湿陷性黄土地区风机基础单桩静载浸水试验探讨

Static Load Immersion Test of Single-pile for Wind Turbine Pile Foundation in Collapsible Loess Area

我国现行湿陷性黄土地区建筑规范中关于浸水试验浸水总量或浸水程度的要求比较模糊,在山地风电场,若采用湿陷土层全部浸水饱和的浸水试验结果指导设计,将导致设计偏保守。结合甘肃某风电场风机基础钻孔灌注桩静载浸水试验,设置了4种浸水状态,分别进行单桩竖向承载力试验。结果表明:大浸水状态桩基承载力仅为设计值的60%~70%,其余3种状态桩基承载力均大于设计承载力;设计承载力作用下,小浸水与中浸水状态,桩顶沉降变形基本一致;小浸水状态的实测入渗深度为3. 5m;依据小浸水试验结果优化桩基设计,经风电场运行验证,结果是合理的。

In the current building code of collapsible loess area in China,the requirement of total amount of water or degree of immersion in immersion test is vague. In mountainous wind farm,the design will be conservative if the results of immersion test which all collapsible soil saturated was used to guide the design. Based on the static load immersion test of Bored Piles in a wind farm in Gansu province,four kinds of immersion states have been considered,the vertical bearing capacity test of single pile was carried out respectively. The results show that the bearing capacity of piles in the large immersion state is only 60% ~ 70% of the design value,and the bearing capacity of the other three states is higher than the design value; under the design load,the settlement deformation of pile top is basically the same in the small immersion and middle immersion state; the measured depth of infiltration in the small immersion state is 3. 5 m. The pile foundation design based on the results of small immersion test is reasonable after years of verification by wind farm operation.