车辆荷载对支护桩主动土压力的影响分析

通过现场车辆加载试验,测定加载过程中产生的加速度及桩后土压力,分析车辆的振动特性,得到了振动加速度随时间变化的关系式。进而基于极限平衡分析理论,得到了车辆荷载作用下桩后主动土压力的计算表达式,并讨论了水平振动加速度系数、土体内摩擦角、土体重度及桩–土外摩擦角对桩后主动土压力大小和分布的影响。结果表明:车辆行驶速度越大,引起的响应峰值加速度越大,产生的动土压力幅值越大。当车速相同,加载车辆与桩间距越大,产生的动土压力值越小。通过对文中车辆荷载作用下桩后主动土压力计算公式的验证,发现实测土压力值与理论分析结果吻合较好。因此,该土压力计算公式可作为车辆荷载作用下支护桩后主动土压力的计算依据。

Effects of active earth pressure on supporting piles under vehicle loads

Through field loading tests on vehicle, the acceleration under loading conditions and soil pressure behind piles is determined, an equation for the vibration acceleration changes over time is obtained, and the vibration characteristics of the vehicle are analyzed. Based upon the limit equilibrium method, a method is proposed for calculating the dynamic earth pressure on piles under vehicle loading. The effects of a wide range of parameters like vibration acceleration coefficient, wall friction angle, soil friction angle, and the weight of the soil on the active earth pressure are studied. The results show that the peak acceleration and the amplitude of dynamic soil pressure increase with increasing vehicle speed. When the speed is the same, the dynamic soil pressure is attenuated very fast with the spacing between the loading vehicle and the pile, which is changed in a sinusoidal fashion. Through validation, it is indicated that the measured earth pressure accords with the theoretical analysis. Therefore, the proposed method may provide a basis for the calculation of active earth pressure on supporting piles under vehicle load.