Mechanical parameters of working platform based on DMT

Nośność platformy roboczej określana jest w sposób analogiczny do nośności podłoża uwarstwionego, w którym warstwa wierzchnia zbudowana z gruntu niespoistego spoczywa na słabonośnym podłożu z gruntu spoistego. Badanie DMT wykorzystano do wyznaczenia parametrów wytrzymałościowych podłoża (kąta tarcia wewnętrznego warstwy górnej i wytrzymałości na ścinanie bez odpływu podłoża słabonośnego) oraz do wyznaczenia modułu odkształcenia gruntu (MDMT). Wyznaczono wartości charakterystyczne poszczególnych parametrów na podstawie wyników z pięciu badań dylatometrycznych na poletku doświadczalnym. Przeanalizowano różne metody oszacowania wartości charakterystycznej parametrów geotechnicznych.Bearing capacity of working platform is determined in a simmilar way as for layered subsoil, where the upper layer from cohesionless soil is resting on soft cohesive strata. DMT test was used to estimate soil strength parameters (angle of internal friction for the upper layer and undrained shear strength of soft subsoil) and constrained modulus MDMT. The characteristic soil parameters were determined with five dilatometer tests on trial field. Different estimation methods of characteristic value of soil parameters were considered

Bearing Capacity of Working Platforms using Distinct Layout Optimization Method

Bearing capacity of the working platforms from sandy soil resting on NCOC clays was analyzed using LimitState GEO program. Different failure modes are considered using distinct layout optimization (DLO) method, which forms the upper bound solution of limit state analysis. Different mechanisms of failure were observed as a function of the platform thickness, angle of internal friction of the platform material and undrained shear strength of the subgrade. The distribution of undrained shear strength with depth was also taken into consideration. The typical failure modes were presented. The calculated bearing capacity was compared to analytical solutions and recommendations of BRE. Special attention was paid to the platform resting on soft clay with undrained shear strength lower than 20 kPa, as this case is not covered by these recommendations. The solution obtained with DLO method was compared to bearing capacity calculation using Plaxis and φ, c reduction method. Additionally some analysis were performed for a real platform of sandy soil on the soft organic clay. Here, the strength and deformation parameters of the platform material and the subgrade were determined with dilatometer test (DMT). This kind of approach permits to determine both strength and deformation parameters of the platform material and soft subgrade in one test

STRENGTH CHARACTERISTICS OF TYRE CHIPS-SAND MIXTURES

International audienceWaste tyres are more and more widely used for geotechnical applications as backfill material that is either a substitute for natural soils or combined with them. Beyond the economical and environmental concern, these materials can help solving problems with low shear strength soils. This study aims at investigating a mechanical behaviour of tyre chip-sand mixtures thanks to a triaxial tests campaign. Two factors were studied: (i) the tyre chip content, from 0 to 100% by mass and (ii) the orientation of the pieces of tyre, with four varying orientation conditions. This paper focuses on the stress-strain behaviour of the different mixtures and their volumetric variation during the tests. The angle of friction and cohesion for each mixture are presented. The optimum percentage mass and optimum unit weight, which gives the maximum shear strength, are also determined. The influence of the different parameters is discussed