Study of non-linear constitutional equation for humidifying collapse loess
Aijun Zhang · Journal of Northwest A&F University · 2011
【Objective】 The study was conducted to establish a constitutional equation for loess during humidifying collapse to provide theoretical foundation for numerical calculation of loess's humidifying collapse deformation.【Method】 Based on grading immersion traxial test on the condition of equal stress ratio,the paper applied three-parameter Sigmoid equation to fit the relation between average stress p and collapse volumetric strain eshv and the relation between deviator stress q and deviator strain eshr on the conditions of different water contents respectively,and then the three specific parameters of Sigmoid equations were gained.Later,the functional relation between those values of three parameters and water contents was built.Finally,the non-linear constitutional equation for humidifying collapse loess was acquired.Through this equation derivation and calculation,material parameters for humidifying collapse loess could be gained.【Result】 Using above-mentioned regression method,constitutional equations for the relation between average stress p and collapse volumetric strain eshv and the relation between deviator stress q and deviator strain eshr on the condition of different water contents were obtained respectively.Validity of those constitutional equations were proved by back calculation analytical method.【Conclusion】 This three-parameter Sigmoid equation is simple and easy to use which can express transformation behavior of collapsible loess commendably.