排水板和砂井联合堆载预压加固海相软土地基的工作性状的现场试验

Field test on behaviours of marine soft soil foundation treated with plastic drainage plate and sand column combined with surcharge preloading

针对场地内夹杂岸堤、塘埂和人行道路网的深厚海相软土地基处理,提出塑料排水板和袋装砂井联合堆载预压加固方法,并通过现场试验研究该类地基在路堤填筑及堆载预压过程中的地表及深层沉降特性、超孔隙水压力消散机制和地基水平位移规律等工作性状。结果表明,采用该方法处理深厚海相软土地基具有良好的加固效果,地基沉降大部分在填筑期和预压期间发生,有效降低了场地的工后沉降和施工工期,可为沿海深厚复杂海相软土地基加固处理提供参考;塑料排水板和袋装砂井联合堆载预压处理地基的沉降-时间曲线呈多级式发展,袋装砂井处理部位的沉降量小于塑料排水板处;软基上部土体的排水效果明显优于中、下部土体,排水板处理区域的超孔隙水压力大于砂井处理区域;软基顶部土体向堆载区域移动,地表3 m以下的软土层被挤向堆载处理区域外。

In order to solve the technical difficulties to reinforce the deep marine soft soil foundation that including walkway network, the reinforcing technology by plastic drainage plate and sand column combined with surcharge preloading is proposed to reinforce the large scale complex deep marine soft soil foundation. The mechanical behaviors of the reinforced soft soil foundation during embankment filling and preloading are studied including the surface settlement and deep settlement characteristics, the excess pore water pressure dissipation mechanism, and the horizontal displacement law by field tests. The results show that the construction method used to reinforce the deep marine soft soil foundation has achieved good reinforcing effects. The settlement of the deep marine soft soil foundation accomplished mostly during the period of filling and preloading, which effectively reduce the post-construction settlement and construction period. The results provide an important reference for the reinforcement of the complex deep marine soft soil foundation. The settlement versus time curve of the marine soft soil foundation treated with plastic drainage plate and sand column combined with surcharge preloading is multistage development model. The settlement at the site reinforced by sand column is less than that at the site reinforced by plastic drainage plate. Meanwhile, the excess pore water pressure at the site reinforced by plastic drainage plate is greater than that at the site treated with sand column. The drainage effect of the upper soft soil is significantly superior to the lower. The top soil of the soft foundation under surcharge preloading would move to the treated area; while the soft soil below the surface 3 m would be pushed outside the region treated with plastic drainage plate and sand column.