Open Cut Excavation Observational Method Associated with 3D Analysis for HKBCF PCB

The design of open cut excavations in newly reclaimed land overlying soft soils is often highly sensitive to the undrained strength parameter values. Under such circumstances, the use of the Observational Method may introduce significant programme and quantity savings by allowing the designer to adopt best estimate, rather than moderately conservative parameters. The Hong Kong Boundary Crossing Facilities (HKBCF) is located on newly reclaimed land located to the East of Chek Lap Kok Island. The Passenger Clearance Building (PCB) is located in the middle of the HKBCF and provides the customs and immigration facilities for passengers entering Hong Kong from the Hong Kong-Zhuhai-Macau Bridge and the Tuen Mun-Chek Lap Kok Link. The construction of the PCB basement required an excavation of approximately 10 m depth over an area of approximately 200 by 200 m. The typical soil profile consists of 15 m of sand fill overlying 20 m of very soft to soft Marine Clay. Ground improvement with prefabricated drains and surcharge was adopted by the reclamation Contractor to improve the Marine Clay strength.