On August 23, the Tagikamar Tunnel of the ON2 Project in Tajikistan, undertaken by Zhejiang Communications Construction Group under Zhejiang Communications Investment Group, was successfully holed through, marking that the most difficult engineering milestone of the project has finally been overcome and laying a solid foundation for the goal of opening the entire line to traffic this year.

It is reported that the Tagikamar Tunnel has a total length of 2,593 meters and is designed as a single-tube, two-lane tunnel. Its seismic resistance rating reaches Grade 9, fully taking into account the complex geological environment of frequent local earthquakes.

During construction, the geological conditions of the Tagikamar Tunnel brought unprecedented challenges to the project. Because the tunnel is located in a seismic zone, the surrounding rock has well-developed joints and fissures and is densely distributed with fault zones, and water-rich areas and weak surrounding rock occur frequently. To ensure the smooth holing-through of the tunnel, the project team carefully planned in advance and formulated a series of construction plans to address difficulties such as the harsh tunnel construction environment and poor surrounding rock geology, overcoming numerous obstacles.

In the construction of the final 150 meters of the tunnel, the project team encountered extremely complex fault zones and water-rich areas, with frequent dangerous incidents such as collapses and flowing sand. In particular, a serious collapse occurred at the tunnel inlet face, accompanied by flowing sand and roof falls, causing excavation at the face to stall for about 90 days. Faced with such a perilous construction environment, the project team promptly organized an expert team to conduct special research on collapse treatment, adopting reinforcement technical measures such as follow-up pipe grouting, I-beam arch frames and small conduits, and ultimately successfully treated the collapse within 3 months, ensuring the smooth holing-through of the tunnel.

Since the start of construction, the project team has also overcome severe natural conditions. The Tagikamar Tunnel is located at an altitude of about 1,600 meters, where winter temperatures often drop to minus ten-plus degrees Celsius, heavy snow closes the mountains and roads freeze, making material transportation extremely difficult. To ensure that tunnel construction was not interrupted, the project team prepared a winter construction plan in advance, stockpiled sufficient construction materials, and arranged equipment for road snow and ice removal to ensure material supply and construction progress. At the same time, in response to the problem of water freezing at the concrete mixing station, the project team built a self-made heating water tank and ensured the normal supply of water for concrete by heating with coal.

The holing-through of the tunnel this time is not only a milestone for the project, but also accumulated valuable construction experience under complex geological conditions in Tajikistan, providing a reliable technical reference for future tunnel construction.