基于能量耗散原理的振杆密实可液化地基范围研究

Reinforcement Range of Vibratory Probe Compaction for Liquefaction Site Treatment Based on the Principle of Energy Dissipation

为了建立振点间距和振动时间的计算方法,对振杆密实可液化地基加固范围进行理论预测。针对已有基于能量法的液化评估方法不适用于地基密实设计的现状,发展了基于地震容量曲线的液化评估能量方法,并对其应用于振杆密实设计的适用性进行了评价;建立了基于能量耗散原理的振杆密实模型来预测液化范围并与实测结果进行对比。研究结果表明:门槛剪应变为0.01%时预测液化范围与现场实测差别较大,基于稳定振速预测的液化范围小于基于峰值振速的预测值,达到最终液化范围的振动时间增加;门槛剪应变为0.015%时基于峰值振速预测的液化范围与现场实测差别较小,推荐使用;振动液化用时30 s左右,实际施工中无需留振;高振动频率下的能量传递效率降低,液化边界远小于共振频率下的加固范围。

The existing energy-based liquefaction evaluation methods are not suitable for the compaction design of foundations. Therefore, in this study, the reinforcement range of vibratory probe compaction for liquefaction site treatment is predicted to establish a calculation method for vibration point spacing and vibration time. In addition, a liquefaction-energy-evaluation method is developed based on the seismic capacity curve, and its applicability in the design of vibratory-probe compaction is evaluated. Next, a vibratory-probe-compaction model is established based on the energy dissipation principle to predict the liquefaction range and compare it with the measured results. The results show that the predicted liquefaction range significantly differs from that obtained through field measurements when the threshold shear strain is 0.01%. Furthermore, the liquefaction range based on stable-vibration-velocity prediction is smaller than that based on peak-vibration-velocity prediction, and the vibration time to reach the final liquefaction range is increased. As the predicted liquefaction range based on the peak vibration velocity differs only slightly from the corresponding field measurements when the threshold shear strain is 0.015%, its usage is recommended. The completion of vibration liquefaction requires approximately 30 s, and no additional amount of vibration time is required in actual construction. Moreover, the energy-transfer efficiency is reduced at a high vibration frequency, and the liquefaction boundary is much smaller than that at the resonance frequency.