scholarly journals Field Tests of Super-Long and Large-Diameter Drilled Shaft Pile Foundations

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Peisen Wang ◽  
Hongyan Ding ◽  
Jialin Zhou ◽  
Wenjun Hu ◽  
Xuechen Gu ◽  
...  
Keyword(s):  
Load Transfer ◽  
Large Diameter ◽  
Soil Layer ◽  
Field Tests ◽  
Load Test ◽  
Pile Foundations ◽  
Static Load Test ◽  
Mutual Compensation ◽  
Shaft Resistance ◽  
Pile Diameter

This study investigated the compressive behaviour of super-long pile foundations with large diameters. Three 52 m, 73 m, and 83 m long piles with a diameter of 1500 mm, 1500 mm, and 1800 mm were cast and tested, respectively. Given that large loading was required, an improved compressive static load test was introduced, and the load transfer mechanism, shaft resistance development, and distribution were analysed. This study found that the transferred load decreased along the pile during each applied load, but the gradients were different. For most layers, when increasing the load, the shaft resistance developed in the upper layers first, while the shaft resistance from the lower part did not always fully develop. Moreover, the “mutual compensation” phenomenon was discovered, which was when the shaft softening occurred from one soil layer, the shaft hardening of the other soil would occur simultaneously. Under consideration of the soil layer differences around these piles, it was recommended that shaft and base grouting should be applied on 52 m and 73 m piles, while only shaft grouting should be applied on the 83 m pile. For this longest pile design, whose toe resistance was discovered to be very small, increasing the pile length was not appropriate; thus, it was preferable to increase the pile diameter to increase the ultimate bearing capacity.

Research on Uplift Static Load Test of Large-Diameter Steel Pipe Pile Based on Mechanics

2012 ◽  
Vol 256-259 ◽  
pp. 410-415 ◽  
Author(s):  
Kai Cheng Huo ◽  
Xu Qin ◽  
Huan Huan Yue
Keyword(s):  
Static Load ◽  
Large Diameter ◽  
Load Test ◽  
Steel Pipe ◽  
Hyperbolic Model ◽  
Static Load Test ◽  
Pipe Pile ◽  
Shaft Resistance ◽  
S Curve ◽  
Steel Pipe Pile

Combined with the uplift static load test of large-diameter steel pipe pile in Xiangshan Port bridge of Ningbo, make analysis of Q-s curve and s-lgt curve, axial force distribution curve and unit shaft resistance, revealing the uplift characteristic of the steel pipe pile. The analyses show that the uplift steel pipe pile is pure friction pile, the uplift load is decreased downward through the axial force of pile body, the shaft resistance gradually plays from top to bottom and play completely in the upper soil. Moreover, it has used hyperbolic model to fit the measured Q-s curve by Matlab software, and the fitting precision is high. Then make the hyperbolic model non-dimensional, and attempt to predict ultimate bearing capacity using the maximum curvature point of the non-dimensional hyperbolic model, to get some mechanical characteristic.

scholarly journals Field study on axial bearing capacity and load transfer characteristic of waveform micropile

2018 ◽  
Vol 55 (5) ◽  
pp. 653-665 ◽  
Author(s):  
Young-Eun Jang ◽  
Jin-Tae Han
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Soil Layer ◽  
Field Tests ◽  
Transfer Characteristic ◽  
Construction Method ◽  
Shaft Resistance ◽  
Jet Grouting ◽  
Loading Tests ◽  
Load Transfer Analysis

The waveform micropile is an advanced construction method that combines the concept of the conventional micropile with the jet grouting method. This new form of micropile was developed to improve shaft resistance, and has enabled a higher bearing capacity and greater cost efficiency. Two field tests were conducted to examine field applicability and to verify the effects of bearing capacity enhancement. In particular, waveform micropile construction using the jet grouting method was performed to evaluate the viability of waveform micropile installation. After testing, the surrounding ground was excavated to check the shape of the waveform micropile. The result showed that waveform micropiles can be installed by adjusting the grouting time and pressure. In the loading tests, the bearing capacity of the waveform micropile increased by 1.4–2.3 times that of the conventional micropile, depending on the shape of the micropile. The load transfer analysis using the strain gauge data showed that the waveform micropile increases the shaft resistance in the soil layer. This not only decreases pile settlement, but also contributes to the increase of overall bearing capacity. The overall results clearly demonstrate that the waveform micropile is an enhanced construction method that can improve bearing capacity.

Back-Analysis for Design Parameters of Large Diameter Bored Piles

2013 ◽  
Vol 671-674 ◽  
pp. 186-189
Author(s):  
Werasak Raongjant ◽  
Meng Jing
Keyword(s):  
Test Data ◽  
Load Transfer ◽  
Static Load ◽  
Large Diameter ◽  
Back Analysis ◽  
Load Test ◽  
Design Parameters ◽  
Static Load Test ◽  
Friction Resistance ◽  
Bored Piles

Field test data from three instrumented large diameter bored piles in Pattaya city of Thailand were analyzed to study the behavior of load transfer mechanism from the pile to soil. The pile load test data were obtained from conventional static load test. These bored piles used for conventional static load test have the same diameter of 0.80 m and different length in the range of 25 m to 32 m. Results from back-analysis found that the skin friction resistance, β, has the value between 0.20 and 0.64 and the bearing capacity at end of piles, Nq, which is in the range of 10 to150, is much lower than the theoretical values proposed by other researchers before.

Vertical Loading Test on the Bearing Capacity of Large-Diameter Filling-Piles in the Mudstone and Sandstone Foundation

2013 ◽  
Vol 639-640 ◽  
pp. 587-592 ◽  
Author(s):  
Hui Yang ◽  
Xue Liang Jiang ◽  
Jun Fu
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Large Diameter ◽  
Load Test ◽  
Sediment Thickness ◽  
Loading Test ◽  
Friction Resistance ◽  
Vertical Loading ◽  
Pile Diameter ◽  
Side Friction

Based on the vertical loading test results of large-diameter filling pile near an electric factory in the sandstone and mudstone foundation, the load transfer mechanism and vertical loading bearing behavior of the pile were discussed. The analysis shows that the pile mainly behaves as friction piles and the vertical bearing capacity is mainly supplied by side friction resistance. The pile side friction is related to the section displacement of pile, the pile load and the soil characteristic. The pile end resistence is related to pile end settlement, pile diameter, rock-socketed length,rock elasticity modulus of pile end, sediment thickness and pile construction technical. The pile end resistence linearly increases with the settlement of pile end. In tis paper, the dead-load test is recommended in determination the pile bearing capacity and the sediment thickness should be strictly controlled in order to meet the standard. In the intermediary weathered sand-mudstone, the pile end should inset two times of pile diameter for pile whose diameter is 800mm. The pile end should inset 2 meters for pile whose diameter is 1500mm.

Experimental Study of the Rotary Filling Piles with Large-Diameter under the Axial Load

2012 ◽  
Vol 594-597 ◽  
pp. 527-531
Author(s):  
Wan Qing Zhou ◽  
Shun Pei Ouyang
Keyword(s):  
Experimental Study ◽  
Axial Load ◽  
Load Transfer ◽  
Soft Soil ◽  
Large Diameter ◽  
Shaft Resistance ◽  
Tip Resistance ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Deep Soft Soil

Based on the experimental study of rotary filling piles with large diameter subjected to axial load in deep soft soil, the bearing capacity behavior and load transfer mechanism were discussed. Results show that in deep soft soil foundation, the super–long piles behave as end-bearing frictional piles. The exertion of the shaft resistance is not synchronized. The upper layer of soil is exerted prior to the lower part of soil. Meanwhile, the exertion of shaft resistance is prior to the tip resistance. For the different soil and the different depth of the same layer of soil, shaft resistance is different.

Numerical investigation of the monotonic drained lateral behaviour of large diameter rigid piles in medium dense uniform sand

Géotechnique ◽  
2021 ◽  
pp. 1-39
Author(s):  
Huan Wang ◽  
M. Fraser Bransby ◽  
Barry M. Lehane ◽  
Lizhong Wang ◽  
Yi Hong
Keyword(s):  
Numerical Investigation ◽  
Load Transfer ◽  
Large Diameter ◽  
Offshore Wind ◽  
Soil Pressure ◽  
Lateral Capacity ◽  
Pile Diameter ◽  
Centrifuge Tests ◽  
Lateral Response ◽  
Loading Eccentricity

This paper presents a numerical investigation of the monotonic lateral response of large diameter monopiles in drained sand with configurations typical of those employed to support offshore wind turbines. Results from new centrifuge tests using instrumented monopiles in uniform dry sand deposits are first presented and used to illustrate the suitability of an advanced hypoplastic constitutive model to represent the sand in finite element analyses of the experiments. These analyses are then extended to examine the influence of pile diameter and loading eccentricity on the lateral response of rigid monopiles. The results show no dependency of suitably normalized lateral load transfer curves on the pile diameter and loading eccentricity. It is also shown that, in a given uniform sand, the profile with depth of net soil pressure at ultimate lateral capacity is independent of the pile diameter because of the insensitivity of the depth to the rotation centre for a rigid pile. A normalization method is subsequently proposed which unifies the load-deflection responses of different diameter rigid piles at a given load eccentricity.

The Calculation of Critical Pile Length for Super-Long Pile Based on Settlement Control

2011 ◽  
Vol 71-78 ◽  
pp. 4179-4183
Author(s):  
Li Nong Xia ◽  
Yun Dong Miao ◽  
Tie Qiang Tan ◽  
Xin Tong
Keyword(s):  
Shear Deformation ◽  
Field Measurement ◽  
Load Transfer ◽  
Working Condition ◽  
Transfer Model ◽  
Shaft Resistance ◽  
Pile Diameter ◽  
Pile Settlement ◽  
Deformation Transfer ◽  
Pile Length

Based on the analysis of character of load-transfer of super-long pile, for the purpose of pile settlement control, critical pile length for single friction super-long pile was calculated by Cooke’s shear deformation-transfer model, because the assumption of Cooke’s model is similar with working condition of super-long pile. In the analysis, compression of pile is taken into account. Then, the design chart of critical pile length for super-long pile is provided for normal design index. Lastly, the critical pile length of an engineering example is analysed by the method, the calculated results have agreed well with the field measurement. The analysis show that critical pile length is greatly concerned with ratio of Young’s module of pile and soil, the greater the ratio is, longer the critical pile length is. Pile diameter also affects the critical pile length, the larger the diameter is, longer the critical pile length is. In addition, the critical pile length of super-long pile is concerned with shaft resistance distribution along the pile.

FULL SCALE STATIC LOAD TEST ON THE SPIDER NET SYSTEM

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Helmy Darjanto ◽  
Masyhur Irsyam ◽  
Sri Prabandiyani Retno
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Static Load ◽  
Full Scale ◽  
Load Test ◽  
Static Load Test ◽  
Specific Element ◽  
Soil Stratum ◽  
Applied Loading ◽  
Shallow Footing

The Spider Net System Footing (SNSF) is a raft foundation system that commonly used in Indonesia. It contains a plate, downward ribs system for reinforcement, and the compacted filled soil. The ribs are in longitudinal and transversal, called as settlement rib and in diagonal direction, named as construction rib. This paper explores the load transfer mechanism along the plate, the ribs, filled soil and the base soil under the footing system. The mechanism is investigated by conducting full scale static load test on SNSF. Strain gauges were installed to monitor the strain increment of each footing elements during loading. 3D numerical analysis was also conducted to verify the experimental results. To analyze the results, Load-Ultimate Ratio Factor (L-URF) was proposed. L-URF was a ratio between ultimate soil bearing capacity of the SNSF and the applied loading at specific element. Higher the L-URF value means higher loading applied at its associate element. Both experimental and numerical results show that at the first stage the loading was fully carried out by the tip of the ribs and transferred to the soil stratum under the footing system. Increasing the loading, the ribs, plate, and filled soil altogether sustain the loading and then transferred to the soil stratum below the footing system. The results also affirm that SNSF generate higher bearing capacity compare with simple shallow footing.  

scholarly journals Load Carrying and Hydrostatic Performances of Innovative Encapsulated Anchorage System for Unbonded Single Strand

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Stress Concentration ◽  
Transfer Test ◽  
Load Transfer ◽  
Maximum Load ◽  
Load Test ◽  
Static Load Test ◽  
Element Analysis ◽  
Bearing Plate ◽  
Anchorage System ◽  
Load Carrying

A new anchorage system is proposed having a circular bearing plate and curvature between the bearing plate and the anchor head to improve stress concentration. A lid with a screw instead of the grouting method is also proposed to prevent moisture penetration. The details of the anchorage device have been chosen to reduce stress concentration based on the finite element analysis. Static load test, load transfer test, and hydrostatic test of fabricated devices were carried out according to ETAG 013 to evaluate the proposed design. As results, the anchorage slip and stabilization satisfied the recommendations of ETAG 013. The maximum load in the load transfer test was at least 1.1 times the ultimate tendon strength. The results of the hydrostatic test showed that the developed anchorage device is watertight to protect against corrosion. As a result of bursting force test, it was confirmed that the proposed anchorage device has more advantages than the conventional rectangular anchorage devices in terms of stress distribution.

scholarly journals Development of Rock Embedded Drilled Shaft Resistance Factors in Korea based on Field Tests

2019 ◽  
Vol 9 (11) ◽  
pp. 2201
Author(s):  
Seok Jung KIM ◽  
Sun Yong KWON ◽  
Jin Tae HAN ◽  
Mintaek YOO
Keyword(s):  
Design Method ◽  
Limit State ◽  
Field Tests ◽  
Load Test ◽  
Drilled Shaft ◽  
Displacement Curve ◽  
Base Resistance ◽  
Resistance Factors ◽  
Shaft Resistance ◽  
The Us

Load and resistance factor design (LRFD) is a limit state design method that has been applied worldwide. Because the data for determining LRFD factors in Korea has been insufficient, the resistance factors suggested by American Association of State Highway and Transportation Officials (AASHTO) in the US have been used for design in Korea; however, these resistance factors were defined based on the characteristics of the predominant bedrock types in the U.S. As such, it remains necessary to determine resistance factors that reflect the bedrock conditions in Korea. Accordingly, in this study, LRFD resistance factors were determined using 13 sets of drilled shaft load test data. To obtain accurate resistance factors, calibration of the elastic modulus of the drilled shaft and the equivalent load–displacement curve considering the axial load and elastic settlement was conducted. After determining accurate resistance values, a reliability analysis was performed. The resistance factors were determined to be within 0.13–0.32 of the AASHTO factors for the shaft resistance, 0.19–0.29 for the base resistance, and 0.28–0.42 for the total resistance. This is equivalent to being 30–60% of the AASHTO-recommended values for the shaft resistance and 40–60% of the AASHTO-recommended values for the base resistance. These differences in resistance factors were entirely the result of discrepancies in the conditions of the rock in the US and Korea in which the shafts were founded.

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