Effects of displacement-softening behavior of concrete-mudstone interface on load transfer of belled bored pile

2021 ◽  
Vol 14 (23) ◽  
Author(s):  
Qijun Hu ◽  
Junsen Zeng ◽  
Leping He ◽  
Yutong Fu ◽  
Qijie Cai
Keyword(s):  
Load Transfer ◽  
Softening Behavior ◽  
Bored Pile

scholarly journals Load transfer on instrumented prestressed ground anchors in sandy soil

2021 ◽  
Vol 14 (6) ◽  
Author(s):  
Alex Micael Dantas de Sousa ◽  
Yuri Daniel Jatobá Costa ◽  
Luiz Augusto da Silva Florêncio ◽  
Carina Maria Lins Costa
Keyword(s):  
Skin Friction ◽  
Sandy Soil ◽  
Load Transfer ◽  
Retaining Wall ◽  
Load Variations ◽  
Bored Pile ◽  
Ground Anchors ◽  
Anchor Testing ◽  
Wall System ◽  
Unbonded Length

abstract: This study evaluates load variations in instrumented prestressed ground anchors installed in a bored pile retaining wall system in sandy soil. Data were collected from instrumentation assembled in the bonded length of three anchors, which were monitored during pullout tests and during different construction phases of the retaining wall system. Instrumentation consisted of electrical resistance strain gauges positioned in five different sections along the bonded length. Skin friction distributions were obtained from the field load measurements. Results showed that the skin friction followed a non-uniform distribution along the anchor bonded length. The mobilized skin friction concentrated more intensely on the bonded length half closest to the unbonded length, while the other half of the bonded length developed very small skin friction. The contribution of the unbonded length skin friction to the overall anchor capacity was significant and this should be accounted for in the interpretation of routine anchor testing results. Displacements applied to the anchor head were sufficient to mobilize the ultimate skin friction on the unbonded length, but not on the bonded length. Performance of loading-unloading stages on the ground anchor intensified the transfer of load from the unbonded length to the bonded length. Long-term monitoring of the anchor after lock-off revealed that the load at the anchor bonded length followed a tendency to reduce with time and was not significantly influenced by the retaining wall construction phases.

Expansive concrete drilled shafts

1985 ◽  
Vol 12 (2) ◽  
pp. 382-395 ◽  
Author(s):  
Shamim A. Sheikh ◽  
Michael W. O'Neill ◽  
M. A. Mehrazarin
Keyword(s):  
Load Transfer ◽  
Stress Path ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Cement Concrete ◽  
Bored Pile ◽  
Expansive Concrete ◽  
Stiff Clay ◽  
Expansive Cement

A hypothesis is presented in this paper that states that expansive cement concrete produces a stronger bond between the concrete in a drilled shaft (bored pile) and the surrounding soil than does normal cement; this results in an increase in the frictional component of capacity and a reduction in the settlement of the shaft at working load levels.Four types of expansive cement, type "K" cement (the expansive cement available commercially) and three made from commercially available materials, were tested for their expansion characteristics; two of them were selected to be used in two instrumented drilled shafts in stiff clay. Normal (type 1) cement was used in a third shaft to serve as a reference. The three shafts were tested to failure after essentially all the expansion was deemed to have taken place in the two expansive concrete shafts. Lateral and longitudinal expansion of the shafts were monitored during the curing period. Load–settlement behaviour and load transfer between shafts and soil during the tests were studied.The test results permitted the preliminary conclusion that expansive cement concrete can increase the frictional capacity of drilled shafts in stiff clay by as much as 50% and reduce the settlement by about 50%. The results are valid for short-term behaviour of drilled shafts made of expansive cement. The long-term behaviour of such shafts remains to be studied. Key words: base bearing capacity, bored pile, cement (expansive), concrete (structural), drilled shaft, ettringite, expansion, frictional capacity, settlement, stress path.

Tension tests on bored piles in cemented desert sands

1994 ◽  
Vol 31 (4) ◽  
pp. 597-603 ◽  
Author(s):  
Nabil F. Ismael ◽  
Hasan A. Al-Sanad ◽  
Fahad Al-Otaibi
Keyword(s):  
Load Transfer ◽  
Field Tests ◽  
Standard Penetration Test ◽  
Uplift Capacity ◽  
Calcareous Sand ◽  
Shaft Resistance ◽  
Bored Pile ◽  
Bored Piles ◽  
Cemented Sands ◽  
Strength Characterization

The load transfer of bored piles in medium dense cemented sands was examined by field tests at two sites. At the first site, two bored piles were tested in axial tension to failure. One pile was instrumented with strain guages to measure the axial load distribution at all load increments. The results indicate significant load transfer along the pile length. The average shaft resistance measured was 80 and 100 kN/m2 in medium-dense and very dense, weakly cemented calcareous sand, respectively. At the second site, a tension test was carried out on a bored pile in uncemented cohesionless sand. By comparing the results at the two sites the influence of cementation on the uplift capacity was assessed. The shaft resistance depends on many factors including the relative density, degree of cementation, soil fabric, and method of construction. It increases with the standard penetration test (SPT) N values; however, the SPT is not considered a reliable test for strength characterization of cemented sands. Analysis of the pile capacity can be made considering both components of soil strength, namely, cohesion intercept c and angle of shearing resistance [Formula: see text]. Key words : bored piles, cemented sands, uplift capacity, friction, shaft resistance.

Effect of Temperature on Strain Softening Behavior of Composites with Small Misaligned Whiskers

2007 ◽  
Vol 353-358 ◽  
pp. 1287-1289
Author(s):  
Ai Bin Li ◽  
Qing Yuan Meng ◽  
Lin Geng ◽  
Guo Jian Cao ◽  
Wen Bin You ◽  
...  
Keyword(s):  
Load Transfer ◽  
Strain Softening ◽  
Effect Of Temperature ◽  
Softening Behavior ◽  
Composite Deformation ◽  
Compression Strain ◽  
The Matrix ◽  
Work Hardening Rate ◽  
Matrix Flow ◽  
Increasing Temperature

The effect of temperature on strain softening behavior of composites with small misaligned whiskers is investigated. The results show that the temperature affects the matrix and whisker mechanical behavior and corresponding composite deformation behavior. With increasing temperature, the whisker rotation angle increases, but their breakage decreases. Meanwhile elevating temperature not only reduces the matrix flow stress and work hardening rate, but also decreases load transfer from the matrix to the whiskers and stress induced by the whisker rotation and breakage.It is found that during hot compression, strain softening behavior of composites decreases as temperature increases.

scholarly journals Tahanan Gesekan Selimut pada Tiang Bor Panjang

2019 ◽  
Vol 10 (2) ◽  
pp. 185-207
Author(s):  
Andrias Suhendra Nugraha
Keyword(s):  
Skin Friction ◽  
Load Transfer ◽  
Friction Resistance ◽  
Bored Pile ◽  
Pile Diameter

Penelitian ini bertujuan untuk mempelajari mekanisme transfer beban (load transfer) dan tahanangesekan selimut (skin friction resistance) dari hasil uji beban aksial terinstrumentasi pada tiang bor(bored pile). Diameter tiang, d, yang ditinjau pada penelitian ini adalah 1.00 m dan panjang tiang,L, yang ditinjau adalah 43.10m dan 48.00m. Hasil uji beban aksial terinstrumentasi pada 2 tiangbor panjang (long bored pile) dengan ujung bawah tiang terletak pada tanah lanau (silt) danlempung (clay) dengan konsistensi very stiff hingga hard menunjukkan bahwa tahanan gesekanselimut termobilisasi pada deformasi yang kecil yaitu pada 0.9% d hingga 2.6% d.

scholarly journals Load Transfer On Bored Pile Foundation Instrumented With Fiber Optic And Concrete Quality Analysis

UKaRsT ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 204
Author(s):  
Kevin Martandi Setianto ◽  
Cecilia Lauw Giok Swan ◽  
Paulus Pramono Rahardjo
Keyword(s):  
Pile Foundation ◽  
Load Transfer ◽  
Fiber Optic ◽  
Measurement Data ◽  
Quality Analysis ◽  
Loading Test ◽  
Bored Pile ◽  
Concrete Quality ◽  
Strain Data ◽  
Manual Calculation

The problem in the construction method of the bored pile is the contamination of mud or the other contaminant that can cause the modulus of elasticity of concrete to decrease. This research determines the modulus of concrete on a bored pile foundation instrumented with fiber-optic (FO) with a manual calculation based on strain data during loading test, validated with the results of research in the laboratory and numerical analysis. Fiber optic was used to measure the strain along with the pile during the loading test. The bored pile foundation is divided into 12 segments with the same strain characteristics, and then the modulus value is calculated. The result is the modulus value of each segment is different, and the value of the modulus changes along with the increase in strain; the modulus will decrease as the strain increases. This differs from the theory that the modulus has a fixed value approximated by empirical equations. Made a cylindrical concrete sample on both sides, which installed a FO to record the strain during the loading test. The result is true that the modulus is not constant but decreases as the strain increases. It is shown in the result of analysis to fiber-optic measurement data. Created a model in Plaxis2D for validation, and the results are not much different from the manual calculation.

Experimental Study on O-Cell Test of Long Rock Socket Bored Pile

2013 ◽  
Vol 477-478 ◽  
pp. 509-513
Author(s):  
Li Zhang Yao ◽  
Deng Feng Sang ◽  
Lin Wang Su ◽  
De Yin Tan
Keyword(s):  
Load Transfer ◽  
Test Method ◽  
Load Testing ◽  
Offshore Structure ◽  
Test Device ◽  
Test Technique ◽  
Bored Pile ◽  
Cell Test ◽  
Bearing Behavior ◽  
Shaft Friction

The O-cell test method which was applied on the pile load testing was introduced, including the basic principle, test device and test technique. Based on the project of offshore structure in Malaysia, the O-cell test was performed on the long rock socket bored pile. The bearing behavior and load transfer characteristics were analyzed. The shaft friction in the rock played an important role in the pile shaft friction. In some long rock socket pile, The O-cell method cant test the ultimate capacity of some long rock socket pile.

INSTRUMENTED PILE LOAD TESTING WITH DISTRIBUTED OPTICAL FIBRE STRAIN SENSOR

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Hisham Mohamad ◽  
Bun Pin Tee
Keyword(s):  
Load Transfer ◽  
Strain Sensor ◽  
Time Domain Analysis ◽  
Load Test ◽  
Load Testing ◽  
Fibre Optic ◽  
Strain Sensing ◽  
Residual Soils ◽  
Bored Pile ◽  
Test Pile

An instrumented pile load test was conducted for a 1.2m diameter bored pile at Putrajaya to verify pile performance towards geotechnical design. This test pile was instrumented with new monitoring technique using distributed strain sensing known as Brillouin Optical Time Domain Analysis (BOTDA) and compared with conventional sensors, i.e. vibrating wire strain gauge, LVDT (linear variable differential transformer) and dial gauge. This manuscript includes the description of subsurface conditions consisting of weathered granitic residual soils, test pile installation and instrumentation setup of Maintain Load Test (MLT). Field measurement results such as the load transfer response and average unit shaft resistance using the distributed fibre optic strain sensor were well matched with the results using the conventional sensors. However, the distributed fibre optic strain sensor has the added advantage of detecting the localized defect such as pile necking, bending, and overall behaviour of bored pile effectively. 

Load tests on full-scale bored pile groups

2012 ◽  
Vol 49 (11) ◽  
pp. 1293-1308 ◽  
Author(s):  
Guoliang Dai ◽  
Rodrigo Salgado ◽  
Weiming Gong ◽  
Yanbei Zhang
Keyword(s):  
Load Transfer ◽  
Pile Group ◽  
Interaction Coefficient ◽  
Full Scale ◽  
Pile Groups ◽  
Interaction Coefficients ◽  
Bored Pile ◽  
Load Response ◽  
Load Tests ◽  
Single Piles

The interactions between closely spaced piles in a pile group are complex. Very limited experimental data are available on the loading of full-scale bored pile groups. This paper reports the results of axial static load tests of both full-scale instrumented pile groups and single piles. The load tests aimed to ascertain the influence of number, length, and spacing of the piles on pile group load response. Experiments varied in the number of piles in the group, pile spacing, type of pile groups, and pile length. All piles had a diameter of 400 mm. Two-, four-, and nine-pile groups with pile lengths of 20 and 24 m were tested. As the isolated piles and some piles in the pile groups were instrumented, the load transfer and load–settlement curves of both piles in isolation and individual instrumented piles in the groups were obtained. The interaction coefficient for each pile in the group was back-calculated from the measured data. The interaction coefficients are shown to be dependent on pile proximity, as usually assumed in elastic analyses, but also on settlement and on the size of the group.

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