Investigation of failure prediction of open-pit coal mine landslides containing complex geological structures using the inverse velocity method

This paper describes a recent landslide event, which occurred at Liucheng village in Tianquan County, Sichuan Province, China, on July 15, 2018. The Laochang landslide described in this research is an outstanding and valuable reference for understanding the characteristics of such kind of landslides that are geologically similar to the landslide. The deformation characteristics of the landslide are investigated based on field investigations, drilled boreholes, and exploratory trenches. The 225 residents of 64 households living on the flat platform were threatened by the landslide. Therefore, to guarantee the safety of human life and property becomes the primary emergency task. The anti-sliding piles were taken to stabilize the landslide and mitigate impacts caused by the landslide. Based on the analysis of the monitoring data, the effectiveness of anti-sliding piles is evaluated. The results indicate that the anti-sliding piles are effective in increasing the stability of the landslide, and this work can provide a reference for similar slope engineering projects.

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Characteristics and emergency mitigation of the 2018 Laochang landslide in Tianquan County, Sichuan Province, China.

In order to systematically reveal the dynamic response characteristics of rock mass slopes subject to seismic excitation, time-domain and frequency-domain analyses are used to investigate the dynamic response of a bedded rock slope from multiple perspectives, using the two-dimensional numerical dynamic analyses. Based on the numerical simulation results, the influence of the weak bedded structural planes on the propagation characteristics of seismic waves in the slope is analyzed. The time-domain analysis suggests that the topographic and geological conditions have an influence on the dynamic response of the slope. The effects of ground motion direction on the dynamic response characteristics of the slope are identified. In addition, according to the frequency-domain analysis, the impacts of slope surface, elevation, and structural plane on the seismic response characteristics of the slope are also clarified. The intrinsic characteristics of the slope are investigated by using Fourier spectral analysis and modal analysis, and the deformation response characteristics of the slope are clarified. The relationship between different natural frequencies of the slope, the predominant frequency of the seismic wave, and the dynamic response characteristics of the slope is discussed. Moreover, the dynamic failure mechanism of the slope is analyzed. This work provides a reference for the seismic analysis of this type of slope.

Numerical Investigation on Dynamic Response Characteristics and Deformation Mechanism of a Bedded Rock Mass Slope Subject to Earthquake Excitation

The discrete technique combined with the upper bound approach is applied to analyze the stability of soil slopes with multiple layers in this paper. Based on the geometrical relationship derived from the normality requirement, an algorithm is proposed to determine the coordinates of discrete points on the failure surface. Specifically, these points are generated from the initial point to the terminal point. After completion of the discrete sliding surface, the sliding block is sliced by the vertical slice technique. Equations with integral form for rates of internal energy dissipation and external work are then derived. The scheme for calculation of the safety factor is presented by means of the strength reduction method and the optimization algorithm. Comparison analysis based on four examples under various conditions demonstrates the validity of the proposed method in addressing stability problem of slopes with multiple layers.

A Novel Method for the Stability Assessment of Soil Slopes with Multi-layers Based on the Upper Bound Limit Analysis

The settlement and deformation of an open-pit mine waste dump were investigated by using field monitoring and numerical methods. The creep parameters of fine soil sand in the dump fill were inverted using the steady Burgers creep model, and FLAC3D software was used to simulate the dumping soil construction and development program. The results show that the settlement displacement of the dump increases with the time of dumping soil and tends to be stable after 4 years. In the creep attenuation stage of the creep process, there is a big difference between the numerical calculation and the field monitoring results in the inversion process of fine-grained soil sand parameters. In the steady-state creep stage, the numerical calculation is consistent with the field monitoring value. The height of the fill has an influence on the settlement of the fill body of the dump and the time to reach the stability. The higher the filling height is, the greater the postconstruction settlement will be, and the longer it will take to reach stability. The pushing position of the fill body has a great influence on the settlement displacement of the dump. The time and efficiency of soil discharge can be shortened by optimizing the safe distance between the filling body and the river. Based on the numerical calculation results and the empirical settlement function, an analytical method for river channel location selection of internal dump is proposed.

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Investigation on the Deformation Law of Inner Waste Dump Slope in an Open-Pit Coal Mine: A Case Study in Southeast Inner Mongolia of China

Tunnel excavation has a substantial effect on the stability of rock slopes. The influence of tunnel excavation on the deformation and mechanical characteristics of a bedded slope is investigated by analysing the cumulative displacement, stress, and strain of the slope using the finite-element method (FEM) and field monitoring method. The deformation characteristics of the surrounding rock of the tunnel and slope with a supporting structure were analysed using the FEM under the conditions of support or without support. The results show that the deformation characteristics of the slope are controlled by its discontinuities. The deformation of the slope is mainly concentrated in the area above the second discontinuity; in particular, the deformation above the first discontinuity is the largest. In addition, the deformation and mechanical characteristics of the support structure are analysed. The supporting structure has influence on the deformation of the slope, which reduces the cumulative displacement, stress and strain. The shear strains of the second and third discontinuities are greatly influenced by the supporting structure. The mechanical properties of the tunnel support structure are controlled by the first discontinuity, and a stress concentration occurs near the first discontinuity. Moreover, based on the combination of the numerical and field test results, the deformation of the rock slope is closely related to the distance from the slope surface. Tunnel excavation mainly has a significant impact on the deformation of surface slope within a certain range, especially the slope deformation within the range of 4 m, which is the largest.

Zhuo Chen

Papers

Influence of Tunnel Excavation on the Stability of a Bedded Rock Slope: A Case Study on the Mountainous Area in Southern Anhui, China