风积沙地基装配式偏心基础抗拔试验研究

在毛乌素沙漠中开展装配式偏心基础在上拔、上拔+水平力组合荷载作用下的现场试验研究。根据试验加载过程中监测的基础顶部位移、地表竖向位移及基础底板土压力数据，分析基础顶部的荷载-位移特性，研究装配式偏心基础的抗拔承载机制。结果表明，（1）在上拔、上拔和水平力组合作用下，基础顶部上拔和水平位移曲线均呈二阶段的承载特性；（2）当仅受上拔荷载作用时，基础偏心引起的附加弯矩，使得基础底板产生偏转，基础及底板上覆部分沙土自重抵抗上拔荷载，而在上拔和水平力组合荷载工况下，基础偏心引起的附加弯矩小，与上拔荷载工况相比，基础极限抗拔承载力提高8.7％，即在组合荷载工况下装配式偏心基础能够发挥更多的沙土来抵抗上拔荷载；（3）根据装配式偏心基础的抗拔承载机制，引入外荷载合力作用线与支架作用线之间的夹角δ来反映水平荷载对装配式基础抗拔破坏因子的影响，其影响规律为装配式基础的抗拔破坏因子随δ增加而降低。

Field tests on pullout behavior of eccentric grillage foundation in aeolian sand

In MU US desert, full-scale in-site tests on the bearing capacity of eccentric grillage foundations subjected to the uplift and uplift combined with horizontal loading were carried out respectively. The load-displacement both of foundation top plane and ground surface, and the soil pressure acted on the footing slab were measured. The uplift mechanism of foundation was analyzed. The results show that under the uplift, uplift combined with horizontal loadings, the load-displacement of the eccentric grillage foundation presented two-staged behavior. Under uplift load only, the ultimate uplift resistance is assumed to be the sum of the dead weight of foundation and the soil mass contained above the bottom of the assembled slab base. The movement resulted by the eccentricity reduced the uplift bearing capacity of foundation. However, under uplift combined with horizontal loading, the ultimate uplift load increased 8.7 percent by comparison to the uplift load case. It indicate that the eccentric foundation structure is more suitable to the load case of uplift combined with horizontal loading in engineering. The angle δ , the consultant to the line from centroid of slab to top plane , is suggested to reflect the eccentricity and applied loads. According to the test results, the pullout capacity decrease rapidly with the increasing of angle δ.