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External ground support
Published in M.L. Jeremic, Ground Mechanics in Hard Rock Mining, 2020
This is an expensive method with low productivity and only used in high grade ore for maximum recovery. ‘Head-cover’ is provided by 2.75 m planks. The square set mining method has generally been converted to the cut-and-fill system. Timber roofing is used for the undercut-and-fill method, which consumes a high proportion of current underground timber requirements. Spruce planks are used to construct six piece laminated stringers which support a mat of round lagging beneath the cement tailings fill. As these stringers are exposed by mining the ore beneath this mat, they are supported at 1.8 m intervals by pine or spruce stull posts (Figure 10.1.9). This use of timber is not directly for ground support but to support the fill and to maintain the temporary opening required for the removal of broken ore.Auxiliary timber is not directly connected with ground support, but it is used to build fill fences, travelways, manways, chutes (Figure 13.2.9), fill bulkheads, and various other construction purposes.
Usage requirements for antique wooden floors in the context of their conservation
Published in Koen Van Balen, Els Verstrynge, Structural Analysis of Historical Constructions: Anamnesis, Diagnosis, Therapy, Controls, 2016
A. Rozanska, A. Policinska-Serwa
the planned thermal and acoustic insulation, in order to ensure a gap for ventilation. Manuals from the 1930s proposed to place joists every 450 mm if the blind floor was 25 mm thick; every 650 mm if it was made of planks that were 33 mm thick; and every 800 mm, if the planks were 38 mm thick. Between the joists and the blind floor we can put some technical felt or a dilating edge tape made of polyethylene foam, which prevents the wood from creaking. If a blind floor is planned under the floor, then it should be made of strength sorted pine wood planks that have been planed and do not have any wanes. The joints between planks should be made only above the joists, using dowel type fasteners that fulfill the requirements of the EN 14592 standard. The thickness of planks as well as the amount and type of joints have to be specified on the basis of resistance calculations in line with EN 1995-1-1 or tests carried out in accordance with EN 1195 and EN 12871. Instead of planks, floor decking can be made of engineered wood panels, under the condition that they meet the requirements of EN 13986, have a CE mark and are specifically dedicated for construction applications in floor decking - which must be written in the usage properties declaration and, usually, marked with a specific word written on the panel: "floors". During repairs, special attention should be paid to making proper insulation against humidity, always between the brick base and the wooden element. The layer or layers of insulation - usually made of tar paper - can only be glued to a base that has been covered with a primer. It should be stressed that the humidity of the base below the layer of insulation, as well as of the building walls should not exceed 2%, while between the joists and the wall there should be an air gap, at least 20 mm wide. The loads can also be transferred through another structural element - a solid base, usually (in case of contemporary floors) made of concrete or screed. The mineral subfloors are made of crushed stone and a binding agent (cement/anhydrite), in the proportion that is in line with the recipe indicated for a given compressive strength, or a ready mix whose properties are declared by the manufacturer, in accordance with the EN 13813 and EN 13318 standards. A hardened subfloor made in accordance with the recipe and the technological requirements should have the declared compressive and bending strength assumed by the designer. The strength values of a hardened subfloor can be verified, for example, with the test methods described in EN 13892-2 and EN 13892-1. In case of parquets made of wood or engineered wood materials not glued to the subfloor (floating parquets) the usual subfloor resistance is at least C12. C20, C25 and C30 subfloors or subfloors with higher requirements designed individually, e.g. with rebars, are used under wooden floor parquets glued to the subfloor. The type and distances between rebars should be specified in the construction design. The
How well is the basin plan meeting its objectives? From the perspective of the Coorong, a sentinel of change in the Murray-Darling Basin
Published in Australasian Journal of Water Resources, 2023
Justin D. Brookes, Brendan Busch, Phill Cassey, Daniel Chilton, Sabine Dittmann, Tyler Dornan, George Giatas, Bronwyn M. Gillanders, Matt Hipsey, Peisheng Huang, Christopher Keneally, Micha V. Jackson, Luke Mosley, Rowan Mott, David Paton, Thomas Prowse, Michelle Waycott, Qifeng Ye, Sherry Zhai, Matthew Gibbs
A key plank in Australian water reform was the establishment of the Commonwealth Environmental Water Holder (CEWH). In consultation with Basin states and other smaller water holders (such as state jurisdictions and The Living Murray), water is allocated and delivered for desired environmental benefits throughout the southern connected basin. Commonwealth environmental water (CEW) represented 76% of the environmental water delivered over the South Australian border over the period from 2014/15 to 2020/21 (Ye et al. 2022). Given the direct relationship with the Basin Plan, and being the largest proportion of environmental water, CEW is the focus of this work. The Basin Plan requires the MDBA to prepare a Basin-wide Environmental Watering Strategy (BEWS) which is to identify specific Basin-wide environmental watering priorities over the long term, help co-ordinate the management of environmental water, including guiding the development of consistent long-term watering plans (Basin Plan 2012) to achieve the environmental objectives of the Basin Plan.
Performance evaluation of a short-distance transition subgrade with pile-plank structures in high-speed railway
Published in International Journal of Rail Transportation, 2023
Shuanglong Li, Limin Wei, Jingtai Niu, Zhiping Deng, Bangbin Wu, Wuwen Qian, Feifei He
Figure 15 shows the peak acceleration distribution of measuring points B-3, P1–3, P1–3, P1–3 and T-3 under different thicknesses of bearing plank. The tp has a certain influence on the dynamic response distribution. With the increase of tp, the acceleration peak on the base slab gradually decreases, indicating that the vibration level has decreased, which is helpful to improve the safety of train operation. However, the excessive thickness of the bearing plank will cause higher engineering costs and more difficult construction technology. Therefore, considering the sensitivity of the bearing plank thickness to the dynamic response of the transition zone, the bearing plank thickness of approximately 1.0 m is recommended.
Effectiveness of various polysaccharides for controlling properties of alkali-activated manganese-rich slag pastes
Published in European Journal of Environmental and Civil Engineering, 2022
Shehzad Mussawar, Muhammad Ali Sikandar, Zafar Baloch, Amjad Naseer, Syed Azmat Ali Shah
With increasing environmental awareness, the use of naturally derived and eco-friendly products in the construction industry is trending worldwide. Plank (2004) referred to the 20th century as the ‘age of admixture’, predicting that the demand for bio-admixtures would increase, particularly for microbial biopolymers, not only because of their ability to improve the properties of concrete materials but also because of the growing trend towards the use of natural precursors and eco-friendly products in building materials. In the 1920s, lignosulfonate—a biopolymer—was used for the first time as a concrete plasticiser. It was the first functional polymer used in large-scale construction (Plank, 2004). The popularity of biopolymers such as starch, xanthan gum, cellulose ethers, and polyaspartic acid as admixtures for improving the properties of cement-based materials has since increased (Ramachandran, 1996). Biopolymers generally impart useful characteristics to cementitious materials, such as plasticising, viscosity enhancement, water retention, shrinkage reduction, and setting retardation. In early 2000, Plank (2005) estimated the annual sales of biopolymer additives on the global construction materials market to be 1 billion USD.