摘要
随着铁路工程的高速发展,越来越多的基坑工程需要在高速铁路旁边进行,控制和预测列车动荷载对基坑及周围建筑的变形成为铁路工程设计中的一个重要内容,因此,列车动荷载对基坑及地基变形的影响已经引起越来越多专家和工程师的关注,对列车荷载进行研究就显得尤为重要。
在火车站附近进行基坑开挖,由于列车车辆的高密度运行,一方面,在换乘车站深基坑开挖过程中,列车动荷载会影响既有车站结构及其周围土层变形;另一方面,既有车站结构受新建换乘车站基坑开挖的影响产生变形,从而引起车站内轨道变形,影响行车安全。
对于列车动荷载的模拟,在以往的基坑支护中很少考虑,只是在道路工程中把列车荷载当做等效的静荷载进行计算。本文以某大型车站基坑开挖过程中实际监测数据为例,通过FLAC3D模拟基坑在列车运行期间的开挖变形,并将模拟结果与实际监测的数据作对比,计算结果表明:根据实际监测数据,列车动荷载引起的地基沉降会随着时间一直增大,但增大的速率越来越小,最终趋于稳定;由于锚索与测斜管在有无列车通过时无变化,说明列车动荷载只对其作用周围某一范围内的土体有影响。因此,为了减小列车动荷载对基坑及土体的影响,可只对列车影响临界范围内的土体进行加固,从而以最经济的工程成本来达到预定的设计目的。
With the rapid development of railway engineering, more and more foundation engineering need to be constructed beside the railway, controlling and predicting the deformation of the foundation engineering and surrounding buildings that caused by the dynamic train load become an important content of the railway engineering design. So the deformation of the foundation engineering and ground that caused by dynamic train load have attracted more and more experts and engineers to research. So studying on train load is becoming very important.
When the excavation near the train station, because of the high density of train vehicle running, on one hand, in the process of excavation in the subway station, the dynamic train load affects the structure of existing station and the deformation of the surrounding soil; on the other hand, deformation will be caused because of the excavation during the existing station structure, Causing the deformation of the station track, and impacting the safety of the traffic.
The simulation of the train dynamic load is rarely considered in the past foundation design. The train load is calculated as equivalent static load only in the road engineering. The article takes the data of the excavation during a certain station as an example, using the FLAC3D to simulate the deformation of the excavation during the train operation and making a comparison between the simulation results and the actual monitoring data. The calculation results show that according to the actual monitoring data, the ground settlement caused by the dynamic train load has been increasing as time goes by, but the rate of the growth is becoming more and more small, eventually stabilized. Because no matter there is a train or not, the reading of the anchor cable and inclinometer tube doesn‘t change, this illustrates that the dynamic train load only affects the soil in a particular range. Therefore, in order to reduce the dynamic train load on foundation pit and soil, we can reinforce the soil that only affected by the train so that using the least cost to achieve the design purpose.
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