Abstract
This paper reports the dewatering scheme of a deep excavation in sandy pebble strata. The excavation is in high permeability strata and is close to the Yellow River, making the dewatering difficult during construction. At present, few researchers have specially studied the dewatering scheme of deep excavations in strong permeable strata near the water resource. Field pumping test was conducted before the excavation activity, and the permeability coefficient of the strata was obtained by reverse analysis. According to the characteristics of the project, the dewatering scheme of “ waterproof curtain + base grouting + pumping ” was proposed. The influence of vertical waterproof curtain and base grouting on dewatering was analyzed by numerical simulation. In the construction process, the field water table and ground settlement were measured. The results show that (1) the groundwater table versus permeability coefficient curve shows three different stages and (2) the dewatering scheme of “ waterproof curtain + base grouting + pumping ” is effective for deep excavation in strong permeable strata.
Highlights
Many deep excavations or ventilation shafts have been designed and constructed in the rail transit projects, power tunnels, and water conveyance tunnels [1,2,3]
Field groundwater table and ground settlement were measured, and assembled data verified the results of the numerical simulation
This section mainly focuses on three issues: (i) the influence of vertical waterproof curtain on dewatering, (ii) the influence of base grouting on dewatering, and (iii) the numerical simulation of the proposed dewatering scheme of “waterproof curtain + base grouting + pumping.”
Summary
Many deep excavations or ventilation shafts have been designed and constructed in the rail transit projects, power tunnels, and water conveyance tunnels [1,2,3]. Granata and Leoni [17] reported a case that designed a grout blanket in order to decrease the water inflow from the bottom of the excavation, and the work focused mainly on the grouting activity quality control. It can be seen from the above practices that placing horizontal barriers is conducive to dewatering work when excavation under complex geological conditions. The depth of the shaft reaches 45.1 m, and the horizontal distance between the Yellow River embankment and the shaft center is only 105 m Both numerical simulation method and field observation were adopted in this paper. Field groundwater table and ground settlement were measured, and assembled data verified the results of the numerical simulation
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