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山西省汾河水库泄洪隧洞长 1140 m,跨度为 9.6～ 14.5 m。通过地层为节理裂隙极为发育的古老变质岩。施工过程中隧洞塌方 15次 ,塌方总量 2 2 6 0 m3。造成塌方的主要因素是地质结构、地下水、施工工艺。水利水电工程隧洞规定洞室上覆岩石等于地下洞室最大尺寸的 2～ 3倍 ,而该隧洞 1/3上覆岩石厚度仅为 0 .5～ 1倍洞跨 ,未造成塌方 ,个别特殊的断层地带由于采取了科学的系统化施工而未形成塌方。而一些本来能避免的塌方 ,由于未采取相应的措施而产生了大的塌方。实践证明 :在不良的工程地质条件下施工的隧洞 ,若能够采用科学的系统化施工 ,并且有效的利用由于隧洞开挖造成应力重新分布的时间效应 ,则使可能发生塌方的地段化险为夷
Shanxi Fenhe Reservoir Spillway Tunnel is 1140 m long with a span of 9.6 ~ 14.5 m. The ancient metamorphic rocks, which are extremely developed through joint formation and fissure. During the construction, the tunnel collapsed 15 times, with a total of 2260 m3 of landslides. The main factors causing landslides are geological structure, groundwater, construction technology. Water conservancy and hydropower projects tunnel provisions cave cavern is equal to the maximum size of 2 to 3 times the underground cavern, and the tunnel 1/3 overlying rock thickness of only 0.5 ~ 1 times the hole cross, did not cause landslides, some special The fault zone did not form a landslide due to the scientific and systematic construction. Some of the collapses that could have been avoided resulted in major landslides due to failure to take appropriate measures. Practice has proved that if tunnels constructed under adverse engineering geological conditions are scientifically systematized and the time effects of stress redistribution caused by tunnel excavation can be effectively utilized,