冲击式压路机治理湿陷性黄土地基的实践研究

Practice on treatment of collapsible loess foundation by impact roller

通过在宁夏银川至武汉高速公路桃山口至同心段高速公路非自重湿陷性黄土的施工中,采用了冲击式压路机法消除了黄土的湿陷性,提高了地基承载力,并取得了大量的试验数据.文章根据对施工后非自重湿陷性黄土地基的检测、评价和理论分析,总结了冲击式压路机法处理非自重湿陷性黄土地基需要控制的指标:①采用25 kJ冲击式压路机进行冲击施工时,冲击碾压遍数以40遍为宜,控制深度为0～90 cm,压实度应>90％;②平均沉降量应>25 cm,平均孔隙比应<0.55,0～200 cm黄土湿陷性基本消除.该试验结果已在同心至固原高速公路117 km,计2 227 211 m2非自重湿陷性黄土地基的施工中得到广泛的应用,取得了良好的效果.

Based on researching achievements on collapsible loess the prevail collapsible loess foundation treatment method has been adopted in construction industry especially in expressway construction. Ningxia Communications Department decides to use impact roller to deal with foundation in self-weight collapsible loess area. Large amount of testing data has been obtained through dynamic consolidation method being adopted for treating non-self-weight collapsible loess foundation located in Taoshankou -Tongxin sections under Yinchuan - Wuhan Expressway in Ningxia, which eradicates collapsibility of loess and improves the foundation loading capacity. After the highway construction, according to testing, assessment, and theoretical analysis on non-self-weight collapsible loess, several controlling indexes which are required during the treatment of non-self-weight collapsible loess by impact roller are summarized: (1) when adopting 25 kJ impact roller, 40 times of impact rolling is proper, the controlling depth more than 0 ~ 90 cm, compaction degree more than 90%; (2) average settlement volume is more than 25 cm, the average void ratio less than 0.55, and the collapsibility of foundation within 0 ~ 200 cm disappears if 25 kJ impact roller is used for construction. The summary provides reference in the field of highway design, construction and management in some degree. The testing result has been applied in non-self-weight collapsible loess foundation totalled up to 2 227 211 m2 under Tongxin - Guyuan Expressway with 117 km in length and has obtained sound effect.