结构性土体的施工扰动及其对沉降的影响

Field disturbance of structured clay and its effect on settlements of soil foundation

天然结构性土体在工程实践中易受扰动,导致结构强度降低,工程性质改变。这种施工过程中土体受到的原位施工扰动有别于现场取土、应力释放等引起的试样扰动;在天然土体原位扰动机理的分析研究基础之上,提出了针对原位扰动土的折线形原位压缩曲线。根据天然结构性土体e–lgp'曲线以结构屈服应力和转折应力为界的分段特性,考虑加载过程中压缩性的变化,结合工程实例的计算,讨论施工扰动度的评价,介绍如何利用原位压缩曲线以及扰动后土体的压缩曲线计算地基的最终沉降,分析原位扰动引起的最终沉降变化规律。结果表明:本文提出的方法合理地预测了施工扰动对最终沉降的影响。

Natural soil was prone to be disturbed. The structural strength consequently was reduced and the engineering properties changed. The field disturbance during construction, such as the installing of vertical drain, was distinct from the sample disturbance. Based on the mechanism of field disturbance, a new method for modifying the compression curve of disturbed soil was developed. Then, the evaluation of the field disturbance degree was discussed associated with the results of the vane test in situ. Furthermore, the additional settlement due to the field disturbance and the compression behavior of disturbed soil were analyzed considering the varied structural strength with depth and varied compressibility during the process of loading. The computed results of typical examples indicated that settlements due to field disturbance could be predicted by the proposed method and the field disturbance had a significant influence on the compressibility of natural soils, which should be emphasized in practice.