粗颗粒盐渍土地基掏挖基础抗拔承载模型试验研究

Model tests on uplift behaviors of belled pier foundation in coarse-grained salty soils

考虑不同粗颗粒盐渍土层状态(结晶、溶蚀)和厚度,通过对粗颗粒盐渍土地基掏挖基础进行抗拔承载模型试验,分析了掏挖基础的抗拔承载特征。研究结果表明,上拔加载过程中地面以基础为中心产生明显隆起现象,逐渐形成以基础为中心的环状和放射状裂缝。地面隆起范围近似呈圆形扩大趋势;上拔位移随距基础中心距离增大而不断减小,上拔位移梯度随荷载增加逐渐增大。荷载–位移曲线呈现出典型的"软化型"特征;结晶状态下基础抗拔承载力随着盐渍土层厚度增加显著增加;结晶状态下基础抗拔承载力显著高于溶蚀状态。粗颗粒盐渍土地基破裂面形态表现为分段直线方程形式;普通粗颗粒土层、结晶状态粗颗粒盐渍土层及溶蚀状态粗颗粒盐渍土层上拔角分别约为32°,34°及18°。

Based on the uplift model tests, the uplift working behaviors of belled pier foundation with different thicknesses and crystalline and dissolved states of coarse-grained salty soils are obtained. The results show that the uplift loads lead to obvious ground heave surrounding the belled pier foundation, which induces circumferential and radial cracks in the soils around the foundation. Moreover, the ground heave extent is approximately circular as the uplift loads increase. The uplift displacement decreases with the growing distance from the center of foundation, and the uplift displacement gradient increases with the increasing uplift loads. The load-displacement curves exhibit a typical softening tendency. The uplift bearing capacity of salty soils in the crystalline state increases at larger thickness of coarse-grained salty soils, and is also higher for the salty soils in crystalline state than that for the salty soils in dissolved state. The geometric shape of failure surface can be described by a straight line equation with slope in the underlying coarse-grained soils different from that in the surface salty soils. The uplift angles of the surface salty soils in crystalline and dissolved states are approximately 34°and 18°, respectively, while 32°for the underlying soils without salt.