On May 29, 2020, following the completion of beam fabrication at Wanrong Liangchang on May 25, the China-Laos Railway Project Department of the 14th Bureau of Electric Power Construction and Hydropower received good news that one of the two tunnels currently under construction, the Kaxi Tunnel, went smoothly. Through.

The Casey Tunnel has a total length of 3376 meters and was started on March 23, 2017. It lasted for 1163 days. The section of the Kashi tunnel is a structurally eroded low-middle-mountain landform with undulating terrain, with a ground elevation of 428-693 meters and a relative height difference of 265 meters. The tunnel is overlaid with Quaternary Holocene alluvial silty clay, silt, and middle sand, slope residual sedimentary silty clay, and the underlying bedrock is Triassic (T) sandstone, mudstone, shale, coal line, Suspected gas tunnel. The original design of the Casey tunnel is 550 meters for the III-level surrounding rock, 1300 meters for the IV-level surrounding rock, 1526 meters for the V-level surrounding rock, and the proportion of the IV- and V-level surrounding rock is 83.7%; The change rate is 41.88%. After the change, the grade III surrounding rock is 0 meters, the grade IV surrounding rock is 1311 meters, the grade V surrounding rock is 2065 meters, and the grade IV and V surrounding rocks account for 100%.

For more than three years, the soft rock deformation, hard rock deformation and shallow burial bias encountered in the construction of the Kashi Tunnel have been numerous, and they have encountered a "tug of war" with nature. The complex and changeable surrounding rock conditions did not scare the first-line construction personnel. "Rock changes to me". The two-step construction method and the three-step construction method are freely convertible; the exit of the Kashi tunnel belongs to the anti-slope drainage work area, and there are many water inrush , Construction personnel drainage and construction; traditional grouting and reinforcement measures have little effect. During the construction process, the palm face often digs and slips. During the construction process, "short footage, strong support" is used. In extreme surrounding rock conditions Innovatively adopting construction techniques such as closed arch in a loop and closely following the palm surface of 20 meters, effectively overcome the disadvantages of soft rock deformation and other disadvantages.

Despite the epidemic situation and the unfavorable difficulties of the surrounding rock, the Kasi tunnel passed through safely and smoothly, which laid the foundation for the beam and track laying of the China-Laos Railway, which greatly encouraged the morale of all the participants. Up to now, the only five tunnels undertaken by the China-Laos Railway Project of the 14th Hydropower Bureau are only the Ramengshan Tunnel. The project department will continue to carefully organize and make persistent efforts under the premise of doing a good job in epidemic prevention to ensure the safe and orderly progress of the remaining projects and achieve the ultimate goal of safe and smooth completion.

China Power Construction's strength breaks the surrounding rock and wins a good reputation with speed and professionalism. Do you really understand? Editor/Peng Xue