Combined with the project of mobile communication comprehensive building

Gansu Dingxi branch

China mobile in Dingxi new city

a lasting pile immersion test was made in the site of collapsible loess with large thickness; while the changing characteristics of pile negative friction and settlement process of soil were analyzed for different depths and limits (the diameter and length of test pile were 800 mm and 26 m respectively with 2 m pit in depth). The test results show that under the special immersion condition mentioned above

there appear multiple peak values along the pile

and positive and negative frictions presented staggered distribution phenomenon; so that the value of average negative friction couldn’t be given by Technical code for building pile foundation[1]; then with multimodal distribution of soil settlement amount

its changing tendency directly affects its trend in positive and negative friction along the pile; also

in the neutral point location

the single reference value provided by Technical code for building pile foundation wasn’t given; but several neutral points appeared along the pile; and the actual collapsible condition of loess is in sections

but not is sudden collapsible in the whole section above a certain neutral point as the traditional view states.