在某轨道减振与振动控制地下实验室10m埋深隧道内进行脉冲锤击试验,得到地表振动响应随水平距离的衰减规律,并建立“轨道-隧道-地层”耦合三维有限元数值模型,研究不同隧道埋深地表振动衰减规律。实测和数值模拟结果表明:地表20m区域内振动响应衰减较20m以外迅速;隧道埋深越浅,振源正上方地表振动越大;在地表20m范围内,隧道埋深越浅,地表加速度级衰减越迅速;地表振动加速度峰值包络线呈波浪型衰减,20~30m区域为垂向振动加速度第二峰值带;地表振动能量集中在30~100Hz频段。
Pulse hammer tests were carried out in the 10 m deep tunnel of the Beijing Jiaotong University Laboratory of Track Vibration Abatement & Control. The attenuation laws of ground vibration responses with horizontal distances were obtained. The three dimensional coupled track-tunnel-soil layers finite element models were established to study the attenuation laws of ground vibrations of tunnels of different buried depths. Measured results and numerical simulation indicate as follows: Vibration responses within the 20 m area of the ground attenuate faster than those beyond the 20 m area; the shorter the buried depth of a tunnel, the greater the ground vibrations right above the vibration source; within the 20 m area of the ground, the shorter the buried depth of a tunnel, the faster the attenuation of the ground acceleration levels; the enveloping curves of ground vibration acceleration peaks show undulating attenuation, the 20 m to 30 m area is the second peak area of vertical vibration accelerations; the ground vibration energy concentrates in the 30-100 Hz.