• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.117-122
• /
• 2003

Every year in domestic slope failure caused by rainfall is happening frequently. Specially, causable failure accident by localized downpour accompanied when summer rainy season period and produces typhoon gets damage of large scale human life and property. Failure happened at slope of 121 places ranged whole country national highway by No.15 typhoon Rusa that strike whole country during 3 days from August 30, 2002. Slope failure that happen by typhoon are judged for major cause to effect of ground saturation and surface water by localized downpour. In this research, failure characteristic was analyzed to target 20 places attaining site investigation among failure slope. As a result, erosions by surface water was construed for major cause of failure and judged for direct relation in failure slope weathering and topography Also, result that analyze inclination of failure part, in the case of ripping rock, inclination of failure side is forming Incline of the lowest 40$^{\circ}$, because surface failure of depth 4m on or so scale happened, it is require that regulating plan gently design standard inclination of weathered rock and soil layer And it is considered that desirable preparation of design standard about measure that help smooth drainage of surface water and can restrain percolation in ground to reduce failure damage by rainfall.

• Geomechanics and Engineering
• /
• 제19권1호
• /
• pp.49-60
• /
• 2019

Crack instability propagation during coal and rock mass failure is the main reason for electromagnetic radiation (EMR) generation. However, original cracks on coal and rock mass are hard to study, making it complex to reveal EMR laws and mechanisms. In this paper, we prefabricated cracks of different inclinations in coal and rock samples as the analogues of the native cracks, carried out uniaxial compression experiments using these coal and rock samples, explored, the effects of the prefabricated cracks on EMR laws, and verified these laws by measuring the surface potential signals. The results show that prefabricated cracks are the main factor leading to the failure of coal and rock samples. When the inclination between the prefabricated crack and axial stress is smaller, the wing cracks occur first from the two tips of the prefabricated crack and expand to shear cracks or coplanar secondary cracks whose advance directions are coplanar or nearly coplanar with the prefabricated crack's direction. The sample failure is mainly due to the composited tensile and shear destructions of the wing cracks. When the inclination becomes bigger, the wing cracks appear at the early stage, extend to the direction of the maximum principal stress, and eventually run through both ends of the sample, resulting in the sample's tensile failure. The effect of prefabricated cracks of different inclinations on electromagnetic (EM) signals is different. For samples with prefabricated cracks of smaller inclination, EMR is mainly generated due to the variable motion of free charges generated due to crushing, friction, and slippage between the crack walls. For samples with larger inclination, EMR is generated due to friction and slippage in between the crack walls as well as the charge separation caused by tensile extension at the cracks' tips before sample failure. These conclusions are further verified by the surface potential distribution during the loading process.

• 한국지반환경공학회 논문집
• /
• 제2권3호
• /
• pp.71-80
• /
• 2001

쇄석말뚝-매트로 구성된 기초시스템은 지지력이 여러 인자에 의해 영향을 받게 되어 기초지반과 말뚝체의 상호작용을 정량적으로 평가하기에 어려움이 있다. 복합지반의 지지력은 말뚝-흙 경계면의 측방응력에 의해 발생되므로 쇄석말뚝의 거동을 규명하기 위해서는 경계면에서 발생하는 수평저항력에 영향을 미치는 인자들에 대한 평가가 필요하다. 또한, 말뚝간격과 근입비, 파괴각 등 기하학적 요인들도 영향을 미치는 것으로 알려져 있다. 따라서, 본 논문에서는 쇄석말뚝-매트로 구성된 기초시스템의 선단지지 단일말뚝과 군말뚝에 대한 실내모형실험을 통하여 쇄석말뚝의 한계깊이를 측정하고 파괴각에 영향을 미치는 인자들을 평가하였다. 또한, 실내실험결과를 이론식과 비교하였으며 유한요소해석을 통해 파괴거동을 평가하여 실내모형실험의 타당성을 검증하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.409-416
• /
• 2005

Design analysis for underground spaces requires evaluating stability related to tunnel collapses. A failure mode is one of the critical factors in the conventional methods of stability analysis. Therefore identification of failure modes is essential in securing safe construction in the phase of design analysis, instrumentation planning and implementation of reinforcing measures. In this study failure modes at the tunnel heading in granular soils are investigated using physical model tests and numerical simulation for various tunnel depths and ground surface inclinations. Test results indicated that the effect of depth and inclination of ground surface on a failure mode are significant. It is identified that, with an incase in depth, failure modes become localized in a region close to the tunnel. It is also known that an increase in the inclination of ground surface results in inclined and wide failure modes.

• 한국터널지하공간학회 논문집
• /
• 제7권3호
• /
• pp.197-207
• /
• 2005

지하공간의 설계는 막장파괴와 관련한 안정성에 대한 평가를 필요로 한다. 막장파괴모드는 전통적인 안정성 평가법에서 중요하게 다루어져 왔다. 본 연구에서는 점착력이 없는 토사지반에 대한 모형실험을 실시하여 토피고와 지반경사의 변화에 따른 터널막장의 종방향 파괴모드를 파악하고자 하였다. 모형실험은, 대형지하공간의 폭원이 충분히 크다는 가정 하에 평면변형조건의 터널 축방향 굴착면 모델에 대하여 실시되었다. 실험결과 토피고와 지반경사는 파괴모드에 중요한 영형을 미치는 것으로 나타났다. 토피고가 증가할수록 지반의 파괴영역이 감소하여 국부 전단 파괴의 형태를 보였다. 또, 지반경사가 증가할수록 굴착면과 사면방향으로 확대되는 유형의 파괴모드를 확인할 수 있었다. 실험모델을 수치해석 모델로 재현하는 해석을 실시하였고, 이로부터 수치해석법을 통해서도 굴착면의 파괴모드의 추정이 가능함을 보였다.

• 한국농공학회지
• /
• 제39권1호
• /
• pp.112-121
• /
• 1997

The aim of this study was to analyze the slope stability relating to the failure of cut slopes and the characteristics of stress-strain relations obtained by limit equilibrium method, finite element method, and stereographic projection method for the reinforced cut slopes. The following conclusions were made : 1.To use stereographic projection method led to little possibility to take the toppling and wedge failure while to use the other methods led to the failure. It was recommended to reduce the slope inclination from 1:1 to 1: 1.5~1 :1.8 and adopt coir mesh method to protect the slope surface. position with the horizontal displacement after final excavation moved to the excavation base. The maximum shear strain values concentrated at the excavation base indicated the possibility to induce the local failure. 3. It was recommended that the slope inclination for blast rock with the slope height larger than l0m was 1: 0.5, 1:1, and 1: 1~1 :1.5 for hard rocks, soft and ordinary rocks, and ripping and soils, respectively. 4. Berm width criteria for blast rock with the slope height larger than l0m were recommended as follow : 2~3m per 20m slope height for hard rocks, 1 ~2m per l0m slope height for soft and ordinary rocks, 1 ~ l.5m per 5m slope height for ripping and soils.

• 구강회복응용과학지
• /
• 제19권2호
• /
• pp.105-108
• /
• 2003

After stage-two surgery, the highest incidence of failure has been attributed to implant overload. However, the biomechanical factors cited inthe literature that contribute to implant overload, such as bone type, cuspal inclination, horizontal offset, maxillary compared to mandibular arch, the inclusion of natural teeth within the prosthesis, and occlusal harmony are superimposed on physiologic variations. Following two cases, including reduction of cuspal inclination and usage of modified incisal pin, showed a method of contouring occlusal surface for reduction of unpreditable implant overload.

• Geomechanics and Engineering
• /
• 제28권2호
• /
• pp.181-195
• /
• 2022

Roughness and joint inclination angle are the important factors that affect the strength and deformation characteristics of jointed rock mass. In this paper, 3D printer has been employed to make molds firstly, and casting the jointed specimens with different joint roughness coefficient (JRC), and different joint inclination angle (α). Conventional triaxial compression tests were carried out on the jointed specimens, and the influence of JRC on the strength and deformation parameters was analyzed. At the same time, acoustic emission (AE) testing system has been adopted to reveal the AE characteristic of the jointed specimens in the process of triaxial compression. Finally, the morphological of the joint surface was observed by digital three-dimensional video microscopy system, and the relationship between the peak strength and JRC under different confining pressures has been discussed. The results indicate that the existence of joint results in a significant reduction in the strength of the joint specimen, JRC also has great influence on the morphology, quantity and spatial distribution characteristics of cracks. With the increase of JRC, the triaxial compressive strength increase, and the specimen will change from brittle failure to ductile failure.

• Geomechanics and Engineering
• /
• 제31권1호
• /
• pp.71-86
• /
• 2022

In Taiwan, an efficient approach for enhancing the stability of colluvium slopes is the drilled shaft method. For slopes with drilled shafts, the soil arching effect is one of the primary factors influencing slope stability and intertwines to the failure mechanism of the pile-soil system. In this study, the contribution of soil arching effect to slope stability is evaluated using the FEM software (Plaxis 3D) with the built-in strength reduction technique. The result indicates the depth of the failure surface is influenced by the S/D ratio (the distance to the diameter of piles), which can reflect the contribution of the soil arching effect to soil stability. When α (rock inclination angles)=β (slope angles) is considered and the S/D ratio=4, the failure surface of the slope is not significantly influenced by the piles. Overall, the soil arching effect is more significant on α=β, especially for the steep slopes. Additionally, the soil arching effect has been included in the proposed stability charts. The proposed charts were validated through two case studies, including that of the well-known Woo-Wan-Chai field in Taiwan. The differences in safety factor (FoS) values between the referenced literature and this study was approximately 4.9%.

• 한국지반공학회논문집
• /
• 제25권11호
• /
• pp.39-51
• /
• 2009

본 연구는 지반변형을 일으키는 경사모래지반에 매설된 사각형 수동열말뚝의 모형실험에 대한 것이다. 실험은 지반의 경사각을 조절하여 지반파괴를 유도 하였고, 말뚝의 형상, 위치, 간격을 달리하여 말뚝 거동을 측정하였다. 그 결과 수동말뚝에 작용하는 토압과 수평저항력 그리고 지반변형억제 효과를 확인하였다. 전면 폭이 넓은 B-type 말뚝이 측면 폭이 넓은 H-type 말뚝보다 지반변형억제 효과가 크게 나타났다. 사면경사에 따른 수평저항력 그래프를 이용하여 사면의 파괴각, 말뚝과 지반의 분담력을 알 수 있다.