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Rapid flow-like landslides frequently occur in mountainous regions. To mitigate the disasters caused by these landslides, it is crucial to develop robust numerical models that can accurately predict their run-out processes. Models based on the material point method (MPM) offer significant advantages in simulating large deformation issues in geomaterials, including landslides. However, applying these models to accurately simulate real-world rapid flow-like landslides remains a challenge, primarily due to the complexities involved in handling the three-dimensional (3D) sliding bed boundary. This paper introduces a novel 3D MPM model specifically designed for simulating rapid flow-like landslides that propagate across curved beds. The constraints of the sliding bed on the landslide are imposed by the boundary nodes close to the bed. These boundary nodes carry information about the normal vector of the sliding bed, derived directly from the digital terrain model (DTM). Furthermore, the model integrates a hybrid formulation that combines the Full Lagrangian Implicit Particle (FLIP) method with the Particle In Cell (PIC) method, facilitating a stable solution for the velocity and position of material points. The effectiveness of the proposed model is confirmed through a numerical analysis of a rigid block sliding down an inclined plane and an experiment of sand flow on a curved bed. The simulation results from these two benchmark scenarios align closely with both analytical and experimental data, attesting to the validity of the model. The model is then applied to analyze a rapid flow-like landslide that occurred in Gansu Province, China, characterized by a curved sliding bed. The outcomes illustrate the model's capability to efficiently capture the landslide's climbing and turning motions induced by the meandering topography. Moreover, it successfully reproduces the main deposition characteristics observed in the field, demonstrating the model's strong suitability for simulating the propagation of rapid flow-like landslides on naturally curved beds. [ABSTRACT FROM AUTHOR]

On 5 April 2021, a high-position landslide occurred in Tiejiangwan, Liujiang Town of Hongya County, Sichuan Province, China. The detached mass transformed into a debris avalanche traveled about 1300 m with an elevation difference of 665 m and caused three fatalities. Then landslide deposits were initiated by continuous rainfall and evolved to a debris flow five days later, forming a secondary disaster chain. The rapid characterization of a landslide-debris flow chain (LDC) is a critical step in remediation works and future early warning of failure. This paper proposes a rapid disaster information integration and assessment method for providing information on LDC occurrence, failure mechanisms, and potential hazard-affected areas via examining and characterizing the Tiejiangwan LDC based on multi-method including geomorphological mapping, structural characterization, kinematic analysis and numerical simulation. The results suggested that the first landslide initiated from a mountain ridge that experienced historical deformation extended over the fractured argillaceous siltstones. Constrained by three discontinuity sets, the failure mode was determined as planar failure along a sub-vertical defect. The cause of first landslide can be attributed to a jointed effect of structural plane, tectonic activity, terrain and slope structure, while rainfall is the dominating triggering factor. Deposits with loose structure subjected to persistent rainfall and gully topography contribute to the occurrence of secondary debris flow. Using UAV and LiDAR identification, the unstable elements in the surrounding cliffs of the source area are derived and a three-dimensional simulation was implemented to detect the energy, velocity, height and reach of detached blocks. The proposed method leads to rapid characterization of LDC and assists the evaluation of cliff instability of these environments. Highlights: We proposed a rapid and integrated assessment system for landslide-debris flow chain occurrence, failure mechanisms, and potential hazard-affected areas identification. Quantitative study was conducted on the evolution from landslide deposits to debris flow. 3D simulation was performed to reveal the runout behaviors of surrounding potential dangerous rockfall areas. [ABSTRACT FROM AUTHOR]

Based on field geological survey and unmanned aerial vehicle (UAV) photography, this paper studied the inherent causes, intrinsic mechanisms, and kinematic characteristics of a catastrophic landslide of dissolved and fractured rock slope in a mountainous area of Southwestern China. The discrete element method (DEM) model of representative volume element of fractured rock mass considering karst existence was developed with its micromechanical parameters calibrated from laboratory element tests. The coupled finite difference and discrete element methods (FDM-DEM) were then employed to simulate deformation and failure evolution and collapse development of the rock slope with both internal and externally triggering factors properly addressed. The kinematic characteristics of mobile collapse debris flow were analyzed, and the numerical simulation results were validated by laboratory physical model test. The results show that the internal causes were mainly manifested in slope structure, lithology combination, karst, and fracture development, among which the unfavorable interaction disintegrated rock masses. The primary external cause was the staged underground coal-mining operations underneath the collapsed body, which led to large cracks appearing at the back edges of the slope. The maximum velocity of mobile collapse debris was about 65 m/s with the maximum travel distance of more than 600 m. Numerical simulation results matched well with both field forensic investigation and laboratory physical model test results. The findings would help further understand the deformation and failure process of fractured rock slope subject to underground mining and provide technical reference for accurate assessment and proper mitigation of similar landslide disasters. [ABSTRACT FROM AUTHOR]

This paper takes Fen-Wei Basin (FWB) as a case to study the ground fissures controlled by normal fault. Based on the field investigation, geophysical exploration, drilling, GNSS data and numerical calculation, the characteristics and mechanism of ground fissures originated from the hanging wall of normal faults are revealed. The results show that the distribution of ground fissures in the hanging wall and heading wall of the active faults is not uniform. Ground fissures are mostly distributed in the hanging wall of active faults and show a linear distribution on the surface, their strike is consistent with the fault, mainly characterized by vertical offset and horizontal tension. Ground fissures destroy the farmland and building foundation through which they pass and cause the rupture or displacement. In profile section, the ground fissure shows the characteristics of normal faults and dislocates the strata, and is connected with the underlying faults. Numerical analysis shows that the vertical displacement of normal fault activity in hanging wall is much larger than that in heading wall, which is the reason that tectonic ground fissures mainly originate from hanging wall. The range of dangerous area of ground fissures is controlled by the depth of fault, the strength of the ground fissures disaster is mainly controlled by the activity of fault. The formation of the ground fissures originated from the hanging wall of the fault experienced three stages: the main fault activity stage, the secondary fault activity stage and the fissure formation stage. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing technology has become an effective technical method of developing tight oil reservoirs, such as an oilfield in Mahu, China. However, numerical simulation of the actual fracture seam network remains problematic. In this paper, we have simulated hydraulic fractures in the Urho Group of the Mahu target layer and analyzed the characterization of the rock mechanics parameters. The results show that Young's modulus of the Wuerhe domain ranges between 18 and 58.5 GPa, with an average of 32.4 Gpa, the Poisson's ratio is between 0.21 and 0.38, with an average of 0.31, the brittleness index is between 21.0 and 89.0, with an average of 44.3, and the hydraulic fracturing can form a multi-branch crack modification. The designed direction of horizontal wells in the area is north-south, and the horizontal stress difference is between 4.2 and 9.8 MPa, which facilitates easy fracturing of the reservoir and reforming of a complex seam network. Simulation of the artificial seam network helps to optimize the reasonable parameters of fracturing and the development parameters of horizontal wells in the Mahu 1 well area. [ABSTRACT FROM AUTHOR]

Owing to the heavy rainfall, a landslide occurred at the Anqian Iron mine, at 18:00(UTC + 8) on November 24, 2019, in China. The landslide was about 3.0 × 104 m3 and caused damage to the road of transporting waste materials. Failure characteristics and the mechanism of this landslide were analyzed in this study. The landslide area was divided into three parts: the rear tension cracking area, the middle sliding deformation area, and the front colluvium area. A contact-free measuring technique using the new ShapeMetrix3D system was applied and 204 joints were analyzed based on equal-angle stereographic projection. Thus, a conceptual model of the mechanism of the landslide was constructed and the formation process of the landslide was divided into three stages: the first shearing and dislocation stage; the second sliding, front bulging, and rear tractive cracking stage; and the third local rock mass collapse and colluvium depositing stage. Numerical modeling was performed to discover the landslide mechanism by progressively reducing the shear strength of rock mass. The results showed that the original slope was stable, whereas heavy rainfall triggered the landslide, and the predicted failure surface matched closely the field investigations. The factor of safety obtained by real three-dimensional analyses was slightly higher than that obtained by plane problem analyses, and the difference was attributed to the three-dimensional effect of the landslide. This paper also presents the results obtained from the parametric analysis in order to understand the impact of shear strength parameters on the overall stability of the slope. [ABSTRACT FROM AUTHOR]

The peak particle velocity (PPV) is an important indicator for predicting blasting excavation disturbances. However, the PPV distribution in the deep underground space is significantly different from that on the outdoor ground. Therefore, it is difficult to predict the underground PPV by Sadovsky's vibration formula. The PPV sidewall distribution characteristics were studied during site blasting in an underground cavern in the Taohuazui mine in China, and a similar numerical model was used to verify the site test data. We derived a PPV prediction formula for the underground cavern sidewall surrounding rock using a mechanical analysis model of a simply supported plate and beam in combination with dimensional analysis. The model considered derived boundary constraints, comparison with site measured data, the value predicted by Sadovsky's vibration formula, and numerical simulation results. The results showed that the PPV distribution on the middle 1/3 section of the underground cavern sidewall showed a "platform" or "bulge" different from the curve from Sadovsky's vibration formula. The PPV amplification coefficient in this section was distributed in a drum shape. The PPV prediction formula for the middle section of the sidewall derived in this paper was highly consistent with the data measured on-site and the numerical simulation results. The mechanical analysis model with a simply supported plate and beam included an underground cavern sidewall length–height ratio of 5 and effectively supplemented the PPV prediction formula for the middle section of the traditional underground cavern sidewall. [ABSTRACT FROM AUTHOR]

The friction pendulum bearings (FPB) begin to be used in railway bridges in China. In one earthquake region in China, the shear pins of FPB are required to be well to provide the enough shear force and stiffness under service loads (such as the vehicle forces being less than 170 kN in the longitudinal direction and 40 kN in the transverse direction) or small earthquake loads with a peak ground acceleration (PGA) being less than 0.1 g, however, are cut off to isolate seismic energy under large earthquake loads with a PGA being larger than 0.2 g. It is necessary to identify the appropriate strength of FPB shear pin to satisfy the above requirements. This paper selected the simply supported bridges on a single-line railway in the above earthquake region as the study object, which had a span length of 32 m and two height types of piers (8 m and 25 m). A prototype finite element model (FEM) and a scaled FEM were numerically analyzed, and a scaled experimental model was tested on shake table for each bridge. The results of them were compared with each other to validate the rationality of all models and to achieve the appropriate strength of FPB shear pin. The results show that the appropriate strengths of FPB shear pins are 540 kN in the longitudinal direction and 300 kN in the transverse direction for the bridge with the pier height of 8 m. Likewise, 350 kN and 270 kN are determined as the appropriate strengths of FPB shear pins for the bridge with the pier height of 25 m in the longitudinal and transverse directions, respectively. The numerical method of FEM is correct based on the experimental validation, and can be used to identify the appropriate strengths of FPB shear pins for other railway bridges. [ABSTRACT FROM AUTHOR]

Based on the rock mass quality classification, this paper proposes a new prediction formula for the attenuation parameters of blasting vibration velocity in jointed rock masses. A parametric sensitivity study is also conducted while considering a variety of influence factors, including joint angle, joint spacing, and joint stiffness. Compared to the existing blast-related standard in China, in which the attenuation parameters are merely derived from rock hardness, without considering the joint characteristics of rock masses, the proposed prediction formula is proved to be a more promising approach to carry out accurate blasting design and blasting safety assessment. [ABSTRACT FROM AUTHOR]

The Qianjiangping landslide occurred on July 13, 2003 when water level in the Three Gorges Reservoir in China reached 135 m a.s.l. for about 1 month. Thirteen people on the slope and 11 fishermen on boats in the nearby area were killed by this landslide and its wave. As a typical case, the Qianjiangping landslide is researched extensively, but the wave itself was studied much less. In this paper, a fluid-solid coupling model based on general moving objects (GMO) collision model and renormalisation group (RNG) turbulent model were employed, simplifying the sliding motion of the Qianjiangping landslide as a rigid body circular motion whose validity was verified by comparing with actual survey conditions related. Numerical simulation analysis shows that in the Qianjiangping landslide event, the solid-fluid energy-transferring rate was 5.97 %, while the motion of sliding mass could push and raise water body. The maximum-modelled wave run-up generated by the Qianjiangping landslide was 40.4 m (up to 175.4 m a.s.l.), while the maximal observed one was 39 m. It was the solitary wave, and the wave celerity was 32∼36 m/s or so. The hazardous river length of impulse wave was estimated to be 12.6 km, where wave height was more than 1 m high. The fluid-solid coupling numerical model employed by this paper can provide important reference for wave generated by other landslides around the world. Research of the landslide-generated wave is very significant in landslide hazard reduction and prevention. [ABSTRACT FROM AUTHOR]

The development of an expansion double spherical seismic isolation (DSSI) bearing by modifying the fixed DSSI bearing is described in this paper. The expansion DSSI bearing is characterized by its good energy dissipation and horizontal displacement capacity and has been successfully integrated into the seismic design of several important engineering projects in China. It is envisioned to be used as a substitute for ordinary expansion bearings in continuous girder bridges to distribute the longitudinal earthquake action among all the piers. Its development, configuration and working mechanism are introduced first. The test method and the seismic performance of an expansion DSSI bearing are then briefly described. A theoretical analysis followed by a numerical analysis for an actual four-span continuous girder bridge are provided as an example, and it is concluded that the expansion DSSI bearing can be integrated into the seismic design of continuous girder bridges. [ABSTRACT FROM AUTHOR]

On the April 9 of 2000, a gigantic rapid rock slide-debris avalanche occurred in Bomi, Tibet. Some 280-300 × 10 m of material travelled 10 km within 10 min and dammed the Yigong River, forming a 2.9 × 10 m³ barrier lake. Wind tunnel testing was undertaken to determine the aerodynamic parameters involved, from the initial rock slide-fall to its point of impact. The paper reports the numerical analyses undertaken and discusses the significance of the air-cushion effect. It is concluded that Yigong rapid rock slide-debris avalanche 'flew' in the air for about 12.9 s from its detachment from the source to its collision with the floor of the Zamunong gully at 3,317 m asl. The velocity of the avalanche mass at the point of detachment was some 81.8 m/s and the collision velocity approximately 117 m/s. [ABSTRACT FROM AUTHOR]

Rainfall depth (or intensity) of the same frequency should follow a non-decreasing relationship with rainfall duration. However, due to the use of finite samples and sampling error, rainfall frequency analysis could yield rainfall intensity (depth)–frequency (IDF, DDF) curves of different durations that might intersect among them. Results of this kind violate physical reality and it is more likely to occur when rainfall record length gets shorter. To ensure the compliance of the physical reality, this paper applied the scale-invariant approach, in conjunction with constrained regression analysis, to circumvent intersections in rainfall IDF or DDF curves. Rainfall data of various durations at rain gauge in Hong Kong are used to demonstrate the procedure. Numerical investigation indicates that the proposed procedure yields more reasonable results than those based on the conventional frequency analysis, especially when only a small sample of data are available. [ABSTRACT FROM AUTHOR]