基于三维连续‑离散耦合模型的门架式双排抗滑桩受力分析

Force Analysis of Frame Type Double Row Anti Slide Piles Based on Three Dimensional Continuous Discrete Coupling Model

摘要:

使用结构力学计算模型分析门架式双排抗滑桩内力变形，由于引入简化假定在实际工程中存在一定局限。 依托湖北省巴东县某建筑边坡工程，以FLAC3D和PFC3D为工具建立包含门架式双排抗滑桩结构和边坡的三维连续-离散耦合分析模型，采用重力增加法获取给定安全系数下的门架式双排抗滑桩的内力变形，并通过对比分析明确排距、桩距和桩径对内力变形的影响。研究表明，连续-离散耦合模型可有效获取桩后土体潜在滑移趋势并考虑桩土相互作用。前后排桩弯矩分布呈现“S”型曲线特征，且前排桩承受更大弯矩。前后排桩侧向位移总体上均由桩底向上逐步增大，前排桩略大于后排桩，但由于连梁约束作用前排桩侧向位移在近桩顶处减小。给定安全系数增大会导致前后排桩弯矩增大和侧向位移非线性增长。排距增大后，前排桩桩顶负弯矩增大，前后排桩桩身正弯矩减小、负弯矩增大。桩距增大对桩顶弯矩影响较小，但会导致前后排桩桩身正弯矩和负弯矩均增大。桩径增大后，后排桩桩顶正弯矩增大，前排桩正弯矩和负弯矩均增大，后排桩正弯矩增大而负弯矩减小。

Abstract:

Computational models based on structural mechanics are used to analyze the internal forces and deformation of the frame-type double-row anti-slide piles. However, due to simplified assumptions, they have certain limitations in practical engineering applications. Based on a slope engineering project in Badong County, Hubei Province, a three-dimensional continuous-discrete coupling analysis model that incorporated frame-type double-row anti-slide piles and the slope was established using FLAC3D and PFC3D. The gravity increase method was employed to analyze the internal forces and deformation of double-row piles under a given safety factor, and a comparative analysis was conducted to clarify the effects of row spacing, pile spacing, and pile diameter on the internal forces and deformation. The results showed that the continuous-discrete coupling model effectively captured the potential slipping trend of soils behind piles and considered the interaction between piles and soils. The bending moment distribution of the front and back rows of piles exhibited an S-shaped curve, with the front row pile experiencing larger bending moments. The lateral displacements of both front and back rows of piles generally increased gradually from the bottom to the top, with the front pile exhibiting slightly higher displacement than the back row pile. However, due to the constraint effect of the coupling beam, the lateral displacement of the front row pile decreased near the pile top. An increase in the safety factor resulted in an increase in both bending moments and a nonlinear growth in lateral displacements. Wider row spacing led to higher negative bending moments at the top of the front row of pile, while the positive bending moments decreased and the negative bending moments increased for both front and back rows of piles. Increasing pile spacing had little effect on the bending moments at the pile tops, but it resulted in an increase in both positive and negative bending moments for both rows. Larger pile diameters led to an increase in positive bending moment at the top of the back row pile, as well as increases in both positive and negative bending moments for the front row pile. The positive bending moments of the back row pile increased, while the negative bending moments decreased.