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为研究抗滑桩加固上覆堆积体——下伏基岩二元结构边坡的抗震机制,开展2组1∶50比尺的离心振动台模型试验,以对比分析下伏基岩堆积体边坡在抗滑排桩加固前后的地震响应特征与抗滑桩的桩身弯矩分布规律。试验时,输入4级加速度峰值连续增大的El Centro波,监测边坡模型坡面与坡体内的加速度响应、坡顶沉降变形以及抗滑桩上静、动弯矩的分布。试验结果显示由于抗滑桩抑制了上覆堆积体的下滑,坡顶的加速度峰值(PGA)放大系数、加速度反应谱以及竖向沉降变形均有不同程度的降低。抗滑桩一方面加固了上覆堆积滑体另一方面在坡体内产生了地震波的反射叠加效应,使得边坡水平响应加速度放大系数出现了桩前增大桩后减小的现象。下伏基岩堆积体边坡坡顶沉降与Arias烈度在抗滑排桩加固前后均具有良好的正相关线性关系。地震荷载作用过程中抗滑桩动力响应弯矩变化幅值明显大于地震作用后的静弯矩增量,且静弯矩与动弯矩变化幅值的分布均在基岩面附近达到峰值,易在基岩面附近造成抗滑桩的破坏,类似工况下抗滑桩的抗震配筋设计应充分考虑这一特点。
In order to study the anti-quake mechanism of the anti-slide piles in strengthening the overburden-underbedded rock slope, two sets of 1:50 scale centrifugal shaking table tests were carried out to compare and analyze the relationship between the underlying bedrock Seismic Response Characteristics of Slope Before and After Anti - Slide Piles Strengthening and Pile - Bending Moment Distribution of Anti - Slide Piles. During the experiment, the El Centro waves with continuously increasing 4-level accelerations were input to monitor the acceleration responses of the slope and slope, the settlement of top and the distribution of static and dynamic moments on the anti-slide piles. The experimental results show that the anti-slide piles can reduce the PGA amplification, the acceleration response spectrum and the vertical settlement deformation of the overburden due to the decline of the overlying deposit. On the one hand, the anti-slide pile reinforces the overlying buoyant body and on the other hand, the reflection superposition effect of the seismic wave is generated in the slope body, which makes the slope amplification factor of horizontal response acceleration decrease after the pile is enlarged. The settlement of the slope on the basement of underburden has a good positive correlation with the Arias intensity before and after the anti-slide piles reinforcement. The amplitude of dynamic response moment of anti-slide piles during earthquake load is obviously larger than the increment of static moment after earthquake, and the distribution of static bending moment and dynamic bending moment change peak near the bedrock surface. In the vicinity of the bedrock surface, the anti-slide pile is damaged. Under similar conditions, the anti-seismic pile reinforcement design should fully consider this feature.