钢渣型复合基材在浅层软土固化中的应用

Application of Steel Slag Composite in In-situ Solidification of Shallow Soft Soil

浅层就地固化是软土地基处理的一项重要方向,近年来在工程建设中得到较为广泛的应用。传统就地固化主要以水泥为主,为了验证基于工业废料钢渣的复合系基材对不同软土地区浅层固化的效果,通过改变钢渣、偏高岭土、生石灰等成分的配比,在室内以无侧限抗压强度为指标,探讨不同成分配比的基材对不同地区软土固化强度随含水率、复合基材掺量和龄期变化的影响;此外,将室内试验最优配比应用于现场试验,在现场通过取芯测强度以及轻便动探评价承载力来验证复合基材对于浅层软土就地固化的效果,并对室内和现场所造成的强度差异进行了对比分析。研究结果表明:①基于钢渣的复合系基材能有效提高软土强度:②固化后强度与基材掺量、龄期成正相关关系,与含水率成负相关;③在浙江湖州现场就地固化中,复合基材掺量大于3%,改性水泥与钢渣掺量比为1.2∶1.8时,可满足固化土强度和地基浅层承载力的要求;④现场搅拌均匀性是影响室内与现场强度差异的主要原因。

The in-situ shallow solidification of soft soil is an important issue of ground improvement,which has been widely used in engineering construction in recent years. For in-situ solidification,cement is the main agent. To recycle industrial wastes and control the project costs,the steel-slag,a kind of byproducts,was modified by cement,quick lime and metakaolin to form a new composite aiming to solidify the soft clay. The relationship between the unconfined compression strength of the improved soils and their water contents,binder component and contents,and curing periods was discussed. Furthermore,the optimal proportion was adopted in the field. In the field application,the strength of in-situ samples and dynamic cone penetration were used to evaluate the quality,the intensity difference between lab and in-situ experiments is compared and analyzed. The results show that:(1)The steel slag-based composite can effectively improve the strength of soft soil;(2)The strength was positively related with binder content and curing periods,whilst negatively related with water content;(3)In this case,when composite content is more than 3% and the ratio of MK-cement to steel slag is 1.2∶1.8,the strength of solidified soils and bearing capability can both meet the design requirements;(4) The mixing uniformity is the main reason for the difference between lab and in-situ strength.