爆炸挤淤作用对海相软黏土压缩特性的影响

浙江漩门三期围垦项目中采用爆炸挤淤置换法进行筑堤工程，为了对爆炸置换后海堤的固结沉降预测及稳定性评价提供可靠的试验参数，取爆炸前后地基范围内的海相软黏土，进行一维压缩和各向等压固结试验，并对该地区软土的压缩变形与结构特性进行初步研究。试验结果表明，海相软黏土存在一定的结构特性，表现出与其重塑土不同的性质；通过引入孔隙指数的概念，研究该地区软黏土的结构性，证实土体结构性的存在是其压缩特性不同于重塑样压缩曲线的内在原因，在高压力范围内其压缩曲线趋近于固有压缩曲线。爆炸挤淤作用对海相软黏土产生较强的扰动效应，也对其基本物理性质与压缩特性均产生重要影响；扰动效应造成软黏土的结构屈服应力降低，结构强度下降，采用新定义的结构破坏比来定量评估爆炸挤淤作用对海相软黏土结构性的破坏程度，可为爆炸挤淤置换法处理软基的海堤工程提供一定的理论基础。

Effect of squeezing silt by blasting on compression characteristics of marine soft clays

The blasting-based squeezing and replacing method has been used to treat the soft clay in constructing the rockfill embankments in the reclamation projection in Xuanmen area,Zhejiang province.To obtain reliable soil parameters for the settlement prediction and stability analysis of embankments,in situ soils were sampled just before and after blasting operation in the range of foundations.Then oedometer consolidation and equipressure consolidation tests were performed.The compression and structural characteristics are preliminarily studied on the marine soft clays in the area.The results show that marine soft clays possess intrinsic structure,and behave differently from its disturbed counterpart.With introducing the concept of void index,the effect of soil structure is investigated,showing that the structure of soft clays is the intrinsic reason that the compression characteristics is very different between marine soft clay and its remolding counterpart;and the compression curves of undistributed soils and distributed soils merge into a single curve in the high pressure range.Blasting-based squeezing method can make marine soft clayey soils disturbed largely.And it influences significantly the physical and compression properties of clayey soils.Furthermore,the structural yielding stress and the structural strength are both reduced undergoing the disturbance effect.The defined structural destructive ratio can be used to quantify the degree of damage from blasting-based squeezing effect on the structure of the marine clayey soils.These results may be significant for developing the theoretical basis of blasting-based squeezing for treating the soft foundation of embankments.