Journal of Geotechnical Geology
Volume:18 Issue: 1, Winter and Spring 2022

Due to the persistent failures of road pavements and scarcity of suitable materials for use as fill for road constructions, geotechnical investigations were conducted to characterize and select suitable sites that subsurface soils can be obtained for road construction purposes in the study area. This involved collection of sixteen soil samples from four selected sites. The geotechnical methods deployed include sieve analysis, liquid limit and plastic limit determinations, compaction tests, and, California Bearing Ratio tests (CBR). The particle size distribution curve (PSD) showed ≤35% passing sieve #200. The liquid limit ranges from 22%-47%, the plastic limit from 14%-31%, and the plasticity index range from 6%-18%. The values of the optimum moisture content using the West African Compaction (OMC-WAS) methods ranged from 6.6%-11.5%, with maximum dry density for WAS (MDD-WAS) from 1862 kg/m3-2061 kg/m3 while the optimum moisture content using the modified AASHTO methods (OMC-MAS) ranged from 7.0%-11.6% and maximum dry density for MAS (MDD-MAS) from 1932 kg/m3-2174 Kg/m3 respectively. CBR for unsoaked soil samples ranged from 100%-249% and for soaked samples, 70%-119% respectively. The soils are classified into three groups based on AASHTO classification as A-2-4, A-2-6, and A-2-7 which classifies the soil as gravelly clayey or silty sand. The site investigated is, therefore recommended suitable site for obtaining good to excellent materials for use as fill (bass and sub-base) materials to enhance quality of road pavement construction in the study area.

Rivers are sensitive to tectonic movements, and there is a close relationship between river landforms and tectonic movements. Morphotectonic indices are used as an instrument to identify new and active structures of these movements. Kesmat catchment is a sub-basin of Dez River, which is located in Lorestan Province with a surface area of 34.33 square kilometers. The aim of this study was to analyze the tectonic activity of Kesmat Basin using topographic map and digital elevation model in the environment of remote sensing software and GIS. In this study, four morphotectonic indices including Stream Length-gradient Index (SL), Index of Drainage Basin Shape (BS), River Sinuosity Index (S) and Drainage Basin Asymmetry Factor (AF) were used, and the results of their analysis were expressed as Index of Active Tectonics (IAT). Based on the findings, the values of 207, 1.09, 1.27 and 66 were obtained for SL, BS,S and AF indices, respectively. The index of active tectonics (IAT) shows that the region has moderate tectonic activity.

The present study studies and evaluates the interactions between the states of structure-soil interaction for strip foundations reinforced with pile pedestals under dynamic loads such as earthquakes. To do this, the first design of strip foundation on sandy soil attempted to understand the geotechnical behavior of foundation under dynamic loading. The strip foundation is a regular procedure used to improve the dynamic response to earthquakes. As a methodology, the finite element method and Plaxis software were used to simulate the displacement and deformation condition of the soil-structure interaction. According to the results, the program was successfully implemented to model the strip reinforced foundations in saturated sandy soil under dynamic loading.

One of the most challenging parts of every project including prefabricated vertical drains (PVDs) with surcharge preloading for ground improvement in construction period is lateral displacements that occur in toe of embankment. In this paper Finite element Geostudio 2018 was used for modeling and verification of the full-scale test embankment which were constructed to study the effectiveness of PVDs combined with surcharge preloading at Bangkok airport. The surcharge preloading was modeled by staged construction using a coupled analysis which gives best results for primary consolidation cases. Different depths were modeled and the results were compared and analyzed. It was shown that by increasing the installation depth of PVDs the lateral displacement increased underneath but lateral displacement at ground surface remain approximately constant. In the case of decreasing PVDs length the lateral displacement remains constant for ground surface and decrease slightly with respect to verified model. Although it should be mentioned that like any geotechnical big scale project because of distinct soil characteristic of clay soils and layers properties of any project, complete investigation and modeling is essential prior to finalizing the ultimate design by competence geotechnical consultants.

This paper presents the development of self-compacting lightweight concrete (SCLC) incorporating pumice. Seven concrete series with water–binder ratios of 0.4 and a constant total binder content of 550 kg/m3 were designed. The pumice was added at proportions corresponding to 5%, 10%, 15%, 20%, 25% and 30% by weight of cement. The performance of mixtures was evaluated by conducting comprehensive series of tests on fresh and hardened properties. Fresh properties of mixtures were assessed by slump flow diameter, T50, V-funnel flow time and L-Box. Also hardened properties were investigated via compressive strength, flexural strength, density and water absorption. The fresh concrete test results revealed that by substituting optimum levels of pumice in SCLC, satisfactory workability and rheological properties can be achieved. 10% pumice significantly enhanced the compressive and flexural strength of SCLC at later ages. The density of the SCLC containing pumice was lower than those of the control SCLC. A lower absorption and permeability can be achieved for mixes especially mixtures incorporating 10% pumice. In general, it seems that 10% pumice can be considered as a suitable replacement regarding to the economic efficiency, fresh and hardened properties. Petrographic examination of concrete samples shows that pumice aggregates are in the range of basalt to basalt andesite and have about 30% porosity. The minerals inside the pumice aggregates include feldspar and hornblende and some quartz, as well as some fine iron oxide minerals.

This study aimed to provide a comprehensive review study of the nanoclay and nanofiber filter application in landfilling stage for solid wastes to control the leachate leakage from landfill liners. The filtering is a key element in landfill liners that prevent the leachate from seepage which is the main factor in groundwater pollution. In this regard, providing new methods that are more adaptable to environmental conditions can be efficient. The presented paper is prepared as a review study on nanotechnology application in geotechnics that is used for preventing leachate leaks from landfills body specifically nanoclay and nanofibers.