|Table of Contents|

Bearing mechanism of composite foundation with rigid-flexible piles in loess area(PDF)

《交通运输工程学报》[ISSN:1671-1637/CN:61-1369/U]

Issue:
2019年04期
Page:
70-80
Research Field:
道路与铁道工程
Publishing date:

Info

Title:
Bearing mechanism of composite foundation with rigid-flexible piles in loess area
Author(s):
ZHANG En-xiang1;  HE La-ping1;  LONG Zhao1;  HU Zhi-ping2
(1.Gansu CSCEC Municipal Engineering Investigation and Design Institute Co., Ltd., Lanzhou 730000, Gansu, China; 2. School of Civil Engineering, Chang'an University, Xi'an 710061, Shaanxi, China)
Keywords:
airport engineering;  composite foundation with rigid-flexible pile;  field prototype test;  loading transfer mechanism;  collapsible loess;  soil compaction pile
PACS:
U416.1
DOI:
-
Abstract:
In order to investigate the loading transfer mechanism of composite foundation with rigid-flexible piles in collapsible loess area, a field prototype test was conducted. The stress variation rules of piles and soil among piles with different loads and depths were analyzed. Taking the behaviors of rigid single pile as comparison, the characteristic of pile-soil interaction in composite foundation with rigid-flexible piles was summarized. Combined with existing literatures, the difference of mechanical performance between the composite foundation with rigid-flexible piles in collapsible loess area and soft soil area was analyzed. Analysis result indicates that the flexible pile of composite foundation with rigid-flexible piles in collapsible loess area is mainly used to compact the soil among piles and eliminate the collapsibility of soil, and the collapsibility coefficients are basically less than 0.015 after the treatment in the test site. As a result of the compaction of flexible pile, the bearing capacity of soil among piles can be fully developed and the loading transfer ability of rigid pile can be enhanced. The load-sharing ratio of flexible pile is always larger than that of soil among piles in soft soil area. As a result of the high bearing capacity of loess and small modulus ratio between the flexible pile and soil among piles, the load-sharing ratio of soil among piles in collapsible loess area is stable at about 26%, much higher than 7% of flexible piles. The rigid pile in composite foundation pertains to an end bearing friction pile. As the loading increases, the loading transfer ability of rigid pile improves gradually, and the load sharing ratio increases and finally settles at 67%. The improvement of the loading transfer ability of rigid piles is against the development of the bearing capacity of composite foundation with rigid-flexible piles, of which effects on the valid length of pure friction pile should be taken into account in the designing process, and its effects on the bearing capacity of soil at the bottom of the pile of end bearing friction pile should be also been considered.3 tabs, 15 figs, 31 refs.

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Last Update: 2019-09-03