超细颗粒悬浮状疏浚土真空预压加固特性研究

浙江省乐清湾地区疏浚土具有高孔隙比、高黏粒含量、高含水率、高触变性、抗剪强度低及排水缓慢的特性，工程性质差，加固困难。依托乐清湾北港区吹填区真空预压工程，设置4个3 000 m2的真空预压试验区，研究相同真空度下不同塑料排水板间距、型号加固效果的差异，通过膜下真空度、表层沉降、孔隙水压力等监测数据以及土体含水率、十字板抗剪强度的检测结果对加固效果进行分析，同时结合含水率、十字板抗剪强度等检测数据，对无结构疏浚土的物理力学指标离散性进行分析。结果表明，采用真空预压加固超细颗粒无结构疏浚土时，对于浅层加固，A与B型排水板没有明显差别，塑料排水板间距小于100 cm时加固效果提升不明显；无结构疏浚土加固后力学指标较离散而含水率指标较稳定，建议采用含水率作为验收指标；建议无结构疏浚土采用土的三相组成推算其压缩比和沉降量。

Characteristics of vacuum preloading reinforcement of ultrafine particle suspended dredgedsoil

Dredged soil in the Leqing Bay area of Zhejiang Province has the characteristics of high pore ratio,high clay content,high moisture content,high thixotropy,low shear strength,and slow drainage.Its engineering properties are poor,and reinforcement is difficult.Combining with a vacuum preloading project in the north port area of Leqing Bay reclamation area,we set up four 3 000 m2 vacuum preloading test areas to study the differences in reinforcement effects of different plastic drainage plate spacing and models under the same vacuum degree,and analyze the reinforcement effect through monitoring data such as membrane vacuum degree,surface settlement,pore water pressure,as well as detection results of soil moisture content and vane shear strength.Then we analyze the dispersion of physical and mechanical indicators of unstructured dredged soil based on a large amount of testing data on moisture content and vane shear strength in the test area,and provide suggestions for reasonable acceptance indicators after reinforcement.The results show that when using vacuum preloading to reinforce ultrafine particle unstructured dredged soil,there is no significant difference between A-type and B-type plates for shallow reinforcement,and the improvement of reinforcement effect is not significant when the spacing between plastic drainage plates is less than 100 cm.After the reinforcement of unstructured dredged soil,the mechanical indicators are relatively discrete while the moisture content indicator is relatively stable.It is recommended to use the moisture content as the acceptance indicator.It is recommended to use the three-phase composition of the soil to calculate the compression ratio and settlement of unstructured dredged soil.