铁路路堑型明洞顶部垂直土压力的研究

由于受到地形限制或平山造地政策的影响,浅埋明洞回填深度可能较大。而规范中的土柱法仅适用于回填高度较低的情况且并未对回填土高度做出明确规定,所以简单使用土柱法已经不能满足工程安全与经济的要求。为明确明洞回填土荷载,基于Marston理论考虑明洞拱部上方内外土柱变形差异以及偏压回填情况,建立路堑型明洞拱顶垂直土压力计算模型和计算公式,给出不同埋深土压力系数的取值,理论计算与有限元结果相吻合。研究结果表明:路堑型明洞拱顶垂直土压力变化趋势为先增大后减小;埋深大于10 m时,路堑对称型明洞拱部垂直土压力的分布规律不再随埋深改变而发生变化;路堑偏压型的分布规律则随埋深变化而变化,埋深增大两侧土压力分布系数差值越小。

Study on Vertical Earth Pressure on Top of the Open Cut Tunnel with Cutting Slopes

Due to the impact of terrain or land forming policy,the depth of backfill of shallow buried tunnel may be larger. The soil column method in the standard is only applicable to lower backfill height and the height of the backfill has not been clearly defined. Therefore,simply use of the soil column method can not meet the requirements of engineering safety and economy. Considering the deformation difference of the soil column above the arch and bias backfill soil,this paper establishes calculation model and formulates calculation formula of the vertical soil pressure for the open cut tunnel with cutting slopes based on Marston theory,and offers the values of soil pressure coefficients at different depths.Theoretical results consistent with the results of finite element analysis. The results show that the pressure of the open cut tunnel with cutting slopes increases at first and decreases later. When depth is greater than10 meters,vertical soil pressure distribution of the symmetric open cut tunnel is relatively stable,and the distribution law of cutting bias type varies with the change of the buried depth. The deeper the buried depth,the smaller the difference between pressure distribution coefficients of two sides