沉井在不同真空预压处理程度的软土地基中下沉阻力特征研究

目前国内外暂无沉井基础与真空预压处理技术结合的研究。试验通过模型来模拟沉井在不同真空预压处理程度的软土地基中的下沉，对沉井侧摩阻力、刃脚底部阻力进行分析，并通过数值模拟进行对比分析，这对实际工程与理论研究都有参考意义。试验结果表明:随着真空预压处理时间的增加，沉井在软土地基中下沉时的侧摩阻力逐渐增加，靠近刃脚附近侧摩阻力减小的趋势消失；刃脚底部的土压力随着沉井下沉缓慢减小，其中刃脚斜面的土压力占比较工程实际偏大；在软土基础中沉井自重荷载在真空预压处理后提高了250%，且当含水率降低到45%左右时，沉井自重荷载有明显的提升；现有理论计算方式对于刃脚踏面的竖向受力计算偏大，对于刃脚斜面的竖向受力计算偏小。

Study on subsidence resistance characteristics of caisson in soft soil foundation with different vacuum preloading degree

At present, there is no research on combination of caisson foundation and vacuum preloading treatment at home and abroad. The model test was used to simulate the sinking of the caisson in the soft soil foundation with different vacuum preloading degree, and the sidewall friction and the bottom resistance of edge foot were analyzed and contrasted with numerical simulation. This has reference significance for theoretical research and practical engineering design. The result shows that with the increase of vacuum preloading time, the sidewall friction of caisson when sinking in soft soil foundation gradually increases, and the tendency of reducing the sidewall friction near the edge foot disappears. The earth pressure at the bottom of the blade foot decreases slowly with the sinking of the caisson, and the proportion of the earth pressure on the incline of the blade foot is larger. After vacuum preloading treatment, the dead load of caissons in soft soil foundation is increased by 250%, and when the moisture content is reduced to about 45%, the dead load of caissons is increased significantly The existing theoretical calculation method is too large for the vertical force calculation of the blade tread, and the vertical force calculation for the blade incline is too small.