公路膨胀土路堤膨胀变形预测方法

Prediction Method for Expansion Deformation of Highway Expansive Soil Embankment

为保证运营期包边膨胀土路基的长期稳定,对膨胀土路堤填筑后产生的膨胀变形进行预估。利用非饱和土的湿热耦合理论,构建了膨胀土路堤湿度变化的计算方法;根据膨胀土的侧限膨胀试验,推导出了考虑现在应力状态和将来应力状态的膨胀变形的预估模型;依托实际工程研究了大气作用下公路膨胀土路基湿度的变化规律,对膨胀土填料的平衡含水率和膨胀变形进行了计算。结果表明:膨胀土路基的平衡含水率仅与当地的气候条件以及地下水位有关,与初始压实控制含水率无关;在初始干密度不变的情况下,膨胀土的膨胀系数随初始含水率的增大而增大;填筑膨胀土路基时,应尽量采用路基平衡含水率作为路基的填筑控制含水率。研究成果可为膨胀土路堤填筑技术提供理论参考。

In order to ensure the long-term stability of the expansive soil subgrade,the expansion deformation of the expansive soil embankment after filling is estimated.Firstly,based on the damp-heat coupling theory of unsaturated soil,the calculation method of moisture change of expansive soil embankment is constructed.Secondly,based on the lateral expansion test of expansive soil,the prediction model of expansion deformation considering the present stress state and the future stress state is derived.Finally,based on the actual project,the moisture balance law of highway expansive soil subgrade under the action of atmosphere is studied,and the equilibrium moisture content and expansion deformation of expansive soil filler are calculated.The results show that the equilibrium moisture content of expansive soil subgrade is only related to local climatic conditions and groundwater level,and is not related to the initial compaction control moisture content.When the initial dry density is constant,the expansion coefficient of expansive soil increases with the increase of initial moisture content.When filling expansive soil subgrade,the equilibrium moisture content of subgrade should be used as the filling control moisture content of subgrade as far as possible.The research results can provide theoretical reference for the filling technology of expansive soil embankment.