• The Journal of Engineering Geology
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• v.19 no.4
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• pp.517-528
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• 2009

Statistical analyses of cut-slope stability were performed over approximately 5.7 km section along the National road No. 25, which cross-cuts in NW-SE direction the Cheongwon and Boeun-Gun area, Chungbuk. A measure of slope-stability was established by using direct reinforcement and indirect protection methods in whole section. Orientations(dip/dip direction) of the slopes, foliations(bedding), cleavages and joints were measured in total of 30 slope sites. The results analyzed using stereographic projection indicate that major directions of the slopes come out predominantly in three directions: 1) $58^{\circ}/095^{\circ}$, 2) $60^{\circ}/296^{\circ}$ and 3) $59^{\circ}/212^{\circ}$. In analyses of dip direction and frequency of cut-slopes established by reinforcement and protection methods, slopes with dip direction of $80-120^{\circ}$ and $280-320^{\circ}$ mostly occur. However, slopes with dip direction of $0-80^{\circ}$(N and NW) and $120-160^{\circ}$(SE) are not distributed in the study area. Failure aspects were analyzed for three major directions of the slopes, respectively. The results of failure aspects analyzed indicate that slopes in the study area could generate various failures as the results of intersection and/or intersection combination among joints, foliations(bedding) and cleavages. However, possibility of failure in a slope of major direction No. 3 is statistically very low because of low frequency in total number of slopes with the direction and of formation of small scale-slopes geographically, although the slope might generate all aspects of failure-modes.

• Geomechanics and Engineering
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• v.30 no.3
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• pp.281-291
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• 2022

Complex rock masses include various joint planes, bedding planes and other weak structural planes. The existence of these structural planes affects the mechanical properties, deformation rules and failure modes of jointed rock masses. To study the influence of the parameters of a nonpersistent joint network on the mechanical properties and failure modes of jointed rock masses, synthetic rock mass (SRM) technology based on discrete elements is introduced. The results show that as the size of the joints in the rock mass increases, the compressive strength and the discreteness of the rock mass first increase and then decrease. Among them, the joints that are characterized by "small but many" joints and "large and clustered" joints have the most significant impact on the strength of the rock mass. With the increase in joint density in the rock mass, the compressive strength of rock mass decreases monotonically, but the rate of decrease gradually decreases. With the increase in the joint dip angle in rock mass, the strength of the rock mass first decreases and then increases, forming a U-shaped change rule. In the analysis of the failure mode and deformation of a jointed rock mass, the type of plastic zone formed after rock mass failure is closely related to the macroscopic displacement deformation of the rock mass and the parameters of the joints, which generally shows that the location and density of the joints greatly affect the failure mode and displacement degree of the jointed rock mass. The instability mechanism of jointed surrounding rock is revealed.

• Journal of Conservation Science
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• v.37 no.5
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• pp.505-515
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• 2021

In this study, we evaluated the slope stability of the Pohang Daljeon-ri columnar joint (Natural Monuments # 415) and calculated the maximum energy, jumping height and moving distance of rockfalls using a simulation. Based on the results, we established the range of rockfall risk. The slopes of the Pohang Daljeon-ri columnar joint have dip directions of 93.79°, 131.99°, 165.54° and 259.84° from left (SW) to right (NE). Furthermore, they have a fan-like shape. The Pohang Daljeon-ri columnar joints are divided into four sections depending on the dip direction. The measurement results of the discontinuous face show that zone 1 is 125, zone 2 is 261, zone 3 is 262, zone 4 is 43. The results of slope stability analyses for each section using a stereographic projection method correspond to the range of planar and toppling failure. Although it is difficult to diagnose the type of failure, risk evaluation of currently falling rocks requires further focus. The maximum movement distance of a rockfall in the simulation was approximately 66 m and the rockfall risk range was the entire area under slope. In addition, it is difficult to forecast where a rock will fall as it rolls in various directions due to topographic factors. Thus, the installation of measures to prevent falling is suggested to secure the stability based on the results of the rockfall simulations and its probabilistic analysis.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.23-34
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• 2002

Borehole image analysis has been carried out to obtain the detailed geological data by approach of direct observation. Direct application of borehole image analysis inevitably gives rise to a few of restriction of data acquisition due to the limited information within narrow borehole space. Considering the apparent dip of discontinuity surface depending upon the direction, the visualized program of two-dimensional subsurface discontinuities is coded. Borehole image analysis can compensate the distribution of subsurface discontinuity extending into the expected area of investigation. In order to draw subsurface profile in the proposed area of subsurface construction, visualized program is coded as a window GUI (Graphic User Interface) using Fortran and Visual Basic Programming languages. It is to open publicly for the usage of whoever is in want. Discontinuity distribution map is visualized along the Proposed line of tunnel in the Janggye-ri area, Jangsu-gun. Using the visualized program, the limited information from borehole spatially applies into analysis of overall subsurface structures, and the distributional characteristics of discontinuity anticipate at the proposed area. In addition, spacing and extension of joint and depth of discontinuity effecting tunnel safety can be visualized along the direction of the proposed tunnel. These lines of visualization apply design and construction of fundanmental structures.

• The Journal of Engineering Geology
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• v.27 no.2
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• pp.119-124
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• 2017

The waviness of Large Discontinuity rock is the one of important elements that judges the stability of rock slope. When the waviness of large discontinuity is measured in the field, there are many limitations Therefore this research was carried out to measure waviness of large rock discontinuities using 3D laser scanner to supplement this problem. This research established one 3D model that actual X, Y and Z coordinates through the integrated data gained from one that calculates waviness of base lock using CAD program was compared and analyzed to that of disc-clinometer. As its results, the high reliability of results could be recognized as it belongs to mechanical tolerance $1{\sim}2^{\circ}$ and the results belong to the measured values of Mean DIP and Mean are all within $1^{\circ}$. So, the investigation method of waviness of large discontinuity rock face using 3D laser scanner was verified as more prompt, effective and reliable method than conventional direct site measuring method.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.321-328
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• 2009

A optimal reinforcement in the joint rock slope excavation adjacent to an existing tunnel would be influenced by excavation distance from the tunnel, slope angel, and joint conditions but has been empirically determined so far. In this study, large scale model tests were conducted to find out the relationship between load translation on the excavation surface and bebavior of the tunnel according to excavation steps of the jointed rock slope. Consequently, two main parameters, joint dip and sloped angle were investigated in those model tests. From the test results, it was found that tunnel deformation was the largest one when the excavation of joints located closer to the tunnel crown or invert. Stability of the slope and the tunnel were varied in a certain excavation stage related to the angle of slope. In the future, based on results of this study the reinforcement method for the tunnel and slope safety in a jointed rock mass will be demonstrated.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.101-108
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• 2024

A system with the ability to recognize potential key blocks during tunnel construction by analyzing the rock face was developed in this study. This system predicts the formation of key blocks in advance and evaluates their safety factors. A laser scanner was used to collect a three-dimensional point cloud of the rock face, which was then utilized to model the excavation surface and derive the joint surfaces. Because joint surfaces have specific strikes and dip angles, the key blocks formed by these surfaces are deduced through iterative calculations, and the safety factor of each key block can be calculated accordingly. The model experiments confirmed the accuracy of the system's output in terms of the joint surface characteristics. By inputting the joint surface information, the calculated safety factors were compared with those from the existing commercial software, demonstrating stable calculation results within a 1% error margin.

• Steel and Composite Structures
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• v.21 no.5
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Journal of the Korean Geotechnical Society
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• v.30 no.9
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• pp.41-55
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• 2014

In performing seismic analysis of tunnels, it is a common practice to ignore the rock joints and to assume that the rock mass surrounding the tunnel is continuous. The applicability of this assumption has not yet been validated in detail. This study performs a series of pseudo-static discrete element analyses to evaluate the effect of rock joint on the seismic response of tunnels. The parameters considered are joint intersection location, joint spacing, joint stiffness, joint dip, and interface stiffness. The results show that the joint stiffness has the most critical influence on the tunnel response. The tunnel response increases with the spacing, resulting in localized concentration of moment and shear stress. The response of the tunnel is the lowest for joints dipping at $45^{\circ}$. This is because large shear stresses result in rotation of the principal planes by $45^{\circ}$. In summary, the weathered and smooth, vertical or horizontal, and widely spaced joint set will significantly increase the tunnel response under seismic loading. The tunnel linings are shown to be most susceptible to damage due to induced shear stress, and therefore should be checked in the seismic design.

• Economic and Environmental Geology
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• v.33 no.1
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• pp.51-59
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• 2000

As a part of natural hazard assessment, regional slope stability analysis was conducted using Geoscientific Information System (GIS) in the northern area of Chungju Lake. Selected factors which affect the slope stability in the study area were lithology, soil, density of lineament, groundwater level, dip of slope, aspect of slope, and geological engineering properties. Geological structural domains were determined by collected data of joint orientation from about 200 sites in order to produce a slope instability map. Potential type of failure and its direction could be expected through the domains. And a slope instability map was produced, comparing the representative orientations of the domains with the orientations of the slopes which were made through TIN module in ARC/INFO. Under the consideration of environmental geological characteristics of the study area, rating and weighting of each factor of slope stability analysis were decided and spatial analysis of regional slope stability was couducted through overlaying technique of GIS. The result of areal distribution of slope stability showed that the most unstable area was the area between Mt. Pudae and Mt. Jubong, and the northern area of the railway station, Samtan.