隧道穿越倾斜煤层采空区段施工力学特征分析

为研究隧道穿越倾斜煤层采空区段时，采空区围岩的力学变化对隧道超前加固措施及支护结构的影响，采用Flac 3D软件模拟计算隧道穿越采空区的各施工阶段，分析采空区围岩施工力学特征的动态变化过程及隧道支护结构的受力特征。结果表明： 1）隧道在穿越上覆煤层采空区时，采用超前小导管注浆加固能有效阻止围岩的变形破坏； 2）中隔壁拆除后，初期支护结构承担了大部分围岩应力，拱腰及拱脚部位最小主应力值分别增加了13%、41.3%，改善了隧道结构的受力条件； 3）在采空区段锚杆轴力最大值为226 kN，发挥了很好的锚固作用； 4) 隧道穿越下伏煤层采空区时，采用填石注浆的加固改善比例为154.3%，治理措施较为合理。隧道二次衬砌结构的施作更是隧道安全的保障。

Mechanical Property Analysis of Constructing Tunnel Underlying Inclined Coal Mined out Area

In order to study the influence of mechanical changes of surrounding rock on coal mined areas, Flac 3D is used to simulate different phases of tunnel construction and demonstrate the mechanical variation of surrounding rocks and stress characteristics of support structures. The following results can be concluded that: (1) Grouting reinforcement with leading conduit can prevent surrounding rock deformation when the tunnel constructs underlying coal mined out area. (2) Primary support structure bears most of the surrounding rock stress after removing center diaphragms, and the minimal principle stresses at hance and arch foot section increase 13% and 41.3% respectively, which improves the stress condition of tunnel structure. (3) The bolted in mined out area can provide maximum axial force 226 kN, which anchors effectively. (4) When the coal mined out area underlies the construction tunnel, the method of rock filling and grouting helps to reduce displancement by proportion of 154.3%. Besides, the application of secondary lining structure improves the safety of tunnel construction.