基于统计和塑性区的隧道深浅埋划分方法研究

Research on Demarcation of Shallowly-buried and Deeply-buried Rock Tunnel Based on Mathematical Statistics and the Plastic Zone

我国现行公路、铁路隧道规范中隧道深浅埋分界深度公式是基于小跨度隧道的统计资料得出的回归公式,该公式对于跨度较大的隧道的适用性存在明显的不足。笔者通过对隧道规范建议的深浅埋分界深度与对应深度的塑性区半径进行回归分析,拟合出了两者之间的关系式;将拟合出来的关系式带入圆形隧道的塑性区理论式中,获得了隧道深浅埋划分深度的新的计算公式。将本文方法计算结果与现场实测资料和模型试验进行对比,验证本文公式的科学合理性。对比结果表明:(1)在大跨度时本文计算结果与统计结果和模型试验结果十分吻合;(2)在小跨度时本文计算结果与规范计算结果十分吻合。因此,本文方法为在围岩等级较低情况下的深浅埋分界深度计算提供了新的思路和计算方法。

The active depth calculation formula of shallow-deep buried tunnel demarcation in the normative design of railway tunnel and highway tunnel at home is based on the regression formula concluded from statistical data of the small span tunnel,which is obviously insufficient when it comes to the large span tunnel. By the regression analysis of the recommended depth of shallow-deep buried tunnel as well as the corresponding radius of plastic zone,the relationship between the two is fitted,which bring in a new depth calculation formula of shallow-deep buried tunnel demarcation when computed into the circular tunnel plastic region theory. The scientific rationality of the new formula is verified by comparing the calculation results with the field data and model test. Contrast results show：（1）the results of the new depth calculation formula are in great agreement with those of the statistics and the model test when it comes to the large span.（2） the results are in agreement with the normative calculation results in the small span. Thus the above new calculation formula may provide a fresh solution and calculation method for the depth of shallow-deep buried tunnel in the lower surrounding rock grade.