Capacity Of Single Pile Research Articles

Influence of soil type on load carrying capacity of single piles

Influence of soil type on load carrying capacity of single piles

Experimental Study on Bearing Characteristics and Soil Deformation of Necking Pile with Cap Using Transparent Soils Technology

This paper will employ the transparent soil experiment technology to explore the influences of shallow necking on the vertical bearing capacity of single pile with cap. Model experiment is carried out on one intact pile and nine shallow necking piles. The load-settlement curves of all piles are obtained, which are used to study bearing characteristics of piles. The displacement fields of soil around piles are employed to investigate the reasons for the loss of vertical bearing capacity of piles with shallow necking. The vertical bearing capacity is greatly reduced which is caused by shallow necking. When the axial dimension of necking is the same, the larger the radial size is, the greater the loss of vertical bearing capacity is. When the radial dimension of necking is the same, the greater the axial size is, the greater the loss of vertical bearing capacity is. The soil near the pile shaft and under the pile cap produces a large area of vertical downward deformation, which causes the relative displacement between the pile shaft and the soil to greatly reduce. Therefore, it is easy that the necking piles with caps develop negative friction, which causes the vertical bearing capacity of piles to reduce. When the radial dimension of the shallow necking is 80% of pile diameter, the pile is easy to be damaged.

Influence of Geometry and Separation Walls on The Behaviours of Pull-out Pipe Piles Embedded in Sandy Soil

Predicting of piles capacity and their behavior is always an important and serious problem for a safe geotechnical engineering design. In the present study, experimental model tests have been conducted on a single steel pipe piles driven in sandy soil and subjected to pull-out force. The experimental tests were conducted on vertical open-ended piles with circular and square cross-sectional area and three various diameters 3 cm, 4 cm and 5 cm in a steel soil box have been used. The tested pile’s model has embedment with three penetration ratios (PR=L/D) of 10, 15 and 20. All tests were done in medium density soil (Dr = 50%) with open ended pipe pile to study the effect of pile geometry on pile behavior, and three other tests were conducted on the 5cm diameter and 10 penetration ratio in medium soil density to study the importance of addition of separating wall. The study discovered that the capacity of single piles with circle cross-section area under pull-out force increasing by 211% and 458% with the increasing of pile diameter (width) from 3cm to 4cm and 5cm respectively, and increasing by 210%, 448% and by 112%, 288%. Also, by 79% and 211% with increasing penetrating ratio (PR) from 10 to 15 and 20 for diameters 3cm, 4cm and 5cm respectively, with respect to reference pile. And the same behavior for square cross-section pipe pile, when the pull-out capacity increasing with the increase of pile width and penetration ratio due to the increasing in the friction area. Besides that, It was also found that the separation walls increased the coefficient of lateral pressure in addition to the friction area. At the same time, there are an optimum number of separation walls that can be used to increase the pile pull-out capacity and that when using three separation walls.

Comparison and analysis of conversion methods for self-balancing test of pile bearing capacity

The principle and method of self-balancing test are introduced briefly. In this article, through comparison of common Q-S curve of equivalent transformation to transform from the balance of the measured load-displacement curve for the traditional method of load - displacement curve, puts forward the advantages and disadvantages of each, through the three bored piles in static load test of pile reaction from balance to detect vertical compressive ultimate bearing capacity of single pile is in line with the requirements and compare the load-displacement curve after conversion. Some problems of the self-balancing method in engineering are pointed out, which is of certain reference value to the popularization and application of the self-balancing test of pile bearing capacity.

An experimental study of rough single pile and pile group under uplift loading in sand

Foundation systems of specific structures such as high-voltage power lines, communication towers, long factory chimneys, sea platforms, columns carrying the advertising boards and signs in freeways and railways are subjected to different loads. These structures are also under the influence of uplift load and the foundation systems should be designed according to the factors affecting the uplift capacity. In this study, the uplift capacity of a rough single pile and pile group embedded in sand is investigated, experimentally. The uplift capacities of a single pile and pile group configuration of 2 × 2 under the effect of various parameters such as pile embedment ratio (L/D), spacing ratio between the piles (S/D) and relative density of sand (Dr) are examined by using a rough steel pile in 25 mm diameter with circular geometry. Furthermore, it is aimed that the uplift capacity of each pile is determined by being connected a load cell to each pile in the group. The value of (S/D)opt is determined to be affected by the relative density of sand, and the interaction between piles eliminates in larger S/D in dense soil. It is observed that the uplift capacity increases considerably with the increase of all investigated parameters.

A simplified calculation method for axial cyclic degradation of offshore wind turbine foundations in clay

Pile foundation is the most popular option for the foundation of offshore wind turbines. The degradation of stiffness and bearing capacity of pile foundation induced by cyclic loading will be harmful for structure safety. In this article, a modified undrained elastic–plastic model considering the cyclic degradation of clay soil is proposed, and a simplified calculation method (SCM) based on shear displacement method is presented to calculate the axial degradated capacity of a single pile foundation for offshore wind turbines resisting cyclic loadings. The conception of plastic zone thickness Rp is introduced to obtain the function between accumulated plastic strain and displacement of soil around pile side. The axial ultimate capacity of single piles under axial cyclic loading calculated by this simplified analysis have a good consistency with the results from the finite element analysis, which verifies the accuracy and reliability of this method. As an instance, the behavior of pile foundation of an offshore wind farm under cyclic load is studied using the proposed numerical method and SCM. This simplified method may provide valuable reference for engineering design.

Ultimate Lateral Load Capacity of Piles in Soils Contaminated with Industrial Wastewater

The present study devoted to determine the ultimate lateral carrying capacity of piles foundation in contaminated clayey soils and subjected to lateral cyclical loading. Two methods have been used to calculate the lateral carrying capacity of piles foundation; the first one is two-line slopes intersection method (TLSI) and the second method is a modified model of soil degradation. The model proposed by Heerama and then developed by Smith has been modified to take into consideration the effects of heavy loads and soil contamination. The ultimate lateral carrying capacity of single pile and piles group (2×2) driven into samples of contaminated clayey soils have been calculated by using the two methods. Clayey soil samples are contaminated with four percentages of industrial wastewater (10, 20, 40 and 100) % of the distilled water used in the soaking process, the soaking procedure of soil samples have been proceeded for 30 days. Also, two ratios of eccentricity to embedded length (e/L = 0.25 and 0.5) have been examined. The results obtained from two analytical methods are well agreed with those obtained experimentally. The ultimate lateral carrying capacity, Pu (analytical) /Pu (experimentally) ranged from (75-8) % and (77-80) % of single pile with e/L = 0.25 and 0.5 respectively. In the piles group the ratio ranged (67-80) % and (71-79) % for e/L = 0.25 and 0.5 respectively.

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.

Analysis on Pore-Forming Pouring Pile Construction Technology of House Building Project

Compared with the in-place pile, the pore-forming pouring pile is more simple and convenient, with a wider range of construction. In the actual construction process, it is able to pass through complex bottom layer and water layer underground without very high requirements in equipment. The actual bearing capacity of single pile is very strong, so that it can be better to adapt to the actual needs of different scales or the different geological conditions in building. And it has been promoted and used greatly in building construction work [1]. This paper introduces the concept of the pore-forming pouring pile technology, analyzes the pore-forming construction technology and the pile construction technology, then talks about prevention problems of the pore-forming pouring pile construction in House Building Project, at last draws a conclusion that the pore-forming pouring pile technology is the most basic construction technology and is the most effective and convenient way of construction.

Finite Element Analysis of the Influence About the Space Between Bearing Expanded-Plate to the Bearing Capacity of Single Pile of the MEEP Pile

In this paper, by ANSYS software it is built that a computer simulation analyzing model according to the finite element method, which is analyzed that the failure mechanism of the main pile and the soil around the bearing expanded-plate of the Multi-Expanded-plates pile(the MEEP pile), it is qualitatively determined that the space between the bearing expanded-plates affect the bearing capacity of the single pile of the MEEP pile, and of which the lower limiting value is put forward, in order to provide the theoretical support to the actual design of the MEEP pile

The Research on the Affect of Collapse State and Bearing Capacity of the Soil Layer Properties Adjacent to the Bearing Plate of the Multi-Extruded-Expanded-Plates Pile

This paper introduces the research status and analysis of the Multi-Extruded-Expanded-Plates pile (the MEEP pile) at home and abroad, by studying when the plate of pile embedded in different characteristics soil layer, the thickness, physical properties of upper and lower soil layer adjacent to the soil with plate cause the influence on soil break and bearing capacity of the soil layer with plate, analyzing the work together with pile and soil in different soil layer, providing a theoretical basis to improve the calculation formula of bearing capacity of single pile, ensuring the rationality and reliability of the design of the MEEP pile.

Analyzing on Bearing Performance Influence Factors of Step Cross-Section Pipe Pile

In order to improve the bearing behavior and the bearing capacity of single pipe pile, the technology of step cross-section pipe-pile is proposed.Based on FLAC3D, the finite difference model of the pile-soil interaction established,bearing behaviors of step cross-section pipe pile and unimate cross-section pipe pile is studied comparatively and bearing performance influence factors of step cross-section pipe pile is discussed.The results show that the bearing capacity of step cross-section pipe pile is much higher than unimate cross-section pipe pile in the same geological conditions and material dosage. For layered foundation, the bearing capacity of single pile may be improved by setting variable cross-section pile joint in relatively hard soil. But the depth of joint embedded in hard soil has little influence on bearing capacity of single pile.There is an obvious effect on increasing capacity of single pile by improving soil properties of soft soil surrounding pile.

A Study of PHC Pipe Pile Vertical Ultimate Bearing Capacity Calcula-tion Method and its Numerical Simulation Analysis

According to the PHC pipe pile design of Xinwan Plaza, Huaiyuan, Anhui and pile test results of static sounding method and experience method using the ultimate bearing capacity of single pile are calculated, considering the effect of soil plug the influence of vertical ultimate bearing capacity of single pile, and the formula for calculating the lateral resistance and end resistance, static sounding method and the correction formula to calculate the bearing capacity calculated results was coincident with the results of test pile. Combining with the project of Xinwan Plaza, Huaiyuan, Anhui, through the static load test, a study of the load transfer mechanism of PHC pipe pile, analyzes the vertical load, the change rule of the settlement of pile body and pile and the use of finite difference software FLAC3D simulation of the PHC pipe pile static load test, the simulation results agreed with the measured load-settlement curve.

The Research on the Ultimate Bearing Capacity of Soil around the Push-Extend Multi-under-Reamed Pile at Sliding Failure State

In the paper, the existing unreasonable place of the calculation formula of the bearing capacity of single pile is put forward. Through analyzing the failure mechanism of the soil up and under the Multi-under-reamed, the method for calculating the ultimate bearing capacity of soil around the PEMUR pile can be determined by using the slide-line theory, and the calculation formula of the bearing capacity of single pile of the PEMUR pile is further revised and perfected.

Analysis of Diameter of the Bearing Push-Extend Reamed in the Size of the Influence of the PEMUR Pile Bearing Capacity of Single Pile

As the change of diameter of the bearing push-extend reamed in the size, failure pattern of soil mass around the PEMUR pile has changes. Based on the finite element method, simulated analysis has been conducted about normal stress and shear stress of soil around pile under different plate diameter size, which has qualitatively identified that the PEMUR pile bearing capacity of single pile has influence on disc diameter, application for this type of pile design provides a theoretical basis.

The Review on the Modified Exponential Model in the Fitting of Loading-Settlement Curves of Single Pile

According to optimized fitting analysis for measured data in static load test of 22 different types of single piles, a new modified exponential model was proposed by authors in this paper. In comparison between the hyperbolic model and the integrated exponential curve model, the correlativity coefficients R of the modified exponential model were over 0.996. The fitting effect of the model of proposed in this paper is better than that of other models above-mentioned. The deviations between fitting and measured data in static load test for single pile was small, especially, in the tail pasts of fitting curves, the mean deviations of 2 test pile given in the paper are 1.61% and 1.99% respectively. The modified exponential model can be better described Q-S curves of single piles. It can be used to better evaluate the ultimate bearing capacity of single piles.

Axial Force Analysis of the Single Pile Based on FLAC3D

Complex interaction mechanism of pile and soil, pile load transfer analysis is difficult. On the basis of analyzing the load transfer mechanism of the friction pile, using the FLAC3D analysis on the initial ground stress state of equilibrium , axial load under the action of pile axial force and displacement, got the ultimate load bearing capacity of single pile and the stress of the contact surface. Analysis results show that the load and displacement in a certain stage into a proportional relationship. Also shows that simulation is feasible and provide a reliable method for the analysis of pile groups.

The Discussion about Improving the Bearing Capacity of Single Pile for Bored Pile in Sandy and Silt Layer

The bored pile which have the unique advantage in having no noise, no shake, no upheaval, no sides way in the process of construction has became into one of the most widely used pile foundations in high heavy construction in Inner Mongolia region. Through an engineering project of bored piles in Inner Mongolia region, this article takes an analysis for bearing behavior of the bored piles in sandy and silt layer in this region. It also discusses the influence construction technology on pile-end ultimate resistance and the reasonable range of reduction factor of the ultimate resistance. When the soil layers structure is similar, it could improve bearing capacity of single pile for bored pile by utilizing the supporting layer and substratums optional regrouping. Utilize traditional single pile bearing capacity theory formula calculating and the static load test results it takes an analysis, finding out the approach of improving the bearing capacity of single pile for bored pile in sandy and silt layer. So we could find the optimization design for pile foundation bearing capacity of bored pile and thus promote the improvement in bored piles theory research and engineering application level in Inner Mongolia region and provide theory and engineering design experience.

Parametric study of pile cap lateral resistance: finite element analysis

Analytical studies using finite element analysis of pile cap resistance under lateral load is seldom reported in literature. Recently, presents the results of experimental study on model piles to show the effect of pile cap elevation below the ground surface and pile spacing on lateral resistance of single pile and pile groups driven in sand. From their parametric study, they concluded that the lateral carrying capacity of single pile and pile groups increase as the pile cap depth below the ground surface increases and as the spacing between piles in the group increases. The objective of this study is to study pile–soil–cap interaction under lateral load considering different influences parameter and thus quantifying the lateral resistance for different conditions. Finite element modeling and analysis is performed for three different spacings, namely 3D, 5D, and 9D for RCC pile with 300, 400, and 500 mm diameter. It is observed that pile cap has lateral resistance varying from 35·42 to 44·06% implies good agreement with the findings of .

Bearing capacity of single pile and in-flight T-bar penetration for centrifuge modeling of land subsidence caused by the interaction of high-rise buildings

With an increasing number of high-rise buildings in major cities worldwide, land subsidence induced by the interaction between closely-spaced buildings in soft soil areas has become a major challenge for many researchers. The paper considers the interaction of high-rise buildings by determining the bearing capacity of a single pile in the centrifuge model test. The T-bar penetration test was conducted in flight to measure the shear strength of the soft soil, together with vane shear tests when the model had slowed down. By analyzing the relationship curves between land subsidence and the centrifuge acceleration, the allowable bearing capacity of a single pile for the high-rise building was obtained. It is considered that such analysis is a more appropriate method of determining the pile requirements for groups of adjacent high-rise buildings in soft soil areas.