density of soft foundation soil, significant plastic deformation is likely to occur. The soil around the pile has weak lateral deformation constraints on the rigid long pile. Once the long pile flexes due to excessive eccentric loads, the risk of pile breakage is high.

[0005] (2) The construction cost of the reinforced structure is relatively high: Rigid long piles rely on end bearing as the main bearing method. This requires both a rigid design of the pile top cushion layer to avoid excessive settlement of the soil due to pressure, and the arrangement of small piles at a large distance from the ground in the soft foundation. Therefore, the construction cost of the overall structure is inevitably increased.

[0006] Based on the above, it can be seen that the shallow pile-soil interface of the soft soil foundation in water-rich areas faces severe mechanical degradation. Common reinforcement structures not only have high construction costs, but may also have reduced bearing capacity in water-rich conditions, leading to excessive foundation settlement and deformation, which poses a serious threat to the service safety of the above-ground infrastructure. Utility Model Content

[0007] The purpose of this invention is to provide an irregular pile-net composite structure for reinforcing soft soil foundations in water-rich areas. This structure enhances the synergistic bearing capacity through the combination of long and short piles, and utilizes the material characteristics of granular graded crushed stone and flexible geogrid to give the composite pile-net structure good deformation adaptability. While improving the overall bearing performance of the structure, it effectively reduces the number of rigid long piles used and lowers construction costs.

[0008] To achieve the above objectives, this utility model provides an irregularly shaped pile-mesh composite structure for reinforcing soft soil foundations in water-rich areas. The structure includes multiple rigid long piles, multiple irregularly shaped short piles, a composite reinforced cushion layer, and a geogrid. The multiple rigid long piles are arranged in a honeycomb pattern within the soft soil foundation. The top of each rigid long pile contacts the bottom of the composite reinforced cushion layer, and the bottom of each rigid long pile extends below the local average annual groundwater level. The multiple irregularly shaped short piles are respectively arranged at the center of the multiple honeycomb structures formed by the multiple rigid long piles. The top of each irregularly shaped short pile also contacts the bottom of the composite reinforced cushion layer, and the bottom of each irregularly shaped short pile extends to the depth of the local average annual groundwater level. The cross-sectional diameter of the irregularly shaped short piles decreases progressively from top to bottom, forming multiple steps. The composite reinforced cushion layer includes a deformation regulating cushion layer and a transition cushion layer. The deformation regulating cushion layer is filled on the soft soil foundation, and the transition cushion layer is used to contact the engineering infrastructure structure. The geogrid includes vertical annular geogrids, flat circular geogrids, regular hexagonal geogrids, and flat rectangular geogrids. The vertical annular geogrids and the flat circular geogrids are multiple sets, the same number as the irregular short piles. The multiple sets of vertical annular geogrids are respectively arranged one-to-one with the sidewalls of the multiple irregular short piles. The multiple sets of flat circular geogrids are respectively arranged in the multiple irregular short piles. The regular hexagonal geogrids and the flat rectangular geogrids are respectively arranged in the deformation regulating cushion layer and the transition cushion layer.

[0009] Furthermore, each group of vertical annular geogrids is composed of multiple non-connected cylindrical geogrid units, the cross-sectional diameter of which decreases progressively from top to bottom; each group of flat circular geogrids includes multiple flat circular geogrid units, which are respectively disposed on the bottom wall of each step of the irregular short pile and the top wall of the top step; graded crushed stone is filled inside the vertical annular geogrid and between the upper and lower flat circular geogrid units.

[0010] Furthermore, the height of each of the multiple cylindrical geogrid units in each group of vertical annular geogrids corresponds one-to-one with the height of the multiple steps in each of the irregular short piles.

[0011] Furthermore, the deformation control cushion layer consists of at least one layer of hexagonal geogrid and at least one layer of graded crushed stone, which are filled in stages on the weak soil foundation. Each layer of hexagonal geogrid includes multiple overlapping hexagonal geogrid units. Each hexagonal geogrid unit covers one honeycomb structure, and the geometric center of each hexagonal geogrid unit is on the same vertical line as the center line of the honeycomb structure it covers.

[0012] Furthermore, adjacent hexagonal geogrid units overlap each other to form an overlap segment, the length of which is 100-200mm.

[0013] Furthermore, the transition cushion layer is composed of graded crushed stone and the flat rectangular geogrid. The graded crushed stone is filled on the deformation regulating cushion layer to form a primary graded crushed stone layer, and at least one layer of the flat rectangular geogrid is laid flat in the graded crushed stone layer.

[0014] Furthermore, the particle size of the graded crushed stone is no greater than 31.5 mm.

[0015] Furthermore, the slope of the line connecting the apex of the sidewall of the multi-stage steps of the irregular short pile is 30~40°, and the height of each step is 150~300mm.

[0016] Furthermore, the reinforcement treatment range formed by the multiple rigid long piles arranged in a honeycomb pattern should exceed 2000mm around the plane of the engineering infrastructure structure, and the range of the composite reinforced pad layer should not be less than the reinforcement treatment range of the multiple rigid long piles.

[0017] Furthermore, the geogrid is a biaxially oriented plastic geogrid, wherein the inner hole size of the geogrid is less than 30 mm, the geogrid tensile strength is greater than 80 kN / m, and the tensile strength at 2% elongation in the longitudinal direction is greater than 42 kN / m.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Optimized structural design enhances the bearing capacity of both long and short piles within the foundation in water-rich areas.

[0020] The secondary rotation and enlargement of the hole by the rotary drilling rig creates inclined textures on the sidewalls of the rigid long pile, forming a good mechanical interlock with the soil and increasing the contribution of the side friction resistance of the rigid long pile to its bearing capacity. Meanwhile, the multi-stage inverted frustum shape of the irregularly shaped short pile enhances its interaction with the surrounding soil as it moves downwards under load, improving the soil's support capacity and reducing settlement. Furthermore, the multi-stage inverted frustum shape of the irregularly shaped short pile causes its sidewalls to slope downwards. As the pile moves downwards, its inclined sidewalls compress the surrounding soil, promoting compaction and enhancing its bearing capacity.

[0021] 2. The combination of irregularly shaped short piles and rigid long piles enhances the synergistic bearing capacity.

[0022] The stepped structure of the irregularly shaped short piles creates a squeezing effect on the surrounding soil due to their inclined sidewalls, resulting in greater squeezing forces. The soil near the short piles transfers this squeezing pressure to the rigid long piles through stress diffusion, increasing the normal pressure acting on the sidewalls of the rigid long piles. This enhances the pile-soil interface interaction and increases the lateral skin friction on the sidewalls of the rigid long piles. Simultaneously, the honeycomb arrangement of the rigid long piles helps to evenly distribute the squeezing pressure around the central short pile, ensuring a uniform distribution of the squeezing pressure on the sidewalls of the rigid long piles. The symmetrically distributed sidewall pressure effectively constrains the rigid long piles, preventing lateral bending deformation and improving their bearing capacity. Conversely, the irregularly shaped short piles, subjected to uniform squeezing pressure, possess bearing capacity even after small deformations. Therefore, the synergistic effect between the irregularly shaped short piles and the rigid long piles enhances their combined bearing capacity.

[0023] 3. The composite pile-net structure has good deformation adaptability.

[0024] In water-rich conditions, when the superstructure load is transferred to the soft soil foundation, the composite reinforced cushion layer distributes the load to the tops of the rigid long piles and the irregularly shaped short piles. The hexagonal geogrid layer is adapted to the arrangement of the long and short pile holes. When the irregularly shaped short piles compress the soft foundation and cause settlement, they will exert a balancing tension towards the surrounding rigid long piles, inhibiting surface settlement. In addition, the irregularly shaped short piles can achieve local size control through the mutual displacement between the graded crushed stone filling inside, thereby applying a uniform compression effect to the surrounding soil and optimizing the pressure distribution of the surrounding soil and the pile-soil interface performance. The flexible geogrid material outside the irregularly shaped short piles maintains good elastic wrapping and restraint under the displacement adjustment of the graded crushed stone, allowing the crushed stone pile material to maintain its integrity while possessing deformation adaptability.

[0025] In summary, this invention provides an irregularly shaped pile-net composite structure for use in soft soil foundations in water-rich areas. Compared to existing technologies, it optimizes the structural form of irregularly shaped short piles to improve bearing capacity, enhances the synergistic bearing effect through the combination of long and short piles, and utilizes the material characteristics of granular graded crushed stone and flexible geogrid to give the composite pile-net structure good deformation adaptability. While improving the overall structural bearing performance, it effectively reduces the number of rigid long piles used, thus lowering project costs.

[0026] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a top view schematic diagram of the overall structure of the irregular pile-net combination structure of this utility model;

[0029] Figure 2 yes Figure 1 Schematic diagram of the MM cross-section structure of the irregular pile-mesh composite structure;

[0030] Figure 3 This is a top-view structural diagram of the honeycomb arrangement of long and short piles in the irregular pile-mesh composite structure of this utility model.

[0031] Figure 4 This is a top view schematic diagram of the overlapping construction of the regular hexagonal geogrid in the irregular pile-mesh combination structure of this utility model;

[0032] Figure 5 This is a top view schematic diagram of the construction of the composite reinforced cushion layer of the irregular pile-mesh combination structure of this utility model;

[0033] Figure 6 This is a cross-sectional schematic diagram of the irregular short pile structure of the irregular pile-net combination structure of this utility model;

[0034] Among them, 1-rigid long pile; 2-irregular short pile; 2a-step; 3-composite reinforced cushion layer; 3.1-deformation regulating cushion layer; 3.2-transition cushion layer; 4-geogrid; 4.1-vertical ring geogrid; 4.2-flat circular geogrid; 4.3-regular hexagonal geogrid; 4.4-flat rectangular geogrid; 5-graded crushed stone; 6-overlapping section; A-soft soil foundation; B-engineering infrastructure structure. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0036] Please see Figures 1 to 6 This embodiment provides an irregularly shaped pile-mesh composite structure for reinforcing soft soil foundations in water-rich areas, including multiple rigid long piles 1, multiple irregularly shaped short piles 2, a composite reinforced cushion layer 3, and a geogrid 4, as detailed below:

[0037] The rigid long pile 1 is a reinforced concrete structure. Under the secondary rotation and expansion action of the rotary drilling rig, its sidewall has inclined rough texture. Multiple rigid long piles 1 are arranged in a honeycomb pattern in the soft soil foundation A. The top of each rigid long pile 1 is in contact with the bottom of the composite reinforced cushion layer 3, and the bottom of each rigid long pile 1 extends below the local annual average groundwater level.

[0038] Multiple irregularly shaped short piles 2 are arranged one-to-one at the center of multiple honeycomb structures formed by multiple rigid long piles 1, extending within the soft soil foundation A to the depth of the local average annual groundwater level. The top of the irregularly shaped short piles 2 also contacts the bottom of the composite reinforced cushion layer 3. The cross-sectional diameter of the irregularly shaped short piles 2 gradually decreases from top to bottom, forming multiple steps 2a. Specifically, the irregularly shaped short piles 2 are composed of multiple cylindrical structures of different diameters, each cylindrical structure being a step 2a, with the cross-sectional diameter of the multiple steps 2a gradually decreasing from top to bottom. The irregularly shaped short piles 2 can convert part of the vertical load acting on the short piles into a horizontal load acting on the rigid long piles 1, effectively enhancing the flexural stability of the rigid long piles 1 and the pile-soil interface interaction. Under the same bearing conditions, the use of reinforced concrete is effectively reduced, lowering the construction cost of the reinforced structure.

[0039] To fully utilize the soil displacement effect, the slope of the line connecting the apexes of the sidewalls of the multi-stage steps 2a of the irregular short pile 2 (located within the same vertical section) should be controlled within the range of 30-40°. Simultaneously, considering the integrity of the geogrid 4 enclosure, the height of each step should be controlled within the range of 150-300mm. During the construction of the irregular short pile 2, a rotary drilling rig with an enlarging head function is used to excavate multi-stage steps with progressively decreasing diameters from top to bottom on the soft soil foundation A surface to prevent soil debris from falling to the bottom, and then the vertical annular geogrid 4.1 is placed tightly inside.

[0040] Depending on their intended use, the geogrid 4 includes vertical annular geogrids 4.1, flat circular geogrids 4.2, regular hexagonal geogrids 4.3, and flat rectangular geogrids 4.4. The vertical annular geogrids 4.1 and flat circular geogrids 4.2 are arranged in multiple sets, the same number as the irregular short piles 2. Each set of vertical annular geogrids 4.1 corresponds one-to-one with the sidewalls of the irregular short piles 2, and each set of flat circular geogrids 4.2 is disposed within the irregular short piles 2. Each set of vertical annular geogrids 4.1 consists of multiple non-connected cylindrical geogrid units. Corresponding to the structural shape of the irregular short piles 2, the cross-sectional diameter of the multiple cylindrical geogrid units decreases progressively from top to bottom. Each set of flat circular geogrids 4.2 includes multiple flat circular geogrid units, which are disposed on the bottom wall of each step of the irregular short pile 2 and the top wall of the topmost step. A set of vertical annular geogrids 4.1 is filled with graded crushed stone 5 between two upper and lower flat circular geogrid units. Specifically, the irregular short pile 2 is composed of vertical annular geogrids 4.1, flat circular geogrids 4.2, and graded crushed stone 5 filling the spaces between the geogrids. The height of the multiple cylindrical geogrid units in each set of vertical annular geogrids 4.1 corresponds one-to-one with the height of the multiple steps 2a in each irregular short pile 2. In this structural setup, the geogrid 4 is a biaxially oriented plastic geogrid with an inner hole size of less than 30 mm, a tensile strength greater than 80 kN / m, and a tensile strength greater than 42 kN / m at 2% elongation in the longitudinal direction.

[0041] The composite reinforced cushion layer 3 consists of a deformation-regulating cushion layer 3.1 arranged at the bottom and a transition cushion layer 3.2 arranged at the top. The bottom of the deformation-regulating cushion layer 3.1 is in contact with the rigid long piles 1, and the top of the transition cushion layer 3.2 is in contact with the engineering infrastructure structure B. The deformation-regulating cushion layer 3.1 consists of at least one layer of regular hexagonal geogrid 4.3 and at least one layer of graded crushed stone 5. Each layer of regular hexagonal geogrid 4.3 includes multiple overlapping regular hexagonal geogrid units. The six corners of each regular hexagonal geogrid unit are covered by a honeycomb structure formed by multiple rigid long piles 1, and the geometric center of each regular hexagonal geogrid unit is on the same vertical line as the center line of the honeycomb structure it covers. The multiple regular hexagonal geogrid units arranged in the same layer overlap each other, and the length of the overlap section 6 should preferably be controlled within 100-200mm. The multiple overlapping regular hexagonal geogrid units constitute an integral regular hexagonal geogrid layer with adaptive expansion and contraction function. At least one layer of hexagonal geogrid 4.3 and at least one layer of graded crushed stone 5 are laid in stages on the soft soil foundation A. A transition layer 3.2 is laid on top of the deformation control layer 3.1, consisting of graded crushed stone 5 and a flat rectangular geogrid 4.4. The graded crushed stone 5 is laid on the deformation control layer 3.1 to form a primary graded crushed stone layer, in which at least one layer of flat rectangular geogrid 4.4 is laid flat. The particle size of the graded crushed stone 5 is no greater than 31.5 mm.

[0042] In one specific implementation, the reinforcement treatment range formed by multiple rigid long piles 1 arranged in a honeycomb pattern should extend at least 2000 mm beyond the plane of the engineering infrastructure structure B, and the range of the composite reinforced pad layer 3 should not be less than the reinforcement treatment range of the rigid long piles 1.

[0043] The construction method of the above-mentioned irregular pile-mesh composite structure for reinforcing soft soil foundations in water-rich areas according to this utility model generally includes the following steps:

[0044] S1. Level the surface of the soft soil foundation A, remove debris, distribute the rigid long piles 1 in a honeycomb pattern on the foundation surface, and arrange the irregular short piles 2 at the center of each honeycomb structure formed by the rigid long piles 1 to determine the overall treatment range and construction points of the composite pile-net structure.

[0045] S2. Due to the significant soil displacement effect exhibited during the construction of the irregularly shaped short pile 2, the construction process should proceed as follows: first the rigid long pile 1, then the irregularly shaped short pile 2; first the center point, then the outer ring points; first the underground structure, then the above-ground structure. Among these:

[0046] (1) For rigid long pile 1, the rotary drilling rig should drill the hole to below the local average annual groundwater level. The drilling of the main body of the pile should be completed during the first rotary drilling process, and the hole should be enlarged by rotation during the second rotary drilling process, forming inclined rotational patterns on the sidewall of the hole. Remove the sediment generated during the second rotary drilling process to ensure that there is no loose soft soil at the bottom of the pile before pouring. After the pouring is completed, the sidewall of rigid long pile 1 should show a clear interface with the soil, and the construction of the remaining rigid long pile 1 should continue.

[0047] (2) For the irregular short pile 2, a rotary drilling rig with an enlarging head function should be used to meet the requirement of gradually changing diameter of the circular cross-section of the multi-stage steps 2a. The center point should be selected for construction to fully utilize the soil squeezing effect. To prevent soil from falling to the bottom, multi-stage steps with progressively decreasing diameter should be drilled sequentially from top to bottom and from wide to narrow. After the rotary drilling is completed, the vertical annular geogrid units should be placed tightly against the bottom and side steps of the multi-stage steps. Then, graded crushed stone 5 should be gradually filled into the vertical annular geogrid units and fully compacted. Simultaneously, flat circular geogrid units should be placed at each inverted frustum step, filling step by step until flush with the foundation surface, and then the construction of the remaining irregular short piles 2 should be completed.

[0048] S3. Constructing the composite reinforced cushion layer 3. First, lay a hexagonal geogrid layer on the foundation surface, ensuring that the geometric center of each hexagonal geogrid 4.3 unit is aligned with the centerline of the multiple irregular short piles 2 (i.e., the center of the honeycomb structure) on the same vertical line. The six corners of the hexagonal geogrid unit are covered by the honeycomb structure formed by the rigid long piles 1. Multiple hexagonal geogrid units in the same layer overlap each other, with the overlap length preferably controlled between 100-200mm. Next, fill the hexagonal geogrid layer with graded crushed stone, and then compact the graded crushed stone 5 in layers. Depending on the project requirements, select to lay one or more hexagonal geogrid layers and crushed stone layers to complete the construction of the deformation control cushion layer 3.1. Then, construct the transition cushion layer 3.2 on top of the deformation control cushion layer 3.1. Lay a layer of flat rectangular geogrids, ensuring a certain length of overlap between adjacent flat rectangular geogrids 4.4. Then, fill the layer with graded crushed stone, and compact the graded crushed stone 5 in layers. Depending on the project requirements, select to lay one or more layers of flat rectangular geogrids and crushed stone to complete the construction of the transition cushion layer 3.2.

[0049] S4. After completing the reinforcement treatment of the weak soil foundation A, conduct an in-situ load test on the composite reinforced cushion layer 3 to test whether the foundation bearing capacity meets the requirements. After the test meets the standards or is optimized to meet the standards, proceed with the construction of the superstructure infrastructure structure B.

[0050] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An irregularly shaped pile-mesh composite structure for reinforcing weak soil foundations in water-rich areas, characterized in that, The structure includes multiple rigid long piles (1), multiple irregular short piles (2), a composite reinforced cushion layer (3), and a geogrid (4). The multiple rigid long piles (1) are arranged in a honeycomb pattern within the soft soil foundation (A). The top of each rigid long pile (1) contacts the bottom of the composite reinforced cushion layer (3), and the bottom of each rigid long pile (1) extends below the local average annual groundwater level. The multiple irregular short piles (2) are respectively arranged at the center of multiple honeycomb structures formed by the multiple rigid long piles (1). The top of each irregular short pile (2) also contacts the bottom of the composite reinforced cushion layer (3), and the bottom of each irregular short pile (2) extends to the depth of the local average annual groundwater level. The cross-sectional diameter of the irregular short piles (2) decreases from top to bottom, forming multiple steps (2a). The composite reinforced cushion layer (3) includes a deformation control cushion layer (3.1) and a transition cushion layer (3.2). 1) The transition cushion layer (3.2) is filled on a soft soil foundation (A) and is used to contact the engineering infrastructure structure (B); the geogrid (4) includes a vertical ring geogrid (4.1), a flat circular geogrid (4.2), a regular hexagonal geogrid (4.3) and a flat rectangular geogrid (4.4). The vertical ring geogrid (4.1) and the flat circular geogrid (4.2) are multiple sets, the same number as the irregular short piles (2). The multiple sets of vertical ring geogrids (4.1) are respectively set one-to-one with the sidewalls of the multiple irregular short piles (2). The multiple sets of flat circular geogrids (4.2) are respectively set in the multiple irregular short piles (2). The regular hexagonal geogrid (4.3) and the flat rectangular geogrid (4.4) are respectively set in the deformation control cushion layer (3.1) and the transition cushion layer (3.2).

2. The irregular pile-net composite structure according to claim 1, characterized in that, Each group of vertical annular geogrids (4.1) consists of multiple non-connected cylindrical geogrid units, the cross-sectional diameter of which decreases from top to bottom; each group of flat circular geogrids (4.2) includes multiple flat circular geogrid units with different diameters, and the multiple flat circular geogrid units in the same group are respectively set on the bottom wall of the multi-level steps of the irregular short pile (2) and the top wall of the topmost step; the vertical annular geogrids (4.1) is filled with graded crushed stone (5) between the upper and lower flat circular geogrid units.

3. The irregular pile-net composite structure according to claim 2, characterized in that, The height of each cylindrical geogrid unit of the vertical annular geogrid (4.1) corresponds one-to-one with the height of the multi-level steps (2a) in each irregular short pile (2).

4. The irregular pile-net composite structure according to claim 1, characterized in that, The deformation control cushion layer (3.1) consists of at least one layer of the regular hexagonal geogrid (4.3) and at least one layer of graded crushed stone (5) filled in stages on the soft soil foundation (A). Each layer of the regular hexagonal geogrid (4.3) includes multiple overlapping regular hexagonal geogrid units. Each regular hexagonal geogrid unit covers one honeycomb structure, and the geometric center of each regular hexagonal geogrid unit is on the same vertical line as the center line of the honeycomb structure it covers.

5. The irregular pile-net composite structure according to claim 4, characterized in that, Adjacent hexagonal geogrid units overlap to form an overlap section (6), the length of which is 100-200mm.

6. The irregular pile-net composite structure according to claim 4, characterized in that, The transition cushion layer (3.2) is composed of graded crushed stone (5) and the flat rectangular geogrid (4.4). The graded crushed stone (5) is filled on the deformation regulating cushion layer (3.1) to form a primary graded crushed stone layer. At least one layer of the flat rectangular geogrid (4.4) is laid flat in the graded crushed stone layer.

7. The irregular pile-net composite structure according to any one of claims 2-6, characterized in that, The particle size of the graded crushed stone (5) is no greater than 31.5 mm.

8. The irregular pile-net composite structure according to claim 1, characterized in that, The slope of the line connecting the apex of the sidewall of the multi-level steps (2a) of the irregular short pile (2) is 30~40°, and the height of each step is 150~300mm.

9. The irregular pile-net composite structure according to claim 1, characterized in that, The reinforcement treatment range formed by the multiple rigid long piles (1) arranged in a honeycomb pattern should exceed 2000mm around the plane of the engineering infrastructure structure (B), and the range of the composite reinforced cushion layer (3) should not be less than the reinforcement treatment range of the multiple rigid long piles (1).

10. The irregular pile-net composite structure according to claim 1, characterized in that, The geogrid (4) is a biaxial tensile plastic geogrid. The inner hole size of the geogrid (4) is less than 30 mm, the tensile strength of the geogrid is greater than 80 kN / m, and the tensile strength at 2% elongation in the longitudinal direction is greater than 42 kN / m.

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