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1 – 10 of over 16000Yongxing Guo, Jianjun Fu, Longqi Li and Li Xiong
Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability…
Abstract
Purpose
Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability mechanisms. Simply observing the slope landslide before and after a centrifugal model test cannot reveal the processes involved in real-time deformation. Electromagnetic sensors have severed as an existing method for real-time measurement, however, this approach has significant challenges, including poor signal quality, interference, and complex implementation and wiring schemes. This paper aims to overcome the shortcomings of the existing measurement methods.
Design/methodology/approach
This work uses the advantages of fiber Bragg grating (FBG) sensors with their small form-factor and potential for series multiplexing in a single fiber to demonstrate a monitoring strategy for model centrifugal tests. A slope surface deformation displacement sensor, FBG anchor sensor and FBG anti-slide piling sensor have been designed. These sensors are installed in the slope models, while centrifugal acceleration tests under 100 g are carried out.
Findings
FBG sensors obtain three types of deformation information, demonstrating the feasibility and validity of this measurement strategy.
Originality/value
The experimental results provide important details about instability mechanisms of a slope, which has great significance in research on slope model monitoring techniques and slope stability.
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Alireza Ahangar‐Asr, Asaad Faramarzi and Akbar A. Javadi
Analysis of stability of slopes has been the subject of many research works in the past decades. Prediction of stability of slopes is of great importance in many civil engineering…
Abstract
Purpose
Analysis of stability of slopes has been the subject of many research works in the past decades. Prediction of stability of slopes is of great importance in many civil engineering structures including earth dams, retaining walls and trenches. There are several parameters that contribute to the stability of slopes. This paper aims to present a new approach, based on evolutionary polynomial regression (EPR), for analysis of stability of soil and rock slopes.
Design/methodology/approach
EPR is a data‐driven method based on evolutionary computing, aimed to search for polynomial structures representing a system. In this technique, a combination of the genetic algorithm and the least square method is used to find feasible structures and the appropriate constants for those structures.
Findings
EPR models are developed and validated using results from sets of field data on the stability status of soil and rock slopes. The developed models are used to predict the factor of safety of slopes against failure for conditions not used in the model building process. The results show that the proposed approach is very effective and robust in modelling the behaviour of slopes and provides a unified approach to analysis of slope stability problems. It is also shown that the models can predict various aspects of behaviour of slopes correctly.
Originality/value
In this paper a new evolutionary data mining approach is presented for the analysis of stability of soil and rock slopes. The new approach overcomes the shortcomings of the traditional and artificial neural network‐based methods presented in the literature for the analysis of slopes. EPR provides a viable tool to find a structured representation of the system, which allows the user to gain additional information on how the system performs.
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Chunli Li, Liang Li, Yungming Cheng, Liang Xu and Guangming Yu
This paper aims to develop an efficient algorithm combining straightforward response surface functions with Monte Carlo simulation to conduct seismic reliability analysis in a…
Abstract
Purpose
This paper aims to develop an efficient algorithm combining straightforward response surface functions with Monte Carlo simulation to conduct seismic reliability analysis in a systematical way.
Design/methodology/approach
The representative slip surfaces are identified and based on to calibrate multiple response surface functions with acceptable accuracy. The calibrated response surfaces are used to determine the yield acceleration in Newmark sliding displacement analysis. Then, the displacement-based limit state function is adopted to conduct seismic reliability analysis.
Findings
The calibrated response surface functions have fairly good accuracy in predicting the yield acceleration in Newmark sliding displacement analysis. The seismic reliability is influenced by such factors as PGA, spatial variability and threshold value. The proposed methodology serves as an effective tool for geotechnical practitioners.
Originality/value
The multiple sources of a seismic slope response can be effectively determined using the multiple response surface functions, which are easily implemented within geotechnical engineering.
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Chen-Xi Han, Tian-Shun Hou and Ye Chen
To solve the instability problem of Zhangjiayao landslide caused by rainfall, the internal mechanism of slope instability and the supporting effect of anti-slide piles are…
Abstract
Purpose
To solve the instability problem of Zhangjiayao landslide caused by rainfall, the internal mechanism of slope instability and the supporting effect of anti-slide piles are studied. The research results can provide theoretical basis for the prevention and control of loess landslides.
Design/methodology/approach
A three-dimensional finite element model of Zhangjiayao landslide is established by field geological survey, laboratory test and numerical simulation.
Findings
The results show that Zhangjiayao landslide is a loess-mudstone contact surface landslide, and rainfall leads to slope instability and traction landslide. The greater the rainfall intensity, the faster the pore water pressure of the slope increases and the faster the matrix suction decreases. The longer the rainfall duration, the greater the pore water pressure of the slope and the smaller the matrix suction. Anti-slide pile treatment can significantly improve slope stability. The slope safety factor increases with the increase of embedded depth of anti-slide pile and decreases with the increase of pile spacing.
Originality/value
Based on the unsaturated soil seepage theory and finite element strength reduction method, the failure mechanism of Zhangjiayao landslide was revealed, and the anti-slide pile structure was optimized and designed based on the pile-soil interaction principle. The research results can provide theoretical basis for the treatment of loess landslides.
Highlights
A three-dimensional finite element model of Zhangjiayao landslide is established.
Zhangjiayao landslide is a loess-mudstone contact surface landslide.
The toe of Zhangjiayao slope is first damaged by heavy rainfall, resulting in traction landslide.
The deformation of Zhangjiayao slope is highly dependent on rainfall intensity and duration.
The anti-slide pile can effectively control the continuous sliding of Zhangjiayao slope.
A three-dimensional finite element model of Zhangjiayao landslide is established.
Zhangjiayao landslide is a loess-mudstone contact surface landslide.
The toe of Zhangjiayao slope is first damaged by heavy rainfall, resulting in traction landslide.
The deformation of Zhangjiayao slope is highly dependent on rainfall intensity and duration.
The anti-slide pile can effectively control the continuous sliding of Zhangjiayao slope.
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Chengfu Hu, Chong Shi, Yiping Zhang, Xiao Chen and Sha Luo
Cemented conglomerate accumulation is a weak and heterogeneous medium that occurs in western China. It consists mainly of argillaceous cement that loses strength rapidly upon…
Abstract
Purpose
Cemented conglomerate accumulation is a weak and heterogeneous medium that occurs in western China. It consists mainly of argillaceous cement that loses strength rapidly upon contact with water, leading to collapse instability failure. Its deformation failure mechanism is complex and poorly understood. In this paper, the erosion failure mechanism of cemented conglomerate accumulation is investigated.
Design/methodology/approach
The collapse failure process after erosion of the slope foot for typical cemented conglomerate accumulation is studied based on field investigation using the particle discrete element method. And how the medium composition, slope angle and cementation degree influence the failure mode and process of the cemented conglomerate accumulation is examined.
Findings
The foot erosion of slope induces a tensile failure that typically manifests as “erosion at the foot of slope – tensile cracking at the back edge of slope top – integral collapse.” The collapse failure is more likely to occur when the cemented conglomerate accumulation has a higher rock content, a steeper slope angle or a weaker cementation degree.
Originality/value
A model based on rigid blocks and disk particles to simulate the cemented conglomerate accumulation is developed. It shows that the hydraulic erosion at the foot of the slope resulted in a different failure mechanism than that of general slopes. The results can inform the stability management, disaster prevention and mitigation of similar slopes.
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Houlai Lin, Liang Li, Kaiqi Meng, Chunli Li, Liang Xu, Zhiliang Liu and Shibao Lu
This paper aims to develop an effective framework which combines Bayesian optimized convolutional neural networks (BOCNN) with Monte Carlo simulation for slope reliability…
Abstract
Purpose
This paper aims to develop an effective framework which combines Bayesian optimized convolutional neural networks (BOCNN) with Monte Carlo simulation for slope reliability analysis.
Design/methodology/approach
The Bayesian optimization technique is firstly used to find the optimal structure of CNN based on the empirical CNN model established in a trial and error manner. The proposed methodology is illustrated through a two-layered soil slope and a cohesive slope with spatially variable soils at different scales of fluctuation.
Findings
The size of training data suite, T, has a significant influence on the performance of trained CNN. In general, a trained CNN with larger T tends to have higher coefficient of determination (R2) and smaller root mean square error (RMSE). The artificial neural networks (ANN) and response surface method (RSM) can provide comparable results to CNN models for the slope reliability where only two random variables are involved whereas a significant discrepancy between the slope failure probability (Pf) by RSM and that predicted by CNN has been observed for slope with spatially variable soils. The RSM cannot fully capture the complicated relationship between the factor of safety (FS) and spatially variable soils in an effective and efficient manner. The trained CNN at a smaller the scale of fluctuation (λ) exhibits a fairly good performance in predicting the Pf for spatially variable soils at higher λ with a maximum percentage error not more than 10%. The BOCNN has a larger R2 and a smaller RMSE than empirical CNN and it can provide results fairly equivalent to a direct Monte Carlo Simulation and therefore serves a promising tool for slope reliability analysis within spatially variable soils.
Practical implications
A geotechnical engineer could use the proposed method to perform slope reliability analysis.
Originality/value
Slope reliability can be efficiently and accurately analyzed by the proposed framework.
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The purpose of this paper is to attempt to generate a better, systematic and scientific understanding of the basic reasons behind slope instability to help in developing the basic…
Abstract
Purpose
The purpose of this paper is to attempt to generate a better, systematic and scientific understanding of the basic reasons behind slope instability to help in developing the basic principles of landslide hazard zonation, monitoring and forecasting of landslide hazards for better and more effective landslide hazard mitigation and management.
Design/methodology/approach
The study is based on extensive field observations and intensive reviews of literature from secondary sources.
Findings
Mass movements especially landslides as they are known to common man are a recurring natural phenomenon and are an integral part of any geological/geomorphological circle of landform development through sequential development of slopes in any elevated region and especially in young fold mountain chains.
Practical implications
The paper presents a valuable insight into the basic reasons behind a landslide to spread awareness, to educate and sensitize people towards better and effective landslide hazard mitigation and thereby ensure people's participation in disaster management. It also aims to initiate and encourage research in the field of landslide management.
Originality/value
Landslides occur frequently and without any appreciable warning as such causing havoc and often insurmountable damage to life and property but despite their uncertainty, their causative factors and indicators of slope instability are very well known to an extent that the magnitude of these events, susceptible areas, the timing of such events and their potential impact can be studied, analyzed and evaluated on the basis of past occurrences and existing knowledge to mitigate their impact. The real value of the present study is to minimize losses due to landslides through better knowledge and enhanced levels of understanding of the phenomenon and its management by simply avoiding those particular reasons that could lead to slope instability problems.
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Mass movements, especially landslides, are a recurring natural phenomenon and are an integral part of any geological/geomorphological cycle of landform development through…
Abstract
Purpose
Mass movements, especially landslides, are a recurring natural phenomenon and are an integral part of any geological/geomorphological cycle of landform development through sequential development of slopes in any elevated region and especially in young fold mountain chains. The purpose of this paper is to develop and evolve cheap, affordable, environment friendly and ecologically sustainable techniques of landslide disaster management and prevention.
Design/methodology/approach
The study is based on extensive research and field observations of various landslide management projects over the past decade and includes an intensive review of literature from secondary sources.
Findings
Landslide management aims to facilitate, and as far as possible accelerate the ongoing process of development on a sustainable basis, by preventing (reducing) the loss of lives and property by applying modern science and technology and taking appropriate measures and safety precautions at the right place at the right time. Landslide management, even in the most developed countries, has suffered from lack of adequate financial resources. Bioengineering offers an environment friendly and highly cost and time effective solution to the slope instability problems in mountainous and hilly areas.
Practical implications
The paper aims to initiate and encourage research in the field of landslide management with the viewpoint that green technology is a clean and affordable technology (both financially and ecologically).
Originality/value
The paper shows that bioengineering is highly cost effective and has very high cost‐benefit ratio. Bioengineering techniques when used in combination with civil and social engineering measures reduce the overall cost of landslide mitigation considerably which is the key factor for developing nations. Bioengineering has a very high success rate and is much more sustainable, eco‐friendly and affordable than other available options.
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Ke Ma, Yu Li, Guoyang Liu, Gang He, Chun Sha and Yilin Peng
The purpose of this study is to investigate the deformation characteristics and failure modes of the right bank slope of Xiluodu Hydropower Station after excavation.
Abstract
Purpose
The purpose of this study is to investigate the deformation characteristics and failure modes of the right bank slope of Xiluodu Hydropower Station after excavation.
Design/methodology/approach
Micro-seismic monitoring technology is applied to obtain the microfracture information and study the internal damage evolution law of the slope rock mass. A numerical model for discontinuous deformation analysis (DDA) is established to analyse the deformation characteristics and failure mode of the slope. Micro-seismic monitoring and DDA can verify and supplement each other's results in the investigation of slope failure.
Findings
The results show that the slope has a downhill displacement along the weathered zone under natural conditions; the maximum resultant displacement at the monitoring point is 380 mm. The micro-seismic events are concentrated in an area located 30–100 m horizontally away from the slope surface and at an elevation of 390–470 m. The distribution of these micro-seismic events is consistent with the location of the unloading and weathered zones; it is the same as the DDA simulation result.
Originality/value
The study is anticipated to be used as reference for the stability analysis of rock slopes. By combining the continuous (micro-seismic monitoring technology) and discontinuous (DDA) methods, the entire process starting from the gradual accumulation of internal rock micro-damage to the macroscopic discontinuous deformation and failure of the slope can be investigated.
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Previous literature shows that market sentiment and the steepness of index option's implied volatility slope have a negative relation. This paper investigates the relation between…
Abstract
Purpose
Previous literature shows that market sentiment and the steepness of index option's implied volatility slope have a negative relation. This paper investigates the relation between firm-specific sentiment and individual option's implied volatility slope both theoretically and empirically.
Design/methodology/approach
The authors develop a simple model with option traders' sentiment heterogeneity to show that sentiment and the steepness of individual option's implied volatility slope have a positive relation.
Findings
When firm-specific sentiment is higher (more bullish), individual option's implied volatility slope becomes steeper. The positive relation is stronger when option traders' beliefs on risk are more dispersed. Empirical results support the theoretical model predictions.
Originality/value
Although both firm-specific sentiment and individual options implied volatility slope predict future stock returns, there is no research exploring the relation between them. In particular, none of previous studies associates implied volatility slope's stock return predictability to investor behavior such as sentiment. The authors’ findings provide a behavior-based explanation on why steep implied volatility slope negatively predicts cross-sectional stock returns.
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