A sea-crossing bridge refers to a large bridge that spans across an ocean or bay, connecting two lands.

The construction of such bridges holds immense significance in terms of reducing land distances, facilitating transportation, and fostering economic and cultural exchanges.

These projects involve multiple professional fields, including submarine engineering, geological exploration, and bridge structure design, requiring a coordinated effort from various disciplines.

Around the world, numerous countries have undertaken the ambitious task of building sea-crossing bridges, resulting in some iconic and remarkable structures:

1. China's Hong Kong-Zhuhai-Macao Bridge stands out as the longest cross-sea bridge globally, spanning approximately 55 kilometers and linking Hong Kong, Macau, and Zhuhai. It was completed and opened to traffic in 2018.

2. Japan's Akashi Kaikyo Bridge, completed in 1995, connects Honshu Island and Awaji Island. This engineering marvel represents the world's first twin-tower suspension bridge.

3. The Golden Gate Bridge in the United States is an enduring symbol of engineering brilliance. It joins San Francisco and Marin County in California and commenced operations in 1937.

4. South Korea's Incheon Bridge, opened in 2009, connects Incheon to Yongning Island, which houses the prestigious Incheon International Airport. It proudly stands as the longest cable-stayed bridge worldwide.

These sea-crossing bridges not only showcase human engineering achievements but also play a pivotal role in driving economic growth and enhancing transportation networks in their respective regions.

However, constructing and maintaining such bridges present a series of challenges, including intricate geological conditions, environmental impacts, and susceptibility to natural disasters.

Consequently, thorough planning is imperative to ensure the safety and long-term sustainability of these grand structures.

One of the key components of a sea-crossing bridge is its piers. Piers, resembling columnar or wall-like structures, bear the weight of the bridge and its traffic loads, effectively transferring these loads to the foundation. Constructing bridge piers involves sophisticated engineering techniques and methods, and the general steps include:

1. Preliminary Preparation: Before commencing the construction of the sea-crossing bridge, meticulous survey and design work must be conducted.

This entails comprehensive geological surveys of the bridge site, determining optimal pier locations and shapes, and designing sturdy pier structures capable of withstanding expected loads and marine environmental conditions.

2. Submarine Foundation Construction: Bridge piers are typically built directly on the seabed foundation. This necessitates using methods such as caissons (watertight structures sunk to the seabed), piling (driving piles into the seabed), and dredging (removing sediments) to create a solid foundation for the subsequent pier construction.

3. Offshore Construction Platforms: To facilitate pier construction at sea, stable offshore construction platforms are established. These platforms can take the form of floating platforms, temporary supports, or even artificial islands, providing the necessary facilities and logistics for the construction process.

4. Concrete Pouring: On the offshore construction platform, formwork, and steel skeletons are used to mold the shape of the piers, and concrete is poured to fill the structure. Concrete pouring is typically done in layers to ensure optimal quality and strength.

5. Pier Structure Setup: After the concrete achieves sufficient strength, the temporary supports are removed, allowing the piers to independently support the bridge's superstructure.

6. Bridge Pier Maintenance: Following the completion of bridge pier construction, regular maintenance and inspections are crucial to preserve the structural integrity and safety of the piers.

Building piers for a sea-crossing bridge is a complex process that necessitates careful consideration of geological conditions, marine environments, construction technology, and various other factors.

Adherence to strict engineering standards and safety regulations throughout the construction process is essential to guarantee the reliability and long-term functionality of these monumental sea-crossing bridges.