0.1 Project introduction This contract section is the * * contract section of the civil works of the * * (border between Guangxi and Guizhou) - * * highway in Guizhou Province. The starting point of the line is ZK0+000, starting from * * Township, Liping County, Guizhou Province, at the border between Guizhou and Guizhou, passing through Xialuo, Biyi, Meiyang to Guige, and ending at K6+800, with a total length of 5.535km. The main works of this contract section include: subgrade excavation, filling and protection, large and medium bridges, culverts and passages, separated tunnels and double arch tunnels. 0.3 Project characteristics and key points 0.3.1 Project characteristics ⑴ The surrounding environment is complex and the transportation is inconvenient. The terrain along the contract section fluctuates greatly, with high mountains and steep slopes. It is difficult to enter the site, and the construction site layout is limited; There are no expressways or railways along the line, and it is far away from the national highway, so the transportation is inconvenient. (2) The number of T-beam prefabrication is large, and the layout of prefabrication yard is difficult. 558 T-beams are prefabricated in this contract section. Most of the bridges are long-span and high bridges. The height difference between the mountain peak and the river valley is large, and the bank slope is steep. It is difficult to set the T-beam prefabrication yard. (3) The construction along the line has high requirements for environmental protection, water and soil conservation and civilized construction. Natural ecological resources shall be strictly protected during the construction, and random cutting is strictly prohibited. Waste water and waste liquid can be discharged after being treated to meet the standards; The waste disposal area shall be protected as required to prevent water and soil loss; At the same time, strictly abide by the laws and regulations of the local environmental protection department to achieve civilized construction. 0.3.2 Key points of the project (1) Construction of variable cross-section hollow high piers There are 24 variable cross-section hollow heights in this section, the highest of which is 70m. The construction of high piers and the measurement and control of pier shafts are the key points of this section. (2) For the construction of American double arch tunnel, the burial depth of American double arch tunnel is shallow. The surrounding rock is completely weathered and strongly weathered sandy slate. The rock mass is broken, the joint fissures are developed, and the structure is broken and cracked. The stability of the surrounding rock is poor. Collapse is easy to occur during construction, and the construction requirements for collapse prevention are high.
