复杂地形条件下桥上CRTS Ⅱ型轨道系统地震响应
Seismic responses of CRTS Ⅱ track system on bridge under complex geography conditions

为了研究复杂地形对桥上CRTS Ⅱ型轨道系统地震响应的影响,以沪昆高速铁路线16～32 m简支梁桥为例,考虑钢轨、扣件、轨道板、砂浆层、底座板、滑动层、桥梁、固结机构、端刺与挡块等部件,建立了多跨简支梁桥-双线CRTS Ⅱ型轨道系统非线性动力学仿真模型,研究了桥上CRTS Ⅱ型轨道系统纵向力分布特征; 设置了4种典型地形工况,分析了不同墩高条件下桥上CRTS Ⅱ型轨道系统地震响应规律。分析结果表明:与非纵连轨道结构相比,桥上CRTS Ⅱ型轨道结构最大钢轨应力相对较小,约为138.8 MPa,应力包络曲线呈反对称,线形平滑; 轨道板和底座板共同承受纵向力,其最大值均出现在桥台附近,最大拉应力分别达到25.2、27.1 MPa,将在地震中发生开裂; 在地震中,端刺承受着巨大的纵向力,可达14～20 MN; 底座板与桥面之间相对位移超过24 mm,对系统有隔震耗能作用; 地形对钢轨、轨道板和底座板纵向力的影响约为30%左右,对墩底剪力影响较大,在地形发生突变处,墩底剪力增幅达4倍; 靠近桥台处的滑动层横向变形较大,可达2.7 mm,随着墩高增大,扣件与滑动层纵横竖变形增大; 在地震作用下,滑动层普遍存在着较大的竖向变形,桥台附近滑动层竖向变形可达43.5 mm; 在地震中,挡块与底座板之间存在着频繁的碰撞现象,桥台附近挡块碰撞力可达38 MPa,挡块将发生损坏。
To study the effect of complex geographies on the seismic responses of CRTS II track system on bridge, the 16-32 m simply supported bridge on the Shanghai-Kunming High-Speed Railway was taken as an example, the nonlinear dynamics simulation model of multispan simply supported bridge and double CRTS Ⅱ track system was established based on considering rail, fastener, track plate, mortar layer, base plate, sliding layer, bridge, consolidation mechanism, terminal spine, check block and other parts, and the longitudinal force distribution characteristics of CRTS II track system on the bridge were studied. Four kinds of typical geography conditions were set to study the seismic response rules of CRTS Ⅱ track system on the bridge. Research result shows that compared with the non-longitudinal continuous track structures, the maximum track stress of CRTS Ⅱ track structure on the bridge is relatively smaller and about 138.8 MPa, and its stress envelope curve is antisymmetric and more smooth. Track plate and base plate together bear longitudinal forces, and their maximum values are near the bridge abutment and are 25.2 MPa and 27.1 MPa, respectively, which can result in cracking during the earthquake. The terminal spine bears huge longitudinal force that can reach 14-20 MN. During earthquake, a greatly relative displacement more than 24 mm occurs between base plate and bridge deck, which has the effect of seismic isolation and energy consumption. The geography conditions have 30% influence on the longitudinal stresses of rail, track plate and base plate, while have greater influence on the shear force at the pier bottom. The shear force at the pier bottom increases 4 times where the terrain(pier height)mutates. The lateral deformation of sliding layer near the abutment is larger and can reach to 2.7 mm. With the increase of pier height, the longitudinal, lateral and vertical deformations of fastener and sliding layerincrease. The sliding layer generally has larger vertical