Composite roadbed based on rigid piles

Abstract

According to the composite roadbed based on the rigid piles, the rigid piles are buried in the soft soil layers below the common soft soil roadbed and the immersed soft soil roadbed, and the pile caps are arranged on the sand cushion layers of the soft soil roadbed and are connected with the rigid piles, so that the roadbed and the foundation form a whole, and upper loads are effectively dispersed and transmitted to the deeper soil layers; the overall bearing capacity and stability of the foundation are improved, and the condition of foundation settlement caused by too high water content of the soft soil layer is effectively avoided; meanwhile, the permeable filler layer is arranged between the immersed soft soil roadbed and the soft soil layer, so that the overall strength and stability of the immersed soft soil roadbed can be further enhanced, and the immersed soft soil roadbed and a common soft soil roadbed are prevented from uneven settlement; and the seepage resistance of the soil layer can be effectively reduced by utilizing the good water permeability of the filler, so that water in the soaked soft soil roadbed can be discharged more smoothly, and the condition of sedimentation caused by untimely water discharge of the soaked soft soil roadbed can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of roadbed foundation reinforcement technology, and in particular to a composite roadbed based on rigid piles. Background Technology

[0002] For foundations near water bodies, the soil moisture content is typically high due to prolonged immersion, which reduces the contact force between soil particles and consequently decreases the soil's stiffness and shear strength. High moisture content also tends to cause the soil to become sticky and pasty, making it easily infiltrated by water. Under load, it is prone to compression deformation. In addition, the poor permeability of soft soil makes it difficult for water to drain, exacerbating soil instability.

[0003] Therefore, roadbeds built on soft soil foundations often suffer from insufficient bearing capacity, leading to settlement and deformation along with the foundation. In particular, the side of the roadbed closer to the water body experiences more severe waterlogging than the side further away, resulting in different bearing capacities between the two sides of the roadbed and the foundation. Under excessive superload, this can cause uneven settlement of the roadbed along with the foundation, ultimately damaging the road and affecting its performance and lifespan. Therefore, it is necessary to modify waterlogged roadbeds by providing a composite roadbed based on rigid piles. Utility Model Content

[0004] In view of the technical problems in the existing soft soil subgrade, the different water content on the near and far sides of the ground causes the subgrade to easily deform with the ground settlement, and the subgrade on the near and far sides of the ground is prone to uneven settlement, this utility model provides a composite subgrade based on rigid piles.

[0005] A composite roadbed based on rigid piles includes a general soft soil roadbed filled above the water-depleted side of a soft soil layer, a water-soaked soft soil roadbed filled above the water-near side of the soft soil layer, and a plurality of rigid piles uniformly arrayed and embedded in the soft soil layer; the general soft soil roadbed and the water-soaked soft soil roadbed are integrally formed, the top surfaces of the general soft soil roadbed and the water-soaked soft soil roadbed are flush, and both the top surfaces of the general soft soil roadbed and the water-soaked soft soil roadbed are provided with a pavement structure layer; a channel for promoting water immersion is filled between the water-soaked soft soil roadbed and the soft soil layer. The permeable filler layer for drainage of soft soil subgrade; both the general soft soil subgrade and the waterlogged soft soil subgrade include a sand cushion layer, a crushed stone cushion layer and a first fill layer sequentially constructed away from the soft soil layer; and a bidirectional geogrid layer is laid at the bottom and top of the crushed stone cushion layer; several pile caps are evenly distributed in the sand cushion layer, the pile heads of the rigid piles are fixedly connected to the pile caps, and the pile bottoms of the rigid piles under the general soft soil subgrade pass through the soft soil layer, while the pile bottoms of the rigid piles under the waterlogged soft soil subgrade sequentially pass through the permeable filler layer and the soft soil layer.

[0006] Preferably, the rigid pile is a plain concrete pile; the pile cap includes a precast frame made of steel bars, a concrete layer enclosing the precast frame, and a second skeleton vertically connected to the bottom of the precast frame; the precast frame includes a first skeleton arranged horizontally with the sand cushion layer and an outer ring skeleton arranged in a ring around the first skeleton; and the second skeleton is connected to the middle of the first skeleton, and the other side of the second skeleton is anchored in the pile head of the plain concrete pile.

[0007] Furthermore, the permeable filler layer is made of one or more of the following: rubble, crushed stone, medium-coarse sand, gravel, and strongly weathered rock soil.

[0008] Preferably, the rigid pile is a pipe pile; the pile cap includes a precast frame made of steel bars, a concrete layer enclosing the precast frame, and a support plate. The precast frame includes a first skeleton horizontally arranged with the sand cushion layer, an outer ring skeleton arranged in a ring around the first skeleton, and a second skeleton vertically connected to the bottom of the first skeleton. The support plate is arranged at the bottom of the second skeleton. The second skeleton is connected to the bottom of the first skeleton, and the bottom of the second skeleton is embedded in the pile head of the pipe pile.

[0009] Furthermore, the pipe pile is a prestressed PHC pile, and the outer diameter of the pipe pile is 40cm, and the wall thickness is not less than 8cm; the support plate is made of C30 reinforced concrete.

[0010] Furthermore, the permeable fill layer includes a second fill layer and a permeable base layer constructed along the direction away from the waterlogged soft soil subgrade, and the permeable base layer is constructed by a mixture of one or more of the following: rubble, crushed stone, medium-coarse sand, gravel, and strongly weathered rocky soil.

[0011] Furthermore, the bidirectional geogrid layer comprises several bidirectional geogrids that overlap sequentially. The width of the bidirectional geogrid is not less than 2m, the overlap length is not less than 30cm, and each bidirectional geogrid is fixed by several U-shaped nails.

[0012] Furthermore, both the side of the general soft soil subgrade away from the waterlogged soft soil subgrade and the side of the waterlogged soft soil subgrade away from the general soft soil subgrade form a slope, and the sand cushion layer extends beyond the corresponding slope to form a sand and gravel extension; a drainage pipe and a filter layer located at the inlet of the drainage pipe are provided in the sand and gravel extension; the filter layer includes several gravel and a filter geotextile wrapped around the gravel; and a clay seal layer is provided on the sand and gravel extension.

[0013] Furthermore, the reverse filter geotextile is a polypropylene needle-punched nonwoven geotextile with a unit area mass of 300 g / m², a thickness of not less than 2.4 mm, a width of not less than 3 m, a longitudinal and transverse tensile strength of not less than 9.5 kN / m, a longitudinal and transverse tensile elongation of not more than 50%, a vertical permeability coefficient of not less than 0.05 cm / s, a longitudinal and transverse tear strength of not less than 0.24 kN, and a CBR puncture strength of not less than 1.5 kN.

[0014] Furthermore, a drainage ditch is provided on the side of the general soft soil roadbed away from the waterlogged soft soil roadbed and on the side of the waterlogged soft soil roadbed away from the general soft soil roadbed, and the drainage ditch is connected to the corresponding drainage pipe.

[0015] The beneficial effects of this utility model are as follows: This utility model provides a composite roadbed based on rigid piles. By embedding rigid piles in the soft soil layer below general soft soil roadbeds and waterlogged soft soil roadbeds, and setting pile caps to connect the rigid piles in the sand cushion layer, the roadbed and foundation form an integral whole. This effectively disperses and transfers the upper load to the deeper soil layer, improving the overall bearing capacity and stability of the foundation, and effectively avoiding foundation settlement caused by excessive water content in the soft soil layer. Simultaneously, the permeable filler layer set between the waterlogged soft soil roadbed and the soft soil layer further enhances the overall strength and stability of the waterlogged soft soil roadbed, preventing uneven settlement between the waterlogged soft soil roadbed and general soft soil roadbeds. It also effectively reduces the seepage resistance of the soil layer by utilizing the good permeability of the filler, allowing water in the waterlogged soft soil roadbed to drain more smoothly, avoiding settlement caused by untimely drainage. Furthermore, by laying bidirectional geogrid layers at the bottom and top of the crushed stone cushion layer, the integrity and stability of the roadbed are further enhanced, extending the service life of the roadbed. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a composite roadbed based on rigid piles provided in Example 1;

[0017] Figure 2 for Figure 1 A schematic diagram of the structure of part A;

[0018] Figure 3 This is a schematic diagram of the connection structure between the pile cap and the plain concrete pile in Example 1;

[0019] Figure 4 This is a schematic diagram of a composite roadbed based on rigid piles provided in Example 2;

[0020] Figure 5 This is a schematic diagram of the connection structure between the pile cap and the plain concrete pile provided in Example 2;

[0021] Figure 6 This is a schematic diagram of the rigid pile distribution structure of this utility model.

[0022] Attached Figure Labels

[0023] 1. Soft soil layer; 2. General soft soil subgrade; 21. Sand cushion layer; 22. Crushed stone cushion layer; 211. Sand and gravel extension; 23. First fill layer; 3. Waterlogged soft soil subgrade; 4. Rigid pile; 5. Pavement structure layer; 6. Permeable fill layer; 7. Bidirectional geogrid layer; 8. Pile cap; 81, 801. Precast frame; 811, 8011. First skeleton; 812, 8012. Outer ring skeleton; 82, 802. Concrete layer; 83, 8013. Second skeleton; 803. Support plate; 9. Drainage pipe; 10. Filter layer; 11. Clay seal layer; 12. Drainage ditch. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] refer to Figure 1 and Figure 6 As shown, a composite roadbed based on rigid piles includes a general soft soil roadbed 2 filled above the water-outside of a soft soil layer 1, a water-soaked soft soil roadbed 3 filled above the water-nearside of the soft soil layer 1, and a plurality of rigid piles 4 uniformly arrayed and buried within the soft soil layer 1. The water-soaked soft soil roadbed 3 is located close to the water body, resulting in a high water content in both it and the underlying soft soil layer 1, making it prone to settlement, and exhibiting uneven settlement compared to the general soft soil roadbed 2.

[0027] Specifically, the general soft soil roadbed 2 and the waterlogged soft soil roadbed 3 are integrally formed. The top surface of the general soft soil roadbed 2 and the top surface of the waterlogged soft soil roadbed 3 are flush. Both the top surface of the general soft soil roadbed 2 and the top surface of the waterlogged soft soil roadbed 3 are provided with a road surface structure layer 5, which provides stable and flat road surface conditions for vehicles to pass through and ensures the comfort of driving on the road above the roadbed.

[0028] A permeable filler layer 6 is constructed between the submerged soft soil subgrade 3 and the soft soil layer 1 to promote drainage of the submerged soft soil subgrade 3. In this embodiment, the permeable filler layer 6 is made of one or more of the following: rubble, crushed stone, medium-coarse sand, gravel, and strongly weathered rock soil. The permeable filler layer 6 itself has a certain strength and rigidity. When combined with the soft soil subgrade, it can form a composite subgrade, enhancing the overall strength and stability of the subgrade. Furthermore, the permeable filler layer 6 is composed of materials with good permeability, such as rubble, crushed stone, medium-coarse sand, gravel, and strongly weathered rock soil. This effectively reduces the seepage resistance of the soil layer, allowing water in the submerged soft soil subgrade 3 to drain more smoothly. At the same time, because the permeable filler layer 6 promotes drainage and consolidation of the soft soil subgrade, the settlement of the subgrade during construction and operation is significantly reduced, which helps to extend the service life of the road and avoid road surface cracking, collapse, and other defects caused by uneven settlement.

[0029] Both the general soft soil subgrade 2 and the waterlogged soft soil subgrade 3 include a sand cushion layer 21, a crushed stone cushion layer 22, and a first fill layer 23 sequentially constructed away from the soft soil layer 1, forming a good stress dispersion system. In this embodiment, the thickness of the crushed stone cushion layer 22 is 30cm, and the crushed stone used has a particle size of not less than 40mm.

[0030] Due to its good permeability and large particle size, the crushed stone cushion layer 22 can effectively disperse the load on the upper part of the subgrade and reduce the pressure on the underlying soft soil layer, thereby improving the bearing capacity of the entire subgrade. At the same time, the large pore structure of the crushed stone cushion layer helps to drain water quickly, promotes the natural consolidation process of the soft soil layer 1, and reduces subgrade settlement and instability caused by water accumulation.

[0031] The bottom and top of the crushed stone cushion layer 22 are both covered with a bidirectional geogrid layer 7; the bidirectional geogrid layer 7 includes several bidirectional geogrids that overlap sequentially, the width of the bidirectional geogrid is not less than 2m, the overlap length is not less than 30cm, and each bidirectional geogrid is fixed by several U-shaped nails.

[0032] By laying bidirectional geogrid layers 7 at the bottom and top of the crushed stone cushion layer 11, the integrity and stability of the subgrade are further enhanced. The bidirectional geogrid, through its high tensile strength and friction with the crushed stone cushion layer 11, can effectively limit the lateral displacement of the crushed stone cushion layer 11 and other soil layers, thus preventing the subgrade from becoming unstable.

[0033] In this embodiment, the geogrid is a one-time stretched polypropylene biaxial pleated geogrid, which must not be welded without nodes. The longitudinal and transverse ultimate tensile strength per meter is not less than 50kN / m, the elongation at the nominal tensile strength in the longitudinal and transverse directions is not greater than 13%, the tensile force at 2% elongation in the longitudinal and transverse directions is not less than 17.5kN / m, and the tensile force at 5% elongation is not less than 35kN / m.

[0034] A plurality of pile caps 8 are evenly distributed within the sand cushion layer 21. The pile heads of the rigid piles 4 are fixedly connected to the pile caps 8. The bottom of the rigid piles 4 below the general soft soil subgrade 2 passes through the soft soil layer 1, and the bottom of the rigid piles 4 below the water-soaked soft soil subgrade 3 passes through the permeable fill layer 5 and the soft soil layer 1 in sequence. In this embodiment, the pile spacing of the rigid piles 4 is S. When S≤1.4m, pile caps 8 are not required; when 1.4m<S<2m, the size of the pile caps 8 is 1.0m×1.0m×0.35m; when S≥2m, the size of the pile caps 8 is 1.2m×1.2m×0.35m.

[0035] The pile cap 8 tightly connects the rigid pile 4 with the sand cushion layer 21, making the roadbed and the foundation a whole, which improves the overall bearing capacity and stability of the foundation; at the same time, the high strength and high rigidity of the rigid pile 4 effectively disperses and transfers the upper load to the deeper soil layer, thereby reducing the settlement and uneven settlement of the foundation.

[0036] Specifically, refer to Figure 1 and Figure 3 As shown, the rigid pile 4 is a plain concrete pile; the pile cap 8 includes a precast frame 81 made of steel bars, a concrete layer 82 enclosing the precast frame 81, and a second skeleton 83 vertically connected to the bottom of the precast frame 81; the precast frame 81 includes a first skeleton 811 horizontally arranged with the sand cushion layer 21 and an outer ring skeleton 812 arranged in a ring around the first skeleton 811; and the second skeleton 83 is connected to the middle of the first skeleton 811, and the other side of the second skeleton 83 is anchored in the pile head of the plain concrete pile. In this embodiment, the cross-sectional diameter of the plain concrete pile is 40cm, and the cement used in the pile body is ordinary Portland cement of grade 42.5R or higher.

[0037] refer to Figure 1 and Figure 2 As shown, both the side of the general soft soil subgrade 2 away from the waterlogged soft soil subgrade 3 and the side of the waterlogged soft soil subgrade 3 away from the general soft soil subgrade 2 form slopes. The crushed stone cushion layer 22 extends beyond the corresponding slope and forms a gravel extension 211. A drainage pipe 9 and a filter layer 10 are provided inside the gravel extension 211. The filter layer 10 includes several crushed stones and a filter geotextile wrapped around the crushed stones. A clay seal layer 11 is provided on each gravel extension 211. In this embodiment, the drainage pipe 9 is a PVC pipe with a diameter of 11cm and a length of 110cm. The dimensions of the filter layer 10 are 30cm × 30cm × 30cm. The thickness of the clay seal layer 11 is 30cm.

[0038] The drainage pipe 9 within the gravel extension 211 provides an effective drainage channel for accumulated water within the roadbed, reducing moisture buildup and accelerating the drainage and consolidation process. The filter layer 10, composed of crushed stone and geotextile, effectively prevents soil and fine particles from entering the drainage pipe 9, ensuring unobstructed drainage. The clay seal layer 11 prevents rainwater and other water sources from directly infiltrating into the gravel extension 211, maintaining the stability of its internal structure and reducing external water erosion of the roadbed.

[0039] The geotextile is a polypropylene needle-punched nonwoven geotextile with a unit area mass of 300 g / m², a thickness of not less than 2.4 mm, a width of not less than 3 m, a longitudinal and transverse tensile strength of not less than 9.5 kN / m, a longitudinal and transverse tensile elongation of not more than 50%, a vertical permeability coefficient of not less than 0.05 cm / s, a longitudinal and transverse tear strength of not less than 0.24 kN, and a CBR puncture strength of not less than 1.5 kN.

[0040] A drainage ditch 12 is provided on the side of the general soft soil subgrade 2 away from the waterlogged soft soil subgrade 3 and on the side of the waterlogged soft soil subgrade 3 away from the general soft soil subgrade 2, respectively. The drainage ditch 12 is connected to the corresponding drain pipe 9. The drainage ditch 12 can effectively collect and drain water accumulated on the subgrade and pavement structure layer, prevent water from remaining for a long time, and reduce problems such as subgrade softening and settlement caused by water infiltration.

[0041] Example 2

[0042] refer to Figure 4 and Figure 5 As shown, compared with Example 1, the difference between Example 2 and Example 1 lies in that the rigid pile 4 is a pipe pile; the pile cap 8 includes a precast frame 801 made of steel bars, a concrete layer 802 enclosing the precast frame 801, and a support plate 803. The precast frame 801 includes a first skeleton 8011 horizontally arranged with the sand cushion layer 21, an outer ring skeleton 8012 arranged in a ring around the first skeleton 8011, and a second skeleton 8013 vertically connected to the bottom of the first skeleton 8011; the support plate 803 is disposed at the bottom of the second skeleton 8013; the second skeleton 8013 is connected to the bottom of the first skeleton 8011, and the bottom of the second skeleton 8013 is embedded in the pile head of the pipe pile. The bottom of the first skeleton 8011, the support plate 803, and the inner wall of the second skeleton 8013 form a casting space, and C30 concrete is poured therein.

[0043] The pipe pile is a prestressed PHC pile, with an outer diameter of 40cm and a wall thickness of not less than 8cm; the support plate 803 is made of C30 reinforced concrete.

[0044] The permeable fill layer 6 includes a second fill layer 61 constructed along the direction away from the waterlogged soft soil subgrade 3 and a permeable base layer 62. The permeable base layer 62 is constructed from one or more of the following materials: rubble, crushed stone, medium-coarse sand, gravel, and strongly weathered rocky soil. The permeable base layer 62 stabilizes the entire structure of the waterlogged soft soil subgrade 3. The materials used in the permeable base layer 62 have high porosity and good permeability, effectively allowing rainwater or groundwater to drain quickly and reducing water accumulation inside the subgrade.

[0045] The geogrid is a biaxial polypropylene geogrid (GSL50 / PP), with a longitudinal and transverse ultimate tensile strength of not less than 50kN / m per linear meter, an elongation of not more than 13% at the nominal longitudinal and transverse tensile strength, a tensile force of not less than 17kN / m at 2% elongation in the longitudinal and transverse directions, and a tensile force of not less than 34kN / m at 5% elongation.

[0046] The preferred embodiments of this utility model disclosed above are merely illustrative of the present utility model and do not limit the utility model to the specific implementations described. Obviously, other modifications and variations can be made based on the content of this specification. The embodiments selected and specifically described in this specification are intended to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it. They are not intended to limit the utility model, and any simple modifications to this utility model fall within the protection scope of this utility model.

Claims

1. A composite roadbed based on rigid piles, characterized in that, This includes general soft soil roadbeds filled above the water-far side of the soft soil layer, waterlogged soft soil roadbeds filled above the water-near side of the soft soil layer, and several rigid piles uniformly arrayed and buried in the soft soil layer. The general soft soil subgrade and the waterlogged soft soil subgrade are integrally formed and constructed. The top surface of the general soft soil subgrade and the top surface of the waterlogged soft soil subgrade are flush, and both the top surface of the general soft soil subgrade and the top surface of the waterlogged soft soil subgrade are provided with a pavement structure layer. A permeable filler layer is constructed between the submerged soft soil roadbed and the soft soil layer to promote drainage of the submerged soft soil roadbed. Both the general soft soil subgrade and the waterlogged soft soil subgrade include a sand cushion layer, a crushed stone cushion layer and a first fill layer that are sequentially filled along the path away from the soft soil layer; and a bidirectional geogrid layer is laid at the bottom and top of the crushed stone cushion layer. Several pile caps are evenly distributed within the sand cushion layer. The pile head of the rigid pile is fixedly connected to the pile cap. The bottom of the rigid pile under the general soft soil subgrade passes through the soft soil layer. The bottom of the rigid pile under the water-soaked soft soil subgrade passes through the permeable fill layer and the soft soil layer in sequence.

2. A composite roadbed based on rigid piles according to claim 1, characterized in that, The rigid pile is a plain concrete pile; the pile cap includes a precast frame made of steel bars, a concrete layer enclosing the precast frame, and a second skeleton vertically connected to the bottom of the precast frame; the precast frame includes a first skeleton horizontally arranged with the sand cushion layer and an outer ring skeleton arranged in a ring around the first skeleton; and the second skeleton is connected to the middle of the first skeleton, and the other side of the second skeleton is anchored in the pile head of the plain concrete pile.

3. A composite roadbed based on rigid piles according to claim 1, characterized in that, The rigid pile is a pipe pile; the pile cap includes a precast frame made of steel bars, a concrete layer enclosing the precast frame, and a support plate. The precast frame includes a first skeleton horizontally arranged with the sand cushion layer, an outer ring skeleton arranged in a ring around the first skeleton, and a second skeleton vertically connected to the bottom of the first skeleton. The support plate is arranged at the bottom of the second skeleton. The second skeleton is connected to the bottom of the first skeleton, and the bottom of the second skeleton is embedded in the pile head of the pipe pile.

4. A composite roadbed based on rigid piles according to claim 3, characterized in that, The pipe pile is a prestressed PHC pile, with an outer diameter of 40cm and a wall thickness of not less than 8cm; the support plate is made of C30 reinforced concrete.

5. A composite roadbed based on rigid piles according to claim 3, characterized in that, The permeable fill layer includes a second fill layer and a permeable base layer constructed along the direction away from the waterlogged soft soil subgrade, and the permeable base layer is made of one or more of the following: rubble, crushed stone, medium and coarse sand, gravel, and strongly weathered rock soil.

6. A composite roadbed based on rigid piles according to claim 1, characterized in that, The bidirectional geogrid layer comprises several bidirectional geogrids that overlap sequentially. The width of the bidirectional geogrid is not less than 2m, the overlap length is not less than 30cm, and each bidirectional geogrid is fixed by several U-shaped nails.

7. A composite roadbed based on rigid piles according to claim 1, characterized in that, Both the side of the general soft soil subgrade away from the waterlogged soft soil subgrade and the side of the waterlogged soft soil subgrade away from the general soft soil subgrade form a slope. The sand cushion layer extends beyond the corresponding slope and forms a sand and gravel extension. A drainage pipe and a filter layer are provided in the sand and gravel extension. The filter layer includes several gravel and a filter geotextile wrapped around the gravel. A clay seal layer is provided on the sand and gravel extension.

8. A composite roadbed based on rigid piles according to claim 7, characterized in that, The filter geotextile is a polypropylene needle-punched nonwoven geotextile with a unit area mass of 300 g / m², a thickness of not less than 2.4 mm, a width of not less than 3 m, a longitudinal and transverse tensile strength of not less than 9.5 kN / m, a longitudinal and transverse tensile elongation of not more than 50%, a vertical permeability coefficient of not less than 0.05 cm / s, a longitudinal and transverse tear strength of not less than 0.24 kN, and a CBR puncture strength of not less than 1.5 kN.

9. A composite roadbed based on rigid piles according to claim 7, characterized in that, A drainage ditch is provided on the side of the general soft soil roadbed away from the waterlogged soft soil roadbed and on the side of the waterlogged soft soil roadbed away from the general soft soil roadbed, and the drainage ditch is connected to the corresponding drainage pipe.

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