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Vegetation control on embankment dams as a part of remediation work
Published in Jean-Pierre Tournier, Tony Bennett, Johanne Bibeau, Sustainable and Safe Dams Around the World, 2019
L. Demers, S. Doré-Richard, D. Verret
In the permanent work areas, clearing and grubbing of all the vegetation is planned. Clearing is define here as the cut of all the trees and woody vegetation to a maximal height of 150 mm, and grubbing means the removal of all stumps, roots larger than 50 mm in diameter and interwoven roots of smaller diameter after clearing. During grubbing, stumps and root ball will have to be removed by pulling them together, the sides of the cavity created will have to be smoothed to a maximum slope of 1H: 1V and the loose materials will have to be excavated and replaced. At the downstream toe, in the inverted filter and downstream slope stabilization work areas, grubbing should be quite easy considering the uncommon woody vegetation and cavities created by grubbing will have to be backfilled with compacted crushed stones or rockfill. On the upstream part, in the proposed till blanket area, cavities will have to be backfilled with an impervious material if located in the upstream clay core of the existing structure. This part of the work will require special attention from the engineer to verify compliance to dam safety.
Excavations and bulking
Published in Burt G. Look, Earthworks, 2023
Additionally, deep excavations (Figure 8.1-1) require stabilisation of slopes using retention systems. Prior to large-scale excavation, grubbing is performed, with topsoil material stockpiled for later reuse. Transporting, placement, and compaction of the material then follow (Figure 1.4-7).
The Canadian winter road infrastructure in a warming climate: Toward resiliency assessment and resource prioritization
Published in Sustainable and Resilient Infrastructure, 2022
Paul D. Barrette, Yukari Hori, Amy M. Kim
The foundation for over-land winter road segments is the native ground surface (known as the sub-grade). This means it is typically not engineered or modified to any great extent – in places, this may comprise ground striping and grubbing, although that could be only for the first season (i.e. for a new road). The foundation can consist of rock, frozen soil, with or without permafrost depending on latitude. The natural snow cover, which affords a protection for the underlying vegetation, is compacted to smoothen the surface, for instance with a tracked vehicle. It may be overlain with additional snow, or even with artificially-produced ice brought on site with water tankers or from water pulled out directly from a nearby stream or lake. Ice chips can be used and flooded, to help increase ice build-up and thickness. A well-planned route will consider many factors. For example, zones of muskeg, south-facing slopes (more prone to melting due to sun exposure), stream crossings and the presence of boulders can all be a source of problems. For more information, the reader is referred to a number of sources (Adam, 1978; Centre d’enseignement et de recherche forestière, 1998; Duckert et al., 2020; Government of the NWT, 2015; Hori et al., 2018b; Kuloglu et al., 2019; Proskin et al., 2011a).
Fish shoal optimization for identification of the most suitable revetment stone for design of minimum cost earthen canals carrying sediment-laden flow
Published in ISH Journal of Hydraulic Engineering, 2018
Sanjay K. Gupta, Umank Mishra, D. Datta, Vijay P. Singh
Table 3 presents a pair of solutions for each freeboard scenario. These solutions (global leaders) were picked out from the converged shoal, based on the global minimum cost and the lowest sum of all residuals. They emerged out of only angular stone group and did not differ significantly from each other with almost the same costs of construction as well. The same size of stones applied for the revetment of either side slope of a canal caused FSO to yield the zero/negligible shear stress residuals, hence all solutions (see columns 6–7) provided symmetric cross sections for the minimum cost canal. The reason for the best performance of angular riprap stone lies in its ability to remain stable on the steeper side slopes because of the higher mass angle of repose (Gupta and Singh 2012) and interlocking capability that additionally enhances stone particles’ stability on steeper slopes similar to what it does in road pavements. Thus, they afford to sustain even more shear stresses than that induced by the flowing water. This finding is in conformity with the findings of Gupta and Singh (2012) and Gupta et al. (2016). The steeper side slope decreased the top width, hence, the land acquisition cost. The scope of sustaining higher shear stresses by angular riprap stones allowed FSO to proceed further for acquiring higher flow velocity, which, in turn, squeezed the cross-sectional area to reduce the excavation cost as well. Additional benefit arises from the reduction in the cost of clearing, grubbing, moving, and relocation activities because of the reduced land width/right of way. The lesser requirements of earth excavation, land area, and clearing, grubbing, moving, and relocation activities reduce the construction time significantly. Thus, the type of riprap stone used for lining the canal side slopes also plays a vital role to influence the cost, performance, and time of completion of the canal construction project.