Simplified design method of pressure reduction and anti-floating for blind drain of underground structure

At present, the design of drainage blind ditches in pressure reducing and anti floating systems mainly uses numerical analysis and calculation, and there is no simple and practical simplified calculation method. Based on the assumption that the blind ditch has an equal water head boundary and the infiltration amount is uniformly distributed in the blind ditch unit, a simplified model of the drainage blind ditch grid is established. The analytical solution of the water head distribution of the blind ditch unit with a rectangular layout is obtained. The water head distribution within the blind ditch unit can be calculated by providing parameters such as the infiltration amount and the geometric size of the unit. Propose a calculation model for the distribution of bottom plate infiltration under both uniform and non-uniform infiltration conditions. Through numerical examples, it is verified that the simplified method is applicable if there is a hydrophobic layer with permeability much greater than the soil at the bottom of the blind ditch and structural bottom plate. The relative error between the simplified algorithm and the finite element results is minimal and the results tend to be conservative, which can be used for the design of blind ditch layout. Comparing typical soil layers, it was found that if the lower layer of the bottom plate is a weak permeable layer with a layer of strong permeable layer sandwiched between them, the infiltration amount of the bottom plate will be evenly distributed, and blind ditches can be evenly arranged at equal intervals; If there is no strong permeable layer in the lower strata, the infiltration amount is mostly concentrated within the range of 1 to 1.5 times the thickness of the aquifer at the bottom of the pit from the curtain. The distance between blind ditches should be reduced within this range and increased in the middle of the bottom plate.