Anti-settlement construction method for backfilling of culvert back of lengthened circular pipe culvert of widened high-filled roadbed

Abstract

The invention provides an anti-sedimentation construction method for culvert back backfilling of a lengthened circular pipe culvert of a widened high-filled roadbed. The construction method comprises the steps that an existing pipe culvert is dismantled; reinforcing the foundation; reinforcing the cushion layer; arranging a transition well; pouring a pipe seat; arranging a pipe joint interface; and roadbed culvert back earthwork backfilling. According to the method, the foundation settlement amount in the foundation reinforcement range and the foundation settlement amount in the non-reinforcement range are obtained through calculation, so that the circular pipe culvert foundation reinforcement range and number are determined, settlement at the transition well is minimum, and smooth transition of foundation settlement at the transition well and the newly-built pipe culvert is achieved. The transition well structure is designed to replace a circular pipe culvert section, structure cracking caused by sedimentation can be better avoided, and the structure can be used for the splicing condition of circular pipe culverts with different diameters.

Description

Technical Field

[0001] The invention belongs to the technical field of highway reconstruction and expansion construction of widened and high-filled roadbed connected to long circular culverts, and in particular relates to a culvert backfilling and anti-settlement construction method for widened and high-filled roadbed connected to long circular culverts. Background Art

[0002] With the rapid development of China's economy, the traffic volume has increased day by day due to trade exchanges, population travel and other reasons. The designed vehicle traffic volume of some original first-class highways and expressways can no longer meet people's travel needs. The daily traffic volume of expressways is large, and the congestion is even more serious during holidays. In order to optimize the original expressway projects, the number of expressway reconstruction and expansion projects is increasing. The culvert widening project is an important part of highway reconstruction and expansion. Since the construction time of the new and old culverts is relatively long, the settlement of the old roadbed has been basically completed, while the settlement of the new culvert foundation has just begun. The settlement difference between the new and old culvert foundations can easily lead to cracking of the culvert. In order to solve the above technical problems, the present invention designs a construction method for anti-settlement of the culvert backfill by widening and high-filling roadbed and connecting the long circular culvert. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for anti-settlement construction of a widened and high-filled roadbed connected to a long circular culvert and backfilled at the back of the culvert, thereby solving the problem of culvert cracking caused by uneven settlement by innovating the foundation treatment, culvert reinforcement and culvert backfill construction technology of the widened and high-filled roadbed connected to the long circular culvert.

[0004] The present invention achieves the above technical objectives through the following technical means.

[0005] A construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling a roadbed and connecting it to a long circular culvert, characterized in that it includes the following steps:

[0006] Step 1: At the junction of the old culvert and the new culvert, remove the old opening, end wall, foundation and adjacent pipe section;

[0007] Step 2: The foundation of the transition well and the culvert at the joint is reinforced with deep mixing piles to form a composite foundation;

[0008] Step 3: Use C25 concrete to pour the foundation cushion at the bottom of the transition well at the construction joint, with a pouring thickness of 10cm, and lay a single layer of bidirectional steel bars;

[0009] Step 4: Set up a transition well at the junction of the old culvert and the new culvert;

[0010] Step 5: pouring and constructing pipe seat;

[0011] Step 6: Installation and processing of pipe joint interface;

[0012] Step 7: Backfill construction of high-fill roadbed culvert back.

[0013] Furthermore, in step 2, the composite foundation settlement is calculated using the composite compression modulus method:

[0014] The settlement S1 of the composite foundation reinforcement area is calculated using the composite compression modulus method, as follows:

[0015] E ps =δE p +(1+v)E s

[0016] Among them, E ps represents the compression modulus of the composite foundation; δ represents the area replacement rate of the composite foundation; E p Indicates the compression modulus of the pile; E s represents the soil compression modulus;

[0017] The load on the composite foundation is borne by the reinforced piles and the soil, and the load borne by the composite foundation is further obtained:

[0018] P=δP p +(1+δ)P s

[0019] Where, P represents the load borne by the composite foundation; P p Indicates the load shared by the body; P s It represents the load shared by the soil between piles; the settlement S1 of the composite foundation within the reinforcement range is:

[0020]

[0021] Where, h represents the pile length; E c represents the composite foundation modulus;

[0022] in:

[0023] E c =(1-δ)E s +δ·E p ·k·h

[0024]

[0025]

[0026] γ m =2.5h(1-u)

[0027] Among them, γ0 represents the shear modulus of pile diameter; u represents the Possion ratio of soil;

[0028] The settlement S2 of the newly built non-reinforced area is:

[0029] S2=m s Sc

[0030] Among them, m s Indicates sedimentation coefficient; S c represents the primary consolidation settlement;

[0031] Reinforcement along the extension direction of the culvert: The soil in the transition well foundation range is uniformly reinforced. In order to ensure a smooth transition between the foundation settlement within the reinforcement range and the foundation settlement of the newly built culvert, soil reinforcement is also carried out along the direction of the newly built culvert starting from the intersection of the newly built culvert and the transition well. The number of mixing piles here is compared with the number of mixing piles at the transition well. The proportion of gradually decreases, and finally a smooth transition of foundation settlement is achieved;

[0032] The reinforcement width is B+2×5tan30°, where B represents the width of the transition well, calculated from the edge of the transition well at a diffusion angle of 30°.

[0033] Furthermore, in step 4, the thickness of the transition well wall, top plate and bottom plate are all 30 cm, the concrete strength adopts C30 concrete, and a double layer of 16 mm diameter steel mesh is evenly arranged in the structure, and the vertical steel bars are arranged in a plum blossom shape with a spacing of 45 cm between the two layers of steel mesh.

[0034] Furthermore, in step 5, the concrete surface of the pipe seat is tightly fitted with the pipe body of the culvert, and the pipe seat is cast in two times. During the casting process, attention is paid to the setting of the foundation settlement joint, and at the same time, attention is paid to reserving 2 to 3 cm of pipe wall thickness and placing the pipe segment seat slurry concrete. After the pipe segment is placed, the part above the pipe bottom is cast, and the combination of new and old concrete and the combination of the pipe base and the pipe wall are ensured.

[0035] Furthermore, in step 6, when installing the spigot pipe, ensure that its interface is straight and the annular gap is uniform, and install a special rubber ring or fill it with waterproof material, and seal it with cement mortar and maintain it; when installing the flat pipe, the joint width is 10 to 20 mm, ensure that the interface surface is flat, and use elastic impermeable materials to fill it tightly. The method of increasing the joint width shall not be used to meet the culvert length requirements. Wire mesh is set at the pipe joint interface, and cement mortar is used for sealing and maintenance to ensure that the joints of the pipe joints are free of discontinuities, cracks, hollows and leaks.

[0036] Furthermore, in step 7, steps are dug at the back of the platform at a slope of 1:2, with a step width of not less than 1m. The step joint range is ≥4H+(3-5) steps dug from the center line of the culvert to both sides, where H is the height of the roadbed fill at the back of the platform. The bottom layer of the first step is paved with geocells with a laying length of ≥2H+3, and two layers of 20cm7% lime soil are laid on the top of the geocells with a compaction degree of ≥96%; the backfill material within the range of 50cm from the bottom of the culvert seat to the top of the culvert 1 is backfilled with lightweight foam concrete, and the top is backfilled to the designed elevation with materials that are similar in properties to the existing roadbed filler or more conducive to splicing, and compacted in layers. A steel-plastic grid is laid within a horizontal range of 6 meters at the top step; the fill on the top of the culvert and on both sides of the culvert body within a range of not less than twice the aperture is symmetrically compacted in layers, and the relative density reaches 96%.

[0037] The present invention has the following beneficial effects:

[0038] (1) The foundation settlement in the reinforcement range and the non-reinforcement range is calculated, so as to determine the scope and quantity of the circular culvert foundation reinforcement, minimize the settlement at the transition well, and achieve a smooth transition between the transition well and the newly built culvert.

[0039] (2) The difference in roadbed settlement at the junction of the new and old roadbeds is large, which is a weak link in the quality control of circular culvert construction. The present invention designs a transition well structure to replace the circular culvert segment. Compared with the conventional construction method of setting culvert settlement joints and planting reinforcement, the transition well structure is designed by analyzing the stress conditions at the transition well. The transition well can better avoid structural cracking caused by settlement, and the structure can be used for the splicing of circular culverts of different diameters.

[0040] (3) Special treatment was carried out on the roadbed at the junction of the new and old circular culverts, and the scope of special treatment was clearly defined to ensure uniform stress on the backfill interface.

[0041] (4) The present invention innovates the foundation treatment, culvert reinforcement, and culvert backfill construction process of the widened high-fill roadbed connected to the long circular culvert, thereby effectively solving the problem of culvert cracking caused by uneven settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the connection between the transition well and the new and old culverts;

[0043] Figure 2 for Figure 1 AA section view in;

[0044] Figure 3 This is a schematic diagram of the backfill of the circular culvert.

[0045] In the figure: 1- pipe culvert; 2- transition well; 3- cushion layer; 4- pipe seat; 5- steel-plastic grille. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0047] The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling a roadbed and connecting it to a long circular culvert according to the present invention comprises the following steps:

[0048] Step 1: dismantle the existing pipe culvert 1;

[0049] At the junction of the old culvert and the new culvert, the old opening, end wall, foundation and the adjacent pipe section are demolished.

[0050] Step 2: Foundation reinforcement;

[0051] Due to the characteristics of soft soil such as high natural water content, large porosity, high compressibility and low shear strength, deep mixing piles are used to reinforce the transition well 2 and the culvert foundation at the connection point. The reinforcement depth is not less than 5 meters. The composite compression modulus method is used to calculate the composite foundation settlement.

[0052] The settlement S1 of the composite foundation reinforcement area is calculated using the composite compression modulus method, as follows:

[0053] E ps =δE p +(1+δ)E s

[0054] Among them, E ps represents the compression modulus of the composite foundation; δ represents the area replacement rate of the composite foundation; E p Indicates the compression modulus of the pile (Mpa); E s It represents the compression modulus of soil (Mpa).

[0055] The load on the composite foundation is borne by the reinforced piles and the soil, and the load borne by the composite foundation is further obtained:

[0056] P=δP p +(1+δ)P s

[0057] Where, P represents the load borne by the composite foundation (Mpa); P p Indicates the load shared by the body (Mpa); P s Indicates the load shared by the soil between piles (Mpa).

[0058] The settlement S1 of composite foundation within the reinforcement range is:

[0059]

[0060] Where, h represents the pile length; E c represents the composite foundation modulus;

[0061] in:

[0062] E c =(1-δ)E s +δ·E p ·k·h

[0063]

[0064]

[0065] γ m =2.5h(1-u)

[0066] Among them, γ0 represents the shear modulus of pile diameter; u represents the Possion ratio of soil;

[0067] The settlement S2 of the newly built non-reinforced area is:

[0068] S2=m s S c

[0069] Among them, m s Indicates sedimentation coefficient; S c Represents the primary consolidation settlement.

[0070] Reinforcement along the extension direction of culvert 1: The soil in the transition well foundation range is evenly reinforced. To ensure a smooth transition between the foundation settlement in the reinforcement range and the foundation settlement of the newly built culvert, soil reinforcement is also carried out along the direction of the newly built culvert 1 starting from the junction of the newly built culvert 1 and the transition well 2. The number of mixing piles is compared with the number of mixing piles at the transition well. The proportion gradually decreases, and finally a smooth transition of foundation settlement is achieved.

[0071] The reinforcement width is B+2×5tan30°, where B represents the width of the transition well, calculated from the edge of the transition well at a diffusion angle of 30°.

[0072] Step 3: reinforcement of cushion layer 3;

[0073] The foundation cushion layer 3 at the bottom of the transition well 2 at the joint is made of C25 concrete, poured with a thickness of 10cm, and paved with φ12@200 single-layer bidirectional steel bars.

[0074] Step 4: Transition well 2 setting;

[0075] Reference Figure 1 , 2At the junction of the old culvert and the new culvert, the old opening and the adjacent pipe section are removed, and a joint is set at the junction to reinforce the transition well 2. The thickness of the wall, top plate and bottom plate of the transition well 2 are all 30cm. The concrete strength adopts C30 concrete. A double layer of 16mm diameter steel mesh is evenly set in the structure. Between the two layers of steel mesh, vertical steel bars are set in a plum blossom shape with a spacing of 45cm. (Stress conditions: The constant load on the transition well 2 includes the deadweight of the well body, the soil pressure on the side and top of the well body, and the live load on the well body, that is, the vehicle load, is distributed on the assumed horizontal plane of the well top through the backfill at a diffusion angle of 30°; the vertical reaction force of the base is assumed to be evenly distributed through the foundation; the lateral pressure strength of the transition well 2 is calculated according to the horizontal load caused by the soil column above the horizontal plane of the transition well). The foundation of the new and old culvert pipe seats is connected to the steel bars of the transition well 2 through embedded bars.

[0076] Step 5: pouring the pipe seat 4;

[0077] Reference Figure 1 , 2 The pipe seat 4 of the pipe culvert 1 is responsible for supporting the pipe section. If the pipe seat 4 is not well attached to the pipe section, the supporting reaction force will be concentrated, which may cause cracks in the pipe section. Therefore, no matter whether the pipe section is placed on concrete, masonry foundation or natural foundation, the concrete surface of the pipe seat 4 is required to be in close contact with the pipe body, so that the force on the pipe section can be uniform. The pipe seat 4 can be poured in two times, and attention should be paid to the setting of the foundation settlement joint. At this time, attention should also be paid to reserving the thickness of the pipe wall and placing the slurry concrete of the pipe section seat 2 to 3 cm. After the pipe section is placed, the part above the pipe bottom should be poured, and the combination of new and old concrete and the combination of the pipe base and the pipe wall should be ensured.

[0078] Step 6: Pipe joint interface;

[0079] When installing the spigot pipe, its interface should be straight, the annular gap should be uniform, and a special rubber ring should be installed or filled with waterproof materials such as asphalt and hemp, and sealed and maintained with cement mortar. When installing the flat pipe, the joint width should be 10-20mm, the interface surface should be flat, and elastic impermeable materials should be used to fill it tightly. The method of increasing the joint width should not be used to meet the culvert length requirements. Wire mesh should be installed at the pipe joint interface, and cement mortar should be used for sealing and maintenance. The joints of the pipe joints should not have discontinuities, cracks, hollows, or water leaks.

[0080] Step 7: Backfill the high-fill roadbed culvert back with earthwork;

[0081] Reference Figure 3, the steps are dug at the back of the platform according to the slope of 1:2, and the width of the steps is not less than 1m. The step joint range is ≥4H+(3~5) (H is the height of the back of the platform roadbed fill) from the center line of the culvert 1 to both sides. The geocell is laid at the bottom of the first step, and the laying length is ≥2H+3. Two layers of 20cm7% lime soil are laid on the top of the geocell, and the compaction degree is ≥96%; the backfill material from the bottom of the pipe seat 4 of the culvert 1 to the top of the culvert 1 is backfilled with lightweight foam concrete, and the top is backfilled with materials with similar properties to the existing roadbed filler or more conducive to splicing to the designed elevation, compacted in layers, and the steel-plastic grid 5 is laid within 6 meters in the horizontal direction of the top step. The fill on the top of the culvert and on both sides of the culvert body within a range of not less than twice the aperture must be compacted in layers and symmetrically, and the relative density reaches 96%. Through this treatment method, the roadbed can make the interface of the backfill of the culvert evenly stressed.

[0082] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling a roadbed and connecting it to a long circular culvert, characterized in that: The process includes the following: Step 1: At the junction of the old culvert and the new culvert, remove the old opening, end wall, foundation and adjacent pipe section; Step 2: The foundations of the transition well (2) and the culvert (1) at the connection point are reinforced with deep mixing piles to form a composite foundation; Step 3: Use C25 concrete to pour the bottom foundation cushion layer (3) of the transition well (2) at the joint, with a pouring thickness of 10 cm, and lay a single layer of bidirectional steel bars; Step 4: Setting a transition well (2) at the junction of the old culvert and the new culvert; Step 5: pouring and constructing the pipe seat (4); Step 6: Installation and processing of pipe joint interface; Step 7: Backfill construction of high-fill roadbed culvert back.

2. The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling roadbed and connecting it to a long circular culvert according to claim 1 is characterized in that: In step 2, the composite foundation settlement is calculated using the composite compression modulus method: The settlement S1 of the composite foundation reinforcement area is calculated using the composite compression modulus method, as follows: E ps =δE p +(1+δ)E s Among them, E ps represents the compression modulus of the composite foundation; δ represents the area replacement rate of the composite foundation; E p Indicates the compression modulus of the pile; E s represents the soil compression modulus; The load on the composite foundation is borne by the reinforced piles and the soil, and the load borne by the composite foundation is further obtained: P=δP p +(1+δ)P s Where P represents the load borne by the composite foundation; P p Indicates the load shared by the body; P s Indicates the load shared by the soil between piles; The settlement S1 of composite foundation within the reinforcement range is: Where, h represents the pile length; E c represents the composite foundation modulus; in: E c =(1-δ)E s +δ·E p ·k·h c m =2.5h(1-u) Among them, γ0 represents the shear modulus of pile diameter; u represents the Possion ratio of soil; The settlement S2 of the newly built non-reinforced area is: S2=m s S c Among them, m s Indicates sedimentation coefficient; S c represents the primary consolidation settlement; Reinforcement along the extension direction of the culvert (1): The soil in the foundation range of the transition well (2) is uniformly reinforced. In order to ensure a smooth transition between the foundation settlement within the reinforcement range and the foundation settlement of the newly built culvert, soil reinforcement is also carried out along the direction of the newly built culvert (1) starting from the junction of the newly built culvert (1) and the transition well (2). The number of mixing piles is compared with the number of mixing piles at the transition well. The proportion of gradually decreases, and finally a smooth transition of foundation settlement is achieved; The reinforcement width is B+2×5tan30°, where B represents the width of the transition well (2) and is calculated from the edge of the transition well (2) at a diffusion angle of 30°.

3. The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling roadbed and connecting it to a long circular culvert according to claim 1 is characterized in that: In step 4, the thickness of the wall, top plate and bottom plate of the transition well (2) is 30 cm, the concrete strength adopts C30 concrete, and a double layer of 16 mm diameter steel mesh is evenly arranged in the structure, and the vertical steel bars are arranged in a plum blossom shape with a spacing of 45 cm between the two layers of steel mesh.

4. The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling roadbed and connecting it to a long circular culvert according to claim 1 is characterized in that: In step 5, the concrete surface of the pipe seat (4) is tightly fitted with the pipe body of the culvert (1). The pipe seat (4) is poured twice. During the pouring process, attention is paid to the setting of the foundation settlement joint, and at the same time, attention is paid to reserving 2 to 3 cm of pipe wall thickness and placing the pipe joint seat slurry concrete. After the pipe joint is placed, the part above the pipe bottom is poured, and the combination of new and old concrete and the combination of the pipe base and the pipe wall is ensured.

5. The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling roadbed and connecting it to a long circular culvert according to claim 1 is characterized in that: In step 6, when installing the spigot pipe, ensure that its interface is straight and the annular gap is uniform, and install a special rubber ring or fill it with waterproof material, and seal it with cement mortar and maintain it; when installing the flat pipe, the joint width is 10 to 20 mm, ensure that the interface surface is flat, and use elastic impermeable materials to fill it tightly. The method of increasing the joint width shall not be used to meet the culvert length requirements. Wire mesh is set at the pipe joint interface, and cement mortar is used for sealing and maintenance to ensure that the joints of the pipe joints are free of discontinuity, cracks, hollows and leakage.

6. The construction method for anti-settlement by backfilling the back of a culvert by widening and high-filling roadbed and connecting it to a long circular culvert according to claim 1 is characterized in that: In the step 7, steps are dug at the back of the platform according to a slope of 1:2, and the width of the steps is not less than 1m. The step joint range is ≥4H+(3-5) steps dug from the center line of the culvert (1) to both sides, where H is the height of the roadbed fill at the back of the platform. The bottom layer of the first step is paved with geocells, with a laying length of ≥2H+3, and two layers of 20cm7% lime soil are laid on the top of the geocells, with a compaction degree of ≥96%; the backfill material within the range of 50cm from the bottom of the pipe seat (4) of the culvert (1) to the top of the culvert 1 is backfilled with lightweight foam concrete, and the top is backfilled with materials with properties similar to or more conducive to splicing as the existing roadbed filler to the designed elevation, compacted in layers, and a steel-plastic grid (5) is laid within a horizontal direction of 6 meters at the top step; the fill on the top of the culvert and on both sides of the culvert body within a range of not less than twice the aperture is symmetrically compacted in layers, and the relative density reaches 96%.

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