高级检索

梯形循环荷载下成层土中不排水桩复合地基固结分析

Consolidation Analysis of Impervious Pile Composite Foundation Considering Soil Stratification Under Trapezoidal Cyclic Loading

  • 摘要: 在软土地区的仓储堆场、交通路基等工程中,地基土常承受兼具恒载维持和间歇特征的循环荷载,其长期性能与固结变形直接影响工程安全。然而,现有复合地基研究多侧重均质地基或单一加载模式,对复杂循环加载下的固结响应研究仍不充分。为此,本文基于等平均应变假设,建立考虑土体成层性的不排水桩复合地基固结控制方程,采用傅里叶级数表征包含加载、持载、卸载和间歇阶段的梯形循环荷载,推导超静孔隙水压力和有效应力解析解。研究结果表明:影响区与桩径比值越大,土体承担荷载比例上升,有效应力峰值增大但波动幅度减小。在相同峰值荷载下,矩形、梯形和三角形循环荷载所产生的有效应力峰值呈依次递减趋势。这一差异源于三者荷载时程的平均应力水平及峰值持时不同,具体而言,梯形荷载较矩形荷载下降约21%,三角形荷载较矩形荷载下降约46%。加载周期延长提高有效应力峰值,而间歇期延长促进孔压消散并降低有效应力累积水平。

     

    Abstract: In engineering projects such as storage yards and roadbeds in soft soil areas, foundation soils often bear cyclic loads with both constant load maintenance and intermittent characteristics, where their long-term performance and consolidation deformation directly affect engineering safety. However, existing composite foundation research primarily focuses on homogeneous soils or single loading modes, leaving insufficient investigation into consolidation responses under complex cyclic loading. To address this, this paper establishes a consolidation control equation for undrained pile composite foundations considering soil stratification based on the equivalent average strain assumption. Using Fourier series to characterize trapezoidal cyclic loads encompassing loading, holding, unloading, and intermittent phases, analytical solutions for excess pore water pressure and effective stress are derived. The findings reveal that a larger influence zone-to-pile diameter ratio increases the proportion of load borne by the soil, leading to higher effective stress peaks but reduced fluctuation amplitude. Under identical peak loads, the effective stress peaks generated by rectangular, trapezoidal, and triangular cyclic loads exhibit a sequential decreasing trend. This difference stems from variations in average stress levels and peak duration across the three loading patterns, specifically with trapezoidal loads decreasing by approximately 21% compared to rectangular loads and triangular loads declining by about 46% relative to rectangular loads. Prolonging the loading cycle elevates effective stress peaks, while extending the intermittent period facilitates pore pressure dissipation and reduces effective stress accumulation levels.

     

/

返回文章
返回