Groundwater Flow Analysis Of Confined Aquifer Under Foundation Pit With Waterproof Curtain

Groundwater level control is a vital factor to ensure the security of the foundation engineering construction that incongruent control often threats the safety and quality of the pit. Therefore, some measures such as dewatering, setting waterproof curtain were used in order to achieve the control of groundwater effectively.Traditional calculation theory based on the homogeneous isotropic aquifer, infinite boundary conditions, and full penetrating well under ideal conditions, cannot adapt to the complex groundwater flow calculation and analysis of foundation engineering. How to analysis the groundwater flow reasonably in foundation engineering has become an urgent problem that need to be solved in the design of foundation engineering. Therefore, it is of both engineering value and theoretical significance to carry out the calculation method research of unsteady flow in the confined aquifer with waterproof curtain in the foundation pit. The main research results include:1. The model of unsteady flow in the confined aquifer was established by combining the impermeable boundaries of the enclosed waterproof curtain in the foundation pit. Semi-analytical solutions of unsteady groundwater flow for fully enclosed confined aquifer in the strip and circle type foundation pit were derived by using Fourier and Laplace integral transforms.2. The model of unsteady flow in the confined aquifer was established. By combining the impervious boundary of the suspended waterproof curtain and fixed flow boundary of the unclosed period in the confined aquifer, Semi-analytical solutions of unsteady groundwater flow for semi-closed confined aquifer in the strip and circle type foundation pit were derived by using Fourier and Laplace integral transforms.3. Using Laplace numerical inverse transformation, the calculation of unsteady groundwater flow in confined aquifer of foundation pit with waterproof curtain was solved. The methods of answer degradation and finite difference were used to verify the validity of the semi-analytical solution and dimensionless calculation formula was derived. Distribution rule of groundwater drawdown in confined aquifer of foundation pit with waterproof curtain is discussed. It was analyzed that how the factors influence groundwater drawdown, such as anisotropy of confined aquifer, insertion depth of partially penetrating well, the length of filter tube, insertion depth of waterproof curtain and so on.4. Numerical simulation was built to analyze the influence of decompression precipitation in confined aquifer of foundation with waterproof curtain on surroundings. It was compared and analyzed that how the factors influence inside and outside of the foundation pit with waterproof curtain, such as insertion depth of waterproof curtain, precipitation form of the foundation pit(no matter inside or outside), insertion depth of partially penetrating well, the length of filter tube and so on.