Joint Orientation Measurements Research Articles

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.

3D Laser Scanner를 이용한 암반사면의 절리방향 측정의 신뢰성에 관한 연구

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 ±4° of dip and ±5° of dip direction. Generally, the method of clinometer has ±5° and ±10° 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.

Joint orientation measurements in Western Alberta and British Columbia

Joint orientations were measured in the mountains of Western Albertaand British Columbia. These were then evaluated statistically accordingto the standard method of Kohlbeck and Scheidegger. If the bisectricesof the preferred joint orientations are interpreted as principal directionsof the neotectonic stress field, the maximum compression in the latteris found to be from NE-SW (in the South) to NNE-SSW (in the North).This agrees well with data regarding the neotectonic intraplate stressesobserved from oil-well break-out data.

A Landsat TM Structural Interpretation of the South Munster Basin, Co. Cork

The paper presents a structural interpretation of Landsat thematic-mapper imagery covering the South Munster Basin, carried out at 1:50,000 scale. The basin can be subdivided into four broadly N-S zones on the basis of the dominant lineation trends shown by rose diagrams of the fracture linears for each 10km x 10km square on the map. Comparison with field-derived fracture data reveals that, although the same fracture orientations are present in the data sets, there are marked differences in emphasis between them. These differences are thought to reflect a difference in scale of structures recorded by the two processes, together with a lack of joint-orientation measurements in the field-based data set. A number of major strike-oriented zones with closely spaced fractures are recognised, notably the ENE- or NE-oriented zones extending eastward from Bantry and Dunmanus bays and on the west side of Cork Harbour. The Glandore High, an area of reduced Dinantian stratigraphic thickness and regional structural culmination, is coincident with one of the N-S zones defined on the rose diagram map and may extend farther north than previously proposed. However, there is no clear expression of the important Cork-Kenmare facies line on the imagery.

A Landsat Tm Structural Interpretation of the South Munster Basin, Co. Cork

The paper presents a structural interpretation of Landsat thematic-mapper imagery covering the South Munster Basin, carried out at 1:50,000 scale. The basin can be subdivided into four broadly N-S zones on the basis of the dominant lineation trends shown by rose diagrams of the fracture linears for each 10km x 10km square on the map. Comparison with field-derived fracture data reveals that, although the same fracture orientations are present in the data sets, there are marked differences in emphasis between them. These differences are thought to reflect a difference in scale of structures recorded by the two processes, together with a lack of joint-orientation measurements in the field-based data set. A number of major strike-oriented zones with closely spaced fractures are recognised, notably the ENEor NE-oriented zones extending eastward from Bantry and Dunmanus bays and on the west side of Cork Harbour. The Glandore High, an area of reduced Dinantian stratigraphic thickness and regional structural culmination, is coincident with one of the N-S zones defined on the rose diagram map and may extend farther north than previously proposed. However, there is no clear expression of the important Cork-Kenmare facies line on the imagery.

A Landsat TM Structural Interpretation of the South Munster Basin, Co. Cork

The paper presents a structural interpretation of Landsat thematic-mapper imagery covering the South Munster Basin, carried out at 1:50,000 scale. The basin can be subdivided into four broadly N-S zones on the basis of the dominant lineation trends shown by rose diagrams of the fracture linears for each 10km x 10km square on the map. Comparison with field-derived fracture data reveals that, although the same fracture orientations are present in the data sets, there are marked differences in emphasis between them. These differences are thought to reflect a difference in scale of structures recorded by the two processes, together with a lack of joint-orientation measurements in the field-based data set. A number of major strike-oriented zones with closely spaced fractures are recognised, notably the ENE- or NE-oriented zones extending eastward from Bantry and Dunmanus bays and on the west side of Cork Harbour. The Glandore High, an area of reduced Dinantian stratigraphic thickness and regional structural culmination, is coincident with one of the N-S zones defined on the rose diagram map and may extend farther north than previously proposed. However, there is no clear expression of the important Cork-Kenmare facies line on the imagery.

Orthogonal joint systems in the Bergen area, southwest Norway, and their regional significance

Joint orientation measurements are reported from the Bergen district, southwest Norway. The prevailing joint systems form two near-vertical, near-orthogonal sets, striking preferentially NW-SE and NE-SW. The orientation of these fissure systems is consistent with fissure systems dissecting the surface formations (Precambrian to Quaternary) throughout Britain and northwest France. They also show general agreement with lineaments in southern Norway as revealed by Landsat imagery. It is suggested that the orthogonal joint network represents a fundamental tectonic structure, originally implanted into the mobile outer layer of the Earth in Precambrian time. The network has been repeatedly reactivated throughout the Earth's dynamic/tectonic history. It was probably formed in a shear regime caused by torsional deformation associated with rotation of large-scale ‘lithospheric’ units, which is still operating today.

Reproducibility of joint orientation measurements in rock : Ewan, V J; West, G Transport and Road Research Laboratory supplementary report 702, 1981, 18P

An investigation has been made into the reproducibility of measurement of joint orientation in rock. The rocks studied were sandstone, mudstone and limestone exposed in the kielder aqueduct tunnels; the same limestone exposed in a nearby quarry was also studied. It was found that for six observers measuring a 10M long scanline, the orientation of particular joints recorded can have a mean maximum variation of plus or minus 10 degrees for dip direction and plus or minus 5 degrees for dip angle without there being any real difference in the joint orientation. However, the joint orientation diagrams produced by the six observers were in broad general agreement, and allowed the major joint sets to be identified. When the effects of the observed variation were compared with the joint orientation rating adjustment in Bieniawski's rock mass classification it was seen that they were insignificant. However, the effects of variation need to be taken into account when dealing with the stability of individual blocks of rock. (Author/TRRL)

The Relationship Between Fracture Traces and Joints in a Tertiary Basin, Southwest Montana

ABSTRACTThe relationship between fracture traces mapped on aerial photographs and joints mapped in the field were examined for a synclinal basin, near Three Forks, Montana, Fracture traces mapped in the southern half of the Milligan Canyon area by stereoscopic examination of aerial photographs show a predominant east‐west and north‐south orientation.A total of 4,675 joint orientation measurements made in the field also showed predominant north‐south and east‐west orientations. The similarity suggests that mapped fracture traces reflect areas of joint and fracture concentrations in the subsurface and may be a valuable water exploration tool in Tertiary basins of Montana.

Geomechanical model of an alpine valley

Geomechanical Model of an Alpine Valley In-situ stress measurements in a near-surface tunnel at the foot of a mountain range in the Felber Valley (Austria) yielded unexpectedly high stress values which do not fit into the regional tectonic stress pattern. The anomalous orientation of principal stress the axes is confirmed by a statistical evaluation of joint-orientation measurements. Theoretical calculations of the stresses by means of a finite-element model show that the experimentally found values can be explained by the weight of the material alone as a consequence of the local topographic conditions. An essential assumption herein is that the mountain range rests on a plastic substratum so that approximately the same pressure is acting everywhere along the horizontal basis. If the mountain mass rests on a (vertically) rigid material, then the experimental stress values cannot be reproduced by the calculations. Thus, one has an indication that the rheological state of the material in the earth's crust is plastic (over geological time ranges) already at comparatively shallow depths.

On the tectonics of the Western Himalaya

The present study aims at making a contribution to the tectonics of the Western Himalayan Regions of Jammu, Kashmir and Ladakh. During the summer of 1978, the orientation of many joints has been measured in outcrops along the road from Jammuvia Srinagar to Leh. Based upon the contention that the visible rock-joints are shear surfaces produced by the neotectonic stress field, the principal stress directions of the latter can be calculated from a statistical analysis of the orientations of the joints. Furthermore, it has also been proposed that many valley trends follow tectonic shear zones. Thus, a statistical evaluation of the valley trends in Jammu and Kashmir has been made. The analysis of the orientations of joints and river valley trends has shown that, in both these features, there are two pairs of conjugate systems of directions. The first, the preponderant one, has preferred pole directions of N 55°E and N 138°E; it is produced by a principal horizontal compression with an azimuth of N 7°E. The second system is only vestigially developed in the joints, it has preferred pole-azimuths around N 92°E and N 358°E. Field evidence shows joints belonging to this second system to terminate at joints belonging to the first (preponderant) system which permits one to infer that the second system is older than the first and, thus, belongs to previous orientation of the tectonic stress field. In the valleys, both systems are almost equally well developed which indicates that earlier orientations are preserved in valleys for a longer time than in joints. The orientations of the neotectonic stress field deduced from joint-orientation measurements are in good conformity with the ideas of plate tectonics. Thus, India “pushes” (or is dragged) northward; the joints are slip surfaces fitting into this pattern.

On the theory of the evaluation of joint orientation measurements

On the theory of the evaluation of joint orientation measurements

On the theory of the evaluation of joint orientation measurements

On the Theory of the Evaluation of Joint Orientation Measurements The current procedure for the evaluation of sets of joint-orientation measurements in terms of regional stresses is critically reviewed. It is shown that the counting circles on a sphere for constructing density diagrams are not circles on an equal-area (Lambert) projection of such a sphere; the correct curves are presented. It is shown that the search for modal maxima in the density diagrams corresponds to a nonparametric statistic for which it is difficult to give confidence limits. General considerations about the statistics of experiments yield the result that 12–15 joint measurements in an outcrop are sufficient to define 3 maxima, if such maxima exist at all. In order to give confidence limits, it is best to introduce a parametric model for the distribution of joint orientations. For a single cluster of orientations the probability density function is chosen as proportional to exp (k2 cos2θ) whereθ is the polar deviation angle from the “mean” direction; since the basic joint-orientations havethree fundamental directions, three probability density functions of the above type have to be superposed. These are determined by giving 11 parameters which can be determined by a function-minimization procedure from a given set of measurements. This procedure is best carried out on a computer. In this fashion, confidence limits for the preferred joint directions can be obtained. For the determination of the stresses, only two preferred sets of joints are required reducing the necessary number of parameters to 7. According to the usual theory of the statistics of trials, it is seen that 21 measurements are required to determine them. Thus, using a parametric statistic, it is seen that 21 measurements of joint orientations in an outcrop should suffice to determine the stress field that produced them. If the sharpness of the distributions is assumed as a priori known, this reduces again to the 15 or 20 measurements required for a non-parametric evaluation.