城市堤路结合工程变形控制措施研究

Study on deformation control measures of urban levee road combination

有效控制变形是城市堤路结合工程正常发挥防洪和交通双重作用的重要保障。基于南京长江岸线堤路结合工程典型断面,建立平面应变有限元数值模型,分析天然堆载、台阶加筋、深层水泥搅拌(DCM)及透水混凝土桩(PCP)工况等4种工况的变形分布与发展规律。研究结果表明:台阶加筋工况的整体变形规律与天然堆载工况基本一致,不进行软基处理将无法有效缩减新老堤防及地基的沉降和水平位移;DCM及PCP工况均能有效控制上部堤防及下部地基的沉降、隆起与水平位移,工后沉降均小于100 mm;PCP复合地基可在3.6%的低置换率条件下,将路面工后沉降减至43 mm,并将达到99%固结度的时间由365 d缩至155 d,变形控制能力整体强于DCM工况。PCP复合地基技术在变形控制标准高、建设周期短的软基地区堤路结合工程中具备良好的应用前景。

Effective control of deformation is an important guarantee for the urban levee road combination works to play the dual role of flood control and transportation.Based on the typical section of the levee road combination project along the Yangtze River in Nanjing,a plane strain finite element numerical model is established,and the deformation distribution and development laws of four conditions,namely,natural surcharge,step-reinforcement,deep cement mixing(DCM)and pervious concrete pile(PCP),are analyzed in depth.The research results show that the overall deformation law of the step-reinforcement condition is basically consistent with the natural surcharge condition,and the settlement and horizontal displacement of the new and old levees and foundation can not be effectively reduced without soft foundation treatment.Both DCM and PCP conditions can effectively control the settlement,uplift and horizontal displacement of the upper embankment and the lower foundation,and the post construction settlement is less than 100 mm.The PCP composite foundation can reduce the post construction settlement of the pavement to 43 mm under the condition of low replacement rate of 3.6%,and shorten the time to reach 99%consolidation degree from 1 year to 155 d,and the deformation control ability of PCP condition is better than that under DCM condition.PCP composite foundation technology has a good application prospect in levee road combination project in soft foundation area with a high deformation control standard and a short construction period.