• Geomechanics and Engineering
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• 제14권4호
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• pp.337-344
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• 2018

The study of the mining effect influenced by a normal fault has great significance concerning the prediction and prevention of fault rock burst. According to the occurrence condition of a normal fault, the stress evolution of the working face and fault plane, the movement characteristics of overlying strata, and the law of fault slipping when the working face advances from footwall to hanging wall are studied utilizing UDEC numerical simulation. Then the inducing-mechanism of fault rock burst is revealed. Results show that in pre-mining, the in situ stress distribution of two fault walls in the fault-affected zone is notably different. When the working face mines in the footwall, the abutment stress distributes in a "double peak" pattern. The ratio of shear stress to normal stress and the fault slipping have the obvious spatial and temporal characteristics because they vary gradually from the higher layer to the lower one orderly. The variation of roof subsidence is in S-shape which includes slow deformation, violent slipping, deformation induced by the hanging wall strata rotation, and movement stability. The simulation results are verified via several engineering cases of fault rock burst. Moreover, it can provide a reference for prevention and control of rock burst in a fault-affected zone under similar conditions.

• 지질공학
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• 제26권4호
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• pp.571-581
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• 2016

To understand the mechanical properties of fault rocks, data from 584 in situ and laboratory tests on fault rocks from 33 tunnels were analyzed. The unit weights of the fault rocks range from 17.3 to $28.2kN/m^3$ and the cohesion and friction angles vary from 5 to 260 kPa and $14.7^{\circ}$ to $44.0^{\circ}$, respectively. The modulus of deformation and elasticity were generally < 200 MPa. In most cases, the uniaxial compressive strength was < 0.5 MPa, and Poisson's ratios were mainly 0.20-0.35. The mechanical properties of individual rock types were analyzed using box plots, revealing that the cohesion values and friction angles of shale and phyllite have relatively wide inter-quartile ranges and that the modulus of deformation and elasticity of shale have the lowest values of all rock types. In the analysis of mechanical properties by components of fault rocks, the largest values were shown in damage zones of individual rock types.

• 터널과지하공간
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• 제19권2호
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• pp.132-145
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• 2009

암반내 존재하는 단층은 암반의 거동에 미치는 영향이 매우 크기 때문에 암반사면, 터널과 같은 암반구조물의 설계 및 시공에 있어서 단층특성에 대한 조사는 무엇보다 중요하다 할 수 있다. 그러나 설계단계에서 이러한 특성을 파악하기에 한계가 있기 때문에 시공중 막장관찰과 추가지반조사를 통하여 터널주변에 존재하는 단층의 분포 및 공학적 특성에 대하여 조사하여야 한다. 본 연구에서는 운모편암지역에서의 대단면 터널 공사중 설계시 파악되지 않은 대규모 스러스트 단층대가 확인됨에 따라, 단층대의 특성을 규명하기 위하여 다양한 지질조사 및 현장시험을 실시하였다. 이러한 지반조사결과를 바탕으로 단층의 성인, 구조지질적 분포특성 및 단층암의 공학적 특성을 파악하였으며, 단층대 통과구간에서 안전하게 터널을 굴착할 수 있도록 합리적인 지보 및 보강대책을 수립하였다.

• Geomechanics and Engineering
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• 제23권2호
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• Geomechanics and Engineering
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• 제24권5호
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• pp.471-478
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• 2021

Water damage is one of the five disasters that affect the safety of coal mine production. The erosion of rocks by water is a very important link in the process of water inrush induced by fault activation. Through the observation and experiment of fault filling samples, according to the existing rock classification standards, fault sediments are divided into breccia, dynamic metamorphic schist and mudstone. Similar materials are developed with the characteristics of particle size distribution, cementation strength and water rationality, and then relevant tests and analyses are carried out. The experimental results show that the water-rock interaction mainly reduces the compressive strength, mechanical strength, cohesion and friction Angle of similar materials, and cracks or deformations are easy to occur under uniaxial load, which may be an important process of water inrush induced by fault activation. Mechanical experiment of similar material specimen can not only save time and cost of large scale experiment, but also master the direction and method of the experiment. The research provides a new idea for the failure process of rock structure in fault activation water inrush.

• Geomechanics and Engineering
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• 제29권2호
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• pp.145-154
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• 2022

Complex geological conditions have a great influence on the mining of coalbed methane (CBM), which affects the extraction efficiency of CBM. This investigation analyzed the complicated geological conditions in the Liujia CBM block of Fuxin. A geological model of heterogeneities CBM reservoirs was established to study the influence of strike direction of igneous rocks and fault structures on horizontal well layout. Subsequently, the dual-porosity and dual-permeability mathematical model was established, which considers the dynamic changes of porosity and permeability caused by gas adsorption, desorption, pressure change. The results show that the production curve is in good agreement with the actual by considering gas seepage in matrix pores in the model. Complicated geological structures affect the pressure expansion of horizontal wells, especially, the closer to the fault structure, the more significant the effect, the slower the pressure drop, and the smaller the desorption area. When the wellbore extends to the fault, the pressure expansion is blocked by the fault and the productivity is reduced. In the study area, the optimal distance to the fault is 70 m. When the horizontal wellbore is perpendicular to the direction of coal seam igneous rock, the productivity is higher than that of parallel igneous rock, and the horizontal well bore should be perpendicular to the cleat direction. However, the well length is limited due to the dense distribution of igneous rocks in the Liujia CBM block. Therefore, the horizontal well pumping in the study area should be arranged along the direction of igneous rock and parallel plane cleats. It is found that the larger the area surrounded by igneous rock, the more favorable the productivity. In summary, the reasonable layout of horizontal wells should make full use of the advantages of igneous rock, faults and other complex geological conditions to achieve the goal of high and stable production.

• 한국방재학회 논문집
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• 제1권1호
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• pp.117-125
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• 2001

비활성 그리고 황성 단층지역의 내부와 주변에서 발생하는 응력장의 변화에 대한 수치적 분석이 수행되었다. 존재하는 비활성 단층지역 근처에서의 응력장은 단층의 방향과 단층화된 암반과 주위의 비단층화된 암반의 탄성적 특성 사이의 대조에 따라 변화한다. 활성 단층지역 주위의 응력장에 대한 분석에서, 만약 단층지역의 항복응력이 초과된다면, 단층지역 내에서의 국부화된 전단응력은 주위의 비단층화된 암반에서의 평균응력 보다 작게 되는 단층 내에서의 평균응력의 감소를 유발시킨다. 따라서 이러한 응력경사는 단층지역내로 유체의 흐름을 기대할 수 있다.

• 한국지반환경공학회 논문집
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• 제4권4호
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• pp.45-51
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• 2003

암반 내에서 주입재는 토사지반에서와는 달리 절리면을 따라 맥상으로 주입되며 그 결과 암반 내의 불연속면의 특성을 변화시키게 된다. 그러므로 그라우팅 후 암반의 변형특성은 주입재가 주입되는 절리의 방향, 절리의 특성, 그리고 현지암반의 응력상태에 따라 달라지게 된다. 즉 그라우팅에 의한 보강효과를 정확히 평가하기 위해서는 암반 내의 불연속면의 특성과 주입재의 특성이 암반의 변형거동에 미치는 영향을 규명하여야 한다. 그러나 현재까지 현장에서 적용되고 있는 그라우팅공법은 시공자의 경험에 의존하고 있으며, 그 효과에 대한 검증도 현장에서의 탄성파속도 측정, 투수시험 등을 통하여 평가하고 있다. 따라서, 본 연구에서는 그라우팅에 의한 댐 기초 암반절리면의 전단변형특성을 파악하기 위해서 자연암석 절리면에 OPC(Ordinary Portland Cement)와 Micro Cement를 각각 주입하여, 주입재의 종류, 절리면 거칠기의 평균진폭(a)에 대한 주입두께(t)를 변화시켜가면서 암석절리면 직접전단시험을 실시한 실험결과들을 비교 분석하여 최대전단강도, 잔류전단강도 등의 전단특성에 미치는 영향에 대하여 검토하였다.

• 터널과지하공간
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• 제16권4호
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• pp.307-312
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• 2006

처분 용기 부식 후 유출된 방사성 핵종은 지하수 유동 경로를 따라 이동하게 된다. 따라서 지하 암반내 지하수 유동 평가는 처분 안전성 평가를 위한 기본적인 요소라 할 수 있다. 본 연구에서는 처분 시스템 폐쇄 후 미래 특정 시점에서 지형의 변화가 지하수 유동 경로에 끼치는 영향을 다공질 매질에서의 지하수 유동 해석 코드인 NAMMU를 이용한 평가를 통해 확인해 보았다. 단열에 인접한 지역에 가상의 처분 시스템을 선정하고 처분 시스템 주위에 존재하는 단열의 재활성화가 발생하는 경우 처분장으로부터의 지하수 유동에 끼치는 영향을 정량적으로 평가해 보았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1022-1028
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• 2008

From the result of precise field investigation and stability examination for the rock slope, following results were acquired. 1. The weathering rock itself, existing fault zone and underground water complexly effect cut slope so that plane destruction may appear by fault zone. 2. The reinforcement force was decided by the result of limit equilibrium. 3. For rock cut slope, the Rock Bolt was judged as the most proper method to the cut slope as comparing/analyzing Rock Anchor, Rock Bolt and method after relaxing the slope.