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Tunnel excavation tends to be affected by karst cavities in karst areas. Some cavities that are at low risk of causing safety issues without treatment tend to be ignored in the design and construction of tunnels to reduce costs. It is necessary to gain a better understanding of the effect of such a cavity on the seepage around a tunnel, the deformation of the surrounding rock, and the stress of the tunnel lining. In this paper, a two-dimensional rock-tunnel hydromechanical model with a karst cave was established with FLAC3D finite difference software to simulate the tunnel excavation with the consideration of seepage. Numerical simulations were performed to analyze the deformation of the surrounding rock, the seepage field of the surrounding rock, and the stress of the tunnel lining, and the results were compared for scenarios when the karst cave is at different locations relative to the tunnel. These results can provide a reference for the design and construction of tunnel engineering in rock with karst caves.

Freezing damage is one of the main diseases of tunnels in cold regions. Water storage behind the lining is a necessary condition for freezing damage. Compared with the previous condition of uniform water storage behind the lining, this paper explores the influence of water storage and frost heave at different positions on tunnel structure in cold regions. Based on the theory of thermo-hydro-mechan?ical coupling. The finite element model of tunnel surrounding rock in cold area under different positions and different water content is established and compared by using COMSOL software, the mechanical characteristics of tunnel lining under different water storage positions behind the lining are studied, and the influence of frost heave at different positions on tunnel structure is explored. The numerical simulation results show that no matter where the local water storage area is lo?cated, the area with the largest frost heave force is located in the lining structure, close to the surrounding rock. Different local water storage positions will also have different influences on the tunnel structure. In the same water storage area, the frost heave force will increase with the decrease of temperature.

There are very few living examples of engineering test cases in domestic aquifer underground gas storage construction, however, engineering test analysis can greatly reduce the risk of evaluation. This paper systematically introduced interference well test method application of aquifer gas storage construction in Huabei oilfield, and take the target of the D5 aquifer construction in Jizhong depression as an example to analyze the reasonable water injection, excited period and interference test results. Interference well test result shows that the target cap rock of D5 aquifer is sealed, the fault vertical sealing ability is good, the sealing condition of the reservoir is provided, and also the horizontal connectivity of the reservoir is good. The research results are directive and with reference value for the construction of aquifer underground gas storage in China. 1