Field and Theoretical Analysis on the Response of Destructive Pile Subjected to Tension Load

Abstract

Most field tests are carried out using working piles for verification purposes in China, and loading tests are terminated before achieving true pile capacity. In this work, two full-scale destructive loading tests on tension piles instrumented with strain gauges were conducted to capture true pile capacity. The load-displacement response, load transfer, and threshold of the pile-soil relative displacement for fully mobilizing skin resistance in the uplift case were discussed. It was found that the shaft resistance degradation is observed to be along the pile depth with a reduction factor of 0.905 to 0.931, and the thresholds of pile-soil relative displacement for fully mobilizing skin resistance of the tension pile in different soils are found to be in the range 0.67% to 1.34% of the pile diameter. Based on the field test results, a simple softening model was proposed to describe the degradation behavior of skin friction along the pile-soil interface. Further study was conducted to assess the influence of the threshold of pile-soil relative displacement for fully mobilizing skin friction and the reduction factor on the skin friction. As to the analysis of the response of single pile subjected to tension load, a highly effective iterative computer program was developed using the proposed skin friction softening model. Comparisons of the load-settlement response for the well-instrumented tests were given to demonstrate the effectiveness and accuracy of the proposed simple method.

Analysis on Response of a Single Pile Subjected to Tension Load Using a Softening Model and a Hyperbolic Model

“…In this work, results of the load tests on two instrumented piles presented by the authors (Zhang et al 2013) were chosen to check the reliability of the hyperbolic model and the softening model of skin friction. Full-scale destructive loading tests on the two tension piles instrumented with strain gauges were conducted to capture true pile capacity.…”

“…Observed relationship between s s =s su and S s =S su , and theoretical representation of s s =s su -S s =S su curves for two instrumented piles (modeled afterZhang et al 2013).…”

“…Relationship between unit skin friction and pile-soil relative displacement (modeled afterZhang et al 2013).…”

Experiment on Improving Bearing Capacity of Pile Foundation in Loess Area by Postgrouting

“…e latter includes reinforcement stress gauge and pressure box. Measuring element is an important part of the field test [32,33]. e internal force and deformation of the pile are measured by laying instruments.…”

Development of a New Uplift Pile with Prestressed Semi-Bonded Composite Anchor

“…Krabbenhoft et al [20] performed static load tests of 30 bored cast-in-place uplift piles with different diameters (i.e., 14 and 25 cm) and discussed the factors affecting the pile's uplift bearing capacities, such as pile diameter, grain size of sand, and lateral pressure coefficient of soil. Zhang et al [21] conducted two sets of static load tests on full-scale uplift piles and analyzed the mechanisms of load transfer and ultimate bearing capacity of the piles. In summary, current studies on uplift piles mainly focus on the interpretation of mechanisms of stress and displacement and improving the lateral friction resistance and ultimate bearing capacity [22][23][24].…”