改进的分层总和法在黄土地区高填方地基沉降变形中的应用研究

Research on application of improved layered summation method insettlement and deformation of high fill foundation in loess area

黄土高填方沉降变形控制是工程建设的重点和难点。通过室内侧限压缩试验和加湿试验,总结了重塑黄土在自重应力和含水率变化下的变形特征。基于分层总和法的思想,引入了Gunary模型和割线模量法,将黄土高填方地基的沉降分为荷载引起的施工沉降和含水率变化引起的施工后沉降,并提出了黄土高填方地基沉降变形的计算方法。结合实际工程背景,预测了高填方工程的沉降变形。结果表明:黄土高填方沉降的主要来源是施工期荷载引起的沉降;随着填土高度的增加,工后沉降占总沉降的比例逐渐增大;在最优含水率条件下,当施工期压实度达到95%以上时即可完成土的排气固结,施工后期为土的排水固结;压实度的控制对高填方工程至关重要;该研究成果丰富了黄土高填方地基沉降变形的计算理论,为黄土高填方工后沉降和湿陷性沉降的研究提供了理论依据,并对黄土高填方工程的施工及工后沉降控制具有一定的参考价值。

The settlement deformation control of loess high fill is the key and difficult point of engineering construction.The deformation characteristics of remolded loess under the variation of self-weight stress and moisture content were summarized through laboratory confined compression test and humidification test.Based on the idea of layered summation method,the Gunary model and secant modulus method were introduced,the settlement of loess high fill foundation was divided into construction settlement caused by load and postconstruction settlement caused by water content change,and the calculation method of settlement deformation of loess high fill foundation was put forward.Combined with the practical engineering background,the settlement deformation of high fill engineering was predicted.The results show that the main source of loess high fill settlement is the settlement caused by construction load.With the increase of fill height,the proportion of postconstruction settlement to total settlement increases gradually.Under the optimum water content,when the compactness is over 95%during the construction period,the exhaust consolidation of soil can be completed,and the drainage consolidation of soil can be completed in the later construction period.The control of compaction degree is very important for high fill engineering.The research results enrich the calculation theory of settlement deformation of loess high fill foundation,and provide theoretical basis for the study of post-construction settlement and collapsible settlement of loess high fill foundation.It is of certain reference value to the construction and postconstruction settlement control of loess high fill project.