高速公路扩建工程软基拓宽的沉降监测与分析

高速公路拓宽建设中新老路基特别是软土路基的固结沉降与力学性质的差异将引起严重的路面开裂，因而控制其差异沉降、防止拼接处路面开裂成为扩建工程软基处理中的技术关键。针对采用薄壁管桩和粉喷桩处理的软基路段，选取具有典型地质条件及较高填方的断面，通过埋设地面沉降板，对拓宽路基及新老路堤结合部进行了为期9个月的沉降动态监测。监测结果表明，拓宽路基的累计沉降及差异沉降均很小，后期沉降速率小于控制标准，为新老路基差异沉降的评价提供了依据；薄壁管桩用于处理埋深大、层厚大的拓宽软基及粉喷桩用于处理埋深浅、层厚较小的拓宽软基具有各自的适用性，拓宽后的新老路基已形成整体性强的复合地基，达到了路基拓宽的理想效果。

Settlement monitoring and analysis for soft foundation of an expressway widening project

In expressway widening construction,differential consolidation settlement and mechanical properties between new and old foundations especially soft foundation will cause severe pavement crack;and controlling differential settlement to avoid pavement crack in joint section becomes the key technique in embankment widening project.Focusing on soft foundation treated respectively with thin-wall pipe piles and DJM piles,selecting sections with typical geotechnical condition and comparatively high embankment,by burying settlement plate,a dynamic monitoring has been performed for obtaining the settlement of foundation during embankment widening.The results indicate that(a)the accumulated and differential settlement are both small and the settlement rate is smaller than the controlling standard,which provides basis for differential settlement accessing and(b)the two disposal methods,thin-wall pipe piles and DJM piles,are respectively accommodated for soft foundation with large embedded depth and layer thickness and with small embedded depth and layer thickness;and the treated new and old foundations is turned into fine compound foundation;so,a satisfied result is obtained for foundation widening.