Kamchik railway Tunnel of The Republic of Uzbekistan

1. Brief

The Uzbekistan Angren-Pap single-line electrified railway has a total length of 169 kilometers, which the “Kamchiq” tunnel project undertaken by our company in the form of general contracting for design and construction is the most important control project of the whole line. The length of the main tunnel is 19.2km, which is located in the Namangan Region of Uzbekistan, passing through the Kurami Mountain, through Kuinid and Sani Sarak Say River Basin.

2.Engineering Characteristics

The Uzbekistan Angren-Pap railway tunnel is a general contracting project for design and construction. The tunnel passed through the Kurami Mountain with a maximum buried depth of about 1300m. The surrounding rock is mainly granite, and there is a large additional geostatic stress. Rockburst occurs when the buried depth is less than 100m. The tunnel is a single-track railway tunnel with a small section, which is not conducive to transportation. The country is short of materials. In addition to cement and explosives, steel bars, diesel oil, waterproof and drainage materials, and detonators are all imported.

3. Key Technical Characteristics

New Austrian Method & Drilling-Blasting Method

The Kamchik Tunnel is composed of the tunnel's main tunnel and a safety tunnel. The main tunnel length is 19.2km and the service tunnel length is 19.268km. Set up 3 inclined shafts to assist the construction of the main tunnel, of which the longest inclined shaft is 3512m and the slope is 11.12%. The tunnel is designed with the new Austrian method principle and constructed by large-scale mechanized supporting drilling and blasting methods.

Rock Burst

The tunnel passes through 7 different geologic faults. During carrying out mountain blasting, the phenomenon of rock burst ejection (rock burst) often occurs. The construction is more difficult than any previous project. During the construction of the tunnel, there were more than 3000 rock bursts with only moderate strength. The most serious rock burst caused the tunnel to collapse by nearly 2000 cubic meters. In the face of ubiquitous hidden dangers, China Railway Tunnel Group organized a multinational expert meeting to conduct consultations on rock burst disasters, formulate special plans, and jointly conduct scientific research with domestic universities, formulate scientific methods to deal with rock bursts.

4. Key Technology & Innovation

The prediction of rockbursts during the construction of underground caverns is of great significance to ensure the safety of construction workers and to arrange the construction progress rationally. Therefore the "rockburst prediction method combining rock mass structure analysis and electromagnetic emission monitoring" has been innovated. The developed method,comprehensively considering the rock mass structure conditions of rockburst occurrence as well as the energy conversion and rock micro-fracture frequency during the process of rockburst,is easy to be mastered and applied by field technicians,and has proved to feasible for rockburst prediction during the construction of underground caverns.After in-depth study of the rule of rockburst and the process of rockburst, a mechanical model of the rockburst of layered rock mass is established, and the calculation formula of the critical stress of brittle failure of this type of rockburst layered rock mass is derived. Through synchronous testing, the relationship between rockburst rock sample loading-damage and electromagnetic radiation energy and pulse was obtained, and the national invention patent was obtained.

Innovate the transportation system and transportation method of the small-section extra-long tunnel, and enrich the mechanized supporting construction technology of the extra-long single-track railway tunnel. Through Jumbo, Mucking Loader, Rail Transport Corollary Equipment, Wet Shotcreting Machine, Hydraulic Self-propelled Inverted Arch Trestle, Automatic Waterproof Board Laying Trolley, Tunnel Lining Formwork, etc., establish a rapid construction line for the mechanized supporting of extra-long single-track railway tunnels, combined with the reasonable setting of auxiliary channels and excavation work surfaces, and at the same time, through the optimization of the transportation system and route layout, and simplify the set of each junction, thus successfully solved the transportation problem of the small-section extra-long tunnel. It took 900 days to complete the 19.2km main tunnel and 19.268km service tunnel excavation task, and realized the construction record of the average monthly footage of 197.5m and the highest monthly footage of 342.6m.