Comparing traditional geomechanical and remote sensing techniques for rock mass characterization 

2021 ◽  
Author(s):  
Angela Caccia ◽  
Biagio Palma ◽  
Mario Parise
Keyword(s):  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Quantitative Description ◽  
Present Contribution ◽  
Rock Mass Characterization ◽  
Rock Face ◽  
Remote Sensing Techniques ◽  
The Stability ◽  
Processing Techniques

<p>Analysis of the stability conditions of rock masses starts from detailed geo-structural surveys based on a systematic and quantitative description of the systems of discontinuities. Traditionally, these surveys are performed by implementing the classical geomechanical systems, available in the scientific literature since several decades, through the use of simple tools such as the geological compass to measure dip and dip direction directly on the discontinuity systems, and to fully describe their more significant physical characteristics (length, spacing, roughness, persistence, aperture, filling, termination, etc.). In several cases, this can be difficult because the discontinuities, or even the rock face, cannot be easily accessible. To have a complete survey, very often the involvement of geologists climbers is required, but in many situations this work is not easy to carry out, and in any case it does not cover the whole rock front.</p><p>Today, to solve these problems, traditional geomechanical surveying is implemented by innovative remote techniques using, individually or in combination, instruments such as terrestrial laser scanners and unmanned aerial vehicles to build a point cloud.</p><p>This latter permits to extract very accurate data on discontinuities for stability analyses, based on areal and non-point observations. In addition, the point cloud allows to map sub-vertical walls in their entirety in much shorter times than traditional surveying.</p><p>At this regard, two rock slopes were detected in the Sorrento Peninsula (Campania, southern Italy) with techniques that include traditional mapping, dictated by the guidelines of the International Society for Rock Mechanics, and the remote survey, through laser scanning and drone photogrammetry. The data obtained were processed automatically and manually through the Dips, CloudCompare and Discontinuity Set Extractor softwares.</p><p>In the present contribution we highlight the limits and advantages of the main data collection and the processing techniques, and provide an evaluation of the software packages currently available for the analysis and evaluation of discontinuities, in order to obtain a better characterization of the rock mass.</p>

scholarly journals Comparison of Remote Sensing Techniques for Geostructural Analysis and Cliff Monitoring in Coastal Areas of High Tourist Attraction: The Case Study of Polignano a Mare (Southern Italy)

2021 ◽  
Vol 13 (24) ◽  
pp. 5045
Author(s):  
Lidia Loiotine ◽  
Gioacchino Francesco Andriani ◽  
Michel Jaboyedoff ◽  
Mario Parise ◽  
Marc-Henri Derron
Keyword(s):  
Remote Sensing ◽  
Rock Mass ◽  
Urban Areas ◽  
Laser Scanning ◽  
Rock Slope ◽  
Mitigation Measures ◽  
Tourist Attraction ◽  
Field Surveys ◽  
Rock Mass Characterization ◽  
Remote Sensing Techniques

Rock slope failures in urban areas may represent a serious hazard for human life, as well as private and public property, even on the occasion of sporadic episodes. Prevention and mitigation measures indispensably require a proper rock mass characterization, which is often achieved by means of time-consuming, costly and dangerous field surveys. In the last decades, remote sensing devices such as high-resolution digital cameras, laser scanners and drones have been widely used as supplementary techniques for rock slope analysis and monitoring, especially in poorly accessible areas, or in sites of large extension. Although several methods for rock mass characterization by means of remote sensing techniques have been reported in specific studies, there are very few contributions that focused on comparing the different methods in an attempt to establish their advantages and limitations. With this study, we performed digital photogrammetry, Terrestrial Laser Scanning and Unmanned Aerial Vehicle surveys on a cliff located in a popular tourist attraction site, characterized by complex geological and geomorphological settings, as well as by disturbance elements such as vegetation and human activities. For each point cloud, we applied geostructural analysis by means of semi-automatic methods, and then compared multi-temporal acquisitions for cliff monitoring. By quantitative comparison of the results and validation by means of conventional geostructural field surveys, the pros and cons of each method were outlined in attempt to depict the conditions and goals the different techniques seem to be more suitable for.

Geomechanical characterization of rock masses by means of remote sensing techniques

2020 ◽  
Author(s):  
Lidia Loiotine ◽  
Marco La Salandra ◽  
Gioacchino Francesco Andriani ◽  
Giovanni Barracane ◽  
Marc-Henri Derron ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Mitigation Measures ◽  
Rock Masses ◽  
Testing Procedures ◽  
Remote Sensing Techniques

<p>Improving the methods for the characterization of rock masses by integrating traditional field surveys with remote sensing techniques is fundamental for practical and realistic discontinuous modelling, in order to identify the failures and kinematics, develop landslide susceptibility assessment and plan prevention and mitigation measures.</p><p>A 20 m-high cliff at Polignano a Mare (Southern Italy) was selected as case study for the presence of well-developed discontinuities (bedding and joints) and due to the local morphology, consisting of a valley with opposite slopes at a distance of 150 m, and a pocket beach at their toe. This configuration allowed to perform both traditional and remote sensing surveys. First, photogrammetry methods were carried out on the ground and with the help of a boat. Structure from Motion (SfM) technique was then used to process and combine the pictures, in order to elaborate a raw point cloud of the case study. Secondly, high resolution Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle (UAV) techniques were conducted after positioning Ground Control Points (GCPs) all over the rock mass, with the aim of obtaining a more detailed point cloud. Eventually, a unique and optimized georeferenced point cloud was obtained by combining the previous models, also removing the non-geological objects. Furthermore, Infrared Thermography (IT) was carried out in order to investigate the fracture pattern, the areas of concentrated stress, and the presence of humidity and voids.</p><p>The structural analysis of the rock mass was performed directly on the point cloud, by testing procedures and algorithms for the automatic identification of discontinuity sets and of their orientation, spacing, persistence and roughness.</p><p>The next step of this research will concern the evaluation of the instability mechanisms with the help of kinematic analyses, by means of stereographic projections. Finally, the reliability of the procedure for a complete rock mass characterization, which is expected to be obtained as the final result, will be tested by means of numerical stability solutions, after calibrating the geomechanical model and importing the fracture system in an appropriate software.</p><p> </p>

scholarly journals Exploiting a Semi-Automatic Point Cloud Segmentation Method to Improve the Quality of Rock-Mass Characterization. The Cima Grappa Conservative Restoration Case Study

2021 ◽  
Vol 10 (5) ◽  
pp. 276
Author(s):  
Francesco Mugnai ◽  
Paolo Farina ◽  
Grazia Tucci
Keyword(s):  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Automatic Segmentation ◽  
Point Clouds ◽  
Segmentation Method ◽  
Rock Mass Characterization ◽  
Point Cloud Segmentation ◽  
Conservative Restoration ◽  
The Military

This paper presents results from applying semi-automatic point cloud segmentation methods in the underground tunnels within the Military Shrine’s conservative restoration project in Cima Grappa (Italy). The studied area, which has a predominant underground development distributed in a network of tunnels, is characterized by diffuse rock collapsing. In such a context, carrying out surveys and other technical operations are dangerous activities. Considering safety restrictions and unreachable impervious tunnels, having approached the study area with the scan-line survey technique resulted in only partial rock mass characterization. Hence, the geo-mechanical dataset was integrated, applying a semi-automatic segmentation method to the point clouds acquired through terrestrial laser scanning (TLS). The combined approach allowed for remote performance of detailed rock mass characterization, even remotely, in a short time and with a limited operators presence on site. Moreover, it permitted extending assessing tunnels’ stability and state of conservation to the inaccessible areas.

scholarly journals 3D COMPARISON TOWARDS A COMPREHENSIVE ANALYSIS OF A BUILDING IN CULTURAL HERITAGE

2018 ◽  
Vol XLII-2 ◽  
pp. 1061-1066 ◽  
Author(s):  
I. Selvaggi ◽  
M. Dellapasqua ◽  
F. Franci ◽  
A. Spangher ◽  
D. Visintini ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Point Cloud ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Deformation Analysis ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Site Restoration ◽  
Close Range ◽  
Remote Sensing Techniques

Terrestrial remote sensing techniques, including both Terrestrial Laser Scanning (TLS) and Close-Range Photogrammetry (CRP), have been recently used in multiple applications and projects with particular reference to the documentation/inspection of a wide variety of Cultural Heritage structures.<br> The high density of TLS point cloud data allows to perform structure survey in an unprecedented level of detail, providing a direct solution for the digital three-dimensional modelling, the site restoration and the analysis of the structural conditions. Textural information provided by CRP can be used for the photorealistic representation of the surveyed structure. With respect to many studies, the combination of TLS and CRP techniques produces the best results for Cultural Heritage documentation purposes. Moreover, TLS and CRP point cloud data have been proved to be useful in the field of deformation analysis and structural health monitoring. They can be the input data for the Finite Element Method (FEM), providing some prior knowledge concerning the material and the boundary conditions such as constraints and loading.<br> The paper investigates the capabilities and advantages of TLS and CRP data integration for the three-dimensional modelling compared to a simplified geometric reconstruction. This work presents some results concerning the Baptistery of Aquileia in Italy, characterized by an octagonal plan and walls composed by masonry stones with good texture.

scholarly journals Rock Mass Characterization by UAV and Close-Range Photogrammetry: A Multiscale Approach Applied along the Vallone dell’Elva Road (Italy)

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 436
Author(s):  
Maria Migliazza ◽  
Maria Teresa Carriero ◽  
Andrea Lingua ◽  
Emanuele Pontoglio ◽  
Claudio Scavia
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Small Scale ◽  
Stability Conditions ◽  
Multiscale Approach ◽  
Rock Mass Characterization ◽  
Geometrical Data ◽  
Close Range ◽  
The Stability ◽  
Kinematic Mechanisms

Geostructural rock mass surveys and the collection of data related to discontinues provide the basis for the characterization of rock masses and the study of their stability conditions. This paper describes a multiscale approach that was carried out using both non-contact techniques and traditional support techniques to survey certain geometrical features of discontinuities, such as their orientation, spacing, and useful persistence. This information is useful in identifying the possible kinematics and stability conditions. These techniques are extremely useful in the case study of the Elva valley road (Northern Italy), in which instability phenomena are spread across 9 km in an overhanging rocky mass. A multiscale approach was applied, obtaining digital surface models (DSMs) at three different scales: large-scale DSM of the entire road, a medium-scale DSM to assess portions of the slope, and a small-scale DSM to assess single discontinuities. The georeferenced point cloud and consequent DSMs of the slopes were obtained using an unmanned aerial vehicle (UAV) and terrestrial photogrammetric technique, allowing topographic and rapid traditional geostructural surveys. This technique allowed us to take measurements along the entire road, obtaining geometrical data for the discontinuities that are statistically representative of the rock mass and useful in defining the possible kinematic mechanisms and volumes of potentially detachable blocks. The main purpose of this study was to analyse how the geostructural features of a rock mass can affect the stability slope conditions at different scales in order to identify road sectors susceptible to different potential failure mechanisms using only kinematic analysis.

scholarly journals Tomographic Experiments for Defining the 3D Velocity Model of an Unstable Rock Slope to Support Microseismic Event Interpretation

Geosciences ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 327
Author(s):  
Zhiyong Zhang ◽  
Diego Arosio ◽  
Azadeh Hojat ◽  
Luigi Zanzi
Keyword(s):  
Rock Mass ◽  
Velocity Distribution ◽  
Velocity Model ◽  
Microseismic Monitoring ◽  
Time Inversion ◽  
Basic Step ◽  
Rock Face ◽  
3D Velocity Model ◽  
Microseismic Events ◽  
The Stability

To monitor the stability of a mountain slope in northern Italy, microseismic monitoring technique has been used since 2013. Locating microseismic events is a basic step of this technique. We performed a seismic tomographic survey on the mountain surface above the rock face to obtain a reliable velocity distribution in the rock mass for the localization procedure. Seismic travel-time inversion showed high heterogeneity of the rock mass with strong contrast in velocity distribution. Low velocities were found at shallow depth on the top of the rock cliff and intermediate velocities were observed in the most critical area of the rock face corresponding to a partially detached pillar. Using the 3D velocity model obtained from inversion, localization tests were performed based on the Equal Differential Time (EDT) localization method. The results showed hypocenter misfits to be around 15 m for the five geophones of the microseismic network and the error was significantly decreased compared to the results produced by a constant velocity model. Although the localization errors are relatively large, the accuracy is sufficient to distinguish microseismic events occurring in the most critical zone of the monitored rock mass from microseismic events generated far away. Thus, the 3D velocity model will be used in future studies to improve the classification of the recorded events.

Automatic extraction of rock mass discontinuity based on 3D laser scanning

2020 ◽  
Vol 54 (1) ◽  
pp. qjegh2020-054
Author(s):  
Na Chen ◽  
Xiaoming Cai ◽  
Shu Li ◽  
Xiaobo Zhang ◽  
Qinghui Jiang
Keyword(s):  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Reproducible Research ◽  
Normal Vector ◽  
Automatic Extraction ◽  
Cloud Data ◽  
Plane Extraction ◽  
Data Source ◽  
Ransac Algorithm

Discontinuity information is important in evaluating the security of a rock mass for the distribution of discontinuity spacings, which affects the mechanical properties and stability of the rock mass. Numerous studies have been conducted on the semi-automatic or automatic extraction of discontinuities from point cloud data. We developed a random sample consensus discontinuity detection (RANSAC) method to automatically extract discontinuities in a rock mass. The proposed method is entirely based on a raw point instead of a triangular mesh, which can retain the integrity of the data. A modified RANSAC algorithm is used to increase the degree of automation. The proposed approach consists of four steps: (1) calculation of the normal vector of the point cloud; (2) plane extraction using the modified RANSAC algorithm; (3) delineation of the boundary of the discontinuity using the modified Graham scan algorithm; and (4) calculation of the orientation and area on the basis of the normal vector and the boundary of the discontinuity. The results and the raw data source are freely provided for reproducible research and to develop the method further.

scholarly journals LASER SCANNING AND POINT CLOUD SEGMENTATION FOR CONTACTLESS GEO-MECHANICAL SURVEYING: CONSERVATIVE RESTORATION IN HYPOGEUM ENVIRONMENT

2021 ◽  
Vol XLVI-M-1-2021 ◽  
pp. 455-461
Author(s):  
F. Mugnai
Keyword(s):  
Rock Mass ◽  
Point Cloud ◽  
Laser Scanning ◽  
Coating Materials ◽  
Point Cloud Segmentation ◽  
Survey Technique ◽  
Advanced Analysis ◽  
Scan Line ◽  
Conservative Restoration ◽  
The Military

Abstract. The work presents a survey campaign specifically designed to formulate an effective restoration project in a Cultural Heritage context, the Military Shrine in Cima Grappa (Italy). Several outputs have been generated by exploring the most advanced laser scanning survey technique and some specific point cloud analysis algorithms. A detailed geometrical 3D reconstruction of human-made and natural tunnels coating materials, a geo-mechanical survey of the rock mass, a map of rock collapses and cinematic analysis of instability processes.Integrating Laser Scanning technique with the Scan-line survey allowed to perform advanced analysis and rock-mass characterisation in a predominant subterranean developed area. Most of the tunnels and underground spaces displayed rock collapses and diffuse active instability processes that certainly could have drastically slowed down surveys and analysis. The adopted techniques allowed both to proceed in acquiring data end in delivering sound outputs rapidly.

scholarly journals INTEGRATING LASER SCANNING AND GEO-MECHANICAL SURVEY IN CONSERVATIVE RESTORATION; THE CASE OF FIRST WORLD WAR’S CIMA GRAPPA MILITARY SHRINE, ITALY.

2021 ◽  
Author(s):  
Francesco Mugnai ◽  
Paolo Farina ◽  
Grazia Tucci
Keyword(s):  
Rock Mass ◽  
Laser Scanning ◽  
General Description ◽  
Coating Materials ◽  
Restoration Project ◽  
Rock Mass Characterization ◽  
The One ◽  
Conservative Restoration ◽  
The Military ◽  
First World

The work presents results obtained performing a survey campaign specifically designed to formulate an effective restoration project in a critical context. Within the remarkable project, promoted and financed by the Italian Presidency of the Council of the Ministers, and the Italian Ministry of Defence, for designing the conservative restoration plan of the Military Shrine in Cima Grappa (Italy), the assessment of the overall tunnels’ stability and a report of the state of conservation of the underground area has been produced. Exploiting the most advanced laser scanning survey technique, and some specific algorithms for point cloud analysis, several outputs have been generated, in particular a detailed geometrical 3D reconstructions of man-made and natural tunnels coating materials, geo-mechanical survey of rock mass, map of rock collapses and cinematic analysis of instability processes. The integration of Laser Scanning technique with the most commonly used Scan-line survey for rock-mass characterization and architectural surveys, allowed to perform advances analysis even in a high-risk study area as the one considered in the restoration project, which is represented by a predominant subterranean development. Most of the tunnels and underground spaces, displayed rock collapses and diffuse active instability processes that certainly could have drastically slowed down surveys and analysis. The adopted techniques allowed to rapidly proceed in acquiring data end to deliver sound outputs. This paper aims to report both a general description of the project, spending some words on the historical value of the place and describing the complex environment of work, and a detailed depiction of the performed survey activities with particular attention in showing laser scanning survey and the obtained results.

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