Special document of bamboo cutting tunnel construction
1.1 Geographic location The tunnel site of XX tunnel is located in Nanshan Village, XX Town, XX County, XX Province, with a design speed of 80km/h. The left line is 800m long (ZK48+960 ～ ZK49+760), including 10m bamboo cut tunnel door and 8m open cut tunnel; The right track is 826m long (YK48+950~YK49+776), including 10m bamboo cut tunnel door and 8m open tunnel. XX tunnel is designed as a separated tunnel with standard spacing. The tunnel entrance line spacing is 26.2m, and the exit line spacing is 18.1m. The maximum burial depth of the left line is 57m, and the right line is 55m. The horizontal alignment of the left line of the tunnel is R-1400, A-550, R - ∞; the horizontal alignment of the right line of the tunnel is R-1350, A-530, R - ∞. The longitudinal slope of the left line of the tunnel is 2%, - 0.6% herringbone slope, and the longitudinal slope of the right line is 2% one-way slope. 1.2 Tunnel topography and geological conditions (1). The meteorological tunnel site is located in the southeast of XX Province, in the south central part of XX and the west side of the main peak of XX. It is a temperate continental climate with four distinct seasons. It is hot and rainy in summer and cold in winter. The temperature difference between day and night is large. The annual average temperature is 10.3 ° C. The coldest month is January, and the lowest temperature is - 22 ° C; The average daily precipitation is 54.7mm, and the maximum precipitation is 126.8mm; The maximum depth of frozen soil is 104cm. The frost free period is 110~180 days. ⑵ Hydrogeological conditions The hydrogeological conditions in the tunnel site area are relatively simple, with variable annual surface water, scarce and concentrated precipitation, large evaporation, mostly discharged by surface water, and rarely recharged by groundwater. The groundwater in the tunnel site area is controlled by many factors, such as topography, formation lithology, geological structure, meteorology, hydrology, etc. It is mainly pore phreatic water and bedrock fissure water, and the water volume is generally small. The groundwater is mainly supplied by atmospheric precipitation. The surface and groundwater discharge conditions are good, and the groundwater volume is poor, so the impact on tunnel construction is small. However, during construction in rainy season, a small amount of bedrock fissure water may infiltrate. ⑶ Engineering geological conditions Tunnel portal section and left line ZK49+050 ～ ZK49+100, right line YK49+050 ～ YK49+120 tunnel body section are mainly composed of strongly weathered and moderately weathered gneiss. Affected by regional fault F3, rock mass integrity is poor, in cataclastic structure, joint fissures are developed, rock mass is broken, and self stability is poor. The left line ZK49+100 ～ ZK49+760 and the right line YK49+120 ～ YK49+776 tunnel body sections are mainly composed of pebbles and loess, which are loose in structure and difficult to form a tunnel. Class IV surrounding rock accounts for 7.4% of the tunnel, and Class V surrounding rock accounts for 92.6% of the tunnel. See Table 1.2.1 for tunnel surrounding rock classification Table 1.2.1 XX Tunnel surrounding rock classification Table No. Tunnel name Start and end Stake number Surrounding rock grade length (m) ⅤⅣⅢ 1 XX Tunnel left line ZK48+958 ～ ZK49+050 92 ZK49+050 ～ ZK49+100 50 ZK49+100 ～ ZK49+760 660 2 XX Tunnel right line YK48+949 ～ YK49+050 101 YK49+050 ～ YK49+120 70 YK49+120 ～ YK49+776 656 as a percentage of the total length (%) 92.6 7.4 1.3 Technical standard highway grade: two-way four lane expressway; Tunnel design driving speed: 80Km/h Tunnel construction clearance: single hole clear width: 0.75+0.5+3.75 × 2+0.75+0.75=10.25 m Tunnel clear height: 5.0m Tunnel pedestrian crossing clearance: clear width: 2.0m, clear height: 2.5m 1.4 Project characteristics XX tunnel is the control project of this bid section, with the following characteristics: (1) Affected by regional fault F3, rock mass integrity is poor, in a cataclastic structure, The joints are well developed, the rock mass is broken, and the self stability is poor. (2) The left line ZK49+100 ～ ZK49+760 and the right line YK49+120 ～ YK49+776 tunnel body sections, the surrounding rock is mainly composed of pebbles and loess, with loose structure, shallow burial depth, and difficult tunneling. Grade V surrounding rock accounts for 92.6% of the tunnel. 1.5 Project difficulties (1) Geological advance prediction, surrounding rock monitoring measurement, and through control measurement technology. (2) Geological hazard prevention and treatment technology. (3) Environmental protection and water and soil conservation technology.
