Study on the anti-floating water level of the underground structure's comprehensive anti-floating

Abstract

A significant amount of groundwater is in the underground rock and soil, which can exert buoyancy force on the underground structure. In severe cases, this can result in damage, such as cracking of basement walls and arching of floors. Single-using passive anti-floating measures cannot actively reduce the water load of the underground structure when a sudden high water level occurs. Single-using active anti-floating measures may cause environmental problems, and the reliability and durability of the system are difficult to guarantee. This paper adopted the comprehensive anti-floating method of active and passive combination, and the water level distribution function was established based on the measured data of the groundwater depth. The relationship between the normal water level (NWL) and the failure probability of passive anti-floating, which is the starting probability of active anti-floating (SPAA), was obtained. Then, according to the soil properties of the substrate where the active anti-floating system was located, the design service life of the building, the building function, and how the active anti-floating system affected the surrounding environment, assess the harm caused by exceeding the NWL, select the appropriate SPAA, and determine the NWL, which is the anti-floating water level (AWL) of passive anti-floating. Conventional passive anti-floating measures control groundwater below the NWL. When the water level exceeds the NWL, active anti-floating measures of active pressure relief are adopted. Whether groundwater rises or falls, it will not cause structural anti-floating failure. Reasonably selecting the anti-floating program and AWL ensure the underground structure's anti-floating effect to achieve a balance between its safety and economic viability. The new method was theoretically analyzed using measured one-year groundwater depth data from an observation well in Beijing's Fangshan District.