梁的约束对液化场地桥台震害模式的影响分析
Impact of Beam Restriction on Seismic Damage Modeof Abutments in Liquefied Ground

为深入研究液化场地梁的约束对桥台震害模式的影响，首先在对唐山地震中胜利桥震害调查的基础上，采用有限元软件UWLC对该桥震害进行数值模拟分析，并将数值模拟结果与实际震害结果进行对比验证。研究结果表明：数值模拟结果与实际震害结果基本一致，说明采用UWLC软件进行震害数值模拟分析是可行的。然后对有、桩基条件下梁的约束力和液化层厚度对桥台震害模式的影响分别进行数值模拟分析。研究结果表明：在地震作用下，桥梁发生落梁破坏后会导致桥台的滑移破坏更为严重。与桩基的重力式桥台不同，桩基桥台的震害模式均表现为前倾式破坏，这主要是因为桩基础限制了桥台底部的水平移动。梁的约束力对桩基桥台震后残余位移的影响程度要明显小于桩基桥台。对于重力式桥台，液化砂层对地震波的中高频段有一定滤波作用，反映出液化层的减震作用；而对于桩基桥台，由于桩-土-台身的相互作用，液化砂层的减震效果不明显。
As a key connection structure in modern transportation networks, bridges are readily affected by earthquakes. Abutment failures not only cause the loss of function, but also lead to damage of entire bridge structures. To further research the influence of beam constraints on abutment damage in liquefied ground, in this paper, we investigate earthquake damage to the Shengli Bridge in the 1976 Tangshan earthquake, use UWLC software to conduct a numerical simulation analysis of the earthquake damage to the Shengli Bridge, and compare our results with the actual seismic damage. We found the numerical simulation results to be generally consistent with those of the actual seismic damage, which indicates that the UWLC finite element software has a good fitting ability. We numerically simulated the influence of the restraint force of the beam and the thickness of the liquefied layer on abutment damage modes with and without a pile foundation. The results show that under earthquake action, bridge abutment breakage is more serious. Unlike the gravity abutment with no pile foundation, we found the damage modes of abutments with a pile foundation to be forward-collapse failure, mainly because the pile foundation restricts the horizontal movement of the abutment bottom. The post-seismic displacement of abutments with a pile foundation is less affected by the restraint force of the beam than that of abutments without a pile foundation. For the gravity abutment, the liquefied sand layer has a certain filtering effect on the middle and high seismic-wave frequency bands, which reflects the damping effect of the liquefied layer. For pile-foundation abutments, the damping effect is not obvious due to the pile-soil-platform interaction.