薄砂层长短板结合真空预压法处理吹填淤泥土试验研究

Experimental research on hydraulic filled mud consolidated by vacuum preloading method combining long and short boards with thin sand cushions

薄砂层长短板真空预压法是快速加固新近吹填淤泥的一种新工艺。研究表明,抽真空90～120 d吹填淤泥土层平均压缩量可达到30%,呈现明显的大变形特征;平均固结度可达到80%以上;强度增长明显,检测表层承载力可达到50 kPa以上。该方法节省用砂量,便于泥面插板施工,显著改善表层排水条件,能满足浅层快速加固的建设要求。设置护膜土工布有利于水平排水和膜下真空度稳定。设置薄砂层和长短板结合的竖向排水体形式,可平衡和抑制负压作用下新近吹填淤泥土颗粒的径向流动,避免出现排水板周围淤泥抱团而导致的径向排水通道堵塞问题,保障场地加固效果的均匀性。加固后吹填淤泥的物理力学性质得到大幅度改善,与正常淤泥质软土相比,其发展趋势和轨迹是相符的,主要指标值之间的相关性规律是基本一致的。

The vacuum preloading method combining long and short boards with thin sand cushions is a new technology to consolidate newly reclaimed mud foundation.The experimental research indicates that the average soil compression reaches 30%,obviously showing large deformation features,and the average degree of consolidation reaches above 80% after vacuum preloading of 90~120 days.The soil strength significantly increases and the surface bearing capacity reaches 50 kPa or above.This method needs less amount of sand and is convenient for inserting the plate on the surface and improves the surface drainage condition significantly.To this end it can meet the requirements of the construction of shallow rapid reinforcement.The geotextile to protect the membrane can maintain steady vacuum degree under the membrane and benefit drainage consolidation and strength increase.By placing the sand cushions and vertical drainages with long and short boards,the radical flow of soil particles in the newly reclaimed mud foundation with extra high water content under negative pressure can be balanced and controlled,the radical drainage channel congestion in duled by mud gathering around the drainage boards can be avoided,and the uniformity of the consolidation effect is thus ensured.The physical and mechanical properties of the reclaimed mud foundation is significantly improved after consolidation,whose developing trend and orbit are in agreement compared with those of the normal mud soft soil,and the correlation laws of their main indices are consistent in general.