该文以西安地区某工程为例，通过地层结构和主要物理力学指标、SDDC工法挤密桩施工质量、CGF桩桩周土取样试验、现场地层取样对比等研究，分析湿陷性黄土场地SDDC法预处理质量不佳时，对工程带来的不利影响。研究表明，湿陷性黄土场地采用SDDC工法，含水率超过20%时，湿陷性较难消除，且桩身填料挤密系数和桩中心挤密系数均难满足设计要求。在湿陷性黄土场地，SDDC工法挤密桩处理效果对含水率敏感，含水率是控制性因素，不宜处理含水率较高的地基土层。当SDDC挤密桩桩身挤密系数达不到设计要求时，桩间土和桩中心挤密系数也达不到设计要求。本研究成果可为类似工程建设提供经验参考。

The paper takes a project in Xi′an as a case study to analyze the adverse effects on the project caused by inadequate pretreatment quality of SDDC(Super-Dense Dynamic Compaction) in a collapsible loess site through the studies of stratigraphic structure, main physico and mechanical parameters, construction quality of compaction piles by SDDC method, soil sampling tests around CGF piles, and comparative on-site stratum sampling. The results show that the collapsibility is difficult to be eliminated and both the compaction coefficient of pile fill material and pile centers fail to meet design requirements when SDDC method is used in a collapsible loess site with the moisture content exceeds 20%. In a collapsible loess site, the treatment effect of SDDC compaction pile is sensitive to water content, which acts as a controlling factor, therefore, it is unsuitable for foundation soil layers with high moisture content. When the compaction coefficient of compaction piles by SDDC method can not meet the design requirements, the compaction coefficients of the inter-piles soil and the piles centers will also fall short of design requirements. The results of this study can provide practical reference for similar engineering projects.