###### Abstract
[15] believed that, after a short rest of one day, the reactivated residual strength increased with the increase in OCR under a given normal effective stress, but it was lost after a small shear displacement. The overconsolidation effect on reactivated residual strength at a lower stress was more prominent than that at a higher stress. [PERSON] et al. [16] explored the strength recovery mechanism of remolded lime soil and found that the lime improved the recovery strength, and the structure of the shear surface was analyzed via microscopy. [PERSON] and [PERSON] [17] believed that, after long period of reconsolidation, the shear zone volume changes as a result of the influence of secondary compression, resulting in significant strength recovery. Studies have also shown that plasticity has an important effect on strength healing. [PERSON] et al. [18] concluded that samples composed of silt have characteristics of strength recovery. [PERSON] et al. [19] also found that the strength recovery of low-plasticity slide zone soil dominated by silt and sand is more obvious under lower effective vertical stress. [PERSON] et al. [20] investigated the strength recovery characteristics of remolding normal consolidated kaolinite and bentonite with a healing time of 4 days and showed that the strength recovery of high-plasticity clays (bentonite) is more pronounced even with shorter healing time. [PERSON] et al. [21] performed a 230-day strength recovery ring shear test on two soils with different plasticity. The results showed that the strength recovery increases with increasing plasticity and that this strength recovery characteristic decreases rapidly after experiencing a very small displacement. [PERSON] and [PERSON] [22] used a healing time of 30 days and found that Montona flysch had greater recovery strength than Rosazzo flysch because of the strong plasticity of Montona flysch, which is similar to the findings of [PERSON] et al. [21]. [PERSON] et al. [23; 24] conducted strength recovery tests for three soils with different plasticity for healing times of 1, 3, 7, 15, and 30 days. The results showed that the high-plasticity soil had higher recovery strength than the low-plasticity soil and that the friction angle of the soil did not increase within a healing time of 3 days, while the friction angle of the soil only increased by 1\({}^{\circ}\) after a healing time of 30 days. The formation of the Huaipa landslide was accompanied by soil creep characteristics [25]. The creep characteristics include the destruction and recovery between particles. These two effects determine that the long-term strength of soil should be considered in the actual engineering design, and the long-term strength reflects the self-healing phenomenon of the shear surface, which is reflected in the value of the increase in the shear strength relative to the residual strength. In this study, undisturbed slide zone soil of the Huaipa landslide in Sammenxi City is examined, and the ring shear apparatus is used to control the healing time, vertical pressure, and other factors. The generating factors of the healing effect of the landslide sliding surface are then analyzed, and the internal mechanism of the strength recovery is further explored using scanning electron microscopy (SEM) characteristics.