冻土材料宏-微观结构性模型研究

Study on macro-micro structural model of frozen soil

冻土是高原交通工程不可回避的问题,冻土研究不仅涉及土体结构,还涉及温度和含水量对土体的影响,目前,冻土问题理论研究进展比较缓慢,是岩土领域研究的热点和难点.根据材料集合状态理论的思想和方法,建立了冻土材料的宏-微观模型.在宏观上建立了以冻土材料结构强度、刚度、塑性应变及孔隙比、饱和度、温度为参量的冻土材料结构状态集合函数的控制方程;在微观上建立了以土颗粒、冰、水为结构要素而形成的微结构元集合.通过以冻土材料的强度、刚度和结构应变为宏观约束条件,找到所有可能的微结构状态及其分布,以此为基础,建立冻土材料宏观参量与材料微观特征参数之间的关系.在一定的简化条件下,得到了冻土材料的状态集合函数的解析表达式,并由此形成冻土材料的强度准则、流动法则和应力-应变关系.

In the field of highland transportation,frozen soil is an inevitable problem needed to be solved.Frozen soil research not only focus on the structure of soil,but also the influences of temperature and water content on soil.As the hot spot and difficulty of the geotechnical field,frozen soil’s theoretical research is relatively slow in progress.Based on the idea and method of material set state theory,a macro-micro model of frozen soil is established.The control equations of the set function of the structure state of the frozen soil materials are established on the macroscopic basis of the structure strength,stiffness,plastic strain,void ratio,saturation and temperature.On the microscopic level,we set up a set of micro-structural elements that are formed by soil particles,ice and water.By taking the strength,stiffness and structural strain of frozen soil as macro constraints,all possible micro-structural states and their distribution are found.In this connection,the relationship between the macroscopic parameters and the microscopic characteristic parameters of the frozen soil materials is established.Under certain simplified conditions,the ana-lytic expression of state set function of frozen soil is obtained,forming the strength criterion,flow rule and stress-strain relationship of frozen soil.