关键词: 淤泥质土, 深基坑, 支护桩深层水平位移, 混凝土支撑轴力, 变形监测

Abstract: In order to study the deformation characteristics and regulations of deep and large foundation pits under the conditions of deep and soft silty soil, combined with an example of a foundation pit project in a square in Hengqin, Zhuhai, according to the support design and surrounding environment of the support system in the project, and compares with the horizontal displacements of the deep pit supporting piles and the axial force monitoring data of the four concrete supports. The following conclusion could be drawn: the cumulative change of the deep horizontal displacement of the foundation pit supporting piles near the trestle slab exit is greater than that of other positions, and the maximum displacement depth is 0.75-0.93 times the excavation depth of the foundation pit, which is about 0.5 times the measured depth H; the cumulative value data of the concrete support axial force monitoring points on the same section as the oblique position of the maximum deep horizontal displacement is larger than that of other positions, and this point at this postion is also the monitoring point where the axial force of each support is the largest; the unbalanced of internal and external soil pressures caused by excavation and dump of foundation pits will make the internal support system withstand greater internal forces of the supporting structure, showing a signficant space-time effect; the results of this research can provide reference for the design and guidance of the support design and construction of the deep foundation pit similar to the deep muddy soil.

Key words: muddy soil, deep foundation pit, deep horizontal displacement of supporting pile, concrete support axial force, deformation monitoring