Hydraulic Structures: Fourth Edition

A specification for field compaction of earthfill must ensure that a dry density is attained which will ensure strength and othe ...

Table 2.3 Illustrative engineering properties for selected soil types (compare with Table 2.6)Descriptive Saturated Shear streng ...

Care must be taken in the interpretation of Table 2.3, as the meas- ured properties of notionally homogeneous and uniform soils ...

Shear strength is enhanced by increased suction, i.e. a lower degree of saturation, on account of the stabilizing influence of t ...

2.4 Principles of embankment dam design 2.4.1 Types and key elements In its simplest and oldest form the embankment dam was cons ...

Moffat (2002), as there are many such dams in service. The slender core can prove vulnerable to fracturing and internal erosion ...

2.4.2 Defect mechanisms, failure modes and design principles The principal defect mechanisms and failure modes identifiable with ...

result of long-term deformation and settlement. The internal erosion and overtopping mechanisms are of particular concern, each ...

Table 2.4 Embankment dam defect mechanisms and preventive measuresDefect Characteristics Causes Preventive–corrective measures E ...

InstabilityFoundation slip Surface displacement of Soft or weak founda- Consolidate soil; drainage; ground near toe of slope tio ...

2.4.3 Design features and practice The considerations summarized in Section 2.4.2 have major implications with regard to certain ...

A nominal hydraulic gradient through the core of the order of 1.5–2.5 is satisfactory; a value greater than 3.5–4 is undesirabl ...

(d) Foundation seepage control Seepage flows and pressure within the foundation are controlled by cut- offs and by drainage. Cut ...

under the downstream shoulder. This is frequently supplemented by deep relief wells under or near the toe. Both drainage feature ...

(e) Outlet works: tunnels and culverts Outlet works (see also Section 4.8) should where practicable be con- structed as a tunnel ...

erosion protection at the interface between under-layer and embank- ment fill; separation, to prevent the protection layer pene ...

The overall minimum thickness specified for the rock armour layer is determined by two requirements: layer thickness, normal to ...

(g) Embankment crest The crest should have a width of not less than 5 m, and should carry a sur- faced and well-drained access r ...

Table 2.5 Characteristics of core soilsSoil description Cracking resistance Erosion–piping Optimum compaction Sensitivity to (BS ...

Table 2.6 Indicative engineering properties for compacted earthfills (compare with Table 2.3)Fill type Compaction Shear strength ...