基于接力排水的强夯法在滨海回填区地基处理中的试验研究

An experimental study of the dynamic compaction method based on relay drainage in foundation treatment of the coastal backfill area

本文对山东半岛海岸带滨海杂填土、饱和粉细砂、淤泥质土等特殊复杂地层地基处理方法进行了研究。以经济高效的强夯法为基础,提出复杂地层整体排水概念,设计了浅层、深层竖向排水和水平排水的接力排水系统,并进行了现场试验研究。监测数据表明,强夯荷载作用下,接力排水系统整体协同排水,可快速排出各个地层中地下水、消散超孔隙水压力。7 h左右可基本消除强夯引起的地下水上升及孔隙水压力消散。持续降水,地表沉降为上部土体厚度的0.7%~2.0%。强夯动力荷载作用下,表层土体压缩为上部土体厚度的8.7%~10.9%。埋深3~7 m土体沉降约为土体厚度的5‰、3‰,埋深7~10 m土体沉降为土体厚度的2‰。检测数据表明,在强夯有效影响深度内地基处理效果明显,土体工程性状改善明显。表层承载力及变形模量满足设计要求,4 m以下淤泥承载力平均值略低于设计要求,下部淤泥质土计算平均固结度为77%。夯后1个月监测数据表明,地表沉降量在25 mm以内,已逐步趋于稳定,分层沉降、孔隙水压力数值整体稳定略有下降。

The studies of foundation treatment methods are carried out for the special and complex foundation in the fill,saturated silty fine sand and silt in the coastal backfill area of the coastal zone of the Shandong Peninsula.Based on the economical and efficient dynamic compaction method,the concept of integrated combined drainage is put forward.The relay drainage system of the shallow and deep vertical drainage channels and their relay horizontal drainage channels are designed,and field tests are undertaken.The monitoring data show that under the dynamic compaction load,the relay drainage system can coordinate drainage as a whole,which can quickly discharge the groundwater to dissipate the excess pore water pressure.The rise of groundwater level and dissipation of pore water pressure caused by dynamic compaction can be basically eliminated in about 7 hours.With continuous precipitation,the surface settlement is 0.7%~2.0%of the thickness of the upper soil mass.Under the dynamic load of dynamic compaction,the surface soil is compressed to 8.7%~10.9%of the thickness of the upper soil.The soil settlement is about 5‰and 3‰of the soil thickness at the buried depth of 3~7 m,and 2‰of the soil thickness is at the buried depth of 7~10 m.The test data show that in the effective depth of dynamic compaction,the effect of foundation treatment is obvious,the engineering properties and the degree of consolidation of foundation are improved.The surface bearing capacity and deformation modulus meet the design requirements,the average bearing capacity of silt below 4 m is slightly lower than the design requirements,and the average degree of consolidation of mucky soil is 77%.The monitoring data of one month after tamping shows that the surface subsidence is within 25 mm,which tends to be stable,the layered settlement and pore water pressure are stable and slightly decreased.