• Geomechanics and Engineering
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• 제9권6호
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• pp.815-827
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• 2015

The mechanical behavior of soil and soil-rock mixture is investigated via the discrete element method. A non-overlapping combination method of spheres is used to model convex polyhedron rock blocks of soil-rock mixture in the DEM simulations. The meso-mechanical parameters of soil and soil-rock interface in DEM simulations are obtained from the in-situ tests. Based on the Voronoi cell, a method representing volumtric strain of the sample at the particle scale is proposed. The numerical results indicate that the particle rotation, occlusion, dilatation and self-organizing force chains are a remarkable phenomena of the localization band for the soil and soil-rock mixture samples. The localization band in a soil-rock mixture is wider than that in the soil sample. The current research shows that the 3D discrete element method can effectively simulate the mechanical behavior of soil and soil-rock mixture.

• Geomechanics and Engineering
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• 제1권2호
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• pp.169-178
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• 2009

Due to the enormous amount of fills required, broken rock-fine grain soil mixtures have been increasingly used in the construction of high-fill foundations for airports, railways and highways in the mountain areas of western China. However, the compressibility behavior of those broken rock-fine grain soil mixtures remains unknown, which impose great uncertainties for the performance of those high-fill foundations. In this research, the mixture of broken limestone and a fine grain soil, Douposi soil, is studied. Large oedometer tests have been performed on specimens with different soil content. This research reveals the significant influence of fine grains on the compressibility of the mixture, including immediate settlement, creep, as well as wetting deformation.

• 한국철도학회논문집
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• 제12권2호
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• pp.183-189
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• 2009

경부고속철도 2단계 구간은 콘크리트궤도 형식으로 건설되고 있다. 콘크리트궤도는 궤도의 강성 구조적 특징으로 인하여 잔류침하 규정이 엄격하게 적용되고 있다. 궤도의 잔류침하는 궤도를 지지하는 하부구조인 노반과 원지반으로부터 기인된다. 암버럭과 흙 재료로 건설되고 있는 노반의 잔류침하는 현장다짐품질에 따라 원지반을 포함한 총 잔류침하의 중요한 부분이 될 수 있다. 따라서 암버럭 토사 혼합성토재로 이루어진 노반에서의 잔류침하를 최소화하는 것은 콘크리트궤도의 성공적인 건설을 위하여 중요한 요소 중 하나이다. 본 논문에서는 암버럭-토사 혼합성토재의 거동을 이해하기 위하여 총 31회의 대형다짐시험을 수행하였다. 다짐시료는 건설 중인 2개 현장으로부터 혈암과 이암을 주성분으로 하는 노반 재료를 채취하여 조성하였고, 다짐시험은 암 종류, 4번체 통과율, 최대입경, 함수비를 변화시키면서 수행하였다. 시험결과로부터 혼합성토재의 최대건조단위중량에 영향을 미칠 수 있는 인자들에 대한 평가를 수행하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1190-1200
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• 2010

A method was developed to determine resilient modulus for crushed rock-soil mixtures whose usage has been increased recently without engineering specifications. The method is based on the subtle different modulus called nonlinear dynamic modulus and was lately implemented in residual soils and engineered crushed-stones. Hereby. the same method was expanded to crushed rock-soil mixtures containing as large grain diameter as 300mm. The method utilize field direct-arival tests for the determination of maximum Young's modulus, and a large scale free-free resonant column test, which is recently developed to is capable to test as large grain diameter as 25mm, for modulus reduction curves. The prediction model of resilient modulus was evaluated for crushed rock-soil mixtures of a highway construction site at Gimcheon, Korea.

• 대한토목학회논문집
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• 제32권5C호
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• pp.193-198
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• 2012

본 연구는 밀양과 울산지역에 건설 중인 2개소의 도로현장을 택하여 현장시험을 통한 암석과 토사가 혼재되어 있는 경우에 대한 토량환산계수의 측정 및 단위중량의 변화 등을 검토한 것이다. 시험결과, 암석과 토사가 동등한 비율로 혼합한 경우에 최대 단위중량을 얻을 수 있었으며, 암석만의 경우와 비교한 결과 2개소의 현장에서 각각 19%와 18%의 단위중량이 증가되었다. L값은 표준품셈에서 제시된 값보다 4~11% 크게 나타났으나, C값은 약 13~20% 낮게 나타냄을 알 수 있었다. 이는 최근 다짐장비의 대형화 및 다짐작업의 합리화에 기인되는 현상이므로 토공작업에서 이에 대한 고려가 있어야 할 것으로 판단된다. 또한 운반 시 암석과 토사가 5:5로 혼합되었을 때 가장 높은 단위중량을 나타내어 유리한 조건이 됨을 알 수 있었다.

• 한국도로학회논문집
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• 제12권4호
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• pp.147-155
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• 2010

재활용된 암버력-토사의 회복탄성계수 예측모델이 개발되었다. 반복삼축시험을 통한 회복탄성계수의 전통적 평가방법은 큰 입경을 가진 자갈에는 실현 불가능하다. 미세한 차이가 있는 비선형 전단탄성계수를 이용하여 회복탄성계수를 산출하는 대체기법을 제안하였다. 현장에서 측정한 최대전단탄성계수와 대형공진주 시험으로 구한 감소곡선을 이용하여 회복탄성계수 예측모델을 개발하였다. 이 예측모델을 김천의 고속도로공사현장에서 재활용한 암버력-토사에 적용하여 모델인자 $A_E,\;n_E,\;{\varepsilon}_r,\;{\alpha}$를 각각 9618, 0.47, 0.0135, 0.8로 제안하였다.

• Geomechanics and Engineering
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• 제9권4호
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• pp.483-498
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• 2015

This article describes a new in-situ load test called the Hydraulic Cylinder Test (HCT) and its application to determine the geotechnical properties of soil-rock mixtures. The main advantages of the test are its easy implementation, speed of execution and low-cost. This article provides a detailed description of the equipment and the test procedure, and examines a case study of its application to determine the geotechnical properties of an earth-filled dam for a tailings pond. The containment dams of the ponds are made from blocks of gypsum and marl, obtained from the excavation of the ponds, mixed in a matrix of sands and clays. The size of the rocks varies between 1 and 30 cm. The HCT is particularly useful for determining the geotechnical properties of this type of soil-rock mixture. Nine HCTs were carried out to determine its strength (c, ${\phi}$) and deformation (B, G) properties. The results obtained were validated using the Bim strength criterion, recently proposed, and some pressure meter tests carried out beforehand. The properties obtained are used to analyze the stability of the dam using computer simulations and a modification to its design is proposed.

• 한국환경복원기술학회지
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• 제5권4호
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• pp.70-79
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• 2002

This study was conducted to develop environmental restoration methods for the ecological restoration of the rock exposed steep cut-slopes using native woody plants seeds by the hydro-seeding with artificial soil media. The main results are summarized as follows; 1. Quercus spp. seeded after seed treatment germinated over 80% and most of them grew well until one year. So, Quercus spp. can grow at the extremely dry rock exposed slopes revegetated by hydro-seeding with soil-fertilizer-seed mixed media. 2. The germinated seedlings grew well at the slopes oriented southeast. But in case of the survival ratio of the germinated seedlings, northwestward slopes was the best. 3. In case of the using pot seedlings of the Miscanthus sinensis var. purpurascens, it shows more beautiful scenery than the area using cool-season grasses. 4. As the results of the experiment, Albizzia julibrissin, Quercus spp. and Lespedeza crytobotrya can be useful at the restoration and revegatation of the cut-slopes. 5. At the results of the seed mixture experiment, cool-season grasses covered the ground quickly, but slowly germinated Quercus spp. and Lespedeza crytobotrya formed under story vegetation. Also, Albizzia julibrissin formed upper story vegetation will be replaced by Quercus spp. slowly.

• Geomechanics and Engineering
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• 제18권4호
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• pp.353-362
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• 2019

Soil-rock mixture (S-RM) is an inhomogeneous geomaterial that is widely encountered in nature. The mechanical and physical properties of S-RM are important factors contributing towards different deformation characteristics and unstable modes of the talus slope. In this paper, the equivalent substitution method was employed for the preparation of S-RM test samples, and large-scale triaxial laboratory tests were conducted to investigate their mechanical parameters by varying the water content and confining pressure. Additionally, a simplified geological model based on the finite element method was established to compare the stability of talus slopes with different strength parameters and in different excavation and support processes. The results showed that the S-RM samples exhibit slight strain softening and strain hardening under low and high water content, respectively. The water content of S-RM also had an effect on decreasing strength parameters, with the decrease in magnitude of the cohesive force and internal friction angle being mainly influenced by the low and high water content, respectively. The stability of talus slope decreased with a decrease in the cohesion force and internal friction angle, thereby creating a new shallow slip surface. Since the excavation of toe of the slope for road construction can easily cause a landslide, anti-slide piles can be used to effectively improve the slope stability, especially for shallow excavations. But the efficacy of anti-slide piles gradually decreases with increasing water content. This paper can act as a reference for the selection of strength parameters of S-RM and provide an analysis of the instability of the talus slope.

• 한국지반공학회논문집
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• 제25권8호
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• pp.95-106
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• 2009

본 연구에서는 암석과 흙이 혼합된 성토재료를 대상으로 다짐 시 함수조건 및 입도조건 등에 따라 Wetting이 성토제체의 장기압축침하에 미치는 영향을 중심으로 검토하였다. 그 결과 완전 침수를 모사한 경우 침하량이 상대적으로 매우 크게 나타났으며, 강우침투와 같이 반복적인 함수비의 증가 시에도 반복적인 침하가 관측되었다. 반면 습윤상태에서 다져진 시료나 세립분이 없는 재료의 경우에는 Wetting에 의한 침하량이 상대적으로 적게 발생되는 것을 확인할 수 있었다. 또한 동결 융해가 반복되는 경우 입자파쇄의 가속화로 압축침하가 지속적으로 발생되고 있는 것을 확인할 수 있었다. 결론적으로 이와 같은 재료에서의 장기적인 성토체 압축침하거동에는 크리프의 영향보다 함수비 증가나 반복적인 동결융해 조건이 더 큰 영향을 미치고 있는 것으로 나타났다.