To control the
stability of sinking of pressin caisson in soft soil layer, a
case study is conducted on an ultradeep underground
garage constructed by pressin caisson method in
Wenzhou. The change characteristics of tread pressure, slope pressure and ratio
of end resistance to total resistance during the sinking process of pressin caisson are studied by field measurement. The effects of two main
processes of static pressure sinking and soil extraction on the end resistance
are analyzed and compared with the standard theoretical values. The results
show the following: (1) The pressingsinking has little
effect on the pore water pressure, and the pore water pressure is significantly
affected by the properties of the formation beneath the foot blade, which is
mainly concentrated in the early stage of static pressure. (2) There is a
positive correlation between tread pressure and static pressure. Moreover, the
influence of static pressure on tread pressure becomes more pronounced with
increasing height of the soil plug in the well. (3) The slope pressure
increases with the static pressure. It is greatly affected by soil plug height
and decreases with the soil beneath blade foot hollowed. When the soil core
rate is in the range of 0.47－0.69, the sinking attitude
has a great influence on the slope pressure. (4) The vertical difference
between the tread pressure and the slope pressure is basically kept within 5－20 kPa, which is minimally affected by the sinking depth. The
working condition and state of caisson can be preliminarily judged by the
pressure difference curve. (5) The end resistance increases first and then
becomes stable with the sinking depth, and the increase is mainly concentrated
near the formation interface, which is basically consistent with the standard
calculation value. The distribution value of end resistance with depth is less
affected by static pressing and soil extraction, but the value is generally
lower than the standard value.
SUN Ruize, LIAO Shaoming, LIU Mengbo, ZHU Jiwen
. InSitu Measurements on End Resistance
of Press-in Caisson in Soft Ground:A Case Study of Wenzhou Caisson-Type
Underground Garage Project[J]. Tunnel Construction, 2023
, 43(S2)
: 310
-320
.
DOI: 10.3973/j.issn.2096-4498.2023.S2.035
