High-pier bridges generally refer to bridges with relatively high piers, whose pier height is often much higher than that of ordinary bridges. Such bridges are commonly used in highway projects in mountainous areas and transportation projects spanning deep valleys or rivers. In regions with large terrain undulations and complex geological conditions, high-pier bridges can skillfully utilize the terrain, reduce mountain excavation, protect the ecological environment, while ensuring the smoothness of roads and improving driving comfort and safety. However, the construction of high-pier bridges is not an easy task. It faces numerous technical challenges and difficulties, imposing extremely high requirements on construction technologies and processes.

1 Technical Characteristics of High-Pier Bridges

1.1 High Construction Difficulty and Long Cycle

Most high-pier bridge projects need to be completed at heights, thus posing significant safety risks. External factors such as weather and geology are likely to affect project construction, greatly increasing safety risks and difficulties during the construction process, and resulting in a relatively long construction cycle. Compared with other ordinary transportation projects, high-pier construction technology features a longer construction cycle and higher construction difficulty. To ensure the safety and quality of high-pier bridge construction, enterprises need to invest more material resources, manpower, and funds to ensure the safe and smooth completion of construction operations, which also leads to an increase in project construction costs.

1.2 High Quality Requirements

Quality has always been the focus of attention of various units and all sectors of society in transportation engineering construction. In the past, it is not difficult to find incidents such as pier column fractures caused by substandard quality, resulting in serious losses of life and property, as well as significant adverse social impacts. In road and bridge projects, high-pier construction technology is a common construction method. The overall durability and safety of the bridge are largely affected by the quality of high-pier construction. If there is a quality non-compliance problem at a certain node or detail, it will pose potential quality and safety hazards for the high-pier structure. In the later stage, affected by factors such as earthquakes and external loads, serious accidents are likely to occur.

2 Application of High-Pier Construction Technology

2.1 Formwork Construction

Relevant personnel need to attach great importance to the quality of materials used in pier construction to ensure the construction effect of high-pier bridges. During the work, staff can adopt steel formwork assembly, clarify the assembly method to ensure the overall stability of pier construction, reduce the difficulty of formwork removal in the later stage, and improve the tightness of joints. In addition, before the official start of construction, staff need to accurately measure the formwork size, strictly control formwork errors, and ensure that all parameters and errors are within the scope of standard requirements to avoid quality and safety accidents caused by large dimensional errors in the later stage. At the same time, before concrete pouring, staff need to strictly inspect the installation position of the steel formwork, control the pouring time, speed, and vibration work to ensure that the formwork can withstand the pressure from the internal concrete, thereby improving the level of construction quality and safety.

2.2 Surveying and Staking

The construction of high-pier bridges must carry out preliminary surveying and staking in strict accordance with construction standards to ensure that accurate and standard data can be used as parameters for subsequent construction operations. If the staking is not precise in the preliminary preparation stage, it may lead to the inability to carry out subsequent work or even safety accidents. During construction, if staff find unreasonable aspects in the preparation work, they should communicate and adjust in a timely manner to ensure construction quality and quantity. For this reason, in the surveying and staking stage, staff must conduct rigorous measurements and re-surveys of data at different positions such as the front, back, left, and right of the high pier, and strictly control errors. The surveying and staking  stage has high requirements for the proficiency and technicality of operators, so professional surveying and staking personnel are generally required to complete the operations at this stage. In addition, staff must carefully and meticulously record all surveying and staking data, and comprehensively check the accuracy of the data. If any unreasonable values are found, re-measurement and confirmation should be carried out to provide data accuracy and strongly support the smooth development of subsequent work. Managers should organize personnel to clean the site before surveying and staking to facilitate the survey work. All construction personnel must understand that the accuracy of surveying helps guide the development of the next step of work and ensures the quality and safety of project construction, so they need to fully cooperate with the surveying and staking work.

2.3 Scaffolding Erection

Scaffolding should be used in strict accordance with construction operation standards, and the correctness of scaffolding operation and quality should be ensured during transportation and use. Scaffolding with problems such as deformation shall not be used in high-pier bridge construction to avoid large construction errors or even safety accidents caused by substandard scaffolding quality, prevent unqualified scaffolding from damaging construction tools, and ensure the smooth development of subsequent work. Before the official use of scaffolding, staff need to strictly inspect the overall condition of the scaffolding, formulate a reasonable scaffolding erection plan, install and erect the scaffolding in strict accordance with safety and strength standards, and strictly control the installation of horizontal, vertical, and diagonal connecting rods in accordance with the overall scaffolding erection requirements. Managers should attach great importance to scaffolding design and installation operations, scientifically predict and reasonably adjust the settlement value, attach importance to preparation work, and organize personnel to clean up garbage and foundation soil in advance to ensure the overall stability of scaffolding installation. Afterwards, calculate and verify the mechanical properties of the scaffolding structure, analyze the force situation of key links, and ensure that the stiffness and hardness of the scaffolding can be controlled in strict accordance with construction requirements. 2.4 Steel Bar Engineering

To ensure the normal development of construction operations, the scaffolding in high-pier construction needs to be firmly installed. Only after ensuring the stability of the support can the steel bar construction operations be carried out. High-pier bridges have a high height, so it is quite difficult to ensure overall stability, and most of the support parts bear external forces through steel bars. Therefore, it is necessary to strictly control the construction quality of the steel bar engineering during the construction process. Firstly, the high-pier support structure should be reasonably designed, and the specifications and quantity of steel bars used should be clarified. Secondly, purchase the quantity and specifications of steel bars accurately according to the design results, process the steel bars precisely, control waste problems, and ensure that the construction can be carried out smoothly in accordance with the established construction technology. In steel bar engineering, welding is a key point of quality control. To ensure seamless welding and improve welding quality, professional personnel should be selected for operation to ensure that the steel bar structure is firm and stable, and can truly play a supporting role in the later stage.

2.5 Concrete Pouring

The bearing capacity and apparent quality of high-pier construction directly depend on the quality of concrete pouring, and the concrete structure is also a crucial part. Before the official start of concrete construction, special managers should monitor the construction quality, strictly supervise the concrete batching and mixing operations, and improve the quality of raw materials. Strictly control the concrete mix ratio according to the actual needs of the project, and check whether its quality meets the specification requirements after mixing. Segregation is a common problem in the preliminary mixing and transportation of concrete. Special personnel need to check for segregation quality problems, record the actual situation, and report it to the project department in a timely manner to ensure the overall quality of concrete construction. Due to the high operation height of high-pier bridges, the layered pouring method can be adopted in construction. It is necessary to pay attention to controlling the gap between different layers of concrete to ensure seamless connection, and professional technical personnel should monitor the site to ensure that it meets the pouring requirements. If construction has to be suspended due to adverse factors, the construction interval should be properly reserved to avoid seriously affecting the pouring quality.

Conclusion

In bridge engineering, high-pier construction technology occupies a very important position, affecting the service quality, safety, and service life of the bridge. Affected by the technical level of construction personnel and the level of project management, high-pier construction technology is prone to safety risks. For this reason, staff need to consider many issues, attach importance to each construction link, ensure the safe and smooth completion of construction operations, and comprehensively improve the level of construction quality and safety.