Study on Field Immersion Test of Large Thickness Self-weight Collapsible Loess Sites

To solve the problems of collapsibility evaluation and foundation treatment in construction of large thickness self-weight collapsible loess sites, field immersion test was conducted. The rule of water injection rate, the movement of moisture field, the collapse characteristics of surface and underground, the development characteristics of cracks around the test pit, the influence range of both immersion and saturation, the permeability coefficient of foundation soil, the lower limit depth of self-weight collapsible loess and criteria were studied. On this basis, a method is proposed to calculate the correction coefficient β₀ which varies with the soil quality in different areas by considering the sedimentary age of the strata. A preliminary discussion on criteria of self-weight collapse of loess has been conducted. The result is: 0.015 is appropriate for Q₃ loess but not for Q₂. It is suggested that field immersion test should be conducted to evaluate self-weight collapse of Q₂ loess. The research results can provide reference for regional engineering construction.