铁路隧道整体道床的沉降与基底状况关系的分析

为查清铁路隧道整体道床破损的原因,研究在列车作用下道床的沉降与基底状况的关系,根据焦柳线银匠界隧道整体道床实际情况建立力学计算模型。采用弹塑性有限元法进行计算,绘出在不同的基底状况下地基弹性模量与铁路隧道整体道床沉降的关系曲线。计算得到的沉降值与实际测得的数据吻合。研究表明:道床的沉降和道床下软基被淘空的情况有关,以道床下软基两端逐步向中间被淘空为最不利情况。道床的沉降和基底的弹性模量成非线性关系,在基底弹性模量不断减少的一个较大的范围内,整体道床的沉降比较均匀,而当地基弹性模量降至30 MPa以下时,整体道床的沉降将急剧加大。利用所绘制的关系曲线,并根据查明的道床基底地质情况可预报该区域的沉降,或根据道床的沉降估计道床的基底情况。通过计算还发现,在基岩、侧沟、边墙、人行道和围岩对整体道床的作用中,围岩的作用有限。

Analysis of the Relationship between Subsidence of Monolithic Roadbed of Railway Tunnel and the Situation of Foundation Base

In order to investigate the reason of dilapidation of railway tunnel monolithic roadbed and analyze the relationship of roadbed subsidence and foundation base condition affected by train,the paper established the mechanical calculation model and used the elastic-plastic finite element method to get the relation curve of elastic modulus of foundation and the subsidence of railway tunnel monolithic roadbed under different situation of foundation base according to the actual situation of monolithic roadbed of Yinjiangjie tunnel on Jiaoliu line.The subsidence value calculated in the paper agreed well with the test data.The analysis results indicated that the subsidence of roadbed was affected by the situation of the weak foundation base under roadbed which was hollowed out,and got worst in the case of the flexible foundation dredged generally from its two sides to the middle part.The relationship between the subsidence of roadbed and the elastic modulus of foundation was non-linear and the change of the subsidence of roadbed was regular when the elastic modulus of foundation was reduced incessantly among a wide range.However,the subsidence of monolithic roadbed increased sharply when the elastic modulus of foundation dropped below 30MPa.Utilizing the relation curve demonstrated in the paper,the subsidence of the district could be predicted by the discovered geological situation of roadbed foundation.Besides,the situation of roadbed foundation could be estimated by the token of the subsidence of roadbed.The analysis of the interaction of the bedrock,the side channel,the side wall,the sidewalk and the surrounding rock proved that the effect of surrounding rock was limited.