水泥固化的风积沙地基扩展基础抗拔试验研究

Uplift load tests on model spread foundations in cement-stabilized aeolian sand

沙漠风积沙地基结构松散、稳定性差、承载力低,利用水泥作为固化剂固化稳定风积沙,形成水泥固化风积沙地基是改善其不良工程特性的有效手段。将取自内蒙古库布齐沙漠的现场风积沙重塑为3%含水率的试验用风积沙,向其中掺入6%普通硅酸盐水泥经充分拌和形成水泥固化风积沙填料,完成了水泥固化风积沙地基中9个扩展基础模型抗拔试验。结果表明,风积沙水泥固化方法可显著提高风积沙抗拔承载性能。上拔荷载作用下,当水泥固化风积沙扩展基础抗拔深度与底板边长比值小于3.5时,其荷载–位移曲线呈2阶段变化:初始弹性段—峰值荷载、峰值荷载后破坏段,极限抗拔承载力对应的位移与底板边长比值变化范围为0.04%~1.05%,平均0.54%。按"土重法"确定的水泥固化风积沙"上拔角"远大于天然风积沙。

Aeolian sands are inherently very low in strength and very high in compressibility because they are loose, cohesionless and easily movable. The cement-stabilization of aeolian sand may be an alternative method to improve the mechanical characteristics of aeolian sand in the desert areas. In this study, the aeolian sand samples collected fi＇om the Hobq Desert are remoulded with a moisture content of 3%, and a relatively small amount of cement of 6% by weight of dry aeolian sand is added to the aeolian sand backfill. A total of 9 uplift load tests are carried out to investigate the uplift performance of model spread foundations embedded in cement-stabilized aeolian sand. The experimental results demonstrate that the cement-stabilized aeolian sand has a typical brittle nature, and two-phase pre-peak and post-peak behaviours of load-displacement responses are observed in all the tests on the model spread foundations embedded in the cement-stabilized aeolian sand. Under uplift loading, when the normalized embedment ratio of depth to basement width for spread foundations is less than 3.5, the displacement corresponding to the ultimate uplift resistance ranges fi＇om 0.04%~1.05% of the basement width, with an average of 0.54%. Based on the uplift capacity of shallow spread corresponding to the peak failure resistances, the magnitudes of the slope angle a of the dead weight method are calculated for each of the spread foundations. Compared to the natural aeolian sand, the significant increases in uplift resistance and slope angle a of the dead weight method can be obtained for model spread foundations subjected to uplift in the cement-stabilized aeolian sand, irrespective of embedment ratios of H/D.