Research conclusions：(1) Curtain pre-grouting to the krast cave can improve the soil, block the water, much reduce the water content of filling materials, improve the physical and mechanical performances, create the favorable conditions for excavation, and achieve the good effect of reinforcing the karst cave, so it is an effective to treat the karst cave. (2) Application of the primary support of the double-layer shotcrete support structure to the karst cave can effectively control the deformation of the surrounding rock, bear the most pressure of the surrounding rock and much reduce the loading on the secondary lining. (3) In consideration of the high seasonality of karstwater, the water level in the karst cave will much raise rapidly due to heavy water fall in the rain season, so the secondary lining of the tunnel should have excellent capacity of resisting the hig -pressure water to guarantee the safe service of the tunnel.