earticle

영어

During a recent earthquake of magnitude of 5.4 in Pohang, Gyeongsangbuk-do Province, 6.5 cm of land creeping was observed on the wire system drawing keen attention from the public. According to the Korea Forest Service’s “Basic Survey on Land Creeping in Pohang” commissioned by the Korean Association of Soil and Water Conservation, only 19 sites of 694 suspected land creeping sites were identified. Consequently there is a need to establish a status survey method for land creeping and to develop algorithms for determining the priority of land creeping. The status survey on land creeping is carried out by the following: 1) a preliminary survey to identify the natural and social environment of the surrounding area based on aerial photos, topography and existing survey data, 2) aa field survey to identify topographical and geological features, vegetation and hydrology in narrow areas including areas undergoing land creeping, 3) a natural environmental impact survey to identify impacts of land creeping on the surrounding natural environment, and 4) a topographical and surface movement survey to identify the situation, range, direction and amount of movement of land creeping. A mechanism analysis is also carried out to determine the movement mechanism of a block undergoing land creeping and to quantitatively identify the relevant factors affecting land creeping activity. The mechanism analysis is carried out by the following: 1) a geological survey (geophysical exploration, boring survey, and geophysical logging) to determine the necessary construction methods for land creeping prevention, 2) a survey on soil characteristics (intrusion experiment, soil and rock experiment, clay mineral experiment, age dating survey, and drilling observation survey), 3) a hydrologic survey (meteorological and ground-water survey), and 4) a survey on land creeping dynamics (surface movement and underground change survey). Currently, the land creeping is caused by a combination of topography, geology, geological structure and ground-water, and various countermeasures should be applied depending on the cause. Prevention works for land creeping are divided into 1) control works (surface-water drainage works, ground-water drainage works, soil retaining works, loading embankment works, gas exclusion works and check dam) to reduce or eliminate factors that cause land creeping and 2) restraint works (pile works, shaft works, and anchor works) to increase the structural stability of land creeping.