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Soil liquefaction is a dangerous phenomenon that occurs when saturated, sandy soil loses its stability in response to sudden stress, such as an earthquake. This causes the soil to behave as a viscous liquid, like quicksand. Soil liquefaction enhances the damage done by earthquakes and other natural disasters. Liquefied soil cannot support buildings, so structures tend to tilt, sink into the ground, or slide toward bodies of water. Other structures in the ground, such as pipelines and electrical cables, are disrupted, damaged, and may be thrust out of the ground. Landfills are likely to be compromised, and roads may crack or move laterally. In order to prevent or minimize this kind of damage, there are three soil liquefaction mitigation techniques which may be employed. Avoid vulnerable soils A qualified professional is required to decide if a specific site is susceptible to soil liquefaction. One way to decide whether the soil is vulnerable is to determine if liquefaction occurred there in the past. Another indicator of susceptible soil is the type of deposits that it is comprised of. Fluvial, alluvial, colluvial, and Aeolian deposits are vulnerable to liquefaction. Man-made soil deposits, such as those generated by hydraulic filling, may also be weak. Soil composition is another factor in the potential for liquefaction. Sandy soils and those with similarly-sized, round pieces are more likely to be compromised. Construct liquefaction-resistant structures Sometimes it is necessary to build on unstable soils, for example, because of a desired location or limited space. In these cases, flexible foundations may be built to combat the effects of liquefaction. If a shallow foundation is used, all the elements need to be connected, to allow the foundation to settle or move evenly. This reduces impacts to structures resting on the foundation. Pile foundations placed in weak soil must be able to withstand both vertical loads, from the structure, and horizontal force, from soil movement. Piles must be connected to the cap in a way that allows for some flexibility, to keep the structure from overturning during liquefaction. Buried utilities also need to have flexible connections, to the structure, to allow for movement during liquefaction. Upgrade the soil Soil liquefaction mitigation may also be achieved by improving the quality of the soil. This is accomplished by increasing the density, strength, or drainage traits of the soil, through a variety of techniques. Vibroflotation and Vibro Replacement employ a vibrating probe to make the soil denser. Dynamic compaction involves dropping a significant weight on unstable soil to make it firmer. The installment of stone columns strengthens the soil and allows for improved drainage. Compaction grouting is often used to improve the foundation of an existing structure. Drainage techniques, such as installing drains of sand, gravel, or synthetic materials, may be used in combination with other soil liquefaction mitigation solutions. When determining the soil liquefaction mitigation method to be used, it is necessary to balance the cost of the technique with the risk of liquefaction and potential damage. A variety of tests may be used to determine the effectiveness of the soil liquefaction mitigation technique used. However, sometimes the effects are not verifiable for some time after the improvement is implemented. The author has an immense knowledge on soil liquefaction mitigation. Know more about soil liquefaction mitigation related info in his website.
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