安康机场罗家河膨胀土高填方沉降变形特征研究

Settlement and deformation characteristics of high fill of Luojiahe expansive soil in Ankang Airport

安康机场罗家河高填方是国内罕见的膨胀土填方体。通过表面与底部涵洞沉降监测,对其沉降变形特征进行了研究。结果表明,膨胀土高填方次固结阶段的表面沉降受降水影响显著,出现反复膨胀变形,最大膨胀速率为0.485mm/d;建立了考虑填方厚度与沉降时间的膨胀土高填方工后沉降预测模型,模型参数u可表征挖填交界面处地基沉降在此处产生的拖拽效应引起的沉降量,模型计算值与实测值平均相对误差为12.17%,该模型可为地质条件与填筑材料类似工程的工后沉降预测所借鉴;依据填方体胀缩变形可将其分为8个阶段,胀缩变形阶段均与时段降水量关系密切,其中缓升段Ⅶ时段降水量为644mm,对应的膨胀量达44mm;该膨胀土填方体总体表现为膨胀,而非其他岩土填筑体的压缩变形。

The Luojiahe high fill of Ankang Airport is a rare expansive soil fill in China.In this study,the settlement characteristics of fill are studied by monitoring the settlements of surface and bottom culverts.The results show that the surface settlements of expansive soil at the secondary consolidation stage of high fill are significantly affected by precipitation,and the repeated expansive deformation occurs with the maximum expansion rate of 0.485 mm/d.The prediction model for the post-construction settlement of high fill of expansive soil is established incorporating the fill thickness and settlement duration.The model parameter u can represent the settlement caused by the drag effects caused by the foundation settlement at the interface of the cut and the fill.The average relative error of the value is 12.17%.This model can be used as a reference for predicting the post-construction settlement of projects with similar geological conditions and filling materials.The expansive and compressive deformations of the fill can be divided into 8 stages.The monitored deformation stages are closely related to the precipitation in the period.The rainfall at the slowly rising stage VII is 644 mm,and the corresponding expansive deformation is 44 mm.The expansive soil fill generally shows expansion rather than compression of other geotechnical fills.