关键词: 富水破碎地层, 钢花管静压注浆, 止水, 加固

Abstract: Within the geological condition of the saturated and fracture zone, the construction of hand-dug piles for a highway bridge passing through the existing high-speed railway may not only adversely affect the piled foundation of a high-speed railway viaduct due to the collapse and instability of the hand-dug shaft caused by the broken and low strength of the bedrock and soils. This saturated and fractured zone might also affect the operation of the high-speed railway due to the differential ground settlement caused by the rapid drawdown of the groundwater level. Based on the comprehensive selection of the feasible mitigation methods, the static pressure grouting process by using the perforated steel pipe is adopted. Two circles of the pressure grouting are arranged in triangular spacing at 300 mm and 600 mm, respectively, on the perimeter of the concrete pipe wall of the hand-dug hole piles. The grouting slurry with water-cement ratio of 0.7:1 is used, mixed with 8% water glass, 0.5% salt mixing, 0.1% triethanolamine, and the pressure of the grouting is controlled to be 0.5 MPa～0.8 MPa. The on-site experiments, i.e. monitoring data show that: the filling rate of porosity of in the soil material has been increased by 108.3~162.4%. The coefficient of permeability has been reduced by 80.1% and 76.6%, respectively. No deformation of high-speed rail and the surrounding ground was observed in the construction process, which ensures the safety of high-speed rail during the construction period.