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Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid.
Use of SPT data for direct prediction of liquefaction potential suffers from roughness of correlations and from the need to "normalize" SPT data to account for overburden pressure, sampling technique, and other factors. [4] Additionally, the method cannot collect accurate data for weak soil layers for several reasons:
Vibro stone columns or aggregate piers are an array of crushed stone pillars placed with a vibrating tool into the soil below a proposed structure. This method of ground improvement is also called vibro replacement. Such techniques increase the load bearing capacity and drainage of the soil while reducing settlement and liquefaction potential ...
If the soil particles in a sample are predominantly in a relatively narrow range of sizes, the sample is uniformly graded. If a soil sample has distinct gaps in the gradation curve, e.g., a mixture of gravel and fine sand, with no coarse sand, the sample may be gap graded. Uniformly graded and gap graded soils are both considered to be poorly ...
Seismic microzonation is defined as the process of subdividing a potential seismic or earthquake prone area into zones with respect to some geological and geophysical characteristics of the sites such as ground shaking, liquefaction susceptibility, landslide and rock fall hazard, earthquake-related flooding, so that seismic hazards at different locations within the area can correctly be ...
Soil is placed into the metal cup (Casagrande cup) portion of the device and a groove is made down at its center with a standardized tool of 2 millimetres (0.079 in) width. The cup is repeatedly dropped 10 mm onto a hard rubber base at a rate of 120 blows per minute, during which the groove closes up gradually as a result of the impact.
The effects of soil liquefaction, seen after 2011 Canterbury earthquake. In geology, soil liquefaction refers to the process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid, often in an earthquake. [6]
The basic idea is to map zones that are susceptible to the process and then go in for a closer look. The presence or absence of soil liquefaction features, such as clastic dikes, is strong evidence of past earthquake activity, or lack thereof. These are to be contrasted with mud volcanoes, which occur in areas of geyser or subsurface gas venting.