Effective evaluation of underground drainage performance in substations under episodic heavy rainfall scenarios

Abstract

[Objective] A well-developed underground drainage system is crucial for enhancing the drainage capacity of underground pipeline networks in substations under heavy rainfall scenarios and ensuring the safe operation of power facilities. [Methods] Taking a planned substation in Jieyang City, Guangdong Province, as the study area, a new underground drainage system was designed. An equivalent permeability coefficient method, coupling the “circular pipe model” and the seepage model, was proposed. A numerical model was established to evaluate the drainage performance of the underground pipe network under episodic heavy rainfall scenarios. By calibrating parameters using groundwater survey data before the construction of the substation, the drainage flow, groundwater level dynamics, and the spatiotemporal distribution characteristics of water accumulation areas under six heavy rainfall scenarios were assessed. [Results] The result showed that the new underground drainage system could effectively drain water and reduce groundwater levels around the pipeline network. After heavy rainfall, the groundwater level in the core area of the substation exhibited a trend of gradual rise and slow decline, while the surrounding groundwater levels demonstrated a pattern of rapid rise and rapid decline. Under the 50-year and 100-year return period hourly and minute-scale heavy rainfall scenarios, the new underground drainage system exhibited excellent performance, with no water accumulation. However, under daily-scale heavy rainfall scenarios of the same return periods, significant water accumulation occurred in the southwestern part of the study area, and the accumulated water from a continuous 7-day rainfall event took 4 days to recede. [Conclusion] The new underground drainage system, simulated using the equivalent permeability coefficient method under episodic heavy rainfall scenarios, demonstrates good drainage capacity, which provides an effective approach for evaluating and optimizing the drainage capacity of substation drainage networks.

Keywords

drainage network / numerical simulation / heavy rainfall scenarios / groundwater / substation / equivalent permeability coefficient method