On October 8, with the successive completion of the dismantling of the survey platforms for Artificial Islands 1 and 2, the East and West Artificial Islands, and the steel pipe piles of the East Artificial Island temporary wharf, the offshore construction of the Hong Kong-Zhuhai-Macao Bridge Island and Tunnel Project was fully completed, bringing seven years of offshore construction to a successful conclusion. At present, the main structures of the East and West Artificial Islands of the Hong Kong-Zhuhai-Macao Bridge have entered the final critical stage; underground concealed works such as water supply and drainage pipeline installation have been fully completed, and island surface works are being advanced at full speed. Asphalt pavement paving over an area of 230,000 square meters will officially begin on October 11 and is expected to be completed by the end of November.
The island and tunnel project is the controlling project of the Hong Kong-Zhuhai-Macao Bridge, comprising two artificial islands each with an area of 100,000 square meters and a 6.7-kilometer-long undersea immersed tube tunnel. It is China's first offshore immersed tube tunnel and also the immersed tube tunnel with the greatest burial depth and the highest comprehensive technical difficulty in the world today. The key lines, such as artificial island formation, foundation trench dredging, foundation construction, immersed tube floating and installation, and final joint installation, all involve offshore construction and face a series of difficulties, including harsh offshore environments, high risks and challenges, great organizational difficulty, and long construction cycles.
In January 2011, offshore supplementary investigation and pile driving for the West Artificial Island survey platform began, officially opening the curtain on seven years of offshore construction. On May 15, amid the rumbling vibration and sinking of eight linked vibratory hammers, the first super-large steel cylinder of the West Artificial Island of the island and tunnel project was vibrated and sunk into the sea. In the following short seven months, the builders guarded against typhoons, ensured safety, battled high temperatures, and strived for high output, successively achieving records such as "three cylinders in one day" and "eight cylinders in four days." On December 7 of the same year, the vibratory sinking of the last steel cylinder of the East Artificial Island—120 steel cylinders in total—was completed, creating the engineering miracle of "island formation in the same year as construction began."
From August 14, 2011, to August 4, 2013, during nearly two years of sand compaction pile construction for the artificial islands, the builders successively completed the installation of 1.4 million cubic meters of sand compaction piles for the island wall structures and the immersed tube tunnel transition sections, setting multiple domestic records for the application of this technology. On the front of tunnel foundation trench dredging and desilting, after nearly five years, the rough and precision excavation of the immersed tube tunnel foundation trench, the excavation of the diversion dike foundation at the island-tunnel junction, and foundation trench desilting were successfully completed. On the front of tunnel foundation construction, offshore heavy equipment such as the self-developed "Zhenbo 28" rock dumping and tamping vessel and the "Jinping 1" crushed stone bedding leveling vessel were independently developed. On January 25, 2016, the rock dumping and tamping task for the immersed tube tunnel foundation was completed. After 1,423 days of arduous work, the laying of crushed stone bedding for all 33 immersed tube sections of the tunnel was successfully completed, with an elevation error of less than 4 cm, creating a world miracle with a 100% qualification rate.
From the start of floating and installation of the first immersed tube section E1 on May 2, 2013, to the completion of the final joint installation on May 2, 2017, during the four full years of immersed tube tunnel construction, records that captured the imagination were created one after another—from the "96-hour hard battle for the first immersed tube section" to the Chinese speed of "ten sections in one year," "two immersed tube sections installed consecutively within half a month," "an extreme docking deviation of 3 millimeters," and "millimeter-level deviation of the final joint." The construction task of installing 33 giant immersed tube sections and the final joint was successfully completed, creating the construction miracle of an offshore immersed tube tunnel that is "watertight without a single drop leaking."