The developed flexible uniform pressure loading device and traditional rigid loading device are applied to large-scale geomechanical model test

of which loading effect is comparatively analyzed by using the stress nonuniformity coefficient ?. The test results show that

with the loading stress and the distance from the surface increasing

the stress nonuniformity coefficient ? decreases

and stress distribution tends to uniform. Comparing to the rigid loading method

flexible uniform pressure loading device is more beneficial to uniform stress dispersion and forming uniform stress field. With the flexible uniform pressure loading device being applied to the test

the stress field is nearly uniform where the depth from the surface is 300 mm in the test condition; and the ? is 0.086 when the initial stress has been applied; and the corresponding ? is 0.283 with rigid loading method applied in the test. Even though the distance from the surface is short or the loading stress is low

the flexible uniform pressure loading device also produces a good uniform loading effect

and when the on-load pressure is 0.28 MPa

the ? is only 0.174 where the depth from the surface is 150 mm. The device has the function of reducing range of boundary effect and improving model test accuracy.