Investigating and quantifying the uncertainty beyond the stability analysis of high unstable fractured rock cliff by Remote Piloted Aerial System (RPAS)-based Digital Photogrammetry: the example of the Gallivaggio landslide

2020 ◽  
Author(s):  
Niccolò Menegoni ◽  
Daniele Giordan ◽  
Cesare Perotti
Keyword(s):  
Stability Analysis ◽  
Numerical Models ◽  
Fractured Rock ◽  
Laser Scanner ◽  
Rock Fall ◽  
Time Saving ◽  
Mode Of Failure ◽  
Failure Event ◽  
The Stability ◽  
Unstable Rock

<p>The recent advantages in Remote Piloted Aerial System (RPAS) and 3D Digital/Virtual Outcrop Model (DOM/VOM) development from RGB images (e.g. Structure from Motion, SfM;  Multi Stereo View, MSV; Simultaneous Localization And Mapping, SLAM)  have increased the application of these technology in stability analysis of unstable rock cliffs affected by rock fall due to possibility to perform analysis with higher resolution, accuracy, safety and time-saving to respect the traditional manual techniques, and with higher applicability and affordability to respect the Laser Scanner technology. The principal aims of a geoengineering  inspection of an unstable rock slope are to identify the possible Mode of Failure (MoF) of the rock mass (e.g. planar sliding, wedge sliding, toppling) and to estimate the rock volume that could be involved in a possible failure event. Then these results can be used for further numerical models and applications, as the rock fall simulations, here the uncertainty of the input parameters deeply influence the output results and, therefore, the reliability of the simulation. Due to the novelty of the RPAS-based DOMs, the uncertainty of the stability analysis is not always correctly identified (e.g. uncertainty equal to the DOM accuracy) and, therefore, sometimes the results and conclusion of the analysis could be partially wrong. Identifying and quantifying correctly the uncertainty is really important especially during emergency condition, when crucial decision must be made quickly.</p><p>In this study, the uncertainty of the stability analysis of the unstable rock cliff of Gallivaggio (Western Alps, Italy) is deeply investigated due to the possibility to compare the Mode of Failure and the unstable rock volume estimated before the failure event of the 29th May 2018 onto a DOM developed using the RPAS, with those identified and calculated after the failure. In particular, it is shown as uncertainty component of the instrumental error could be almost totally negligible to respect the components of the manual interpretation and analysis, also when no Ground Control Points (GCPs) are used to develop the DOM.</p>

Stability Analysis of Complex Multibody Systems

2005 ◽  
Vol 1 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Olivier A. Bauchau ◽  
Jielong Wang
Keyword(s):  
Stability Analysis ◽  
Multibody Systems ◽  
Floquet Theory ◽  
Numerical Models ◽  
Characteristic Exponent ◽  
Prony's Method ◽  
Linearized Stability ◽  
The Stability ◽  
Curve Fitting Method ◽  
Prony’S Method

The linearized stability analysis of dynamical systems modeled using finite element-based multibody formulations is addressed in this paper. The use of classical methods for stability analysis of these systems, such as the characteristic exponent method or Floquet theory, results in computationally prohibitive costs. Since comprehensive multibody models are “virtual prototypes” of actual systems, the applicability to numerical models of the stability analysis tools that are used in experimental settings is investigated in this work. Various experimental tools for stability analysis are reviewed. It is proved that Prony’s method, generally regarded as a curve-fitting method, is equivalent, and sometimes identical, to Floquet theory and to the partial Floquet method. This observation gives Prony’s method a sound theoretical footing, and considerably improves the robustness of its predictions when applied to comprehensive models of complex multibody systems. Numerical and experimental applications are presented to demonstrate the efficiency of the proposed procedure.

Stability Analysis of the Earth Embankments Subjected to Natural Cyclic Processes

2017 ◽  
Vol 21 ◽  
pp. 389-396 ◽  
Author(s):  
Smita Tung ◽  
Kaustuv Bhattacharya ◽  
Gupinath Bhandari ◽  
Sibapriya Mukherjee ◽  
Ancuţa Rotaru ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Numerical Models ◽  
High Tide ◽  
Phreatic Surface ◽  
Deltaic Plain ◽  
Freeze Thaw ◽  
The Earth ◽  
Cyclic Processes ◽  
The Stability ◽  
Permeable Soil

The paper brings out the stability analysis of the earth embankments subjected to specific natural cyclic processes such as tides in India and freeze-thaw in Romania. The Sundarban, along the Bay of Bengal, is a low tide-dominated deltaic plain of the Ganga-Brahmaputra-Meghna basin (GBM) spreading over India and Bangladesh around 25,500 sq.km. The 3520km of riverside embankments had been erected to protect the deltaic plain from tidal flooding. The tidal cycle in this region is twice high tide and low tide daily. Presently, the Indian Sundarban Delta is under the threat to embankment failure. The study analyses the stability of an 8 m height embankment in the Gosaba region of Sundarban considering a 2m wide earth filled berm at 6m from the bottom of varying clay core thickness under the transient groundwater flow. Pore pressure, Flow net and Phreatic surface have been obtained by numerical models using FLAC 2D software, thus the factor of safety being analysed. In Romania, built on the of the highway A1 Orăştie-Sibiu section crossing the clayey hills from Aciliu and Apoldu known for their instability, the embankment around the abutment pier from Apoldu broke up at the entry to the Aciliu Viaduct. The layers of permeable soil soaked with water become heavy instead the waterproof layers keep the water above them creating sliding surfaces. The water is channelled to dozens of springs that appear or disappear depending on each micro-slip or fallen water amount. By freezing the water expands on the ground determining additional efforts, the cycle iterating with each rain and freeze-thaw.

scholarly journals Stability Analysis of a Station-TBM Tunnel Intersection Applying Innovative Techniques

2020 ◽  
Vol 8 (5) ◽  
pp. 3886-3894
Keyword(s):  
Stability Analysis ◽  
Numerical Models ◽  
Tunnel Boring Machine ◽  
Optimal Sequence ◽  
Time Saving ◽  
Tunnel Boring ◽  
Finite Element Software ◽  
Construction Techniques ◽  
Partial Filling ◽  
Diaphragm Walls

Tunnel construction using a tunnel boring machine TBM may encounter a coordination difficulty where the machine may reach the station site before the station completion. A construction solution for such a station-TBM intersection is vital. In the Cairo Metro Tunnel-Line 3, Heliopolis station, infrequent construction sequence was adapted, where the station transverse diaphragm walls were firstly installed to let the tunnel boring machine entering the station vicinity and erecting the tunnel lining within and after the station. Afterward, the longitudinal diaphragm walls of the station were installed parallel to the tunnel line. In view of that, the tunnel parts enclosed by the station were required to be safely demolished, followed by completing the remaining station elements. The process of removing the lining segments within the station involves a risk of instability of the existing tunnel because of excessive deformations. Therefore, innovative four construction techniques were suggested and numerically inspected to find an optimal sequence of executing such a hard construction condition. Numerical models, established by the 2-D finite element software, PLAXIS, were adopted in a staged analysis to simulate the construction phases till the critical phase of removing the tunnel segments, where the tunnel stability was considerably reduced. At that point, stability analysis was performed to examine the liability of the four demolishing scenarios. These scenarios include partial filling the tunnel with sand at the demolishing location, and/or using internal or external link members. Lastly, the optimal technique to remove the lining segments inside the station considering stability, economy and time-saving, was decided.

Wellbore Stability Analysis of Coal Seam Based on Hoek-Brown Criterion

2011 ◽  
Vol 383-390 ◽  
pp. 3882-3888 ◽  
Author(s):  
Heng Lin Yang ◽  
Zhong Ian Tian ◽  
Li Song Zhang ◽  
Xiang Zhen Yan
Keyword(s):  
Stability Analysis ◽  
Fractured Rock ◽  
Wellbore Stability ◽  
Coal Bed ◽  
Geological Strength Index ◽  
Strength Criteria ◽  
Collapse Pressure ◽  
Well Bore Stability ◽  
The Stability ◽  
Borehole Size

Stable evaluation of coal strength is needed in coal well-bore stability analysis. The regular analysis method of wellbore stability adopts Mohr-Coulomb strength criteria to judge the collapse pressure. Coal is dual porosity structure and contains joint fissures richly. Hoek-Brown criterion is much more reasonable to estimate the strength of jointed and fractured rock. So Hoek-Brown criterion is used to analyze the stability of multi-lateral horizontal coal bed methane well. Considering the GSI (geological strength index), structural and surface conditions of coal, the coal and rock mass strength parameters are converted into the underground coal mechanical parameters based on the triaxial test of intact coal. According to the stress state of multi-lateral horizontal well, the borehole collapse formulas are established based on Hoek-Brown Criterion. The effects on the wellbore stability, due to the joint fissures of coal, borehole size, drilling disturbance, are also discussed in this paper.

scholarly journals Stability analysis of the Kosciuszko Mound using terrestrial laser scanner and numerical modelling

2018 ◽  
Vol 66 ◽  
pp. 01018
Author(s):  
Elżbieta Pilecka ◽  
Karolina Tomaszkiewicz
Keyword(s):  
Stability Analysis ◽  
Laser Scanner ◽  
Technical Condition ◽  
Point Of View ◽  
Terrestrial Laser Scanner ◽  
The Finite Element Method ◽  
Anthropogenic Soils ◽  
Differential Model ◽  
The Stability ◽  
Selection Of

Landslides which form in anthropogenic soils are complicated from a geological engineering and geotechnical point of view. Each case requires a detailed investigation and the selection of effective reinforcements is a difficult project issue. The study presents the problem of the stability analysis of landslides occurring in the anthropogenic soils of the Kosciuszko Mound in Cracow. The previously performed protections are discussed to highlight their ineffectiveness and the current technical condition of the mound is also presented. By overlapping the results of displacement measurements made with a terrestrial laser scanner, a differential model of the terrain was created which made it possible to determine the size and direction of the deformation of the slopes of the mound and the tendencies for the development of landslide movements in this area. A cross-section, selected on the basis of the model, was numerically analysed using the finite element method (FEM) in the Midas GTS NX program. As a result of the analysis, the values of the displacements and strains occurring in the Mound were calculated. On the basis of the value of the safety factor obtained, it was also possible to assess the risk of landslide movements.

Stability Analysis of Complex Multibody Systems

2005 ◽  
Author(s):  
Olivier A. Bauchau ◽  
Jielong Wang
Keyword(s):  
Stability Analysis ◽  
Floquet Theory ◽  
Numerical Models ◽  
Characteristic Exponent ◽  
Fitting Method ◽  
Prony's Method ◽  
Linearized Stability ◽  
The Stability ◽  
Curve Fitting Method ◽  
Prony’S Method

The linearized stability analysis of dynamical systems modeled using finite element based multibody formulations is addressed in this paper. The use of classical methods for stability analysis of these system, such as the characteristic exponent method or Floquet theory, results in computationally prohibitive costs. Since comprehensive multibody models are “virtual prototypes” of actual systems, the applicability to numerical models of the stability analysis tools that are used in experimental settings is investigated in this work. Various experimental tools for stability analysis are reviewed. It is proved that Prony’s method, generally regarded as a curve fitting method, is equivalent, and sometimes identical, to Floquet theory and to the partial Floquet method. This observation gives Prony’s method a sound theoretical, footing, and considerably improves the robustness of its predictions when applied to comprehensive models of complex multibody system. Numerical applications are presented to demonstrate the efficiency of the proposed procedure.

scholarly journals Application of the terrestrial laser scanner in the monitoring of earth structures

2020 ◽  
Vol 12 (1) ◽  
pp. 503-517
Author(s):  
Janusz P. Kogut ◽  
Elżbieta Pilecka
Keyword(s):  
Laser Scanning ◽  
Numerical Models ◽  
Laser Scanner ◽  
The Finite Element Method ◽  
Earth Structures ◽  
Multiple Measurements ◽  
The Stability ◽  
Term Monitoring ◽  
Ground Material

AbstractTerrestrial laser scanning (TLS) assists in the detection of the unsafe behaviour of slopes and scarps. It also facilitates the assessment of the stability of earthworks. Earth structures are those that are usually made of qualified ground material. One may distinguish between point structures such as mounds, forts and dams, and linear structures such as roads, railways and flood embankments. This article concerns the problem of monitoring and analysing of the effects associated with the unstable behaviour of selected earth structures. TLS enables remote sensing of surface changes in a simple and automated manner. Regular, multiple measurements with the laser scanner are applied in long-term monitoring of the behaviour of the selected objects. The discrete numerical models using, for example, the finite element method (FEM) take into account geotechnical properties of substrate and allow for the risk assessment and stability testing of such structures. The numerical model of the structure along with the parameters of the substrate are introduced into the FEM package. This allows for the analysis of stresses, strains and displacements, along with different loading cases. The work here presents a few selected earth structures for which the aforementioned analyses have been undertaken.

scholarly journals Mechanical Parameter Inversion in Sandstone Diversion Tunnel and Stability Analysis during Operation Period

2019 ◽  
Vol 5 (9) ◽  
pp. 1917-1928 ◽  
Author(s):  
Zhaoqiang Wang ◽  
Xin Chen ◽  
Xinhua Xue ◽  
Lei Zhang ◽  
Wenkai Zhu
Keyword(s):  
Stability Analysis ◽  
Constitutive Model ◽  
Rheological Behavior ◽  
Numerical Models ◽  
High Stress ◽  
Geological Condition ◽  
Mechanical Parameters ◽  
Finite Element Software ◽  
Parameter Inversion ◽  
The Stability

A large number of experimental studies show that the mechanical parameters of deep buried surrounding rock show significant attenuation characteristics with the increase of strain from the rheological acceleration stage to the attenuation stage. However, the existing numerical models all take mechanical parameters as constants when describing the rheological behavior of surrounding rocks, which can only be applied to the stability analysis of the shallowly buried tunnel. Therefore, this work proceeding from the actual project, improved the sandstone rheological constitutive model and optimized the algorithm of parameter inversion, and put forward a long-term stability analysis model that can accurately reflect the rheological characteristics of surrounding rocks under the complex geological condition including high stress induced by great depth and high seepage pressure. In the process, a three-dimensional nonlinear rheological damage model was established based on Burgers rheological model by introducing damage factors into the derivation of the sandstone rheological constitutive model to accurately describe the rheological behaviors of the deep buried tunnel. And BP (Back Propagation) neural network optimized by the multi-descendant genetic algorithm is used to invert the mechanical parameters in the model, which improves the efficiency and precision of parameter inversion. Finally, the rheological equation was written by using parametric programming language and incorporated into the general finite element software ANSYS to simulate the rheological behavior of the tunnel rock mass at runtime. The results of the model analysis are in good agreement with the monitoring data in the later stage. The research results can provide a reference for the stability analysis of similar projects.

Stability analysis of the surrounding rock of cavern under extreme situation based on limited borehole data.

2021 ◽  
Author(s):  
Long Tan ◽  
Wei Xiang
Keyword(s):  
Stability Analysis ◽  
Fractured Rock ◽  
Extreme Case ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Borehole Data ◽  
Geological Conditions ◽  
Set Up ◽  
The Stability ◽  
Fractured Rock Masses

<p>In the pre-feasibility study stage, only a small amount of borehole data can be obtained. Since the available geological information is insufficient, the engineering geological conditions of the project can only be preliminarily and approximately estimated during this stage. In this study, we attempt to seek a method to make a preliminary analysis and evaluation of the stability of the surrounding rock masses of an underground rock carven project, which makes full and optimum use of the limited borehole data to accomplish the assessment of the investigated site. The basic information on rock fractures is extracted from the borehole Television logging data and the fracture extension directions are also determined. Providing that the cracks detected in the borehole would extend to the cavern area, the cracks with appropriate direction, larger width and larger hydraulic conductivity can be selected. These selected cracks are considered in the numerical model established using ANSYS, and the stability of surrounding rock of cavern is analyzed under this situation. In the absence of large amount of borehole data, this method, which set up an extreme case, can be used to analyze possible failure of rock mass under extreme adverse conduction in advance. In general, the proposed method for stability analysis could contribute to the design and construction practice of a tunnel project constructed in fractured rock masses.</p>

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