Abstract
Taking the deep foundation pit excavation of a certain cable tunnel as the research object, a numerical calculation model was established based on Midas GTS NX software, validated using field measurement results, and further employed to investigate the dewatering and deformation characteristics during the excavation process. The results indicate that the hydraulic head around the foundation pit exhibits a spherical distribution, with the hydraulic head outside the pit being higher than that at the pit bottom, causing water to seep from outside to inside the pit; the diaphragm wall demonstrates excellent blocking of the hydraulic connection of groundwater. The displacement of the diaphragm wall from top to bottom follows a pattern of first increasing and then decreasing, with a maximum horizontal displacement of 8.54 mm. The embedment depth of the support structure decreases with excavation depth, the maximum surface settlement gradually moves closer to the foundation pit, and the pit heave reaches a maximum value of 6 cm at an excavation depth of 22.8 m.
Full Text
Dewatering and Deformation Characteristics of Deep Foundation Pit Excavation for a Cable Tunnel
Guo Hui
China Railway 16th Bureau Group Road & Bridge Engineering Co., Ltd., Beijing 101500
School of Civil Engineering, Central South University, Beijing 101500
Abstract
This study investigates the deep foundation pit excavation of a cable tunnel, establishing a numerical calculation model using Midas GTS NX software. The model was validated against field measurement results, and the dewatering and deformation characteristics during excavation were systematically examined. Results indicate that the hydraulic head around the foundation pit exhibits a spherical distribution, with higher hydraulic head outside the pit than at its bottom, causing groundwater to seep inward. The diaphragm wall effectively blocks hydraulic connectivity of groundwater. Displacement of the diaphragm wall increases from top to middle before decreasing toward the bottom, with a maximum horizontal displacement of 8.54 mm. As excavation depth increases, the embedment depth of the support structure decreases, the location of maximum surface settlement gradually shifts toward the pit, and pit heave reaches a maximum value of 6 cm at an excavation depth of 22.8 m.
Keywords: cable tunnel; deep foundation pit; excavation process; dewatering; deformation characteristics