下穿飞机跑道地铁区间隧道附加荷载计算方法

为更加准确方便地计算飞机滑行过程中对下穿飞机跑道的地铁区间隧道最不利作用位置的附加荷载值，将飞机22个轮子的最不利滑动荷载峰值作为飞机静荷载作用集中力，运用布辛奈斯克理论公式求解22个轮载作用下的地层附加应力值，分析不同埋深条件下最大竖向附加应力的分布规律和量值变化规律。根据荷载-结构法与飞机附加应力的理论解，确定下穿飞机跑道地铁区间隧道附加荷载的最不利分布模式，并通过回归分析得到飞机附加应力q1、q5的简化计算公式。最后通过数值模拟的方法验证了布辛奈斯克理论公式的适用性。研究结果表明： 1）随着隧道埋深的增大，飞机最大竖向附加应力与隧道竖向围岩压力的比值先迅速下降，随后缓慢下降，当隧道埋深大于50 m时，飞机最大竖向附加应力与竖向围岩压力的比值较小； 2）不同隧道埋深下的飞机最大竖向附加应力值点位置基本一致，位于距离飞机最后一排轮子2.1~3.3 m的中轴线上； 3）飞机附加荷载最不利分布模式为近似对称梯形分布模式，此时飞机最大竖向附加应力值点位于隧道拱顶正上方； 4）简化后的附加应力q1与隧道埋深z呈负相关关系，q5与隧道埋深z、隧道洞径D呈负相关关系。

Calculation Method of Additional Load of Metro Tunnel Crossing underneath Existing Airstrip

In order to more accurately and conveniently calculate the additional load value of the most unfavorable action position of the tunnel undercrossing the airstrip during taxiing, the peak value of the most unfavorable sliding load of the 22 wheels of the aircraft is taken as the concentrated force of the static load of the aircraft. The additional stress value of the stratum under wheel load is analyzed, and the distribution and magnitude of the maximum additional stress under different depths are analyzed. According to the load structure method and the theoretical solution of the additional stress of the aircraft, the most unfavorable distribution mode of the additional load in the tunnel under the airstrip and metro is determined, and the simplified calculation formula of the additional load of the aircraft q1 and q2 are obtained through regression analysis. Finally, the applicability of the J. Boussinesq theoretical formula is verified by numerical simulation. The research results show that: (1) As the burial depth of the tunnel increase, the proportion of the maximum vertical additional stress of the aircraft to the surrounding rock pressure of the tunnel decreases rapidly first and then slowly; when the burial depth is greater than 50 m, the proportion of the maximum vertical additional stress of the aircraft is relatively small. (2) The positions of the maximum vertical additional stress value of the aircraft under different burial depths are basically the same, which are located on the central axis 2.1~3.3 m from the last row of wheels of the aircraft. (3) The most unfavorable distribution mode of the aircraft additional load is approximately symmetrical trapezoid distribution mode, and the point of the maximum vertical additional stress value of the aircraft is directly above the tunnel crown. (4) The simplified additional stress q1 is negatively related to the burial depth z of the tunnel, and q5 is negatively related to the burial depth z of the tunnel and the tunnel diameter D.