The blasting excavation of
tunnels crossing underneath urban areas has disadvantages such as large
blasting disturbance, slow construction speed, and high risk. Therefore, a case
study is conducted on Nanhu station-Wanshou
Road station and a tunnel section of Phase Ⅱ of
Chongqing metro line 10. Construction and blasting methods are compared and
optimized. The blasting construction is mainly conducted according to the order
of "scheme design, blasting construction, vibration monitoring,
information feedback, optimization, and adjustment". Specific
countermeasures are proposed for difficulties encountered during blasting
excavation process. The research results indicate the following: (1) The
blasting cross-section is divided into upper and lower
parts, the lower part is set as cutting zone, and the cutting hole structure
and blasting sequence are optimized. Under the premise of blasting vibration
speed of no less than 2 cm/s,
this blasting scheme increases the maximum amount of single stage detonating
charge and cyclic advance compared to conventional blasting methods. (2) The
blasting sequence of upper cross-section first and then
lower cross-section rapidly connects each construction
process, and it is more beneficial to large-scale
mechanical operations and achieve high efficiency than bench-excavation method. (3) The blasting scheme of lower cross-section first and then upper cross-section
provides condition for one-time shotcrete supporting,
avoiding subsequent arch feet suspension, arch frame damage, and untimely
support, which is more conducive to construction quality and safety.
ZHAO Guangping
. Rapid Construction
Technology of Controlled Blasting for Tunnels Crossing Underneath Urban Areas[J]. Tunnel Construction, 2024
, 44(S1)
: 368
-380
.
DOI: 10.3973/j.issn.2096-4498.2024.S1.040
