Laboratory Investigation and Numerical Modelling of Soil Improvement Techniques
A discussion is presented of the use of the laboratory investigation and of the finite element modelling for the analysis of geotechnical problems involving techniques of soil improvements. Among the variety of possible applications, those related to the
- PDF / 3,832,164 Bytes
- 32 Pages / 481.89 x 691.654 pts Page_size
- 41 Downloads / 185 Views
Abstract: A discussion is presented of the use of the laboratory investigation and of the finite element modelling for the analysis of geotechnical problems involving techniques of soil improvements. Among the variety of possible applications, those related to the low pressure grouting of granular soils, to the artificial freezing of grounds and to reinforced earth structures are discussed in some details. The analyses of cases related to actual design problems are also presented and commented upon.
1 Introduction The use of particular techniques aimed at improving the mechanical, or hydraulic, characteristics of soil or rock masses is nowadays a common practice in geotechnical engineering. Treatments of this kind have been known, and applied, since ancient times. For instance, layers of cohesive soil reinforced with mats of vegetable fibres were used in Mesopotamia for the construction of temples, or Ziqqurat, since the XXII century BC. The tower of Babel, described in the Bible, is believed to be an example of them. These techniques, whose range of applications dramatically increased with the developments of modem technology, can be subdivided into two main categories depending on their temporary or permanent effects. Among the temporary ones the electro-osmosis, the artificial ground freezing, the temporary lowering of the water table by pumping wells, etc. can be mentioned. Among those that lead to permanent improvements of the characteristics of the geotechnical medium, the most popular ones are the deep and shallow compaction, the permanent drainage systems, the low and high pressure grouting, the soil pre-loading, the reinforced earth, the thermal treatments, etc. The design of relevant geotechnical works involving these techniques requires a proper modelling, either physical or numerical, of the improvement process and/or of the subsequent behaviour of the treated soil. In fact, because of their intrinsic limits, closed form analytical solutions can hardly provide an adequate insight into these complex problems. Here the discussion is focused on the numerical modelling, through the finite element method, of the following well-established procedures for soil improvement: the low pressure grouting of granular soils, the artificial freezing of saturated soils and the so-called earth reinforced structures. From the computational mechanics standpoint, the analysis of the mentioned improvement techniques involves various relevant aspects. They are related, in particular, to the solution of elasto-plastic (strain softening) problems, to the analysis of seepage and consolidation, to the
V. D. Griffiths et al. (eds.), Advanced Numerical Applications and Plasticity in Geomechanics © Springer-Verlag Wien 2001
26
A. Cividini
non-linear transfer of heat and to the use of homogenisation procedures for the analysis of inhomogeneous, non-isotropic materials. In the following, the main characteristics of the finite element analysis of the mentioned problems are presented, as well as some applications to practical case
Data Loading...
