%0 Journal Article
%A FEI Yi
%A LI Wang-hui
%A ZHAO Chun-feng
%A WANG You-bao
%A WU Yue
%T Theoretical Solution to Borehole Contraction Caused by Unloading in Anisotropic Sandy Soil
%D 2020
%R 10.11988/ckyyb.20191118
%J Journal of Yangtze River Scientific Research Institute
%P 168-174
%V 37
%N 4
%X Radial unloading-induced borehole contraction is caused in the drilling process of bored pile. On the basis of the SMP yield criterion and the non-correlated flow rule, the solution for the stress and displacement fields in two stress-state conditions of plastic zone around the vertical borehole is deduced with the coefficient <i>K</i><sub>0</sub> of lateral earth pressure considered. Parameter analysis shows that the <i>K</i><sub>0</sub> and internal friction angle <i>φ </i>of soil have a great influence on the emergence and development of plastic zone as well as the radius <i>r</i><sub>e</sub> and <i>r</i><sub>p</sub> of plastic zone. The relative displacement and stress of borehole wall increase linearly along with the increase of drilling depth with different values of <i>K</i><sub>0</sub> and mud's unit weight <i>r</i><sub>mud</sub>. The relative displacement of borehole wall intensifies with the growth of <i>K</i><sub>0</sub>, while declines with the rising of <i>r</i><sub>mud</sub>. However, the radial and circumferential stresses of borehole wall do not change with <i>K</i><sub>0</sub>. In addition, the range of plastic zone around the vertical borehole hardly changes along the depth in sandy soil, and the plastic radius<i> r</i><sub>p</sub> has a remarkable influence on the circumferential stress. The theoretical solution presented in this paper is of theoretical significance for the unloading problem of borehole in initial in-situ stress field of sandy soil.
%U http://ckyyb.crsri.cn/EN/10.11988/ckyyb.20191118