Abstract: In landslide stability analysis and design calculation, the residual strength value of slip zone soil is often selected, but many studies have found that the slip zone soil has self-healing phenomenon in the holding period, which is manifested as the increase of shear strength. For the red bed landslide dominated by creep, the application of recovered strength in the stability analysis of a reactivated landslide should be considered. The shear-hold-shear experiments are carried out on soil samples from a typical red bed landslide to determine the healing of shear zones under different vertical stresses and holding durations. The experimental data show that, the strength recovery occurs in the tests under different pressures, but the recovered strength will lose in very small shear displacement; the strength recovery value of the shear zone becomes larger and larger with the increase of holding time; self-healing of shear zones is more dependent on holding time than vertical stresses. The obtained friction coefficient values is fitted with the empirical formula of fault strength recovery, and the value of constant A under different vertical stresses can be obtained. The value of constant A can be applied to stability analysis of the reactivated landslide.

Key words: red bed landslide, slip zone self-healing, residual strength, regression analysis, factor of safety