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特大跨度扁平洞室,断面形式为拱形,宽约60 m,高约20 m,高跨比为0.333,其力学行为需进行深入研究。利用颗粒流程序建立模型,模拟特大跨度扁平洞室开挖过程,研究了开挖施工过程中变形和受力特征,特大跨度扁平洞室模拟分析表明:(1)围岩破坏区主要集中在拱顶和拱底。(2)拱部围岩内的周向应力在隧道开挖后先升高,随着塌方破坏区域的扩大而后逐渐降低。(3)节理倾角对稳定性的影响影响比较大。(4)通过锚索支护可以保持特大跨度扁平洞室围岩稳定性。
The large-span flat caverns are arch-shaped with a width of 60 m, a height of about 20 m and a high span ratio of 0.333. The mechanical behavior of the large-span flat caverns needs to be further studied. The model was established by using the particle flow program to simulate the excavation process of the large-span flat caverns. The deformation and stress characteristics during excavation were studied. The simulation analysis of the cavern with large span shows that: (1) Top and bottom. (2) The circumferential stress in the surrounding rock of the arch rises first after tunnel excavation, and then gradually decreases with the expansion of the collapsed area. (3) The effect of joint inclination on stability is relatively great. (4) The stability of the surrounding rock of the large-span flat caverns can be maintained by the anchor cable support.