高速铁路低路基桩网结构土工格栅动力特性

Geogrid dynamic characteristics of pile-net structure in low subgrade of high-speed railway

采用ABAQUS软件建立了低路基桩网结构的动力有限元模型,通过实测数据验证模型的合理性,分析了列车动荷载-土工格栅-桩-土之间的相互作用机理,研究了动荷载作用下土工格栅受力与变形规律。研究结果表明:沿线路纵向,车载作用前,桩顶土工格栅竖向变形后形状为倒"U"形,竖向变形约为2.27mm,桩顶土工格栅的拉力分布呈"M"形,桩间土工格栅的拉力分布呈倒"V"形;车载作用后,桩顶土工格栅竖向变形增量约为0.10mm,大于桩间土工格栅变形,桩顶土工格栅动位移大于桩间土工格栅动位移,桩顶边缘土工格栅拉力增量最大,桩顶中心土工格栅拉力增量较小,桩间土工格栅拉力增量最小,四桩间土工格栅拉力增量大于两桩间土工格栅拉力增量;沿路基横断面,车载作用前,路基中心土工格栅竖向变形约为12.0mm,车载作用后,格栅竖向变形的增量从路基中心至坡脚逐步减小,其竖向变形增量约为0.47mm;桩顶和桩间土工格栅动位移和动拉力整体分布规律相似,从路基中心到坡脚呈递减规律,坡脚处土工格栅动拉力为负;横断面土工格栅竖向变形增量和最大动拉力均大于线路纵向土工格栅。

The dynamic finite element model of pile-net structure in low subgrade was built by ABAQUS software, its rationality was verified with real test data, the interaction mechanism among train dynamic load, geogrid, pile and soil was analyzed, and the rules of geogrid force and deformation under dynamic load were studied. Research result shows that along the longitudinal direction of railway and before train loading, the shape of geogrid＇s vertical deformation at pile top is like upside down U, and the vertical deformation is about 2.27 mm. The distribution shape of geogrid＇s pulling stress is like M at pile top and upside down V in the soil among piles. The increment of geogrid＇s vertical deformation is about 0.10 mm at pile top under train load, and the vertical deformation is bigger than the geogrid deformation in the soil among piles. The pulling stress increment decreases gradually from the edge of pile top, the center of pile top to the soilamong piles. The pulling stress increment of geogrid is bigger in the soil among four piles than between two piles. Along the transverse direction of railway and before train loading, the vertical deformation of geogrid is about 12. 0 mm at subgrade center. Under train load, the vertical deformation of geogrid decreases gradually from the center to the slope toe of subgrade, and the increment is about 0.47 mm. At pile top and in the soil among piles, the global distribution rules of dynamic displacement and dynamic pulling stress of geogrid are similar and diminishing from the subgrade center to the slope toe. At the slope toe of subgrade, the dynamic pulling stress changes to negative value. The vertical deformation increment and the maximum dynamic pulling tress are bigger in the transverse direction of railway than in the longitudinal direction. 4 tabs, 17 figs, 33 refs.