• Geomechanics and Engineering
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• 제32권4호
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• pp.375-385
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• 2023

There are many joint fissures distributed in the engineering rock mass. In the process of geological history, the underground rock mass undergoes strong geological processes, and undergoes complex geological processes such as fracture breeding, expansion, recementation, and re-expansion. In this paper, the damage-stick-slip process (DSSP), an analysis model used for rock mass failure slip, was established to examine the master control and time-dependent mechanical properties of the new and primary fractures of a multi-fractured rock mass under the action of stress loading. The experimental system for the recemented multi-fractured rock mass was developed to validate the above theory. First, a rock mass failure test was conducted. Then, the failure stress state was kept constant, and the fractured rock mass was grouted and cemented. A secondary loading was applied until the grouted mass reached the intended strength to investigate the bearing capacity of the recemented multi-fractured rock mass, and an acoustic emission (AE) system was used to monitor AE events and the update of damage energy. The results show that the initial fracture angle and direction had a significant effect on the re-failure process of the cement rock mass; Compared with the monitoring results of the acoustic emission (AE) measurements, the master control surface, key blocks and other control factors in the multi-fractured rock mass were obtained; The triangular shaped block in rock mass plays an important role in the stress and displacement change of multi-fracture rock mass and the long fissure and the fractures with close fracture tip are easier to activate, and the position where the longer fractures intersect with the smaller fractures is easier to generate new fractures. The results are of great significance to a multi-block structure, which affects the safety of underground coal mining.

• Steel and Composite Structures
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• 제17권6호
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• pp.791-801
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• 2014

The effects of anchor on fractured specimens in splitting test are simulated by DDARF method, the results of which are compared with laboratory test results. They agree well with each other. The paper contents also use the laboratory model test. The main research objects are three kinds of specimens, namely intact specimens, jointed specimens and anchored-jointed specimens. The results showed that with the joint angle increased, the weakening effects of jointed rock mass are more obvious. At these points, the rock bolts' strengthening effects on the specimens have become more significant. There is a significant impact on the failure modes of rock mass by the joint and the anchorage.

• Geomechanics and Engineering
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• 제30권6호
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• 터널과지하공간
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• 제12권3호
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• pp.198-209
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• 2002

To assess deep geological environment for the research and development of hish-level radioactive waste disposal, six boreholes of 3" in diameter were installed in two granitic areas. An areal extent of the rock block scale in the study sites was estimated by the lineament analysis from satellite images and shaded relief maps. The characterization of fracture system developed in rock block scale was carried out based on the acoustic televiewer logging in deep boreholes. In the Yuseong site, the granite rock mass was divided into the upper and lower zones at around -160m based on the probabilistic distribution characteristics of the geometric parameters such as orientation, fracture frequency, spacing and aperture size. Since the groundwater flow is dependent on the fracture system in a fractured rock mass, the correlation of the fracture frequency and cumulative aperture size to the hydraulic conductivity was also discussed.

• Geomechanics and Engineering
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• 제18권6호
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• pp.567-574
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• 2019

In order to study the effect of stress and water pressure on the permeability of fractured rock mass under three-dimensional stress conditions, a single fracture triaxial stress-seepage coupling model was established; By using the stress-seepage coupling true triaxial test system, large-scale rock specimens were taken as the research object to carry out the coupling test of stress and seepage, the fitting formula of permeability coefficient was obtained. The influence of three-dimensional stress and water pressure on the permeability coefficient of fractured rock mass was discussed. The results show that the three-dimensional stress and water pressure have a significant effect on the fracture permeability coefficient, showing a negative exponential relationship. Under certain water pressure conditions, the permeability coefficient decreases with the increase of the three-dimensional stress, and the normal principal stress plays a dominant role in the permeability. Under certain stress conditions, the permeability coefficient increases when the water pressure increases. Further analysis shows that when the gob floor rock mass is changed from high stress to unloading state, the seepage characteristics of the cracked channels will be evidently strengthened.

• 지질공학
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• 제22권4호
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• pp.449-458
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• 2012

암반의 구조적 특성에 대한 확고한 이해는 지반구조물의 효과적인 설계 및 유지관리에 있어서 매우 중요한 요소이다. 이는 암반의 강도, 변형 및 수리지질학적 특성이 주로 암반에 존재하는 불연속면의 연결구조 특성에 좌우되기 때문이다. 그동안 암반의 구조적 특성에 대한 연구에 있어서 상당한 진전이 있었음에도 불구하고 불연속면 분포의 복잡성으로 인하여 암반의 삼차원적 구현 및 가시화에 기반한 지질공학적 해석은 드문 실정이다. 이 연구는 암반의 불연속면 및 불연속면의 연결구조를 삼차원적으로 구현하고 가시화하는 기법을 제시하였다. 이를 위하여 원판형으로 가정한 불연속면의 비선형 방정식을 유도하고 불연속면 교차선과 등가파이프의 위치를 산정할 수 있는 대수학적 알고리즘이 제시되었으며, 또한 연산과정을 수행하는 전산모듈이 작성되었다. 이 연구에서 개발한 불연속면 연결구조의 삼차원적 구현 및 가시화 기법은 불연속체 기반의 암반강도 및 변형성에 관한 연구 또는 수리지질학적 특성에 관한 연구를 수행함에 있어서 활용도가 높을 것으로 판단된다.

• 터널과지하공간
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• 제22권2호
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• pp.93-105
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• 2012

균열암반의 등가역학적 물성을 수치해석적으로 결정할 때 2차원 및 3차원 해석을 비교하였다. 수직균열모델과 암반균열망(DFN) 모델이 균열암반의 형상으로 이용되었으며 3차원 모델으로부터 다양한 방향으로 2차원 모델을 절단하여 역학적 물성을 비교하였다. 본 연구의 지질데이터는 영국 셀라필드 지역의 자료를 기본으로 사용하였다. 직교균열모델에서는 컴플라이언스텐서의 변환을 이용한 해석적 방법이 물성결정을 위해 이용되었으며 암반균열망모델에서는 수치실험이 실시되었다. 2차원 모델에서는 균열이 항상 모델평면과 직교한다고 가정하기 때문에 탄성계수는 항상 3차원보다 크게 계산이 되었다. 2차원 해석에서의 포아송비는 3차원 해석보다 큰 값을 나타내는 경향이 있었으나 반대의 경향도 관찰되었다. 본 논문은 3차원 형상을 단순화시켜 사용하는 2차원 해석의 한계를 정량적으로 고찰하였다는데 의의가 있다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.189-190
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• 2005

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.259-260
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• 2005

• 터널과지하공간
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• 제16권1호
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• pp.26-37
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• 2006

본 연구는 절리암반의 통계적 동질성에 대한 정량적 기준으로 절리의 평면밀도 및 길이를 동시에 고려할 수 있는 통계적 모수인 박스프랙털$(D_B)$의 적용성에 대해 논하였다. 길이분포와 평면밀도를 달리하는 총 129개의 절리연결망에서 박스 집계법을 이용하여 절리의 길이분포와 평면밀도의 변화에 따른 $D_B$의 변화특성을 고찰한 결과 $D_B$는 절리의 방향 또는 절리길이의 표준편차 변화에 영향을 받지 않고 전체절리에 대한 평균 절리길이와 평면밀도에만 영향을 받는다는 사실을 검증하였다. 또한 $D_B$는 절리의 길이와 평면밀도의 함수로써 공학적 지구조구 구분의 정량적 척도로 활용될 수 있음을 입증하였다. 본 연구의 현장 적용성을 검토하기 위하여 도로사면 및 지하구조물에서 박스 집계법을 적용한 사례연구를 수행하였다. 통계적 동질구역 구분에 있어서 일반적인 지질조건와 더불어 기존의 분할표 해석과 본 연구의 방법론을 병행하면 절리의 방향성, 평균길이 및 평면밀도가 종합적으로 고려된 공학적 지구조구의 구분이 가능할 것으로 사료된다.