Abstract：In order to study the law of support force change and failure mode of excavation face under seepage, a set of centrifugal model seepage test device was developed. Based on the tests of dry soil with different internal friction angle and saturated soil with different head pressure, the change rule of support force and progressive failure mechanism of soil in front of excavation face of different soil are studied, and the influence of the same soil seepage force on support force and instability response mechanism of excavation face is analyzed. The results show that with the increase of the displacement S , the supporting force P is divided into three stages: the rapid decline (S ＜ 1.5D %), the slow rebound after reaching the ultimate supporting force Plim (1.5D % ≤ S ≤ 3D %) and the steady value (3D % ＜ S). The support force of excavation face is smaller with the increase of internal friction angle, and increases linearly with the increase of head pressure; The instability mode of soil mass is a gradual process from local failure to global failure related to the internal friction angle of soil mass, soils with different internal friction angles have different response times during iteration of soil arch and seepage force exacerbates soil arch iteration speed and destruction. Finally, it is verified that the seepage force is anisotropic.
