To explore the rock heating and fracturing mechanism
in microwaveassisted rock breaking, five groups of microwave irradiation tests
are conducted on basalt samples under various microwave power and irradiation
times, which provide the temperature distribution and fragmentation state of
rock surface. For deducing the rockbreaking mechanism,
the COMSOL multiphysical fieldmodeling software is
used to simulate the distribution of electric and temperature fields inside the
rock. Test results show that the increase in the microwaveemission power and irradiation time increase the rocksurface temperature, breaking area, breakingpoint depth, crack quantity, and crack length. Furthermore,
simulation results reveal the following: (1) The electricfield intensity in rock decreases sharply when the microwave is
transmitted from the microwave antenna to the upper rock surface and exhibits
an inverted cone distribution. (2) Additionally, the rockfragmentation damage under microwave irradiation is revealed to be
mainly attributed to the electricfield intensity. The
electricfield power results in an uneven distribution
of energy density in different rock parts, causing a change in the temperature
gradient and foreign thermal expansion, which lead to fragmentation damage. The
evolution of rockfragmentation damage can be divided
into three stages. Based on the regression analysis of mathematical models for
the heating process of rock samples, the microwaveemission
power has considerable influence on temperaturedependent
characteristics. A microwave irradiation power of 26.645 kW is shown to cause
fragmentation damage of rock in a short time, indicating the best irradiation
effect.
LIU Chaoyin
,
LU Gaoming
,
ZHOU Jianjun
,
YAO Huayan
,
JIANG Lijie
,
FAN Wenchao
. Heating and Fracturing Characteristics of Rocks Under
Microwave Irradiation[J]. Tunnel Construction, 2023
, 43(8)
: 1348
-1359
.
DOI: 10.3973/j.issn.2096-4498.2023.08.009
