高清福利片

After thousands of years constructing massive buildings and monuments you would imagine scientists understood the behaviour of the ground we stand on.

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鈥淥ur safety could be dependent on understanding the behaviour of just a few grains of sand,鈥� says Wang.

鈥淢y research examines how soils respond under extreme conditions, such as earthquake, especially when this behavior is further complicated by the introduction of pore water.

Wang says soil strength can change under impacts from sources including heavy machinery operation, pile driving, explosions or earthquakes. This could have disastrous consequences such as the manifestation of soil liquefaction.

鈥淟iquefaction is when wet soils completely lose their strength because of an excessive build-up of water pressure due to the ground shaking,鈥� he explains.

鈥淭he 2011 Christchurch earthquake in New Zealand produced this type of phenomenon. The entire city saw widespread damage resulting from massive amounts of soil liquefaction.

鈥淪o it makes sense to avoid constructing buildings on ground with extensively saturated soil prone to liquefaction, or you must have plans for soil remediation such as draining the ground.

鈥淏y adequately understanding the liquefaction potential of soils when planning cities and suburbs, we will know exactly where and where not to construct our facilities and place our most critical infrastructure.

鈥淭his could potentially save lives and billions of dollars in repair costs,鈥� he says.

A motivator for Wang鈥檚 research is his Wellington earthquake experience.

鈥淚 was on the 9th floor of the building at that time,鈥� he says. 鈥淎ll of a sudden, the building swayed from side to side. I saw walls crack and books fall from the shelves. It was like drifting on a boat.鈥�

The unnerving experience became the catalyst that encouraged him to pursue his earthquake-related research in Australia.

鈥淚 take a small soil sample and place it into a machine. I then subject the sample to a sudden impact,鈥� Wang says. 鈥淭his will allow sensors on the machine to feed me information which enables me to calculate the soil鈥檚 strength, or how much load it can support.鈥�

In the experiments, Wang also made decisions about what types of soil to test, how much water to add, and what kinds of impact to subject on the material.

So far, Wang tested three types of porous material and will shortly conduct the final batch of experiments on the fourth.

, Wang鈥檚 PhD supervisor says the team鈥檚 aim is to understand the interaction between water and soil particles and to highlight the need for the consideration of soil liquefaction in the building and design codes of countries with frequent earthquake activities, including China.

Wang鈥檚 research will be first of its kind to systematically investigate the effect of particle size distribution, particle shape and water content on the behaviours of porous media under impact loading.

This research will reveal the key factor that controls the particle-water interaction in wet porous media and thus help engineers understand the physics behind the liquefaction of soil in earthquakes.

Five fun facts about soil and sand听

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• Soil is a living system.听There are more bacteria in a handful of soil than there are people on earth. That鈥檚 over 6 billion!

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• The total number of sand grains on earth is approximately equal to 20 per cent of all the stars among the 200 billion galaxies making up the observable universe.

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• The tallest sandcastle constructed measures 14 metres 鈥� about the height of a four storey building.

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• Up to 50,000 square kilometers of topsoil 鈥� an area around the size of Costa Rica 鈥� is lost every year mainly due to wind and water erosion.

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• Contrary to Hollywood movies, the density of the human body would make it impossible to sink in quicksand. We would actually float.