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In September 2013, the third phase of impoundment of the Xiangjiaba Hydropower reservoir to 380 m was conducted. In July 2014, large numbers of cracks appeared in many parts of Suijiang landslide seriously threatening the safety of 4300 residents. Understanding the spatiotemporal evolution characteristics of the landslide and analyzing the deformation mechanism could help in evaluation of the stability and prevent secondary disasters. On the basis of detailed geological survey data, monitoring data, and spatiotemporal evolution characteristics, this study comprehensively analyze the deformation mechanism and propose a new conceptual model of the Suijiang landslide in Xiangjiaba reservoir, China. This study concludes that the backfilling of the L gully blocked the drainage blind ditch such that the groundwater level of the entire slope was elevated, which was the main triggering factor. As the rainfall increased, the rate of deformation also increased, and the greatest deformation corresponded to the annual occurrence of the rainy season, which is the main influencing factor of deformation. The reservoir water level was a secondary influencing factor. The abrupt drop in reservoir water level had a greater impact on deformation compared with that of a rise in reservoir water level. Influenced by differences in consolidation characteristics caused by uneven backfilling of the L gully, the filling area produced deformation firstly. The rear part forms “active force transfer area” and the resistant-sliding zone forms “passive extrusion area”. The Suijiang landslide showed a sliding mode of “creep pushing-bending bedding shearing”. The slope continues to deform affected by external factors. It is suggested that further resistant-sliding measures will be incorporated to control further development and improve stability.

Acoustic emission (AE) characterization is an effective technique to indirectly capture the failure process of quasi brittle rock. In previous studies, both experiments and numerical simulations were adopted to investigate the AE characteristics of rocks. However, as the most popular numerical model, the moment tensor model (MTM) cannot be constrained by the experimental result because there is a gap between MTM and experiments in principle, signal processing and energy analysis. In this paper, we developed a particle-velocity-based model (PVBM) that enabled direct monitoring and analysis of the particle velocity in the numerical model and had good robustness. The PVBM imitated the actual experiment and could fill in gaps between the experiment and MTM. AE experiments of marine shale under uniaxial compression were carried out, and the results were simulated by MTM. In general, the variation trend of the experimental result could be presented by MTM. Nevertheless, the magnitudes of AE parameters by MTM presented notable differences of more than several orders of magnitude compared with those by the experiment. We sequentially used PVBM as a proxy to analyse these discrepancies and systematically evaluate the AE characterization of rocks from the experiment to numerical simulation, considering the influence of wave reflection, energy geometrical diffusion, viscous attenuation, particle size and progressive deterioration of rock material. The combination of MTM and PVBM could reasonably and accurately acquire AE characteristics of the actual AE experiment of rocks by making full use of their respective advantages.

In order to study the dynamic characteristics and destabilisation damage mode of the accumulation body slope under the action of ground vibration, and to provide theoretical guidance and technical support for the optimization design of reinforcement of similar slopes, a large shaking table model (scale 1:16) test with a specific accumulation body slope was conducted as a prototype. The dynamic response and deformation characteristics of the model slopes were observed by inputting sine, Wolong, and EI Centro waves to the bottom of the model slopes, respectively. The test results showed that in the vertical direction and on the slope surface, the acceleration amplification factor (AAF) increased with the increasing of altitude, and presented a nonlinear change. In the horizontal direction, the AAF increased with distance from the slope surface. There was also a slope surface amplification effect with the AAF reaching its maximum at the slope shoulder. Similar laws were obtained after numerical simulation of the prototype slope by FLAC3D software. Different types of seismic waves exhibited different effects on the AAF. Sine waves showed the largest effect, followed by Wolong waves, and EI centro waves exhibited the smallest effect. The AAF of the modelled slope was different for different input wave frequencies. As the input frequency of Sine waves increased, the AAF increased first and then decreased. This change coincided with the AAF reaching its maximum value at 25–30 Hz. The AAF of the modelled slope varied when the input wave amplitude values were different. When the AAF reached its maximum value, the input amplitude was 0.4 g. By analysing the slope failure progression, it showed that the slope of an accumulation body began with local sliding at the front edge, followed by internal sliding of it, and the overall sliding.

Water-induced strength deterioration of rock mass is a crucial factor for rock slope instability. To better show the degradation process of rock slope water–rock interaction, we used bentonite as a water-sensitive regulator to build a new rock-like material that matches the features of water-induced strength degradation based on the cement-gypsum bonded materials. Twenty-five schemes of the material mixture proportion were designed using the orthogonal design method considering four factors with five variable levels, and a variety of experiments were conducted to obtain physico-mechanical parameters. In addition, one group of rock-like material proportion was selected and applied to the large-scale physical model test. The experiment results reveal that: (1) The failure mode of this rock-like material is highly similar to that of natural rock masses, and the physico-mechanical parameters vary over a wide range; (2) The bentonite content has a significant influence on the density, elastic modulus, and tensile strength of rock-like materials; (3) It is feasible to obtain the regression equation based on the linear regression analysis to determine the proportion of rock-like material; (4) Through application, the new rock-like material can effectively simulate or reveal the startup mechanism and instability characteristics of rock slopes under water-induced degradation. These studies can serve as a guide for the fabrication of rock-like material in the other model tests.

Coal mining may lead to ground subsidence in a long term and is widely distributed, which can cause environmental damage and other disasters. Predicting the dynamic process of ground subsidence in real time is very important for offering theoretical or technical guidance to deal with the consequences of mining. In this study, we developed a prediction method for dynamic ground subsidence using a time function model that considers two stages of surface subsidence and reflects the law of surface subsidence in goaf. We applied the model to the Barapukuria mine, and our simulation shows that the prediction results are in good agreement with the monitoring data. Our results suggest that the dynamic development of the ground subsidence basin may be an effective measure to assess the loss of ground and provide early warning of oncoming hazards.

The subsidence caused by coal mining could cause the destruction of roads and houses, and even the failure of infrastructures. Understanding of the mechanism of coal mining subsidence may provide early protecting to infrastructures on coming failure, but dynamic analysis of subsidence due to coal mining is currently needed. In this study we apply particle image velocimetry (PIV) method to reveal strata movement and subsidence according to the prototype and indoor physical model similarity experiment of Henan. Our result shows magnitude of the subsidence of overlying strata during the coal mining at different excavation thickness, that more coal mining thickness may produce more subsidence, and that shallower coal may cause more significant subsidence. Our result suggests that further PIV test combined with field monitoring data may be an effective measure to study subsidence mechanism and pattern helping to predict disaster caused by subsidence.

Using residual soil from the Shanghecun landslide in the western Henan Province, shear creep tests of residual soil samples with different rock contents (RCs) were performed to explore the creep characteristics, creep rate, and long-term strength of the residual soil. The test results indicate that the residual soil samples with different RCs display typical creep characteristics. With increasing RC, both the instantaneous deformation and the total creep deformation of the residual soil gradually decrease. The shear strain of the residual soil increases gradually with increasing shear stress for the different RCs. With increasing time, the slope of the isochronous stress-strain curves of the residual soil samples with different RCs increases gradually. The Burgers model can simulate the rheological process of the residual soil samples with different RCs. The RC has a significant effect on the shear strength and the long-term strength of the residual soil. With increasing RC, the shear strength and the long-term strength of the residual soil gradually increase, with the long-term strength being approximately 39%-63% of the shear strength.

The soil slopes in nature are normally unsaturated, heterogeneous, and even carry cracks. In order to assess the stability of slope with crack under steady unsaturated flow and non-uniform conditions, this work proposes a novel discretization-based method to generate the rotational failure mechanism in the context of the kinematic limit analysis. A point-to-point strategy is used to generate the potential failure surface of the failure mechanism. The failure surface consists of a series of log-spiral segments instead of linear segments employed in previous studies. Two kinds of cracks—open cracks and formation cracks—are considered in the stability analysis. The maximum depth of the vertical crack is modified by considering the effect of the unsaturated properties of soils. According to the work–energy balance equation, the explicit expression about the slope factor safety for different crack types is obtained, which is formulated as a multivariate nonlinear optimization problem optimized by an intelligent optimization algorithm. Numerical results for different unsaturated parameters and non-uniform distribution of soil strength are calculated and presented in the form of graphs for potential use in practical engineering. Then, a sensitivity analysis is conducted to find more insights into the effect of unsaturation and heterogeneity on the crack slopes.

Sandy cobble soil has characteristics including a large internal friction angle, high permeability coefficient, and poor fluidity, which can result in serious tool wear, groundwater spilling, and transportation difficulties during shield construction. A subway in Luoyang is presented as an example case of shield construction. The optimal soil-water ratio of the bentonite slurry is 1:10 based on a sand and cobble stratum in the shield construction, and the optimal expansion duration is 18 h. Large-scale shear, slump degree, and permeability tests were conducted on a sodium-based bentonite slurry mixed with the sandy cobble soil. It was found that, with increasing slurry injection rate, the viscosity of the sandy cobble soil increased; the sand and stone separation phenomenon gradually vanished; the shear strength, internal friction angle, and permeability coefficient non-linearly decreased; and the slump degree non-linearly increased. The slurry injection rate necessary to meet the friction requirement of sandy cobble soil in the shield construction was 17%; the slurry injection rate necessary to meet the permeability requirement was 14%; and the slurry injection rate necessary to meet the fluidity requirement was 13% – 17%. The total thrust and cutter torque of the shield were found to be reduced by approximately 1/3, and the earth pressure balance maintained relatively well after the sandy cobble soil was mixed with the bentonite slurry, these points being remarkably significant to the high-speed advance of shield construction. This study is important with respect to solving issues concerning sandy cobble layers in subway shields.

Analyzing the mechanisms of soil instability in tunnels due to sudden water ingress is essential for construction safety. This kind of problem belongs to the category of seepage deformation, mostly due to the near tunnel range of water pipeline blowing cracks and heavy rainfall flooding rainwater into the tunnel. Distinguished from general infiltration behavior, the relevant problems have the characteristics of rapid occurrence and short action time. This study develops a 3D fluid–solid coupling model for soil deformation in tunnels with water ingress, grounded in Biot’s theory and Darcy’s law while considering water level variations within the tunnel. The governing equations are discretized in space and time, and the model’s accuracy is validated through comparison with actual measurements from a Zhengzhou subway project. The study analyzes pore pressure, stress-deformation responses, and surface settlement patterns in surrounding soil and rock mass under soil–water coupling. The findings show that (1) the tunnel cavern, as a seepage source, has minimal impact on the lateral settlement trough width, while seepage mainly affects the vertical deformation of surrounding rock; (2) pressure dissipation exhibits hysteresis in clay strata; (3) water ingress increases soil saturation and decreases effective stress, resulting in persistent surface settlement until drainage. There is a minimal discrepancy between model-calculated and measured settlements.