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A rigorous solution aimed at accounting for the superposition and flow rule assumptions in the assessment of the bearing capacity of shallow strip footings under plane strain conditions has been developed using the method of characteristics and the finite element method. With reference to the Hill and Prandtl failure mechanisms, a bearing capacity factor Nγq and a superposition corrective coefficient μ that allow to directly obtain the actual bearing capacity of shallow strip foundations have been proposed. The geometry of the plastic volume involved in the failure mechanism has been also investigated, highlighting the influence of the superposition and flow rule assumptions. Starting from the numerical results obtained using the method of characteristics, several empirical relationships have been proposed for an accurate estimate of Nγq and μ as well as for the lateral extension and depth of the plastic volume. The accuracy of the numerical results has been checked through finite element analyses under the assumption of associated and non-associated flow rule showing that the proposed superposition corrective coefficient μ is not influenced by the flow rule assumption. Thus, a general bearing capacity equation for shallow strip footings has been provided which accounts for superposition approximation and non-associated flow rule. [ABSTRACT FROM AUTHOR]

The bearing capacity of shallow foundations on geocell-reinforced sand (GRS) depends not only on the soil characteristics but also on the geometries and properties of geocell. The geometry characteristics of GRS comprise height, length and cell aperture size of geocell as well as the sand layer thickness engaged between footing and GRS layer. Using the design-of-experiments (DOE) method the trends of bearing capacity ratio (BCR) as a function of selected geometry parameters of geocell are systematically visualized. Furthermore, trends of BCR as a function of geocell-selected geometry parameters are analysed. To this end, the study deploys the response surface methodology (RSM) to identify several configurations of geocell by conducting only twenty-seven laboratory tests. The results show that the DOE-RSM method gives an efficient interpretation of the variable's interaction while it lessens the number of tests. In addition, it has been found that the geocell height is the most influential parameter on BCR of footings on GRS. Moreover, an interaction between geocell aperture size and geocell height is recognised. The results are formulated and compared with the literature, resulting in good agreement. [ABSTRACT FROM AUTHOR]

Soil–rock mixture, a non-homogeneous medium with discrete characteristics, is commonly used in high-fill projects. This study analyzes the impact of rock morphology and distribution on the ultimate bearing capacity and sliding failure surface morphology of soil–rock embankments using the discrete element method (DEM). The results indicate that the embankment's ultimate bearing capacity increases with higher rock content. A larger ultimate bearing capacity is observed when rocks aggregate at the top of the sliding zone and the slope's toe. The influence of rock inclination angle on the ultimate bearing capacity follows this order: 30° > 45° > 60° > 0°. The rotation of block stones mainly occurs in the roadbed's shear zone. This study examines the shear zone morphology of the roadbed influenced by the stone content and spatial distribution of block stones. In this paper, we establish a sliding surface equation that considers the stone content and spatial distribution, providing guidance for assessing roadbed stability using the limit equilibrium method. [ABSTRACT FROM AUTHOR]

Investigations on the changes in pore water pressures and stress during the construction of stiffened deep cement mixing (SDCM) piles are scarce, resulting in an unsatisfactory understanding of the bearing capacity formation process. Thus, this paper presents a preliminary field study to investigate the variation characteristics of pore water pressures, total stress and effective stress during the construction of SDCM piles derived from field tests. In the meantime, cone penetration tests (CPTs) were conducted before and after the construction of SDCM piles. The results show that the variation ranges of pore water pressure, total stress and effective stress of soils around piles decreased with increasing distance between the measuring point and piles when the depths of the measuring points were the same. During the piling process, the effective stress increased by approximately 53–103%, and the pile side frictions increased accordingly, while the tip resistance and side resistance values of soils around piles increased by 27–106% and 2–145%, respectively. Additionally, SDCM piles successively formed different load-bearing components with decreasing bearing capacity along the pile diameter direction, which realized a better bearing efficiency than conventional piles made with homogeneous materials. In essence, they were also the source of significant economic advantages of SDCM piles. Through this study, we expect to provide a reference for further studies on the bearing mechanism of SDCM piles in soft soil regions. [ABSTRACT FROM AUTHOR]

A large number of concrete-filled CFRP steel tube structures are widely used in practical engineering at current. Considering that as a column structure, compressive-shear loading is a more important bearing capacity method. 12 specimens are designed to study the comperssive-shear performance of concrete filled CFRP steel tube. The shear loading- displacement (V-Δ) curves and the collaborative work performance between the steel tube and CFRP are tested. Based on the tests, a numerical simulation method is firstly proposed to estimate the compressive-shear performance of concrete-filled CFRP steel tube stub column, and then validated against the representative tests results.Parametric study is conducted to explore the influence of principle factors on compresive-shear behaviour by verified numerical models. The experimental results show that the steel tube and CFRP can work together. As the axial compression ratio increases, the shear displacement of the specimen is constrained, resulting in increase of bearing capacity. Additionally, the increase of steel ratio, CFRP layers and materials strength for specimens enhance not only the bearing capacity but also the initial stiffness. The simulation results of the established finite element model are in good agreement with the experimental results. Finally, Based on experimental and finite element results, the bearing capacity correlation equation for concrete-filled square CFRP steel tublar stub columns when subjected to compressive-shear loading is presented. [ABSTRACT FROM AUTHOR]

The aim of the paper is to propose design tools for pile groups when vertical and moment loads are applied simultaneously. This is done by presenting a method to derive the exact solution for the failure locus in the generalized force space, including a vertical load and a moment with components along two axes, to employ for capacity requirements which helps to get rid of overconservative assumptions usually adopted in design. Moreover, closed-form solutions for performance-based interaction domains are also provided allowing to detect all the combinations of external loads associated with a given value of settlement and/or rotation of the foundation that is extremely useful when the design is ruled by serviceability requirements. The application of these straightforward formulae provides results which are in very good agreement with the more rigorous solutions derived from a numerical procedure developed ad hoc for the problem at hand. [ABSTRACT FROM AUTHOR]

This study investigates soil–steel composite structures, emphasizing the role of stiffening ribs and geotextile reinforcement through comprehensive numerical modeling. This study presents a two-dimensional finite element analysis (FEA) and compares the influence of stiffening rib and geotextile on the ultimate bearing capacity of the soil–steel composite structures. The results of this study demonstrate a significant enhancement in load capacity. Specifically, a notable 47% improvement was observed with a stiffening rib, and a 26% increase was noted with the use of a single layer of geotextile. Under peak load, the vertical displacement at the crown exceeds the permissible standard for all models except for one model, while bending moments reach their limits, marking a failure mode of composite system considered. Structures with stiffened ribs reach their load capacity due to the creation of a plastic hinge around the shoulder and haunch of the shell. On the other hand, in structures without stiffening ribs, the crown and haunch section of the shell becomes fully plastic under peak load. The maximum axial thrust is shown in geotextile-reinforced structure, reaching 78% of the shell maximum capacity due to compression. Eventually, stiffening rib substantially improves overall load-bearing capacity of the soil–steel composite structures, and geotextile placement in the upper part of the backfill reduces shell deflection due to bending. [ABSTRACT FROM AUTHOR]

This paper addresses the critical gap of uncertainty quantification in existing geotechnical models predicting bearing capacity for shallow foundations on cohesionless soils. The developed Bayesian regression model improves point estimate accuracy by 30% compared to traditional models while introducing a robust method for quantifying prediction uncertainty. Utilizing extensively studied literature data, we demonstrate the model's closed-form structure, allowing the direct calculation of both the most probable bearing capacity and its uncertainty. This transparency distinguishes the proposed model from black-box machine learning alternatives. Furthermore, we illustrate its practical applicability by integrating it into reliability-based design, specifically showcasing its utility in incorporating applied load distributions. In essence, this research enhances predictive accuracy and establishes a comprehensive framework for addressing uncertainty in bearing capacity models, with direct implications for reliability-based design practices. [ABSTRACT FROM AUTHOR]

This paper proposed a theoretical solution to predict the bearing capacity of a new horizontal-vertical (H-V) geogrid reinforced foundation under strip footing, incorporating the key mechanism including the friction and the interlock between soils and the horizontal plane of H-V geogrid, and the confinement of the vertical plane of the H-V geogrid. The input to the equation includes soil properties (e.g., unit weight, soil friction angle, Terzaghi's bearing capacity coefficient) and H-V geogrid properties (e.g., tensile strength, geometry, aperture size, and dimension of the geogrid). The results showed that the theoretical equation accurately predicted the bearing capacity of the H-V geogrid as well as the conventional geogrid-reinforced foundation. Contrary to the traditional geogrid, the vertical component of the H-V geogrid offered effective soil resistance. When the height of the vertical element of the H-V geogrid increases from 0 to 0.04 m, the bearing capacity of the H-V geogrid foundation was increased about 1.44 times compared to the conventional one. When the vertical element spacing is reduced from 1.60 to 1.33 times the width of strip footing, the bearing capacity rise from 1.20 to 2.63 times compared to a traditional geogrid-reinforced foundation. [ABSTRACT FROM AUTHOR]

Evaluating the bearing capacity of strip footing is a classic problem in geotechnical engineering, which has been investigated by many researchers. As the advancement of technology and urbanization, less and less land area can be available for the construction of facilities, which results in that many buildings must be constructed near slopes. The bearing capacity of strip footing constructed near slopes is usually lower than that on flat land. When the soil strength of slopes is not sufficient to support the external loads, it is often necessary to backfill or reinforces the slopes to make the strength of slope meet application requirements. The discontinuity layout optimization (DLO) method is therefore adopted in this paper to investigate the effects of various factors on bearing capacity and failure mechanism of strip footing on inclined multilayered natural slopes. Two conditions, normal slope and backfilled reinforced slope, are considered in the analysis. In addition, the influence of distance between the strip footing and slope, the number of soil layers, the thickness of the interlayer soil layer and earthquake on the unreinforced slope, and the influence of geosynthetic length and burial depth on the reinforced slopes are investigated. Eventually, the results showed that different factors have different impacts on the slope bearing capacity and failure mechanism. [ABSTRACT FROM AUTHOR]

A collection of feed forward neural networks (FNN) for estimating the limit pressure load and the according displacements at limit state of a footing settlement is presented. The training procedure is through supervised learning with error loss function the mean squared error norm. The input dataset is originated from Monte Carlo simulations for a variety of loadings and stochastic uncertainty of the material of the clayey soil domain. The material yield function is the Modified Cam Clay model. The accuracy of the FNN's is in terms of relative error no more than 10 - 5 and this applies to all output variables. Furthermore, the epochs of the training of the FNN's required for construction are found to be small in amount, in the order of magnitude of 90,000, leading to an alleviated data cost and computational expense. The input uncertainty of Karhunen Loeve random field sum appears to provide the most detrimental values for the displacement field of the soil domain. The most unfavorable situation for the displacement field result to limit displacements in the order of magnitude of 0.05 m, that may result to structural collapse if they appear to the founded structure. These series can provide an easy and reliable estimation for the failure of shallow foundation and therefore it can be a useful implement for geotechnical engineering analysis and design. [ABSTRACT FROM AUTHOR]

The bearing capacity of shallow foundation is significantly affected by stratum uncertainty, mainly including geological uncertainty and spatial variability of soil properties. This paper aims to develop a general framework of shallow foundation to characterize the influence of two types of uncertainties on bearing capacity quantitatively. The geological uncertainty is simulated by Markov random field with different borehole schemes. The spatial variability is characterized using random field theory considering variations of the vertical scale of fluctuation. The bearing capacity of shallow foundation analysis is then conducted based on the proposed calculation framework. Borehole data and soil properties collected from Shenzhen Mawan are adopted as an example to illustrate the proposed framework. A reduction factor is developed to reveal the relationship of two category uncertainties on bearing capacity. A contribution rate indicator is defined to quantitatively evaluate the impact of two category uncertainties. Results show that the geological uncertainty greatly influences the calculation results when boreholes are sparse. However, spatial variability dominates in two kinds of uncertainties when having relatively more boreholes. [ABSTRACT FROM AUTHOR]

This paper aims to propose a design method for energy piles using the results of in situ pressuremeter tests. The method is based on the incorporation of thermal effects through a numerical model of cylindrical cavity expansion. Pressuremeter profiles are generated by the numerical model, which represent the limit pressure at different temperature variations. The pile's bearing capacity is, subsequently, determined by following the standard procedure outlined in Eurocode 7 for the pile design, which is based on pressuremeter tests. Thus, relying on pressuremeter curves, the proposed method is enabled to provide the mobilized base resistance, shaft friction and the bearing capacity of an energy pile. In a second phase, a case study of an energy pile located in a clay soil is conducted in order to explain the different steps of the proposed method and to examine the impact of thermal effects on the bearing capacity. The study reveals an increase of the bearing capacity when heating which reaches 3% at Δθ = 40 °C and a decrease of 4% at Δθ = − 40 °C when cooling. This variation is non-linear and asymmetric because the decrease caused by cooling is not fully recovered during heating: A loss of 1% of the bearing capacity is observed. As a result, it is crucial to consider thermal effects in the design of geothermal piles. On the other hand, the proposed method could be a practical approach for engineers to design energy piles. [ABSTRACT FROM AUTHOR]

The essence of the proposed methodology for monitoring the kinetics of damage to a deformed material is to establish a correspondence between micro-, meso-, and macrodamage, and the acoustic emission pulses generated in this case. During the loading process of a product, the recorded pulses are divided into pulse flows of low (H), middle (C), and high (B) energy levels, corresponding to the energy of destruction of structural bonds. By calculating the current values of the partial content of acoustic emission pulses in the H, C, and B clusters generated by micro-, meso-, and macrodamage, and comparing them with the threshold ones established during destruction, the load-bearing capacity current level of a product during loading is determined. Application of the developed methodology for identifying zones of developing damage and assessing the load-bearing capacity of the current state of stringers under loading conditions during interlayer shear tests is considered. [ABSTRACT FROM AUTHOR]

The ongoing refinement of bearing capacity equations remains pivotal in soil mechanics and foundation engineering, reflecting its critical role in ensuring design efficacy and construction safety. This study conducts a thorough evaluation of classical bearing capacity methods—Terzaghi, Meyerhof, Vesic, and Hansen—and methods included in various design standards, such as EN1997:2004, prEN1997:2023, GEO, AASHTO, FHWA, and API. It explores the performance and applicability of these approaches, identifying areas for potential improvement. In response to identified challenges, the paper proposes the integration of a unified depth factor. This new factor is designed to be applicable across all N-terms, providing a more versatile and accurate tool for bearing capacity predictions. Unlike the original depth factors unique to each method, which may not fully address complex soil and footing conditions, the unified depth factor is developed to enhance prediction accuracy for a wide range of conditions, including both flexible and rigid footings under varying flow rules (ψ = 0 and ψ = φ). This depth factor corrects for modeling errors, emphasizing the importance of pairing the correct set of N-factors with their corresponding depth factor. By offering a singular depth factor that aligns with the outcomes of finite element analysis, this paper not only simplifies the computational process but also enhances the accuracy of bearing capacity predictions across a diverse range of soil conditions and footing types. The comparative analysis, based on finite element analysis, validates the proposed method's effectiveness, showcasing its potential to significantly refine foundation design practices by comparing it with both traditional and newly developed depth factors. [ABSTRACT FROM AUTHOR]

Precise bearing capacity prediction of circular foundations is essential in civil engineering design and construction. The bearing capacity is affected by factors such as depth, density of soil, internal angle of friction, cohesion of soil, and foundation radius. In this paper, an innovative perspective on a fuzzy inference system (FIS) was proposed to predict bearing capacity. The uncertainty of fuzzy rules is eliminated by using Z-number theory. The effective parameters, i.e., depth, density of soil, internal angle of friction, cohesion of soil, and foundation radius were considered as inputs to the proposed model. To compare regression and FIS model with Z-based FIS, statistical indices such as the coefficient of determination (R2), root mean square error (RMSE), and variance account for (VAF) were employed. For training and testing Z-FIS, the R2 was (0.977 and 0.971), the RMSE was (1.645 and 1.745), and the VAF was (98.549% and 98.138), whereas for the FIS method, the values were (0.912 and 0.904), (5.962 and 6.76), and (90.12% and 88.49%). It should be mentioned that Z theory decreased the computational time by 89.28% (174.04 s to 18.65 s). The comparison of the statistical indicators of the presented models revealed the superiority of the Z-FIS model over the FIS. Notably, sensitivity analysis revealed that the most effective parameters on bearing capacity are internal angle of friction, depth, and soil density. [ABSTRACT FROM AUTHOR]

Soil spatial variability is a common situation in marine geotechnical engineering, while most studies have primarily focused on evaluating the uniaxial vertical (V), horizontal (H), or moment (M) bearing capacity of foundations in spatially variable clay. Whereas the process of combined bearing capacity analysis by probe method is complex, resulting in low efficiency. As a result, the simplified modified swipe (SMS) method is proposed in this paper, which can represent the capacity in any direction of the load space accurately and takes just 6.5 times the duration of a single probe loading for a half-failure envelope. Based on the established three-dimensional random finite element models, the effectiveness of this method is demonstrated by analyzing the combined bearing capacity of five kinds of foundations in spatially variable clay. Furthermore, Monte Carlo simulations revealed that the spatial variability of the soil cause various failure envelopes, and the response of the combined bearing capacity is not identical in all directions. The VHM failure envelopes with different probabilities are given and could be found that the safety factors recommended by the guidelines are insufficiently conservative for structures susceptible to soil spatial variability. Finally, a strategy for applying different safety factors to both load directions is proposed, which could be helpful for the design of foundations in spatially variable clay. [ABSTRACT FROM AUTHOR]

Shallow foundations are usually built above the groundwater table. In such cases, this soil is considered dry in analysis and design, while it is actually an unsaturated soil. This unsaturated soil can lead to many geotechnical issues, such as swelling when wet and collapsing when dry. It can also change the soil's shear strength, which in turn affects the bearing capacity of the soil. The classical principles of saturated soil are often not suitable for explaining these phenomena. Limited studies dealt with a large scale model close to the field conditions for such soil and therefore, there is much more room for improvement. The study reveals that compacting the expansive soil on the wet side of optimum is capable of reducing swelling pressure and the expansion index for both the bentonite–sand mixture and kaolin soil. The bearing capacity of a footing resting on both swelling and non-swelling soils decreases noticeably with the increase in the soil degree of saturation due to the effect of matric suction which increases the soil stiffness. The results show that the measured bearing capacity is (1.1–3.3) higher than that estimated by Terzaghi equations. [ABSTRACT FROM AUTHOR]

It is reported in the literature that the load-carrying capacity of the reinforced sand bed increases with increasing the footing settlement. However, the nature of settlement plays a critical role in shallow foundation designs due to the conditional allowable settlement of the footings. In this present study, laboratory model tests have been performed on a model jute geotextile reinforced sand bed under 1g condition. The associated scaling laws are adopted for the geometrical parameters of the model footing and reinforcements as proposed in the literature. On the other hand, a new approach has been developed for the model reinforcements for scaling down of geosynthetic materials under 1g condition to simulate the condition of geosynthetic reinforcement layers as in the field or Ng conditions. The test results revealed that based on the scaling factors the model footing can be allowed to settle according to the criteria of footing settlement and allowable reinforcement tensile strains. Finally, the suitable guidelines have also been developed as per the safety considerations in order to understand the effect of reinforcement layers on the improvement of soil bearing capacity ratio (BCR) up to a certain settlement ratio (s/D) of the footing. [ABSTRACT FROM AUTHOR]

Current research has shown a nonlinear trend in the failure of soil, and the single tangent method is commonly adopted when coping with nonlinear problems of soil failure. However, the method equates a nonlinear criterion to an optimizable linear criterion, which may differ from the actual situation, resulting in conservative results. In this paper, two types of piece-wise log-spiral failure mechanisms for bearing capacity estimations, including symmetrical and unilateral mechanisms were proposed with the nonlinear Mohr-Coulomb criterion. The static bearing capacity of foundations was evaluated using the symmetric failure mechanism, while the seismic bearing capacity of foundations was evaluated adopting a modified pseudo-dynamic method based on the unilateral failure mechanism. The result shows that the bearing capacity calculated in the paper is smaller compared to the result using the linear Mohr-Coulomb criterion. For London clay, the static bearing capacity is reduced by about 45% at a foundation width equal to 1m. From the comparisons, it is found that the proposed approach of piece-wise log-spiral failure mechanism for bearing capacity estimation is effective. In addition, parametric studies show that the nonlinear parameters, the initial factor of seismic acceleration, the normalized frequency, and the damping ratio all have obvious effects on the seismic bearing capacity. A significant reduction in the seismic bearing capacity of the foundation occurs when the normalized frequency ωsH/Vs is equal to (0.5 + n)π (n = 0, 1, 2, ...). Considering that the approach proposed provides a strict upper bound to the bearing capacity, the result imparts confidence in the approach of analysis presented. [ABSTRACT FROM AUTHOR]

Most research studies on the behavior of footings on geocell-reinforced slopes were conducted using experimental model tests on small-scale slopes. Very few studies can be found in relation to 3D analyses using detailed geocell structures. It is, therefore, the aim of the present study to investigate this problem by using a 3D finite element analysis. The study begins with verifying the accuracy of the applied finite element method using the results of the experimental model tests on the unreinforced and geocell-reinforced footings on slopes. It continues with studying the effects of main design factors such as the slope angle (β), the depth of the geocell mattress (u), the soil internal friction angle (ϕ), and the footing setback (a) on the bearing capacity of the geocell-reinforced footings. Numerical results suggest that an increase in soil internal friction angle and a decrease in slope angle would both enhance the bearing capacity of unreinforced and reinforced footings. The geocell reinforcement proves to be more effective in improving the bearing capacity of steeper slopes with small friction angles. In addition, the optimum depth of the geocell placement was found to be 0.1 times the footing width (0.1B) regardless of the β and ϕ. Irrespective of the β, the optimum footing setback ratio (a/B) was obtained at 0.5. As a/B ˃ 2, the effect on bearing capacity vanishes. At a constant footing setback ratio (a/B < 2), the use of geocell reinforcement is more effective for steeper slopes. The findings in this numerical study are of practical significance to the geotechnical engineering community. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the bearing capacity of Drilling with a prestressed concrete (DPC) pipe pile under different end sealing and side grouting conditions. The High Strain Dynamic Testing (HSDT) was conducted to evaluate the bearing characteristics of full-scale DPC pipe piles. Moreover, base resistance theoretical formula considering end sealing effect and shaft resistance theoretical formula considering side grouting effect are presented. The theoretical results were compared with the recommended values of specification for traditional pipe piles and tested values to demonstrate the rationality of theoretical formulas and the superiority of end sealing and side grouting. Furthermore, the effects of sediment under the sealing concrete and grouting conditions on the bearing capacity of a single pile were discussed in detail to reveal the influencing mechanisms of end sealing and side grouting. The result showed that the presented base resistance theoretical formulas can estimate the effect of end sealing on the ultimate base resistance of DPC pipe piles with good accuracy. For 1 m pipe piles, end sealing increases the base resistance by up to 103.5% at most compared to unsealing pipe piles; total shaft resistance of piles with double or multi-pipe grouting is more than 37% higher than the recommended maximum value of traditional pipe piles in the pile foundation specification. In addition, the base resistance was significantly affected by the sediment thickness under the sealing concrete. The hole wall time-dependent deformation caused by drilling and unloading affected the side grouting significantly. [ABSTRACT FROM AUTHOR]

To investigate the flexural performance of Steel-FRP Composite Bars (SFCBs) reinforced Ultra-High Performance Concrete (UHPC) beams, eight concrete beams with different reinforcement ratio, types of concrete were designed and fabricated. Flexural performance tests were conducted to examine the effect of various parameters on bearing capacity, deflections, crack patterns, ductility, and failure modes. The results indicate a significant enhancement in the flexural capacity of tested beams with UHPC. The bearing capacity of SFCB–UHPC beam is higher than that of steel-reinforced UHPC beams, but less than that of FRP (Fiber-Reinforced Polymer) reinforced UHPC beams. The deformation and crack resistance ability of SFCB–UHPC beams fall between those of steel-reinforced UHPC beam and BFRP-reinforced UHPC beam. Increasing the concrete strength and SFCB reinforcement ratio can significantly enhance the deformation and crack resistance ability of SFCB–UHPC beam. All tested specimens exhibited ductile failure. At the serviceability limit state controlled by deflection/crack, the steel-reinforced UHPC beams and BFRP-reinforced UHPC beams exhibit the highest and lowest utilization factors of flexural capacity, respectively, and that of SFCB–UHPC beams falling in between. High-ductility UHPC enhances energy absorption, ductility, initial and secant stiffness. The reinforcement type has a minor impact on the energy dissipation of flexural beams. SFCB, on the other hand, enhances the ductility, initial and secant stiffness of specimens. Based on a simplified material constitutive model and fundamental assumptions, three failure modes for the SFCB–UHPC beam under bending were defined, along with their respective criteria. This enables the establishment of a simplified load capacity calculation formula. With reference to ACI440.1R-03, a stiffness calculation formula was developed to predict the deformation of SFCB–UHPC beams. This research can provide a technological reference for the design and analysis of SFCB-reinforced UHPC beams. [ABSTRACT FROM AUTHOR]

The finite element limit analysis solution presented in this paper offers novel approaches for estimating the ultimate bearing capacity of annular foundations on Hoek–Brown criterion. The study examines the effects of five of dimensionless parameters, including the ratio of internal to external radii, the depth ratio, the adhesive factor, the yield parameter, and the geological strength index, on the findings of bearing capacity as well as the processes of collapse. Furthermore, one of the soft-computing regression methodologies, the multi-objective evolutionary polynomial regression analysis (MOGA-EPR) method, is utilized along with the requirement of the FELA outcomes as input data. This paper provides accurate limit-state predictions for annular footings on diverse rock masses using the MOGA-EPR model. By using the MOGA-EPR approach, the findings are highly precise and trustworthy, empowering designers to choose the best annular foundation design for various Hoek–Brown material varieties. Moreover, this study extends its scope by encompassing the application of multiple linear regression, multiple nonlinear regression, and artificial neural network models for an extensive comparative analysis. The amalgamation of these models widens the evaluative framework, fostering a more comprehensive exploration of predictive capabilities and insights into the stability assessment of annular footings across rock mass conditions. Through this multifaceted approach, a holistic comprehension emerges, thereby enhancing the decision-making process pertaining to the design of annular foundations within diverse Hoek–Brown material contexts. [ABSTRACT FROM AUTHOR]

The reuse of scrap tires to save storage space and lower traditional disposal risks is an environmental challenge. Currently, recycled tires are considered low-cost, lightweight materials that can be used to improve soil, retaining walls, backfills and roadbeds. The present study investigated the effect of the tire-shred aspect ratio and weight percentage on the bearing capacity and displacement of a stabilized mechanical retaining wall with multi-plate anchors under static loading. To this end, sandy soil containing tire shreds with widths of 1 and 2 cm, aspect ratios of 1, 2, 3, 4 and 5 at 5%, 10%, 15% and 20% contents (weight percentage of soil) was examined. Direct shear tests were conducted to determine the shear strength parameters of the mixtures. It was found that an increase in the tire-shred content in the mixture at a fixed aspect ratio, the bearing capacity of the mixture increased. Also at a fixed aspect ratio, the horizontal wall displacement increased with an increase in the tire-shred content. The wall bearing capacity was determined to increase at a fixed tire-shred content with an increase in the aspect ratio of the tire shreds. The results of the particle image velocimetry showed that an increase in the tire-shred aspect ratio increased the strain on the particle slip surface. [ABSTRACT FROM AUTHOR]

Modem methods and technologies of surveying the berthing and shore-protection structures of the Balaklava Bay of the Republic of Crimea are addressed. [ABSTRACT FROM AUTHOR]

Beam-like members sustaining the combined action of transverse load and membrane force exhibit a special load response to progressive deflection. A theoretical model is therefore developed to depict the resistance behaviours of clamped reinforced concrete (RC) beams observed in tests. The support-induced membrane effects are simulated by a longitudinal spring and a rotational spring. The load responses to progressive deflection are obtained using the membrane approach, and the prediction accuracies of proposed method are validated by a series of four-point bending tests on hybrid fibre reinforced-lightweight aggregate concrete (HFR-LWC) beam. It is illustrated that the bearing capacities of clamped HFR-LWC beam are significantly enhanced by the membrane effect. Ultimate load of the clamped beam ranges from 64.0 to 184.0 kN, and the larger bearing capacity compared with simply supported beam is obtained. An ultimate load of 1.85 to 5.31 times the yield line value is achieved, and thereby, the ultimate resistance of the clamped beam might be seriously underestimated using yield line approach. A strong support constraint is beneficial for increasing the load-carrying capacity of clamped HFR-LWC beam, although the large longitudinal restraint stiffness would inevitably gives rise to brittle failure. The relative errors between predicted load and measured value are less than 7.23%, indicating that the presented model is a promising tool to estimate the ultimate load of clamped beam-like member. [ABSTRACT FROM AUTHOR]

The design process for pile foundations necessitates meticulous deliberation of the calculation pertaining to the bearing capacity of the piles. The primary objective of this work was to investigate the potential use of Coot bird optimization (CBO ) techniques in predicting the load-bearing capacity of concrete-driven piles. Despite the availability of several suggested models, the investigation of Coot bird optimization (CBO ) for estimating the pile-carrying capacity has been somewhat neglected in this research. This work presents and validates a unique approach that combines the Coot bird optimization (CBO ) model with the Multi-layered perceptron (MLP ) neural network and adaptive neuro-fuzzy inference system (ANFIS ). The findings of 472 different driven pile static load tests were put in a database. The proposed framework's building, validation, and testing stages were each accomplished utilizing the training set (70%), validation set (15%), and testing set (15%) of the dataset, respectively. According to the findings, MLP CBO and ANFIS CBO both offer remarkable possibilities for accurately predicting the pile-bearing capacity of a given structure. The R 2 values for ANFIS CBO during the training stage were 0.9874, while during the validating stage, they were 0.9785, and during the testing stage they were 0.987. After considering various kinds of performance studies and contrasting them with existing literature, it has been concluded that the ANFIS CBO model provides a more appropriate calculation of the bearing capacity of concrete-driven piles. [ABSTRACT FROM AUTHOR]

The paper presents the evolution of the bearing capacity of a pile model in calibration chamber after the application of a cyclic axial loading at a large number of cycles. This work is a part of the French research project ANR-SOLCYP which aims to understand the mechanisms governing the evolution of the bearing capacity of piles up to a very large number of cycles (105 cycles). The experimental study consists in using a calibration chamber in which axial cyclic loading is applied to pile model jacked into sand under a large number of cycles, up to 105, while measuring the axial shaft capacity before and after the cyclic sequence. Some key parameters have been investigated such as the cyclic displacement amplitude, the level of applied consolidation stress and the density index of the soil. It was found that after a large number of cycles of cyclic axial loading, the post-cyclic bearing capacity of the piles is significantly improved. Results analysis indicated that the mechanism of densification of the soil around the pile led to improve pile capacity. [ABSTRACT FROM AUTHOR]

In this article, the tensile failure mechanism and load-bearing capacity of the equal-thickness (ET) and variable-thickness (VT) L-shaped joint structures of CCF300/QY9511 materials in different transition regions were analyzed by numerical simulation and experiments. Based on the ABAQUS finite element simulation software, the improved Hashin criterion and the stiffness reduction method considering damage accumulation were used to write a user-defined subroutine, establishing a progressive damage model for carbon fiber composite materials. Numerical simulations were carried out to investigate structural failure and obtain the damage generation, evolution, and failure process of the L-shaped joint structure with bolt connections. The bearing capacity of the structure under two forms of equal-thickness transition and variable-thickness transition were studied in comparison; and the failure mechanism of the structure was determined by comparing with the experimental results. The study found that there were different failure mechanisms in the two joint structures: when the ET joint was loaded, the damage occurred first around the bolt hole, and then the damage expanded to the arcs until it completely failed; the initial failure of the VT joint occurred at the arcs, but when the load continued to increase to the peak load, the damage occurred near the bolt hole of the L-shaped frame, and the load dropped sharply. [ABSTRACT FROM AUTHOR]

Millions of tons of used glass are recovered worldwide each year. As an environmental friendly solution, the glass waste are collected and recycled to manufacture new glass products. Nevertheless, the additional cost associated with separating waste glass materials can be seen as an inconvenience in this closed loop recycling method. This is why it is very interesting to valorise this waste material in other areas. Using glass waste in geotechnical applications and road construction has showed a particular interest. However, using such technique is hampered by insufficient knowledge on geotechnical characteristics of mixtures of natural materials and glass waste. This research investigates using Recycled Glass (RG) to correct the grain size of an unbound granular material for road pavement. The reference material is a crushed limestone of a class 0–20 mm which presents a deficiency of fine aggregates. Bearing tests, mainly Proctor and CBR tests, were conducted on the reference material and the mixtures composed of natural material and RG. The hydraulic conductivity was also measured. The findings indicated that the addition of the fine part of glass waste allowed correcting the grain-size distribution and therefore the bearing capacity has been improved. Furthermore, the mixture of natural material and RG upgrades the permeability class, which contributes to the durability of pavement layers. [ABSTRACT FROM AUTHOR]

Although the thermomechanical behaviors of energy piles have been investigated through a limited number of full-scale tests with constant loads, the effect of multiple load levels on the bearing capacity of energy piles has not been fully implemented into these in situ tests in the past. We report six full-scale in situ tests on bored energy piles under heating or cooling conditions and multiple mechanical load levels in Shanghai, China. Each pile was tested with 24 h of mechanical loading, 48 h of heating or cooling, and 10 h of thermomechanical loading. We monitored the inlet and outlet water temperature, pile and soil temperature, pore water pressure in the soil, axial force of the pile, and pile head displacement, and analyzed the thermomechanical responses of the energy pile and the surrounding soil, as well as the bearing capacity of the energy pile. Our experimental results show that the mechanical responses induced by the temperature change in the pile were affected by mechanical load level. Larger mechanical load reduced the influence of temperature on the settlement of the pile top and on the variation of the axial force in the pile, and at the same time weakened the negative skin friction effect caused by heating and enhanced the positive skin friction effect caused by cooling. Furthermore, pore water pressure caused by changes in soil temperature decreased slightly, and excess pore water pressure increased with increasing mechanical load level and dissipated rapidly in low-permeability coefficient soil. Finally, we comprehensively discussed the vertical bearing capacity of the energy pile based on the thermomechanical responses of the pile and the surrounding soil. [ABSTRACT FROM AUTHOR]

Laboratory plate load tests are conducted on model footings resting on sand bed reinforced with plastic multi-directional reinforcements. The bearing capacity, settlement and heave are evaluated and the effect of depth to first layer, spacing between reinforcements in a layer, number of layers and spacing between layers are investigated. The bearing capacity at 25 mm settlement improved by almost 1.3 times for a single layer of reinforcement, placed at an optimum depth of 0.5B. An increase in number of layers beyond four resulted in a reduction in improvement of bearing capacity. Three layers of reinforcement, spaced vertically apart at 0.5B resulted in a maximum increase of 185% in the bearing capacity. For the same area, the multi-directional reinforcing elements provide additional confinement to the soil mass due to the three dimensional projections. Comparing the economic aspects, the multi-directional elements prove to be a viable alternative to the conventional planar geosynthetics. An artificial neural network based model has been developed in order to effectively predict the ultimate bearing capacity and settlements of the model footing, resting on reinforced sand. [ABSTRACT FROM AUTHOR]

Severe instability disasters of hard rock often occur in pressurized deep tunnels with support systems. To investigate the deformation characteristics, brittle fracture process, failure mechanism, and collaborative effect of the rock and support system in a pressurized deep tunnel, physical model tests were designed and performed. An analog material preparation method is proposed for simulating the brittle failure of deep tunnels. The test results indicated that the brittleness and the strength of the developed analog material were significantly increased compared to those of previously reported analog materials, and its characteristics were similar to those of deep hard rock. The physical model tests realistically simulated the instantaneous process of brittle fracture of a pressurized deep tunnel, and the mechanical response laws of deformation, digital images, and acoustic emissions were captured. The strains of the surrounding rock, the lining, and the bolt were the largest in the shallow part of the sidewall and gradually decreased away from the tunnel. The brittle cracking paths of the shallow rock were along the direction of the internal pressure, whereas that of the interior rock mass were along the direction of the maximum principal stress. The brittle failure of a pressurized deep tunnel is caused by the incompatible tensile strain of the surrounding rock under the control of the anisotropic stress field. The bearing capacities of the surrounding rock, the lining, and the bolt decreased successively. Cyclic loading and unloading of internal pressure can reduce the bearing capacities of deep tunnels, whereas a constant internal pressure has a supporting effect. Highlights: The brittleness and strength of the developed analogue material were significantly increased compared with those of previously reported analogue materials, and its characteristics were similar to those of deep hard rock. The processes of brittle fracture of a pressurized deep tunnel with support system were realistically simulated via physical model tests. The deformation characteristics, fracture mechanism, bearing ratio, and collaborative effect of the surrounding rock and support system in a pressurized deep tunnel were analyzed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Determining the bearing capacity of ring foundations on rock masses holds utmost importance within the framework of foundation design methodology. To examine the failure mechanism of ring foundations situated on Hock-Brown rock masses, the crucial bearing capacity factor (N σ) is analyzed. This analysis considered three dimensionless input parameters: the geological strength index (GSI), the yield parameter (mi), and the ratio of the internal and external radii (ri/ro). This study focuses on the development of a precise hybrid extreme learning machine (ELM) and least-square support vector machine (LSSVM) based on two swarm-based intelligence optimization algorithms, utilizing Harris hawks optimization (HHO) and particle swarm optimization (PSO). The primary objective of this study is to provide accurate predictions of the bearing capacity factor ( N σ ) for a ring foundation. Furthermore, the accuracy of the developed hybrid ELM-PSO, ELM-HHO, LSSVM-PSO, and LSSVM-HHO models was assessed through a comparison between the actual and predicted values of N σ using various performance metrics, uncertainty analysis, and rank analysis. The LSSVM-HHO and ELM-HHO outperformed the LSSVM-PSO and ELM-PSO models in predicting the N σ value. The proposed models can be used as soft computing tools to predict the N σ values in practical applications. [ABSTRACT FROM AUTHOR]

In the last few decades, there has been an increase in the popularity of helical piles in developed nations and their penetration in the construction field in developing countries. The multiple benefits of helical piles over conventional piles for smaller structures in densely populated or environmentally sensitive areas for both onshore and offshore construction have made it an obvious choice for many geotechnical engineers. Moreover, the development of high torque-generating machines has revolutionized the use of helical piles as their installation process has now become much easier and faster. Therefore, it is important to analyze the behavior of helical piles using modern and sophisticated techniques. Finite element method provides the flexibility of easy analysis of the working mechanism of helical piles by reducing cost, time, and effort and providing accurate results. Finite element analysis (FEA) incorporates more variables such as the stiffness properties, and soil-pile interactions and provides a load settlement curve, thus offering a more realistic result. In this paper, the characteristics and behavior of helical piles under different design parameters, loading directions, and soil conditions have been analyzed using finite element method in Plaxis 2D software. The parametric analysis demonstrates the influence of different design aspects and other conditions around the pile on its load-carrying capacity. The extent of influence zone formed around the pile upon loading and the deformation pattern at failure have been studied. The values of critical spacing ratio and critical embedment ratio have been determined for both cohesive and cohesionless soils. [ABSTRACT FROM AUTHOR]

Reinforcing soil beneath foundations is one of the standard methods to improve the foundation performance. However, soil relative density may affect the efficiency of reinforcement. This experimental study has been conducted on a model ring foundation resting on medium, dense, and very dense geogrid-reinforced sand. For this purpose, 17 tests were carried out to evaluate the effect of soil density and reinforcement depth and size on bearing capacity and settlement of the ring foundation and its normal contact pressure distribution. The results show that geogrid-reinforced sand with higher relative densities improves bearing capacity and decreases settlements significantly. It can be shown that implementing a geogrid layer that is equal to the dimensions of the footing is cost-effective. The scale effect analysis has been conducted for the model foundation, sand, and geogrid used in this research. Additionally, normal contact pressure distributions for unreinforced and reinforced sand are presented. Decreasing the depth of reinforcement transforms the form of normal contact pressure distribution from saddle to parabolic. [ABSTRACT FROM AUTHOR]

The issue skirted foundations, which are typically made of steel or concrete, feature a skirt beneath the periphery. These foundations are primarily used in offshore structures. They offer the advantage of reducing material costs and installation time. Unlike shallow foundations, skirted foundations transfer the load to a deeper level, thereby enhancing the foundation's bearing capacity and minimizing settlement. This study focuses on the performance of square-skirted foundations under static and seismic compressive loading by numerical and physical modeling methods. It specifically assesses the impact of skirt length on the bearing capacity and settlement of the foundation, considering a soil density of 40% under vertical load conditions. The analysis takes into account different skirt length-to-width ratios (L/B) of 0.0 (surface), 0.5, 1.0, and 1.5. The results indicate that the inclusion of skirts enhances the bearing capacity and settlement behavior of surface foundations on sand, with improvements increasing as skirt depth increases. These findings suggest that the implementation of skirts is an effective technique for reducing both displacements and acceleration in vertical directions, enhancing foundation resistance, and significantly improving the structure's response to earthquake loading. The experimental results align with numerical modeling, validating its use for large-scale designs. However, further investigations using full-scale tests are needed to generalize these results for real-world applications. [ABSTRACT FROM AUTHOR]

Helical anchor is a kind of novel foundation for floating offshore wind turbines, which should be subjected to combined tensile loading caused by wind, wave and current. However, the research about the capacity of helical anchor was mainly examined under uniaxial loading and scarcely explored under combined loading. In this study, three-dimensional finite element limit analysis is adopted to assess the bearing capacities of single-plate rigid helical anchors with different ratios of helix to shaft diameter, DH/DS and embedment ratios L/DS. Result shows that the vertical, horizontal and moment bearing capacities increase with increasing DH/DS and L/DS. The normalized V-H failure envelopes expands with increasing L/DS, while the normalized V–M failure envelopes tend to contract with the increase of DH/DS. With increasing DH/DS or decreasing L/DS, the normalized H-M failure envelopes expand when the horizontal and moment loading act in the same direction and contract when they act in the opposite direction. The effect of DH/DS and L/DS on the shape of H–M failure envelope become insignificant when L/DS ≽ 4. A series of failure mechanisms under different loading conditions were observed and can be used to explain the trend. Besides, a series of approximate expressions were proposed to fit the uniaxial bearing capacities and the failure envelopes. [ABSTRACT FROM AUTHOR]

In recent years, robots with leg mechanisms have received considerable attention as high-running planetary exploration rovers. Rovers undertaking planetary exploration require outstanding running performance to travel on loose ground on which they mostly slip and hardly move forward. The movement of the rover easily deforms the surface of loose ground. This problem can be solved by increasing the bearing capacity. The bearing capacity, the resistance force exerted on the rover legs when they make contact with the ground, needs to be sufficiently large to prevent legged rovers from slipping on loose ground. The bearing capacity can be increased by compaction of the ground by imparting vibrations. This study investigates the relationship between the bearing capacity in the horizontal direction and vibration parameters because this relationship offers valuable information for improving the running performance of legged rovers. First, we investigated the effect of changing the vibration parameters on the bearing capacity. Our experimental results show that the bearing capacity is related to vibration acceleration. These results suggest that the bearing capacity can be estimated from the vibration acceleration. Next, the frequency and amplitude were compared as vibration parameters to devise an efficient method for increasing the bearing capacity. The results of these experiments showed that high-amplitude vibrations increase the bearing capacity to a greater extent than high-frequency vibrations. The reason is that high-amplitude vibrations generate larger additional vibrations by the collision between the rod and the ground than high-frequency vibrations. This knowledge is valuable for selecting a suitable vibration that can efficiently increase the bearing capacity. This study suggests a method of facilitating further planetary exploration using legged rovers. [ABSTRACT FROM AUTHOR]

Bearing capacity of reinforced footing clearly depends on the characteristics of interface between geosynthetic and soil. A suitable solution for increasing the bearing capacity is to treat the geotextile surface by various additives. This study reported the results of plate load test on square model footing resting on reinforced sand with and without treated geotextiles to survey the effects of the treatment of geotextile on settlement and bearing capacity. The treated geotextiles were made using additives onto the surface, with a layer of sand located on the top. Geotextile sides were treated in the same way. Different additives including the lime, cement, emulsion, and the effect of the number of layers were considered. The bearing capacity ratio values (BCR), improvement ratio values (IR) and variation of load-settlement ratio obtained from the treated models were presented. The results showed that the treatment of geotextile has a great effect on the behavior of reinforced sand and thus bearing capacity. Also, the test results indicated that lime-treated geotextiles provided better improvement than other additives. The maximum improvement in the bearing capacity of square footing supported on treated geotextiles was found to be 75% compared with the pristine geotextiles. [ABSTRACT FROM AUTHOR]

The foundation of a lunar habitation may be either smooth or rough with different shapes in the light that various concepts of the lunar base have been proposed, which require a good understanding of the bearing behavior of the lunar soil under plates with different shapes and roughness. Therefore, the three-dimensional distinct element method (3D DEM) is employed here to perform plate load tests on lunar soil simulant using the force-driven method. The soil failure mechanism under different plates is first described at various scales with detailed DEM studies of the load-settlement curve, stress path, ground heave, void ratio changes, and normalized-velocity field. Following these, the shape factor and coefficient of plate roughness are discussed by comparing the DEM and theoretical results. The results show that a typical general failure model can be identified for the strip plate, a local failure model for the circular and square plates, and a Hill model for the smooth plate from the ground heave, void ratio changes, and normalized velocity field. The shape factors for bearing capacity determined by the settlement criterion are close to those by the Terzaghi method with an error of nearly 10%, and the shape factors for the deformation modulus are similar to those in Chinese standard with an error of nearly 20%. In addition, the coefficient of plate roughness for the semi-rough plate is close to those predicted by the Meyerhof and Kumar methods with an error of nearly 5%. [ABSTRACT FROM AUTHOR]

In recent years, constructing natural aggregates as a base layer for the roads has increased. Natural resources will run out as long as human consumption of them continues. Recycled concrete aggregate (RC) has thus emerged as a substitute material for the building of road base layers. Additionally, RC can be utilized to create interior city highways. The base layer for roads must have sufficient strength to support the working load on the pavement surface without damage deforming. As a result, the focus of this paper is on enhancing the structural performance of sandy soil reinforced with various RC percentages. The three key factors are relative soil density (Dr = 83 and 97%), recycled concrete aggregate reinforcing levels (RC = 0,5,10,15,20,25,30,40,50 and 100%), and reinforcement layer thickness (Rd = 0.0B, 0.5B, B, and 2B where B is the footing model width). Numerous laboratory experiments were conducted in order to examine the impact of important parameters on the properties of the mixtures. The plate bearing tests were carried out using a footing model (250 × 250 mm) inside a tank (1500 × 1500x1000 mm) to ascertain the stress–strain response, bearing capacity ratio (BCR), ultimate bearing capacity, and modulus of elasticity of the tested mixtures. It is clear that raising the RC has no effect on the diameters of the grains. It was found that as RC increased, the mixture's bulk density increased but specific gravity decreased. Maximum dry density rose as RC rose, whereas water content fell. It was noted that BCR unquestionably increased as RC increased for all RC levels and all values of settlement ratios. The appropriate reinforcing layer thickness is suggested to be no more than 2B. As the RC concentration in the sand and Rd increased, the difference between two pressure-settlement curves of densities 83% and 97% significantly decreased. Furthermore, when RC reaches 50%, two curves are roughly comparable. At RC = 50%, it is advised that the relative density of 83% is sufficient to produce the same behavior as the relative density of 97%. It was found that as RC and Rd grew, the tested mixtures' ultimate bearing capacity and elasticity modulus increased as well. A novel proposed formulas are developed to compute bearing capacity ratio, ultimate bearing capacity, and elasticity modulus of the tested mixtures taking into account the influence of RC, reinforcement layer depth, settlement ratio, and the relative density, and its results agree with the experimental results. [ABSTRACT FROM AUTHOR]

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In this paper, the performance of ladle furnace slag (LFS), a by-product of secondary steel refining, is evaluated as a binder to stabilize clayey soils of low bearing capacity. The aim is to define whether additions of this by-product to clayey soil can stabilize the soil in accordance with the technical specifications of Spanish standards. To do so, three different soils stabilized with 5% LFS were compared with the same soils stabilized with 2% lime and with no stabilization, in order to investigate their different behaviors. The chemical and mineralogical characterizations of all the soil mixes were conducted using X-ray fluorescence, X-ray diffraction, and scanning electron microscopy. The Atterberg limit test was used to study the plastic behavior of the soils, and the results of compaction, bearing capacity, unconfined compressive strength, and direct shear strength (cohesion and friction angle) tests defined their strength characteristics. The analysis was completed with the pH monitoring of the mixes along the curing time in order to relate the pH changes with the strength evolution. The addition of LFS to the soils has resulted in an increase in the liquid limit and plastic limit, causing therefore a slight decrease in the plasticity index. All the soils showed increases between 30% and 70% in their California Bearing Ratios immediately after mixing with 5% LFS, and after 90 days of curing, improvements of 30–188% in their unconfined compressive strength were noted in comparison with untreated soil, which were higher than the lime-stabilized soils. The cohesion of soils stabilized with LFS at 28 days of curing obtained improvements ranging from 40 to 300% depending on the type of soil. However, the friction angle showed a slight increase of 10% in two of the soils and zero in another. The high initial pH in LFS-stabilized soils was maintained during the curing time, which favored the development of pozzolanic reactions that improve the soil strength. These results confirmed that the substitution of lime with LFS is a feasible option for soil stabilization. [ABSTRACT FROM AUTHOR]

For stability control of gob-side entry (GSE) in a deep mine, surrounding rock reinforcement and roof cutting are commonly used technical methods. However, there is still a lack of scientific quantitative design guidelines for the above two methods. In this paper, taking the bearing capacity of the surrounding rock as the starting point, a mechanical model of a GSE surrounding rock structure in a deep mine is established, and a mathematical expression for the load-bearing capacity of the yield pillar and the longwall panel rib are obtained. Taking the ultimate bearing capacity of the yield pillar and longwall panel rib as metrics, the state of GSE surrounding rock is divided into four categories according to the relationship between the actual bearing load and the ultimate bearing capacity of the yield pillar and longwall panel rib. For each condition, corresponding manual control and quantitative design methods are proposed, and the control method is preliminarily applied through field engineering examples. This study can provide theoretical and technical support for the stability control of a GSE in a deep mine. [ABSTRACT FROM AUTHOR]

This study presents the results of a comprehensive numerical modelling that was conducted to investigate the effect of different variables and parameters on the ultimate bearing capacity, qu, of strip footing on a sand layer underlying a clay deposit soil layer with a localized weak zone. The numerical model was developed using the finite difference FLAC2D software. The parameters investigated in this study are the thickness of the top sand layer, the undrained shear stress ratio of clay soil, and the location, depth, width, and height of the weak zone. The results clearly showed that the ultimate bearing capacity of strip footing, qu, decreases due to the presence of a weak zone, with the degree of reduction is a function of the soil properties and the weak zone parameters (depth, location and geometry), the value of qu increases with increasing the normalized thickness of the top sand layer, H/B, and with increasing the normalized vertical and horizontal distances of the weak zone (Yw/B, Xw/B). However, the qu value decreases significantly with increasing the normalized width and height of the weak zone (Bw/B, Hw/B) up to certain limits, where the reduction is negligible. However, the value of qu significantly increases with the increase in the shear strength of the clay layer, which indicates that higher shear strength of soil reduces the effect of the weak zone on qu, and therefore the weak zone has a different effect on different soil type and different soil strengths. [ABSTRACT FROM AUTHOR]

This study presents an analysis of the influence of geogrid distribution on the bearing capacity of granular soils. For this purpose, the bearing capacity is compared based on 3 arrangements, uniform, trapezoidal, and inverted trapezoidal, with 2 types of geogrids, biaxial and multiaxial, under the application of an axial load. The tests performed were analyzed in three forms in which the trapezoidal distribution was the best arrangement for biaxial and multiaxial geogrids. The first analysis considers the peaks for each stress–strain curve, the trapezoidal distribution increases the bearing capacity by 36% and 33% for biaxial and multiaxial geogrids, respectively. The second analysis considers a settlement ratio (s/B) of 10%, which had an average increment of 30.5% for the two types of geogrids. The third analysis considers a 20% of s/B ratio, which showed a 56% and 81% of bearing capacity ratio (BCR) increase for biaxial and multiaxial geogrids respectively. From an economical and environmental analysis, the trapezoidal distribution saves 7% of material compared to the traditional uniform distribution. The comparison between physical and numerical models with theoretical equations is presented.Article highlights: The bearing capacity of soil determined through numerical, physical, and theoretical models increases with the use of different types and arrangements of geogrids. The results of the theoretical equations applied to the physical models indicate that for a trapezoidal arrangement with biaxial geogrid, the equation of Sharma (2009) presents a better approximation, underestimating the bearing capacity by 7%, while the equation of Binquet and Lee (1975) overestimates the capacity by 13%. The numerical model underestimates the bearing capacity by 14% compared to the physical model, indicating that the use of the theoretical equation of Sharma (2009) is more appropriate for trapezoidal geogrid arrangements. The comparison of BCR increment considering an s/B ratio equal to 10% and 20% shows that the equation of Sharma (2009) presents a better approximation for an s/B ratio equal to 10% for all cases. Meanwhile, the equation of Binquet and Lee (1975) presents an adequate approximation for s/B equal to 20% for biaxial geogrids. [ABSTRACT FROM AUTHOR]