Engineering
problems such as instability of excavation face, poor dumping, screw conveyor
stuck, and pebble in chamber may arise when large diameter shield is driving in
sandpebble layer. Meanwhile, excessive torque of shield cutterhead and
screw conveyor may be caused in the sandpebble layer.
Therefore, the requirements for conditioning of the fluidity of sandpebble soil are more stringent. In this paper, the reasonable
conditioning parameters of sandpebble soil are
obtained through laboratory experiments. Based on the experimental results, the
flow characteristics of conditioned sandpebble soil
are calibrated using discrete element method. The threedimensional 〖JP2〗model
of soil chamber and screw conveyor is established by SolidWorks, and the
conveying performance of conditioned sandpebble soil
is simulated by EDEM. Conclusions are as follows: (1) When the 20% foam
injection ratio is used for conditioning, the slump value is 14.8 cm, and the
flowability and pressure maintaining capacity of soil are all ideal. (2) The
soil velocity in soil chamber shows an inverted triangle distribution with the
opening of the screw conveyor as the vertex, and the velocity in the inverted
triangle area is faster, which is 2~8 cm/s, while the velocity on both sides of
the soil chamber is slower, which is basically below 2 cm/s. (3) The particle
pressure in the screw conveyor is far less than that in the soil chamber, which
indicates that the fluidity of sandpebble soil is
poor. (4) The particle velocity is slower than that of the screw blade, which
leads to 44.5 %～47.7 % of the transportation efficiency
of the screw conveyor.
YANG Yi, LI Xingchun, LI Xinggao, CAI Zhiyong, LIU Hongzhi
. Transportation Performance of Conditioned SandPebble
Soil in Earth Pressure Balance Shield[J]. Tunnel Construction, 2021
, 41(S2)
: 299
-305
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.038
