袋装砂围堤施工变形控制标准

海堤工程通常坐落于淤泥软土地基上,面临潮汐、恶劣天气等复杂的环境条件,确定海堤工程的变形控制标准是一个难题。基于某圈围工程袋装砂围堤的实测资料,从沉降速率、水平位移速率、堤中沉降速率与坡脚水平位移速率的比值3个指标对海堤工程的变形控制标准进行研究。结果表明,围堤堆载期间边界效应明显,将沉降速率作为袋装砂围堤稳定性的主要判据有一定的局限性,建议随着加载过程和位置的差异变化调整沉降速率控制标准;受挤淤效应的影响,浅表层的水平位移速率有可能大幅超越规范值,不宜用于控制围堤初期施工。分析基于堤中沉降速率与坡脚水平位移速率的比值提出的临界状态线指标对袋装砂围堤进行变形控制的有效性,并提出相应建议。

Deformation control standard for construction of large sandbag embankment

The sea dikes is often constructed on silty soft ground and faces complicated environmental conditions such as tidal current and bad weather,and it is difficult to determine the deformation control standard of the sea dike project.Based on the measured data of the large sandbag embankment in Hengsha Island,we study the deformation control standard of the embankment from three indices,i.e.,the settlement rate,horizontal displacement rate,and ratio of settlement rate in the channel to horizontal displacement rate at the slope foot.The results show that the boundary effect is obvious during the surcharge period of the embankment,and it is limited to take the settlement rate as the main criterion of the stability of the large sandbag embankment.Since the horizontal displacement rate at the shallow strata is possibly beyond the standard value due to the compaction effect,it shall not be used to control the initial construction of embankment.The validity of the critical state line based on the ratio of the settlement rate in the channel to the horizontal displacement rate at the slope foot to control the stability of the large sandbag embankment is verified,and corresponding suggestions are put forward.