Field Study on the Behavior of Destructive and Non-Destructive Piles Under Compression |
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Authors: | Qian-qing Zhang Shu-Cai Li Li-Ping Li |
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Institution: | 1. Geotechnical and Structural Engineering Research Center , Shandong University , Jinan , China;2. State Key Laboratory for GeoMechanics and Deep Underground Engineering , China University of Mining and Technology , Xuzhou , China zqq5820948@126.com;4. Geotechnical and Structural Engineering Research Center , Shandong University , Jinan , China |
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Abstract: | This paper presents a series of full-scale load tests on long bored piles instrumented with strain gauges along the shafts, including eight field tests of piles loaded to failure and one non-destructive pile load test. The load-displacement response, skin friction, end resistance, and the threshold of the pile-soil relative displacement for fully mobilizing skin resistance were discussed. A simple softening model was proposed to describe the degradation behavior of the skin friction along the pile-soil interface and the load-displacement relationship developed at the pile base. It is found that the shaft resistance degradation investigated in the non-destructive load test only occurs at a shallow depth, and the skin friction of deeper soil is not fully developed. However, unlike the results of the non-destructive load tests, the softening is accompanied by a reduction in skin friction and observed to be along the whole pile depth. The thresholds of pile-soil relative displacement for fully mobilizing skin resistances in different soils have been found to be in the range 0.6% to 2.4% of the pile diameter. Moreover, in practical applications, a bilinear model is assumed to be feasible in analyzing the load-settlement relationship developed at the end of non-destructive pile, whereas the load transmission curve of the soils below the pile base corresponds to a softening model in the field tests of piles loaded to failure. |
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Keywords: | bilinear mode of end resistance load-displacement response pile pile-soil relative displacement softening model of skin friction |
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