Volumen 35 (2013): Heft 4 (December 2013)

The paper deals with the methodology of performing and interpretation of seismic cone penetration test (SCPT). This type of test is used to determine velocity of the seismic wave in the soil medium. This study is focused on shear wave. The wave is triggered on the ground surface by hitting an anvil with a sledgehammer. Then, vibrations induced at different depths are measured. Based on recorded measurements wave velocity (Vs) and thus also small strain shear modulus Gmax may be calculated. An interpretation of exemplary seismic test results is presented. Crossover and cross-correlation methods are discussed and another, more adequate one is featured and then applied in the interpretation example. Conditions for correct test performance and interpretation are discussed.

It has recently been shown (Arroyo et al. [1]) that 3D DEM models are able to reproduce with reasonable accuracy the macroscopic response of CPT performed in calibration chambers filled with sand. However, the cost of each simulation is an important factor. Hence, to achieve manageable simulation times the discrete material representing the sand was scaled up to sizes that were more typical of gravel than sand. A side effect of the scaled-up discrete material size employed in the model was an increased fluctuation of the macro-response that can be filtered away to observe a macroscopic steady-state cone resistance. That observation is the starting point of this communication, where a series of simulations in which the size ratio between penetrometer and particles is varied are systematically analyzed. A micromechanical analysis of the penetrometer-particle interaction is performed. These curves reveal that a steady state is arrived also at the particle-cone contact level. The properties of this dynamic interface are independent of the initial density of the granular material.

The problem of managing the unneeded and unusable materials is a serious challenge for modern societies. The progress of civilization is accompanied by an increase of the human population. This results in a constant increase of waste production. An average EU citizen generates over 500 kg of municipal waste per year, of which less than one third is recycled. The rest is either disposed of in the landfills or incinerated. Every landfill needs to be properly protected by an impermeable barrier - a liner. Its use is necessary to prevent soil and ground water contamination. The protection barrier needs to be implemented both at the bottom and at the top of a landfill. Various geosynthetic materials are utilized for a liner design. Waste disposed of in a landfill creates high embankments with steep slopes. In these conditions, the problem of liner stability arises. The tests, the results of which are presented in this paper, were conducted to analyze the behaviour of several different combinations of geosynthetic materials used for liner design and to calculate the friction angle of the interface between them. A set of combinations, crucial for the stability of a landfill capping system was tested: geomembrane-geospacer, geospacer-geotextile and geotextile-soil. All of the tests were conducted at the LTHE Laboratory at Joseph Fourier University in Grenoble, France

The paper presents numerical calculations of the influence of implementation technology for underpinning the footing on settlement, with the use of finite element method. Three cases of underpinning methods were taken for calculations, depending on the diameter of the jet grouting column and the order of works. The intensity of settlement of the base of the footing foundation is significantly influenced by the growth of Young’s modulus and the jet grouting column with time, until its complete curing and reaching final technological parameters.

One of the most popular types of foundations in layered subsoil with very differentiated soil shear strengths are precast piles. One of the reasons is the fact that we can well control the driving process during the installation of these piles. The principles of the assessment of bearing capacity and settlements of the piles given by Eurocode 7, concentrate on two main methods, i.e., Static Pile Load Tests (SPLT) and Dynamic Driving Analysis (PDA). However, the evaluation of real load-settlement curve for piles being driven in layered subsoil, where noncohesive and cohesive soils occur alternately, is neither easy nor straightforward. In the paper, the results of both SPLT and PDA tests for objects on the highways in Poland are presented. Field investigations carried out at various time points since the installation of piles (from 7 to 90 days) revealed an increase of bearing capacity with time. The reason for this may be a change of the soil state near the piles due to their driving (displacement of piles) as well as a change of microstructure at the contact between soil and pile shaft. The results of load tests were referred to the geotechnical parameters of the subsoil, which was recognized by means of traditional borings and CPTU tests. The results of tests allow phenomena occurring with time to be assessed and bearing capacity of precast piles to be predicted.

In this paper, the thermal instability of compressible Walters’ (Model B′) rotating fluid permeated with suspended particles (fine dust) in porous medium in hydromagnetics is considered. By applying normal mode analysis method, the dispersion relation has been derived and solved analytically. It is observed that the rotation, magnetic field, suspended particles and viscoelasticity introduce oscillatory modes. For stationary convection, Walters’ (Model B′) elastico-viscous fluid behaves like an ordinary Newtonian fluid and it is observed that rotation has stabilizing effect, suspended particles are found to have destabilizing effect on the system, whereas the medium permeability has stabilizing or destabilizing effect on the system under certain conditions. The magnetic field has destabilizing effect in the absence of rotation, whereas in the presence of rotation, magnetic field has stabilizing or destabilizing effect under certain conditions