High filling road section light soil widening construction method

Abstract

The invention discloses a light soil widening construction method for a high-filling road section, and belongs to the technical field of highway reconstruction and extension, the widening side of an existing roadbed is excavated to form widening steps, drilling is performed to implant anti-sliding anchor rods, and reinforcing meshes are laid to form an integral anti-sliding and anti-overturning structure; the light soil is adopted for layered pouring construction, the self-leveling and self-compacting characteristics of the light soil are utilized, rolling and vibrating are not needed, and vertical widening is achieved. Construction does not need sloping, and a large amount of land acquisition and demolition cost is saved; connection and fixation between the prefabricated panel and the stand column can be rapidly achieved, the actual construction efficiency is improved, the structure adjustment is flexible, different stand column structures and installation errors of actual construction can be adapted, the connection stability between the prefabricated panel and the stand column is guaranteed, and the practicability is high. The method is suitable for rapid reconstruction and extension projects of high-fill road sections such as expressways and urban expressways.

Description

Technical Field

[0001] This invention relates to the field of road and bridge construction technology, and in particular to a method for widening lightweight soil sections in high-fill road sections. Background Technology

[0002] Early-built four-lane expressways can no longer meet the ever-increasing traffic demands, making widening and expansion on both sides or one side the most economical and effective means to improve traffic capacity. However, in high-fill sections such as mountainous areas, hilly areas, and suburban areas, the traditional widening method of "slope cutting + step excavation + layered compaction" has the following prominent problems: The project involves a large amount of land acquisition and demolition. Due to the limitations of the existing roadbed slope, a significant amount of additional land needs to be acquired for the widening side. The demolition of buildings, power and telecommunications lines, and agricultural and forestry crops has led to soaring project costs and uncontrollable construction periods. Quality control during filling is difficult. In high-fill sections, the thickness of conventional fine-grained soil layers during compaction is typically ≤30cm, requiring repeated watering, drying, and compaction testing. Construction during the rainy season is prone to "springy soil" and localized under-compaction, resulting in significant differences in post-construction settlement and causing road surface cracking, bridge approach slab settlement, and other defects. Stability risks are prominent, as the modulus of the new and old roadbed fill materials differs greatly, and the splicing interface is merely a "step + geogrid". The simple combination of "fences" and "grids" is insufficient in terms of resistance to slippage, overturning, and bending tension. During the operation period, under the coupled effects of traffic loads and rainwater infiltration, longitudinal cracks or even overall slippage are easily generated along the interface, requiring long-term grouting maintenance and resulting in high life-cycle costs. Traditional slope protection schemes cause significant disturbance to the original topography, with high excavation and high filling damaging vegetation and occupying scarce arable land resources. Construction efficiency is low, and the compaction process relies on heavy equipment, making equipment relocation difficult when the work surface is narrow. At the same time, it is greatly affected by the weather, with work basically stopping at night and during the rainy season, making it difficult to meet the rapid reconstruction and expansion needs of highways that require "construction while traffic is open".

[0003] To overcome the aforementioned shortcomings, the industry has successively tried lightweight fillers such as fly ash, EPS blocks, and foamed lightweight soil. Among them, foamed lightweight soil has been applied in scenarios such as bridge abutment backfilling and soft soil foundation load reduction due to its advantages such as adjustable wet density, self-leveling, self-compacting, no need for compaction, and fast construction speed. However, in the specific case of widening and resurfacing high-fill sections, the existing technology still has significant shortcomings: the interface treatment is simple, the shear strength is low, and it is difficult to resist the lateral earth pressure of the high fill and the additional stress caused by traffic loads; the construction operation is complex and inefficient, making it difficult to meet the current demand for short-term and efficient construction operations in highway reconstruction and expansion. Therefore, the existing construction technology for widening high-fill sections using lightweight soil needs further improvement and optimization. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for widening elevated embankment sections using lightweight soil, comprising the following steps: S101. Excavate the existing roadbed widening side according to the design alignment to form widening steps, and install protective netting on the side of the roadbed of the widening steps; S201. A baffle foundation is set on the outer side of the step surface of the widened steps, and a crushed stone cushion layer is laid. S301. Several transverse anchors are installed on the side of the roadbed of the widened step, and several vertical anchors are installed on the step surface of the widened step; S401. Lay a steel mesh on the crushed stone cushion layer, and connect and fix the steel mesh to the horizontal anchor and the vertical anchor; S501. Laying precast panels and detachable steel formwork; S601. The selected proportion of lightweight soil is used to pour the lightweight soil pouring layer. After the lightweight soil has initially set, the steel formwork is removed, and an impermeable geotextile is laid on top of the lightweight soil pouring layer. Then, conventional roadbed filler is backfilled to form a widened roadbed structure. S701. After the widening is completed, the pavement structure layer is constructed on the lightweight soil pouring layer to complete the lightweight soil widening construction of the high fill section.

[0005] As a further explanation of the present invention, when pouring lightweight soil in step S601, a layered pouring method is adopted for the pouring construction.

[0006] Furthermore, during the pouring of the lightweight soil, the steel mesh is provided between the lightweight soil layers.

[0007] Furthermore, during the pouring of the lightweight soil, several vertical anchor rods are pre-embedded, and the steel mesh is connected and fixed to the horizontal anchor rods and the vertical anchor rods.

[0008] Furthermore, the steel mesh is composed of several unit grids, each unit grid having several connecting parts, and the connecting parts between adjacent unit grids are staggered and then fixed by fasteners.

[0009] Furthermore, several columns are fixedly installed on the base of the baffle, and the precast panel is built on the base of the baffle. The columns and the precast panel are connected by a tie rod mechanism.

[0010] Furthermore, the pull rod mechanism includes a first pull rod and a second pull rod; one end of the first pull rod is a hook end and the other end is a threaded end, the threaded end being provided with threads and a fastening nut; one end of the second pull rod is a hook end and the other end is a through end, the threaded end being provided with an elongated hole through which the first pull rod can pass.

[0011] Furthermore, the tie rod mechanism includes a support base and a sliding base; one end of the support base is an abutment part, and the other end is a screw part; the sliding base is disposed on the screw part and locked by adjusting the nut, and the two sides of the sliding base are provided with tie arms for connecting the prefabricated panel.

[0012] Furthermore, the pull arm is hinged to the sliding seat.

[0013] The beneficial effects of this invention are: The advantages of this construction method are as follows: By vertically cutting a stepped interface into the widening side of the existing roadbed, drilling holes to insert anti-slip anchors, and laying steel mesh, an overall anti-slip and anti-overturning structure is formed; lightweight soil is used for layered pouring construction, utilizing the self-leveling and self-compacting properties of lightweight soil, eliminating the need for compaction and vibration, thus achieving vertical widening. Construction does not require slope protection, saving significant land acquisition and demolition costs, and reducing the land area per lane by 6-10m; it enables rapid connection and fixation between precast panels and columns, improving actual construction efficiency; and the structure is flexible, adapting to different column structures and actual installation errors, ensuring the stability of the connection between precast panels and columns. It is suitable for rapid reconstruction and expansion projects of high-fill sections such as highways and urban expressways. Attached Figure Description

[0014] Figure 1 This is a flowchart of the construction method for widening lightweight soil sections in high-fill road sections according to the present invention; Figure 2 This is a schematic diagram of the construction elevation of the lightweight soil widening project in a high-fill section according to an embodiment of the present invention; Figure 3 This is a schematic diagram of an embodiment of the tie rod mechanism of the present invention; Figure 4 This is a schematic diagram of another embodiment of the tie rod mechanism of the present invention; Figure 5 This is a schematic diagram of the steel mesh arrangement in an embodiment of the present invention; Figure 6 This is a diagram illustrating the steel mesh structure according to an embodiment of the present invention.

[0015] Attached reference numerals: 1. Roadbed; 2. Protective net; 3. Baffle foundation; 4. Crushed stone cushion layer; 5. Horizontal anchor bolt; 6. Vertical anchor bolt; 7. Steel mesh; 8. Precast panel; 9. Road structure layer; 10. Lightweight soil pouring layer; 11. Connecting part; 12. First tie rod; 13. Second tie rod; 14. Fastening nut; 15. Connecting rod; 16. Column; 17. Support seat; 18. Sliding seat; 19. Adjusting nut; 20. Tie arm; 21. U-shaped clip. Detailed Implementation

[0016] Example:

[0017] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] This embodiment of the invention addresses the above-mentioned problems by providing a method for widening lightweight soil sections in high-fill roadways, comprising the following steps: S101. Excavate the existing roadbed 1 widening side according to the design alignment to form a widening step, and install a protective net 2 on the side of the roadbed 1 widening step; S201. A baffle foundation 3 is set on the outer side of the step surface of the widened step, and a crushed stone cushion layer 4 is laid. S301. Several transverse anchors 5 are installed on the side of the roadbed 1 of the widened step, and several vertical anchors 6 are installed on the step surface of the widened step; S401. Lay a steel mesh 7 on the crushed stone cushion layer 4, and connect and fix the steel mesh 7 to the horizontal anchor 5 and the vertical anchor 6; S501. Lay precast panels 8 and detachable steel formwork; S601. The selected proportion of lightweight soil is used to pour lightweight soil layer 10. After the lightweight soil has initially set, the steel formwork is removed, and impermeable geotextile is laid on top of lightweight soil layer 10. Then, conventional roadbed filler is backfilled to form a widened roadbed structure. S701. After the widening is completed, the pavement structure layer 9 is constructed on the lightweight soil pouring layer 10 to complete the lightweight soil widening construction of the high fill section.

[0020] The construction method of widening high-fill sections using lightweight soil, as described in this invention, minimizes land occupation. Vertical filling on the widening side eliminates the need for slope protection, saving 6-10m of land per side and largely avoiding land acquisition and demolition, thus protecting farmland and buildings. Construction is rapid; the lightweight soil is self-leveling and self-compacting, requiring no rolling or vibration, and a single layer can be completed in 1 hour, shortening the construction period by more than 40% compared to traditional layered rolling. Traffic remains open during the widening process. Anti-slip anchors and steel mesh increase the interface shear strength by 3 times, resulting in post-construction differential settlement of <5mm and no longitudinal cracks. Foamed lightweight soil can be used, with the foaming agent fully foamed through a mechanical foaming system, uniformly mixed with cement slurry, and then poured in place, reducing additional foundation stress by 30% and minimizing soft soil treatment. This method saves on land acquisition costs, earthwork transportation costs, and post-construction maintenance costs, making it suitable for rapid reconstruction and expansion projects of high-fill sections such as highways and urban expressways.

[0021] Specifically, in this embodiment, when pouring lightweight soil in step S601, a layered pouring method is adopted. Specifically, the thickness of each layer of lightweight soil is controlled within a reasonable range according to the lightweight soil pouring construction process and specifications to ensure the uniform compaction and structural stability of the lightweight soil. Before layered pouring, the surface of the next layer of poured lightweight soil needs to be treated, including removing surface laitance, loose particles, and debris, to enhance the bonding force between the new and old lightweight soil. Simultaneously, the formwork needs to be inspected to ensure its accurate positioning and firm support, and a release agent is applied to the inside of the formwork to prevent the lightweight soil from sticking to the formwork. After each layer is poured, timely curing is carried out. Curing methods include covering with a moisturizing film or spraying a curing agent to keep the surface of the lightweight soil moist, ensuring the normal development of the lightweight soil's strength. In addition, during the layered pouring process, mix proportion tests of lightweight soil are conducted. For example, pouring tests of lightweight soil with various different mix proportions are carried out, and core sampling is performed to check the performance of lightweight soil with different strengths. The optimal mix proportion is selected according to the actual situation for pouring construction. The next layer can only be poured when the strength of the previous layer of lightweight soil reaches more than 70% of the design strength, so as to ensure that a good overall structure is formed between each layer of lightweight soil.

[0022] Specifically, in this embodiment, during the pouring of the lightweight soil, the reinforcing mesh 7 is provided between the lightweight soil layers 10. (See attached image.) Figure 1 As shown, after the crushed stone cushion layer 4 is leveled, several horizontal anchor bolts 5 and vertical anchor bolts 6 are driven in. The horizontal anchor bolts 5 and vertical anchor bolts 6 are made of threaded steel and are pre-embedded in the roadbed 1. After laying the steel mesh 7, it is anchored and fixed using the corresponding horizontal anchor bolts 5 and vertical anchor bolts 6. By setting the steel mesh 7 between the lightweight soil pouring layers 10, the overall strength and crack resistance of the lightweight soil structure can be effectively improved, resisting stress concentration caused by the shrinkage of the lightweight soil itself or external loads, thereby ensuring the stability and durability of the lightweight soil structure.

[0023] For details, please see the appendix. Figure 6 As shown, in this embodiment, the reinforcing mesh 7 is composed of several unit meshes and is made of galvanized steel sheets. The galvanized steel sheets are cut at intervals and bent into a wavy shape to serve as connecting parts 11. The wavy connecting parts 11 allow the connecting parts 11 between adjacent unit meshes to be staggered and connected. U-shaped clips 21 are inserted at the connection points for secure connection. This process is repeated to connect and expand the unit meshes, forming the reinforcing mesh 7.

[0024] Specifically, in this embodiment, a plurality of columns 16 are fixedly installed on the baffle foundation 3, and the precast panel 8 is installed on the baffle foundation 3. The columns 16 and the precast panel 8 are connected by a tie rod mechanism. (See attached diagram) Figure 3In one embodiment shown, the pull rod mechanism includes a first pull rod 12 and a second pull rod 13. One end of the first pull rod 12 is a hook end, and the other end is a threaded end. The threaded end has an external thread and a matching fastening nut 14. The fastening nut 14 is a hexagonal nut, and its inner diameter matches the external thread of the first pull rod 12. It is used to lock the relative position between the first pull rod 12 and the second pull rod 13 to prevent loosening during use. One end of the second pull rod 13 is a hook end, and the other end is a through-hole end. The through-hole end has an elongated hole through which the first pull rod 12 can pass. Connecting rings are pre-embedded on the prefabricated panel 8, and the connecting rings are connected to each other by connecting rods 15 to form an integral panel. In practical applications, the hook ends of the first pull rod 12 and the second pull rod 13 hook onto the connecting rod 15, and the threaded end of the first pull rod 12 passes through the elongated hole of the second pull rod 13. After adjusting the relative position of the two with the column 16, they are tightened to improve the structural stability.

[0025] As attached Figure 4 In another embodiment shown, the tie rod mechanism includes a support base 17 and a sliding base 18. One end of the support base 17 is an abutment portion, and the other end is a screw portion. The sliding base 18 is disposed on the screw portion and locked by an adjusting nut 19. Tie arms 20 for connecting the precast panel 8 are provided on both sides of the sliding base 18. In practical applications, the connecting rod 15 is hooked by the hook portion at the front end of the tie arm 20. Rotating the adjusting nut 19 causes the sliding base 18 to slide relative to the tie arm 20, thereby tightening the connecting rod 15 and achieving a quick connection and fastening effect. In a preferred embodiment, the tie arm 20 is hinged to the sliding base 18. During the tightening operation of the tie rod mechanism, the slight rotation of the tie arm 20 can eliminate the influence of actual construction errors, ensuring an effective connection between the precast panel 8 and the column 16, and avoiding situations where incomplete connections affect construction quality. Based on the tie rod mechanism structure of the present invention, the connection and fixation between the prefabricated panel 8 and the column 16 can be quickly realized, improving the actual construction efficiency. Moreover, the structure is flexible and can adapt to different column 16 structures and actual construction installation errors, ensuring the stability of the connection between the prefabricated panel 8 and the column 16.

[0026] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. In short, all variations made within the scope of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A high fill section light soil widening construction method, characterized in that, The method comprises the following steps: S101. Excavating the existing roadbed to form a widening step according to the design line, and setting a protective net on the side of the roadbed of the widening step; S201. Setting a baffle foundation outside the step face of the widening step, and laying a gravel cushion; S301. Setting a plurality of horizontal anchor rods on the side of the roadbed of the widening step, and setting a plurality of vertical anchor rods on the step face of the widening step; S401. Laying a steel mesh on the gravel cushion, and connecting and fixing the steel mesh with the horizontal anchor rods and the vertical anchor rods; S501. Laying a prefabricated panel and a detachable steel formwork; S601. Pouring a lightweight soil pouring layer by pouring lightweight soil with a selected ratio, removing the steel formwork after the lightweight soil is initially cured, laying a permeation-resistant geotextile on the top of the lightweight soil pouring layer, and backfilling a conventional roadbed filler to form a widened roadbed structure; S701. After the widening is completed, laying a pavement structure layer on the lightweight soil pouring layer to complete the lightweight soil widening construction of the high-fill section.

2. The construction method of claim 1, wherein: In the step S601, the lightweight soil is poured by layering.

3. The construction method of claim 2, wherein the method further comprises: The steel mesh is arranged between the lightweight soil pouring layers.

4. The construction method of claim 3, wherein the method further comprises: A plurality of vertical anchor rods are embedded during the pouring of the lightweight soil, and the steel mesh is connected and fixed with the horizontal anchor rods and the vertical anchor rods.

5. The construction method of the high-filled section light soil widening according to claim 1, characterized in that: The steel mesh is composed of a plurality of unit meshes, each unit mesh has a plurality of connecting parts, the connecting parts between adjacent unit meshes are connected in an interlaced manner and are fixed by a clamping nail.

6. The construction method of the high-fill section light soil widening according to claim 1, characterized in that: A plurality of vertical anchor rods are embedded during the pouring of the lightweight soil, and the steel mesh is connected and fixed with the horizontal anchor rods and the vertical anchor rods.

7. The construction method of claim 6, wherein the method further comprises: The steel mesh is composed of a plurality of unit meshes, each unit mesh has a plurality of connecting parts, the connecting parts between adjacent unit meshes are connected in an interlaced manner and are fixed by a clamping nail.

8. The construction method of claim 6, wherein the method further comprises: A plurality of vertical anchor rods are embedded during the pouring of the lightweight soil, and the steel mesh is connected and fixed with the horizontal anchor rods and the vertical anchor rods.

9. The construction method of claim 8, wherein the method further comprises: The steel mesh is composed of a plurality of unit meshes, each unit mesh has a plurality of connecting parts, the connecting parts between adjacent unit meshes are connected in an interlaced manner and are fixed by a clamping nail. A plurality of vertical anchor rods are embedded during the pouring of the lightweight soil, and the steel mesh is connected and fixed with the horizontal anchor rods and the vertical anchor rods. The steel mesh is composed of a plurality of unit meshes, each unit mesh has a plurality of connecting parts, the connecting parts between adjacent unit meshes are connected in an interlaced manner and are fixed by a clamping nail. The baffle foundation is fixed with a plurality of vertical anchor rods, the prefabricated panel is laid on the baffle foundation, and the vertical anchor rods are connected with the prefabricated panel through a pull rod mechanism. The pull rod mechanism comprises a first pull rod and a second pull rod; one end of the first pull rod is a hook end, the other end is a threaded end, a thread and a locking nut are arranged on the threaded end; one end of the second pull rod is a hook end, the other end is a perforated end, and an elongated hole is formed in the threaded end for the first pull rod to pass through. The pull rod mechanism comprises a support seat and a sliding seat; one end of the support seat is an abutting part, and the other end is a screw part; the sliding seat is arranged on the screw part and is locked by an adjusting nut; the two sides of the sliding seat are provided with pull arms for connecting the prefabricated panel. The pull arm is hingedly connected with the sliding seat.

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