A structure for improving drainage capacity in later period of soft ground treatment by surcharge preloading

Abstract

The utility model discloses a kind of structures for improving drainage capacity in later period of soft ground treatment of heaped load precompression, including blind ditch and vertical water-collecting well, the blind ditch includes longitudinal blind ditch and transverse blind ditch, the longitudinal blind ditch is set along road trend and is located in the lowest point of heaped load precompression soft foundation center, the transverse blind ditch includes several groups arranged at intervals along road trend, and the trend of each group transverse blind ditch is perpendicular to the trend of longitudinal blind ditch Vertical intersection is provided with vertical water-collecting well, and the longitudinal blind ditch and transverse blind ditch are communicated and intersected to collect water by the vertical water-collecting well, the blind ditch is cooperatively constituted by that first geotextile is wrapped in the outer circumferential side of the pipe wall of soft permeable pipe with several broken stones along circumference, the vertical water-collecting well is cooperatively constituted by that second geotextile is wrapped in the outer circumferential side of reinforcement cage along circumference.

Description

Technical Field

[0001] This utility model relates to the field of municipal transportation technology, specifically to a structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment. Background Technology

[0002] Surcharge preloading is a common technique for treating soft soil foundations in highway, port, and airport engineering projects. Its principle is to apply a preload to accelerate the drainage of pore water from the soft soil, thereby achieving soil consolidation and settlement, and improving the bearing capacity of the foundation. In a surcharge preloading system, the horizontal drainage layer (usually a medium-coarse sand cushion) and the vertical drainage body (such as plastic drainage boards) are the key drainage channels.

[0003] However, existing surcharge preloading technology often suffers from a significant decrease in drainage capacity in the later stages. The main reasons are as follows: First, during the long-term preloading process, the pores of the horizontal sand cushion layer are easily blocked by the movement and deposition of fine-grained soil, resulting in a significant reduction in its horizontal water conductivity. Second, after the roadbed is surcharged, the roadbed cross-section will settle in a basin shape during the construction period, causing the previously set horizontal drainage system to become low in the middle and high on both sides. The larger the surcharge, the greater the settlement at the center of the embankment, which may lead to poor drainage or failure, greatly affecting the roadbed treatment effect. Utility Model Content

[0004] The purpose of this invention is to provide a structure that improves the drainage capacity in the later stages of surcharge preloading soft foundation treatment to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A structure for improving the drainage capacity of soft foundation under surcharge preloading includes blind drains and vertical collection wells. The blind drains include longitudinal and transverse blind drains. The longitudinal blind drains are arranged along the road direction and located at the lowest point of the center of the soft foundation under surcharge preloading. The transverse blind drains include several groups arranged at intervals along the road direction, and the direction of each group of transverse blind drains intersects perpendicularly with the direction of the longitudinal blind drains. A vertical collection well is set at the perpendicular intersection, and the longitudinal and transverse blind drains are connected and collected through the vertical collection well. The blind drains are formed by wrapping several crushed stones circumferentially around the outer periphery of the flexible permeable pipe with a first geotextile. The vertical collection well is formed by wrapping a second geotextile circumferentially around the outer periphery of a reinforcing cage.

[0007] Preferably, the surcharge preloading soft foundation includes a backfill soil layer, a medium-coarse sand cushion layer, and a dredged fill soil layer arranged sequentially from top to bottom.

[0008] Preferably, the blind drain is arranged horizontally along the medium-coarse sand cushion layer.

[0009] Preferably, the vertical water collection well is installed vertically through the backfill soil layer, the medium-coarse sand cushion layer and the dredged soil layer, with its top end penetrating through the top surface of the backfill soil layer and its bottom end located inside the dredged soil layer.

[0010] Preferably, the bottom perimeter of the vertical water collection well is fixed by stacking stones.

[0011] Preferably, the distance between two adjacent sets of transverse blind drains is 30 to 50 meters.

[0012] Preferably, the cross-section of the blind drain is an inverted isosceles trapezoidal structure.

[0013] Preferably, the flexible permeable pipe has a diameter of 80 mm and its wall has several permeable holes.

[0014] Preferably, the diameter of the steel cage is 1000mm, and its sidewalls are provided with several permeable grids.

[0015] By adopting the above technical solution, this utility model has the following advantages compared with the prior art:

[0016] 1. This utility model provides a structure to improve the drainage capacity in the later stage of surcharge preloading soft foundation treatment. By connecting the longitudinal blind drains, transverse blind drains and vertical collection wells at their intersections, a complete drainage network that is "crisscrossed and interconnected" is formed. This network not only greatly shortens the drainage path of pore water in the horizontal drainage layer, but also actively guides the groundwater collected by the blind drains upward through the vertical collection wells as the main channel, completely solving the problem of poor drainage in the central area of ​​large-area soft foundation, significantly improving the later drainage efficiency and accelerating the consolidation of the foundation.

[0017] 2. This utility model provides a structure to improve the drainage capacity in the later stages of surcharge preloading soft foundation treatment. The blind drain adopts a structure in which a first geotextile wraps around crushed stone and a flexible permeable pipe, while the vertical sump adopts a structure in which a second geotextile wraps around a reinforcing cage. The geotextile plays an excellent reverse filtration role, allowing water to pass freely while effectively preventing surrounding fine soil particles from intruding into the voids of the crushed stone or the interior of the reinforcing cage. This fundamentally avoids the problem of drainage channels being blocked by soil particles, ensuring that the drainage system maintains efficient and stable drainage capacity throughout the entire preloading period and even in the later stages. Attached Figure Description

[0018] Figure 1 This is a typical cross-sectional layout diagram of the present invention;

[0019] Figure 2 This is a plan view of the horizontal drainage layer of this utility model;

[0020] Figure 3 This is a cross-sectional view of the blind drain and vertical drainage well in this practical application;

[0021] Figure 4 This is the elevation view of the practical blind drain;

[0022] Figure 5 This is the elevation view of the vertical water collection well for practical use. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0024] It should be noted that in this utility model, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element of this utility model must have a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0025] Example

[0026] Please refer to Figures 1 to 5 As shown, this utility model discloses a structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment, including a blind ditch 1 and a vertical collection well 2. The blind ditch 1 includes a longitudinal blind ditch 11 and a transverse blind ditch 12. The longitudinal blind ditch 1 is set along the road direction and is located at the lowest point of the center of the surcharge preloading soft foundation 3. The transverse blind ditch 12 includes several groups arranged at intervals along the road direction, with a spacing of 30-50m between adjacent groups of transverse blind ditch 12. The direction of each group of transverse blind ditch 12 intersects perpendicularly with the direction of the longitudinal blind ditch 11. A vertical collection well 2 is set at the perpendicular intersection, and the longitudinal blind ditch 11 and the transverse blind ditch 12 are connected and collected through the vertical collection well 2. The blind ditch 1 is formed by wrapping several crushed stones 14 circumferentially around the outer periphery of the flexible permeable pipe 15 with a first geotextile 13. The vertical collection well 2 is formed by wrapping a second geotextile 21 circumferentially around the outer periphery of the reinforcing cage 22.

[0027] By connecting the longitudinal blind drain 11, the transverse blind drain 12 and the vertical water collection well 2 at their intersection, a complete drainage network that is "crisscrossed and interconnected" is formed. This not only greatly shortens the drainage path of pore water in the horizontal drainage layer, but also allows the groundwater collected by the blind drain 1 to be actively guided upward through the vertical water collection well 2 as the main channel. This completely solves the problem of poor drainage in the central area of ​​a large soft foundation, significantly improves the efficiency of subsequent drainage, and accelerates the consolidation of the foundation.

[0028] Blind drain 1 employs a structure where a first geotextile 13 wraps around crushed stone 14 and a flexible permeable pipe 15, while the vertical sump 2 employs a structure where a second geotextile 21 wraps around a reinforcing cage 22. The geotextile provides excellent filtration, allowing water to pass freely while effectively preventing fine soil particles from intruding into the voids of the crushed stone or the interior of the reinforcing cage 22. This fundamentally avoids the problem of drainage channels becoming clogged due to soil accumulation, ensuring that the drainage system maintains efficient and stable drainage capacity throughout the preloading period and even into the later stages. The geotextile, crushed stone, and reinforcing cage used are all common engineering materials, inexpensive, and readily available. The flexible permeable pipe and the reinforcing cage 22 provide reliable skeletal support, ensuring the structural stability of the drainage channels under soil pressure and preventing collapse.

[0029] The surcharge preloaded soft foundation 3 includes a backfill soil layer 31, a medium-coarse sand cushion layer 32, and a dredged fill soil layer 33 arranged sequentially from top to bottom.

[0030] Blind drain 1 is arranged horizontally on the medium-coarse sand cushion layer 32. Vertical sump 2 is installed vertically through the backfill layer 31, the medium-coarse sand cushion layer 32, and the dredged fill layer 33, with its top end penetrating the top surface of the backfill layer 31 and its bottom end located inside the dredged fill layer 33. The bottom perimeter of the vertical sump 2 is fixed by stacking stones 23.

[0031] The cross-section of blind drain 1 is an inverted isosceles trapezoid. The diameter of flexible permeable pipe 15 is 80mm, and its wall has several permeable holes. The diameter of steel cage 22 is 1000mm, and its sidewall has several permeable grids.

[0032] The implementation process of this embodiment is as follows:

[0033] Excavation of Blind Drain 1: Within the already laid medium-coarse sand cushion layer 32, blind drain 1 is excavated manually in conjunction with small machinery. First, a longitudinal blind drain 11 with a depth of 0.4 meters and a bottom width of 0.5 meters is excavated along the road centerline. Its longitudinal slope is consistent with the road design slope, but not less than 0.3%, to ensure smooth water flow. Then, along the road direction, transverse blind drain 12 is excavated perpendicular to the longitudinal blind drain 11 at intervals of 40 meters. Its depth and width are the same as those of the longitudinal blind drain 11. The cross-section of all drains is excavated into an inverted isosceles trapezoidal structure.

[0034] Laying longitudinal and transverse blind drains: In the excavated trench, first lay a layer of geotextile, so that it is tightly attached to the bottom and sidewalls of the trench.

[0035] Place a flexible permeable pipe 15 with a diameter of 80 mm at the center of the bottom of the trench. The pipe wall is densely covered with permeable holes. Fill the area around the flexible permeable pipe 15 with crushed stone 14 with a particle size of 20-40 mm until the entire trench is filled, and then lightly compact it.

[0036] Finally, the first geotextile 13 on the side of the trench is turned up to wrap the crushed stone 14, and then firmly overlapped at the top to form a complete closed filter layer. Thus, the longitudinal blind ditch 11 and the transverse blind ditch 12 are constructed and naturally connected at their intersection.

[0037] Constructing a vertical water collection well 2: At the vertical intersection of each transverse blind ditch 11 and longitudinal blind ditch 12, a drilling rig or pipe sinking method is used to construct a vertical well that penetrates the backfill soil layer 31, the medium-coarse sand cushion layer 32 and extends at least 1.0 meter into the underlying hydraulic fill layer 33.

[0038] A cylindrical steel cage 22 with a diameter of 1000mm is constructed, and its side walls are bound with wire mesh to form a permeable grid. It is then hoisted and placed into the vertical shaft. The top of the steel cage 22 should be approximately 0.5 meters above the top surface of the backfill layer 31, and the bottom should be located within the dredged fill layer 33.

[0039] Around the bottom of the steel cage 22, boulders 23 are piled up and fixed to prevent it from sinking or shifting. A second geotextile 21 is wrapped around the outer perimeter of the steel cage 22 to form a filter layer to prevent fine soil particles from entering the well.

[0040] Final construction: After the blind drain and sump are installed, continue backfilling in layers and compact the backfill soil to the design elevation before proceeding with the subsequent surcharge preloading construction.

[0041] The working principle of this embodiment is as follows: During the surcharge preloading process, pore water in the soft soil foundation first flows into the horizontal medium-coarse sand cushion layer under pressure. However, over time, the sand cushion layer may become clogged. At this point, the structure of this invention begins to play its main role: pore water seeps through the geotextile filter into the crisscrossing blind drain network and converges into the flexible permeable pipes. The water collected by the blind drain network eventually flows to the vertical collection wells at each confluence point, and then the water in the vertical collection wells is pumped out, effectively reducing the groundwater level and pore water pressure, thereby continuously improving the drainage and consolidation environment of the soft soil foundation, and maintaining excellent drainage performance even in the later stages of treatment.

[0042] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the scope of the claims.

Claims

1. A structure for improving the drainage capacity in the later stages of surcharge preloading soft foundation treatment, characterized in that: The system includes blind drains and vertical collection wells. The blind drains include longitudinal blind drains and transverse blind drains. The longitudinal blind drains are set along the road direction and located at the lowest point of the center of the surcharge preloaded soft foundation. The transverse blind drains include several groups arranged at intervals along the road direction, and the direction of each group of transverse blind drains intersects perpendicularly with the direction of the longitudinal blind drains. A vertical collection well is set at the perpendicular intersection, and the longitudinal blind drains and transverse blind drains are connected and collected through the vertical collection well. The blind drains are formed by wrapping several crushed stones around the outer periphery of the flexible permeable pipe wall with a first geotextile. The vertical collection well is formed by wrapping a second geotextile around the outer periphery of the reinforcing cage.

2. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 1, characterized in that: The surcharge preloading soft foundation includes, from top to bottom, a backfill soil layer, a medium-coarse sand cushion layer, and a dredged fill soil layer.

3. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 2, characterized in that: The blind drain is arranged horizontally along the medium-coarse sand cushion layer.

4. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 2, characterized in that: The vertical water collection well is installed vertically through the backfill soil layer, the medium-coarse sand cushion layer and the dredged soil layer, with its top end penetrating through the top surface of the backfill soil layer and its bottom end located inside the dredged soil layer.

5. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 2, characterized in that: The bottom perimeter of the vertical water collection well is secured by stacking stones.

6. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 1, characterized in that: The spacing between two adjacent sets of transverse blind drains is 30 to 50 meters.

7. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 1, characterized in that: The cross-section of the blind drain is an inverted isosceles trapezoidal structure.

8. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 1, characterized in that: The flexible permeable pipe has a diameter of 80mm and its wall has several permeable holes.

9. The structure for improving the drainage capacity in the later stage of surcharge preloading soft foundation treatment as described in claim 1, characterized in that: The diameter of the steel cage is 1000mm, and its sidewalls are provided with several permeable grids.

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