Purpose-To provice flexible, inexpe

Purpose
-To provice flexible, inexpensive bank protection in situations where vegetation alone is inadequate to prevent erosion
Conditions where applicable
-Where erosion is caused by surface runoff or subsurface seepage
-On stream banks and stream bends with erodible soils
-In areas where submergence lasts continuously for more than a few days (e.g., situations where vegetation alone provides inadequate control)
Note: Work along the banks of a watercourse may require a permit, so consult the Nova Scotia Department of the Environment for advice.
ADVANTAGES
-Tolerates some lateral seepage if a filter fabric is used underneath
-Provides a flexible lining
-Provides a rough surface that dissipates stream’s force, therefore mini-mizing the erosion problem
-Provides immediate protection
-May be co-established with vegetation for a more natural appearance
-Adjusts to minor shifts and movement of a stream bank
-Easy to apply
-Can be placed during winter months on streambanks because trucks are able to be driven on frozen ground to the erosion site
DISADVANTAGEs
-If not properly feathered in, will cause a shift in the erosion problem up or downstream (in streambank applications)
-High initial cost if stone must be hauled any distance
-Should be placed on a well-graded slope no steeper than 2:1
-Very expensive for a large-scale application
DESIGN CONSIDETARIONS
The ability of riprap to resist erosive forces depends on water velocity and the interrelation of the size, shape, weight, and gradation of the stone, the side slopes, roughness, shape, and alignment of the channel, and the thickness of the riprap layer.
The type of stone applied depends on what is most available (quarried stone, field stone, rubble).
The stone should be of a blocky, angular shape, rather than elongated, and should be sized of a mixed gradation so that smaller stones fill the voids between the larger ones. A layer of filter stone may be required soil and the size of protective riprap above.
DESIGN STEPS
1.Select a stable slope for the soil.
2.Determine if a seepage drain is required.
3.Select the stone size.
- Use stream flow velocity ( assuming a graded channel Manning’s roughness of 0.030) to determine suitable stone size.
Stream Flw Velocity Mean Stone Diameter
m/sec.(ft./sec.) less than 2.0 (6.6)
2.0 - 2.5 (6.6 - 8.2)
2.5 - 3.0 (8.2 - 9.8)
3.0 - 3.5 (9.8 - 11.5) mm (in.)
80 -110 (3 - 4)
110 - 180 (4 -7)
180 - 220 (7 - 8.5)
220 - 330 (8.5 - 13)


Velocities greater than 3.5 m (11.5 ft.) /sec. Require a more extensive design for steambank protection and should not be attempted without the aid of a soils engineer or other person experienced in the design and installtion of erosion and sediment cotrol measures.
-Riprap should be applied at a thickness of at least 1.5 times the maximum stone size and not less than 300 mm (1 ft.) thick.
4. Select the filter material, either a geotextile or layer of filter stone, from manufacturer’s liteature or technical references.
5. Locate the riprap on the channel bank.
- Riprap design on steam channel bends or meanders should not be attempted without the aid of a soils engineer or other person experienced in the design and installation of erosion and sediment control measures.
- On sraight channel sections the riprap should protect the bank toe beneath the channel bottom and extend to the top of the bank or at least 600 mm (2 ft.) above the channel design flow water level.
- The riprap should not be placed in a manner that would constrict the channel width.
IMPLEMENTATION STEPS
1.Prepare the site ( after consultation with the Nova Scotia Department of the Environment).
- Clear the area of debris.
- Grade the banks to the recommendes slope.
- Dig out the toe trench.
- Install any seepage drains required.
2.Place the riprap.
- Lay out the filter fabric, if it is being used, or the layer of filter stone.
- Riprap can be placed by hand or by machine (backoe, etc.). (Be sure that the stone is not dropped from such a height that it will damage the filter fabric.)
-Riprap should be placed tp its full thickness in one operation.
- Blend or “ feather” the ends of the riprap section into the upstream and downstream banks so the ends do not protrude into the stream and cause eddying and further bank erosion.
-If installed under winter conditions, the riprap should be carefully placed and/ or contained to prevent it from spilling over the ice.
3. Complete the installation.
- A vegetative lining should be used on any areas that were graded but not riprapped.
MAINTENANCE
Once in place, riprap lining requires little upkeep. However, any displacement of stone should be repaired immediately.
CROSS REFERENCES
-Factsheet 1.3 Geotextile Fiter Fabric
-Factsheet 1.5 Vegetative Linings & Buffer Strips
-Factsheet 2.6 Seepage Drains

Kết quả (Việt) 1:

Mục đích-Để bảo vệ Huế ngân hàng linh hoạt, rẻ tiền trong các tình huống nơi thảm thực vật một mình là không đủ để chống xói mònTiết khi áp dụng-Xói mòn gây ra bởi dòng chảy bề mặt hoặc dưới bề mặt thấm-Trên dòng ngân hàng và dòng uốn cong với đất erodible-Trong khu vực nơi submergence kéo dài liên tục trong nhiều hơn một vài ngày (ví dụ như, tình huống nơi thảm thực vật một mình cung cấp không đầy đủ điều khiển)Lưu ý: các hoạt động dọc theo bờ một watercourse có thể yêu cầu một giấy phép, vì vậy tham khảo ý kiến tỉnh Nova Scotia của môi trường để được tư vấn.LỢI THẾ-Chịu đựng một số thấm bên nếu một bộ lọc vải được sử dụng bên dưới-Cung cấp một lớp màng linh hoạt-Cung cấp một bề mặt gồ ghề tiêu hao của dòng quân, do đó mini-mizing vấn đề xói mòn-Cung cấp bảo vệ ngay lập tức -Có thể được thành lập cùng với thảm thực vật cho một xuất hiện tự nhiên hơn -Điều chỉnh để thay đổi nhỏ và chuyển động của một ngân hàng stream-Dễ dàng để áp dụng-Có thể được đặt trong tháng mùa đông trên streambanks bởi vì xe tải có thể được thúc đẩy trên đất đông lạnh để các trang web xói mònNhược điểm-Nếu không đúng cách lông, sẽ gây ra một sự thay đổi trong vấn đề xói mòn lên hoặc hạ lưu (trong các ứng dụng streambank)-Cao ban đầu chi phí nếu đá phải kéo bất kỳ khoảng cách-Nên được đặt trên một độ dốc tốt xếp loại không dốc hơn so với 2:1-Rất tốn kém cho một ứng dụng quy mô lớnTHIẾT KẾ CONSIDETARIONSThe ability of riprap to resist erosive forces depends on water velocity and the interrelation of the size, shape, weight, and gradation of the stone, the side slopes, roughness, shape, and alignment of the channel, and the thickness of the riprap layer.The type of stone applied depends on what is most available (quarried stone, field stone, rubble).The stone should be of a blocky, angular shape, rather than elongated, and should be sized of a mixed gradation so that smaller stones fill the voids between the larger ones. A layer of filter stone may be required soil and the size of protective riprap above.DESIGN STEPS1.Select a stable slope for the soil.2.Determine if a seepage drain is required.3.Select the stone size.- Use stream flow velocity ( assuming a graded channel Manning’s roughness of 0.030) to determine suitable stone size.Stream Flw Velocity Mean Stone Diameterm/sec.(ft./sec.) less than 2.0 (6.6)2.0 - 2.5 (6.6 - 8.2)2.5 - 3.0 (8.2 - 9.8)3.0 - 3.5 (9.8 - 11.5) mm (in.)80 -110 (3 - 4)110 - 180 (4 -7)180 - 220 (7 - 8.5)220 - 330 (8.5 - 13)Velocities greater than 3.5 m (11.5 ft.) /sec. Require a more extensive design for steambank protection and should not be attempted without the aid of a soils engineer or other person experienced in the design and installtion of erosion and sediment cotrol measures.-Riprap should be applied at a thickness of at least 1.5 times the maximum stone size and not less than 300 mm (1 ft.) thick.4. Select the filter material, either a geotextile or layer of filter stone, from manufacturer’s liteature or technical references.5. Locate the riprap on the channel bank.- Riprap design on steam channel bends or meanders should not be attempted without the aid of a soils engineer or other person experienced in the design and installation of erosion and sediment control measures.- On sraight channel sections the riprap should protect the bank toe beneath the channel bottom and extend to the top of the bank or at least 600 mm (2 ft.) above the channel design flow water level.- The riprap should not be placed in a manner that would constrict the channel width.IMPLEMENTATION STEPS1.Prepare the site ( after consultation with the Nova Scotia Department of the Environment).- Clear the area of debris.- Grade the banks to the recommendes slope.- Dig out the toe trench.- Install any seepage drains required.2.Place the riprap.- Lay out the filter fabric, if it is being used, or the layer of filter stone.- Riprap can be placed by hand or by machine (backoe, etc.). (Be sure that the stone is not dropped from such a height that it will damage the filter fabric.)-Riprap should be placed tp its full thickness in one operation.- Blend or “ feather” the ends of the riprap section into the upstream and downstream banks so the ends do not protrude into the stream and cause eddying and further bank erosion.-Nếu cài đặt điều kiện mùa đông, riprap nên được một cách cẩn thận đặt và / hoặc chứa để ngăn không cho nó tràn trên băng.3. hoàn thành việc cài đặt.-Một lớp màng thực vật nên được sử dụng trên bất kỳ khu vực mà đã được chấm điểm nhưng không riprapped.BẢO TRÌMột lần, tại chỗ, riprap lót yêu cầu bảo trì ít. Tuy nhiên, bất kỳ trọng lượng rẽ nước đá nên được sửa chữa ngay lập tức.CROSS TÀI LIỆU THAM KHẢO-Trang thông tin 1.3 vải địa kỹ thuật Fiter vải-Trang thông tin 1.5 tình lót & bộ đệm dải-Trang thông tin 2,6 thấm cống