도로 암반 절취사면에 대한 산 발생능력 평가의 사례연구

초록

Acid rock drainage (ARD) developed as a result of road construction imposes various engineering, environmental, and social problems. Engineering impacts from ARD, the product of atmospheric oxidation of rock-forming sulfide minerals, including degradation of surface water quality, disintegration of construction materials, and structural damage of buildings, have been documented widely around the world. Evaluation of acid producing potential of earth materials is strongly suggested as an essential step in the pre-design stage of construction works especially in the vicinity of mining areas. To characterize the ARD and to evaluate acid producing potential of road-cut rocks, samples of rocks and water were collected from two road-cut sites of shale to phyllite showing such visual indicators of ARD as orange precipitates along streambed and rocks. Acid Base Accounting (ABA) and Net Acid Generation (NAG) test, the most commonly applied static test to evaluate the potential acidity, and X-ray diffraction (XRD) and X-ray Fluorescence (XRF) analysis were performed for fifteen rock samples. As a result, in terms of NAPP (Net Acid Producing Potential) and NAGpH (pH of Net Acid Generation), seven, four, and four rock samples were classified into a PAF (potentially acid forming) group, a NAF (non-acid forming) group, and an uncertain group, respectively. Water samples with low pH of 4.4, low dissolved oxygen (DO), and high contents of heavy metals and sulfate ion confirmed that the classification scheme by NAPP and NAGpH can be a reliable tool to assess acid producing potential of rock mass.

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