考虑建筑物荷载的砂性土天然地基附加应力分析

Analysis on additional stress of natural sandy soil foundation considering building load

基坑开挖会打破周边土体原有的应力状态,产生应力重分布并出现土体附加应力,进而影响周边地层的稳定性。以Mindlin解为基础,将基坑开挖卸荷和建筑物附加荷载分别引起的邻近建筑物砂性土天然地基附加应力进行叠加,得出了基坑开挖引起的邻近建筑物砂性地基的附加应力分布公式。基于提出的公式,并利用Matlab编程计算分析了不同建筑物附加荷载和不同基坑开挖距离组合条件下,基坑开挖引起的天然地基附加应力变化规律。研究结果表明:地基附加应力的增长比例与附加荷载的增量呈线性关系,附加荷载每增加100 kPa,地基附加应力增加36%;同一深度处天然地基的三向附加应力最大值基本处在同一范围内,最大值位置均在建筑物左侧壁附近。

The excavation of foundation pits will break the original stress state of the surrounding soil and produce stress redistribution and additional stress in the soil, which will affect the stability of the surrounding strata.In this paper, based on the Mindlin solution, the additional stresses in the natural sandy soil foundation of an adjacent building caused by the excavation unloading and the additional loading of the building are superimposed, and an additional stress distribution formula of the sandy foundation of the adjacent building caused by the foundation excavation is derived.The changing law of additional stress of natural foundation caused by different combination of distances of foundation excavation and building additional loads is calculated and analyzed by using Matlab programming.The results show that:(1) The increment ratio of additional stress of the natural foundation is linear with the increment of additional load, and the additional stress of natural foundation increases by 36% for per 100 kPa increment of additional load;(2) At the same depth, the maximum values of positive additional stress, lateral additional stress and vertical additional stress of the natural foundation are basically in same range of the soil foundation, and the maximum value is located near the left wall of the building foundation.