During construction of Wanrong tunnel of Menghua
railway crossing siltyfine sand stratum, many problems
such as tunnel face collapse, sand leakage caused by untight advanced jet
grouting piles, and large deformation caused by primary support steel frame in
loose sandy stratum are encountered, which would affect the project quality and
safety. Accordingly, relevant countermeasures are adopted as follows. (1) The
stepped excavation support method and the advanced jet grouting pile curtain
are adopted. (2) The steel shims are installed at grille steel frame feet to
increase stress area, and further stabilize the steel frame and reduce the
deformation induced by loose sandy stratum. (3) The long invert trestle is
adopted to ensure that the distance between closed ring of invert structure and
tunnel face be less than 20 m and that between secondary lining and tunnel face
be less than 50 m. (4) The highpressure water sprayer
is used to improve the humidity in the air, avoid the moisture loss of siltyfine sand stratum, and reduce its natural stability. (5) The
backfilling grouting behind the primary support is adopted to effectively
reduce the collapse phenomenon and control the settlement deformation within 5
cm. The engineering practice results show that the abovementioned technical measures can effectively ensure the construction
quality and safety of Wanrong tunnel crossing siltyfine
sand stratum.
SU Hui
. Key Construction Technologies for Wanrong Tunnel of Menghua
Railway Crossing SiltyFine Sand Stratum[J]. Tunnel Construction, 2020
, 40(S2)
: 225
-232
.
DOI: 10.3973/j.issn.2096-4498.2020.S2.029
