Pile load tests in saline permafrost at Clyde River, Northwest Territories

1988 ◽  
Vol 25 (1) ◽  
pp. 24-32 ◽  
Author(s):  
J. F. (Derick) Nixon
Keyword(s):  
Bearing Capacity ◽  
Pore Water ◽  
Salt Content ◽  
Field Testing ◽  
Testing Procedure ◽  
Load Testing ◽  
Pile Design ◽  
Load Tests ◽  
Pore Water Salinity ◽  
Pile Load Tests

Significant salt content in the pore phase of permafrost causes dramatic reduction in strength or bearing capacity. Previous experience with laboratory tests and limited field testing discussed in the Soviet literature indicate that creep rates can be accelerated many times and foundation bearing capacities reduced by factors of 2–3 if pore water salinities exceed 10–20 ppt. At Clyde River on the northwest coast of Baffin Island, pile load tests were carried out in 1982. A combination of high salinities and significant excess ice contents at some locations suggested that a limited program of pile load testing should be carried out to confirm or modify the initial pile loadings based on previously published material. No fully documented case history was available to support initial pile design loads.Three piles were subjected to loads of five different magnitudes for different durations. Creep settlement was initiated and persisted in all cases. Continuous curve fitting was carried out by computer, and the resulting smoothed strain rate plotted with time. The minimum settlement rates were compared with earlier predictions. They were generally somewhat faster than results from previous laboratory saline creep testing combined with theoretical pile design based on creep settlement.The tests highlight the dramatic reductions in foundation bearing capacity and acceleration in pile creep rates that can be expected in permafrost exhibiting significant pore water salinity. A simplified testing procedure suitable for laboratory or field testing is described. Key words: permafrost, saline, piles, load tests, laboratory, field, in situ, capacity, creep, creep rate, salinity test.

Predicting the Ultimate Bearing Capacity of Single Piles Based on CPTU

2011 ◽  
Vol 243-249 ◽  
pp. 4402-4407
Author(s):  
Yong Hong Miao ◽  
Guo Jun Cai ◽  
Song Yu Liu
Keyword(s):  
Load Test ◽  
Load Testing ◽  
Pile Capacity ◽  
Piezocone Penetration Test ◽  
Load Carrying ◽  
Load Tests ◽  
Pile Load Test ◽  
Single Piles ◽  
Pile Load Tests ◽  
Best Fit

Six methods to determine axial pile capacity directly based on piezocone penetration test (CPTU) data are presented and evaluated. Analyses and evaluation were conducted on three types piles that were failed during pile load testing. The CPT methods, as well as the CPTU methods, were used to estimate the load carrying capacities of the investigated piles (Qp ). Pile load test were used to determine the measured load carrying capacities (Qm). The pile capacities determined using the different methods were compared with the measured pile capacities obtained from the pile load tests. Two criteria were selected as bases of evaluation: the best fit line for Qp versus Qm and the arithmetic mean and standard deviation for the ratio Qp /Qm. Results of the analyses showed that the best methods for determining pile capacity are the CPTU methods.

scholarly journals Bi-Directional Static Load Tests of Pile Models

2020 ◽  
Vol 10 (16) ◽  
pp. 5492
Author(s):  
Michał Baca ◽  
Włodzimierz Brząkała ◽  
Jarosław Rybak
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Load Testing ◽  
Pile Capacity ◽  
Pile Shaft ◽  
Load Tests ◽  
S Curve ◽  
Definition Of ◽  
Standard Tests ◽  
Static Load Testing

This work examined a new method of bi-directional static load testing for piles, referencing the Osterberg test. Measurements were taken, on a laboratory scale, using six models of piles driven into a box filled with sand. This method allowed for separate measurements of pile base and pile shaft bearing capacities. Based on the results, the total pile bearing capacity and equivalent Q–s diagrams were estimated. The results obtained show that the structure of the equivalent curve according to Osterberg is a good approximation of the standard Q–s curve obtained from load tests, except for loads close to the limit of bearing capacity (those estimates are also complicated by the inapplicability and ambiguity of a definition of the notion of limit bearing capacity); the equivalent pile capacity in the Osterberg method represents, on average, about 80% of the capacity from standard tests.

scholarly journals Influence of time on the bearing capacity of precast piles

2013 ◽  
Vol 35 (4) ◽  
pp. 65-74 ◽  
Author(s):  
Kazimierz Gwizdała ◽  
Paweł Więcławski
Keyword(s):  
Bearing Capacity ◽  
Cohesive Soils ◽  
Geotechnical Parameters ◽  
Well Control ◽  
Time Points ◽  
Pile Shaft ◽  
Field Investigations ◽  
Load Tests ◽  
Pile Load Tests ◽  
Change Of Microstructure

Abstract One of the most popular types of foundations in layered subsoil with very differentiated soil shear strengths are precast piles. One of the reasons is the fact that we can well control the driving process during the installation of these piles. The principles of the assessment of bearing capacity and settlements of the piles given by Eurocode 7, concentrate on two main methods, i.e., Static Pile Load Tests (SPLT) and Dynamic Driving Analysis (PDA). However, the evaluation of real load-settlement curve for piles being driven in layered subsoil, where noncohesive and cohesive soils occur alternately, is neither easy nor straightforward. In the paper, the results of both SPLT and PDA tests for objects on the highways in Poland are presented. Field investigations carried out at various time points since the installation of piles (from 7 to 90 days) revealed an increase of bearing capacity with time. The reason for this may be a change of the soil state near the piles due to their driving (displacement of piles) as well as a change of microstructure at the contact between soil and pile shaft. The results of load tests were referred to the geotechnical parameters of the subsoil, which was recognized by means of traditional borings and CPTU tests. The results of tests allow phenomena occurring with time to be assessed and bearing capacity of precast piles to be predicted.

Field pile load tests in saline permafrost. I. Test procedures and results

1993 ◽  
Vol 30 (1) ◽  
pp. 34-45 ◽  
Author(s):  
K. W. Biggar ◽  
D. C. Sego
Keyword(s):  
Companion Paper ◽  
Load Test ◽  
Load Testing ◽  
Test Procedures ◽  
Testing Procedures ◽  
Uplift Load ◽  
Load Tests ◽  
Pile Load Test ◽  
Pile Load Tests

A pile load test program carried out in Iqaluit, Northwest Territories, to provide design information for the Short Range Radar sites is described. The program consisted of testing 10 steel pipe piles with various surface modifications backfilled with clean sand and 4 Dywidag bars backfilled with Ciment Fondu™ grout. All tests were performed in saline permafrost. This paper describes the site conditions, installation procedures and pile uplift load testing procedures, and results of the pile load tests. The beneficial effect of modifications to the pile surface and backfill material is identified. The analysis and discussions of the results are presented in a companion paper. Key words : permafrost, saline, piles, load tests, field, in situ, capacity.

scholarly journals Bearing capacity assessment of bored piles equipped with expander body systems using the mechanics of unsaturated soils

2021 ◽  
Vol 337 ◽  
pp. 03011
Author(s):  
Fernando Feitosa Monteiro ◽  
Renato Pinto da Cunha ◽  
Marcos Fábio Porto de Aguiar ◽  
Carlos Medeiros Silva
Keyword(s):  
Bearing Capacity ◽  
Unsaturated Soils ◽  
Federal District ◽  
Matric Suction ◽  
Engineering Practice ◽  
Foundation Engineering ◽  
Load Tests ◽  
Single Piles ◽  
Bored Piles ◽  
Pile Load Tests

Bearing capacity of single piles are occasionally predicted using the renowned theoretical methods (α and β methods). These methods are based on laboratory tests, which can be time-consuming, but also applicable in foundation engineering practice for unsaturated soils. Full-scale pile load tests were carried out on bored piles equipped with Expander Body Systems in the Federal District of Brazil, known for its unsaturated, collapsible and porous soil. This paper has the aim to assess the applicability of the β method, considering the contribution of soil matric suction, in order to estimate the bearing capacity of these piles subjected to uplift and compression loads in unsaturated soils. Based on the experimental results, it is indicated that the use of the β method considering the matric suction, can be a useful tool for bearing capacity estimation of bored piles equipped with Expander Body Systems in unsaturated soils.

Axial compressive capacity of driven piles in sand: a method including post-driving residual stresses

2001 ◽  
Vol 38 (2) ◽  
pp. 364-377
Author(s):  
Ahmed Shlash Alawneh ◽  
Osama Nusier ◽  
Abdullah I Husein Malkawi ◽  
Mustafa Al-Kateeb
Keyword(s):  
Residual Stresses ◽  
Bearing Capacity ◽  
Relative Density ◽  
Friction Angle ◽  
Accurate Estimate ◽  
Driven Piles ◽  
Pile Capacity ◽  
Shaft Resistance ◽  
Load Tests ◽  
Pile Load Tests

In this paper, empirical formulae were developed between the well-known pile bearing capacity factors (Nq and β) and parameters which include friction angle of sand, relative density, average effective vertical stress, and deformability of the soil below the pile toe. The developed empirical formulae were totally based on a database comprised of 28 well-documented compressive pile load tests collected exclusively from geotechnical literature. The actual measurements of shaft and end-bearing resistances of each pile in the database were adjusted to account for post-driving residual loads. Calculation of pile bearing capacity factors (Nq and β) was based on the adjusted shaft and end-bearing resistances rather than the actual unadjusted measured resistances for residual loads. Comparison of predicted and measured compressive capacity of an independent database comprised of 18 pile load tests showed that the developed formulae yield a reasonably accurate estimate of compressive pile capacity in cohesionless soils.Key words: driven piles, residual load, toe resistance, shaft resistance.

scholarly journals Stop Criteria for Proof Load Tests Verified with Field and Laboratory Testing of the Ruytenschildt Bridge

2018 ◽  
Author(s):  
Eva O.L. Lantsoght ◽  
Yuguang Yang ◽  
Ane de Boer
Keyword(s):  
Laboratory Testing ◽  
Laboratory Tests ◽  
Structural Response ◽  
Bending Moment ◽  
Field Testing ◽  
Load Test ◽  
Load Testing ◽  
Load Tests ◽  
Small Change ◽  
Plain Bars

As the existing bridge stock is aging, improved assessment methods such as proof load testing become increasingly important. Proof load testing involves large loads, and as such the risk for the structure and personnel can be significant. To capture the structural response, extensive measurements are applied to proof load tests. Stop criteria, based on the measured quantities, are used to identify when further loading in a proof load test is not permitted. For proof load testing of buildings, stop criteria are available in existing codes. For bridges, recently stop criteria based on laboratory tests on beams reinforced with plain bars have been proposed. Subsequently, improved stop criteria were developed based on theoretical considerations for bending moment and shear. The stop criteria from the codes and the proposed stop criteria are compared to the results from field testing to collapse on the Ruytenschildt Bridge, and to the results from laboratory tests on beams sawn from the Ruytenschildt Bridge. This comparison shows that only a small change to the stop criteria derived from laboratory testing is necessary. The experimental evidence strengthens the recommendation for using the proposed stop criteria in proof load tests on bridges for bending moment, whereas further testing to confirm the stop criteria for shear is necessary.

scholarly journals Accuracy of pile capacity assessment on the basis of piling reports

2019 ◽  
Vol 97 ◽  
pp. 04029 ◽  
Author(s):  
Jakub Rainer
Keyword(s):  
Bearing Capacity ◽  
Operational Reliability ◽  
Driven Piles ◽  
Safety Factors ◽  
Pile Capacity ◽  
Current Assessment ◽  
Proper Design ◽  
Foundation Pile ◽  
Load Tests ◽  
Pile Load Tests

Current assessment of foundation pile bearing capacity during driving may considerably improve operational reliability in terms of loads to be transferred. It also enables proper design and trial examinations by focusing attention on piles with atypical driving characteristics. The paper presents the method applicable to assess the bearing capacity of prefabricated driven piles and provides analysis of likelihood of this assessment by the example of numerous prefabricated piles documented by piling reports and results of static pile load tests to the extent allowing to determining the limit bearing capacity. The results attained could be the basis to determine respective safety factors in pile design based on driving resistance analysis.

scholarly journals Application of the ‘CPT 2012’ model of AFNOR standard for column design in Poland – Jazowa case study

2019 ◽  
Vol 262 ◽  
pp. 04001
Author(s):  
Lech Bałachowski ◽  
Jakub Konkol ◽  
Kamila Międlarz
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Eurocode 7 ◽  
Pile Design ◽  
Load Tests ◽  
Column Design ◽  
French Standard

This paper presents the ‘CPT 2012’ model incorporated into the AFNOR NF P94-262:2012-07, French standard for pile design fully compatible with Eurocode 7, to the wider Polish audience. The bearing capacity of three reference columns for Vistula Marshlands have been calculated according to ‘CPT 2012’ model and AFNOR recommendations. Then, the design resistances have been compared with ultimate column bearing capacity measured during static load tests conducted on reference columns. The results of comparison are discussed and the discrepancies between measured and calculated bearing capacities are shortly commented.

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