Full section curtain grouting construction of a tunnel
Content introduction 1 Construction design parameters Applicable conditions of full face curtain grouting: when the tunnel passes through fault fracture zone, the flow of any exploratory hole is>2m3/h, and the total flow is<10m3/h. Before pre grouting, carefully analyze the detailed survey results to detect the underground water, fault fracture zone and fissure zone stratum by advanced geophysical prospecting and drilling. The advance drilling shall be 5-10m ahead of the predicted water inrush, fault fracture zone and fracture zone. ① The grouting scope is 6m away from the tunnel excavation line, and the grouting section is 30m long. It is divided into three rings. The first ring is 12m long, the second ring is 20m long, and the third ring is 30m long. There are 94 holes in the whole section. After the completion of one grouting section, 6m is reserved as the grout stop rock plate of the next grouting section. ② The grouting holes are arranged in an umbrella shape from the tunnel face along the excavation direction, taking the tunnel axis as the center. The slurry diffusion radius is 2m, the hole bottom spacing is not more than 3m, the opening diameter is φ 115, and the final hole diameter is φ 75. ③ The grouting material is cement water glass double slurry or ultra-fine cement slurry, and the slurry concentration should be adjusted according to geological and hydrological conditions. It is initially proposed as: C: S (volume ratio): 1: (0.6-1.0), cement slurry water cement ratio 0.8:1-1:1, water glass modulus 2.6-2.8, water glass concentration 35Be ',. The grouting pressure is initially proposed to be 0.5-1.5Mpa. ③ Before grouting, φ 108 seamless steel pipe shall be embedded in the grout stop wall or grout stop pan as the orifice pipe, which is 3m long and 20-30cm exposed. 2. Construction technology and measures of full section curtain grouting The construction quality and grouting effect of curtain advance grouting are the guarantee for shallow buried large-span tunnels to pass through buildings safely and smoothly. Therefore, advanced drilling and grouting equipment are used in the curtain grouting construction to ensure the grouting reinforcement effect. At the same time, advance geological prediction and infrared water exploration are added to guide the tunnel construction.
