竖向直排冻结条件水平冻胀力试验研究

竖向直排冻结方式常用于软弱地层中斜井掘进和深基坑止水帷幕的冻结法施工中,目前国内外对该冻结方式下水平冻胀力的分布研究鲜见报导。以某斜井冻结工程为背景,推导出温度场、应力场和水分场等相似模拟准则,设计了竖向直排冻结模型试验并细化具体试验方案,利用大型三维模拟冻结试验系统,对竖向直排冻结条件下不同深度土体的水平冻胀力分布特性进行了试验研究。结果表明,竖向直排冻结过程中埋深对水平冻胀力的影响明显,在其他条件相近的情况下同一水平面中水平冻胀力的大小与温度密切相关;冻胀力的变化率主要受冻结锋面位置的影响,距离冻结锋面较近时冻胀力的变化率逐步达到峰值;已冻土体的冻胀力随冻结锋面向外发展而趋于平稳。

Experimental research on horizontal frost heaving force of vertical straight freezing

In order to reinforce the loose, high moisture and unstable strata in the underground engineering artificial freezing method was commonly used, and vertical straight layout of the frozen pipes was used frequently. However, the distribution and changes of temperature, stress and displacement were completely different from vertical circular layout, thereby induced engineering stability problems were paid less attention, which need further investigation both at home and abroad. On the basis of an inclined shaft freezing construction, the similarity criteria in the vertical straight freezing process were derived, which contained temperature field, stress field and moisture field, etc. Specific experiment program during the total process of soil freezing was designed detailedly. In self-made three-dimensional simulation freezing experiment system, 20 vertical frozen pipes were layout as 4×5 form. Stress environment and seepage condition were simulated as possible as field conditions. The value and change rate of soil temperature and horizontal frost heaving force were measured during the process of soil freezing. On this basis, the distribution of soil temperature and horizontal frost heaving force in different depth were investigated. Experiment results show that in vertical straight freezing, the impact of soil depth on the horizontal frost heaving force is significantly. In the same depth and ignoring the impact of other conditions, the value of frost heaving force and soil temperature are closely related; the change rate of frost heaving force mainly depends on the location of freezing front, which reaches its peak gradually by the distance close to freezing front; while the horizontal frost heaving force in frozen soil has stabilized with the development of freezing front.