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Plowing refers to the phenomenon by which a landslide displaces and pushes the path material forward. Despite its importance in shaping the dynamics of many rapid flow-like loess landslides, the mechanism of plowing is not fully understood. Therefore, this paper presents an improved numerical model based on the material point method (MPM). This model takes into account the interactions between the landslide mass and the path material. The reliability of this model was validated by simulating two granular column collapse experiments involving interaction with an erodible mass. The model was then applied to analyze the plowing dynamics of the Ximiaodian loess landslide in Jingyang County, Shaanxi Province, China. A series of well-designed simulations were conducted to investigate this specific landslide event, contributing to a deeper understanding of the plowing phenomenon in loess landslides. The simulation results show that our model can satisfactorily simulate the plowing process of the Ximiaodian landslide. The plowing process of a rapid-flow loess landslide is proposed to consist of four distinct stages: 1) the collision stage, when the landslide strikes the terrace, resulting in the bending of its strata; 2) the shear failure stage, characterized by significant plastic shear deformation within the bent strata, resulting in the formation of multiple shear failure planes; 3) the steady plowing stage, during which the deformation structure in the affected terrace stabilizes and plowing continues in a steady pattern; and 4) the stopping stage, when the propagation of the disturbed terrace gradually stops. Furthermore, the disturbed terrace zone exhibits three distinct deformation structures. In the rear part, a stable zone develops where the terrace layers are compressed. However, due to the compressive forces exerted by the overlying loess, no significant shear deformation is observed. The middle part is the shear failure zone, characterized by the formation of multiple shear failure planes. The front part is the upheaval zone, where the terrace layers are slightly bent and tilted. • An improved MPM model is proposed to simulate the plowing process of rapid flow-like landslides. • The plowing mechanism of a real loess landslide is analyzed by the MPM model for the first time. • The plowing process of a rapid flow-like loess landslide consists of four stages. • Three distinct deformation structures are formed in the disturbed terrace zone during the plowing process. [ABSTRACT FROM AUTHOR]

Accurate acquisition of in-situ soil water content is of great significance for mastering the water content distribution of unsaturated soil and understanding soil engineering properties. The actively heated fiber-optic (AHFO) method has recently become a research focus because of the capability to realize distributed and real-time measurement of soil water content. However, most reported AHFO systems have been coupled to distributed temperature sensing (DTS) which does not allow for remote measurements with high spatial resolution. In this paper, a new AHFO method based on the quasi-distributed fiber Bragg grating (AHFO-FBG) technique is proposed for the large-scale in-situ measurement of soil water content. An AHFO-FBG in-situ monitoring system is developed which consists of a sensor module, heating module, data acquisition and transmission module, and data processing module. The established system is applied to a loess slope in Yan'an City, Shaanxi Province, China to monitor its water content distribution in real time. The effectiveness of the monitoring system is verified and the water content distribution of the monitored loess slope are analysed. The in-situ measurement results indicate that in the spatial dimension, the water content in the top and bottom of the slope is low, and that near the scarp is high; in the time dimension, the water content in winter is low while that in autumn and spring is high. The monitored results also suggest that soil water evaporation in winter can significantly enhance the spatial distribution difference of soil water content. • The AHFO-FBG soil water content in-situ monitoring system was developed. • The in-situ monitoring system was applied to a loess slope in Yan'an, China. • The loess water content distribution is mainly affected by climate and topography. • The AHFO-FBG method is much better than neutron scattering method in surface soil. • Large-scale and remote measurement of soil water content was achieved by the system. [ABSTRACT FROM AUTHOR]