ISSN 1000-3665 CN 11-2202/P

    正负压耦合下的多因素影响软基超孔隙水压力变化规律

    Changes in super pore water pressure in soft ground under multi-factor influences coupled with positive and negative pressure

    • 摘要: 真空堆载联合预压法被广泛应用于加固软土地基,预压过程会出现正负压耦合效应,加固软基效果受多种因素影响,如排水板间距、真空作用强度、真空预压时长、堆载间歇时间等,以往的研究集中于单因素分析,未充分考虑多种因素对软基超孔压变化规律的影响。本文在建立并验证真空堆载联合预压加固软土地基有限元分析模型基础上,依据数值模拟结果研究了排水板间距d、真空预压时长Tv、真空作用强度Pv、堆载间歇时间Ti等施工参数对超孔隙水压力的影响,探讨了正负压耦合下的多因素影响超孔隙水压力变化规律。结果表明:当排水板间距由0.9 m增至1.0 m时超孔隙水压力增加得更加明显,考虑到排水效果及经济性,建议排水板间距取0.9 m;随着Pv的增加,连续堆载后软基中的超孔隙水压力峰值基本上呈线性下降趋势;延长Ti时软基中的超孔压均呈下降趋势,Ti>15 d后超孔压变化已不明显,建议间歇时间为15 d;Tv仅对初期堆载的超孔隙水压力产生影响;排水板间距、真空作用强度、堆载间歇时间对预压过程中超孔压有较大影响。研究成果可为真空联合堆载预压处理的设计和施工提供科学依据。

       

      Abstract: Vacuum stacking joint pre-compression method is widely used to reinforce soft ground, with the preloading process generating a coupling mechanism involving both positive and negative pore pressure, the effect of this method to reinforce soft ground is affected by many factors, such as the spacing of drainage board spacing, vacuum intensity, vacuum preloading duration, and interval time. Previous studies focused on single-factor analysis, failing to adequately account for the coupled effects of multiple factors on the super pore water pressure in soft ground. Based on the establishment of finite element model and verification, based on the calculation results of the study of drainage board spacing d, vacuum intensity Pv, vacuum preloading duration Tv, interval time Ti and other construction parameters on the super pore water pressure, to explore the positive and negative pressure coupling multi-factor influence of the super pore water pressure change rule. The results show that: when the spacing of the drainage board increased from 0.9 m to 1 m, the increase in super pore water pressure is more obvious, and the spacing of the drainage board is recommended to take 0.9 m considering the drainage effect and economic benefit; with the increase in Pv, the peak of the super pore water pressure produced in the soft foundation after continuous stacking basically shows a linear and gradual decline; with the increase in Ti, the super pore water pressure produced in the soft foundation is basically decreased gradually. The super pore pressure generated in the soft ground shows a decreasing trend, and the change in the super pore pressure is not obvious if Ti>15 d, so it is suggested that the interval time is 15 d; Tv only affects the super pore water pressure at the initial load stage; drainage board spacing, vacuum intensity, interval time significantly influence the super pore water pressure evolution during preloading process. The research results provide a scientific basis for the design and construction of vacuum-surcharge preloading treatment.

       

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