一种改进的隧道开挖应力释放率确定方法

为探求一种简单有效的求解隧道开挖应力释放率的方法,基于应力释放率可近似等效为位移释放率的原理,提出一种通过体积损失率求解应力释放率的方法。同时,依托于软弱围岩隧道,详述不同施工工法的应力释放率求解过程,分析各工法应力释放率的变化规律。计算结果表明:各工法的不同开挖部对应不同的应力释放率,后开挖部因受先行开挖的扰动,其应力释放率普遍大于先开挖部;除CD法外,其余工法的平均应力释放率均随施工工法的改进而逐渐变小。求解的各工法应力释放率可作为基准应力释放率,为同类隧道支护设计及施工工法优化提供一定的理论指导,具有重要的工程应用价值。

A REVISED METHOD FOR CALCULATING STRESS RELEASE RATIO IN TUNNEL EXCAVATION

To seek a simple and effective method for the calculation of the stress release ratio in tunnel excavation，a revised method was proposed via the volume loss ratio based on the principle that the stress release ratio was approximately equivalent to the release ratio of displacement. The calculation of the stress release ratios for tunnel in soft rock under different construction schemes was performed in detail and thus the variations of stress release ratios under different construction schemes were analyzed. The calculated results indicated that the stress release ratios were different for various excavation parts of different schemes. In general，the stress release ratio of latter excavated was larger than that of the part excavated earlier due to the disturbance effect of excavation. The average stress release ratio decreased gradually with the improvement of the schemes except for the CD excavation method.