On October 22, 2022, the opening ceremony of the upper pressure shafts PS1 and PS2 and the opening ceremony of the whole line of the pressure shaft group of Pakistan SK Hydropower Station Project undertaken by China Energy Engineering Gezhouba Group III Co., Ltd. were held at the project site. The pressure shaft group with an overall elevation difference of 737.94m is equivalent to the height of more than 240 floors excavated vertically from the top of the mountain, breaking the world record for the 544m pressure shaft of Ecuador's Kocacodo Sinkery Hydropower Station. SK project owner, engineer and project management team witnessed this important moment together.

SK Hydropower Station on the Belt and Road

SK Hydropower Station is one of the first listed projects of the China Pakistan Economic Corridor in the lead of the the Belt and Road Initiative, and the first overseas green space investment of China Energy Construction Corporation. The power station is equipped with four impulse water turbine generator units with a unit capacity of 221MW, with a rated head of 859m. After completion, the annual power generation can reach 3.212 billion kWh, which is also the largest impulse water turbine generator unit under construction internationally.

The shaft group of the project is located between the surge shaft and the inlet ball valve of the power house unit, which is the most difficult and technically demanding key line for SK Hydropower Station. The penstock section of the shaft is a double track tunnel, and each penstock is composed of 3 shafts and 4 adits (the fourth pressure adit section includes a bifurcated penstock section). The successful completion of the positive expansion support construction is the pressure shaft PS1 and PS2 at the upper part of the main key line of the project construction. The full depth of the single shaft is 193 meters, the spacing between the central axes of the parallel double shafts is 28 meters, and the clear distance of the shaft wall excavation is about 23 meters. The shaft section is a circular section. According to the grade of surrounding rock, the excavation diameter is 4.74-5.18 meters, and the diameter after the support is formed is 4.68 meters.

Since the pilot shaft reverse pulling construction was started on June 25, 2021, it has been successfully completed, taking more than 16 months in total. The smooth connection of the upper pressure shafts PS1 and PS2 marks that seven pressure shafts (including one surge shaft and six pressure shafts) of SK project have been connected, and significant construction progress has been made in the construction of pressure shaft groups, which has laid a solid foundation for the successful completion of the installation and construction of steel lining of pressure shaft in the later period.

Construction difficulty

During the construction process, affected by the extrusion and dislocation of the fault, the rock mass in the upper pressure shaft is broken, and the stability of some surrounding rocks is poor. In the early stage of the shaft excavation, the pilot shaft mucking is used. During the construction, landslides of different sizes occur, and then continue to expand upward and around, eventually forming a large collapse of the shaft wall of the mucking shaft and blocking the pilot shaft. In the face of huge difficulties and challenges, all the staff of the Project Department worked together to prepare a construction plan for the excavation of the main shaft on the principle of "technical feasibility, safety and reliability, cost saving, and controllable progress", continuously optimize the design of expanding blasting according to geological changes, organize the establishment of a special construction team for the upper shaft, arrange technical experts to command ahead, and be responsible for analyzing and handling various difficult problems in the construction at the construction site, The forward excavation of the upper pressure shaft was completed 76 days in advance.

One can live up to the Green Mountains, and the Green Mountains will live up to the people. Only those who take action are better, and only those who work hard win. The nearly 7000 Chinese and Pakistani personnel of the project will work together, march forward bravely, and act as an actor to overcome difficulties. They will continue to implement the Several Opinions of China Energy Construction Co., Ltd. and various decisions and arrangements of the company. They will resolutely implement the main line of work of "focusing on construction, creating revenue, and increasing profits", comprehensively fight to win the goal of grid connected power generation, and contribute to "building globalization to building and upgrading globalization" with fruitful achievements.Editor/Xing Wentao