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\"This book contains the detailed reflections of its author who has practised and researched in the field for over a half century. It is written in an informal style that makes it an interesting and thought-provoking practitioner guide to landslides and slope problems and their investigation, analysis, and remediation, considering both natural and man-made slopes and earthworks, and without the need for the usual equations and illustrations. Reflections on Slope Stability Engineering is targeted primarily at practitioners working in the investigations of slope instability and the design and construction of treatments of the problem, especially those early in their careers, but the accessible style also suits students who are developing an interest in the subject and even those engineers with only a casual interest in this branch of geotechnics\"-- Provided by publisher.

Particle swarm optimization (PSO) is an evolutionary computation approach to solve nonlinear global optimization problems. The PSO idea was made based on simulation of a simplified social system, the graceful but unpredictable choreography of birds flock. This system is initialized with a population of random solutions that are updated during iterations. Over the last few years, PSO has been extensively applied in various geotechnical engineering aspects such as slope stability analysis, pile and foundation engineering, rock and soil mechanics, and tunneling and underground space design. A review on the literature shows that PSO has utilized more widely in geotechnical engineering compared with other civil engineering disciplines. This is due to comprehensive uncertainty and complexity of problems in geotechnical engineering which can be solved by using the PSO abilities in solving the complex and multi-dimensional problems. This paper provides a comprehensive review on the applicability, advantages and limitation of PSO in different disciplines of geotechnical engineering to provide an insight to an alternative and superior optimization method compared with the conventional optimization techniques for geotechnical engineers.

Climate change is known to cause alterations in weather patterns and disturb the natural equilibrium. Changes in climatic conditions lead to increased environmental stress on embankments, which can result in slope failures. Due to wetting–drying cycles, expansive clayey soil often swells and shrinks, and matric suction is a major factor that controls the behavior. Increased temperature accelerates soil evaporation and drying, which can cause desiccation cracks, while precipitation can rapidly reduce soil shear strength. Desiccated slopes on embankments built with such soils can cause surficial slope failures after intense precipitation. This study used slope stability analysis to quantify how climate-change-induced extreme weather affects embankments. Historic extreme climatic events were used as a baseline to estimate future extremes. CMIP6 provided historical and future climatic data for the study area. An embankment was numerically modeled to evaluate the effect on slope stability due to the precipitation change induced by climate change. Coupled hydro-mechanical finite element analyses used a two-dimensional transient unsaturated seepage model and a limit equilibrium slope stability model. The study found that extreme climatic interactions like precipitation and temperature due to climate change may reduce embankment slope safety. The reduction in the stability of the embankment due to increased precipitation resulting from different greenhouse gas emission scenarios was investigated. The use of unsaturated soil strength and variation of permeability with suction, along with the phase transition of these earthen embankments from near-dry to near-saturated, shows how unsaturated soil mechanics and the hydro-mechanical model can identify climate change issues on critical geotechnical infrastructure.

Rainfall leads to the deterioration of slope stability conditions, while intense rainfall has been commonly associated with landslides on natural or engineered slopes. Deep excavations, typically related to geo-resources exploitation, e.g., in the case of surface mining, are often affected by rainfall events that jeopardize their stability. In this work, rainfall infiltration is directly incorporated in the slope stability analysis; this investigation is currently missing from the literature as mainly empirical methods are used regarding deep excavations. The very deep slopes from lignite mines are employed as typical examples, often reaching 200 m and presenting smooth inclinations and fine-grained soils. A general numerical framework was used; the safety factor’s deterministic analysis was supplemented by a Monte Carlo investigation to determine the probability of failure. The importance of the involved parameters—slope geometry, rainfall intensity, and soil properties—was studied through a parametric analysis. Initially, a typical slip surface is presented, relatively deep and reaching from toe to crest. The critical mechanism was the development—after the rainfall—of a smaller and more local than the initial (before rainfall) slip surface. Although the final surface is smaller than the initial one, it can be more than 50 m high denoting a significant hazard. The most influential parameters are rainfall intensity, soil permeability, and slope height. This study can serve as a basis for similar preliminary analysis in practice. Stability and reliability analysis reveals the need to supplement conventional safety factors with the probability of failure for a broader and improved overview.

A large landslide (40 × 10 6  m 3 ) was reactivated on the left bank of Canelles reservoir, Spain. The instability was made evident after a considerable reduction of the reservoir level. The drawdown took place during the summer of 2006 after several years of high water levels. The drawdown velocity reached values between 0.5 and 1.2 m/day (registered at low elevations). The paper reports the geological and geotechnical investigations performed to define the movement. The geometry of the slip surface was established from the detailed analysis of the continuous cores recovered in deep borings and from limited information provided by inclinometers. Deep piezometric records provided also valuable information on the pore water pressure in the vicinity of the failure surface. These data allowed validating a flow–deformation coupled calculation model, which takes into account the changes in water level that occurred 4  years previous to the failure as well as the average rainfall. The analysis indicates that the most likely reason for the instability is the rapid drawdown that took place during the summer of 2006. The potential sudden acceleration of the slide is also analysed in the paper introducing coupled thermal hydraulic and mechanical effects that may develop at the basal shearing surface of the sliding mass. The results indicate that the slide velocity may reach values around 16 m/s when displacement reaches 250 m.

The common slope stability analysis is incapable of accurately forecasting shallow slides where suction pressures play a critical role. This realization is used for elaborate stability analyses which include soil suction to better predict rainfall-induced slides at railway embankment at Malda where three known cases of slope failures and train derailments occurred after heavy rainfall. The relationship between the soil–water content and the matric suction is established for the embankment soil. It is then used in the coupled analyses of seepage and slope stability to estimate performances of the embankment at different intensity and duration of rainfall. The numerical simulations are performed with the FE code Geo-Studio. The numerical results show significant reduction in the factor of safety of the railway embankment with the increase in the intensity and duration of rainfall. The effectiveness of the proposed mitigation measures including placement of 2 m-wide free draining rockfill across the slopes and drilling 5-m-long sheet pile wall at the toe of the embankment is studied numerically. The study confirms that the proposed mitigation measures effectively increase the factor of safety of the embankment and stabilizing it even in case of a heavy rainfall of 25 mm/h over 12 h.

Seismic stability analyses of soil slopes in the presence of weak interlayers are rather challenging within the framework of plasticity theory, due to the construction of kinematically admissible velocity fields and statically allowable stress fields at limit state. Finite-element limit-analysis procedures including finite-element upper-bound (FEUB) and finite-element lower-bound (FELB) approach are introduced in this study, retaining the merits of FEM and limit analysis theory to tackle above issues. Incorporating modified pseudo-dynamic approach, seismic slope stability analyses are transformed to linear programming models, in terms of lower- and upper-bound formulations. Pseudo-static and modified pseudo-dynamic solutions of the factor of safety (FoS) are sought through optimization with an interior-point algorithm. An appealing merit of the proposed procedure is that both lower and upper bounds are searched, aiding to better estimate the true solution of FoS. Limit equilibrium and Abaqus are applied to validate FEUB and FELB results. Effects of dual weak interlayers’ position and dimension on seismic slope stability are investigated. Critical failure surface and velocity field are plotted by post-processing, demonstrating a rotational-translational failure mechanism. Based on less than 5% difference between lower- and upper-bound solutions, the proposed procedure is capable of providing a reliable guidance for slope design and assessment.

The probabilistic bearing capacity of the strip footing placed near a two-layered cohesive soil slope is evaluated using random adaptive finite element limit analysis with anisotropic random field modeling and Monte Carlo simulation techniques. To account for the combined effect of geometric parameters (i.e., normalized slope heights, and slope angles), soil properties (i.e., ratio of undrained shear strength from two-layer soils) and spatially variable strengths of two-layered soil, the bearing capacity is quantitatively examined in stochastic analysis. Moreover, a sensitivity analysis is exhibited, and the optimal layout of footings near a two-layered slope is estimated through a multivariate adaptive regression splines procedure. The associated results demonstrate that the slope angle has the most significant impact on the mean bearing capacity, while the coefficient of variation of the ultimate bearing capacity factor could be greatly reduced by decreasing the variability of the upper layer soil. The interaction effects between these influencing factors are numerically investigated. This study highlights the prominent role of the variability in lower layer soil when the coupled influence of geometric conditions and soil properties is considered.

The microbial‑induced carbonate precipitation (MICP), as an emerging biomineralization technology mediated by specific bacteria, has been a popular research focus for scientists and engineers through the previous two decades as an interdisciplinary approach. It provides cutting-edge solutions for various engineering problems emerging in the context of frequent and intense human activities. This paper is aimed at reviewing the fundaments and engineering applications of the MICP technology through existing studies, covering realistic need in geotechnical engineering, construction materials, hydraulic engineering, geological engineering, and environmental engineering. It adds a new perspective on the feasibility and difficulty for field practice. Analysis and discussion within different parts are generally carried out based on specific considerations in each field. MICP may bring comprehensive improvement of static and dynamic characteristics of geomaterials, thus enhancing their bearing capacity and resisting liquefication. It helps produce eco-friendly and durable building materials. MICP is a promising and cost-efficient technology in preserving water resources and subsurface fluid leakage. Piping, internal erosion and surface erosion could also be addressed by this technology. MICP has been proved suitable for stabilizing soils and shows promise in dealing with problematic soils like bentonite and expansive soils. It is also envisaged that this technology may be used to mitigate against impacts of geological hazards such as liquefaction associated with earthquakes. Moreover, global environment issues including fugitive dust, contaminated soil and climate change problems are assumed to be palliated or even removed via the positive effects of this technology. Bioaugmentation, biostimulation, and enzymatic approach are three feasible paths for MICP. Decision makers should choose a compatible, efficient and economical way among them and develop an on-site solution based on engineering conditions. To further decrease the cost and energy consumption of the MICP technology, it is reasonable to make full use of industrial by-products or wastes and non-sterilized media. The prospective direction of this technology is to make construction more intelligent without human intervention, such as autogenous healing. To reach this destination, MICP could be coupled with other techniques like encapsulation and ductile fibers. MICP is undoubtfully a mainstream engineering technology for the future, while ecological balance, environmental impact and industrial applicability should still be cautiously treated in its real practice.

Although the impervious layer under a hydraulic structure is rarely flat, the effect of the impervious layer’s slope, under the hydraulic structure, on seepage characteristics has not been studied to date. Therefore, this study investigated the effect of the downhill and uphill impervious layer’s slope (downhill/uphill foundation slopes) on the uplift pressure, seepage discharge and exit gradient under hydraulic structures. In order to reach this goal, a numerical model has been developed in which the general equation of fluid flow in non-uniform; anisotropic soil is solved by the finite volume method on a structured grid. The model validation was performed using the measured data from experimental tests. The results of the model validation indicated that the model calculates the seepage discharge and uplift pressure with a maximum error of less than 3.79% and 3.25%, respectively. The results also indicated that by increasing the downhill foundation slope (DFS) the uplift force decreases, but the exit gradient and seepage discharge increase. Moreover, by increasing the uphill foundation slope (UFS), the uplift force increases but the exit gradient and seepage discharge decrease. In addition, the results demonstrate that by increasing the length of the cut-off wall the effect of the DFS on decreasing and UFS on increasing the uplift pressure force becomes more severe. However, the effect of the DFS on increasing the seepage discharge and UFS on decreasing the seepage discharge becomes milder as the length of the cut-off wall increases. By increasing the DFS, from zero to −15%, the exit gradient increases 19.75% and 14.4% for 1 m and 6 m cut-off lengths, respectively.