Abstract: Massive water volume occurred during the excavation of No. 4 ventilation shaft of the Tianshan Shengli tunnel, leading to the construction stop. Considering the engineering characteristics of the large inclination angle, small crack opening, and weak slurry intake of waterrich marble strata, a steeply inclined marbleenhanced permeability drainage grouting model is constructed. Then, based on the generalized Bingham fluid constitutive equation, a diffusion transport equation considering the rheological characteristics of marble fracture slurry is proposed. The equation demonstrates that the inclination angle of the crack, initial and secondary splitting pressures, crack water pressure, design splitting diffusion distance, and timevarying viscosity of the slurry are the key factors affecting the grouting pressure. On this basis, key grouting parameters and construction techniques are determined, and key technologies such as highpressure water pulse fracturing to increase the permeability in rock fracture channels and drainage grouting are used to achieve controlled diffusion of grout in steeply inclined marble fracture channels. After ground pregrouting treatment, methods including simple hydrological observation, borehole television, and fiber optic temperature measurement are used to monitor the water blocking effect of onsite grouting. The geological exposure results demonstrate no obvious water seepage at the excavation face of the vertical shaft, and the water inflow of the shaft after grouting treatment remains under 1 m3/h, ensuring the safe and efficient construction of No. 4 ventilation shaft of the Tianshan Shengli tunnel. The engineering practice shows that grouting water blocking technology based on enhanced splitting drainage exhibits a remarkable effect, thus providing a novel idea for the treatment of water inrush disasters in waterrich and steep marble strata.

Key words:  tunnel engineering, steeply inclined marble, waterrich strata, fracture grouting, effect analysis