- Détails du magazine
- Première publication
- 09 Nov 2012
- Période de publication
- 4 fois par an
- Accès libre
Pages: 3 - 17
The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.
- Accès libre
Pages: 19 - 37
Issues concerning protection of buildings against the impact of underground coal mining pose significant scientific and engineering challenges. In Poland, where mining is a potent and prominent industry assuring domestic energy security, regions within reach of mining influences are plenty. Moreover, due to their industrial character they are also densely built-up areas. Because minerals have been extracted on an industrial scale in majority of those areas for many years, the rock mass structure has been significantly disturbed. Hence, exploitation of successive layers of multi-seam deposits might cause considerable damage - both in terms of surface and existing infrastructure networks. In the light of those facts, the means of mining and building prevention have to be improved on a regular basis. Moreover, they have to be underpinned by reliable analyses holistically capturing the comprehensive picture of the mining, geotechnical and constructional situation of structures. Scientific research conducted based on observations and measurements of mining-induced strain in buildings is deployed to do just that.
Presented in this paper examples of damage sustained by buildings armed with protection against mining influences give an account of impact the mining exploitation in disturbed rock mass can have. This paper is based on analyses of mining damage to church and Nursing Home owned by Evangelical Augsburg Parish in Bytom-Miechowice. Neighbouring buildings differ in the date they were built, construction, building technology, geometry of the building body and fitted protection against mining damage. Both the buildings, however, have sustained lately significant deformation and damage caused by repeated mining exploitation.
Selected damage has been discussed hereunder. The structures have been characterised, their current situation and mining history have been outlined, which have taken their toll on character and magnitude of damage. Description has been supplemented with photographic documentation.
- Accès libre
Pages: 39 - 48
Application of the pile joining is a new solution of the complex pile foundation including the base, made in the ground, and the piles joining the base with the girt. This kind of piles can be used for foundation under special geological conditions (proglacial stream valleys) for foundation reinforcement of the existing buildings and new foundations. The solution proposed may be used in the swelling soils. In this work, the possibilities of applying joining piles in different soils, like fine sands, silts, clays, clay shale, sandstones, which can be the foundation for the pales have been considered.
- Accès libre
ANALYTICAL VERIFICATION OF OUTLET DEVICES CAPACITY OF LUBACHÓW STORAGE RESERVOIR ON THE BYSTRZYCA RIVER
Pages: 49 - 66
The Lubachów storage reservoir was built in the 1920’s. It is equipped with a relatively complex outlet installation, operating in variable hydraulic regime. The discharge deviations curves elaborated by German engineers for individual devices, after verification turned out to be burdened with a comparatively big error. This concerns especially the front spillway as well as intermediate outlets, and to a smaller degree the bottom outlets. The authors made a detailed analytical verification of the outlet installations and found great deviations from the currently valid discharge curves for these devices. Based on the analysis of conditions of computational discharges passage through the reservoir, they proved a high potential threat of water flow over the dam crest.
- Accès libre
Pages: 67 - 81
In the paper, a numerical study of the size of representative volume element for the linear elasticity problem is performed. The calculations are carried out for three different types of random microstructures: checkerboard, the Ising model microstructure and Debye microstructure. It is postulated and then verified that there exists a relation between the morphology of microstructure contained in the lineal-path function and the minimum RVE size. It is confirmed, on the basis of numerical examples, that for all the microstructures considered the largest lineal-path can be treated as the size of RVE
- Accès libre
Pages: 83 - 96
This article presents the results of numerical calculations of drainage of a large engineering construction - “Afrykarium” in Wrocław ZOO, Poland, based on a 2D numerical model for seepage flow. In the numerical simulations the real (natural) hydrogeological conditions, water-courses, surface reservoirs and time dependent seepage flow (during drainage) are taken into account. The aim of numerical calculations was to determine quantities (draining time, number of wells, spacing and arrangement of wells, flows for every well, and hydraulic head map) necessary to design an effective drainage system of construction site. The mathematical model adopted to illustrate and predict groundwater depression during pumping was the Boussinesq equation for unsteady 2D flow.