微型桩加固土质边坡的加速度响应及其频谱特性研究

通过大型振动台试验,对微型桩及桩间土的加速度峰值分布规律进行了分析,并利用小波包分析具有的频带划分均匀能力和时频局部化性质,对水平向加载的El-centro波进行了分解,从而对其频谱特性进行了研究。试验结果表明:(1)由于加速度沿高程放大效应的影响,微型桩及桩间土的加速度峰值往往在桩顶处达到最大值;(2)影响微型桩和桩间土加速度的主要频段为低频地震波即第一频带(0.10~6.26 Hz)及第二频带(6.26~12.51 Hz);(3)高频地震波作用下,滑体底部位置处桩间土的响应情况较微型桩来说更加强烈,而在桩底位置处后排微型桩的加速度响应更为强烈。在实际工程设计与施工中,应避免微型桩与第一频带及第二频带下的地震波发生共振,对加速度响应比较强烈的位置应重点关注。研究结果可以为同类地区治理类似滑坡提供抗震设计支撑。

Study on Acceleration Response and Spectrum Characteristics of Soil Slope Reinforced by Micro-pile

Based on large scale shaking table test,the acceleration peak distribution rule of the micro-pile and soil between piles was analyzed.The El-centro wave loaded horizontally was decomposed by using the frequency band dividing uniformity ability and time-frequency localization property of wavelet packetanalysis,in order to study the frequency spectrum characteristics of El-centro wave.The results show that:(1)Because of the magnification effect of acceleration along the elevation,the peak acceleration of micro-piles and soil between piles often reaches the maximum value at the top of piles.(2)The main frequency bands affecting the acceleration of micro-piles and soil between piles are low-frequency seismic waves,i.e.the first frequency band(0.10~6.26 Hz)and the second frequency band(6.26~12.51 Hz).(3)Under the action of high-frequency seismic wave,the response of soil between piles at the bottom of sliding body is higher than that of micro-piles,and the acceleration response of back-row micro-piles at the bottom of pile is higher.In practical engineering design and construction,the resonance between micro-piles and seismic waves in the first and second frequency bands should be avoided,and more attention should be paid to the location of strong acceleration response.The research results can provide seismic design support for similar landslides in similar areas.