Measurement of Bangudae Rock Joint Using Non-adhesive, Non-contact Inclinometer Slope Laser Measuring System

Daegokcheon Stream in Daegok-ri, Ulju-gun, is an area with a developed valley and bedrock from Gajisan Provincial Park to the confluence of the Taehwa River across the Yangsan Fault. To measure the rock of Bangudae petroglyphs, the mineralogical weathering, joints, and scours or cavities at the bottom were confirmed. The measurement was carried out for a short period of time on the joint of the bedrock on which the Bangudae petroglyphs were engraved. Compared to the measured value obtained using existing optical fiber (Ch4 150 µm), a displacement value of 300 µm was obtained using the non-attached, non-contact type of measuring instrument. In the future, it is inferred that this instrument could be used for various cultural properties if the HSV-value suitable for illuminance and various measurement experiences are stored.

Quantification of Fracture Roughness by Change Probabilities and Hurst Exponents

The objective of the current study is to utilize an innovative method called “change probabilities” for describing fracture roughness. In order to detect and visualize anisotropy of rock joint surfaces, the roughness of one-dimensional profiles taken in different directions is quantified. The central quantifiers, change probabilities, are based on counting monotonic changes in discretizations of a profile. These probabilities, which usually vary with the scale, can be reinterpreted as scale-dependent Hurst exponents. For a large class of Gaussian stochastic processes, change probabilities are shown to be directly related to the classical Hurst exponent, which generalizes a relationship known for fractional Brownian motion. While related to this classical roughness measure, the proposed method is more generally applicable, therefore increasing the flexibility of modeling and investigating surface profiles. In particular, it allows a quick and efficient visualization and detection of roughness anisotropy and scale dependence of roughness.

Effect of Joint Characteristics and Geometries on Tunnel-Type Anchorage for Suspension Bridge

In this study, the pull-out behavior of a tunnel-type anchorage was examined by considering both geometric and rock joint characteristics. Three-dimensional finite element analyses were performed with reference to the tunnel-type anchorage cases designed and constructed in Korea. The factors influencing the anchorage response were analyzed: the enlarged part, anchorage spacing, joint orientation, spacing, and the shear strength of the rock joints. According to the numerical studies, the size of the enlarged part influenced the failure shape of the tunnel-type anchorage. It was found that the anchorage spacing, the relationship between the tunnel-type anchorage, and the joint orientation and spacing greatly influenced the pull-out behavior of the anchorage. Additionally, the friction angle had a larger impact on the anchorage’s pull-out resistance than the cohesion between the rock joints.

Combined Field and Structure from Motion Survey to Identify Rock Discontinuity Sets of Aa Shallow Rockslide

The present work shows the results of a combined field and Structure from Motion (SfM) survey performed on the detachment surface of a shallow rockslide that occurred in the Rosandra Valley (Trieste, NE Italy), which was aimed at testing the use of 3D models obtained from Remote Sensing (RS) techniques to identify joint sets affecting unstable rock masses. According to discontinuity orientation data acquired from the field (N = 223), the investigated rock mass is affected by at least nine joint sets characterised by a notable variability. The extraction of joint sets from the 3D point cloud representing the surveyed rock outcrop was strongly sensitive to the point cloud density and the values of the controlling parameters of the density function embedded within the discontinuity extractor. This work demonstrates that, in order to properly identify rock joint sets, the exclusive application of a RS approach cannot fully substitute the traditional field survey, and the estimation of discontinuity sets should be integrated with joint orientation data acquired using a geological compass. To maximise its capabilities, the semi-automatic discontinuity set extraction from 3D point clouds should always be supported by a significant statistical sample of joint orientation measurements that are preliminarily collected from the field.

Influences of Roughness Sampling Interval and Anisotropy on Shear Failure Mechanism of Rock Joint Surface

Roughness is an important factor affecting the engineering stability of jointed rock masses. The existing roughness evaluation methods are all based on a uniform sampling interval, which changes the geometrical morphology of the original profile and inevitably ignores the influence of secondary fluctuations on the roughness. Based on the point cloud data obtained by 3D laser scanning, a non-equal interval sampling method and an equation for determining the sampling frequency on the roughness profile are proposed. The results show that the non-equal interval sampling method can successfully maintain the morphological characteristics of the original profile and reduce the data processing cost. Additionally, direct shear tests under constant normal load (CNL) conditions are carried out to study the influence of roughness anisotropy on the shear failure mechanism of joint surfaces. It is found that with the increase in shear displacement, the variations in the shear stress are related to the failure mechanisms of dilatancy and shear fracture of the joint. Finally, the distributions of shear stress, dilatancy and fracture areas on the rough joint in different shear directions are calculated theoretically. Results show that the anisotropy and failure mechanism of rough joint can be well characterized by the modified root mean square parameter Z2′.