Controlling differential settlement between new and old foundations, shortening the construction periods are the key for embankment widening projects.In order to reflect the reinforcing mechanism and effect of composite ground of pre-stressed pipe piles applied for highway embankment widening,the deformation characteristics of the composite ground was investigated by field test-dynamic monitoring of settlement,differential settlement,deep settlement,and lateral movement.The results showed that;(1)The composite ground reduced 80% of the natural settlement, and effectively controlled the differential settlement between new and old embankments, to meet the design requirements.(2) Settlement and lateral movement of the composite ground were very small, and converged quickly,and thus could meet the requirement of short construction periods.(3) Settlement and lateral movement mainly occurred in the range of consolidating depth,and the values were much lower than the control standard.%控制新老路基差异沉降、缩短建设周期是高速公路拓宽工程的技术关键.为反映PHC管桩加固高速公路拓宽软基的作用机理及应用效果,针对管桩复合地基的变形性状进行现场试验,分别从地表沉降、差异沉降、深层沉降、侧向位移等4个方面实施为期9个月的动态监测与分析,得到拓宽荷载作用下管桩复合地基沉降和侧向位移的变化规律,以及管桩复合地基的加固效果.结果表明:(1)复合地基使拓宽路基沉降减少80%以上,并有效控制新老路基差异沉降,达到了设计的预期目的;(2)PHC桩复合地基具有变形收敛快,工后沉降量小的特点,满足拓宽工程施工快、工期短的要求;(3)沉降和侧向变形主要发生在管桩加固深度范围内,实测变形量均远小于控制标准,设计方案存在一定的优化空间.
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