How to timely identify cemented soil stability for Qianjiang tunnel breakthrough is discussed in terms of monitoring indices and monitoring range. Firstly
based on the plate theory and elastoplasticity theory
the water and earth pressures on the cemented soil are presented which can timely identify the cemented soil stability during shield tunnelling breakthrough as well as two indices
. Then
a failure mode for the cemented soil is put forward on the basis of existing failure modes to underlie the observation point layout
and verified by model test. The cemented soil stability can be estimated timely by calculating
from the measurement values when measuring points are distributed rationally.