To study the degradation characteristics of the gypsum
breccia that surrounds tunnels in a seasonally supplemented groundwater
environment, a case study on gypsum breccia is conducted for a tunnel project
in Shanxi. Wettingdrying cycle tests for 1, 3, 6, and
10 cycles are carried out considering the effect of flow rates of 0, 10, and 20
L/h. The law describing the corrosion and water absorption behavior of gypsum
breccia under the action of the wettingdrying cycles
at different flow rates is systematically analyzed in this paper. Based on the
results of uniaxial and triaxial compression tests, the law describing the
degradation of the mechanical parameters of gypsum breccia under different
wettingdrying cycles and flow rates is then explored
in more detail. The results show the following. (1) The wettingdrying cycle and water flow cause degradation of the gypsum breccia.
The effect of the wettingdrying cycle on the gypsum
breccia mainly involves a reduction in the degree of connection between
particles, whereas the water flow aggravates the corrosion of the gypsum
breccia and erodes the loose particles on the surface of the rock. (2) The
mechanical indices of gypsum breccia including the uniaxial compressive
strength, elastic modulus, friction angle, and cohesive strength show a
downward trend as the flow rate and the number of wettingdrying cycle increase. When the flow rate is 20 L/h, after 10 wettingdrying cycles, the uniaxial compressive strength of the gypsum
breccia is reduced by 72.86%, the elastic modulus is reduced by 75.67%, the
friction angle is reduced by 70.69%, and the cohesion strength is reduced by
57.58%. The elastic modulus is degraded the most, followed by the uniaxial
compressive strength, friction angle, and cohesion.
LIU Zhiguo
,
JIANG Song
,
HUANG Ming
,
CHEN Zefeng
,
LAN Xingbin
. A Law for Degradation of Mechanical Properties of
Gypsum Breccia Surrounding Tunnels in a Complex Groundwater Environment[J]. Tunnel Construction, 2021
, 41(7)
: 1150
-1158
.
DOI: 10.3973/j.issn.2096-4498.2021.07.008
