Derivation and application of calculation formula for drawdown of pumping test in borehole

Abstract

Pumping test in borehole should be conducted before dewatering of foundation excavation of water resources and hydropower engineering. Several wells were arranged at an inverted siphon of a deep and large foundation pit. Single well pumping test and double wells pumping test were conducted and permeability coefficients were calculated. Calculation formula of drawdown in the form of a logarithmic function was derived according to drawdown of single well pumping test. Water yield calculation formula of single well pumping test was derived according to Skabaranovic formula. The calculated value is relatively close to the actual value, which indicates the effectiveness of both formulas. Calculation formula of drawdown between both pumping wells in the form of a quadratic function was derived according to drawdown of single well pumping test, which can be used to determine the minimum drawdown during double wells pumping of foundation pit. The application of all calculation formulas can be the basis for the design of dewatering scheme of foundation pit.

Keywords

deep and large foundation pit / pumping tests / water level drawdown / calculation formula / permeability coefficient / water yield