打桩荷载作用下自由场土体振动衰减规律研究

Research on Vibration Attenuation of Free Field Soil under Pile Driving Load

为研究打桩荷载作用下自由场土体振动衰减规律,建立了考虑桩-土相互作用的二维有限元数值模型,并通过Lamb问题解析解验证了数值模型的有效性。通过分析打桩深度、土体阻尼比、打桩荷载等级和土质条件等因素的影响,研究了土体表面振动特性及振动衰减规律。参数分析表明,打桩深度对微振动的影响较小,在距振源一定距离处的土体表面振动响应基本保持一致;土体阻尼比对土体表面振动的影响显著,阻尼比越小,土体表面振动响应越剧烈;不同场地软硬条件影响微振动的限制距离,在一定距离范围内,土质越软,土体表面振动响应越显著,防振距离越长。基于参数分析结果,对峰值速度衰减曲线进行拟合,拟合公式计算结果与模拟结果较吻合,可为振动敏感建筑场地的选择提供参考。

In order to study the propagation and attenuation law of pile driving vibration load in free field soil, a two-dimensional finite element numerical model considering pile-soil interaction is established, and the validity of the numerical model is verified by analytical solution of Lamb problem. By analyzing the influence of factors such as pile depth, soil damping ratio, pile load level, and soil condition, the characteristics of soil surface vibration and the law of vibration attenuation are studied. The parameter analysis shows that the impact of pile driving depth on microvibration is small, and the vibration response of the soil surface is basically the same at a certain distance from the vibration source;The soil damping ratio has a significant effect on the soil surface vibration, with the decrease of the damping ratio, the vibration response of the soil surface becomes more severe;different soil conditions affect the limit distance of the microvibration, within a certain distance, the softer the soil quality, the more significant the vibration response of the soil surface, and the longer the vibration-proof distance.Based on the above-mentioned parameter analysis results, the peak velocity attenuation curve is fitted, and the settlement result of the fitting formula is in good agreement with the simulation result, which can provide a reference for the selection of vibration-sensitive building sites.