高填明洞土压力计算方法及其影响因素研究

Calculation Method and Influencing Factors for Earth Pressure of High Fill Open-Cut Tunnel

基于岩土力学原理,考虑边坡坡角、沟槽宽度等因素,建立高填明洞的土压力计算模型,推导明洞洞顶土压力的计算公式;通过数值模拟结果和现场实测结果验证了该计算方法的正确性。依据此计算方法,进一步对影响土压力集中系数的边坡坡角、填料性质、明洞高宽比、明洞与沟槽宽度比等参数的敏感性进行分析。结果表明:等沉面高度随填土高度的增大而减小,随边坡坡角的增大而先增大后减小,随明洞高宽比、明洞与沟槽宽度比增大而增大;明洞洞顶土压力集中系数随填土高度的增加呈先增大后减小的趋势;边坡坡角增大有利于降低明洞洞顶的土压力;明洞高宽比、明洞与沟槽宽度比的增大会引起严重的明洞洞顶土压力集中现象;因此,实际工程中应在保证边坡稳定及结构安全的前提下,尽量提高边坡的坡角,减小填土沟槽的宽度,降低明洞高宽比。

Based on rock and soil mechanics principle,considering slope angle,trench width and other factors,a calculation model for the earth pressure of high fill open-cut tunnel was established and the calculation formula was derived for the earth pressure on top of open-cut tunnel.The correctness of the calculation method was validated by numerical simulation and field test results.According to the calculation method,sensitivity analysis was performed to further study parameters affecting the concentration factor of earth pressure,such as slope angle,the properties of filling material,the depth-width ratio of open-cut tunnel as well as the width ratio of open-cut tunnel and trench.Results show that the height of equal settlement section decreases with the increase of filling height;it increases first and then decreases with the increase of slope angle;it increases with the increase of the depth-width ratio of open-cut tunnel as well as the width ratio between trench and open-cut tunnel.The concentration factor of earth pressure on top of open-cut tunnel increases first and then decreases with filling height.The increase in slope angle is helpful to reduce the earth pressure on top of open-cut tunnel.The increase in the depth-width ratio of open-cut tunnel as well as the width ratio of open-cut tunnel and trench will cause serious concentration phenomenon of earth pressure on top of open-cut tunnel.Consequently,on the premise of ensuring the slope stability and structure safety in practical engineering,try to improve the slope angle,decrease the width of filling trench and reduce the depth-width ratio of open-cut tunnel.