In order to effectively reduce the construction cost
and the overbreak amount by drilling and blasting method, and improve the
drilling and blasting construction technology, the operation mode of the rockdrilling
jumbo is studied, and it is concluded that when the rockdrilling jumbo is used for tunnel drilling and blasting excavation,
the external angle when drilling the peripheral blasting holes is difficult to
be controlled, and the tunnel overbreak amount is always large due to the
influence of the boom structure of jumbo, unclear field sight and relatively
long visual distance. Furthermore, comparison and contrast is made on the
overbreak amounts induced by matching construction of long and short blasting
holes under different construction conditions, such as primary support closely
following tunnel face and that not following tunnel face. It is concluded that
under the premise of ensuring construction safety, the method that retaining a
certain length of tunnel without construction drilling for primary support and
using matching drilling and blasting technology of long and short blasting
holes can effectively control the amount of tunnel overbreak during drilling
and blasting by using rockdrilling jumbo. The results
show that the maximum overbreak amounts of Grade Ⅱ and Ⅲ, Grade Ⅳ and Grade Ⅴ surrounding rocks when using long and short blasting holes are 12
cm, 19.5 cm and 21.5 cm less than that when using long blasting hole, respectively.
FANG Junbo
,
LIU Hongzhen
,
MA Liuchuang
. Tunnel Overbreak Control Technology by Rock drilling
Jumbo with Long and Short Blasting Holes[J]. Tunnel Construction, 2020
, 40(11)
: 1642
-1648
.
DOI: 10.3973/j.issn.2096-4498.2020.11.013
