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.

scholarly journals Data-Driven Field Observational Method of a Contiguous Bored Pile Wall System Affected by Accidental Groundwater Drawdown

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 268
Author(s):  
Elizabeth Eu-Mee Chong ◽  
Dominic Ek-Leong Ong
Keyword(s):  
Cement Grout ◽  
Data Driven ◽  
Observational Method ◽  
Deep Excavation ◽  
Corner Effect ◽  
Bored Pile ◽  
Ground Anchors ◽  
Groundwater Drawdown ◽  
Tunnel Section ◽  
Wall System

This paper presents the use of a 700 mm-diameter contiguous bored pile (CBP) wall for a main basement deep excavation project with cut-and-cover tunnel. Due to the presence of cement grout columns between piles behind the CBP wall, the main basement was considered to be ‘impermeable’. However, site observations have shown that installation of ground anchors have unintentionally punctured the water tightness of the wall, creating leakages through the CBP wall and the possibility of localized groundwater lowering, as evidenced by the relatively large settlements. In the absence of cement grout columns at the cut-and-cover tunnel section, immediate groundwater drawdown was observed with the excavation rate. Settlement induced by the excavation and groundwater drawdown only slowed down upon the casting of skinwall to prevent groundwater from flowing through the wall. The accidental groundwater leakage led to small wall deflection. The ratio of maximum settlement to maximum deflection is atypical to those reported in the literature. The analysis also revealed that corner effect is significant with smaller settlement registered at the corners of the wall.

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.

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.

Appraisal of reliable skin friction variation in a bored pile

2015 ◽  
Vol 168 (1) ◽  
pp. 75-86 ◽  
Author(s):  
Ramli Nazir ◽  
Hossein Moayedi ◽  
Mansour Mosallanezhad ◽  
Alireza Tourtiz
Keyword(s):  
Skin Friction ◽  
Bored Pile

Behavior of Tire-Geogrid–Reinforced Retaining Wall System under Dynamic Vehicle Load

2020 ◽  
Vol 20 (4) ◽  
pp. 04020017 ◽  
Author(s):  
Lihua Li ◽  
Junchao Yang ◽  
Henglin Xiao ◽  
Lei Zhang ◽  
Zhi Hu ◽  
...  
Keyword(s):  
Retaining Wall ◽  
Vehicle Load ◽  
Reinforced Retaining Wall ◽  
Wall System

The Application Research and Discussion on a Viaduct Artificial Excavated Pile Technology

2012 ◽  
Vol 446-449 ◽  
pp. 2449-2452
Author(s):  
Dong Guo Li ◽  
Gui Mei Shi
Keyword(s):  
Bearing Capacity ◽  
Pile Foundation ◽  
Retaining Wall ◽  
Wall Effect ◽  
Construction Technology ◽  
Application Research ◽  
Technical Work ◽  
Bored Pile

A viaduct of the Qinglai expressway fourth contract was artificial excavated piles. The construction technical work was regarded as an example. The technical comparison were done between the artificial excavated pile and the bored pile on the pile foundation bearing capacity and the retaining wall effect . The artificial excavated pile replacing the bored pile was feasible, and the construction technology and the key problems of the artificial excavated piles were confirmed. The references were provided to the similar projects.

A Destructive Field Study on the Behavior of Pile under Ten

2010 ◽  
Vol 163-167 ◽  
pp. 4524-4528
Author(s):  
Shi Min Zhang ◽  
Gang Wei
Keyword(s):  
Skin Friction ◽  
Load Test ◽  
Silty Sand ◽  
Silty Clay ◽  
Test Results ◽  
Bored Pile ◽  
Tip Resistance ◽  
Stress States ◽  
Sand And Gravel ◽  
Different Soils

This paper involves a destructive full-scale load test on long bored pile instrumented with strain gauges along the shaft. The load-displacement response, the distribution of axial force, and the thresholds of displacement for fully mobilizing the skin resistances in different soils in tension case were discussed in this paper. The field test results show that the measured tip resistance in the pile under tension is near zero during the whole loading, and the softening is accompanied with a reduction in skin friction when the skin friction is fully developed. It also can be investigated that the threshold of displacement for fully mobilizing skin friction is different even if in the same soil type due to different soil stress states. Generally speaking, the thresholds of relative pile-soil displacement for fully mobilizing skin frictions in the sandy silt, silty sand mixed silt, silty clay, silty clay mixed sand and gravel are about 4 mm, 11 mm, 7 mm, 6 mm, and 5.5 mm, respectively.

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