湿陷性黄土地基DDC桩合理桩间距优化设计

为研究湿陷性黄土地区DDC法（孔内深层强夯法）进行地基处理时合理桩间距的控制问题，在代表性场地采用不同桩间距处理地基，对其处理前后地基土的干密度和湿陷系数等指标做了比对，并分析其挤密效果，得出当桩间距为预成孔直径d的3倍时，地基土受到挤密所产生的侧向力是相对均匀的，当桩间距〉3．0d时，三桩间土体的挤密效果明显较两桩间差，故挤密法处理湿陷性黄土地基时的有效挤密区为3．0d，即DDC处理地基时的合理桩间距为3．0d．

The Optimal Design of the Reasonable Pile Spacing between DDC Piles of Collapsible Loess Foundation

This paper researches the control of the reasonable pile spacing in collapsible loess areas when the DDC （Deep-in-Hole Dynamic Compaction） method was used to treat the foundation. We treated the foundation by using different pile spacing in representative sites, compared the dry density and coefficient of collapsibility of foundation soil untreated and those of soil treated, and analyzed the compaction effect of the soil. The results show that the lateral force of the soil produced by compaction is relatively uniform when the pile spacing is three times the diameter of the prefabricated hole~the compaction effect of the two pile spacing is obviously not as good as that of the pile spacing when the pile spacing was more than three times the diameter. Therefore, the effective zone, or the reasonable pile spacing is three times the diameter of the prefabricated hole when the DDC method is used to treat the foundation in collapsible loess areas.