Statistical study of the crushing of limestone grains under shearing

Bulletin of Engineering Geology and the Environment - The behavior of granular materials subjected to shear loading is often very complex to be correctly characterized. Loads on a discrete medium...     

Le glissement de terrain d’Ain El Hammam (Algerie): causes et evolution

Some natural slopes are or may become unstable. Instabilities are one of the most difficult problems of engineering geology. The difficulty arises because the estimate of the stability of a site depends on several factors that often interact simultaneously. To better analyze the landslide of Ain El Hammam, these factors were set into two broad categories (passive and active factors). The factors include the liabilities related to geological causes, to the geomorphology and to the hydrology of the site. The structure of the slope is conducive to landslides; the encountered formations are often altered and cracked. They are characterized by a dip and schistosity endorsements favoring the displacement of the layers and also by an alternation of shallow soils and other resistant layers as we go deeper. Tests results show that the geological formations encountered in this area have favorable characteristics to landslides. The mineralogical study shows that the shale rock has reached an advanced weathering and very low content of quartz makes little resistance. The morphological nature of this slope also affects considerably the instability, the steep slope of the site, the nature of the geological formations encountered and the high density of cracks make it vulnerable with regard to this phenomenon. The hydrology has an important role in the erosion and weathering of unstable slopes and on the initiation and activity of the movement. The active factors include climate measures, anthropogenic factors and the effect of seismicity in this region. An important link between the activity of movement and changes in climatic conditions has been observed for this instability. Two basic types of actions have been identified: the action of heavy rainfall and the action of snow cover. Human activity has also contributed to the emergence and evolution of this instability. We have noticed essentially the following effects: the effect of the significant overhead of the head of the unstable slope, the effect of the removal of drainage systems and the role of sewerage not connected flowing directly into the unstable slope. The seismicity of this region also plays an important role and its effects must be evaluated and taken care of in the study of this landslide. The landslide affects a formation of Shale (shale satin) frequently altered and cracked. The structure of this movement and deformation mechanisms induced are very complex. It is a multitude of overlapping and nested ruptures forming a global instability of the slope. Six sliding surfaces were determined on a longitudinal slope (profile EE); some are superficial and others are deep. The observed maximum depth of rupture is greater than 75?m. However, the presence of other sliding surfaces and more complex mechanisms which could not be determined at this stage of the study is not excluded. This shift is characterized by a very active movement extending over a large area and phases of calm and activation (accelerations of movement). The movement is changing both laterally and in depth. Four stages of evolution have been observed for this ground movement (period 1969–2005, the period of 2005–2008, the period from 2008 to April 2009 and the period from May 2009 to March 2011). However, its movement often gives rise to new shallow sliding surfaces (superficial to less deeper) in the basin. Predicting the future behavior of the slope is difficult, the mechanisms are generally poorly known and difficult to understand and model. Knowledge of factors leading to instability is essential in predicting disorders.     

Compaction and shearing behaviour study of recycled aggregates

The aggregates resulting from the recycling of the products of demolition lie within the scope of local materials replacement and this study contributes to their valorisation in the field of the civil engineering, particularly in roads. After having sorted and selected the recycled aggregates, their characterization will bear on the comparison of the physical and mechanical behaviour of the recycled aggregates and natural materials (sand and gravel). In order to study their mechanical response and determine their mechanical characteristics the proctor test, the CBR test and the shearing test have been carried out. The result obtained showed that their characteristics are lower than those of the natural aggregates. Then, we tried to improve them by the following additions (sand, cement and brick). The combination of these materials two to two enabled us to improve some of their physical and mechanical characteristics and bring them near to the natural aggregates. Moreover, repeated shearing of the same sample, in each initial state of stress, highlighted the durability of the aggregates, and particularly their crushing phenomenon.     

Contribution à l’étude du mouvement de terrain de la ville de Tigzirt (Algérie)

This article is a contribution to the study of the causes, characterization, and numerical modeling, using finite elements, of the landslide affecting the coastal slope at the edge of the Mediterranean Sea near the city center of Tigzirt (Algeria). This slope is characterized by a relatively low inclination (13°–15°) and composed of two main geological formations (marly bedrock overlain by recent Quaternary deposits). Several factors have acted jointly and explain the activity of Tigzirt landslide: it is the effect of geological, morphological, and hydrogeological site contexts combined to triggering factors of various origins (human, climatic, and seismic). The landslide is characterized by a planar failure surface, which involves a global translational deformation towards the sea.     

Characterization of the Illilten earth flow (Algeria)

Bulletin of Engineering Geology and the Environment - Located at the summits of the mountains of Djurdjura, the mudflow of Illilten has damaged the two villages, Ait Aïssa Ouyahia and El-Had,...     

Study of the behaviour of schist grains under crushing

Schist is abundant in the Kabylia region of Algeria and hence its use for civil engineering applications, particularly in pavements, is desirable. The paper reports a study on three of the more common schists to determine the characteristics controlling the mechanical behaviour of these materials. The geological and engineering properties of the schists are described and it is concluded that anisotropy is a more important influence than the mineralogy. Of the three schists studied, the harder minerals present in the mottled schist make this the most applicable for use in pavements.