The recent research by scientists has shone a light on the significant impact of the shape of sand grains in relation to the liquefaction potential of granular soils. This potential is directly connected to the strength and stiffness of soil and how earthquakes or similar rapid loading can decrease these cohesive forces, leading to the collapse of structures on the affected ground.
Findings of the Study
The study found a significant connection between the shape of sand grains and their potential for liquefaction. This relationship is an important factor in the collapse of structures during seismic activities. The examinations used in the research revealed that glass beads, with their regular shape and high levels of roundness and sphericity, were likely to liquefy first, followed by river sand and then manufactured sand, both falling at different places in terms of roundness and sphericity. The research suggested that natural sand used in things like slopes and retaining walls could be replaced with irregular manufactured sand to improve both stability and sustainability.
The Role of Irregular Grain Shape in Stability and Sustainability
The irregular shape of sand grains requires more shear force to break the inter-particle locking, enhancing stability. When the shape of the particles becomes irregular, interlocking happens during shearing, offering additional resistance to shear and reducing the chances of particle separation and floating in fluid. Furthermore, irregular shapes increase the deviation in the fluid path, hindering water flow through the pore network and minimizing the likelihood of water separating the particles and causing structural collapse.
Understanding Earthquakes
An earthquake is a natural event involving the shaking of the earth due to the release of energy. This energy generates waves that travel in every direction. The resulting vibrations, known as seismic waves, move through the Earth and are recorded on instruments known as seismographs. The starting point of the earthquake below the surface of the Earth is named the hypocenter, while the corresponding location on the surface is the epicenter. Earthquakes can be classified into different types like fault zones, tectonic earthquakes, volcanic earthquakes, and human-induced earthquakes.
Impact of Sand Mining on Riverbeds
Sand mining refers to the extraction process of sand from river beds or coastal regions. Over-mining can lead to decreased water flow in rivers, thus lowering the water table. Excessive sand mining also results in the pollution of river water. The high metal oxide content and its mixing in river water escalate the Biological Oxygen Demand (BOD), reducing oxygen levels and increasing groundwater pollution. However, contrary to what might be expected, this process actually increases the salinity of the water instead of decreasing it due to the presence of increased metal oxides. These consequences need to be considered when regulating sand mining practices.
