Value Of Ultimate Bearing Capacity Research Articles

Tunnelling-induced nonlinear responses of continuous pipelines resting on tensionless Winkler foundation

Prevailing analytical approaches for tunnelling-induced soil-pipeline interactions predominantly rely on linear analyses, limiting their applicability in nonlinear scenarios. This study introduces a novel tensionless Winkler solution that accounts for gap formation and soil yielding, validated against three well-documented experiments and demonstrating superiority over existing Winkler solutions. Additionally, plate load tests refine traditional soil-bearing theories for buried pipelines in sand, providing subgrade stiffness and ultimate bearing capacity values pertinent to tunnelling-induced interactions. Parametric studies highlight amplified nonlinearity in pipeline behaviours with increased pipeline flexural rigidity and tunnel volume loss, due to soil-pipeline separation and subgrade yielding. Notably, ignoring gap formation and soil yielding leads to overly conservative estimations of pipeline deflections and bending moments. Higher subgrade moduli increase pipeline strains, while enhanced subgrade bearing capacity above the pipeline prevents soil yielding, rendering its effect negligible, whereas the bearing capacity beneath the pipeline is inconsequential in tunnelling scenarios.

Ultimate Bearing Capacity Calculation of Soil With Finite Element Method

Ultimate bearing capacity calculation is one of the most important factor to design foundations in geotechnical engineering. In this paper, ultimate bearing capacity values were calculated with finite element and analytical methods and compared. A case study of Bozozuk (1972) article is used for ultimate bearing capacity evaluations. On 30 September 1970, 600-ton weight concrete silo suddenly overturned and failure. After failure, in-situ Vane shear test and laboratory tests carried out to determine soil strength parameters for back analysis. In finite element analysis, Plaxis 2D was use. From analytical method maximum factor of safety FS= 1,09 from Terzaghi (1943) and minimum factor of safety FS= 0,97 from Meyerhof (1963). According to finite element analysis results, factor of safety was calculated as FS=0,64. All these results indicate that especially for complex and sensitive soil profiles, finite element analysis method may be used instead of analytical method.

ULTIMATE BEARING CAPACITY OF RING FOOTINGS ON SAND

The ultimate bearing capacity of ring footings for different conditions such as internal to external diameter ratio and angle of internal friction for sand is determined using the finite element program ELPLA Professional Edition, Version 9.0. A semi-empirical relation for determining the bearing capacity of ring footings that developed by other researchers is also described and used in compared. The value of ultimate bearing capacity is found to decrease significantly with an increase in (r =di/de), where di and de are the internal and external diameter of the ring, respectively. For larger values of internal friction angle of soil (), the magnitude of ultimate bearing capacity is seen to be higher than smaller values. The obtained results are compared with those available in the literature.

Experimental study on shear behavior of reinforced concrete deep beams with high-strength bars under uniform load

This study aimed to investigate the shear capacity performance for five deep beams with reinforced high strength concrete under uniform load to enable a better understanding of the effects of longitudinal reinforcement ratio and vertical stirrup ratio. The shear behavior test was completed by simulating uniform loading with eight points of concentrated loading. The dimension of five test specimens is 1600 mm × 200 mm × 600 mm. The longitudinal reinforcement ratio is set to 0.67%, 1.05%, 1.27%, and the vertical stirrup ratio is taken to be 0.25%, 0.33%, 0.5%. Through measuring the strain of steel bar, the strain of concrete, and the deflection of mid-span, the characteristics of the full process of shear capacity, the failure mode and the load–deflection deformation curve were examined. Based on this test, a 3D finite element model is established to verify the reliability of the test results. In addition, the calculation formula in the Code for Design of Concrete Structures (GB50010-2010) is used to calculate the shear behavior of deep beams, and the finite element calculation results and the code calculation results are compared with the test values. The results show that three typical failures mainly occur in deep concrete beams under uniform load: diagonal-compression failure, splitting failure, and local-compression failure. With the increase of longitudinal reinforcement ratio, the ultimate bearing capacity gradually increases. The increase of vertical stirrup ratio is helpful to improve the shear behavior of deep beams and inhibit the development of diagonal cracks. The 3D finite element model calculation results are close to the experimental values, and the finite element model can reasonably reflect the stress mechanism of deep beam members. Finally, the average value of ultimate bearing capacity of the experimental values compared with the code (GB50010-2010) calculation results is 2.208, and the results are on the conservative side. The obtained results show the code (GB50010-2010) has sufficient safety reserves.

A comparative study of bearing capacity of shallow footing under different loading conditions

ABSTRACT In the present study, the behaviour of a shallow rectangular foundation placed over the multiple layers of the geogrid reinforced sand under eccentric and oblique loads in both dimensions was studied. Various parameters were investigated in this study including the number of reinforced layers (N), eccentricity (e/B, e/L) and inclination of applied load (α). Bi-axial geogrid (Bx20/20)-reinforced sand and laboratory results were compared with PLAXIS 3D software keeping N, eccentricity ratios and angle of inclination as input parameters. The results present that the value of Ultimate Bearing Capacity (UBC) of model foundation found reduced as the axial eccentricity and inclination of applied loads increased. It also found that multiple geogrid-reinforced layers increased the UBC of about 75%. Finally, the model test results were analysed using PLAXIS 3D. A good agreement was originated between the laboratory results and numerical analysis.

Discussion on Calculation Formula of Standard Value of Ultimate Bearing Capacity of Single Anti-floating Pile in Technical Standard for Anti-floating of Building Engineering

Discussion on Calculation Formula of Standard Value of Ultimate Bearing Capacity of Single Anti-floating Pile in Technical Standard for Anti-floating of Building Engineering

Effect of aspect ratio of footing on behavior of two closely-spaced footings on geogrid-reinforced sand

This paper presents the results of laboratory model tests carried out on two closely-spaced interfering footings resting on the surface of geogrid-reinforced and unreinforced sand bed. The effect of aspect ratio (or shape) of the footing on interference behavior is studied by adopting three pairs of model footings of different sizes. The length (L) to width (B) ratio (i.e., aspect ratio) of the footings is varied from 1.0 to 2.0. The effects of single layer of geogrid on footing interference and bearing capacity improvement are investigated. The optimum depth of the geogrid layer for both interfering and isolated footings is found to be one-third of the footing width and it is not dependent on the aspect ratio of the footing. The optimum spacing between the interfering footings is found to be 1.5 times the width of the footing. Lower efficiency factor is observed for interfering footings resting on the reinforced sand compared to the unreinforced sand. Higher bearing capacity ratio (BCR) is observed for isolated footing than that of interfering footings when BCR is measured based on ultimate bearing capacity values of reinforced and unreinforced cases and BCR value increases as the aspect ratio of the footing increases.

Experimental and Numerical Study on the Influence of Corrosion Rate and Shear Span Ratio on Reinforced Concrete Beam

In order to study the influence of corrosion rate and shear span ratio on reinforced concrete beam, a numerical analysis method of corroded reinforced concrete beam was put forward. Bond‐slip relationship formula between reinforcement and concrete was suggested. A three‐dimensional finite element model of corroded reinforced concrete beam was established. Calculation method of ultimate bearing capacity for reinforced concrete beam was suggested. Ultimate bearing capacity experiment on 14 corroded reinforced concrete beams with different corrosion rates and shear span ratios was carried out. Numerical analysis results and experimental results were compared and analyzed. The results show that, for reinforced concrete beams with different corrosion rates and shear span ratios, load‐deflection curve can be divided into elasticity stage and plasticity stage. With the increase of corrosion rate and shear span ratio, ultimate bearing capacity of corroded reinforced concrete beam decreased. When shear span ratio was 3.0, if corrosion rate increased by 1%, experimental value of ultimate bearing capacity decreased by 1.002 kN. When shear span ratio was 2.4, if corrosion rate increased by 1%, experimental value of ultimate bearing capacity decreased by 1.849 kN. The numerical analysis method put forward in this paper was feasible, and the suggested ultimate bearing capacity calculation method for reinforced concrete beam has a high accuracy.

Evaluation of Foundation Beds Under Construction of New Road El Zagazig-Sinbillawain district, East Nile Delta- Egypt by Using Sedimentological and Geotechnical Studies.

The present paper is concerned with the study of sedimentological, mineralogical and geotechnical characteristics of the shallow facies and the foundation beds as well as their effects on the construction stability on a planned new road which will extend from El Zagazig to Sinbillawain district. It aims also to introduce some alternative solutions for the impact problems of these shallow facies. The present clay layer has an obvious dangerous effect on the constructions or any other establishments. Thirty one sediment samples from 31 boreholes have been collected at a depth from 0 to 20 m to investigate the sedimentology, physical, chemical and engineering properties. The results revealed that the initial water content ranges from 30.84 to 44.71%, the liquid Limit (LL) ranges from 51.33 to 71.36 %, the plastic Limit (PL) ranges from 20.5 to 36.85 %, the shrinkage limit ranges from 11.2 to 20.5 % and the plasticity Index (PI) ranges from 27.78 to 37.17 %. The x-ray diffraction analysis revealed that smectite (montmorillonite) and kaolinite minerals are the main components of the clayey sediments. The chemical tests of the studies samples revealed high concentration of sulfates that can increase the corrosion of the concrete foundations. Also the ultimate bearing capacity values are inferred.

Effect of aspect ratio of footings on settlement response of geosynthetic-reinforced granular fill-soft soil system

In this paper, a simple mathematical model is used to study the effect of aspect ratio of footings on settlement response of unreinforced or geosynthetic-reinforced granular fill-soft soil system. The length-to-width ratio (aspect ratio) of footings is varied from 1.0 (square) to 3.0 (rectangular). The foundation model is formulated for single layer of reinforcement. Parametric studies are carried out for a range of shear modulus values of granular fill and ultimate bearing capacity values of soft soil. It is observed that the aspect ratio has significant effect on settlement response and mobilised tension in geosynthetic layer. Both settlement and mobilised tension below the loaded area increase with an increase in the aspect ratio of footing for a particular loading intensity with constant width of the footing and constant soil parameters. The effectiveness of the reinforcement in terms of settlement reduction decreases due to increase of aspect ratio. The settlement decreases with an increase in ultimate bearing capacity of soft soil or shear modulus of granular fill. However, the rate of reduction of settlement with an increase in ultimate bearing capacity or shear modulus decreases as the aspect ratio increases.

Assessment of CPTU and static load test methods for predicting ultimate bearing capacity of pile

ABSTRACTFor the static pressure pile, the most important is to determine the standard value of ultimate bearing capacity of single pile. At present, the bearing capacity of pile foundation is usually determined by the cone penetration test (CPT) test. The empirical formula was used in practice, but the effect of excess pore water pressure generated in the penetration on the measured cone-tip resistance and side friction is neglected. In this study, based on the field test results at Fengyu playground at Yancheng Institute of Technology by CPT and CPTU methods, the bearing capacity of pile was predicted by the standardized methods, the LCPC (France method) and CPTU direct prediction methods. The prediction was also compared with the results by the static load test method. The prediction accuracy of the CPTU method was then discussed as well. The results reveal that the accuracy of the CPTU method was the highest, which was consistent with the results obtained by the static load test method. It is the best method and worthy of being applied for predicting bearing capacity of piles in engineering applications.

BEHAVIOR OF SQUARE FOOTING RESTING ON REINFORCED SAND SUBJECTED TO INCREMENTAL LOADING AND UNLOADING

The foundations of various structures are subjected to cyclic loading in addition to static loading in many situations. This paper presents the results of laboratory model tests on square footings supported on geogrid reinforced sand bed under incremental loading and unloading conditions for different densities of sand bed and U/B ratio. The incremental values of intensity of loads (loading, unloading and reloading) were applied on the footing to evaluate the response of a square footing and also to obtain the value of elastic rebound of the footing corresponding to each cycle of load. The effect of sand for the density 1.59 gm/cc, 1.69 gm/cc, and 1.79 gm/cc and for different U/B ratio of 0.2, 0.4, and 0.6were investigated on ultimate bearing capacity and the dynamic properties such as coefficient of elastic uniform compression Cu, coefficient of elastic uniform shear Cτ, coefficient of elastic non-uniform shear Cψ and the coefficient of elastic non uniform compression Cφ. The results shows that the value of ultimate bearing capacity and the value of Cu, Cτ, Cφ and Cψ of sand were increased by increasing the density of sand and with the increase of U/B ratio up to 0.4. The results of ultimate bearing capacity and values of dynamic properties (Cu, Cτ, Cφ and Cψ) for reinforced sand are greater than unreinforced sand bed.

Finite Element Analysis of Earthquake Resistance Behaviors of T-Shaped Concrete-Filled Rectangular Composite Steel Tubular Columns

By using finite element software ABAQUS, the nonlinear finite element analysis of earthquake resistance behavior of T-shaped concrete-filled rectangular composite steel tubular columns is carried out, furthermore, the analysis results and the corresponding experiment results are compared. The results indicate that the calculated value of ultimate bearing capacity is less than the experimental value, and the results of FEM analysis can match the experiment results better, and thus, it can better reflect the earthquake resistance behaviors of the specimens.

Research on Ultimate Bearing Capacity of Single-Layer Cylinder Latticed Shells Considering the Influence of <i>P-δ</i> Effect

The ultimate bearing capacity of the single-layer cylinder latticed shell structure, calculated without considering the single-member instability(P-δ effect), was not consistent to the actual value of ultimate bearing capacity in practice. The ultimate bearing capacity of the single-layer cylinder latticed shell structure was studied in detail by proposing a method of multi-element simulation, considering the member instability. The value of the ultimate bearing capacity decreased by 1.2% after considering the member instability taking a single-layer latticed shell structure with a 40m span as example. The analysis results show that the value of ultimate bearing capacity is tiny affected for the single-layer cylinder latticed shell structure with a small span and high rise-span ratio

Research on the Influence of the P-δ Effect to Ultimate Bearing Capacity of Single Layer Latticed Shell Structures

The ultimate bearing capacity of the single-layer latticed shell structure, calculated without considering the single-member instability(P-δ effect), was not consistent to the actual value of ultimate bearing capacity in practice. It was studied in detail that the ultimate bearing capacity of the single-layer latticed shell structure considering the member instability by proposing a method of multi-element simulation. The value of the ultimate bearing capacity decreased by 15.6% after considering the member instability taking a single-layer latticed shell structure with a 40m span as example. The analysis results show that the value of ultimate bearing capacity is significantly affected for the single-layer latticed shell structure with a small span and high rise-span ratio

Finite Element Analysis of Earthquake Resistance Behaviors in L-Shaped Concrete-Filled Rectangular Composite Steel Tubular Columns

By using finite element software ABAQUS, the nonlinear finite element analysis of earthquake resistance behavior of L-shaped concrete-filled rectangular composite steel tubular columns is carried out, furthermore, the analysis results and the corresponding experimental results are compared. The results indicate that the finite element calculated value of ultimate bearing capacity is less than experimental value; axial compression ratio of the specimen has little affect on its ultimate bearing capacity and earthquake resistance behaviors; the results of FEM analysis can match the experiment results better, and thus, it can better reflect the earthquake resistance behaviors of the specimens.

Comparative Bearing Capacity Analysis of Spread Footing Foundation on Fractured Granites

It is evident from several studies that ultimate bearing capacities calculated by traditional methods are conservative and subjective. For large civil structures founded on spread footings, cost-effective and safer foundation could be achieved by adopting optimum ultimate bearing capacity values that are based on an objective and pragmatic analysis. There is a pressing need to modify the existing methods for accurate estimation of the bearing capacities of rocks for spread footings. In practice, foundation bearing capacities of rock masses are often estimated using the presumptive values from Building Officials Code Administrators, National Building Code, and methods adopted by the American Association of State Highway and Transportation Officials. However, the estimated values are often not realistic, and site-specific analyses are essential. In this study, geotechnical reports and drill-log data from successful geotechnical design projects founded on a wide range of granites in eastern Tennessee were consulted. Different published methods were used to calculate ultimate bearing capacity of rock mass. These methods included Peck, Hansen and Thornburn, Hoek and Brown, Army Corps of Engineers, Naval Facilities Engineering Command, and Terzaghi's general bearing capacity equations. Wide variation was observed in the calculated ultimate bearing capacity values, which ranged over about two orders of magnitude. Only two of the methods provided realistic results when validated with plate-load test data from similar rocks.

Reply to the discussion by Das and Sivakugan on “Intelligent computing for modeling axial capacity of pile foundations”Appears in Canadian Geotechnical Journal, 47(8): 928–930.

The author welcomes and appreciates the interest and comments of the discussers, and the issues that they have raised are responded to as follows. The discussers recommend scaling the inputs and outputs data between [–1, 1] rather than [0, 1] because the transfer function used in the hidden layer was tanh, which is bounded by [–1, 1]. It should be noted that the sigmoid transfer function was used in the output layer and thus, the outputs must be scaled between [0, 1], commensurate with the limits of the sigmoid transfer function. Using the tanh transfer function in the output layer is not acceptable, as it does not comply with the underlying physical meaning of the bearing capacity problem. To explain this, consider the minimum value of ultimate bearing capacity of 290 kN and the maximum value of 4500 kN that was used in the driven piles model. If these two values are to be scaled between [–1, 1], the minimum ultimate bearing capacity will be equal to –1 and the maximum ultimate bearing capacity will be equal to 1. This means that, during artificial neural network (ANN) model training, the impact of the minimum ultimate bearing capacity will be as if it is exactly opposite to the impact of the maximum ultimate bearing capacity, which is not true from the physical point of view. In the hidden layer, however, the tanh transfer function was used, as it was found to

Ultimate Bearing Capacity Analysis of a Super-Long Rock-Socketed Filling Pile Based on Catastrophe Theory

Based on the catastrophe theory of nonlinear science, a cusp catastrophe model of a super-long pile under axially load is established, and the vertical ultimate bearing capacity expression of super-long pile is derived. By fitting pile load-settlement field test data, the coefficients of a hypothetical super-long pile load-deformation curve and the value of ultimate bearing capacity are obtained. The results show that: the cusp catastrophe model is applicable to the determination of ultimate bearing capacity, and can be used to predict the buckling failure of a super-long pile. In addition, a fold catastrophe model is established to investigate the effects of plastic softening on the ultimate bearing capacity. The derived ultimate bearing capacity expression implies that the radius of the elastic and the plastic softening zones are relevant to the ultimate bearing capacity.

Pressure settlement characteristics of rectangular footings on reinforced layered soil

A method has been proposed to obtain the pressure-settlement characteristics of square footings resting on reinforced layered sand based on constitutive laws of soils. The prerequisite of the method is the value of ultimate bearing capacity of reinforced layered soil. An approximate method has been proposed for the same. The value of settlement may be read directly from pressure-settlement curves for the given pressure intensity. Therefore, the rectangular footing resting on reinforced layered sand can be proportioned satisfying shear failure and settlement criteria.