Geotechnical characterization and modelling of the “Fallen Lands” phenomenon in the amazon environment

In many rivers of the Amazon, mainly along the Amazon River, the phenomenon of "fallen land" occurs at the time of the rivers' ebb, causing the erosion of river banks, resulting in major social and economic problems. The influence of saturation/percolation of soil layers on the shear resistance of the affected massifs is unknown. Thus, the main objective of the characterization and geotechnical modelling of these slopes is to determine the shear strength of the affected massifs. For this purpose, deformed and undeformed samples were collected from the various layers of the soil massif in a location where the phenomenon was under development. These samples were characterized physically, chemically, and mechanically. Subsequently, the massifs were recreated in reduced scale models, observing the critical conditions in which the disaster occurred, and qualitatively comparing them with slope stability computational models. The results showed that the layers are classified as silty and sandy soils, with a small fraction of clay, and that there are three types of movements associated with the fallen soils: the fall, overturning, and rotational landslide, all actively influenced by the effects of the river's ebb, saturation/percolation, and texture.

K-means Based Soil Classification System Applicable to a Brazilian Mineral Province

This article presents a geotechnical soil classification system proposed for application on soils of a tropical mineral province, located in Minas Gerais state, Brazil. The system was constructed using data mining techniques, i.e., principal component analysis and k-means cluster analysis, which were applied to a dataset composed of 101 geotechnical characterization laboratory test results of soils from the Province of Quadrilátero Ferrífero. The main objective of the proposed soil classification method was to establish a regional soil classification system, which encompass the interpretability of the main geotechnical parameters of soils by means of the classification, given the little explanatory capacity of the Unified Soil Classification System classification system for the performance of such task. It was possible to establish a chart for soil classification capable of explaining 81.68% of the variability of the analyzed parameters, being established the soil classes A, B and C for the studied soils.

Analysis of the ratio between the plasticity of clay and the expansion capacity by changes in humidity and temperature

Clay is a cohesive material that varies in volume due to changes in humidity and temperature. Its behavior is studied with physical and geotechnical characterization of the material. The experimental analysis of the expansiveness of clays is related to plasticity, which depends on the expansive minerals it contains. The objective is to analyze the relationship between the plasticity index and the expansion capacity due to changes in humidity and temperature; various types of clay from San José de Cúcuta, Colombia, were studied. Liquid limit and plastic limit were analyzed with which the plasticity index was determined. The test tube free expansion and calcination were carried out at 1000 °C to determine the volumetric change due to humidity and temperature, respectively. The clays with plasticity index of 10% - 20% presented expansion by humidity of 5% - 10% and by calcination of 0% - 10%, which indicates low expansion; while the clay with plasticity index of 20% - 40% presented expansion by moisture of 20% - 50% and by calcination of 25% - 50%, which indicates moderately high expansion. The results show that there is a relationship between plasticity index and the expansion capacity due to changes in humidity and temperature.

Geotechnical characterization of soils in the northern zone of Brazzaville

The geotechnical classification of soils by laboratory tests is usually used to determine the class of the soil under study for its subsequent use in construction projects. The interest is certainly well displayed. Indeed, an experimental program has been developed with the aim of studying the soil in the study area. To this end, oedometric and shear tests were carried out on several soil samples in the laboratory. This made it possible to understand the “stress-strain” behavior of these soils. As a result, the presence of a silty sand soil was found that is susceptible to collapse.

Geotechnical characterization of Beka-Gotto rock massif (Adamawa Region-Cameroon) for the use in civil engineering

Beka-Gotto is a village of Ngaoundal located in the Adamawa region (Cameroon). The present study is carried out to determine the physical and mechanical characteristics of the local rock massifs, in order to determine their possible uses in various fields of civil engineering. The methodology used consists of petrographic and geotechnical characterization of the different massifs. The rocks crop outas domes or slabs. The rock is light gray. Under the microscope, the rock presents a grainy microstructure composed of plagioclase, potassium feldspar, biotite and quartz. Zircon and opaque minerals represent the accessory phase. With this composition, rock is granodiorite. The geotechnical study, on the other hand, made it possible to understand that, on the physical level, the rock massif has very good properties. In fact, the specific weight on class 6/10 and 10/14 obtained has mean values of ​​2.73 and 2.68 kN/m3 respectively. While the apparent density obtained of the class 6/10 and 10/14 has mean values 1.35 and 1.46 g/cm3 respectively. Mechanically, Los Angeles coefficient is 24-46.3% while the Micro-Deval coefficient is 7-35% and the coefficient of dynamic fragmentation is 18-30%. In accordance with geotechnical standards, with the exception of the Gbago massif, the other massifs have a choc resistance and a wear resistance of satisfactory to limited grade as well as good resistance to dynamic fragmentation and therefore usable in any type of structure.