为寻求经济合理的湿陷性黄土综合管廊基坑挖填界面控渗与地基处理方法,通过管廊现场浸水试验研究了3种界面控渗、5类地基处理措施组合场地的入渗特征与湿陷变形特性。结果表明:挖填界面控渗可弱化界面集中渗透,延迟地基浸湿时间,其中挖填界面表层夯填在控渗效果、造价方面更优;管廊地基沉降模型可用近似线性和双曲线的分段函数表达,模型参数hult为5类管廊场地与海绵设施组合下排渗稳定后的极限沉降量,该值可作为管廊结构与廊内管线设计的沉降容许值;模型参数a为管廊上部压实土增湿引起的地基变形速率,其与振动夯实的地基处理厚度hc呈近似线性相关,hc越大,地基下原状黄土损伤可能越严重,各段管廊实测地基沉降量也越大,管廊地基不宜采用振动压实;薄层水泥土垫层在控制沉降方面效果显著,膨润土防水毯在地基防渗的同时,在控制差异沉降方面效果最好;因此“挖填界面表层夯填控渗+地基土工材料防渗+薄垫层或翻夯”的组合方法对湿陷性黄土区管廊地基变形控制更为经济有效。研究结果可为湿陷性黄土管廊地基处理提供理论支撑。
To explore economically reasonable seepage control measures at the excavation-filling interface and foundation treatment methods for utility tunnels in collapsible loess areas. The infiltration and collapsibility characteristics of the combined site with three types of interface control infiltration and five types of foundation treatment measures were studied through on-site immersion tests of the utility tunnels in this study. The results show that the seepage control measures at the excavation-filling interface can mitigate concentrated seepage and delay the onset of foundation wetting. Surface compaction proves to be the most cost-effective method for seepage control. The model of foundation settlement can be described as an approximate linear and hyperbolic function segments. The hult is the ultimate settlement of the combination of 5 types of utility tunnel sites, which can be used as the allowable settlement values for the design of utility tunnel and pipelines. The deformation rate 'a' of the foundation, caused by the upper compacted soil wetting, exhibits an approximately linear correlation with the hc of the foundation treatment by vibration compaction. A larger hc suggests more severe damage to the original loess beneath the foundation and a greater measured settlement of the utility tunnel, indicating that vibration compaction is unsuitable for utility tunnel foundation treatment. The thin cushion layer significantly affects settlement control, while the bentonite waterproof blanket effectively reduces differential settlement and provides foundation waterproofing. Consequently, the combined methods of "surface compaction for seepage control at the excavation-filling interface, foundation anti-seepage using geotechnical materials, and either a thin cushion layer or overturning compaction" is the most cost-effective in controlling the deformation of utility tunnel foundations in collapsible loess areas. The research results offer theoretical support for the foundation treatment of utility tunnels in collapsible loess sites.
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