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.

Long-term behavior of expansive concrete drilled shafts

1986 ◽  
Vol 13 (2) ◽  
pp. 213-217 ◽  
Author(s):  
Shamim A. Sheikh ◽  
Michael W. O'Neill
Keyword(s):  
Visual Observation ◽  
Drilled Shafts ◽  
Compression Tests ◽  
Normal Concrete ◽  
Bored Pile ◽  
Expansive Concrete ◽  
Side Resistance ◽  
Strength And Stiffness ◽  
Long Term Behavior

The research reported here is a continuation of work reported earlier in which it was concluded that the use of expansive cement concrete increased the side resistance of drilled shafts (bored piles) in stiff clay by as much as 50% over that in normal concrete shafts and reduced the settlement by about 50%. The conclusions were based on tests conducted at a concrete age of about 2 months. A year and a half later, the three shafts (one made with normal concrete and two made with expansive concrete) were tested again and the same comparatively better behavior of expansive concrete shafts was observed. The base capacities of all the shafts increased over this period owing to the consolidation of soil caused by residual base stresses following the initial tests. The shafts were later extracted for visual observation and coring. The compression tests on concrete cores obtained from various depths along the shafts indicated that expansive concrete behaves as a sound structural material in the long term. The gains in strength and stiffness of expansive concrete over normal concrete over a period of 2 years were found to be significant. Key words: base bearing capacity, bored pile, cement (expansive), concrete (structural), drilled shaft, expansion, frictional capacity, long-term behavior, settlement.

Field P–y curves in weathered rock

2007 ◽  
Vol 44 (7) ◽  
pp. 753-764 ◽  
Author(s):  
Kook Hwan Cho ◽  
Mohammed A Gabr ◽  
Shane Clark ◽  
Roy H Borden
Keyword(s):  
Field Tests ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Weak Rock ◽  
Strain Gages ◽  
Weathered Rock ◽  
Clay Model ◽  
Rock Model ◽  
Stiff Clay ◽  
Subgrade Modulus

In weathered and decomposed rock profiles, the lack of an acceptable analysis procedure for estimating lateral load–displacement response of drilled shafts is compounded by the unavailability of weathered material properties, including the material's lateral subgrade reaction modulus. Such deficiency often leads to the overdesign of the drilled shaft foundation. Six field tests were conducted on drilled shafts to investigate the shape and magnitude of P–y curves in weathered rock material at three locations in North Carolina. The tested shafts were instrumented using dial gages, strain gages, and continuous vertical inclinometers. The measured load versus deflection data are used to study the stiffness response of weathered rock. Measured lateral responses are compared with the results estimated based on a "weak rock" model and a stiff clay model. The comparison shows that Reese's weak rock model overestimated the resistances of the tested shafts while the stiff clay model consistently underestimated the measured shaft resistances. The measured and computed results are analyzed and discussed.Key words: drilled shaft, weathered rock P–y curve, subgrade modulus, ultimate resistances in weathered rock, verification tests.

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.

Monitoring a Drilled Shaft Retaining Wall in Expansive Clay: Long-Term Performance in Response to Moisture Fluctuations

IFCEE 2015 ◽  
2015 ◽  
Author(s):  
Andrew C. Brown ◽  
Gregory Dellinger ◽  
Ali Helwa ◽  
Chadi El-Mohtar ◽  
Jorge Zornberg ◽  
...  
Keyword(s):  
Retaining Wall ◽  
Drilled Shaft ◽  
Expansive Clay ◽  
Long Term Performance ◽  
Term Performance

Long-Term Performance of Recycled Portland Cement Concrete Pavement

1996 ◽  
Vol 1525 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Stephen A. Cross ◽  
Mohamed Nagib Abou-Zeid ◽  
John B. Wojakowski ◽  
Glenn A. Fager
Keyword(s):  
Portland Cement ◽  
Test Section ◽  
Load Transfer ◽  
Construction Materials ◽  
Concrete Pavement ◽  
Recycled Concrete ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Cement Concrete Pavement ◽  
Portland Cement Concrete Pavement

Over the past years there has been an increasing interest in recycling construction materials, particularly hot-mix asphalt (HMA) and portland cement concrete pavements (PCCP). To this end the Kansas Department of Transportation (KDOT) participated in Demonstration Project 47, Recycling Portland Cement Concrete Pavement, by recycling a moderately D-cracked concrete pavement and monitoring the performance over a 10-year period. The recycled concrete pavement (RCP) aggregate was evaluated in four test sections consisting of two control sections, one test section of portland cement-treated base (CTB) with RCP aggregate, and one test section using RCP aggregate in the PCCP and CTB. An HMA shoulder using RCP as coarse aggregate was also constructed. The test sections were monitored over a 10-year period for performance including faulting, roughness, load transfer, and friction measurements. Faulting, roughness, performance level, and joint distress measurements from KDOT's 1995 pavement condition survey were used to compare the performance of the recycled sections with PCCP of similar age and traffic in the same area of the state. All test sections performed well, with the CTB and PCCP sections with RCP aggregates showing slightly more distress.

scholarly journals Proposed point bearing load transfer function in jointed rock-socketed drilled shafts

2013 ◽  
Vol 53 (4) ◽  
pp. 596-606 ◽  
Author(s):  
Jaehwan Lee ◽  
Kwangho You ◽  
Sangseom Jeong ◽  
Jaeyoung Kim
Keyword(s):  
Transfer Function ◽  
Load Transfer ◽  
Jointed Rock ◽  
Drilled Shafts ◽  
Bearing Load ◽  
Load Transfer Function

Long term studies on the utilisation of quartz sandstone wastes in cement concrete

2017 ◽  
Vol 143 ◽  
pp. 634-642 ◽  
Author(s):  
Sanjeev Kumar ◽  
Ramesh Chandra Gupta ◽  
Sandeep Shrivastava
Keyword(s):  
Cement Concrete ◽  
Long Term Studies

Comparison Between DEXA and Finite Element Studies in the Long-Term Bone Remodeling of an Anatomical Femoral Stem

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
A. Herrera ◽  
J. J. Panisello ◽  
E. Ibarz ◽  
J. Cegoñino ◽  
J. A. Puértolas ◽  
...  
Keyword(s):  
Finite Element ◽  
Bone Density ◽  
Bone Mass ◽  
Simulation Model ◽  
Load Transfer ◽  
Fe Simulation ◽  
Femoral Stem ◽  
Mineral Density ◽  
Biomechanical Behavior

The implantation of a cemented or cementless femoral stem changes the physiological load transfer on the femur producing an effect on the bone called adaptative remodeling. The patterns of this remodeling are attributed to mechanical and biological factors, and those changes in bone mineral density have been determined in long-term densitometry studies. This technique has proved to be a useful tool able to quantify small changes in bone density in different femoral areas, and it is considered to be ideal for long-term studies. On the other hand, the finite element (FE) simulation allows the study of the biomechanical changes produced in the femur after the implantation of a femoral stem. The aim of this study was to contrast the findings obtained from a 5 year follow-up densitometry study that used a newly designed femoral stem (73 patients were included in this study), with the results obtained using a finite element simulation that reproduces the pattern of load transfer that this stem causes on the femur. In this study we have obtained a good comparison between the results of stress of FE simulation and the bone mass values of the densitometry study establishing a ratio between the increases in stress (%) versus the increases in bone density (%). Hence, the changes in bone density in the long term, compared with the healthy femur, are due to different load transfers after stem implantation. It has been checked that in the Gruen zone 7 at 5 years, the most important reduction in stress (7.85%) is produced, which coincides with the highest loss of bone mass (23.89%). Furthermore, the simulation model can be used with different stems with several load conditions and at different time periods to carry out the study of biomechanical behavior in the interaction between the stem and the femur, explaining the evolution of bone density in accordance to Wolff’s law, which validates the simulation model.

Sign in / Sign up

Export Citation Format

Share Document