ABSTRACT:
This paper describes the variation of groundwater rate and level surrounding of tunnel by numerical modeling and the non-point source of contaminants generated from the tunnel under construction and operations by field investigation. Generally, it is difficult to measure the groundwater rate and non-point sources correctly as they enter the underground. The tunnel which was applied to this analysis was one of sections in Busan subway tunnel, a regional river is passing over this applied section. The ground water level is located in ground level -3.0m. The modeling results show that an approximately 2.11 m3/min/km is flow into tunnel immediate after tunnel excavation, and inflow rate gradually converges to smaller value than maximum 1.45 m3 min/km after 6 months from the start of tunnel excavation. Comprehensive samplings and analysis for non-point source of contaminants were conducted in the environs of tunnel under construction and operations in under to determine the most significant non-point source of toxic pollutants. From the filled investigations and laboratory chemical analysis, the contaminants of road and roadside soils due to the non-point source of contaminants generated from the tunnel work were analyzed and summarized.
1 INTRODUCTION
Tunneling beneath the groundwater table causes changes in the state of stress and the pore water pressure regime. In such tunneling problems, there are three important issues that have to be addressed during design and construction stages including construction, stability, and environmental issues. First, water inflows during tunneling significantly hamper the tunneling works, thus resulting in a global increase in the construction costs. Second, as the stress-strain-strength characteristics of the surrounding ground are governed by the effective stress, the change in the pore water pressure regime during the tunneling process can affect the short- and long-term tunnel stability.