Modifications for Optimization the Compaction Quality Control in Core Slate Random Filling Embankments for Linear Infrastructures

The construction of random fillings from the excavation of medium hardness rocks, with high particle sizes, presents limitations in compaction control. This research applies new control techniques with revised test procedures in the construction of the random fillings core, which constitutes the main part of the embankment, with the bigger volume and provides the geotechnical stability to the infrastructure. The maximum layer thickness researched was 800mm. As there are many types of rocks, this research is applied to metamorphic slates. Quality control has been carried out by applying new research associated with the revision of wheel impression test, topographic settlements and plate bearing test (PBT). A statistical analysis of the core of 16 slate random fillings has been carried out, with a total of 2250 in situ determination of density and moisture content, 75 wheel impression tests, 75 topographic settlement control and 75 PBT. The strong associations found between different tests have allowed to simplify the quality control.

Design of the A1-M1 link road extradosed bridge in Mauritius

<p>The A1-M1 Link Road is a 1 km highway project, currently under construction in Mauritius. The project will cross the Grand River North West Valley, a 90 m deep gorge, with a 3-span extradosed bridge.</p><p>The island of Mauritius is subject to major cyclonic winds and the gorge being crossed needed to be adequately accounted for when assessing the wind effect on the bridge. A detailed wind climate study of the project site was conducted to derive wind buffeting loads for the design of the bridge.</p><p>In addition, particular geotechnical stability issues encountered at the cliffs on either side of the gorge, dictated a non-optimum span distribution which required a complex arrangement of temporary stay cables.</p><p>When complete, the bridge will be a key component of the A1-M1 Link Road Project and will link the existing A1 Road and M1 Motorway, improving connectivity on the West Coast of the Island.</p>

SIMULATION AND BIFURCATION ANALYSIS OF GEOTECHNICAL SYSTEM STABILITY UNDER VIBRATION

The automation of control processes for the stability of geotechnical systems is a great challenge involving the development of methods for multivariate analyzing and forecasting the stability with the subject to the nonlinearity of material stiffness parameters. The aim of the study is to improve the efficiency of automated control systems for geotechnical stability by developing an approach to detect negative changes in bifurcation diagrams of vibration displacement parameters of object structures. The authors present a mathematical model of the dynamic behavior of structural elements of an object as an elementary unit of a geotechnical system that describes a response to an external vibration action. An algorithm of bifurcation analysis is presented, which allows authors to determine the initial transition stage of the object structure to an unstable state by the acceleration values of forced oscillations exceeding the model parameters. A bifurcation diagram of stability changes in the structure of object at the displacement resulting from the load increase under vibration action has been constructed. This diagram, which type of codimension-one bifurcations is merging, enabled to determine the critical load values resulting in an unstable state transition of a system due to the influence of a combination of vibration factors. The efficiency evaluation of the proposed approach was carried out by the comparison with the results of construction stability calculations obtained by the use of the dynamic coefficient. The difference between the values of the maximum object displacement without loss of the stability under vibration action, obtained by the standard calculation method and using the developed model, is 32.5%, and it is significant in the theory of structure stability. When exogenous vibration noise is used as a source of a sounding signal, the application of the developed approach in automated control systems for geotechnical stability enable to change the permissible stability thresholds of objects being exploited depending on the level and combination of influencing factors.

Study of the geometrical and the geotechnical stability of the concrete lozenges channels

Several methods are proposed for improving the slopes stability. We are studying the use of a new technique: concrete lozenges channels. The objective of this technique is to stabilize the slope against water erosion. In addition, it makes it possible to combine both mechanical protection with concrete lozenges channels and protection by plant engineering techniques with plants adapted to the area. The present study is part of the continuation of a parametric study whose purpose was to define the optimal design of concrete lozenges channels. Using the finite element method, the purpose is to study the geotechnical stability of a slope stabilized by said lozenges and to define their constructive arrangements.