某市政道路路基砂土液化与软土震陷的判别及处理  

Discrimination and treatment of sand liquefaction and seismic settlement of soft soil in an urban road subgrade

作　　者：管星宇 GUAN Xing-yu(Shanghai Urban Construction Design&Research Institute(Group)Co.,Ltd.,Shanghai 200125,China)

机构地区：[1]上海市城市建设设计研究总院(集团)有限公司,上海200125

出　　处：《地基处理》2023年第1期76-81,共6页Journal of Ground Improvement

摘　　要：路基在地震时可能发生液化、震陷等震害,当前市政道路设计的相关规范尚未对路基提出抗液化、震陷的具体要求。本文对某市政道路地基土层液化程度、震陷量进行分析,并提出地基抗液化措施,为其他类似工程提供参考。场地同时存在较厚的砂土及软土层,标准贯入试验结果表明砂土液化指数为6.9~40.8,地基存在严重液化土层,参照现行规范或规程分别对砂土、软土震陷量进行估计,结果表明当路堤高度为3 m,按不利情况估计的震陷量约为250~350mm,其中70%以上产生于淤泥质软土层。根据路基特性及震害修复条件,结合既有经验,下卧软土层震陷通常不需专门处理;对于液化土层,当路基达到由路堤高度、上覆非液化土层厚度、地下水位深度及液化土层累计厚度确定的抗震设计界限时,需采取抗液化措施,对于较厚液化土层可采用振冲碎石桩处理。Liquefaction and seismic subsidence of subgrade may occur during earthquake. At present, the relevant specifications of municipal road design have not yet put forward specific requirements for roadbed resistance to liquefaction and seismic subsidence. This paper analyzes the soil liquefaction degree and seismic subsidence of a municipal road foundation, and proposes the anti-liquefaction measures of the foundation to provide reference for other similar projects. There are thick sandy soil and soft soil layers on the site, the results of standard penetration test show that the liquefaction index of sandy soil layer is 6.9~40.8, which indicates that there is serious liquefaction soil layer in the foundation. The seismic subsidence of sandy soil and soft soil layers is estimated respectively according to the current code and specification. The results show that when the embankment height is 3 m, the estimated seismic subsidence is about 250~350 mm according to the unfavorable conditions, and more than 70% of it occurs in the mucky soft soil layer.According to the characteristics of the subgrade and the repair conditions of earthquake damage, combined with the existing experience, the earthquake subsidence of the underlying soft soil layer usually does not need special treatment. For the liquefied soil layer, when the subgrade reaches the seismic design limit determined by the height of the embankment, the thickness of the overlying non-liquefied soil layer, the depth of the groundwater table and the cumulative thickness of the liquefied soil layer, anti-liquefaction measures shall be taken. For thicker liquefied soil layers, vibrofloatation stone column can be used.

关 键 词：市政道路 路基 砂土 液化 软土 震陷 振冲碎石桩 

分 类 号：U447[建筑科学—桥梁与隧道工程]