Abstract
Due to the development of the scale of tractor-ploughed terraces, terraces have been increasing in number, while global climate change is causing frequent extreme rainfall events in the Loess Plateau, resulting in many terrace landslides. To study the mechanism and process of shallow landslides and deep slip surface of terraces induced by extreme rainfall in loess hill and gully area, we conducted a laboratory model test of a terrace under artificial rainfall and used the Swedish arc strip method. The research results are as follows. The mechanism of shallow landslides in terraces is rill erosion accelerating rainfall infiltration, suspending the slope, and increasing its bulk density. The destruction process of shallow landslides can be roughly divided into six processes, and the earth volume of the landslide is 0.24 m3. The mechanism of the deep sliding surface in terraces occurs under the combined action of water erosion and gravity erosion. The soil moisture content increases, which decreases the anti-sliding moment and increases the sliding moment, and the safety factor becomes less than the allowable limit for terraces. The deep sliding deformation area of the terrace was 0~1.0 m below the slope surface, slip surface radius was 1.43 m, the slip surface angle was 92°, and the deep sliding surface began to form earlier than terraced shallow landslides. The displacement of the characteristic points increased from the slope top, to the slope center, and to the slope foot, with maximum displacements of 40.3, 15.5, and 6.0 mm, respectively.
Highlights
With the implementation and promotion of slope-to-terrace projects, large areas of sloping fields have been built into terraced fields [1]
The construction of terraced field projects has changed the minor features of sloping fields, reducing surface runoff and increasing soil infiltration, effectively improving soil moisture content, which plays a crucial role in reducing soil erosion and increasing grain yield in the surrounding areas [2,3]
Due to the large-scale development of tractor-ploughed terraces, terraces have been constantly increasing in number, while global climate change has led to frequent occurrences of extreme rainfall events in the Loess Plateau, resulting in many terrace landslides [6]
Summary
With the implementation and promotion of slope-to-terrace projects, large areas of sloping fields have been built into terraced fields [1]. When extreme rainfall produces runoff on a field’s surface, the terraces seriously erode This kind of hillslope is featured by collapsibility, strong water permeability, vulnerability, and so on, so rainfall conditions can induce shallow landslides, which seriously affect agricultural production [8]. An in-depth study of the process and mechanisms of shallow landslides and Water 2021, 13, x FOR PEER REVIEW deep slip surface of terraces under extreme rainfall is theoretically significant for di2saosfte22r prevention and mitigation and has practical value for agricultural production in Northern Shaanxi [9,10,11,12,13]. We selected terraces as the research object, and indoor model tests and the Swedish arc strip method were used to study the mechanism and mode of shallow landslides and deep sliding surfaces in terraces under extreme rainfall conditions. The research is important for the agricultural development of the loess hilly and gully region as it provides: (1) a reliable theoretical basis and abundant experimental data for slope collapse and instability prevention, and disaster mitigation, monitoring, and forecasting of terraces; (2) parameters for the optimized design of terraces; and (3) a method for studying multi-level terraces and terraced landslides in the basin
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