For decades, displacement detection based on Global navigation satellite system (GNSS) has increasingly been an important part of deformation monitoring for applications, such as dams, bridges, and high-rise buildings. Automatic identification and extraction of three-dimensional (3D) displacements from GNSS kinematic positioning can provide a basis for emergency response decision-making and play a crucial role in natural and secondary disasters. However, due to the limitation of single epoch positioning accuracy, automatic detection of displacement from GNSS kinematic positioning results is still a challenge. To resolve this, we propose an enhanced K-means clustering method to detect displacements from GNSS kinematic positioning, which identifies the displacement by clustering and obtains displacements from adjacent clusters. Results from simulation and field experiments have demonstrated the effectiveness of the proposed method. The accuracy of 3D displacement extraction from GNSS real-time kinematic positioning can reach millimeter level.

A translational landslide comprised of nearly horizontal sandstone and mudstone interbeds occurred in the Ba River basin of the Qinba–Longnan mountainous area. Previous studies have succeeded to some extent in investigating the formation mechanism and failure mode of this type of rainfall-induced landslide. However, it is very difficult to demonstrate and validate the previously established geomechanical model, owing to lack of landslide monitoring data. In this study, we considered a translational landslide exhibiting an unusual morphology, i.e., the Wobaoshi landslide, which occurred in Bazhong, China. First, geological conditions of this landslide were determined through field surveys, and the deformation and failure mode of the plate-shaped main bodies were analyzed. Second, long-term monitoring was performed to obtain multiparameter monitoring data (width of the crown crack, rainfall, and accumulated water pressure in cracks). Finally, an equation was developed to evaluate the critical water height of the multistage bodies, i.e., h_cr, based on the geomechanical model analysis of the multistage main sliding bodies, and the reliability of this equation was verified using long-term relevant monitoring data. Subsequently, the deformation and failure mode of the plate-shaped bodies were analyzed and investigated based on numerical simulations and calculations. Thus, the monitoring data and geomechanical model proved that the accumulated water pressure in cracks makes cracks open much wider and causes the plate-shaped bodies to creep. Simultaneously, an optimized monitoring methodology was proposed for this type of landslide. Therefore, these research findings are of reference significance for the rainfall-induced translational landslides in this area.

Hydraulic fracturing (HF) test has been widely used to determine in situ stress. The use of a conventional continuum method for this purpose has raised considerable controversies concerning field tests, particularly in the determination of the maximum horizontal principal stress under preexisting fractures. Fracture mechanics methods are very promising when considering preexisting cracks. However, most fracture mechanics methods do not include the effects of confinement on fracture parameters that depend on confining stress. In the present paper, we proposed a modified approach based on fracture mechanics for stress determination considering the relation between fracture toughness and confining stress based on the Rummel and Abou-Sayed methods. Then, we conducted true triaxial hydraulic fracturing tests under different stress ratios for granite and sandstone specimens to verify the proposed approach. The observed typical pressure-time curves indicate that in the conducted hydraulic fracturing tests, the steady fracture growth was attained. Moreover, we demonstrated that the stress ratios influence crack orientations. The horizontal maximum principal stresses determined using the modified Rummel method achieve the lowest relative error compared with other considered stress estimation approaches. This modified fracture mechanics method could be used as a potential alternative approach to obtain a considerably more precise estimation of the maximum horizontal stress in hydraulic fracturing stress determination.