（1 太原理工大学建筑与土木工程学院， 太原 030024； 2 北京市勘察设计研究院有限公司，北京  100038； 3 陕西龙海工程建设有限公司， 西安 710003）

［摘要］由传统技术改进而来的内外套管组合沉管夯扩法，是一种利用内外套管组合沉管成孔，加大成孔深度，再由重锤二次夯扩挤密的新技术，地基处理深度可达60m。结合具体的工程，对在大厚度湿陷性黄土地基中使用该方法成桩的桩长26，32，35m的灰土挤密桩和桩长20，32，36m的水泥土挤密桩进行现场试验研究，测得两种桩间土挤密系数均不小于0-93，桩体压实系数均不小于0-97，湿陷系数均小于0-015，满足规范要求；同时承载力也满足设计要求。

［关键词］大厚度湿陷性黄土； 内外套管组合沉管夯扩法； 地基处理

中图分类号：TU444文献标识码：A文章编号：1002-848X(2019)06-0134-04

Field test study on sinking ramming by combination of internal and external casing method in  thick collapsible loess foundation

Wang Ding1, Ge Xinsheng1, Zhen Zheng1, Li Bin2， Liu Qingjie3

(1 School of Architecture and Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, China; 2 Beijing Geotechnical Institute Co., Ltd.,  Beijing 100038, China;  3 Shaanxi Longhai Engineering Construction Co., Ltd., Xi′an 710003, China)

Abstract:The sinking ramming by combination of internal and external casing method is obtained  by  improving traditional technology. It is a new technology that makes use of combination of internal and external casing to sink and form holes, enlarges the depth of hole formation, and then uses heavy hammer to compact by twice sinking and ramming. The depth of foundation treatment can reach 60m. Combining with specific projects, field test study of lime-soil compaction pile length of 26, 32 and 35m and cement-soil compaction pile length of 20, 32 and 36m which formed by the above-mentioned method were carried out on thick collapsible loess foundation. The results show that the compaction coefficient of soil between piles is not less than 0-93, the compaction coefficient of pile body is not less than 0-97, the collapsibility coefficient is less than 0-015, which meets the requirements of specifications, and the bearing capacity also meets the design requirements. 

Keywords:thick collapsible loess; sinking ramming by combination of internal and external casing method; foundation treatment

作者简介：王鼎，硕士，Email:476565534@qq.com。