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Market Research Group

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Isaiah Moore
Isaiah Moore

Earth And Earth Rock Dams Sherard

Design considerations 2.Failures and damages 3.Measurements of movements and pore water pressures 4.Explorations for fonundations and embankment construction materials 5.Theoretical seepage analysis 6.Earth dams on pervious soil foundations 7.Stability analyses 8.Special design problems and details 9.Dams with impervooooious membranes of reinforced caoncrete, strel plate and asphaltic concrete 10.Treatment of rock foundations 11.Embankment construction

earth and earth rock dams sherard

However, despite the great success of extra-high CFRDs, advanced techniques based on modern science have still not been rooted out, e.g., computer-aided numerical analyses and large-scale model test. In the former, current constitutive models are incapable of representing complete behaviours of rockfills and their highly variable characteristics [4,5,6,7,8]. While in the latter, real conditions could never be fully modeled due to the inherent size effect and distorted boundary conditions [9]. Therefore, the practices of higher and higher CFRDs still relies predominantly on past experience, engineering judgement and empirical methods [10]. In this regard, real field data on the dam performances serves as the most important information that contributes the progress of high CFRDs practice. They can be applied, for example, to (1) verification of the numerical analysis methods and model test protocols; (2) refinement of the empirical approaches with increasing volume of dataset; (3) improvement of the early warning signals for any catastrophic collapse and local incidents in existing dams; and (4) optimization of the field practices for dams under construction. Unlike other infrastructures, a dam constructed at a specific site usually behaves uniquely, characterised by its own materials and construction environments. Thus, data gathered at early construction stages of a dam, instead of from other dams, are most reliable for guiding the practices in its later stages. This strategy is particularly useful for construction of high dams (which usually takes several years) but has not been well implemented so far. One reason might be due to the incapacity of commonly established instrumentation system to support this strategy.

Recent digital advancements have resulted in several new displacement monitoring equipment that could overcome the limits of conventional instrumentations, e.g., photogrammetry, particle image velocimetry (PIV), unmanned aerial vehicle (UAV) and terrestrial laser scanning (TLS). With these techniques, it is possible to acquire high-resolution data points over a large area of the object surface in a very short time period and without direct contact with the object from which a global displacement map over the field of view could be obtained by an effective data processing algorithm for point clouds. In terms of applicability, photogrammetry and PIV are more applicable for close-range, small-scale measurements (e.g., soil elemental test [14]), while a UAV is adept in long-range, regional-scaled displacement measurements [15]. Comparatively, the TLS, with sufficient accuracy for middle-range, middle-scale measurements, appears to be mostly suited for monitoring the dam. In the past decade, several investigators have illustrated the applicability of TLS for deformation detection of concrete arch-dams (e.g., [16,17,18,19,20,21,22,23]). A few works have been conducted on the application of TLS for monitoring earth/rockfill dams. Berberan et al. [24] have detected noticeable crest settlements of Lapão earth dam (39.5-m high) during its first reservoir filling from TLS data. The authors and his co-workers obtained the post-construction deformation behaviour of a clay-core rockfill dam (240-m high) with the TLS technique [25].

Dispersive clay phenomenon was considered in civil engineering practice in the early 1960s after some failures occurred in earthfill dams in Australia, although it was first observed by agronomists about 100 years ago. In the early 1970s, some physical and chemical tests were adopted for identification of dispersive soils [1], [2], [3]. Dispersive soils are structurally unstable, when immersed in water. Therefore they create serious stability problems for embankment dams that may be very difficult to solve later. Many earth dams have been damaged and collapsed as a result of piping caused by dispersive soils [4]. Piping is the main reason for the damage and collapse of 25% of the 214 earth dams that collapsed between 1885 and 1951 [5].


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