1. General provisions
1.0.1 The Guidelines is formulated with a view to meet the highway construction requirement, to regulate and guide the reconnaissance design of highway culverts on the basis of relevant provisions of "Technical Standard of Highway Engineering" (JTG B01-2003) and "General Code for Design of Highway Bridges and Culverts" (JTG D60).
1.0.2 The Guidelines are applicable to reconnaissance design for all class of newly-built and reconstructed highway culverts.
1.0.3 The culvert layout not only must meet the requirements of drainage and sand-transportation, but shall also be cooperated with highway drainage system, water planning or agricultural irrigation and drainage.
1.0.4 The design for the highway culverts shall meet the requirements of safety, application, economy, esthetic appearance and environmental protection advantage, so as to make treatment in accordance with local conditions and get raw materials from local resources, so that to facilitate the construction and curing.
1.0.5 The reconnaissance design for highway culverts not only shall meet the requirements of the Guidelines, but also shall comply with provisions of current relevant standards and codes of the nation.
2. Terminologies and symbols
2.1 Terminologies
2.1.1 Culvert
Small-scale structures set to ensure the surface flow crossing the highway, it is consisted of foundation, culvert body and culvert portal.
2.1.2 Pipe culvert
The culvert with culvert body be pipe shape
2.1.3 Arch culvert
The culvert with section top of the culvert body be arcing
2.1.4 Box culvert
The culvert with culvert body be reinforced concrete box section
2.1.5 Slab culvert
Culvert with culvert body covering by reinforced concrete slab or stone slab
2.1.6 Outlet submerged culvert
The culvert with culvert portal access being submerged by stream, gross section within the culvert length coverage of the culvert body passing through water, and top being pressed by water head
2.1.7 Inlet submerged culvert
The culvert inlet is submerged by stream, only parts of culvert body is pressed by water head
2.1.8 Inlet unsubmerged culvert
The culvert with full culvert body length waterflow remain in non-pressure flow state
2.1.9 Inverted siphon
The culvert with stream on both sides of the subgrade being higher than the culvert water access and with water passing by flow pressure, this kind of culvert similar in shape with the inverted siphon
2.1.10 Catchment area
The plain area enclosed in the basin divide and culvert cross section
2.1.11 Runoff
Stream with precipitation on land confluence in rivers, lakes, marshes, ocean, water-bearing layer desert
2.1.12 Back water
The upstream water line is rising resulted from the compressing, jacking of tidal level or trunk stream water level
2.1.13 Critical velocity
The mean velocity in section causing critical depth in the open-channel flow
2.1.14 The permit velocity for no scour
It is the flow velocity adopted to ensure no scour appears when calculating the culvert and drainage
2.1.15 Wetted cross-section
Cross section that could drain stream in the river, channel or pipeline
2.1.16 Wetted perimeter
Length of the moistening boundary in part contacting with the wetted cross-sectional stream and riverbed (pipeline)
2.1.17 Hydraulic radius
Wetted cross-sectional area to wetted perimeter ratio
2.1.18 Sediment
A kind of phenomenon that sediments carried by the stream are depositing due to the slow down of the flow velocity
2.1.19 Coefficient of roughness
The coefficient integrally reflects the friction resistance impact of riverbed roughness on the stream
2.1.20 Characteristic value of material strength
It is the basic representative value of adopted material strength when designing the structure or elements. This value may be determined according to the 5th percentile of the strength probability distribution of the qualified standard materials.
2.1.21 Design value of material strength
The value that characteristic value of material strength is divided by partial coefficient of the material strength
2.1.22 Actions
The single force or distributed force applied on the structure, such as deadweight and earth pressure of automobile and structure, this kind of force is called direct action, or load; the reasons for structure additional deformation or binding deformation, such as earthquake, foundational differential settlement and temperature variation, is called indirect action. Both of them are go by the general name of actions.
2.1.23 Characteristic value of an action
Main representative value of an action; the value may be determined according to some percentile in maximum probability distribution within the design base period.
2.1.24 Design value of an action
The value after characteristic value of an action multiplied by partial coefficient
2.1.25 Effects of an action
Reflection of structure on the bear action, such as axial force, bending moment, shearing force, stress, crack and deformation of structure or elements generated by actions.
2.1.26 Combination for action effects
Random effects superposition of actions on the structure
2.1.27 Safety class
The design safety class divided according to the sequential severity caused by the structural damage
2.1.28 Coefficient for importance of a structure
The coefficient added to action effect to provide specified reliability for the structures with different safety classes
