Optimization of Recharge Schemes for Deep Excavation in the Confined Water-Rich Stratum

Abstract

With the excavation of a metro station in a confined water-rich stratum as our background, the sensitivity of four typical recharge parameters is analyzed by using numerical simulation. Based on the orthogonal analysis method, an optimal recharge scheme was obtained. The results show that the main influential factors of ground settlement and groundwater recovery are recharge pressure and recharge depth. The main influential factor of retaining structure deformation and influence radius of recharge is the distance between the recharge wells and the foundation pit. For the groundwater recharging of a deep excavation in the water-rich confined area of Jinan, China, the optimal effect can be achieved when setting recharge wells with a depth of 50 m arranged in a line with a spacing of 10 m at a horizontal distance of 20 m away from the retaining wall and recharge pressure is 40 kPa. With the same construction difficulty, the maximum settlement in optimized scheme decreased 71.19%, the flux of groundwater recovery increased 11.96%, the maximum horizontal displacement of the wall decreased 15.61%, and the influence radius of recharge enlarged 8.62% compared to original scheme.

Analytical Model of Tapered Thread Made by Turning from Different Machinability Workpieces

“…For the convenience of profiling and evaluation of the profiled longer and shorter flanks of the thread, two opposite-oriented axes are used: −Z and +Z (Figure 13). The points of the thread fundamental triangle are signed as in Figure 1: A, B, D, and an additional point C. The points of the thread profile that indicate its straight sections are marked by numbers: (3,4) are points of the smaller flank; (5, 6) are points of the larger flank. The half-profile angles of the tool cutting edge are the same and have the designation α 1 .…”

“…In particular, this includes exploration and extraction of hydrocarbons and geothermal and mineral resources, environmental monitoring and scientific research of the subsoil, underground archaeological excavations, infrastructure development of large cities, etc. [3]. The threaded connections of a drill string have to withstand huge axial tension, severe working torque, and extreme bending.…”