Field Measurement Study of Hydraulic Gradient in Flood Control Area of Wuhan Area

According to “Technical Code for Building Foundation” （DB 42/242—2014）, the recommended slope of confined water head in the flood control area of Wuhan is 0.5%～0.8%, from which the anti-floating water level in the flood control area and the confined water head of foundation pit dewatering can be approximately deduced. However, since 2003, due to the substantial shortening of the supply time on both sides of the Yangtze River and the large-scale foundation pit dewatering in urban construction, the corresponding hydraulic gradient in the flood control area has also changed greatly. Combined with the water level observation and statistical data of 40 projects in the flood control area, there is a large deviation between the measured hydraulic gradient in the control area and the recommended value of the code, and there is a non-linear attenuation relationship with the water level of the Yangtze River and the distance of the project. Through data analysis, the curve equations of peak hydraulic gradient in high water period, average hydraulic gradient in high water period and average hydraulic gradient in low water period were derived and verified by the project. The conclusion can provide reference for the revision of the code, and provide support for the selection of anti-floating water level in flood control area and dewatering of foundation pit engineering.