scholarly journals A Method of Calculating the Bearing Capacity of Sand Pile Composite Foundations in a Mucky Soil Layer Considering Consolidation

2021 ◽  
Author(s):  
Peishuai Chen ◽  
Huiwu Luo ◽  
Dejie Li ◽  
Enlong Liu ◽  
Benliang Yang
Keyword(s):  
Bearing Capacity ◽  
Water Content ◽  
Effective Stress ◽  
Void Ratio ◽  
Soil Layer ◽  
Composite Foundation ◽  
Engineering Practice ◽  
Application Process ◽  
Sand Pile ◽  
Cavity Expansion Theory

Abstract In engineering practice, the measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value. Based on the sand pile construction and the load application process, a method of calculating the bearing capacity of the foundation based on the effective stress was proposed. Cavity diameter expansion in sand pile construction was simplified into a planar problem, and the cavity expansion theory was used to establish the expression of the rate of displacement and the horizontal stress increase. Based on the e–p curve and the calculation of the degree of consolidation, the relationships between the horizontal and vertical effective stress and the void ratio were obtained. According to the close relationship between the bearing capacity of the foundation in a mucky soil layer and the water content, an expression describing the relationships between the bearing capacity of the foundation, effective stress, void ratio, and water content was established. For the temporary engineering foundation treatment project, which needs a high bearing capacity but allows large foundation deformation, the design of sand pile composite foundations uses these relationships to take the consolidation effect of mucky soil into consideration, thereby reducing the replacement rate and lowering the construction cost.

scholarly journals A method of calculating the bearing capacity of sand pile composite foundations in a mucky soil layer considering consolidation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yongtao Zhang ◽  
Yuqing Liu ◽  
Huiwu Luo ◽  
Peishuai Chen ◽  
Dejie Li ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Water Content ◽  
Effective Stress ◽  
Void Ratio ◽  
Soil Layer ◽  
Composite Foundation ◽  
Engineering Practice ◽  
Application Process ◽  
Sand Pile ◽  
Cavity Expansion Theory

AbstractIn engineering practice, the measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value. Based on the sand pile construction and the load application process, a method of calculating the bearing capacity of the foundation based on the effective stress was proposed. Cavity diameter expansion in sand pile construction was simplified into a planar problem, and the cavity expansion theory was used to establish the expression of the rate of displacement and the horizontal stress increase. Based on the e–p curve and the calculation of the degree of consolidation, the relationships between the horizontal and vertical effective stress and the void ratio were obtained. According to the close relationship between the bearing capacity of the foundation in a mucky soil layer and the water content, an expression describing the relationships between the bearing capacity of the foundation, effective stress, void ratio, and water content was established. For the temporary engineering foundation treatment project, which needs a high bearing capacity but allows large foundation deformation, the design of sand pile composite foundations uses these relationships to take the consolidation effect of mucky soil into consideration, thereby reducing the replacement rate and lowering the construction cost.

scholarly journals Effect of soil moisture content on the bearing capacity of small bored piles in the unsaturated soil of Maringá, Paraná, Brazil

2021 ◽  
Vol 337 ◽  
pp. 03006
Author(s):  
Verônica Ricken Marques ◽  
Antonio Belincanta ◽  
Mary-Antonette Beroya-Eitner ◽  
Jorge Luis Almada Augusto ◽  
Ewerton Guelssi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Bearing Capacity ◽  
Water Content ◽  
Unsaturated Soil ◽  
Soil Layer ◽  
Matric Suction ◽  
Load Test ◽  
Degree Of Saturation ◽  
Static Load Test

In this study, the influence of soil moisture on the bearing capacity of piles founded in an unsaturated clay soil was investigated. The soil studied, composing the upper soil layer in Maringá, Brazil, is lateritic, has degree of saturation between 37% and 70% and has collapsible behaviour when wet. The bearing capacity was determined by full-scale load tests following the Brazilian Standard for Static Load Test. Two pile lengths, 4 m and 8 m, were considered. To analyse the influence of soil moisture, two tests were performed for each pile length: one in soil in its natural moisture content and another in pre-moistened soil. Results show that for both pile lengths, an increase in water content caused a significant reduction in bearing capacity, which is attributed to the decrease in the matric suction of the soil. This is confirmed by the results of the initial evaluation made on the variation of matric suction and its contribution to the bearing capacity with changes in water content. In summary, this study confirms that the pile bearing capacity in unsaturated soil is dependent on soil water content, highlighting the fact that the approach of assuming full saturation condition in the evaluation of the pile bearing capacity in such soil may give erroneous results. Moreover, this study demonstrate that the empirical methods most commonly used in Brazil for pile bearing capacity determination, the Décourt & Quaresma and Aoki & Velloso methods, are overly conservative when applied to the Maringá soil.

Assessing Relations Between Electrical and Geotechnical Properties of Sand-Clay Mixtures Using Jonscher Fractal Power Law Model

2019 ◽  
Vol 24 (1) ◽  
pp. 77-85
Author(s):  
Fred Kofi Boadu ◽  
Samuel Ampadu
Keyword(s):  
Water Content ◽  
Effective Stress ◽  
Power Law ◽  
Void Ratio ◽  
Geotechnical Properties ◽  
Dry Density ◽  
Power Law Model ◽  
Stress Levels ◽  
Intergranular Void Ratio ◽  
Intergranular Void

The geotechnical properties of unconsolidated geo-materials such as soils are influenced by modifications of their micro-structure, texture, mineralogy, water content and imposed effective stress levels. Fundamental relations between the characteristic electrical parameters describing the electrical responses soils based on a fractal power law model with scaling properties, and parameters influencing their geotechnical behavior are investigated. Low frequency electrical conductivity laboratory measurements were performed on sand and clay mixtures subjected to varying effective stress levels with concurrent measurements of their geotechnical properties. The conductivity spectra of the mixtures were described using a Jonscher fractal power law model characterized with three characteristic parameters, the dc conductivity ( σ dc ), the characteristic frequency ( f c ) and an exponent ( n). Changes in effective stress, water content, clay content, and other engineering properties of the mixture such as dry density, porosity, pore size and intergranular void ratio are discussed with respect to changes in the electrical parameters. The dc conductivity and characteristic frequency decrease with an increase in effective stress levels. The exponent, however, has the opposite behavior and increases with an increase in effective stress. As the water content increases, σ dc and f c increase while n decreases for all mixtures. With increasing stress levels, the average pore size of the mixtures decreases which results in a decrease in σ dc and f c but an increase in the values of the exponent. An increase in dry density of the mixtures leads to a decrease in σ dc and f c whilst n increases. Both σ dc and f c increase with increase in the intergranular void ratio of the mixture whilst the exponent values decrease with an increase in the intergranular void ratio. This study serves as a contribution to our quest in utilizing electrical geophysical methods, to assess and monitor non-invasively, the geotechnical properties of the subsurface in a less expensive and faster manner.

The Unified Solution of Gravel Pile Limit Bearing Capacity of Single Pile Composite Foundation

2013 ◽  
Vol 438-439 ◽  
pp. 1409-1413
Author(s):  
Qing Liu ◽  
Wei Ding ◽  
Ben Wang ◽  
Hong Hai Liu ◽  
Bing Yu Wang
Keyword(s):  
Bearing Capacity ◽  
Composite Foundation ◽  
Engineering Practice ◽  
Single Pile ◽  
Tube Model ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Double Shear ◽  
Tension And Compression ◽  
Gravel Pile

Based on the compaction effect of the gravel pile, the thick-walled tube model is established. Considering the gravel pile and pile materials with different properties of tension and compression of soil pile in the process of expansion, the influence of intermediate principal stress to improving the bearing capacity of foundation in the process of expansion, we use the planar axisymmetric double shear unified strength theory and present a gravel pile ultimate bearing capacity of single pile composite foundation unified expression. The theory study of gravel pile composite foundation and engineering practice has a certain guiding significance.

Strength of field compacted clays

1983 ◽  
Vol 20 (1) ◽  
pp. 36-46 ◽  
Author(s):  
Y. Liang ◽  
C. W. Lovell
Keyword(s):  
Water Content ◽  
Effective Stress ◽  
Void Ratio ◽  
Volumetric Strain ◽  
Test Series ◽  
Dry Density ◽  
Regression Equations ◽  
Strength Parameters ◽  
Long Term Conditions ◽  
Initial Void Ratio

The reported research established the relationships among the compaction variables (dry density, water content, roller type, and number of passes) and the shearing behavior of a residual clay (St. Croix) from sandstone and shale. Compacted material was tube sampled from test pads, and subjected to two test series: unconsolidated-undrained (UU), and saturated consolidated-undrained [Formula: see text] triaxials. Both test series were run at various confining pressures to approximate the end of construction and long-term conditions for several embankment depths.The UU tests showed an increase in strength with an increase in density or a decrease in water content. For the as-compacted samples, significant volume changes occurred during shear. The volumetric strain at failure decreased with increasing prestress effected by the roller.In the [Formula: see text]testing program, sample behavior after saturation under confinement was interpreted in terms of initial compacted conditions (and confinement). The effective stress strength parameters were functions of the compacted water content and void ratio. For a given initial void ratio, as the compaction water content increased, c′ increased and [Formula: see text] decreased. The volumetric strain upon saturation varied with the compacted water content, dry density, compactive energy, and the level of confinement. Skempton's A factor at undrained shear failure was dependent upon the initial void ratio and the degree to which the sample had been prestressed by the roller.Statistically valid regression equations for these dependent variables, viz., as-compacted strength, percent volume change due to saturation and consolidation, Skempton's A parameter at failure, and the effective stress strength parameters, were developed for field compacted St. Croix clay. Uses for such equations are given.

Lamellar Tearing Observations Regarding the Application of European Standards in the Field of Welded Steel Constructions

2018 ◽  
Vol 69 (6) ◽  
pp. 1352-1354
Author(s):  
Anamaria Feier ◽  
Oana Roxana Chivu
Keyword(s):  
Bearing Capacity ◽  
Brittle Failure ◽  
Engineering Practice ◽  
Steel Bridge ◽  
Railway Bridge ◽  
Welded Steel ◽  
Direct Replacement ◽  
Lamellar Tearing ◽  
European Standards ◽  
Comprehensive Study

The problem of corrosion for old steel bridges in operation is often solved by direct replacement of elements or structure. Only a few studies have been done to determine the efforts influenced by corrosion in those elements. In general, it is considered that a corroded element has exceeded the bearing capacity and should be replaced, but if the corroded element is secondary it could be treated and kept. A factor in the rehabilitation of an old steel bridge in operation is the aspect of structure. If the structure is corroded, rehabilitation decision is taken is easier. Lamellar tearing describes the cracking that occurs beneath the weld and can be characterized as a brittle failure of steel, in the direction perpendicular to the plane of rolling. The paper presents a comprehensive study on lamellar tearing and summarizes some conclusions about the prevention of them. The conclusions will be exemplified in the case of a railway bridge, with a main truss girder. The paper presents also some observations regarding the stress analysis in fillet welds, resulting from the engineering practice.

Impacts of Different Pile Parameters on Stress and Settlement of Composite Foundation

2011 ◽  
Vol 90-93 ◽  
pp. 387-392
Author(s):  
Ying Cui ◽  
Jun Hai Zhao ◽  
Shan Shan Sun
Keyword(s):  
Storage Tank ◽  
Yield Criterion ◽  
Composite Foundation ◽  
Engineering Practice ◽  
Foundation Design ◽  
Fem Model ◽  
Oil Storage ◽  
Oil Storage Tank ◽  
The Status ◽  
Important Significance

The composite foundation fully takes the carrying capacity of pile and soil into account, which decreases the settlement of oil storage tank foundation and differential settlement of oil storage tank bottom apparently. Analyzing the changes of stress and settlement under different conditions and optimizing the parameters of pile have important significance in engineering practice. In this paper, with an actual project of oil storage tank for background, basing on the Drucker-Prager yield criterion, the FEM model of composite foundation has been carried out by using ANSYS procedure. And with simulating the status of composite foundation under the working load, the project properties of composite foundation are investigated. Further more, analysis on the impacts of different pile parameters on stress and settlement of composite foundation have been carried out. In the end, the optimization scheme of composite foundation design has been proposed.

Using time domain reflectometry in triaxial testing

2000 ◽  
Vol 37 (6) ◽  
pp. 1325-1331
Author(s):  
J LH Grozic ◽  
M E Lefebvre ◽  
P K Robertson ◽  
N R Morgenstern
Keyword(s):  
Cyclic Loading ◽  
Water Content ◽  
Time Domain ◽  
Void Ratio ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Degree Of Saturation ◽  
Triaxial Testing ◽  
Empirical Correlations ◽  
Static And Cyclic Loading

Time domain reflectometry (TDR) can be used to determine the volumetric water content of soils. This note describes the utilization of a TDR miniprobe in triaxial testing. The TDR performance was examined with a series of tests that not only proved its reliability but also resulted in two empirical correlations. Using these correlations, the degree of saturation and volumetric water content during triaxial testing could be determined. The TDR was then put to use in a laboratory program designed to investigate the response of loose gassy sand under static and cyclic loading. Because of the TDR measurements it was possible to determine the degree of saturation and void ratio of the gassy specimens. The TDR miniprobe proved to be accurate, simple to use, and inexpensive to build.Key words: time domain reflectometry, TDR, triaxial testing, gassy, unsaturated.

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