Culvert is a common drainage structure in road engineering. The culvert structure is complex and changeable, so it is puzzling to read the engineering drawings, and the wrong size judgment often leads to the rework of the project. The following small series will take you in-depth understanding of various culverts, teach you how to understand culvert engineering drawings, and calculate engineering quantities with 3D model drawings.
On the left of the picture below is a slab culvert under construction in a certain section, and on the right is a stone arch culvert.
Culvert classification
(1) Culverts are classified into reinforced concrete culverts, concrete culverts, brick culverts, stone culverts, wooden culverts and metal culverts according to building materials.
(2) Culverts are classified into circular tube culvert, arch culvert, box culvert and slab culvert according to structural form. This classification method is often used in engineering.
(3) Culverts are classified according to the number of holes, including single hole, double hole and multi-hole.
(4) Culverts are divided into open culverts and concealed culverts according to whether there is covering soil at the top of the cave (the filling soil at the top of the cave is more than 50cm).
Culvert composition
Culvert is a drainage structure consisting of three parts: hole, hole body and foundation. The following figure is a three-dimensional exploded view of reinforced concrete circular pipe culvert, from which we can know the names, positions and structures of various parts of the culvert.
Culvert engineering drawing
Culverts pass through the road from below the pavement and are buried in the subgrade soil. Although there are many types of culverts, the graphic methods are basically the same.
Culvert engineering drawings are mainly composed of elevation (longitudinal section), plan, side view, necessary structural details (such as culvert body section, member reinforcement structure, wing wall section), bill of quantities, notes, etc. Various figures show the structural shape and size of the culvert, and the bill of quantities gives the materials and quantities of various components of the culvert, with notes explaining some contents that cannot be expressed in the drawings, such as size units, construction methods and matters needing attention.
Engineering drawing characteristics
(1) In the illustration, the culvert engineering drawing takes the water flow direction as the longitudinal direction (that is, it is arranged perpendicular to the route direction), and the vertical view is replaced by the vertical view, and the section plane passes through the culvert axis.
(2) The scheme generally does not consider the covering soil above the culvert, or assumes that the soil layer is transparent. Sometimes the projection of tunnel foundation is not drawn on the plan, but expressed by elevation and section.
(3) In the side projection, the front layout of the hole is taken as the side view. When the shapes of the inlet hole and the outlet hole are different, the layout of the inlet hole and the outlet hole should be drawn separately.
(4) The profile of the tunnel body, the arrangement of steel bars and the profile of the wing wall can also be shown in another drawing.
Drawing reading method
Summarize the understanding first, and then read it carefully;
First the whole, then the parts, and then combine them to imagine the whole.
(1) Understand the name, size unit, location (mileage pile number) and related requirements of the culvert from the title bar, corner mark and notes on the drawings.
(2) Understand what basic expressions are used for culverts, what special expressions are used, the cutting position and projection direction of each section, and the main functions of each projection.
According to the structural characteristics of each component of culvert, it can be divided into several sections along the length direction or along the width direction. Then analyze each part.
On the basis of analysis, compare the projection, profile, section and local enlargement of culvert, make clear the relationship between each component, consider the characteristics of culvert map and imagine the whole. In the process of reading the drawings, read them carefully in combination with the bill of materials and notes.
The engineering drawing of reinforced concrete slab culvert mainly includes the summary composition of slab culvert, the summary composition of components and the structural drawing of component reinforcement. It is represented by elevation view (longitudinal section view), plan view, side view (elevation view before the cave), wing wall details, I-I section view, etc.
Read the structural drawing of reinforced concrete double-hole circular pipe culvert
The engineering drawing of reinforced concrete circular pipe culvert is mainly composed of the summary composition of circular pipe culvert, the structural drawing of pipe joint reinforcement, pipe joint and settlement joint.
Read the structural diagram of stone arch culvert The following picture shows the general structural diagram of stone arch culvert, which is represented by semi-longitudinal section, semi-plane and side view. The semi-longitudinal section mainly expresses the internal structure of the culvert, but the structure and form of the entrance and exit are the same, and the whole culvert is symmetrical, so the semi-longitudinal section is used instead of the elevation.
Read the structural drawing of reinforced concrete box culvert
The following figure shows the three-dimensional schematic diagram and general layout of reinforced concrete box culvert. This drawing is expressed by elevation (longitudinal section), plan, side view (elevation before entrance) and culvert section.
Quantitative calculation
How to calculate the culvert quantity? This is actually not complicated, so let's talk about it in detail today. How to calculate the quantity of slab culvert? In fact, the calculation of slab culvert project is very simple, the concrete quantity can be calculated by slab, and the steel bar can be input in a single component.
Slab culvert means that the tunnel body is composed of cover plate, abutment cap, culvert abutment, foundation and expansion joint. The filling height is 1 ~ 8m, even reaching 12m. When the aperture is large and the embankment is high, the cost of the slab culvert is higher than that of the arch culvert, but the construction technology is simple and the flood discharge capacity is large, so the slab can be made centrally.
I. Construction Process of Slab Culvert
Pay-off → Excavation of foundation pit → Compaction of basement → Construction of foundation and cushion → Installation of foundation reinforcement → Installation of foundation formwork → Concrete pouring of foundation → Installation of culvert formwork → Concrete pouring of culvert → Precast and hoisting of cover plate (cast-in-place cover plate) → Construction of ancillary works.
1. Depart:
Positioning and setting out the foundation according to the drawings, and determining the center line, sideline and elevation.
2. Foundation pit excavation:
Firstly, according to the safety technical disclosure, the pipe trench shall be excavated manually, and the excavator shall be used for excavation only after it is confirmed that there is no pipeline. In the process of construction, it is necessary to prevent over-excavation and keep the slope gradient correct. The foundation pit of cover box culvert with a depth of more than 4m is protected by plastic film. Mechanical excavation is carried out until it is close to the designed pit bottom elevation or slope boundary, and 300 mm thick soil layer is reserved for manual excavation. Around the foundation pit, 200mm high woven bags are piled up to fill sand, and the earthwork excavated during foundation pit construction is piled up 2m away from the foundation pit, and the height is not more than1.5 m. During construction, the inspection and control of slope and support should be strengthened, and vehicles should leave the pit. After foundation pit excavation, the bottom of the pit should be leveled and trimmed. Water supply anchor rod and drainage trough: The water supply anchor rod system and drainage trough of the station, due to the small excavation depth and width, small flexible tire excavator should be selected for foundation pit excavation. The excavated earthwork shall be stacked 500mm away from the foundation pit for backfilling.
Second, the engineering quantity calculation
In the calculation of engineering quantity, the bottom plate, wall and cover plate of culvert should be calculated separately, all in cubic meters.
Calculation method and formula of culvert engineering quantity;
C20 concrete: (5.85-0.6) ×1.2× 29× 2 = 365.4m3.
C30 concrete cap: [(1.2-0.25) × 0.35 (0.6-0.35) ×1.2 ]× 29× 2 = 36.685m3.
Cover plate: 0.35× 40.25× 2× 29 = 45.675m3.
C30 cement concrete pavement: 3× 0.18× 29 =15.66m3.
Cement stabilized macadam base: 3× 0.15× 29 =13.05m3.
Gravel cushion: 3× 0.67× 29 = 58.29m3
Gravel replacement: 8.64×1.5× 29 = 375.84m3.
C25 concrete:/kloc-0 /× (8.64-0.87× 2 )× 29 = 200.1m3.
Chinese character wall: v =1/2× 0.58× (5.852-0.62 )× 0.580.58/0.6× 3.75× (5.853-0.63) =10.85m3/kloc-0.
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