动载作用下桶形基础周围土体变形的数值模拟

NUMERICAL SIMULATION ON SAND STRATA DEFORMATION AROUND BUCKET FOUNDATION UNDER DYNAMIC LOADINGS

针对动冰载作用下桶形基础周围土体的液化变形进行了数值模拟。建立饱和砂层中桶形基础的简化计算模型,研究动载作用下砂层竖向和水平向的液化变形。首先与桶形基础动载离心机试验比较,验证了计算模型的可靠性。分析了砂层竖向和水平向液化变形特征,以及砂层变形随动载特性和土性参数变化的规律。研究结果表明:砂层变形随着动载频率减小、振幅加大、砂层弹性模量降低而增大。在该文计算模型和荷载条件下,砂层竖向最大变形发生在距荷载作用边界0.25倍桶高位置处,水平最大变形发生在荷载作用边界处。当动载激振时间超过5h后,土顶面竖向变形约为土底面竖向变形的3倍,距荷载作用边界2.0倍桶高位置处的水平变形仅为荷载作用边界处水平变形的3.3%。

The liquefaction deformation of sand strata around bucket foundation is simulated under equivalent dynamic ice-induced loadings. A simplified numerical model has been presented for bucket foundation in saturated sand strata. The vertical and horizontal liquefaction deformations under dynamic loading are studied. Firstly, the numerical model and results are verified through a comparison with the centrifuge test results. Secondly, the development characteristics of liquefaction deformation are analyzed. The following results are obtained from numerical simulations： the liquefaction deformation of sand strata increases with the increase of the dynamic loading amplitude, but decreases with the increase of the frequency and elastic modulus. The maximum vertical deformation occurs at the surface which is 0.25 times of bucket’s height apart from the loading boundary. The maximum horizontal deformation occurs at the loading boundary. When the dynamic loadings lasts for more than 5 hours, the vertical deformation at the top surface is 3 times of that at the bottom, and the horizontal deformation at the surface which is 2.0 times of bucket’s height apart from the loading boundary is 3.3% of that at the loading boundary.