Public Works Department, Taipei City Government

Soil liquefaction refers to phenomena that when soil is under violent shaking, the water pressure (pore-water pressure) among soil particles increases, causing the contact force (effective stress) among particles to be reduced. When such contact force diminishes, soil particles are suspended in the water and lose their carrying capacity. Consequently, the entire solid soil becomes liquid mortar. When the pore-water pressure is too high, the water and parts of the sandy soil can erupt out of the ground from the cracks in the stratum, leading to the phenomena of sand eruption. Accordingly, the primary environmental criterion causing soil liquefaction are: (1) loose sandy soil and low plasticity silt or clay, (2) high ground water level (high water content) and (3) sufficiently large vibration force (violent shaking).