Pumping of confined water is one of the main problems faced by deep foundation pit engineering. And group well pumping test is the main method to reasonably analyze the drawdown of confined water and surface settlement around foundation pit engineering

which is of great significance. A large-scale deep foundation pit pumping test in the area of a terminal in Shanghai was selected as an example in this study. Combined with the engineering geology and hydrogeological conditions of the site

the confined water level change and surface settlement during the group well pumping tests were analyzed. The influence of the drawdown of confined water on soil layer compression and ground settlement were investigated. The results showed that within the monitoring range of 300 m

the maximum ground settlement was 104.9 mm

the maximum drawdown was 21.85 m

and the ground settlement caused by the drawdown per meter was about 5mm. The maximum compression of 7th soil layer was 68.4 mm

and the compression caused by one meter of drawdown was about 3 mm. The ratio of settlement to drawdown tended to decrease with the increase of distance

and within the range of 40−310 m from the center

the ratio of settlement to drawdown was 4.22−1.17 mm.