高黏粒含量新吹填淤泥加固新技术室内研发

Laboratory tests on new reinforcement technology of newly hydraulic reclamation mud with high clay content

新吹填淤泥处于"稀泥汤"状态,工程特性极差,几乎无承载力,现有真空预压技术加固效果不理想,地基有效加固深度小,土体强度增长有限。为此,提出了"真空预压联合化学加固"的新思路。室内采用3种环保型化学加固剂设计了3种真空预压联合化学加固方案(VPCT1、VPCT2、VPCT3)和1种纯化学加固方案(CT),与现行真空预压加固方案(VPT)进行了对比试验研究。研究结果表明:(1)添加有效的化学加固剂后,新吹填淤泥在抽真空前较短的静置时间内就基本完成了自重沉积过程;(2)化学加固剂选取得当能有效提高土体的加固效果;(3)宏观上,VPCT3方案加固效果较均匀,加固后土体中黏粒含量明显降低、湿密度最大,孔隙比降低幅度明显,无侧限抗压强度也最大,为66.7 k Pa(为VPT方案的3.5倍);(4)微观上,VPCT3方案加固后,土颗粒之间的孔隙总面积、孔隙平均周长、总孔隙数、孔隙比、孔隙率等最小,单元体之间有良好的定向度、排序性最好,连结方式以面-面为主导,相互之间接触紧密,团聚现象最明显。因此,相对于现行的真空预压技术而言,VPCT3方案土体加固效果非常明显,也较均匀,可以进一步开展现场试验研究,探讨其付诸于工程实践的可行性。

The engineering properties of newly hydraulic reclamation mud in liquid state are poor. Their bearing capacity is almost zero. After it is improved with vacuum preloading technology（VPT）, its soil strength increases only a little and its effective depth is very small. A new idea of vacuum preloading combined with nonpolluting chemical reinforcement technology（VPCT） is proposed. Three kinds of vacuum preloading combined with chemical reinforcement technologies（VPCT1, VPCT2 ＆VPCT3） and one kind of chemical improvement technology（CT） are compared with VPT in laboratory tests. The test results show that：（1） when the effective chemical agent adding, the deposition of newly hydraulic reclamation mud finishes after a short standing time before vacuum preloading;（2） the effective chemical agent can promote the improvement effect;（3） in macrocosmic aspects, the mud of VPCT3 has uniform improvement, the clay content obviously decreases, the wet density is the biggest, the void ratio obviously decreases, and the unconfined compression strength is the biggest（66.7 k Pa） which is 3.5 times that of VPT;（4） in microcosmic aspects, the mud of VPCT3 has the smallest total region（void） area, average perimeter, region（void） number, void ratio, porosity, and has good directionality, intimate contact with mainly surface-to-surface connection, and has most noticeable agglomerate phenomenon. Therefore, comparing with VPT, VPCT3 has the best effect for improving the mud. It is advisable ＆ necessary that VPCT3 is further researched in field trial.