A method for splicing construction of a U-shaped abutment of an old road in reconstruction and expansion

Abstract

The present application relates to the technical field of civil engineering, and particularly relates to a construction method for splicing of a U-shaped abutment of an old road in reconstruction and extension, comprising the following steps: according to the width of the old road in reconstruction and extension, a widened abutment is constructed on both sides of the old U-shaped abutment, a cantilever reinforced concrete vertical wall is arranged at the rear of the widened abutment to replace the original side wall of the old U-shaped abutment, the reinforced concrete vertical wall extends to the original road direction, and the rear of the widened abutment is filled with foamed lightweight soil; the present application cancels the widened side wall of the U-shaped abutment, reduces the influence of foundation excavation on the roadbed slope, adopts a counter-pulling anchor rod type lightweight soil backfill abutment, has high structural strength and high stability, is light and has fast strength increase of the lightweight soil, has high construction efficiency, and avoids the adverse effects of insufficient compaction strength and slow efficiency of the backfill of the widened narrow abutment.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads. Background Technology

[0002] With the increase in reconstruction and expansion projects, especially in mountainous areas, most of the existing road bridge abutments have a high U-shaped shape. When widening old roads to build new U-shaped abutments, the foundation is generally expanded, resulting in a large foundation excavation surface. Excavating the foundation of the new U-shaped abutment can easily expose the foundation of the old bridge abutment. Furthermore, excavating the cone slope of the old road will make the exposed surface steep. Without timely temporary support, it is very easy to cause landslides and endanger the safety of the lower construction, posing safety hazards to the old road bridge abutments, cone slopes, and side slopes.

[0003] In the existing technology, the old bridge is a U-shaped abutment. After the side wall construction of the newly widened U-shaped abutment is completed, if the width of the widened section is narrow, the working surface for backfilling between the old and new U-shaped abutment side walls is narrow, making it impossible for large compaction machinery to operate. Only small machinery can be used for manual compaction, resulting in poor compaction effect of the backfill soil behind the abutment and difficulty in ensuring construction quality. However, the compaction degree requirement for this newly spliced ​​part is relatively high, which is also a high-incidence area for subsequent bridge abutment and roadbed pavement defects. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for splicing U-shaped bridge abutments during the reconstruction and expansion of old roads, thereby solving the problems existing in the prior art. To achieve the above objective, this invention provides the following technical solution:

[0005] This invention provides a construction method for splicing U-shaped bridge abutments during the reconstruction and expansion of old roads, comprising the following steps:

[0006] Based on the width of the old road, the bridge abutment width will be widened on both sides of the old road U-shaped bridge abutment. A cantilevered reinforced concrete wall will be set behind the widened bridge abutment to replace the original side wall of the old road U-shaped bridge abutment. The reinforced concrete wall will extend in the direction of the original road. Foamed lightweight soil will be used to fill the area behind the widened bridge abutment.

[0007] As a further technical solution, the reinforcing bars connecting the reinforced concrete wall and the foamed lightweight soil are connected to the reinforced concrete wall using a rebar anchoring method.

[0008] As a further technical solution, the side walls of the old road U-shaped bridge abutment are roughened before filling with foamed lightweight soil.

[0009] As a further technical solution, tie rods are installed between the old roadbed and the foamed lightweight soil to strengthen the connection between the old roadbed and the foamed lightweight soil.

[0010] As a further technical solution, the longitudinal step excavation of the old road slope excavation and step excavation route is carried out according to a slope ratio of 1:2, and the original cone slope fill within the widening range is removed.

[0011] As a further technical solution, a gravel drainage layer is installed on the top surface of the reinforced concrete vertical wall foundation near the old road slope.

[0012] As a further technical solution, the location of the reinforced concrete wall on the slope is adjusted according to the width of the widened roadbed.

[0013] As a further technical solution, before filling with foamed lightweight soil, it is necessary to ensure that the foundation pit is flat and free of water accumulation, and compaction should be carried out before filling to ensure the bearing capacity of the foundation.

[0014] As a further technical solution, two layers of steel-plastic geogrid are laid on the top surface of the foamed lightweight soil, and a composite geomembrane waterproof layer is laid on the top surface of the steel-plastic geogrid.

[0015] As a further technical solution, the outer side of the reinforced concrete wall foundation is sealed with concrete.

[0016] The beneficial effects of the present invention are as follows:

[0017] (1) The newly widened U-shaped bridge abutment of the reconstruction and expansion project needs to be connected to the old road U-shaped bridge abutment and foundation. This invention eliminates the side wall and foundation of the newly widened U-shaped bridge abutment, thereby avoiding the excavation of the side wall foundation, reducing the impact of foundation excavation on the roadbed slope, reducing construction risks, improving the safety of roadbed construction, and saving the corresponding construction measures costs.

[0018] (2) The present invention adopts a tie-anchor type foam lightweight soil backfill abutment, which has high structural strength, strong stability, and light weight. Moreover, the strength of the soil rises quickly, resulting in high construction efficiency. It avoids the adverse effects of insufficient compaction strength and slow effect of backfilling in narrow abutments. At the same time, the abutment uses lightweight materials, which reduces the uneven settlement of the widened roadbed and effectively reduces the phenomenon of bridge approach slab settlement.

[0019] (3) The construction method of the present invention can ensure that the widening of the U-shaped abutment of the old bridge of the highway is stable, safe and easy to construct, and can extend the service life of the highway and reduce the cost of later maintenance. Attached Figure Description

[0020] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute a limitation thereof. It should also be understood that these drawings are for simplicity and clarity and are not necessarily drawn to scale. The invention will now be described and explained with additional features and details using the drawings, wherein:

[0021] Figure 1 This invention illustrates the plan layout of the old road U-shaped bridgehead splicing structure in an embodiment of the invention.

[0022] Figure 2 It shows Figure 1 A schematic diagram of the spliced ​​section of the longitudinal section II;

[0023] Figure 3 It shows Figure 1 , Figure 2 Schematic diagram of the splicing section of the transverse section II-II;

[0024] Figure 4 It shows Figure 1 , Figure 2 Schematic diagram of the spliced ​​cross section of the transverse section III-III.

[0025] In the diagram: 1. Reinforced concrete vertical wall; 2. Foamed lightweight soil; 3. Widened bridge abutment; 4. U-shaped bridge abutment of the old road; 5. Concrete enclosure; 6. Slope toe line; 7. Side wall; 8. Roughened surface; 9. Old roadbed; 10. Composite geomembrane; 11. Bridge approach slab; 12. Steel-plastic geogrid; 13. Subbase; 14. Base course; 15. Surface course; 16. Concrete guardrail; 17. Excavation line of the old road slope; 18. Ground line; 19. Excavation and backfilling of bridge abutment foundation; 20. Tie anchor bars; 21. Crushed stone drainage layer; 22. C15 concrete sealing; 23. Ф10cm PVC drainage pipe; 24. Slope backfill; 25. Road design centerline. Detailed Implementation

[0026] The technical solutions in typical embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0027] like Figures 1-4 As shown in the figure, this embodiment provides a construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads, including the following steps:

[0028] Based on the width of the existing road, the width of the bridge abutment 4 will be widened on both sides of the existing U-shaped bridge abutment. After widening the bridge abutment by 3 units, a cantilevered reinforced concrete wall 1 will be installed to replace the original sidewall 7 of the existing U-shaped bridge abutment 4. The reinforced concrete wall 1 will extend towards the original road. After widening the bridge abutment by 3 units, foamed lightweight soil 2 will be used for backfilling. The location of the reinforced concrete wall 1 on the slope will be adjusted according to the width of the widened roadbed.

[0029] The newly widened U-shaped bridge abutment in the reconstruction and expansion project needs to be connected to the old road U-shaped bridge abutment and foundation. In this embodiment, the side walls and foundations of the newly widened U-shaped bridge abutment are eliminated, thereby avoiding the excavation of the side wall foundation, reducing the impact of foundation excavation on the roadbed slope, reducing construction risks, improving the safety of roadbed construction, and saving the corresponding construction measures costs.

[0030] The reinforced concrete wall 1 uses C30 concrete. The reinforced concrete wall 1 and its foundation are constructed in 10m sections. Every 10m, a 2cm through-joint is installed in the reinforced concrete wall 1, penetrating the panel and foundation, and the joint is filled with foam plastic board. Before foundation construction, the base must be leveled and compacted. Foamed lightweight soil 2 can only be poured after the foundation and panel have reached 80% strength. During the construction of foamed lightweight soil 2, temporary protective measures should be taken for the reinforced concrete wall 1 to prevent tilting and displacement.

[0031] like Figure 4 As shown, the reinforcing bars connecting the reinforced concrete wall 1 and the foamed lightweight soil 2 are connected to the concrete retaining wall using a rebar anchoring method, penetrating at least 20cm into the panel. The rebars are Ф25mm diameter tie rods (20mm), and Class A rebar anchoring adhesive is used. During construction, it must be ensured that the rebars are embedded within the foamed lightweight soil 2. The topmost rebar should be more than 40cm from the top surface of the foamed lightweight soil.

[0032] like Figure 1 As shown, before filling with foamed lightweight soil 2, the sidewalls of the old road U-shaped bridge abutment 4 are roughened to form a roughened surface 8, which can enhance the adhesion between the foamed lightweight soil 2 and the sidewalls of the old road U-shaped bridge abutment 7. At the same time, in order to strengthen the connection between the old roadbed 9 and the foamed lightweight soil 2, one φ25mm tie rod is installed every 0.5m along the direction of the road in the old road foundation pit, extending at least 2m into the old roadbed 9. This also serves as a temporary slope reinforcement measure. The tie rods should be driven in promptly after the foundation pit is excavated.

[0033] Concrete enclosure 5 is a cast-in-place concrete base, used for slope reinforcement and slope shrinkage.

[0034] Before constructing foamed lightweight soil 2, the foundation pit must be flat and free of water. Compaction should be carried out before filling to ensure the foundation bearing capacity is ≥100KPa. Foamed lightweight soil 2 should be poured in sections and layers. Before filling, the top elevation of the foamed lightweight soil should be calculated based on the site construction zoning and the longitudinal and transverse design of the route.

[0035] The bridge abutment near the old road was widened according to the expansion and reconstruction project. The transition section length was treated by backfilling the back of the abutment in accordance with the specifications. The foundation was excavated to the top surface of the widened abutment foundation. After excavation, stepped foamed lightweight soil was backfilled. Then, reinforced concrete panels were erected on the steps, and foamed lightweight soil was poured in layers.

[0036] like Figure 2 As shown, two layers of steel-plastic geogrid 12 are laid on the top surface of the foamed lightweight soil 2. The steel-plastic geogrid 12 adopts the GSGS60-60 specification. A composite geomembrane 10 is laid on the top surface as a waterproof layer. The composite geomembrane 10 adopts the OM0.3 (TCC6-M0.3) / (PET-PE) model, with one layer of geotextile and one layer of geomembrane, weighing 300g / m. 2The membrane thickness is 0.3 mm. The construction of geosynthetics should meet the requirements of JTG / T D32-2012 "Technical Specification for Application of Geosynthetics in Highways". For example... Figure 2 The diagram shows the subbase 13, base course 14, surface course 15, and concrete guardrail 16. After the foamed lightweight soil 2 is constructed and reaches its design strength, the construction of each structural layer of the road surface begins: cement-stabilized crushed stone subbase 13, cement-stabilized crushed stone base course 14, asphalt surface course 15, followed by the construction of concrete guardrail 16.

[0037] The approach slab 11 is made of C40 concrete and is cast in place. This is mainly to prevent bridge approach slabs from slabing and to serve as a smooth transition between the roadbed section and the bridge section.

[0038] The use of tie-anchor type foam lightweight soil 2 backfill abutment has high structural strength and stability. The lightweight soil has a fast strength increase and high construction efficiency, avoiding the adverse effects of insufficient compaction strength and slow effect of backfill in narrow abutment widening. At the same time, the use of lightweight materials for the abutment reduces uneven settlement of the widened roadbed and effectively reduces the phenomenon of bridge approach slab settlement.

[0039] like Figure 2 and Figure 3 As shown, the longitudinal step excavation of the old roadside slope excavation line 17 and the step excavation route shall be carried out according to a slope ratio of 1:2, with h = 1.0m. The original cone slope fill within the widening range needs to be excavated, and appropriate support measures shall be taken during construction to ensure safety. Figure 2 The ground line 18 represents the original ground position, marked with a diagonal line.

[0040] like Figure 2 As shown, the earthwork adjacent to the bridge abutment foundation was excavated and backfilled 19, and compacted with small machinery to ensure the compaction quality of the backfill soil on the top surface of the new bridge abutment foundation.

[0041] like Figure 3 and Figure 4 As shown, a gravel drainage layer 21 is installed on the top surface of the reinforced concrete wall 1 foundation near the old road slope to remove water seeping from the roadbed slope and wall gaps. A Ф10cm PVC drainage pipe 23 is used for drainage, and the bottom of the Ф10cm PVC drainage pipe 23 is backfilled with slope 24.

[0042] To prevent water flow from eroding the slope on the road surface and the outside of the reinforced concrete wall 1, the outside of the foundation of the reinforced concrete wall 1 is sealed with C15 concrete 22.

[0043] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A construction method for splicing U-shaped bridge abutments during the reconstruction and expansion of old roads, characterized in that, Includes the following steps: Based on the width of the old road, the bridge abutment width will be widened on both sides of the old road U-shaped bridge abutment. A cantilevered reinforced concrete wall will be set behind the widened bridge abutment, and the side walls and foundation of the widened bridge abutment will be eliminated. The reinforced concrete wall will extend in the direction of the original road, and foamed lightweight soil will be used to fill the area behind the widened bridge abutment. The steel bars connecting the reinforced concrete vertical wall and the foamed lightweight soil are connected to the reinforced concrete vertical wall by anchoring. Tie anchor bars are installed between the old roadbed and the foamed lightweight soil to strengthen the connection between the old roadbed and the foamed lightweight soil; Multiple layers of tie rods are buried along the depth of the foamed lightweight soil.

2. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, Before filling with foamed lightweight soil, the side walls of the old road U-shaped bridge abutment were roughened.

3. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, The longitudinal step excavation of the old road slope excavation and step excavation route shall be carried out according to a slope ratio of 1:2, and the original cone slope fill within the widening range shall be removed.

4. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, A gravel drainage layer is installed on the top surface of the reinforced concrete vertical wall foundation near the old road slope.

5. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, Adjust the location of the reinforced concrete vertical wall on the slope according to the width of the widened roadbed.

6. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, Before filling with foamed lightweight soil, the foundation pit must be flat and free of water accumulation. Compaction should be carried out before filling to ensure the bearing capacity of the foundation.

7. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, Two layers of steel-plastic geogrid are laid on the top surface of the foamed lightweight soil, and a composite geomembrane waterproof layer is laid on the top surface of the steel-plastic geogrid.

8. The construction method for splicing U-shaped bridge abutments in the reconstruction and expansion of old roads as described in claim 1, characterized in that, The outer side of the reinforced concrete wall foundation is sealed with concrete.

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