道岔梁支架扩大基础快速预压试验及数值模拟

Rapid Preloading Test and Numerical Simulation of Enlarging Foundation of Turnout Beam Support

为提升铁路道岔梁支架基础预压的施工效率,借鉴静压桩机施加荷载方式提出一种扩大基础预压工法,以适应场地施工条件和项目工期要求。依托马来西亚东海岸铁路道岔梁工程,设计快速和慢速维持荷载预压方案,通过有限元仿真分析荷载持续时间内的基础沉降变化规律,并结合现场试验验证所提施工方案的合理性。结果表明:扩大基础复压后沉降趋势由陡变缓,与堆载法比,两种预压方案所需的预压完成时间显著减少;同一预压荷载条件下,基础沉降均在维持最大荷载1 h后逐渐稳定,延长荷载维持时间对基础预压效果影响有限;扩大基础两端沉降量变化在施工过程中并不相同,但随着预压完成趋于一致,且平整度符合施工要求。快速维持荷载预压下的扩大基础工后实测累积沉降量不超过0.15 mm,不仅能有效缩短工期,而且预压效果比慢速维持荷载预压方案要好。

In order to improve the construction efficiency of foundation preloading of railway turnout beam supports and adapt to the construction conditions and construction period of the site,an expanded foundation preloading method based on the load applied by a static pressure pile machine was proposed.Relying on the railway turnout beam project on the east coast of Malaysia,fast and slow maintenance load pre-compression schemes were designed.The variation rule of foundation settlement within the load duration was analyzed through FEM simulation,and the reasonableness of the proposed construction scheme was verified with on-site tests.The results are as follows.The settlement trend after the repressurization of the expanded foundation changes from steep to slow.Compared with the pile load method,the preloading completion time required for both preloading schemes is significantly reduced.Under the same preloading load conditions,the foundation settlement is gradually stabilized after maintaining the maximum load for 1 h,that is,the extending the load maintenance time has limited influence on the foundation preloading effect.The settlement change at both ends of the expanded foundation is not the same during the construction process,but it tends to be consistent with the completion of preloading,and the flatness meets the construction requirements.The measured cumulative settlement of the expanded foundation under fast maintenance load pre-compression does not exceed 0.15 mm,which not only can effectively shorten the construction period,but also has a better pre-compression effect than the slow maintenance load pre-compression program.