A bridge drainage structure using permeable concrete and a calculation method for the permeability of permeable concrete

Abstract

The present invention relates to a bridge drainage structure using permeable concrete and a method for calculating the water permeability of permeable concrete, comprising: a bridge structure, a waterproof layer is applied on the top plate of the bridge structure, and on the waterproof layer, from the center line of the bridge to the outside, it includes: a carriageway asphalt concrete bridge deck pavement layer; a water collection tank, the water collection tank is arranged at the edge of the carriageway asphalt concrete bridge deck pavement layer; a permeable concrete foundation, the permeable concrete foundation is arranged adjacent to the water collection tank, and an anti-collision guardrail is arranged on the permeable concrete foundation; a sidewalk asphalt concrete bridge deck pavement layer, the sidewalk asphalt concrete bridge deck pavement layer is arranged at the edge of the permeable concrete foundation; a drainage pipeline, including a drainage pipe and a water collection pipe. The drainage structure of the present application neither affects the longitudinal prestressed pipeline layout in the bridge structure, nor is it easy for local water accumulation to occur at the transverse drainage pipe.

Description

Technical Field

[0001] The invention belongs to the field of bridge drainage, and in particular relates to a bridge drainage structure using permeable concrete and a method for calculating the water permeability of the permeable concrete. Background Art

[0002] According to the requirements of the "Design Specifications for Traffic Safety Facilities", for roads with a design speed of 60 km / h or more, a crash barrier should be installed between the sidewalk and the lane. In this case, there are three commonly used bridge deck drainage methods, depending on the installation location and direction of the drainage pipe:

[0003] (1) Separate drainage for carriageway and sidewalk

[0004] Drain holes are set at the edges of the carriageway and sidewalk to drain water downwards. Figure 1 .

[0005] (2) Centralized drainage of sidewalks

[0006] Set up horizontal drainage holes on the dividing guardrail to allow rainwater from the roadway to flow onto the sidewalk, and then set up drainage pipes on the sidewalk to drain water downwards. Figure 2 .

[0007] (3) Raised sidewalks for centralized drainage

[0008] The sidewalk is raised by setting supporting curbs, and the sidewalk slab is set on it. Horizontal drainage pipes are set on the guardrails and curbs, and then drainage pipes are set under the sidewalk slab, see Figure 3 .

[0009] Although these three drainage methods can solve the problem of bridge deck drainage, they also have certain disadvantages:

[0010] (1) Separate drainage for carriageway and sidewalk

[0011] For large box girders, the cantilever width is generally between 2.0m and 3.5m, while the sidewalk width is generally between 2 and 4m. A carriageway drainage solution is adopted, and the drain pipe is arranged near the root of the flange plate, which affects the layout of the longitudinal prestressed pipe. For some wider sidewalks, the drain pipe needs to be laid inside the box. Water leakage from the drain holes will cause corrosion of the steel bars and prestressed steel, and have an adverse effect on the durability of the main beam. When centralized drainage is performed, the water collecting pipe under the drain hole is complicated to set up, and construction and maintenance are inconvenient.

[0012] (2) Centralized drainage of sidewalks

[0013] The sidewalks are centrally drained, and when it rains, it is easy for local water accumulation to occur in the horizontal drainage pipes, affecting the passage of pedestrians and vehicles, and posing a safety hazard.

[0014] (3) Raised sidewalks for centralized drainage

[0015] The sidewalk needs to be raised and additional sidewalk slabs need to be installed, which has a complex structure and high cost. The size of the drainage holes is limited by the height of the curb. The drainage holes are small and easily blocked by garbage and sediment on the bridge surface. The drainage holes are located under the sidewalk slabs, which are difficult to inspect and maintain. Summary of the invention

[0016] The present application aims to provide a new type of bridge drainage structure which does not affect the longitudinal prestressed pipe layout in the bridge structure and is not prone to local water accumulation in the transverse drainage pipe. The present application provides a bridge drainage structure using permeable concrete, including:

[0017] Bridge structure: A waterproof layer is applied to the top plate of the bridge structure. On the waterproof layer, from the center line of the bridge outward, the following are included in order:

[0018] The asphalt concrete bridge deck pavement layer of the carriageway has a slope of 2% inclining away from the center line of the bridge;

[0019] The water collection tank is arranged at the edge of the asphalt concrete bridge deck pavement layer of the carriageway, and the water collection tank is obtained by shaping the material for paving the asphalt concrete bridge deck pavement layer of the carriageway;

[0020] Permeable concrete foundation, the permeable concrete foundation is set close to the water collection tank, and the anti-collision guardrail is set on the permeable concrete foundation;

[0021] The asphalt concrete bridge deck pavement of the pedestrian walkway is arranged at the edge of the permeable concrete foundation and has a slope of 2% inclining away from the center line of the bridge;

[0022] The drainage pipeline includes a drain pipe and a collecting pipe, wherein the drain pipe is arranged at the far end of the asphalt concrete bridge deck pavement of the sidewalk, and the drain pipe runs through the cantilever of the bridge structure; the collecting pipe is connected to the drain pipe, and is used to collect rainwater discharged from the drain pipe, and collect the rainwater and discharge it to a designated location.

[0023] Furthermore, the cross-section of the permeable concrete foundation is rectangular.

[0024] Furthermore, during construction, epoxy coated steel bars are first embedded at appropriate locations during the construction of the main beam of the bridge structure, and then a permeable concrete foundation is cast using permeable concrete.

[0025] Furthermore, after the construction of the permeable concrete foundation is completed, the anti-collision guardrail steel bars are tied, and ordinary concrete is used to cast the anti-collision guardrail on the permeable concrete foundation. In order to ensure the durability of the structure and avoid steel bar corrosion, the anti-collision guardrail steel bars are epoxy-coated steel bars coated with epoxy resin coating.

[0026] Furthermore, the bridge structure is a prestressed concrete box girder.

[0027] On the other hand, the present application also provides a method for calculating the water permeability of the permeable concrete of the above-mentioned bridge drainage structure using permeable concrete, comprising the following steps:

[0028] 1) Calculate Q p,t ,in

[0029] Q p,t =C p C t q n,t

[0030] Among them, Q p,t is the design flow rate with a design return period of P years and a design rainfall duration of t minutes;

[0031] C p is the return period conversion coefficient, which is a constant and can be found in Table 9.1.7-1 of the Highway Drainage Design Code;

[0032] C t is the precipitation duration conversion coefficient, which is a constant and can be found in Table 9.1.7-2 of the Highway Drainage Design Code;

[0033] q n,t is the t-minute rainfall intensity that occurs once in n years, which can be found according to Figure 9.1.7-1 of the Highway Drainage Design Code;

[0034] 2) Calculate the water discharge per linear meter, Q, where

[0035] Q=Q p,t M

[0036] in,

[0037] Q is the amount of water discharged per linear meter;

[0038] M is the catchment area per linear meter, which can be calculated using the road width;

[0039] 3) Select an appropriate safety factor and calculate the water permeability q of concrete

[0040] q=γQ / L

[0041] Where q is the water permeability of concrete;

[0042] γ is the safety factor;

[0043] L is the effective drainage height calculated based on the thickness of the permeable concrete foundation after deducting the sidewalk paving.

[0044] Furthermore, according to the water permeability q of the concrete obtained in step 3), appropriate permeable concrete is selected to cast the permeable concrete foundation.

[0045] Furthermore, the permeable concrete foundation uses 16 cm thick C30 permeable concrete.

[0046] The beneficial effects of this application are:

[0047] 1. It solves the problem of local water accumulation at the drain outlet of the guardrail, which is beneficial to pedestrian safety.

[0048] 2. The drainage pipe is placed at the edge of the sidewalk, which does not affect the prestressing arrangement of the main beam;

[0049] 3. No need to set up sidewalk slabs, convenient construction and low cost;

[0050] 4. During operation, you only need to clean up the garbage on the bridge surface, which makes maintenance easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 This is a schematic diagram of the structure of the existing technology of separate drainage for the carriageway and the sidewalk;

[0053] Figure 2 It is a schematic diagram of the structure of the centralized drainage of sidewalks in the prior art;

[0054] Figure 3 A schematic diagram of a prior art structure for elevated centralized drainage of sidewalks;

[0055] Figure 4 A schematic structural diagram of a bridge drainage structure using permeable concrete provided in an embodiment of the present invention;

[0056] Figure 5 A schematic cross-sectional view of a bridge drainage structure using permeable concrete provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] like Figure 4-5 As shown, a specific scheme of a bridge drainage structure using permeable concrete in an embodiment of the present application includes:

[0059] A bridge structure 1, such as a prestressed concrete box girder, has a waterproof layer 2 applied to the top plate of the bridge structure. The waterproof layer includes, from the center line of the bridge outward, the following:

[0060] The asphalt concrete bridge deck pavement layer 3 of the carriageway is preferably 10 cm thick and is arranged on the waterproof layer 2 of the top plate of the bridge structure 1 with a slope of 2% (inclined in a direction away from the center line of the bridge);

[0061] The water collecting tank 4 is arranged at the edge of the asphalt concrete bridge deck pavement layer of the carriageway, and the water collecting tank is obtained by shaping the material for paving the asphalt concrete bridge deck pavement layer of the carriageway;

[0062] Permeable concrete foundation 5, the permeable concrete foundation 5 is set close to the water collection tank, preferably with a thickness of 16cm, and the anti-collision guardrail is set on the permeable concrete foundation; during construction, first pre-embed the epoxy coated steel bars 6 during the construction of the main beam of the bridge structure 1, and then pour the permeable concrete foundation. After the foundation construction is completed, the anti-collision guardrail steel bars 10 are tied, and ordinary concrete is used to cast the anti-collision guardrail on the permeable concrete. In order to ensure the durability of the structure and avoid steel corrosion, the anti-collision guardrail steel bars 10 are epoxy coated steel bars coated with epoxy resin coating;

[0063] The sidewalk asphalt concrete bridge deck pavement layer 7 is preferably 4 cm thick and is arranged at the edge of the permeable concrete foundation with a slope of 2% (inclined away from the center line of the bridge);

[0064] The drainage pipeline includes a drain pipe 8 and a collecting pipe 9, wherein the drain pipe is arranged at the far end of the asphalt concrete bridge deck pavement of the sidewalk (the end away from the center line of the bridge), and the drain pipe runs through the cantilever of the bridge structure; the collecting pipe is connected to the drain pipe, which is used to collect rainwater discharged from the drain pipe and collect the rainwater and discharge it to a designated location.

[0065] The method for calculating the water permeability of the permeable concrete of the bridge drainage structure using permeable concrete in the present application comprises the following steps:

[0066] 1) Calculate Q p,t ,in

[0067] Q p,t =C p C t q n,t

[0068] Among them, Q p,t is the design flow rate (m 3 / s);

[0069] C p is the return period conversion coefficient, which is a constant and can be found in Table 9.1.7-1 of the Highway Drainage Design Code (JTG / TD33);

[0070] C t is the precipitation duration conversion coefficient, which is a constant and can be found in Table 9.1.7-2 of the Highway Drainage Design Code (JTG / TD33);

[0071] q n,t is the t-minute rainfall intensity once in n years, which can be found according to Figure 9.1.7-1 of the Highway Drainage Design Code (JTG / TD33);

[0072] 2) Calculate the water discharge per linear meter, Q, where

[0073] Q=Q p，t M

[0074] in,

[0075] Q is the amount of water discharged per linear meter;

[0076] M is the catchment area per linear meter, which can be calculated using the road width;

[0077] 3) Select an appropriate safety factor and calculate the water permeability q of concrete

[0078] q=γQ / L

[0079] Where q is the water permeability of concrete;

[0080] γ is the safety factor;

[0081] L is the effective drainage height calculated by the thickness of the permeable concrete foundation after deducting the sidewalk pavement;

[0082] 4) Select appropriate permeable concrete according to the concrete's permeability q.

[0083] In a specific embodiment of the present application, a bridge in a certain city is designed to meet the design standard of a secondary highway. If the carriageway and sidewalk are drained separately, the cross-section of the flange root will inevitably be weakened to a certain extent, and the layout of the longitudinal prestressed steel strands will be affected. Therefore, the present application adopts a permeable concrete guardrail design for the bridge. Specifically, the bridge is a prestressed concrete box girder with a full width of 12m, a sidewalk width of 1.5m, and a flange plate cantilever width of 2.75m. A waterproof layer is completely applied on the top plate of the box girder. On the waterproof layer, from the center line of the bridge to the outside, a 400cm wide and 10cm thick asphalt concrete is laid as the bridge deck. The asphalt concrete has a slope of 2%. A sump is set at the edge of the asphalt concrete. The permeable concrete foundation is set adjacent to the sump. The permeable concrete foundation adopts 16cm thick C30 permeable concrete. The crash barrier is set on the permeable concrete foundation. The longitudinal reinforcement in the permeable concrete and the crash barrier is coated with epoxy resin coating; a sidewalk asphalt concrete bridge deck pavement layer is set on the other side of the permeable concrete foundation, which is 4cm thick and has a slope of 2%; a drain pipe and a collector pipe are set at the cantilever end of the flange plate, wherein the drain pipe runs through the cantilever of the bridge structure; the collector pipe is connected to the drain pipe to collect rainwater discharged from the drain pipe and collect and discharge the rainwater to a designated location.

[0084] When it rains, the rainwater falling on the bridge deck will flow into the ditch along the cross slope of the bridge deck made of asphalt concrete. The ditch is close to the permeable concrete foundation. The rainwater in the ditch can pass through the guardrail and directly flow into the sidewalk, and then flow along the slope of the asphalt concrete bridge deck pavement layer of the sidewalk to the drain pipe, and then flow into the water collection pipe, thus solving the problem of local water accumulation at the guardrail drainage outlet, which is beneficial to pedestrian safety.

[0085] The calculation method of water permeability of permeable concrete in the embodiment of the present application is as follows:

[0086] According to the Highway Drainage Design Code, the 10-minute rainfall intensity q 5，10 2.0mm / min. This project is a secondary highway, and the design rainfall recurrence period of drainage is 3 years. According to Table 9.1.7-1, the recurrence conversion coefficient C in Hubei region is p Take 0.86. This project has two lanes and the precipitation duration is 5 minutes. According to Table 9.1.7-2, the precipitation duration conversion coefficient is C t Take 1.25, so

[0087] Q p，t =C p C t q 5，10 =2.15mm / min

[0088] This project is a two-lane bridge with a one-way drainage width of 4m. Therefore, the discharge volume per linear meter is Q

[0089] Q=Q p，t M = 8.6 × 10 6 mm 3 / min

[0090] According to the drainage design of this project, the effective drainage height is 10cm, which is the thickness of the permeable concrete foundation after deducting the sidewalk paving. At the same time, the design discharge volume takes into account a safety factor of 2. Therefore, the design discharge volume per linear meter is Q 设

[0091] Q 设 =0.1q≥2Q

[0092] The water permeability of concrete is q

[0093] q≥2.87mm / s

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bridge drainage structure using permeable concrete, characterized in that: include: A bridge structure (1), wherein the bridge structure (1) is a prestressed concrete box girder, a waterproof layer (2) is applied on the top plate of the bridge structure (1), and the waterproof layer, from the center line of the bridge outward, comprises: A carriageway asphalt concrete bridge deck pavement layer (3), wherein the carriageway asphalt concrete bridge deck pavement layer (3) has a slope of 2% inclining in a direction away from the center line of the bridge; A water collecting trough (4), the water collecting trough (4) is arranged at the edge of the asphalt concrete bridge deck pavement layer of the carriageway, and the water collecting trough is obtained by shaping the material for paving the asphalt concrete bridge deck pavement layer (3) of the carriageway; A permeable concrete foundation (5), wherein the permeable concrete foundation (5) is made of 16 cm thick C30 permeable concrete. The permeable concrete foundation (5) is arranged adjacent to the water collection tank (4), and the anti-collision guardrail is arranged on the permeable concrete foundation. During construction, epoxy coated steel bars (6) are pre-embedded at appropriate positions during the construction of the main beam of the bridge structure (1), and then the permeable concrete foundation (5) is cast using permeable concrete. After the construction of the permeable concrete foundation (5) is completed, the anti-collision guardrail steel bars (10) are tied, and ordinary concrete is used to cast the anti-collision guardrail on the permeable concrete foundation (5). To ensure the durability of the structure and avoid steel corrosion, the anti-collision guardrail steel bars (10) are epoxy coated steel bars coated with epoxy resin coating. A sidewalk asphalt concrete bridge deck pavement layer (7), wherein the sidewalk asphalt concrete bridge deck pavement layer is arranged at the edge of the permeable concrete foundation and has a slope of 2% inclining away from the center line of the bridge. The drainage pipeline comprises a drainage pipe (8) and a water collecting pipe (9), wherein the drainage pipe (8) is arranged at the far end of the sidewalk asphalt concrete bridge deck pavement layer (7), and the drainage pipe (8) runs through the cantilever of the bridge structure (1); the water collecting pipe (9) is connected to the drainage pipe (8) and is used to collect rainwater discharged from the drainage pipe (8), and collect the rainwater and discharge it to a designated location.

2. The structure according to claim 1, characterized in that: The cross section of the permeable concrete foundation (5) is rectangular.

3. The method for calculating the water permeability of the permeable concrete of the bridge drainage structure using permeable concrete according to claim 1 or 2, characterized in that: The following steps are involved: 1) Calculation ,in in, is the design flow rate with a design return period of P years and a design rainfall duration of t minutes (m³ / s); is the return period conversion coefficient, which is a constant and can be found in Table 9.1.7-1 of the Highway Drainage Design Code (JTG / TD33); is the precipitation duration conversion coefficient, which is a constant and can be found in Table 9.1.7-2 of the Highway Drainage Design Code (JTG / TD33); is the t-minute rainfall intensity once in n years, which can be found according to Figure 9.1.7-1 of the Highway Drainage Design Code (JTG / TD33); 2) Calculate the water discharge per linear meter, Q, where in, Q is the amount of water discharged per linear meter; M is the catchment area per linear meter, which can be calculated using the road width; 3) Select an appropriate safety factor and calculate the water permeability q of concrete Where q is the water permeability of concrete; is the safety factor; L is the effective drainage height calculated based on the thickness of the permeable concrete foundation after deducting the sidewalk paving.

4. The method according to claim 3, characterized in that According to the water permeability q of the concrete obtained in step 3), appropriate permeable concrete is selected to cast the permeable concrete foundation (5).

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