Kind Of Pile Research Articles

A case study on the bearing characteristics of a bottom uplift pile in a layered foundation

The bottom uplift pile, which has been applied in practical projects, has the following advantages: the pile body is not easy to crack, good bearing characteristics, and small displacement of the pile top. Based on the bearing capacity test of foundation piles in the third stage expansion project of Lanzhou Zhongchuan International Airport, the upper part pile of the self-balancing test method was used to simulate the bottom uplift pile, and the anchor piles in the anchor pile method were regarded as normal uplift piles. The bearing characteristics of the bottom uplift pile in a layered foundation were studied by comparing these two kinds of piles. The results show that under the same displacement of the pile top, the ultimate uplift bearing capacity of the bottom uplift pile can be more than twice that of the normal uplift pile because of the fully exerted frictional resistance of the soil at the bottom of the pile, the Poisson effect of the pile body and the avoidance of the influence of pile body deformation on the pile top displacement. The maximum axial force of the bottom uplift pile appears at the bottom of the pile and gradually decreases from the bottom to the top, which is opposite to that of the normal uplift pile. The properties and thickness of the soil layers around the pile have a great influence on the distribution curves of the frictional resistance along the pile length of the two kinds of uplift piles. With changing soil layer conditions, the distribution curve may be a "parabola", a "straight line" or a "double line". The soil property plays a decisive role in the frictional resistance, which may cause softening. The influence of the pile diameter on the ultimate uplift bearing capacity is greater than that of the pile length, while the elastic modulus of the pile has little influence.

The slenderness ratio effect on the response of closed-end pipe piles in liquefied and non-liquefied soil layers under coupled static-seismic loading

AbstractThis study presents the findings of a 3D finite element modeling on the performance of a single pile under various slenderness ratios (25, 50, 75, 100). These percentages were assigned to cover the most commonly configuration used in such kind of piles. The effect of the soil condition (dry and saturated) on the pile response was also investigated. The pile was modeled as a linear elastic, the surrounded dry soil layers were simulated by adopting a modified Mohr-Coulomb model, and the saturated soil layers were simulated by the modified UBCSAND model. The soil-pile interaction was represented by interface elements with a reduction factor (R) of 0.6 in the loose sand layer and 0.7 in the dense sand layer. The study was compared with the findings of 1g shaking table tests which were performed with a slenderness ratio of 25. In the validation case, there was a clear correlation between the laboratory findings and the numerical analyses. It was observed that the failure mechanism is influenced by the soil condition and the slenderness ratio to some extent. Under the dry soil condition, no base pile deformation was observed; However, tip pile movement was observed under the saturated soil condition with pile slenderness ratios of 25 and 50. The findings of this study are also aimed to include an approximation of the long-term deformations at the ground surface which has experienced shaking.

Investigation on hydrodynamic performance of an environmentally friendly pile breakwater

In this paper, a type of pile breakwater is studied in a configuration that can provide an effective shore protection structure. While, the rubble mound breakwaters are the most common type, but they suffer from a number of shortcomings including the interruption of water that may lead to deterioration of water quality and corresponding environmental problems. The breakwater of this study with rows of piles can be used against sea waves, as an alternative. Its hydraulic performance, including wave reflection and transmission, shear stresses, pressure measurements, drag and inertia coefficients are investigated. In the first step, the hydrodynamics around the mono-piles with square cross-sections are inspected. The parametric equations are developed to measure the optimal orientation of the piles. As evidenced in the literature, relatively limited works have been carried out on this kind of piles. Also, the performance of the considered pile breakwaters are evaluated. To do this, the numerical results are calibrated and validated by experimentation. It is observed that the group piles with the square cross-section in optimum conditions, could have a higher value of reflection almost between 7 even to almost 30 percent, than other considered conditions with mild and short waves. It can be related to the effect of the square piles edges on the separation process of the flow.

Design and Manufacturing Loading Rig Machine for Testing Screw Pile Models

The main objective of this paper is to design, manufacturing and testing of new loading rig machine to install and testing (i.e. compression and tension load capacity) of screw pile models in both cohesive and cohesionless soil layers. The mainframe was fabricated from thick steel sections, 8mm steel plates that welded together to construct a heavy and strong frame, that able to resist the expected loads during installation (linear and rotational movement at the same time) and testing of the screw pile models (model of loading test). Two independent gearbox motors (actuators) are used to supply the rotational and vertical movement. To provide precise control of velocity, the master gearbox motor, that can convert the rotary motion to a linear motion for vertical displacement along two screw bars via two ball screw systems, and four stainless guided rods to prevent rotation or inclination the bearing plate (rig) which manufactured from high stiffness stainless-steel was used. The second gearbox motor (‘slave’) mounted on the bottom loading plate that rotates the multi-plate screw pile. It was observed that the measured compression and tension load capacity of screw pile models illustrated the actual behavior of such kind of piles and this machine can be used in both conventional piles (i.e. pipe piles) and screw pile model.

Field test on Ultimate bearing capacity of Composite Pile made up of Jet-mixing Cement and PHC Pile with Core Concrete

Composite pile made up of jet-mixing cement and PHC pile with core concrete (CPCP) is a new kind of pile. It is formed by inserting PHC core promptly into the cement soil mixing pile. According to the single pile static load test and PHC pile cement soil bond strength test, differences between CPCP and pipe pile in bearing capacity and coordination deformation mechanism are studied. The results show that presence of peripheral cement soil has greatly improved the bearing capacity of CPCP. Three different loading modes have no obvious effect on CPCP bearing capacity, but the more significant effects on settlement. When the cement soil and soil interface destroyed, pile and cement soil interface friction resistance is much smaller than the bond strength, indicating that the bond strength can ensure coordination between the pile and cement soil. On this basis, the design formula for calculating the bearing capacity of CPCP pile is proposed. Comparing calculated values with field measured values, it has been found that the results are less error and the formula has a certain reliability in the calculation of vertical ultimate bearing capacity of CPCP pile, providing a certain reference for the design and calculation of this type of piles.

Testing of open section drilled C-pile and CT-pile wall

Micropile developments have greatly advanced over the last two decades and new kinds of piles have been created to meet different challenges in foundation works. This paper describes an open section steel C-pile. A C-pile can be used for lightly loaded foundations to reduce cost and improve environmental efficiency. This C-pile has been developed further for use as a vertical drilled ‘sheet pile wall’. In this application, a T-profile is welded to a single C-pile. This combined profile allows the piles to be connected to each other and to form a wall – a CT-pile wall. When cement grouting is used to infill the hollow sections, a moderately watertight structure with higher stiffness is created. This paper presents the results of an installation test conducted on a CT-pile wall. The results from the test showed that the CT-pile wall performed well, and the deformations in the wall and behind the wall were at an acceptable level. The CT-pile wall is similar to a moderately light sheet pile wall and is expected to provide relatively good watertightness.

Experimental Study of Shear Behavior of Interfaces Between Crushed Sandstone-Mudstone Particle Mixture and Smooth Steel Plate

Shear behavior of interfaces between steel and soil composed of crushed sandstone and mudstone greatly influences the side resistance of RSCFST pile, a new kind of pile widely used in deep water wharf in western China. This paper presents the results of experimental studies on the shearing behavior of the soil-steel interfaces. Strain-controlled shearing tests are carried out with a direct shear apparatus under constant normal load condition. The influence of water content on the response of the interfaces is investigated. The test results reveal nonlinear relations between the shear strain and the shear stress. It indicates that the shear strength of the interfaces obey the Mohr-Coulomb criterion. The strength parameters, including cohesive force and friction angle are influenced greatly by the soil properties as well.

Comprehensive Evaluation on Testing Quality of Cement Mixing Pile of Weak Subgrade by Core Drilling Method

Cement mixing pile is widely used in weak subgrade treatment and the quality of it has a direct bearing on the treatment effect of weak subgrade. Core drilling method is an effective method of testing quality of cement mixing pile. However, there are certain deficiencies in quality evaluation method of this kind of piles during practical application. In this paper, auxiliary evaluation criterion, established through standard test pile and combining with subgrade testing engineering is applied to the quality evaluation on test pile with construction deficiency after being combined with existing evaluation system. The result shows that the adoption of evaluation result of improved quality evaluation system can well reflect the pile construction quality of the test pile under complicated soil layer condition and is a reliable method of pile quality evaluation.

Analysis the Bearing Force Characteristic of the New Cast-in-Place Concrete Pile with Half-Screwed

Half-screwed pile is a new kind of pile. Because of the unique design of variable cross-section, bearing principle and working traits are much more complex than the traditional linear pile. The vertical load transmission mechanism thoroughly is analyzed about half-screwed pile based on the static load experiment results. Researching its work performance, load transfer mechanism, the force mode, has important theoretical and practical significance.

Analysis of the Results of Pile Trial for the Subsidiary High-Rise Building of the Shandong Provincial Center for Culture and Art

The high-rise towers and podium of the Shandong Provincial Center for Culture and Art adopt post-grouting drilling bored pile (pressure loaded pile) and compaction-under reamed bored pile (uplift pile) respectively. Based on an off-site self-balanced static-load test of the two kinds of piles, the bearing capacity, displacement, technology for pile-forming, construction period, and engineering cost are presented in detail, and the design basis for the two piles obtaining high bearing capacity on soft soil is also preliminarily put forward. The results of this study provides a design reference for the similar projects in the western new district of Jinan City.

SOME ASPECTS OF JOINING PILES

Abstract Application of the pile joining is a new solution of the complex pile foundation including the base, made in the ground, and the piles joining the base with the girt. This kind of piles can be used for foundation under special geological conditions (proglacial stream valleys) for foundation reinforcement of the existing buildings and new foundations. The solution proposed may be used in the swelling soils. In this work, the possibilities of applying joining piles in different soils, like fine sands, silts, clays, clay shale, sandstones, which can be the foundation for the pales have been considered.

PERILAKU TIANG BOR PENOPANG INFRASTRUKTUR PADA TANAH LUNAK AKIBAT BEBAN STATIK

Bored piles have been used to support transportation infrastructures (offices, a terminal building, power house, warehouses and workshop) in a harbor. The bored piles were penetrated into mostly old alluvial deposits and dilluvial deposits of very stiff marine clay with traces of shell debris. A bored pile was tested as part of this research program to verify the accuracy of the predicted pile capacities. The proposed static prediction capacity methods include Meyerhof, a, b and l methods. The results of the analysis show that Meyerhof method (1951) with inputs of laboratory test data provides closely agreement with static loading test results. The other methods give somewhat conservative prediction. This paper discusses bearing capacity analysis of bored piles based on soil characteristics and static loading test results. Results of the analysis indicate that the bored piles capable of resisting load transmitted from the upper structure. The research will be of interest to many practicing engineers using this kind of piles.

Characteristics of Cast-<i>InSitu</i> Concrete Pipe Pile under Lateral Load

The cast-in-situ concrete pipe pile is a new kind of pile used widely in China to improve the soft ground. In this paper, the general introduction of this pile was given, mainly including the pile driving machine, the technique of pile working and the structure of pile. At last, one in situ test of this pile under lateral load were given, the characteristics of displacement of pile body and displacement of pile top were analyzed. These results can give a reference for practice project.

Action of Internal Cnoidal Wave on Pile

The numerical simulation of flow around the pile acted by the internal cnoidal waves has been made by building two-dimensional numerical wave flume based on FLUENT software. Internal cnoidal waves are generated by push-pedal method and the free surface is captured by VOF method. The wave shapes with different amplitudes and different periods are obtained. Moreover, the force of the internal cnoidal wave with specific period and amplitude on different kinds of piles in three-dimension are simulated. The trend of inertial force and the viscous force on the piles is analyzed and the total wave forces on piles with different shape are compared.

Optical Measurement of Sand Deformation around a Laterally Loaded Pile

Abstract A sand displacement field around a laterally loaded pile is measured using an image processing technique called digital image correlation. An optical system consisting of a camera, a loading frame, and a computer is developed to capture soil movement during laterally loading the pile. Two images, before and after a deformation, are used to calculate the soil displacement field. Two kinds of piles are used in the tests: one squared-section pile and the other a circular one. Dry loose sand samples are used to simplify the problem. The displacement and strain fields obtained in this study are similar to the ones reported from the field. A trapezoidal strain wedge is measured in sand in front of the laterally loaded pile. The strain wedge develops from the pile edges. The failure planes form an angle with the horizontal, which varies between approximately two-thirds of the frictional angle of soil for the square pile and three-fourths for the circular pile.