Coarse-grained soils are a type of soil frequently found in civil engineering projects. The mechanical characterization of these soils is very difficult because of the presence of large-sized elements that disturb or prevent the realization of the tests. However, there is still no rational procedure to characterize coarse soils and determine their mechanical characteristics (cohesion and friction angle) for the calculation of slope stability or structures. The objectives of the research work are to contribute to the improvement of the knowledge of the mechanical behavior of matrix coarse-grained soils and to propose a rational procedure to characterize them. In order to achieve these objectives, it is important to understand the influence of the fundamental parameters related to the mode of reconstitution on the mechanical behavior of the coarse soils: volume fraction, particle size distribution and spread, consolidation level, and the initial state of the matrix. Tests are carried out using the large-sized triaxial testing device in drained conditions. With natural coarse-grained soils, it is very difficult to conduct repeatability tests to validate the results. For this reason, we will study a particular category of coarse-grained soils composed of inclusions (coarse elements) within a fine sandy matrix (matrix coarse-grained soils), using a reference soil composed of a mix of sand and gravel. The results show that for both states of sand compaction (ID=0.4 and ID = 0.8), the shear strength of the soil increases with the increase in the proportion of gravel. This increase is more marked in the case of uniform 8/10 mm gravel. Thus, the size of inclusions has no significant influence on the value of qmax. Doi: 10.28991/CEJ-2022-08-08-012 Full Text: PDF

The phenomenon of soil liquefaction can be an induced effect of earthquake shaking where the saturated soil loses some or all of its bearing capacity and stiffness. Likewise, the increase of water pressure in the soil pores under the seismic wave causes a decrease of the shear strength. As a result, the soil becomes liquefied and susceptible to producing permanent deformations. The phenomenon of liquefaction is generally unpredictable, and neglecting it can influence the stability of structures and infrastructure foundations. Since the 1964 Alaska and Niigata earthquakes, more research works have been conducted to assess land liquefaction vulnerability. This study is undertaken in this field, whose objective, on the one hand, is to signal the phenomenon of liquefaction in the north of Morocco as a geo-technical part known for its instability and, on the other hand, to study the semi-empirical methods to adequately evaluate the liquefaction potential while specifying the most appropriate method for our case study. Similarly, the study is based on data derived from experimental results of in-situ tests applied to the embankment crossing the valley of "Oued Gharifa" on a high-speed rail line section from KP 228+400 to KP 229+375. Moreover, this research aims to show and discuss the evaluation of liquefaction potential of the experimental results of the CPT (cone penetration test) using three semi-empirical methods, namely the Juang method, the Olsen method, and the Robertson method. In doing so, we are going to compare the application results of the three semi-empirical methods in light of evaluating the liquefaction likelihood of the studied area, taking into account the nature of the soil, the variation of the safety coefficient, and the liquefaction potential for each method as well. Doi: 10.28991/CEJ-2023-09-02-013 Full Text: PDF

Water erosion is a phenomenon that threatens not only agricultural land but also road and rail infrastructure. This article investigates the slope stability against water erosion for five embankments situated on the north axis and east axes of the Moroccan linear railroad infrastructure and proposes the use of concrete lozenges channels for slope erosion protection. Using RUSLE erosion model, the assessment of the sensitivity of these infrastructures to water erosion has enabled us to deduct the essential role of water, the type of soil and the slope inclination in triggering instabilities. The new concrete lozenges channel technique proposed by this paper makes it possible to improve a percentage decrease of the soil loss rate by more than 35%. Indeed, the soil loss rate reduction depends on the concrete lozenges channel number. An increase in this number decreases the soil loss rate. For a study case, the concrete lozenges channels were sized to define the number of lozenges necessary in the vertical and horizontal directions of the slope. Important parameters must be defined for this new technique design, namely, the inclined channel section and the ditch section. In fact, the concrete lozenges channel numbers decrease if the number of ditches and inclined channel sections increases. However, the stability of these drainage structures and the project budget must be studied to find an optimal design that considers the quality-price ratio.

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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.