Granular materials forming part of civil engineering structures such as rockfill dams and the granular base in pavement systems are subjected to large compressive stresses resulting from gravity and traffic loads respectively. As a result of these compressive stresses, the granular materials break into pieces of different sizes. The size distribution of the broken granular material has been found to be fractal in nature. However, there is no explanation to date about the mechanisms that cause the granular materials to develop a fractal size distribution. In the present study, a compression test designed to crush granular materials is presented. The tests used 5 mm glass beads and a plexiglass cylinder having an internal diameter equal to 5 cm. As a result of compression in the cylinder, the glass beads broke into pieces that had a fractal size distribution. The compression test was numerically simulated using the Discrete Element Method (DEM). The DEM simulation indicated that the particles developed a network of force chains in order to resist the compressive stress. These force chains did not have a uniform intensity but was found to vary widely through out the sample. Also, the distribution of the force chains in the sample did not involve all the grains but only a selective number of them. Thus, the force chains did not cover the whole sample. Using the box method, it was determined that the distribution of the force chains in the sample was fractal in nature. Also, the intensity of the force chains in the sample was found to be fractal in nature. Thus, the fractal nature of the intensity of the force chains and their distribution were found to be the main reason why granular material develop fractal fragments as a result of compression.

When a heap or pile of granular material accumulates at the toe of a failed slope, the pile rests at its angle of repose. The gradual build up of a heap of soil in the laboratory simulates the formation of the heap at the toe of a slope. In this study, the angle of repose developed by binary granular mixtures of coarse sand (1.16 mm in average diameter) and fine sand (0.10 mm in average diameter) was measured in the laboratory. The influence on the angle of repose by the roughness of the base on which the mixtures were placed was also investigated. When the mixtures were placed on a rough surface, the heap developed its angle of repose by two different modes of failure. When the mixtures were controlled by the coarse sand fraction, failure took place on a layer located at the free surface of the heap. When the fine sand fraction controlled the composition of the mixture, the heap developed its angle of repose after the material failed by lateral spreading. When the mixture was placed on a smooth surface, the heap developed its angle of repose by a single mode of failure, namely lateral spreading at the interface of the mixture and the smooth base. A theoretical analysis relating the angle of repose, the internal angle friction of the mixtures, and the interface basal friction angle is also presented.Key words: angle of repose, binary granular material, quartz sand, angle of internal friction, interface friction angle, Rankine earth pressure theory.

No abstract

No abstract

PurposeThis paper aims to document a case study of a disaster in Bangladesh and the role of an information management system for disaster management planning.Design/methodology/approachThe paper uses a methodology that considers perceptions or constructions – including the role of information systems – to be dependent on the social and cultural structures, which is helpful in reducing destruction in disaster‐prone areas.FindingsAdvances in information technology in the form of the internet, geographic information systems (GIS), remote sensing, satellite communication, etc. are beneficial in many aspects of the planning and implementation of hazard reduction arrangements.Research limitations/implicationsNatural disasters strike countries, both developed and developing, cause enormous destruction and create human suffering, and have negative impacts on national economies. Bangladesh suffers regularly and frequently from disasters like floods, cyclone storms, tidal surges, river bank erosion and earthquakes.Practical implicationsIncorporating knowledge of information management system is becoming increasingly important in the derivation of management solutions for disasters.Originality/valueInformation systems including GIS, communication technology, other information retrieval and information management systems should be maintained during natural disasters to reduce the cost and time for contingency. In this paper, an attempt is made to highlight the role of information technology in the management of natural disasters in Bangladesh.