###### Abstract  
The occurrence and development of a landslide is a gradual process of destruction, causing huge losses to people's lives and property. The shear strength of the shear zone gradually decreases to the residual state during the sliding process but it can recover to a certain extent during a relatively stable period. In a landslide, more than one slide usually occurs; however, after the first slide stops, it can enter a dormant period. The sliding surface can then experience a self-healing strength recovery phenomenon; this self-healing phenomenon has a significant impact on the reactivation of the landslide. Relevant studies have shown that the strength of the sliding surface is slightly greater than the residual strength when a landslide is reactivated; however, the explanations provided by these studies have not been sufficiently systematic. In this study, focusing on the undisturbed slide zone soil of the Huaipa landslide in Sanmenxia City, the \"shear-pause-shear\"-test scheme is adopted. The soil is subjected to 3 h, 6 h, 12 h, 24 h, and 72 h healing shear tests, and combined with the SEM microstructure characteristics of the shear surface, to explore the internal mechanism of self-healing. The results show that the landslide soil exhibits strong self-healing strength recovery characteristics; however, these strength recovery characteristics decrease rapidly after experiencing a very small displacement. The strength recovery was strongly correlated with the vertical stress and healing time. With increasing vertical stress, the strength recovery value of the soil increases. Under low pressure, the strength recovery is small, and under high pressure, the strength recovery is obvious. With increasing healing time, the strength recovery increases; however, the increase in the amplitude diminishes and ultimately approaches zero with increasing healing time. A \"healing phenomenon\" occurs in the shear surface of slide zone soil after a short period of time. A shear strength value greater than the residual strength can be used to check the landslide design, which can effectively reduce costs. m 2024 14 484 10.10. The most classical ring shear apparatuses are the Bishop ring shear apparatus and the Bromhead ring shear apparatus. The former is divided into upper and lower shear boxes, and the shear surface is located at the contact between these boxes. During the shear process, the upper shear box does not move while the lower shear box rotates. Meanwhile, the shear boxes of the latter apparatus are not divided. During the shear process, the torque is applied to the load plate at the top of the sample via air pressure or voltage, such that the sample produces torsional shear, and the shear surface is located at the upper part of the sample. Different ring shear apparatuses have their own advantages and disadvantages; however, it is indisputable that ring shear apparatuses have greater advantages with respect to simulating the shear characteristics of landslides under large-displacement conditions. The particles at the shear surface are parallel to the shear direction to the greatest extent after shearing; during the shearing process, the shear surface area remains constant, such that the sample is subjected to a uniform force, and the residual strength is more accurate [2]. In this study, the German WILLE ARS-3 ring shear apparatus is used to simulate the residual strength characteristics of the slide zone soil under large displacement shear conditions. When a landslide occurs, subsequent revival movement will shear along the existing sliding surface which is controlled by the residual strength. In the design of slope preventive measures, the residual strength is generally considered. If the landslide is revived and recovers to a state of residual strength within a short time, this strength could be used as a remedy for landslide design and remediation. The recovered strength is greater than the residual shear strength, which increases the resisting strength.