透明黏土模型中螺旋锚旋转沉贯和上拔力学特性试验研究

    Experimental Study on the Mechanical Behavior of Helical Anchors during Installation by Rotation and Uplift in Transparent Clay Models

    • 摘要: 螺旋锚具有施工便捷、承载力高、可重复利用等优点,然而目前针对黏土中螺旋锚旋转沉贯机理及其对上拔承载力学特性的研究较少。基于气相二氧化硅N20材料配制的透明黏土和PIV图像处理技术,开展了螺旋锚旋转沉贯及上拔承载变形透明黏土室内模型试验、数值模拟分析及极限承载力理论推导,研究结果表明:螺旋锚旋转沉贯后叶片上方会产生回淤现象,施加上拔荷载后叶片下方土体会出现回落现象。螺旋锚的荷载-位移曲线均先陡增后缓增,随着埋深比、叶片数量、叶片间距、先期固结压力以及沉锚休止时间的增加,螺旋锚的极限承载力均呈增大趋势,且沉锚休止时间对极限承载力的影响存在临界值。螺旋锚的极限抗拔承载力因数随着δrem的减小和Xd的扩大而减小,且其抗拔承载力因数N随埋深比变化的规律与不考虑安装效应时相同,都表现为先急剧增长再趋于稳定,简化的土体破坏模型推导的极限抗拔承载力因数与数值模拟吻合度较高。

       

      Abstract: Helical anchors offer advantages including convenient construction, high bearing capacity, and reusability; however, research on their rotational installation mechanism in clay soils and the resulting uplift bearing behavior remains limited. Utilizing transparent clay synthesized from fumed silica N20 material and Particle Image Velocimetry (PIV) image processing technology, laboratory model tests on rotational installation and uplift-induced deformation in transparent clay were conducted, complemented by numerical simulation analysis and theoretical derivation of ultimate bearing capacity. The research findings indicate: following rotational installation, soil backflow occurs above the helical plates, while soil subsidence develops beneath the plates upon application of uplift load. The load-displacement curves consistently exhibit an initial steep increase followed by a gradual rise. The ultimate bearing capacity of helical anchors increases with higher embedment depth ratio, greater number of helical plates, larger plate spacing, increased pre-consolidation pressure, and longer setup time after installation, with the influence of setup time exhibiting a critical threshold. The ultimate pullout capacity factor decreases with a reduction in the remoulded interface friction angle ratio (δrem) and an increase in the sensitivity parameter (Xd). The variation pattern of the pullout capacity factor (N) with embedment depth ratio aligns with that observed when installation effects are disregarded, characterized by rapid initial growth followed by stabilization. The ultimate pullout capacity factor derived from a simplified soil failure model demonstrates close agreement with numerical simulation results.

       

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