Abstract Based on the hydrological conditions of the observation points, topography, lithology and structural features of the Shangjiawan tunnel, it was determined that large karst caves may be encountered during construction, which could result in geological hazards such as water inflow and mud bursts. Based on an early risk assessment, a comprehensive geological prediction method is adopted in this paper to explore the unfavorable geologic bodies in front of the tunnel, utilizing the seismic prediction (TSP) method for the karst cave at ZK67+835, the ground penetrating radar (GPR) method for the cave at YK67+805 and advance drilling for the specific location, strike and dimensions of the cave under the tunnel floor. The results show that the karst caves in the left and right tunnel tubes are interconnected with each other, forming an extra-large underlying unfilled cave. Aimed at the characteristics of the disclosed caves, such measures as filling and bridging are used for this project; backfilling is appropriate for the left tunnel tube, which has no water passing through during the rainy season, and bridging is appropriate for the right tunnel tube, with the structural load borne by a simple beam and the vehicle load by a cover plate. This treatment scheme is verified by rock deformation monitoring after treatment.
Abstract：
Based on the hydrological conditions of the observation points, topography, lithology and structural features of the Shangjiawan tunnel, it was determined that large karst caves may be encountered during construction, which could result in geological hazards such as water inflow and mud bursts. Based on an early risk assessment, a comprehensive geological prediction method is adopted in this paper to explore the unfavorable geologic bodies in front of the tunnel, utilizing the seismic prediction (TSP) method for the karst cave at ZK67+835, the ground penetrating radar (GPR) method for the cave at YK67+805 and advance drilling for the specific location, strike and dimensions of the cave under the tunnel floor. The results show that the karst caves in the left and right tunnel tubes are interconnected with each other, forming an extra-large underlying unfilled cave. Aimed at the characteristics of the disclosed caves, such measures as filling and bridging are used for this project; backfilling is appropriate for the left tunnel tube, which has no water passing through during the rainy season, and bridging is appropriate for the right tunnel tube, with the structural load borne by a simple beam and the vehicle load by a cover plate. This treatment scheme is verified by rock deformation monitoring after treatment.
.Comprehensive Geological Prediction and a Relevant Treatment Scheme for a Large Karst Cave in Tunnel Construction[J] MODERN TUNNELLING TECHNOLOGY, 2015,V52(2): 192-197
2015, Vol. 52 