When tunneling in a narrow chamber with microcracks
and extremely high water pressure, water gushing or shaft flooding occurs. To
address this problem, a case study is conducted on the chamber of the bottom
car yard of inclined shaft No. 1 of the Gaoligongshan tunnel on the DaliRuili
railway. The site conditions are complex and include water pressure as high as
7.6 MPa, large montmorillonite content, poor groutability, limited drainage
capacity of the shaft bottom, difficult grouting and water plugging, and high
construction requirements. Therefore, field tests are performed regarding
selection and matching, equipment disassembly and hoisting, antioutburst measures for extremely high water pressure, and standards
for starting and ending water plugging in advance. The following conclusions
are obtained: (1) An advance water plugging and grouting scheme is proposed.
This scheme includes rational step distance, water sealing, inside first and
then outside, process connection, interval grouting, water source locking,
increasing grouting holes, and local strengthening. (2) A highpower, narrowbody crawler hydraulic drill
equipped with a stepless variablespeed ultrahighpressure, lowflow
doubleliquid pump is customized for fast construction
of repeated equipment disassembly and hoisting in narrow spaces. (3) The
solutiontype modified ureaformaldehyde
resin is adopted, with 23 times hydrostatic pressure
as the final grouting pressure, improving the groutability of the formation and
achieving a satisfactory water plugging effect. (4) The insitu water pressure test predicts water inflow in front, and based on
the actual drainage capacity in the shaft, a scientific and reasonable water
control principle of "plugging as the main and limited discharge" is
determined. The permeability coefficient is calculated using the borehole water
pressure test to determine the advance grouting starting standards, and the
water plugging ending standard is determined based on the permeability
coefficient when achieving a satisfactory grouting effect. (5) The optimal
grouting cycle length is determined to be 25 m, which can achieve the highest
comprehensive construction efficiency.
GAO Guangyi
,
ZHAI Kangbo
,
GU Qingtian
.
Key Technology for Water Blocking and Grouting Construction
in Chamber of Bottom
Car Yard of Microcrack Vertical Shafts Under Extremely
High Water Pressure: A Case Study of Vertical Shaft
No. 1 of
Gaoligongshan
Tunnel on DaliRuili Railway
[J]. Tunnel Construction, 2024
, 44(5)
: 1086
-1095
.
DOI: 10.3973/j.issn.2096-4498.2024.05.016
