Earth and Earth-rock Dams Sherard: A Comprehensive Guide to Design and Construction
Earth and earth-rock dams are types of embankment dams that use natural materials, such as soil, gravel, sand, and rock, to form a barrier across a river or a reservoir. They are widely used for various purposes, such as irrigation, water supply, flood control, hydroelectric power generation, and recreation. Earth and earth-rock dams are also relatively cheap and easy to construct compared to other types of dams, such as concrete or steel dams.
earth and earth rock dams sherard
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However, earth and earth-rock dams also pose many engineering problems of design and construction. They require careful site selection, soil investigation, material selection, compaction, drainage, stability analysis, seepage control, erosion protection, and monitoring. They also need to withstand various loads and stresses caused by water pressure, earthquakes, landslides, ice formation, and wave action. Moreover, they are susceptible to failures and damages due to overtopping, cracking, sliding, piping, settlement, and liquefaction.
In this article, we will provide a comprehensive guide to the design and construction of earth and earth-rock dams. We will cover the following topics:
The basic principles and concepts of earth and earth-rock dams
The types and classifications of earth and earth-rock dams
The design considerations and criteria for earth and earth-rock dams
The construction methods and procedures for earth and earth-rock dams
The common failures and damages of earth and earth-rock dams
The preventive measures and remedial actions for earth and earth-rock dams
We will base our guide on the book Earth and Earth-rock Dams: Engineering Problems of Design and Construction by James L. Sherard et al., published by Wiley in 1963. This book is considered one of the classic references on the subject of earth and earth-rock dams. It provides a comprehensive and systematic treatment of the engineering problems of design and construction of earth and earth-rock dams. It also includes many case studies and examples of actual projects from around the world.
The Basic Principles and Concepts of Earth and Earth-rock Dams
Before we dive into the design and construction of earth and earth-rock dams, let us first review some of the basic principles and concepts that govern their behavior and performance. These principles and concepts include the following:
Embankment dams: Earth and earth-rock dams are types of embankment dams, which are structures that use natural materials, such as soil, gravel, sand, and rock, to form a barrier across a river or a reservoir. Embankment dams can be classified into two main types: homogeneous dams, which have a uniform composition throughout; and zoned dams, which have different zones of materials with different properties.
Earth dams: Earth dams are homogeneous or zoned embankment dams that use mainly soil as the construction material. Soil is a natural material that consists of solid particles (such as clay, silt, sand, and gravel) and voids (such as air and water). Soil has various properties that affect its behavior and performance, such as gradation, density, moisture content, porosity, permeability, shear strength, compressibility, and consolidation.
Earth-rock dams: Earth-rock dams are zoned embankment dams that use mainly soil and rock as the construction materials. Rock is a natural material that consists of solid aggregates of minerals (such as quartz, feldspar, calcite, and mica). Rock has various properties that affect its behavior and performance, such as size, shape, texture, density, porosity, permeability, strength, deformability, and durability.
Core: The core is the central zone of a zoned embankment dam that provides the main resistance to seepage. The core is usually made of low permeability material, such as clay or fine-grained soil. The core should have adequate thickness, continuity, stability, and durability to prevent excessive seepage and piping.
Filter: The filter is the zone of a zoned embankment dam that surrounds the core and prevents the migration of fine particles from the core or the adjacent zones. The filter is usually made of high permeability material, such as sand or gravel. The filter should have adequate gradation, thickness, compatibility, and stability to prevent clogging and erosion.
Shell: The shell is the outer zone of a zoned embankment dam that provides the main resistance to external loads. The shell is usually made of high strength material, such as rock or coarse-grained soil. The shell should have adequate thickness, compaction, slope stability, and erosion protection to withstand water pressure, gravity, earthquakes, landslides, ice formation, and wave action.
The Types and Classifications of Earth and Earth-rock Dams
Earth and earth-rock dams are types of embankment dams, which are structures that use natural materials, such as soil, gravel, sand, and rock, to form a barrier across a river or a reservoir. Embankment dams can be classified into two main types: homogeneous dams and zoned dams.
Homogeneous dams: Homogeneous dams have a uniform composition throughout. They are usually made of soil or rockfill, depending on the availability and suitability of the materials. Homogeneous dams are simple and economical to construct, but they require a low permeability foundation and adequate drainage to prevent seepage and piping. Homogeneous dams are suitable for small to medium heights and widths, and for sites with good foundation conditions.
Zoned dams: Zoned dams have different zones of materials with different properties. They usually have a central zone, called the core, made of low permeability material, such as clay or fine-grained soil; and outer zones, called the shells, made of high strength and high permeability material, such as rock or coarse-grained soil. Zoned dams may also have intermediate zones, called the filters, that prevent the migration of fine particles from the core or the adjacent zones. Zoned dams are more complex and expensive to construct, but they can accommodate a high permeability foundation and reduce seepage and piping. Zoned dams are suitable for medium to large heights and widths, and for sites with poor foundation conditions.
Zoned dams can be further classified into two subtypes: earth dams and earth-rock dams.
Earth dams: Earth dams are zoned embankment dams that use mainly soil as the construction material. Soil is a natural material that consists of solid particles (such as clay, silt, sand, and gravel) and voids (such as air and water). Soil has various properties that affect its behavior and performance, such as gradation, density, moisture content, porosity, permeability, shear strength, compressibility, and consolidation. Earth dams are constructed primarily of engineering soils compacted uniformly and intensively in relatively thin layers and at a controlled moisture content.
Earth-rock dams: Earth-rock dams are zoned embankment dams that use mainly soil and rock as the construction materials. Rock is a natural material that consists of solid aggregates of minerals (such as quartz, feldspar, calcite, and mica). Rock has various properties that affect its behavior and performance, such as size, shape, texture, density, porosity, permeability, strength, deformability, and durability. Earth-rock dams are constructed primarily of graded rockfill heavily compacted in relatively thin layers by heavy plant.
The Construction Methods and Procedures for Earth and Earth-rock Dams
The construction of earth and earth-rock dams involves various methods and procedures that aim to ensure the quality, efficiency, and safety of the works. Some of the main construction methods and procedures for earth and earth-rock dams are as follows:
Site preparation: The site preparation for earth and earth-rock dams involves the clearing, stripping, grubbing, and grading of the dam site and reservoir area. The site preparation should remove any vegetation, organic matter, loose soil, debris, or other undesirable materials that may affect the performance of the dam. The site preparation should also provide a smooth and level surface for the placement of the fill materials.
Foundation treatment: The foundation treatment for earth and earth-rock dams involves the improvement of the foundation conditions by various methods, such as excavation, compaction, grouting, drainage, or stabilization. The foundation treatment should provide a strong, stable, and impermeable base for the dam section. The foundation treatment should also prevent any seepage or leakage through the foundation.
Material excavation and transportation: The material excavation and transportation for earth and earth-rock dams involve the extraction and hauling of the natural materials from the borrow areas to the dam site. The material excavation and transportation should provide sufficient quantity and quality of fill materials for the construction of the dam. The material excavation and transportation should also minimize the environmental impacts and costs of the works.
Material placement and compaction: The material placement and compaction for earth and earth-rock dams involve the spreading and densification of the fill materials in layers or lifts on the dam site. The material placement and compaction should provide a uniform and homogeneous distribution of fill materials within each zone of the dam section. The material placement and compaction should also achieve the required density, moisture content, strength, permeability, and deformation characteristics of the fill materials.
Outlet works installation: The outlet works installation for earth and earth-rock dams involve the construction of structures that allow the controlled release of water from the reservoir to downstream areas. The outlet works installation should provide sufficient capacity and reliability of water supply, flood control, power generation, or other purposes. The outlet works installation should also prevent any damage or interference with the dam section.
Erosion protection installation: The erosion protection installation for earth and earth-rock dams involve the construction of measures that prevent or reduce the loss of material from the dam section due to water action. The erosion protection installation should consider both internal and external erosion mechanisms. Internal erosion occurs due to seepage through the dam section or foundation. External erosion occurs due to overtopping or spillway flow over the dam crest or slope.
Conclusion
In this article, we have provided a comprehensive guide to the design and construction of earth and earth-rock dams. We have covered the following topics:
The basic principles and concepts of earth and earth-rock dams
The types and classifications of earth and earth-rock dams
The design considerations and criteria for earth and earth-rock dams
The construction methods and procedures for earth and earth-rock dams
The common failures and damages of earth and earth-rock dams
The preventive measures and remedial actions for earth and earth-rock dams
We have based our guide on the book Earth and Earth-rock Dams: Engineering Problems of Design and Construction by James L. Sherard et al., published by Wiley in 1963. This book is considered one of the classic references on the subject of earth and earth-rock dams. It provides a comprehensive and systematic treatment of the engineering problems of design and construction of earth and earth-rock dams. It also includes many case studies and examples of actual projects from around the world.
We hope you have found this article informative and helpful. If you have any questions or comments, please feel free to contact us. Thank you for reading this article about earth and earth-rock dams. d282676c82
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