白水河大桥场区黄土地基湿陷性分析

Collapsibility Analysis on Loess Foundation in Baishuihe Bridge Area

摘要:

以白水河大桥施工场地黄土地层为研究对象，分析场地黄土的湿陷系数、自重失陷系数与深度的关系，湿陷量、自重湿陷量与深度的关系，研究得出场区的黄土湿陷特点：研究区地貌单元属河谷阶地区，地处阶地前缘斜坡处，发生湿陷的地层为上更新统风积黄土、古土壤及中更新统风积黄土层。湿陷性黄土主要有轻矿物、重矿物和粘土矿物组成。黄土的化学组成主要为SiO2，其次为Al2O3，Fe2O3和CaO等，但黄土湿陷性的发生与黄土的矿物组成及化学组成关系较小。综合分析研究区黄土湿陷性影响因素，认为湿陷性主要影响因素为含水状态，应力状态等。对比分析湿陷系数，湿陷量随深度的变化规律：随着计算深度的增加，湿陷量、湿陷系数均呈先增加后减少趋势。最终判定研究区地基湿陷等级为Ⅲ级，为严重湿陷。该研究成果对工程建设中遇到的黄土湿陷的分析及其治理具有重要意义。

Abstract:

Based on the loess strata in Baishuihe bridge area, the relationship between the coefficient of collapsibility and the coefficient of self-weight collapsibility, the relationship between content of self- weight collapsibility and the content of collapsibility have been analyzed. It is concluded that the landform of the study area is the valley terrace. It is located at the leading edge of the terrace. Wet subsident layers are early Pleistocene eolian loess, ancient soil and middle Pleistocene eolian loess. The Collapsible loess are formed by light minerals, heavy minerals and clay minerals. Chemical compositions of loess are SiO2, Al2O3, Fe2O3 and CaO. However, collapsibility loess has nothing to do with the mineral composition and chemical composition of loess. Through analyzing collapsibility of loess factors in study area, it is thought that main influcing factors are moisture state, stress state and so on. After analyzing the relationship between coefficient of collapsibility, it is regarded that the content of collapsibility and the depth of collapsibility will increase accompanying with the increase of depth, wet and collapsibility coefficient will increase first and then decrease. It is concluded that the wet sinking level of the foundation in study area is Ⅲ. It is serious wet subsidence. The research results have important significance for the analysis and treatment of the loess collapse in the construction.