软弱地层隧道不同桩基设计参数的对比研究

Comparative Study on Design Parameters of Pile Foundation for Tunnel in Soft Strata

为了系统研究在隧道开挖、支护过程中不同桩基设计参数对地层力学行为的影响规律,运用数值分析方法,通过分别改变桩基的桩长、桩径、桩间距和桩土刚度比,对比分析地层竖向位移及应力变化规律,并对桩基设计参数进行比选优化。研究结果表明:在一定范围内,桩长越长,桩径越大,桩间距越小,相应的地层竖向位移越小且第一主应力也越小;在桩长、桩径、桩间距一定的情况下,仅考虑弹性模量对其影响时,桩土刚度比越大,地层竖向位移越大,桩基轴力增大趋势越明显。

In order to research the rule how the pile foundation＇s design parameters affect the mechanical behavior of strata in the process of tunnel excavation and supporting systemically, this paper, by numerical analysis, compared and then analyzed the laws of the vertical displacement of strata and the stresses by changing the pile length, pile diameter, pile spacing and stiffness ratio of pile and soil, respectively, then made comparison and optimization between these design parameters. The result shows that, in certain range, longer, bigger piles with smaller space leads to the smaller vertical displacement of strata and the less first main stress accordingly ; and on the condition of given pile length, diameter and spacing with only the effect of elastic modular taken into consideration, the larger stiffness ratio of pile and soil with larger vertical displacement leads to the more significant increase tendency of the pile＇s axial force.