【摘要】 为研究长江三角洲区域性软土路基的沉降特点,对长三角地区滨海相软土的沉积环境、地层分布特点和工程特性进行了系统分析。基于研究区内典型软土地段高速公路软基沉降的观测数据,研究了该地区软基沉降的变化规律,分析了场地工程地质条件和填土高度等因素对软土路基沉降的影响。结果表明:长三角地区海相软土地层与陆相地层相互交叠,海相软土具有高压缩性、低强度和较强的结构性;软基沉降曲线有3种类型,沉降量随硬壳层厚度减小、软土层厚度增加而增加,不同软土路基处理路段的沉降特点具有显著差异。更多还原

【Abstract】 The article is aimed at bringing about its investigation and systematic analysis results of the particular settlement features of the soft soil subgrade in Yangtze River delta,the sedimentary environment,the stratigraphic distribution characteristics, and the engineering operation particularities of the marine soft soils in the area. We have also carefully analyzed and examined the variation regularities of the settlement curve on the basis of tracing the settlement data base of the soft soil subgrade in terms of typical highway construction in this area. What is more,we have also analyzed the effects of engineering geological conditions and height of filling on the settlement of the said soil subgrade. Theresults of our investigation and analysis indicate that the marine soft soil layer and the continental strata tend to overlap each other. The area under study is a marine soft soil layer over 10 m thick as a result of long-years’ silt-up,or deposition on the surface of the original soil base. It enjoys high compressibility,low strength and strong structural features. The particles of the soft clay are mainly composed of clay and silt,with the changes of moisture content being from 30% to 50% and the value of plastic limit being approximately 20%. In addition,the marine clay is also characteristic with a strong structure whereas the permeable channels result in among the pores,which make it difficult to compress before the overburdened stress goes up to the yield stress. And,in terms of geographical features,the soft soil subgrade can be divided into three types of settlement curve,that is,the deep treatment section,that is,type one,and,those of nondeep treatment section can be seen as type two or type three. The critical filling heights of the subgrade with the non-deep treatment and deep treatment are about 2. 0 m and 3. 0 m,respectively. We have also found that the settlement tends to increase with the decrease of the thickness of hard crust and increase of the thickness of the soft soil layer. Such settlement characteristics of the soft soil subgrade treated with different methods can be found quite different from each other. Therefore,it is the hyperbolic method that would be suitable to be used effectively to predict such settlement features of the marine soft soil subgrade.更多还原