Strip Footings Research Articles

Theoretical and Numerical Studies on Strip Footing Resting on Encapsulated Soil Mass

Theoretical and Numerical Studies on Strip Footing Resting on Encapsulated Soil Mass

Seismic Bearing Capacity of Strip Footing on Excavations Considering Soil Strength Anisotropy Using Modified Pseudo‐Dynamic and Pseudo‐Static Approaches

ABSTRACTAlthough considerable research has explored the static and seismic bearing capacity of strip footings on slopes or excavations, the influence of clay strength anisotropy on the bearing capacity of strip footing near excavations, specifically considering pseudo‐dynamic conditions, remains unexplored. This study used the finite element limit analysis (FELA) method to evaluate the impact of clay strength anisotropy on the seismic bearing capacity of strip footings. The effects of various dimensionless parameters on the bearing capacity were examined, which include shear wavelength, the setback distance ratio, vertical height ratio, soil strength ratio, soil strength heterogeneity, anisotropic ratio, and horizontal and vertical acceleration coefficients. Design charts were developed to compute the seismic bearing capacity of strip footings on nonhomogeneous and anisotropic excavations under pseudo‐static conditions. Furthermore, the effects of vertical acceleration coefficients and shear wavelength on the seismic bearing capacity of strip footing near excavation in nonhomogeneous and anisotropic soils were investigated.

Drained Bearing Capacity of Strip Footings on Two-Layered Sand Soil Slope

Drained Bearing Capacity of Strip Footings on Two-Layered Sand Soil Slope

Effects of inclined loads on strip footings with an underlying tunnel

The self-developed Finite Element Limit Analysis (FELA) code was utilized to examine the ultimate bearing capacity of strip footings positioned above tunnels affected by inclined loads. Bearing capacity factors were predicted using both upper bound (UB) and lower bound (LB) solutions, with a variance of less than 3 %. The primary focus of this study lies in assessing the influences of underlying tunnels and inclined loads on potential failure modes. In particular, the concept of failure envelopes was introduced, by which the load properties (inclination angle), the tunnel location (relative lateral distance and longitudinal distance from the footing) and the material properties of rock masses (GSI, mi, sci, g) were involved in to facilitate preliminary designs. In addition to envelopes, the transition among failure patterns was summarized, resting with any possible factors.

Kinematic bearing capacity analysis of strip footings on reinforced soils using discretisation technique

The kinematic discretisation technique of upper bound limit analysis is adopted in this study to evaluate the limit load of a strip footing located on the soils reinforced with different geosynthetic layers. The reinforcement is assumed to withstand the tension but not bending moment. The failure model of the reinforced foundation soil is generated using the discretisation method, a ‘point by point’ technique. Two failure modes of the reinforcement, the tensile rupture and sliding, are considered in the analysis. This article proposed the formulas for the first time to evaluate the effect of soil friction angle φ on the ultimate bearing capacity and on the failure mechanism of foundation. The calculation results are given considering different reinforcement layers, which describe the impact of different reinforcement depth and length on the ultimate bearing capacity. The optimum positions of different reinforcement layers and the optimum reinforcement length are obtained. The bearing capacity ratios are also presented in figures combing impact of reinforcement depths, soil cohesion and friction angle. The present method was verified by the results reported in literature. The present method can provide a reference for the footing design on the reinforced soils.

Experimental Investigation of Strip Footings on Weak Clay with a Granular Trench

Experimental Investigation of Strip Footings on Weak Clay with a Granular Trench

Hybrid artificial neural network models for bearing capacity evaluation of a strip footing on sand based on Bolton failure criterion

This paper employs the Bolton failure criterion, incorporating strength-dilatancy relationships, to analyze the bearing capacity factor of a strip footing on dense sand. Utilizing finite element limit analysis (FELA) based on the lower and upper bound theorems, the study presents the results as average bound solutions. By using the Bolton model, the b parameter is first calibrated and found that it should be about 3.50 to align the ultimate bearing capacity (qu) from FELA to have a good agreement with that from experimental test results from previous studies. The influence of parameters relevant to the Bolton failure criterion is analysed, showing that an increase in relative density (DR) significantly affects the variation in the bearing capacity factor (Nγ) at higher Q values, while lower Q values inhibit dilatancy due to soil crushing. The width of the strip footing (B) has a decreasing effect on Nγ at higher Q values, and the unit weight (γ) changes minimally impact Nγ within the range of 16–22 kN/m3. Additionally, an increase in the critical state friction angle (ϕcv) consistently increases Nγ, highlighting its direct correlation with soil shear strength. A hybrid artificial neural network (ANN) model integrates machine learning with four optimization algorithms: Imperialist Competitive Algorithm (ICA), Ant Lion Optimization (ALO), Teaching Learning Based Optimization (TLBO), and New Self-Organizing Hierarchical Particle Swarm Optimizer with Jumping Time-Varying Acceleration Coefficients (NHPSO-JTVAC). Comparative rank analysis of hybrid ANN models based on the selection of the optimal number of hidden neurons demonstrates that the ANN-TLBO model excels in predicting the bearing capacity factor, achieving a score of 48. This conclusion is corroborated by an error heatmap matrix, which indicates a minimized percentage of error relative to other hybrid ANN models. Importance analysis identifies particle crushing strength (Q) as the most significant factor influencing the bearing capacity factor (Nγ).

Parameters affecting performance of fully instrumented model testing of strip footings on geocell-reinforced soils

A thorough study was conducted to assess the performance of the strip footing reinforced with geocells in sand, focusing on understanding the enhancement effects and geocell reinforcement mechanisms. Critical factors such as geocell modulus, height, soil relative density and load eccentricity were examined through fully instrumented model tests. Measurements included surface displacement profiles, strains on the geocell layer, subsurface pressure distribution and other relevant parameters. Results revealed that the strip footing on geocell-reinforced sand beds exhibited better performance compared to those on unreinforced soil, characterized by increased load-carrying capacity and reduced settlements. Notably, stiffer geocells improved performance significantly, with a 40% higher modulus enhancing the bearing pressure by up to 25%, due to better confinement and anchorage effects. Conversely, geocells with a lower modulus demonstrated more effective vertical stress distribution. Furthermore, increased geocell height moderately enhanced footing performance by improving confinement, although wall buckling under eccentric loading limited major gains. Dense soils under centric loading exhibited up to a 20% better improvement in bearing pressure than loose soils due to higher strain mobilization within the geocell layer. These findings highlight the crucial role of geocell and soil properties, as well as loading conditions, in optimizing reinforcement effects for strip footings.

Erratum to: Application of MGGP in Predicting Bearing Capacity of a Strip Footing Resting on the Crest of a Marginal Soil Hillslope

Erratum to: Application of MGGP in Predicting Bearing Capacity of a Strip Footing Resting on the Crest of a Marginal Soil Hillslope

Experimental study on the performance of geogrid-reinforced soil (GRS) walls under monotonic footing loading

Geogrid-reinforced soil (GRS) is a widely employed compound material in the construction of retaining walls. This paper presents a set of reduced-scale model tests to study the performance of GRS walls with dry backfill under monotonic footing loading, varying parameters such as wall inclination angle and the number of reinforcement layers. Lateral deflections of the retaining wall, bearing capacity of the footing and the failure mode of the soil were analysed. The results indicated that augmenting the reinforcement layers will lessen wall lateral deflections, and increasing the angle of inclination could significantly enhance ultimate bearing capacity of the footing. A linear relationship was found between the overall lateral deflections of the retaining wall and the footing settlement. The failure of geogrid could lead to a breakdown in the connection between the geogrid and the soil, consequently causing local failure. The failure modes of the GRS wall under strip footing was composed of shear failure in the reinforcement layer and spiral failure in the weak layer. At last, the logarithmic spiral analysis method was modified slightly to calculate the ultimate bearing capacity. The analytical solution and the outcomes derived from experimental models exhibit a high level of concordance.

Closure to “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Closure to “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

A Coupled Effect of Eccentric Loading and Upward Seepage on Collapse Settlement of Strip Footings on Reinforced Sand

A Coupled Effect of Eccentric Loading and Upward Seepage on Collapse Settlement of Strip Footings on Reinforced Sand

Discussion of “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Discussion of “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Behaviour of sheet pile wall on sloping ground for strip footing as surcharge with coir geotextile reinforced backfill soil

Behaviour of sheet pile wall on sloping ground for strip footing as surcharge with coir geotextile reinforced backfill soil

Reliability Assessment of Strip Footings on Spatially Varying Sand

Reliability Assessment of Strip Footings on Spatially Varying Sand

An Experimental and Numerical Investigation of Strip Footing Behavior on Geogrid-Reinforced Embankment Resting on Soft Soil

An Experimental and Numerical Investigation of Strip Footing Behavior on Geogrid-Reinforced Embankment Resting on Soft Soil

Ultimate Bearing Capacity of Weak Foundations under Coal Pillars

In many underground coal mines, a seam is underlain by weak floor material, and the load-carrying capacity of a pillar may be limited not by its own strength but by the bearing capacity of the floor. It has been proposed that bearing capacity may be estimated by formulae such as those of Terzaghi for structural footings on soil, but that approach is generally not valid because, for the slip surfaces assumed in the derivations of the formulae, the rock rises out of the floor beneath adjacent pillars. In the limiting equilibrium analysis proposed here, the distance to the side of a pillar to which a slip surface extends can be constrained according to the roadway or bord width. Examples are shown of the computation of bearing capacities of both homogeneous and multilayer dry and fully saturated floors, and results compared with those of elastoplastic finite element analysis. An approximate comparison with bearing capacities according to Terzaghi's formula for a strip footing is also presented for the hypothetical cases of wider roadways for which the assumed slip surfaces do not extend under adjacent pillars. For the cases considered, there is satisfactory agreement with Terzaghi’s analysis and good agreement with the results of finite element analysis. However, only one finite element analysis was carried out, and it remains to be seen whether such agreement is consistently achieved for ranges of floor strength parameters and horizontal stress.

The Effect of Oil Contaminated on Collapse Pattern in Gypseous Soil Using Particle Image Velocimetry and Simulation

Gypseous soil covers approximately 30% of Iraqi lands and is widely used in geotechnical and construction engineering as it is. The demand for residential complexes has increased, so one of the significant challenges in studying gypsum soil due to its unique behavior is understanding its interaction with foundations, such as strip and square footing. This is because there is a lack of experiments that provide total displacement diagrams or failure envelopes, which are well-considered for non-problematic soil. The aim is to address a comprehensive understanding of the micromechanical properties of dry, saturated, and treated gypseous sandy soils and to analyze the interaction of strip base with this type of soil using particle image velocimetry (PIV) measurement and Plaxis 3D simulation. The results showed that high-resolution digital cameras captured soil deformation using PIV, displacement fields, and velocity vectors were generated, which helped identify different sand movement zones. Further, PIV showed punching and general shear failure in uncontaminated and soaked contaminated gypsum soils, respectively. Moreover, the Plaxis results corresponded well with the PIV, as material behavior models are essentially simplified representations of the actual behavior of footing and soil. Understanding soil deformation behavior is crucial for accurate engineering calculations and designs, making these findings valuable for geotechnical and construction engineering applications. Doi: 10.28991/CEJ-2024-010-07-016 Full Text: PDF

Estimation of ultimate bearing capacity of strip footings on cohesive-frictional soils using non-linear shear strength model

This study widely investigated the applicability of the ultimate bearing capacity formula from the Architectural Institute of Japan (AIJ) while considering the effect of footing width. An in-house RPFEM program was developed using a non-linear shear strength model that is sensitive to confining stress. The research focuses on evaluating how footing width and soil properties affect the ultimate bearing capacity of strip footings. Coefficients within the AIJ formula were calculated and compared to those derived from the RPFEM, considering different combinations of cohesive and frictional soil strengths across various footing widths. The RPFEM results closely matched those obtained from the AIJ formula. This suggests that using a non-linear shear strength model can accurately estimate the ultimate bearing capacity of strip footings on cohesive-frictional soils, taking into account the footing width.

Probabilistic Analysis of the Seismic Bearing Capacity of Strip Footings Using RAFELA and MARS

Probabilistic Analysis of the Seismic Bearing Capacity of Strip Footings Using RAFELA and MARS