Calculation on water inflow of large underground water-sealed storage during operation and grouting design

Prediction of water inflow in caverns has been a big problem for a long time, and the predication during construction has not been effectively combined with the water sealing by grouting, resulting in excessive grouting cost and difficulty in acceptance of storages during construction, which have caused great problems to the design, construction and operation of underground storages. Herein, a seepage field model was firstly established by FEFLOW software based on the actual geological conditions and the layout of underground works of a underground water-sealed storage, the water inflow of the storage during its operation without water-sealing by grouting was calculated by simulation, and the recommended water inflow value was finally determined to be 10 115 m³/d through the mutual verification with the calculation results of the empirical formula. Further, the permeability coefficient was calculated according to the requirements of relevant specifications. Definitely, the average permeability coefficient of the whole storage area needed to be reduced from 1.1×10^-5 cm/s to 1.09×10^-6 cm/s, which could guide the grouting design in a targeted way. The calculation of water inflow and seepage control were correlated in the research for the first time, capable of accurately estimating the quantity of pre-grouting and guiding the construction organization design, thus effectively overcoming the common difficulty in acceptance and commissioning of similar projects due to excessive water inflow.