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Soil slopes located in more rainfall region have been damaged significantly in the previous earthquakes due to the earthquake-induced excess pore water pressure (EPWP), which is among primary factors causing slope failure. For the purpose of evaluating seismic behaviors of an unsaturated soil slope at various groundwater levels, we established a simple approach for calculating earthquake-induced EPWP, which is importable to the numerical simulation software through the custom interface. Based on this, we investigate the seismic performance of the unsaturated soil slope. It is observed that the seismic performance of the slope has much difference at various groundwater levels; the slope deformation at a high groundwater level increases greatly while the groundwater reduced the vibration of the slope. Also, it was found that the slope shows different failure processes with the groundwater influence: the failure of slope with high groundwater is mainly the flow slide and tensile crack around the slope toe while the slope presents the collapse and slip failure without the groundwater influence. Moreover, by strict similarity law formula derivation, the shaking table test of two slope models, one without groundwater and one with groundwater, was performed, and the test results show that our calculation results are accurate and reasonable, and our establishment calculation method of EPWP is practical and convenient.

To investigate the seismic performance of a wind turbine that is influenced by both the ice load and the seismic load, the research proposes a numerical approach for simulating the seismic behavior of a wind turbine on a monopile foundation. First, the fluid-solid coupled equation for the water-ice-wind turbine is simplified by assigning reasonable boundary conditions and solving the motion equation, and the seismic motion equation of the wind turbine is developed. Then, on this basis, we propose a simplified 3D numerical model that can simulate the interactions among the wind turbine, water and sea ice. By conducting shaking table tests, the results demonstrate that the established numerical model is effective. Finally, we investigate the effect of the boundary range and ice thickness on the seismic performance of a turbine under near-field and far-field seismic actions. Research results illustrate that ice changes the distribution form of the hydrodynamic pressure. Moreover, the thickness of the ice greatly influences the seismic behavior, while the influence of the ice boundary range is only within a certain range. Additionally, the ice load decreases the energy-dissipating capacity of the wind turbine, so the earthquake resilience of the wind turbine is significantly decreased.

Sea ice is one of the main loads acting on a wind turbine tower in areas prone to icing, and this threatens safe working life of the wind turbine tower. In our study, a simplified calculated model of ice, wind turbine tower, and water dynamic interaction under earthquake action was proposed, which could avoid to solve a large number of nonlinear equations. Then, the seismic behaviour of the wind turbine tower with and without the influence of sea ice was investigated, and we found that the influence of the greater mass of the sea ice on the seismic response of a wind turbine tower should be considered when the wind turbine tower is designed in an area with thick ice. With the influence of the most unfavourable ice mass, the deformation and energy dissipation capacity of the wind turbine tower are decreased, and the wall thickness or stiffening rib thickness should be increased to improve the seismic performance and ductility of the wind turbine tower; the shear force and bending moment increased significantly on the wind turbine tower, and the shear force changes at the bottom of the wind turbine tower and position of action of the sea ice: attention should be paid to the wind turbine tower design at these positions. Finally, we conducted the shaking table test, and verified the rationality of our proposed simplified model.

An accurate slope prediction model is important for slope reinforcement before the disaster. The k-nearest neighbor (KNN) algorithm, as a simple and effective nonparametric machine learning method, is widely applied in classification recognition. In our study, the k-nearest neighbor (KNN) algorithm is improved to reduce its sample dependence and improve the robustness of the algorithm, and then the prediction model of the slope stability is proposed based on the improved k-nearest neighbor (KNN) algorithm. Extensive experimental results show that our proposed prediction model achieves high prediction performance in this regard. Moreover, a comparison between our proposed prediction model and the finite element method, which is the classical theoretical method of slope stability, was made, which will provide an important approach to predicting the slope stability for slope engineering. Finally, shaking table test of a slope model is conducted to evaluate whether the slope is stable or not, and the experimental results are in good agreement with the prediction results of our proposed prediction model, which further demonstrates its effectiveness.

On October 10, 2018, a big landslide occurred on the right bank of the Jinsha River in Baige Village, Polo Township, Jiangda County, Tibet (hereafter called the Baige landslide), which blocked the Jinsha River, forming a barrier lake. Afterward, the landslide dam broke, producing a flood. On November 3, the rear wall of this landslide failed again, also blocking the Jinsha River and creating a bigger barrier lake. Then, by local people, a discharge channel was excavated on the top of the landslide dam, making lake water cross over the discharge channel. As the water flow gradually increased, the landslide dam broke again, producing a more severe flood, resulting in huge economic losses downstream. The purpose of this study is to understand the cause of this landslide and predict the future stability of its head scarp, providing some support for the control scheme in the later stage. A digital orthophoto map (DOM) and a digital elevation model (DEM) of the landslide were created using an unmanned aerial vehicle. Then based on the DOM and DEM, the geometric characteristics of the landslide were described. Multi-phase Planet 5 images were used to infer the development process of the landslide. Finally, the cause of the landslide was analyzed based on the rainfall data and the limit equilibrium calculation. The results show that the Baige landslide was a self-weight creeping event, and its development and trigger were independent of the rainfall. Before the landslide, the slope experienced five stages of evolution: steady deformation, slow deformation, rapid deformation, steady deformation, and rapid deformation. The limit equilibrium calculation indicates that the stability coefficient of the middle section of the head scarp is the lowest, thus which should be cut down as a priority. This study provides a typical example of a self-weight creep type landslide, and an important reference for prediction and prevention of similar large landslides in the Tibetan Plateau, southwestern China.

Using the seismic data collected since 2010 by the China Earthquake Networks Center and based on the maximum likelihood method, we analyzed the temporal and spatial anomalies of the b-value prior to the MS 6.0 Luxian earthquake on September 16, 2021. The results are as follows. (1) The Luxian earthquake broke the historical record of no M ≥ 6 earthquake occurring in the Huayingshan fault zone, revealing that the Huayingshan fault zone still has the seismogenic ability of medium and strong earthquakes. (2) Before the MS 6.0 Luxian earthquake, the b-values around the focal areas exhibited increasing–peaking–decreasing anomalous characteristics, indicating that this is an effective method of predicting the occurrence of moderate to strong earthquakes in the region. (3) In the past 10 years, the b-values of the middle segment of the Huayingshan fault zone have been relatively low, but the b-value of this section may be in an abnormal stage of slow increase, indicating that this segment may be in a stage of stress accumulation and concentration and is preparing for moderate to strong earthquakes. The middle segment of the Huayingshan fault zone may become the site of moderate to strong earthquakes in the future. We should continue to pay attention to it.

Saline soil affected by earthquakes and groundwater can lead to subgrade subsidence and collapse in highway construction. Consequently, considering the potential activity of the waste slag and magnesia, new cementitious composite materials used in solid saline soil were developed in our study. The unconfined compressive strengths of the saline soil solidified by the new cementitious composite materials with a combination of magnesium oxide, calcium oxide, gypsum, and mineral powder and cement were investigated, and the optimum dosage proportion of the new cementitious composite material for solidifying saline soil was determined; then the SEM, EDS, and XRD of the saline soil solidified by the new cementitious composite materials and cement were analysed. The research result showed that the saline soil solidified by our newly developed cementitious composite material showed compact internal structure and uniformly distributed soil particles; moreover, the new cementitious composite material exhibited a favourable solidifying effect on harmful ions in saline soil, and the Cl− trapping capacity of the new cementitious composite materials was stronger than that of cement. Finally, our developed cementitious composite material was applied to saline soil subgrade strengthening, and the displacement, acceleration, excess pore water pressure, and damage degree of the subgrade strengthening by our newly developed cementitious composite materials decreased remarkably; therefore, our newly developed cementitious composite material can improve the seismic behaviour of the saline soil subgrade and show potential future engineering application value.

In this article, based on the nonlinear elastic-plastic finite element model for metro station, considering the structure-soil dynamic interaction, the influence laws of the burial depth on the dynamic response and failure mode of the metro station structure under near and far-field earthquakes are studied. We found that the influence of burial depth on the deformation of the metro station may be omitted after a specific value of the burial depth. With the increasing of the burial depth, the acceleration dynamic amplification factors of the metro station structure decreses. At last, indoor shaking table test for metro station was done, through which we determined the position of initial failure and the failure mode of the metro station structure under earthquake.

Using the seismic data collected since 2010 by the China Earthquake Networks Center and based on the maximum likelihood method, we analyzed the temporal and spatial anomalies of the b-value prior to the M S 6.0 Luxian earthquake on September 16, 2021. The results are as follows. (1) The Luxian earthquake broke the historical record of no M ≥ 6 earthquake occurring in the Huayingshan fault zone, revealing that the Huayingshan fault zone still has the seismogenic ability of medium and strong earthquakes. (2) Before the M S 6.0 Luxian earthquake, the b-values around the focal areas exhibited increasing-peaking-decreasing anomalous characteristics, indicating that this is an effective method of predicting the occurrence of moderate to strong earthquakes in the region. (3) In the past 10 years, the b-values of the middle segment of the Huayingshan fault zone have been relatively low, but the b-value of this section may be in an abnormal stage of slow increase, indicating that this segment may be in a stage of stress accumulation and concentration and is preparing for moderate to strong earthquakes. The middle segment of the Huayingshan fault zone may become the site of moderate to strong earthquakes in the future. We should continue to pay attention to it.

Based on the newly compiled and mostly complete unified earthquake catalogue for China’s seas and adjacent areas, further information was obtained about the structural shape and dip angle of the Benioff zone in the Ryukyu Islands subduction zone during the different subduction stages. In addition, using the damped regional stress tensor inversion method, we were able to investigate the complex stress field characteristics and the dynamic significance of the shallow and intermediate earthquakes in the Ryukyu Islands subduction zone. The results show that the tectonic stress field of the Ryukyu Islands subduction zone was extensional along the subduction direction in the northern area of the Tokara Strait and was compressional along the subduction direction in the southern area of the Tokara Strait. The R value of the shallow stress field of the Okinawa Trough was low, and the σ3 was stable in the NNW direction with a small dip angle (>30°). The type of stress field in the shallow part of the Okinawa Trough transitioned from strike-slip type to normal fault type from north to south, reflecting the difference in the degree of development of the trough, and the southern segment of the trough began to transform into the expansion stage. The northeastern portion of the study area and southeast Taiwan constituted the high R value (0.68–0.87) region where the σ2 had tensile components. The stress state was biaxial tension–uniaxial compression, and the principal compressive stress was determined to be in the SEE direction with a large dip angle (>30°). The σ1 in northeast Taiwan exhibited a nearly vertical (>60°) plunge, while the σ2 and σ3 were nearly horizontal. The σ2 was thrust in the ENE–WSW direction, and the σ3 was extended in the NNW direction. Through this research, a greater understanding has been gained of the seismicity characteristics and shape of the Ryukyu Islands subduction zone. Supplementary research has also been completed on the focal mechanism solution and stress field of the Ryukyu Islands subduction zone. Finally, this research is important for earthquake hazard analysis and earthquake engineering safety evaluation in this area.