• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.2
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• pp.3-12
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• 2001

This paper presents the proposed methods of DE (distinct element) modelling to estimate the stability of tunnels in jointed rock masses. First, the criterion to select the joint set(s) contributed to the discontinuous behaviour in a tunnel section is proposed. Selected joint set(s) is(are) considered to form the edges of distinct elements (rock blocks) and the others to modify the elastic properties of rock blocks. The complex DE model with the average and the deviation of joint orientation and joint length for each joint set was compared to the simple model with only the average of joint orientation and the assumption that joint length is infinite. As a result, the latter is suitable to the purpose of tunnel design because it can show the consistent behaviour of a jointed rock mass such as the locally discontinuous failure and the global anisotropic behaviour.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.119-134
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• 1999

Joints developed around the Moryang fault were investigated by traverse and inventory methods in order to characterize their orientation, spacing and density. The results of the traverse method show that the orientation of the dominant joint sets of the study area is NNE and EW, and that joint spacing distribution is a negative exponential distribution to the center of the fault and a log-normal distribution to the margin of the fault. The results of the inventory method show that the orientation of the dominant joint sets on joint map is NW and NE, and that joint density tends to increase toward the center of the fault. Fractal dimension was determined by using Box-counting method and Cantor's dust method to quantify the distribution of joint network and to evaluate the dimension around the fault. The dimension determined by Box-counting method ranges from 1.31 to 1.70 and shows the tendency of increasing value toward the center of the fault. Comparing fractal dimension by Box-counting method with joint density, fractal dimension is directly proportional to joint density. Nevertheless, fractal dimension could be varied due to the different distribution patterns of the joints with same density. The dimensions determined by Cantor's dust method show different values with respect to the orientation of scan lines. This results form the anisotropy of joint distribution.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.392-400
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• 2013

Joint sets should be considered as an influence factor, when location of subsidence zone by stopes is predicted. And the mechanical properties and distribution patterns of joint set above stopes may be affecting subsidence occurrence. In this study, therefore, the orientation of joint sets is reanalyzed with the data from the previous research on prediction of defining the subsidence zone. From a correlated analysis, the influence of major joint set($J_1$) on subsidence location was analyzed by comparing the angle of assumption with the angle of major joint set($J_1$).

• Tunnel and Underground Space
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• v.24 no.1
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• pp.55-66
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• 2014

In this study, a joint survey system was developed to efficiently analyze geometrical characteristics of joint structures in rock mass using photogrammetric technique. The system includes both hardware and software. The hardware consists of a high resolution image camera for photographing image of a surface of rock body, a direction controlling system for adjusting the attitude of camera, and a digital compass for measuring the rotation angle of camera. The software was also developed in order to analyze the orientation, density, mean length of joints revealed on the images of rock surfaces. The software developed in this study was named as JointeXtractor. As applying this system into several field measurements, the orientation, density, mean length of joints could be quantitatively measured through analyzing the images of rock surfaces, in which the case of a difficult-to-access area was especially included for the test of the system.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.19-30
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• 2002

Rock joint orientation is one of important geometric attributes that have an influence on the stability of rock structures such as rock slopes and tunnels. Especially, statistical models of the geometric attributes of rock joints can provide a probabilistic approach of rock engineering problems. The result from probabilistic modeling relies on the choice of statistical model. Therefore, it is critical to define a representative statistical model for joint orientation data as well as joint size and intensity and build up a series of modeling procedure including analytical validation. In this paper, we have examined a theoretical methodology for the statistical estimate and hypothesis analysis based upon Fisher distribution and bivariate normal distribution. In addition, we have proposed the algorithms of random number generator which is applied to the simulation of rock joint networks and risk analysis.

• Tunnel and Underground Space
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• v.19 no.1
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• pp.1-10
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• 2009

Site characterization for structural stability in rock masses mainly involves the collection of joint property data, and in the current practice, much of this data is collected by hand directly at exposed slopes and outcrops. There are many issues with the collection of this data in the field, including issues of safety, slope access, field time, lack of data quantity, reusability of data and human bias. It is shown that information on joint orientation, spacing and roughness in rock masses, can be automatically extracted from LIDAR (light detection and ranging) point floods using the currently available Split-FX point cloud processing software, thereby reducing processing time, safety and human bias issues.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.78-83
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• 2007

The paper focuses on the establishment of optimized bucket path planning and trajectory control designated for force-reflecting backhoe reacting to excavation environment, such as potential obstacles and ground characteristics. The developed path planning method can be used for precise bucket control, and more importantly for obstacle avoidance which is directly related to safety issues. The platform of this research was based on conventional papers regarding the kinematic model of excavator. Jacobian matrix was constructed to find optimal joint angles and rotation angles of bucket from position and orientation data of excavator. By applying Newton-Raphson method optimal joint angles and bucket orientation were derived simultaneously in the way of minimizing positional errors of excavator. The model presented in this paper was intended to function as a cornerstone to build complete and advanced path planning of excavator by implementing soil mechanics and further study of excavator dynamics together.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1929-1930
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• 2006

Human like robot arm posture for grasping by considering the shape of the target object is quite a challenge in the field of robotics. In this paper, an optimized grasp posture with respect to the shape of the object considering the wrist joint angle and elbow elevation angle, in order to verify that the grasp posture is human like has been proposed. Given a target object, the candidates for grasp are computed by the method described in this paper. For each candidate, the closed loop inverse kinematics has been solved for the corresponding hand position and orientation. From the obtained joint angles through inverse kinematics, the elbow elevation angle has been computed and compared with the elbow elevation angle obtained through human movement data by the characteristic equation. After considering all the candidates, the hand position and orientation with minimum wrist joint and difference in elbow elevation angles has been utilized as the optimized grasp posture. Simulation results are presented.

• Tunnel and Underground Space
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• v.25 no.1
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• pp.97-106
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• 2015

We must precisely investigate the mechanical characters of rock to design rock slope safely and efficiently. But the method of clinometer has some disadvantages. So, we need a new measurement that can replace the method of clinometer. In this study, we analyze the reliability of joint orientation measurements in rock slope using the 3D laser scanner and program Split-FX that is a point cloud data analysis software. We could acquire the 495 pieces joint data through the automatic extraction of features. And we confirmed that there were some errors occurred with ${\pm}4^{\circ}$ of dip and ${\pm}5^{\circ}$ of dip direction. Generally, the method of clinometer has ${\pm}5^{\circ}$ and ${\pm}10^{\circ}$ error ranges of the joint orientation(dip/dip direction) that are the results of the advance research. Therefore, we analyzed the method of 3D laser scanner, and it is found to be efficient, reliable. This method is expected to mend the disadvantages of Clinometer method.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.486-494
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• 2003

When the orientations of joints are measured on a rock exposure, there are frequent cases that are difficult to approach by the surveyor to the target joints or to set up scanlines on the slope. In this study, to complement such limit and weak points, a new algorithm was developed to interpret joint orientation from analyzing the images of rock slope. As a method of arranging the multiple images of a rock slope, the multistage convergent photographing system was introduced to overcome the limitation of photographing direction which existing method such as parallel stereophotogrammetric system has and to cover the range of image measurement, which is the overlapping area between the image pair, to a maximum extent. To determine camera parameters in the perspective projection equation that are the main elements of the analysis method, a new method was developed introducing three ground control points and single ground guide point. This method could be considered to be very simple compared with other existing methods using a number of ground control points and complicated analysis process. So the global coordinates of a specific point on a rock slope could be analyzed with this new method. The orientation of a joint could be calculated using the normal vector of the joint surface which can be derived from the global coordinates of several points on the joint surface analyzed from the images.