Full-Waveform Terrestrial Laser Scanning for Extracting a High-Resolution 3D Topographic Model: a Case Study on an Area of Archaeological Significance

This paper describes a method, which uses full-waveform terrestrial laser scanning to survey the surface of the slope below the Temple of Juno, located in the Valley of the Temples in Agrigento (Sicily, Southern Italy). The surface is characterized by the presence of large rock blocks, which have fallen down from the upper side; possible further detachments of rock blocks would cause a situation of general instability, with a very high risk to the archaeological structures in the near future. The methodology was designed to evaluate the potential of full-waveform laser scanning technology for the production of a very high resolution 3D topographic model of the slope, to be used as a support for the interpretation of geomorphological processes and for geotechnical analysis

Geostructural stability assessment of cave using rock surface discontinuity extracted from terrestrial laser scanning point cloud

© 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences The use of terrestrial laser scanning (TLS) in the caves has been growing drastically over the last decade. However, TLS application to cave stability assessment has not received much attention of researchers. This study attempted to utilize rock surface orientations obtained from TLS point cloud collected along cave passages to (1) investigate the influence of rock geostructure on cave passage development, and (2) assess cave stability by determining areas susceptible to different failure types. The TLS point cloud was divided into six parts (Entry hall, Chamber, Main hall, Shaft 1, Shaft 2 and Shaft 3), each representing different segments of the cave passages. Furthermore, the surface orientation information was extracted and grouped into surface discontinuity joint sets. The computed global mean and best–fit planes of the entire cave show that the outcrop dips 290° with a major north-south strike. But at individual level, the passages with dip angle between 26° and 80° are featured with dip direction of 75°–322°. Kinematic tests reveal the potential for various failure modes of rock slope. Our findings show that toppling is the dominant failure type accounting for high-risk rockfall in the cave, with probabilities of 75.26%, 43.07% and 24.82% in the Entry hall, Main hall and Shaft 2, respectively. Unlike Shaft 2 characterized by high risk of the three failure types (32.49%, 24.82% and 50%), the chamber and Shaft 3 passages are not suffering from slope failure. The results also show that the characteristics of rock geostructure considerably influence the development of the cave passages, and four sections of the cave are susceptible to different slope failure types, at varying degrees of risk

Recent Advances in Terrestrial Lidar Applications in Geotechnical Earthquake Engineering

During the past five years, geotechnical earthquake engineering and ground deformation research has benefited from the advent of terrestrial LIDAR technology, a revolutionary tool for characterizing fine-scale changes in topography. For ground deformation research, LIDAR is particularly useful for characterizing the dimensions of failures and for monitoring subtle deformations through time. Tripod mounted LIDAR systems have accuracies of approximately 0.4-2.0 cm, and can illuminate targets up to one kilometer away from the sensor. During several minutes of LIDAR scanning, millions of survey position points are collected and processed into an ultra-high resolution terrain model. During earthquake reconnaissance efforts, the detailed failure morphologies of landslides and liquefaction sites can be measured remotely and in a way that is either impractical or impossible by conventional survey means. The ultra-high resolution imagery of the complex surface morphology of ground failures allows the exploration and visualization of damage on a computer in orientations and scales not previously possible. Detailed understanding of the ground surface morphology allows for better numerical modeling of potential failure modes, deformation patterns, and morphologies. Finally, LIDAR allows for the permanent archiving of 3-D terrain models. In this paper, we present the evaluation of the accuracy, bias and dispersion of LIDAR data under controlled experimental conditions. Field applications of LIDAR-damage visualization and analysis are presented from data gathered during the 2004 Niigata Chuetsu (M6.6) earthquake and the 2007-2008 PARI-Ishikari, Hokkaido blast-liquefaction experiment

APPLICATION OF A HAZARD RATING SYSTEM FOR ROCK SLOPES ALONG A TRANSPORTATION CORRIDOR USING REMOTE SENSING

Rockfall hazards are a significant and ongoing threat to infrastructure located within steep terrain. Assessing the relative hazard along a transportation corridor is important in determining the likely location and mode of rock slope failure. Understanding where to focus attention and funds is vital for the infrastructure agencies because of the high cost of implementing preventative measures for long lengths of infrastructure. Hazard analysis has historically relied upon experienced field engineers assessing each site, which is not time or cost effective. This study focuses on using remote sensing techniques to analyze rock slopes along transportation corridors. A case study from Southern Nevada is presented with several failing rock slopes along a railroad line. The analysis uses Digital Elevation Models (DEMs), ortho-photos, and high resolution remote sensing data to analyze individual rock slopes with a risk of failure. The rockfall hazard is measured using the Rockfall Hazard Rating System (RHRS) method, while the rock mass strength is measured using the Slope Mass Rating (SMR) method. A workflow is developed that can be immediately implemented by transportation agencies for use in maintenance programs

UAV-BASED GEOTECHNICAL MODELING AND MAPPING OF AN INACCESSIBLE UNDERGROUND SITE

Digital photogrammetry is becoming a more common method used for mapping geological and structural rock mass features in underground mining. The issue of capturing geological and structural data in inaccessible, unsupported areas of mines remains even when utilizing terrestrial photogrammetric methods; thus, geotechnical models of mines are left with incomplete datasets. Large unsupported underground voids, like stopes, have the potential to cause major failures, but by filling in the geotechnical data gaps in inaccessible areas, potential failures can be predicted through kinematic analysis of the area’s mapped discontinuities. Implementation of Unmanned Aerial Vehicles (UAVs) in underground mines and recent advances in obstacle detection systems have allowed for greater experimentation with photogrammetry conducted from a UAV platform in mines. For this study, a UAV-based underground photogrammetry system was developed to manually capture imagery in an inaccessible stope at Barrick Gold Corporation’s Golden Sunlight Mine (GSM) in Whitehall, Montana, to see whether or not the approach is a viable remote sensing technique for gathering georeferenced geotechnical data. Development of the system involved selecting an appropriate UAV platform, identifying a lighting system capable of providing adequate illumination, acquiring a sensor system that consistently avoids obstacles, and choosing the appropriate UAV camera (and its respective settings) for underground UAV-based imaging. In order to georeference the data collected in the inaccessible stope, paintballs were shot into the stope to create ground control points that were then surveyed in laser range detection. These paintball marks had to be in visual line-of-sight and visible in the imagery captured via UAV camera in order to georeferenced them. Using the imagery collected in the stope at GSM, models were constructed and structural features were mapped on those models. Bentley ContextCapture software was able to successfully construct a stope model from the video frame imagery collected via UAV in the stope, while ADAM Technology was not. Split-Engineering’s Split-FX and ADAM Technology were used separately to map the discontinuity planes present within the model. A comparison of underground discontinuity mapping was performed using the UAV-based photogrammetry captured in the stope and hand mapping data collected around the entrance to the stope. It was found that northeasterly striking discontinuity planes were identified using the digital mapping, but not in hand mapping. Using UAV-based photogrammetry for geotechnical data collection creates a quick and thorough mapping process with time-stamped imagery that can potentially create a safer mine. The lessons learned during this study may help guide future efforts using UAVs to capture geologic data and to help monitor stability in areas that are inaccessible

Engineering geological 3D modeling and geotechnical characterization in the framework of technical rules for geotechnical design: the case study of the Nola’s logistic plant (southern Italy)

model is an essential step to optimize costs of the construction and limit risks from failure or damage due to unforeseen ground conditions. The modeling of ground conditions is a challenging issue to be tackled especially in the case of geological units with complex geometries and spatially variable geotechnical properties. In such a direction, coupled geological and geotechnical criteria are usually adopted to define engineering geological units. These concepts are considered by the current technical rules for geotechnical design such as the Eurocode 7 and in the national regulations which have followed it, known in Italy as “Norme Tecniche per le Costruzioni (NTC).” Notwithstanding this advanced regulatory framework, no comprehensive indications on methodological approaches were given for the 3D engineering geological modeling and geotechnical characterization of a design and construction site. In this paper, the case study of the highly heterogeneous and heteropic pyroclastic-alluvial stratigraphic setting of the Nola plain (Campania, southern Italy) characterizing the site of the Nola’s logistic plant is dealt with. The approaches are based on the engineering geological modeling analysis of a high number of stratigraphic, laboratory and in situ geotechnical data, collected for the design of the plant, and the use of a specialized modeling software providing advanced capabilities in spatial modeling of geological and geotechnical information, as well as in their visual representation. The results obtained, including also the analysis of statistical variability of geotechnical properties and the identification of representative geotechnical values, can be potentially considered a methodological approach, consistent with the current technical rules for geotechnical design as well as with fundamental concepts of engineering geological modeling and mapping

Methodology Applied to the Diagnosis and Monitoring of Dikes and Dams

International audienc

3D modelling of the dolerite dyke network within the Siilinjärvi phosphate deposit

Non peer reviewe

NADIR AND OBLIQUE UAV PHOTOGRAMMETRY TECHNIQUES FOR QUANTITATIVE ROCK FALL EVALUATION IN THE RIMROCKS OF SOUTH-CENTRAL MONTANA

As our cities expand into geologically sensitive areas across the greater Rocky Mountain region and beyond, quantitative methods of assessment are increasingly critical for the development of evidence-based alternatives to avoid or mitigate geologic hazards. Unmanned Aerial Vehicle (UAV) photogrammetry can improve these geologic investigations by enabling remote visual inspection, measurement, and spatial analysis while eliminating many of the physical access limitations that contribute to field sampling bias and human error. UAV photogrammetry technology was employed to evaluate fragmental rock fall hazards at two locations in the Rimrocks region of south-central Montana, Zimmerman Trail Road and Phipps Park. At these sites, active retrogressive rock slope instability caused by differential erosion has produced damaging rock fall. Nadir and oblique imagery of the 35-acre Zimmerman Trail Road and 13-acre Phipps Park study areas was acquired with a DJI Phantom 4 Pro UAV and processed into digital photogrammetry with Pix4Dmapper. Remote methods of analysis were employed to measure the orientation of discontinuities in rock fall source areas and to quantify rock fall susceptibility. At Zimmerman Trail Road, photogrammetry data products were used to numerically differentiate rock fall hazard zones along the 0.3-mile long rock slope in accordance with the detailed Rock Fall Hazard Rating System (Pierson, 1991). At Phipps Park, photogrammetry was used to measure the size, run out distance, and change in elevation of high energy rock fall and to generate 2D and 3D slope profiles, which were used to model potential future rock fall. The methods and findings demonstrate how nadir and oblique UAV photogrammetry can be used to implement quantitative, defensible approaches for evaluating rock fall susceptibility and run out potential in geologic investigations of fragmental rock fall hazard areas