【摘要】 为研究黄土阶梯式斜坡的场地效应,选取宝兰客专通渭—秦安某路堤段阶梯式斜坡为研究对象进行现场测试和数值分析。对测试加速度时程从时域和频域2方面进行分析,研究不同列车对各阶梯田的振动特性的影响,研究结果表明:随着与轨道中心距离的增大,振动加速度峰值基本呈衰减趋势,但在第4阶梯田位置出现明显的振动反弹增大;各阶梯田处的加速度峰值和振动加速度级受到列车速度的影响,但由于振动放大区的存在,使得第3～5阶梯田处的加速度峰值在列车速度较小时,达到最大值;通过1/3倍频程分析,振动放大区主要对中心频率为1～10 Hz的成分进行放大。建立路基-地基-阶梯式斜坡模型,研究地基和各阶梯田土体弹性模量变化对振动的影响,发现在列车荷载和重力耦合作用下,使得各阶梯田边缘位置的最大位移和Mises应力大幅增大;地基土体弹性模量变化对各阶梯田处的振动都有明显的影响,而阶梯田土体弹性模量变化只对该阶和相邻前后2阶梯田的振动有影响,对远离该阶梯田处的振动基本无影响。更多还原

【Abstract】 In order to study the site effect of stepped loess slope, field test and numerical analysis were carried out on a stepped slope of Tongwei-Qin’an embankment section of Baoji-Lanzhou high-speed railway. The time history of acceleration was analyzed in both time and frequency domains, and the effects of different trains on the vibration characteristics of different terraces were studied. The results show that with the increase of the distance from the track center, the peak acceleration tends to attenuate. There is an obvious vibration rebound at the fourth terrace. The peak acceleration and vibration acceleration level of each step field are affected by train speed. However, due to the existence of vibration amplification zone, the peak acceleration of the third to fifth step field reaches its maximum when the train speed is small. Through 1/3 octave frequency analysis, the vibration amplification region mainly amplifies the components of the central frequency from 1 Hz to 10 Hz. A model of subgrade-foundation-stepped slope is established to study the influence of the change of elastic modulus of soil on vibration. It is found that coupling action of train load and gravity, the maximum displacement and Mises stress at the edge of each terrace field increase greatly. And the change of elastic modulus of soil has obvious influence on the vibration of stepped fields, while the change of elastic modulus of soil in stepped fields only affects the vibration of the stepped fields and the two adjacent stepped fields. It has no effect on the vibration far away from the terrace.更多还原