Heat transportation will change the mechanical properties of rock and soil materials considerably in subsurface engineering applications such as radioactive waste repositories

geothermal energy extraction and underground oil/gas storage. Thermal properties of rocks

soils and buffer materials

including thermal conductivity

thermal expansion coefficient

specific heat capacity

play a crucial role in design and evaluation of safety performance of these projects. The thermal expansion coefficient tests are conducted on sandstone with bedding planes by using the independently developed instrument for thermal expansion coefficient of rocks. The evolution of axial and radial thermal expansion coefficients of rocks are studied. The results show that for rock samples with horizontal beddings

with the change of temperature

axial thermal expansion coefficient is about 14×10?6 ℃?1

while about 9×10?6 ℃?1 in radial direction under uniform expansion. The axial thermal expansion coefficient is about 1.56 times as large as the radial thermal expansion coefficient

and the rock sample shows obvious anisotropy. Compared with rock samples with horizontal beddings

the samples with inclined and vertical beddings shows no significant difference in axial thermal expansion coefficient

but their radial thermal expansion coefficients are larger. Under the same temperature

the order of radial expansion coefficient from big to small is vertical

inclined and horizontal beddings. Because of the existence of beddings

the expansion properties of sandstone and compositions of beddings are different

which leads to the difference of axial and radial expansion coefficients. The results may provide a helpful reference for better understanding the thermo-mechanical behaviors of rocks.