Abstract Granite residual soil is widely used as a subgrade material in pavement engineering. Previous studies have not investigated the influence of stress on the soil water retention curve for this type of unsaturated soil or its significance for predicting ground settlement. Thus, the aims of the present study were: (i) to experimentally investigate the water retention curves for granite residual soil at various stress levels and under different degrees of compaction; and (ii) to numerically explore the influence of stress-dependent water retention on the suction distribution and ground settlement during both rainfall and evaporation periods based on coupled seepage and deformation analyses. The experimental results showed that the applied vertical stress (from 0 to 90 kPa) decreased the retained water content by up to 13% when the suction was less than 200 kPa. The reduction in the retained water content was much more obvious when the degree of compaction decreased from 100% to 85%. The effects of stress on the water retention curves were almost negligible when the suction was higher than 200 kPa, regardless of the degree of compaction. The numerical results showed that the current analysis considering the influence of stress on water retention could predict a higher ground heave and a larger ground settlement, compared with the conventional method without stress effects. This was because the current analysis captured the larger suction reduction during rainfall and higher suction increase during evaporation. The ground deformation became larger when the rainfall intensity increased while the corresponding rainfall duration decreased under the same return period of rainfall. This study implied that the method employed in the present study was more scientific and conservative for assessing ground settlement in pavement engineering.

中文翻译：

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花岗岩残余土的应力依赖性保水及其对地面沉降的影响

摘要 花岗岩残渣土在路面工程中被广泛用作路基材料。以前的研究没有研究应力对这类非饱和土的土壤保水曲线的影响或其对预测地面沉降的意义。因此，本研究的目的是：(i) 实验研究在不同应力水平和不同压实度下花岗岩残余土的保水曲线；(ii) 基于耦合渗流和变形分析，数值研究应力依赖的保水量对降雨和蒸发期间吸力分布和地面沉降的影响。实验结果表明，当吸力小于200 kPa时，施加的垂直应力（0～90 kPa）使滞留水含量降低了13%。当压实度从100%降低到85%时，保留水含量的降低更为明显。无论压实程度如何，当吸力高于 200 kPa 时，应力对保水曲线的影响几乎可以忽略不计。数值结果表明，与没有应力影响的传统方法相比，当前考虑应力对保水影响的分析可以预测更高的地基隆沉和更大的地面沉降。这是因为目前的分析捕获了降雨期间更大的吸力减少和蒸发期间更大的吸力增加。在相同的降雨重现期下，随着降雨强度的增加，地面变形变大，而相应的降雨历时则减少。本研究表明，本研究采用的方法对路面工程中的地面沉降评估更为科学和保守。