During construction of shallowburied
tunnel with small crosssection in uppersoft and lowerhard strata with rich water,
rock breaking is hard to conduct in middle and lower benches, the arch foot of
the top heading is not located on the bedrock, so the primary support cannot be
closed in time, which may lead to the overall settlement of the primary support
of the top heading. Therefore, a case study is conducted on the exit section of
the Longquan tunnel, a excavation test section is set and the rock breaking
efficiency is taken as the main index to comparatively analyze the
feasibilities of four rock breaking technologies, namely, refitted blasting
machine, hydraulic fracturing, CO2 phase change
fracturing, and expansive agent fracturing, and the laws of tunnel convergence
and surface settlement after rock breaking by refitted blasting machine are
further analyzed. The results show the following: (1) The rock breaking
efficiency of CO2 phase change fracturing is the
highest, reaching 6 m3/h, followed by that of refitted
blasting machine(about 4 m3/h), and those of hydraulic
fracturing and expansion agent fracturing are lower, reaching 2 m3/h and 1.1 m3/h, respectively. (2) The
rock breaking technology of refitted blasting machine has many advantages such
as good stratum adaptability, controllable vibration, and easy trimming, which
can reduce the surface and crown settlement.
HUANG Lei, GONG Zhenyu, PU Heng, YANG Zebin, WANG Shuying
.
Rock Breaking Technology and Primary Support
Settlement Control of ShallowBuried
Tunnels with RichWater in UpperSoft and LowerHard Strata
[J]. Tunnel Construction, 2023
, 43(S1)
: 499
-505
.
DOI: 10.3973/j.issn.2096-4498.2023.S1.059
