Tiêu chuẩn quốc tế

• Số hiệu / Standard Number: AASHTO HDG CHAPTER 6:2007
• Năm ban hành / Publication date: 2007
• Tình trạng / Status: A - Còn hiệu lực
• Tên tiếng Anh / Title in English: HYDRAULIC ANALYSIS AND DESIGN OF OPEN CHANNELS
• Thay thế cho / Replace: AASHTO HDG VOL VI:1999
• Số trang / Page: 80

Phạm vi áp dụng / Scope of standard

INTRODUCTION: An open channel is a conveyance in which water
flows with a free surface and may be natural or constructed.
Natural streams usually consist of a normal or low-flow channel and
adjacent floodplains. For purposes of this chapter, the term "open
channel" will include the total conveyance facility, floodplain,
and stream channel.

Open channel hydraulics is of particular importance to highway
design because of the interrelationship of channels to all highway
hydraulic structures. In the hydraulic analysis and design of
bridges and culverts, open-channel hydraulic principles are
utilized to evaluate the effects of proposed structures on water
surface profiles, flow, and velocity distributions, lateral and
vertical stability of the channel, stream regime, flood risk, and
the potential reaction of the stream to changes in variables (e.g.,
structure type, shape, location, scour control measures).

The hydraulic design process for open channels consists of
establishing criteria, developing and evaluating alternatives, and
selecting the alternative that best satisfies the established
criteria. Capital investment and probable future costs, including
maintenance and flood damages to properties, traffic service
requirements, and the stream and floodplain environment must be
considered in the design process. The detail in which risks are
considered should be commensurate with the flood hazard at the
site, economics, and current engineering practices.

Highway encroachments on streams and floodplains should be
avoided where practicable; however, encroachments are necessary in
some locations. The short- and long-term effects of changes to
natural streams should be evaluated during both the planning and
design phase of project development. Highway-related channel work
is generally local in nature and should not be associated with
extensive modifications generally referred to as channelization
projects.

In this chapter, the hydraulic engineering aspects of open
channels are discussed, proceeding from hydraulic considerations in
planning and location through studies necessary for design and
construction to hydraulic considerations as related to maintenance.
Channels along, across, approaching, and leaving the highway are
included.

The chapter is not all inclusive, but salient considerations are
discussed, suggested procedures are presented and references to
sources of more detailed information are cited.