Effects of inertia force on the dynamic behavior of Sand

为研究振动对路基反力的影响，在干砂层中横向拉拔埋管。研究发现，当且仅当横向震动时，路基反力减小。这种力减少的程度很大程度上取决于震动的强度，而埋置、砂密度和频率的影响较小。进一步的研究是在饱和水的地面上进行的，其中土壤在震动过程中会发生液化。研究发现，动管周围的胀气增大了路基反力。然而，当振动仍在进行时，剪胀机制被破坏。上述观察的原因似乎是由于循环应力的施加造成了颗粒接触的损失。

A buried pipe was pulled laterally in a dry sand deposit in order to study the effects of shaking on the subgrade reaction force. It was found that the subgrade reaction decreases when and only when the ground was shaken laterally. The extent of this force reduction was strongly dependent on the intensity of shaking, whilst minor effects of embedment, sand density, and frequency were detected. Further studies were made by using water-saturated ground in which soil liquefaction occurred during shaking. It was found that dilatancy around the moving pipe increased the subgrade reaction. However, the mechanism of dilatancy was destroyed when shaking was still on-going. The cause of the observation stated above seems to be the loss of grain contact due to the cyclic stress application.