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This study introduces a novel geotechnical composite material comprising two types of fill material sourced from the paper industry—deinking paper sludge ash (DPSA) and deinking paper sludge (DPS). Five composites with different DPSA and DPS contents were investigated. Two composites were selected for further analyses. The technology and procedure for composite installation were implemented in field tests. The composites with 80% and 70% DPSA exhibited the elasticity required to withstand minor landslide slip deformations, in addition to achieving sufficiently high values of uniaxial compressive strength. The composites had a low maximum dry density value, which led to fewer settlements in the entire support structure. The enhanced shear characteristics can enable the construction of a thinner retaining wall. The delay between preparation and installation of the composites was further investigated. The field tests confirmed that the composites with 80% and 70% DPSA can be installed on the construction site 4 h and even 24 h after mixing. In 2018, a retaining wall structure with 70% DPSA and 30% DPS was successfully implemented near a railway line using conventional technology as followed-up research to the herein presented study. Results have been derived from work performed in the scope of the H2020 Paperchain project in which novel circular economy models centered on the valorization of the waste streams generated by the pulp and paper industry as secondary raw material for several resource-intensive sectors, including the construction sector, have been developed. Environmental benefits are savings in natural raw materials, reduction of landfill disposal as well as CO2 emission reduction. [ABSTRACT FROM AUTHOR]

The current active earth pressure calculation theory cannot take into account the influence of the foundation inverse slope. For the translational mode retaining wall in this paper, taking cohesive backfill as the research object, the clay within the crack depth range is equivalent to uniform overload, using the upper limit theory, establishing the energy conservation equation of the velocity field and force, and the analytical formula of the tensile crack depth and the slip surface of the cohesive backfill being obtained. By taking into account the soil arching effect, setting up the static equilibrium equation by horizontal layer analysis, deriving the active earth pressure calculation expression of cohesive backfill, it is possible to consider the influence of the basement inverse slope. In the case of cohesionless backfill, the formula can be reduced to the theoretical solution. By comparing the calculated results with the experimental values and relevant theories, this can verify the applicability of the formula. The result of research shows that, with the increase of the basement inverse slope angle, the development of the tensile crack will be promoted, the dip angle of the slip surface changes little, and the resultant force and overturning moment will decrease, which is conducive to the antisliding stability and antioverturning stability of the wall, reducing the project cost. The active earth pressure distribution of cohesionless backfill is independent of whether there is an inverse slope in the basement. The theoretical formula obtained in this paper can be used as reference for the design of the retaining wall. [ABSTRACT FROM AUTHOR]

This paper pertains to the finite-element lower bound limit analysis (FELA-LB) of vertical strip anchors embedded in cohesionless and cohesive soils and subjected to static and earthquake forces (using pseudostatic analysis) to estimate the optimal horizontal pullout capacity using nonlinear programming (NLP) technique for isolating the optimal solution. In the developed procedure, a mesh of finite-number triangular elements and assuming a linear stress field that satisfies all the equations of internal equilibrium at all points within the soil medium, elemental interface equilibrium, boundary conditions and no-yield conditions at all the nodal points, has been adopted. In contrast to the use of linear programming (LP), as used in the early phase of the development of FELA of stability problems, in the adopted optimization scheme (NLP), the nonlinear no-yield conditions are incorporated directly, eliminating the necessity of successive linearization of the no-yield constraints. The convergence of the solutions (by varying the number of elements in the soil mesh) and extensibility of the selected stress field (by extending the mesh of elements) has been checked and ensured. The correctness of the estimated lower bound has been checked by comparing the obtained solutions with those reported in the literature. Parametric studies showing the effect of the embedment depth of the vertical anchor, soil properties, and earthquake acceleration on the horizontal pullout capacity of the vertical anchor have also been presented in the paper. Practical Applications: Anchor plates are used in the design and construction of foundation for retaining walls, sheet piles, bulkheads, transmission towers, bridge abutments, and buried pipelines to withstand the horizontal, vertical, or inclined loads. The present study adds to the existing state of art for the design and installation of anchor systems subjected to static and seismic conditions and may improve the performance of such foundation systems. [ABSTRACT FROM AUTHOR]

Worldwide, an increasingly huge number of end-of-life tires (ELTs) are disposed of in landfills, illegally dumped, or otherwise unaccounted for, which causes significant environmental and socioeconomic issues. Finding sustainable engineering solutions to recycle and reuse ELTs, which transform them from unwanted waste into useful resources, has become a priority. In geotechnical engineering, researchers have performed laboratory and field tests to determine the mechanical properties of innovative geomaterials that consist of soil–rubber mixtures (SRMs) [i.e., gravel–rubber mixtures (GRMs)] that are obtained using recycled ELT-derived granulated rubber aggregates. Suitable engineering properties and low installation cost encourage the use of GRMs and SRMs in many applications, such as in free-draining energy-adsorption backfill material for retaining walls, underground layers for liquefaction mitigation and geotechnical seismic isolation systems for structures and infrastructures. However, due to the heterogeneity of SRMs, their ultimate adoption as geomaterials must be supported by constitutive relationships that can accurately describe their mechanical behavior under typical field loading conditions. The aim of the paper is to evaluate the effectiveness and limits of the hardening soil model with small strain stiffness (HS-small), which is present in many finite-element (FE) codes, to model the behavior of GRMs in geotechnical engineering applications. An extensive finite-element method simulation of drained triaxial tests was performed. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review of soil nailing as a technique for strengthening slopes and retaining walls. It deliberates various methods and materials associated with soil nailing, while also examining the advantages and disadvantages of this approach. The review incorporates previous studies to demonstrate the extensive practical application of soil nailing. To study the influence of soil nail stiffness, both physical modelling and numerical techniques, such as Finite Element Method (FEM) and Finite Difference Method (FDM), are studied. The conclusions confirm that soil nailing is a reliable and very effective method for improving soil strength and minimising settlement. Also, the review highlights the significance of considering the bending stiffness of soil nails to optimise the effectiveness of this technique in ground improvement projects. As a result, this review paper serves as a valuable resource for engineers seeking guidance in soil nailing techniques. The primary objective of this paper is to explore fundamental concepts and state-of-the-art approaches in soil slope stability, with a particular focus on soil-nailed slopes and walls. [ABSTRACT FROM AUTHOR]

This article presents the results of an experimental study carried out to assess the possibility of using waste wind turbine blades as retaining wall structures for slopes and trenches. The use of Vestas and LM-type blades as retaining wall components was assumed, based on 'columns' made of Vestas-type closed profiles filled with concrete and 'slabs' of fragments extracted from LM-type blades. The results of the tests and comparisons of the displacement and strain values of the components obtained using different measurement methods are presented in this paper. The force–strain and force–displacement relationships obtained from the tests were used to validate numerical models of slope protection walls and excavations designed from used wind turbine blades. According to our research, there is a high degree of variability in the strength parameters and deformation of the composite elements made from the wind turbine blades. Therefore, in the case of this type of material, characterized by a significant variation in carrying capacity, deformability, and the nature of the failures, the use of different measurement methods makes it possible to obtain much of the data necessary for assessing the reusability of wind turbine blades in building. [ABSTRACT FROM AUTHOR]

Active earth pressure on retaining structures supporting a narrow column of soil cannot be properly analysed using Coulomb's theory. Finite-element limit analysis (FELA) shows that the soil forms multiple failure surfaces if the soil column is sufficiently narrow. This paper proposes a framework for active earth pressure estimation for narrow soils by combining an arched differential element method and a sliding wedge method. The analytical framework considers both soil friction and cohesion, soil arching effects and shear stress between adjacent differential elements. The solution obtained is validated against experimental data and FELA results. Through parametric studies, the effects on the active earth pressure of the aspect ratio, soil friction, soil cohesion and wall–soil interface roughness are examined. To facilitate the use of the proposed framework in design, a modified active earth pressure coefficient and an application height of active thrust are provided. [ABSTRACT FROM AUTHOR]

Currently, the use of underground automatic car parks is becoming increasingly popular in Bangkok as it can help maximize space usage without ramps. However, an automatic system requires large openings in the basement slab, resulting in the slab possibly having insufficient axial capacity. This paper focused on one of the latest underground automatic car park construction projects in Bangkok's city center, True Digital Park, which comprises a total of four basements with a 13.20 m maximum excavation depth, including mat foundation and lean concrete. An 800mm-thick diaphragm wall (D-wall) was proposed to serve as a soil-retaining structure with 3 layers of full-temporary bracing. The Finite Element Method (FEM) with the Mohr-Coulomb soil model was employed for the D-wall design and horizontal movement prediction, and the actual construction of the basement and building have since been completed. The field performance of the D-wall construction was evaluated through horizontal movement using installed inclinometers. During every stage of construction, including soil excavation and bracing installation, horizontal displacement was monitored carefully and strictly controlled to minimize the D-wall movement. The monitoring results showed suitable agreement with the FEM analysis. However, movement of the retaining wall was detected during upward construction, even though the basement was fully cast, suggesting insufficient axial basement slab capacity as well as care and control for similar projects. This article describes the construction and monitoring of the project together with field performance results. [ABSTRACT FROM AUTHOR]

This paper introduces a new retaining structure, multi-step cantilever retaining walls pulled locally with geogrids, which has advantages of light weight, quick installation and good applicability for high fill earthworks. Considering log-spiral rotation failure mechanism passing by the heel of the lowest wall members as well as pull-out failure and tensile rupture of the flexible reinforcements, an analytical procedure for seismic overall stability of the retained embankment is proposed based on the upper-bound limit analysis method combined with pseudo static approach. Analysis results of a practical example show that the proposed safety factor and critical slip surface are identical with those by numerical simulation method via FLAC3D. The safety factor increases approximately linearly with the ultimate tension force and the number of reinforcements and nonlinearly with the length of reinforcements within a certain range. Horizontal seismic force has noticeable effect on the slope stability, and vertical seismic effect becomes significant under high horizontal acceleration coefficient. The safety factor is decreasing and the critical slip surface develops obviously towards the embankment exterior as the total number of vertical wall members increases. Besides, the distribution width and setback distance from the walls of the strip surcharge have certain effects on the retained slope stability. [ABSTRACT FROM AUTHOR]

Geotechnical engineers are faced with great uncertainty with regard to the stability design of soil structures such as retaining walls, foundations, and slope stability. Instead of using a deterministic approach by replacing the design parameter with a single mean number, Monte Carlo simulations could be used to provide better decisions by considering all possible outcomes under parametric uncertainty. This paper studies probabilistic failures of classical passive trapdoors in shallow depths with spatially random soils. The effects of soil strength variability are investigated for various spatial correlation lengths and trapdoor depths using the latest adaptive finite-element upper-bound limit analysis with second-order cone programming. In addition, probabilistic stability results are compared with those published in renowned literature, and a comprehensive probability of design failure (PF) charts is developed for a practical range of deterministic factors of safety. The extensive results reported in this paper would be of great interest to engineering practitioners because better decisions can be made in the design process and design confidence improved. [ABSTRACT FROM AUTHOR]

As the most common geological disaster problem in mines, slope geological disasters have become a focus of research, along with the difficulty of mine safety and ecological environment protection together with the ecological restoration of open-pit mines. At present, a large number of slope-retaining wall structures lack research on safety monitoring, real-time acquisition, and intelligent early warning. Therefore, this paper combines cement-modified loess with gravity retaining wall structures and puts forward a new type of greening gravity retaining wall structure. From the perspective of "the Internet of Things + construction", a video monitoring system is established to monitor the retaining wall structure in real time. Finally, based on video image processing technology, the deformation of the retaining wall surface is identified and the inclination angle of the wall surface is calculated, so as to improve the real-time and intelligent monitoring of the new greening gravity retaining wall. The results show that the new greening gravity retaining wall based on video monitoring proposed in this paper has the characteristics of a gravity retaining wall and ecological retaining wall, which are conducive to improving the real-time and intelligent monitoring of the new greening gravity retaining wall. Cement-modified loess is used as the planting matrix, and the cement mixing ratio should not exceed 10%. Considering the requirements of economy and shear strength, the cement mixing ratio should be selected from 5% to 12%. [ABSTRACT FROM AUTHOR]

A reliable assessment of earthquake-induced permanent displacements is a fundamental step for both displacement-based and force-based methods applied to the seismic design of embedded anchored walls. Acceleration reduction factors recommended by the codes for a force-based design of these structures derive from parametric studies of the performance of gravity walls or slopes. This may lead to either conservative or unconservative results and is certainly misleading from the point of view of the physics of the problem. Based on the results of an extensive numerical study, this work clarifies the mechanisms by which anchored walls accumulate permanent displacements during earthquakes, showing that full mobilization of soil passive strength requires displacements of the order ur/H≈1%–2% , making the assumption of rigid-perfectly plastic behavior of the system unsuitable. Moreover, both the critical acceleration and the pattern of final displacements depend on the plastic mechanism effectively activated within the soil-wall-anchor system. The issue of the proper choice of performance factors to be used in a force-based design of anchored walls is also addressed, and a new method is outlined for a preliminary calculation of the permanent displacements of the wall. Finally, the paper critically reviews two methods recently proposed in the literature to compute earthquake-induced wall displacements. All three methods account for the soil-wall system nonlinearity and hardening during the earthquake. The results discussed herein, together with the complementary work presented by the same authors in a companion paper, provide a thorough conceptual framework for the performance-based seismic design of anchored walls. [ABSTRACT FROM AUTHOR]

This paper proposes a prediction model based on the mobilizable strength design method with an equilibrium model to predict the deflection of an embedded cantilever retaining wall in sand. The variation in the location of the pivot point within the retaining wall and the sand dilation are considered. Based on the stress–strain relationships obtained by triaxial tests, the designer can determine a specific shear strain and corresponding mobilized earth pressure for the retaining wall to achieve a global equilibrium. Then, the wall deflection, including rotation and flexure, can be derived. The locations of the pivot points obtained by this method are compared with the results predicted by the minimization approach. Finally, the prediction precision is validated via centrifuge tests and numerical model data published in prior investigations. [ABSTRACT FROM AUTHOR]

This paper focuses on the design as well as on the experimental and numerical validations of the mechanical behavior of a precast ultra-high performance fibre reinforced concrete (UHPFRC) retaining walls. The design, made in accordance with the Canadian Highway Bridge Design Code (CSA S6, 2019), led to the fabrication of a full-scale UHPFRC retaining wall with 3% fibre content which had dimensions of 3 m in height, 2 m in length, 2 m in width, with two vertical and horizontal stiffeners, and very thin vertical and horizontal panels of 40 and 65 mm, respectively. The experimental tests showed that the UHPFRC retaining wall exceeded by 42% the ultimate limit state (ULS) design factored bending moment and showed a very ductile behavior under flexural loading. At service limit state (SLS), the retaining wall had maximum crack opening between 0.15 and 0.28 mm, and a maximum lateral displacement of 4 mm. The finite-element model developed for the application captured accurately the flexural behavior of the UHPFRC retaining wall and was used later in parametric studies to optimize the design. The retaining wall optimal design includes UHPFRC with 3% fibre content and stiffeners with variable cross-section which allows volume reductions of 73% for concrete and 86% for rebars in comparison to the conventional reinforced concrete design. [ABSTRACT FROM AUTHOR]

Geosynthetics have increasingly been applied to geotechnical engineering works due to their numerous advantages, including cost-effectiveness and their significant role in sustainable development. When geosynthetics are used as reinforcement in earth structures, such as embankments, retaining walls and bridge abutments, soil–geosynthetic interface shear behavior is a critical parameter involved in the design. This paper presents a series of monotonic and cyclic/post-cyclic pullout tests carried out to examine the apparatus scale effect on the pullout response of a geogrid embedded in two different soils. To assess the small-scale equipment feasibility, comparisons were made between pullout test parameters derived from small- and large-scale equipment. The test results indicate that, under a low confining stress of 25 kPa, using a smaller-sized apparatus results in lower values of geogrid pullout resistance and maximum mobilized shear stress, but higher values of confined tensile stiffness at low strains. On the other hand, as the confining stress increases (i.e., 50 kPa and 100 kPa), the difference between the results becomes less significant and similar trends are observed regardless of the equipment type. Adopting small-scale equipment enables obtaining soil–reinforcement interaction parameters using test procedures that are less time-consuming than those associated with large-scale pullout tests. However, proper scale effect correction factors may be considered for more consistent estimates of the interface strength parameters under low normal stress values. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized framework to estimate the seismic active earth thrust on rigid retaining walls with unsaturated backfill. A novel suction stress-dependent approach was developed to compute the horizontal and vertical seismic acceleration profiles within the backfill. The framework applies the limit equilibrium method with a log-spiral failure surface and considers the influence of suction-stress through the effective stress approach. A detailed validation of the proposed framework is conducted by comparing it with well-established solutions reported in previous studies showing a satisfactory agreement. Validation was performed for the cases of static loading with suction and seismic loading without suction because of the unavailability of the data for the combined case. The influence of suction on the seismic active earth thrust for different soil types and environmental conditions is presented together with other parameters including wall height, soil friction angle, frequency of input excitation, and horizontal and vertical seismic acceleration coefficients. [ABSTRACT FROM AUTHOR]

National and International road networks are made of structures and infrastructures that often exhibit poor performance due to a lack of maintenance. In this context, Italy recently renewed the legislation regarding existing infrastructure analysis to support knowledge and facilitate a homogeneous data acquisition process. Thus a key component of the process consists of the visual inspection protocols complemented by physical and mechanical measures. This applies to all the structures built for the road network operation, including those classified as geotechnical whose deterioration is often neglected or appropriately surveyed. Along with the definition of a data form for collecting datasets on these aspects, a relevant aspect of the process is the implementation of a collaborative environment for the information management and analysis systems supporting the interested parties in the field. The paper reports the design of a base geotechnical inspection form for Retaining Wall and illustrates some aspects of its implementation in a digital environment. Mixed Reality techniques in combination with web‐based tools for data collection are investigated to increase the feasibility and reliability of the visual inspection of existing road networks. [ABSTRACT FROM AUTHOR]

Mechanically stabilized earth (MSE) walls are recognized for their cost-effectiveness and superior performance as earth-retaining structures. The integration of internally reinforced walls has transformed soil preservation practices, garnering significant attention from the global technical community. The construction method of MSE walls has recently gained widespread popularity, likely due to its cost efficiency and simplicity compared to traditional externally reinforced walls. This paper provides a comprehensive review of MSE walls, including their historical development, aesthetics, benefits, drawbacks, factors influencing lateral displacements and stress responses, and the concept of the MSE wall system. Key approaches for analyzing seismic soil–structure interaction (SSI) issues are emphasized, investigating the dynamic interaction between the structure and soil through various research methodologies. This study incorporates multiple publications, offering an in-depth review of the current state of dynamic SSI studies considering surrounding structures. The findings emphasize the significant sensitivity of the dynamic behavior of mechanically stabilized earth (MSE) walls to soil–structure interaction, highlighting the necessity for continuous research in this area. The paper identifies research gaps and proposes future directions to enhance MSE wall design and application, facilitating further advancements in earth-retaining structures. [ABSTRACT FROM AUTHOR]

The article announces the award-winning papers published in "Geotechnical Engineering" in 2010, including a paper by H. Roscoe and D. Twine on design and performance of retaining walls for the Crampton Prize and a paper on track displacement and energy loss in a railway embankment by M. Hendry, D. A. Hughes and L. Barbour for the John Mitchell Medal prize.

The failure mechanism of MSE (mechanically stabilized earth) walls was studied via numerical analysis with the finite element strength reduction method, which was verified as an effective technique by simulating the experimental results reported in previous papers. The finite element program was applied to explore the effects of reinforcement, geometry, and seismic parameters on failure mechanism control at the design stage of MSE walls to avoid the unavoidable errors experienced in common numerical analysis caused by the assumptions of the failure mode and complex input parameters. The research parameters included the wall height, length, and spacing of the geogrid-reinforced retaining wall and seismic load. The results indicated that the wall height and reinforcement length play a major role in failure mode change. When the reinforcement length is less than 2 m, overturning failure could occur, which was unrelated to the other parameters in all cases studied in this paper. In this paper, the parametric study results were presented by evaluating the critical reinforcement length, generating the failure surface pattern, and summarizing design recommendation. [ABSTRACT FROM AUTHOR]

The study presents state-of-the-art requirements verification process for the prediction of the stability of the multi-staged deep excavation in submerged soft soil retained by stell sheet pile walls structures applied at the development of elasto-plastic finite element calculation method performed from Cast3M and Plaxis FE codes. Optimization numerical calculation results are proposed for retained walls design and construction on the basis of the horizontal displacement, earth and water pressures measurements. The transformation of the geometry and stiffness of the stell sheet pile walls to the retaining walls of an equivalent bending stiffness on the one hand and regular geometric shapes allowed in this paper to overcome the difficulties of modelling these stell sheet pile walls in 2D with irregular shapes. The horizontal deflection of the wall, the vertical displacement behind the walls, and the settlement of the excavation bottom are given. They have been compared by those obtained by various authors around the world. The results of this approach are satisfactory in view of the horizontal displacement curves obtained on the stell sheet pile walls compared by the measures. [ABSTRACT FROM AUTHOR]

Chiaia station is one of the art stations of Line 6 of the Naples underground network; it was constructed in a 50-m-deep excavation, a few meters from historic buildings and 4.5 m from the main façade of a sixteenth-century Basilica. The excavation, carried out partially in loose to medium dense sands overlying the soft rock formation of Neapolitan Yellow Tuff (NYT), was supported by a retaining wall made of contiguous bored piles braced with internal struts and prestressed ground anchors. The excavation sequence was quite complex due to archeological findings and to the presence of anthropic cavities used over the centuries to quarry NYT blocks. One of the key goals of the design was to limit movements around the shaft to prevent damage in the historical buildings. Long-term monitoring data obtained during nearly 9 years confirm the success of the overall construction process. A rather complex three-dimensional (3D) finite-element model with constitutive relationships for both the upper sandy layers and the soft rock is presented in the paper; this model was adopted to back-analyze the data from the monitoring and explore the influence of some of the key features of the case study. The role of the building bending and shear stiffness, of the soft rock stiffness, and of further apparently minor issues—such as the seepage and the ground anchors' prestress—were investigated and discussed with the support of the model calculations. Observed settlements at the end of the excavation were in the range 10–15 mm, and in the long term they increased by 20%–50% to as much as 20 mm. The deflection ratios were very small, in the range 0.05‰–0.15‰ , and no visible damages to the buildings were recorded. These values were reproduced by the finite-element model only after the introduction of the relevant building stiffness. [ABSTRACT FROM AUTHOR]

This paper presents a safety tool to assess the risk of road blockage during and after emergency situations, mainly due to earthquakes. This method can be used by public authorities to calculate the risk of road paths prone to blockage in case of seismic events. Typological classes of elements interfering with roads, such as unreinforced masonry and reinforced concrete buildings, unreinforced masonry and reinforced concrete bridges, retaining walls, and slopes, are considered. The mean annual frequency (MAF) of exceedance of a blockage limit state is calculated for a path with redundant road segments considering fragility curves from the literature. A practical example is presented for Amatrice, a town in Central Italy hit by the 2016 earthquake. After verifying that the MAF of exceedance demand is lower than the capacity for two roads, a strengthening solution is assumed for two buildings in the path, resulting in a reduction by more than 50% of the MAF demand. For a higher safety level, a bypass is proposed obtaining a demand/capacity ratios four orders of magnitude lower than that obtained with strengthening solutions, highlighting and quantifying the beneficial effect of removing vulnerable structures along the path. [ABSTRACT FROM AUTHOR]

A two-stage cantilever retaining wall is composed of two single-stage cantilever retaining walls, which are stacked up and down. The structure not only has the advantages of a single-stage retaining wall, but also compensates for the shortcomings of the height limit of the single-stage retaining wall; therefore, it has been gradually applied in projects. Based on the actual project of Zhongwei-Lanzhou Passenger Dedicated Line into Lanzhou Hub, this paper studies the influence of the construction of new cantilever retaining wall and the filling of subgrade on the deformation and earth pressure of the new cantilever wall and the existing cantilever wall by means of field test and numerical simulation. The results show that with an increase in the filling height after the new cantilever wall (upper wall), the horizontal displacement of the top of the upper and lower walls increased nonlinearly. The displacement direction of the upper wall was the filling direction, and that of the lower wall was the deviation from the filling direction. The higher the filling height, the greater is the displacement. With an increase in the filling height, the earth pressure behind the upper wall increases gradually along the wall height and decreases slightly to the bottom of the wall, which is approximately a linear distribution. The earth pressure behind the existing cantilever wall first increases along the wall height and gradually decreases after reaching a certain depth, but the earth pressure of the lower wall does not increase significantly with an increase in the filling height behind the upper wall. The slope failure mode is the overall sliding failure of the retaining wall together with the fill soil. The sliding surface passed through the lower edge of the lower wall heel and was similar to an arc shape. The stability of the two-stage cantilever retaining wall was better than that of a single-stage retaining wall. Finally, a calculation method for the overall stability and earth pressure of the existing two-stage cantilever retaining wall was proposed. [ABSTRACT FROM AUTHOR]

This paper investigates the sliding surface failure characteristics, earth pressure distribution law and stability safety factor of inverted T-type retaining wall by using the finite element limit analysis software OptumG2, the effects of width of wall heel plate, width of wall toe plate, thickness of bottom plate, soil–wall interface friction angle, soil cohesion and soil internal friction angle of filling on the failure characteristics of sliding surface, the earth pressure distribution law and stability safety factor of retaining walls are analyzed, The stability safety factor of the retaining wall showed a gradually increasing trend as the width of wall heel plate and wall toe plate increased; as the bottom plate thickness increases, the stability safety factor of the retaining wall gradually increases; as the soil-wall interface element reduction coefficient rises, that is, the internal friction angle of the soil-wall gradually increases to the soil internal friction angle, the stability safety factor of the retaining wall gradually increases; as the soil cohesion and internal friction angle increase, the stability safety factor of the retaining wall progressively increases. The safety factor of retaining wall increases by 0.45 for every 0.5m increase in the width of the wall heel plate; the safety factor of the retaining wall increases by 0.29 when the width of the wall toe plate increases by 0.5m; for every 0.5m increase in the width of wall plate thickness, the safety factor of the retaining wall is increased by 0.62; for every 0.25 increase in soil-wall interface element reduction coefficient, the safety factor of the retaining wall increases by 0.29; for every increase of 5KPa in soil cohesion, the safety factor of the retaining wall increased by 1.16; for every 5° increases in soil internal friction angle, the safety factor of retaining wall increases by 0.6. The research is significant for studying the failure laws and stability of retaining walls and providing references for retaining wall design. [ABSTRACT FROM AUTHOR]

The occurrence of slope instability disasters seriously endangers the safety of people's lives and property in China. Therefore, it is essential to study the slope instability process and the interaction between soil and retaining walls. In this paper, the smoothed-particle hydrodynamics (SPH) method, based on the elastoplastic constitutive model of rock and soil, was used to simulate the entire process of slope instability and the interaction between soil and retaining walls. The model, based on the classical elastic–plastic theory, includes linear elastic deformation and plastic deformation following the non-associated flow rule under the Drucker–Prager (DP) yield criterion. By considering the plastic characteristics of geotechnical materials, this method can accurately simulate the slope movement process. The model was established, calculated, and compared with a slope example, thus verifying its feasibility. Furthermore, the motion response of the retaining wall under different conditions was studied, which provides a new numerical simulation platform for the stability checking of the retaining wall and motion analysis after the interaction between the retaining wall and slope soil. [ABSTRACT FROM AUTHOR]

This paper develops predictive models for optimal dimensions that minimize the construction cost associated with reinforced concrete retaining walls. Random Forest, Extreme Gradient Boosting (XGBoost), Categorical Gradient Boosting (CatBoost), and Light Gradient Boosting Machine (LightGBM) algorithms were applied to obtain the predictive models. Predictive models were trained using a comprehensive dataset, which was generated using the Harmony Search (HS) algorithm. Each data sample in this database consists of a unique combination of the soil density, friction angle, ultimate bearing pressure, surcharge, the unit cost of concrete, and six different dimensions that describe an optimal retaining wall geometry. The influence of these design features on the optimal dimensioning and their interdependence are explained and visualized using the SHapley Additive exPlanations (SHAP) algorithm. The prediction accuracy of the used ensemble learning methods is evaluated with different metrics of accuracy such as the coefficient of determination, root mean square error, and mean absolute error. Comparing predicted and actual optimal dimensions on a test set showed that an R 2 score of 0.99 could be achieved. In terms of computational speed, the LightGBM algorithm was found to be the fastest, with an average execution speed of 6.17 s for the training and testing of the model. On the other hand, the highest accuracy could be achieved by the CatBoost algorithm. The availability of open-source machine learning algorithms and high-quality datasets makes it possible for designers to supplement traditional design procedures with newly developed machine learning techniques. The novel methodology proposed in this paper aims at producing larger datasets, thereby increasing the applicability and accuracy of machine learning algorithms in relation to optimal dimensioning of structures. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a landslide's remediation conducted on the basis of research and testing of samples, and list those measures that will help to remediate the landslide or partially mitigate its further effects. These measures include: closing cracks, collecting and draining surface water from landslides, terrain planning, making supports from stone materials, drainage trenches, draining water from traffic areas, repairing water supply and sewerage systems, and establishing monitoring. The paper analyzes the phenomenon of instability and its causes, and presents the results of research at site in question before and after the remediation of instability. The geological profile and remediation methods will be determined after the presentation of the results. [ABSTRACT FROM AUTHOR]

The horizontal displacement values experienced by the isolation layer of base-isolated buildings can exceed the allowable range and cause failures during the rare or very-rare earthquakes. Excessive horizontal displacements of the isolation layer may cause collisions between the building and retaining walls of the isolation ditch and even cause the collapse of the isolated building. This paper proposes a cost-effective, easy-to-build, passive bumper device, called Flexible Limit Protective Device (FLPD) in order to act as shock-absorbers. Through numerical simulations and experiments, the nonlinear behavior of the FLPD is investigated. Subsequently, through structural simulations, the effectiveness of using FLPDs is studied. The elitist non-dominated sorting genetic algorithm (NSGA-II) is used to optimize the design of FLPDs, and the response of structures equipped with optimized FLPDs are simulated numerically. The results indicate that proposed optimized FLPDs can effectively work as shock-absorbers for base-isolated structures. This paper can provide a guideline for the design of shock-absorbers. [ABSTRACT FROM AUTHOR]

This paper presents the case histories of deep excavation for the basements of two projects using 11 retaining walls supported by stabilizing berms. Most of the case studies reported in the literature are confined to the use of stabilizing berms to support retaining walls for deep excavation in firm overconsolidated clays but not soft normally consolidated clays. This paper reviews the performance of 11 retaining walls supported by stabilizing berms for deep excavation in soft normally consolidated clays. Only four of these 11 stabilizing berm-supported retaining walls performed satisfactorily while the other seven performed dismally. The larger horizontal deflection of retaining walls embedded in soft normally consolidated clays as compared to overconsolidated clays is caused by creep of soft normally consolidated clays. The effect of creep of soft normally consolidated clays in deep excavation is not well understood. Based on the case study of an excavation of 8.3 m (27.2 ft) deep, an empirical relationship between the retaining wall deflection due to creep of soft clays and the total thickness of soft clays is established. The present study highlights the need to check the slope stability of the stabilizing berms in soft normally consolidated clays during excavation. This has never been thought to be necessary for stabilizing berms supporting retaining walls in overconsolidated clays for deep basement construction. [ABSTRACT FROM AUTHOR]

The safe thickness of concrete retaining walls for curtain grouting on tunnel faces is an essential factor related to tunnel safety and grouting effects. In this research, the concrete retaining wall was simplified into a standard rectangular slab structure. The Rankine active earth pressure theory and the plastic hinge theory were used to analyze the lateral force of the concrete retaining wall. By deriving the safety-thickness equation of the concrete retaining wall, a quantitative criterion that can display the mechanism of the concrete retaining wall was obtained. The traditional empirical formula and Kalmykov formula had a particular connection with the method in this paper in determining the safe thickness of the concrete retaining wall. This was negatively related to the compressive (tensile) strength of the concrete and the groundwater level and positively associated with the buried depth of the tunnel. The conversion relationship between the traditional empirical formula and the theoretical formula was established, and the exact solution formula for the value of safety coefficient K0 was given. Finally, the rationality of the theoretical formula was verified by a field test, in novel work that provides a reference for similar projects. [ABSTRACT FROM AUTHOR]

This paper investigates the active earth pressure of inverted T-type retaining walls under rotational mode using a slip-line method for the typical failure mechanism simulated with adaptive finite element software. Considering the influence of the heel bottom plate, the slip-line field calculation models for the inverted T-type retaining wall with long and short heels were established, respectively. The limit equilibrium method and the finite difference method were used to solve the stress state of each point. The earth pressure acting on the stem and the imaginary wall can be obtained by converting the boundary conditions. The proposed method was verified by comparison with results from the finite element method and some existing theoretical solutions. In addition, several extensive parametric studies have been conducted to investigate the effects of heel length and interface strength. The results show that increasing the heel length and interface strength is beneficial for maintaining backfill integrity and reducing earth pressure against the stem and imaginary wall. [ABSTRACT FROM AUTHOR]

This paper introduces the Goodman contact element based on the virtual element method framework. Since the virtual element method can calculate polygonal elements with any number of nodes, the limitation of mesh matching of the contact part required by the Goodman contact element is overcome by adding nodes to the contact element. Combine the virtual element method with the Goodman contact element to enable the Goodman contact element to solve practical problems in geotechnical engineering. In this paper, first, we derive the elastoplastic virtual element equations, and then, the Goodman contact stiffness matrix based on the virtual element method is calculated. Finally, several numerical examples are shown. In numerical models, the sensitivity of the virtual element method to mesh distortion is studied. We also investigate the shape sensitivity of the algorithm and the convergence of the Voronoi element through several frictionless contact examples. And then, the contact examples under friction state and elastic–plastic constitutive law are carried out. Finally, the contact force between soil and wall under the non-matching mesh in the gravity retaining wall commonly used in geotechnical engineering is presented. [ABSTRACT FROM AUTHOR]

This work aims to highlight gravity segmental retaining walls with their varied advantages. The paper investigates the dynamic behavior analysis of segmental retaining walls. The stability analysis is conducted on the basis of a pseudo-static Mononobe-Okabe theory that provides safety factors against sliding and overturning failure. The results demonstrate that the crucial safety factor of internal stability is the safety factor against overturning. Moreover, the positive wall inclination angle contributes to an improvement in the stability of the segmental retaining walls and the effect of the vertical seismic coefficient on the stability can be disregarding. Finally, a new equation is proposed for the elementary design of the segmental retaining walls. [ABSTRACT FROM AUTHOR]

The estimation of earth pressure is crucial in the design of retaining structures. The evaluation of vertical retaining walls has been well studied within the framework of the differential flat element method in prior investigations, in which the vertical stress and maximum principal stress are assumed to be uniformly distributed. Inclined retaining walls have been successfully adopted in excavation engineering. Due to the inclination of retaining walls, the maximum principal stress direction rotates approximately parallel to the inclined wall back, which affects the active earth pressure on the walls. This paper provides an analytical solution to evaluate the active earth pressure on inclined retaining walls. A numerical model is first established to analyze the characteristics of the principal stresses and vertical stress distribution of soil behind walls with various inclination angles. An idealized vertical stress field containing two zones is developed, and a hyperbolic function is proposed to illustrate the distribution of vertical stress at various depths. Subsequently, the relationship between the nonuniform characteristics of the vertical stress and normal stress acting on a differential flat element is established based on a circular stress trajectory. The active earth pressure along the inclined wall is then obtained based on the balance of the forces on the differential elements. The predicted data from the proposed analytical solution are compared with the previous experimental, numerical, and theoretical results with excellent agreement, demonstrating the accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Deep excavations in urban areas are highly hazardous due to extensive settling of the surrounding soil, which can lead to the failure of retaining wall systems and the consequent collapse of adjoining properties. The retaining wall and bracing system are important for completing deep excavations for a basement building project. This paper evaluates the performance of an alternative, innovative, low-cost pile-supported bracing system (PSBS) method during excavation for two-level basement construction. Assessed PSBS performance in terms of ground settlement, lateral movement of supporting systems, schedule, and cost comparison. The PSBS excavation method was designed and then implemented to construct a two-level basement using the bottom-up method. The total station was utilized to monitor three-dimensionally, like the adjacent school building, ground surface settlement, and lateral movement of supporting systems. A schedule and cost comparison were performed using internal bracing and the PSBS technique. The recorded filed data was analysed, and it found that the lateral movement of the support system, adjacent building, and ground settlement is within the allowable limit. According to the estimated results, the PSBS method reduces construction time by 272 days compared to the internal bracing system. The PSBS approach is also less expensive than internal bracing for a two-level basement. [ABSTRACT FROM AUTHOR]

A retaining wall is generally provided to protect the unsupported soil mass. For designing the retaining walls, pseudostatic methods are well established for the computation of soil thrust and coefficients of earth pressure in seismic conditions. In the present paper, the coefficients of active earth pressure due to soil wedge and strip load present on the cohesionless backfill of the retaining wall are determined by considering the pseudostatic method for seismic conditions and using the kinematic limit approach. The proposed solution considers the presence of soil–wall friction angle, as well as the size and distance of the strip load. Closed-form solutions are provided to calculate the coefficients of active earth pressure. It can be observed that for the strip load of magnitude 30 kPa and width 1.65 m situated close to the retaining wall, the coefficient of earth pressure due to soil wedge decreases by 10.05% compared with the absence of the strip load. The proposed method has been compared with the investigations available in the literature. The influence of the magnitude of the strip load and its distance from the wall is thoroughly investigated and presented with different parameters. [ABSTRACT FROM AUTHOR]

Design guidelines for geosynthetic-reinforced soil (GRS) walls in a tiered configuration are often limited to two tiers with zero batter. To facilitate rational expansion of current design, this paper extends the current top-down procedure, based on limit equilibrium analysis, from single GRS walls to multitiered walls. For a given factor of safety, the required reinforcement tension distribution and connection load are determined for each reinforcement layer. The approach considers the impact of potential compound failures. Parametric studies are conducted to investigate the influences of backfill soil, wall geometry (i.e., wall batter, number of tiers, and offset distance), and reinforcement layout. The results demonstrate quantitively that increasing the internal friction angle of backfill soil, wall batter, number of tiers, and offset distance reduce the required maximum tension. The tiered configuration in GRS walls leads to localized increase in connection load at the toe elevation of each tier. Using close reinforcement spacing could significantly reduce the connection load. The critical offset distance is realized when the reinforcement in each tier acts internally independent of others. Its value decreases with increasing the internal friction angle of backfill soil, wall batter, and number of tiers. The observations in this study are significant in the context of optimal design of multitiered GRS walls. [ABSTRACT FROM AUTHOR]

An accurate estimation of earth pressure on retaining walls is imperative to achieving its design. This paper presents an analytical method framework that considers the effect of plant transpiration relative to the traditional calculation approaches. Specifically, a closed-form solution for one-dimensional steady unsaturated flow considering plant transpiration is incorporated into a representation of effective stress to obtain the changes in matric suction, and effective stress. The representations are used to extend Hooke's law and Rankine's earth pressure theory to determine at-rest, active, and passive earth pressures. Subsequently, the analytical method is used in a series of analysis case studies on the influence of root architecture types, transpiration rates, and soil types on earth pressure, to reveal that it can rapidly obtain the earth pressure. Notably, the effect of plant transpiration on earth pressure is significant. Furthermore, it is found that soil types and transpiration rates have a larger influence than root architecture types. Collectively, the research not only reveals the effect of plant on earth pressure for retaining wall, but also provides a theoretical basis for further exploration of the contribution of plants to the stability of retaining wall. [ABSTRACT FROM AUTHOR]

Retaining walls are a part of the geotechnical construction industry for the support of structures from soil erosion. Granular materials are conventionally used as backfill behind retaining walls. Instead of the conventional compacted granular fill, other industrial by-products are also used nowadays. The utilisation of these industrial by-products for Civil engineering applications helps to build a sustainable environment by reducing the waste depositions. In this paper, an experimental study was conducted to evaluate the properties of coal ash-based Controlled Low Strength Materials (CLSM) for backfill applications. The properties of pond ash-based CLSM mixes were studied to identify the effectiveness in utilising CLSM for backfill applications. Further, numerical analysis using PLAXIS 2D was carried out to evaluate the stresses and displacements developed in retaining walls for different backfilling materials. It was observed that CLSM mixes exhibit the properties required for utilising it as a backfill material. The stresses and deformations developed in situations where CLSM was used were found to be negligible compared to the normal compacted backfill materials. Thus, the studies on CLSM mixes showed that pond ash can be used as a replacement to natural aggregates which can be used as a backfill for retaining wall applications. [ABSTRACT FROM AUTHOR]

Back analysis is the most common method to study landslide movements after the event, and it allows us to understand how a landslide evolved along the slope. This paper presents the back-analysis of the Pomarico landslide (Basilicata, Italy) that occurred on January 25th, 2019, on the southwestern slope of the Pomarico hill. The landslide, of rotational clayey retrogressive type—planar sliding, evolved in different phases until it caused a paroxysmal movement in the early afternoon on January 29th, 2019. The landslide caused the collapse of a bulkhead (built at the end of the twentieth century) and of some buildings along the village's main road. In this paper, a multi-layer back-analysis study is presented, based on the limit equilibrium model (LEM), applying the solution proposed by Morgenstern and Price in Geotechnique 15(1):79–93zh, (1965) and implemented in the freeware software SSAP 2010. The analysis allowed the reconstruction of the entire landslide evolution, using geotechnical parameters obtained from both laboratory and in situ tests, and data from the literature. The application of multilayer back-analysis made it possible to avoid the homogenisation of the layers, modelling the event according to the real conditions present on the slope. The use of the SSAP software made it possible to curb the problem related to the theoretical limitation of the shape of the rupture surfaces, by evaluating independently the friction angle locally and by discarding all those surfaces, which, due to this problem, presented a non-reliable factor of safety (FS) value. The modelling revealed a slope that is highly unstable as the height of the water table changes. The FS calculated under water table conditions close to ground level was less than 1 (FS = 0.98), simulating the first landslide movement (November 2018). The subsequent model reconstructed the critical surface responsible for the January 2019 movement and calculated the FS present on the slope (FS = 1.01). Eventually, the paroxysmal event on January 29th, 2019, was modelled, returning an FS of 0.83, and a sliding surface that sets below the bulkhead, causing its failure. Furthermore, the modelling of the slope in the presence of adequate retaining structures demonstrated the (non-) effectiveness of the retaining wall system represented by the bulkhead. The proposed method of analysis suggests further applications in similar complex multi-layer soil-structure interaction scenarios. [ABSTRACT FROM AUTHOR]

Geosynthetics have been commonly used for the construction of civil engineering structures such as retaining wall, road and railways, coastal protection, soft ground improvement work, and landfill systems since the 1960s. In the past 40 years, the development of polymer materials has helped to prolong the life of geosynthetics. In terms of the practical use of geosynthetics, engineers must understand their appropriate application. The first part of this paper provides a basic description of geosynthetics, including their types, components, and functions. The second part deals with the geosynthetics used as filters. This part briefly presents the mechanism of filtration, the factors affecting the durability of geotextile filters, design concepts, laboratory tests, and case studies. The third part of the study covers the use of geosynthetics for stabilisation. Its mechanism was explained separately for geogrids and for geocells. Several examples of applications with geosynthetics intended for the stabilisation function are described in the last part of this paper. [ABSTRACT FROM AUTHOR]