Development characteristics and failure modes of reactivated ancient landslides in the Sichuan–Tibet transportation corridor,China

The risk of reactivated ancient landslides in the Sichuan–Tibet transportation corridor in China is significantly increasing,primarily driven by the intensification of engineering activities and the increased frequency of extreme weather events.This escalation has resulted in a considerable number of fatalities and extensive damage to critical engineering infrastructure.However,the factors contributing to the reactivation and modes of destruction of ancient landslides remain unknown.Therefore,it is imperative to systematically analyze the developmental characteristics and failure modes of reactivated ancient landslides to effectively mitigate disaster risks.Based on a combination of data collection,remote sensing interpretation,and field investigations,we delineated the developmental attributes of typical ancient landslides within the study area.These attributes encompass morphological and topographic aspects,material composition,and spatial structure of ancient landslides.Subsequently,we identified the key triggers for the reactivation of ancient landslides,including water infiltration,reservoir hydrodynamics,slope erosion,and excavation,by analyzing representative cases in the study area.Reactivation of ancient landslides is sometimes the result of the cumulative effects of multiple predisposing factors.Furthermore,our investigations revealed that the reactivation of these ancient landslides primarily led to local failures.However,over extended periods of dynamic action,the entire zone may experience gradual creep.We categorized the reactivation modes of ancient landslides into three distinct types based on the reactivation sequences:progressive retreat,backward thrusting,and forward pulling–backward thrusting.This study is of great significance for us to identify ancient landslides,deepen our understanding of the failure modes and risks of reactivated ancient landslides on the eastern margin of the Tibetan Plateau,and formulate effective disaster prevention and mitigation measures.

响应面法优化超声波辅助水蒸气蒸馏提取丁香精油研究

采用Box-Behnken响应面法对超声波辅助水蒸气蒸馏提取丁香精油进行优化。选用超声波功率、料液比、颗粒度、萃取时间为考察因素,以丁香精油的提取率为检验指标进行单因素试验,采用Box-Behnken响应面试验设计法优化考察四因素三水平及其交互作用对丁香精油提取率的影响。最佳工艺条件为:超声波功率为300W,颗粒度为150目,料液比为1∶15(g/mL),萃取时间为1h。在优化操作条件下分别三组试验提取丁香精油,平均提取率为19.637%±0.42%。

Landslide susceptibility mapping using an integrated model of information value method and logistic regression in the Bailongjiang watershed,Gansu Province,China

Bailongjiang watershed in southern Gansu province, China, is one of the most landslide-prone regions in China, characterized by very high frequency of landslide occurrence. In order to predict the landslide occurrence, a comprehensive map of landslide susceptibility is required which may be significantly helpful in reducing loss of property and human life. In this study, an integrated model of information value method and logistic regression is proposed by using their merits at maximum and overcoming their weaknesses, which may enhance precision and accuracy of landslide susceptibility assessment. A detailed and reliable landslide inventory with 1587 landslides was prepared and randomly divided into two groups,(i) training dataset and(ii) testing dataset. Eight distinct landslide conditioning factors including lithology, slope gradient, aspect, elevation, distance to drainages,distance to faults, distance to roads and vegetation coverage were selected for landslide susceptibility mapping. The produced landslide susceptibility maps were validated by the success rate and prediction rate curves. The validation results show that the success rate and the prediction rate of the integrated model are 81.7 % and 84.6 %, respectively, which indicate that the proposed integrated method is reliable to produce an accurate landslide susceptibility map and the results may be used for landslides management and mitigation.

Predicting landslide scenes under potential earthquake scenarios in the Xianshuihe fault zone, Southwest China

Earthquake-induced landslides can seriously aggravate the earthquake's destructive consequences and have caused widespread concern in recent decades. The Xianshuihe fault is a large active left-lateral strike-slip fault in the southeast margin of Qinghai-Tibet Plateau, Southwest China, where the frequent strong earthquakes have brought abundant geo-hazards. This study focuses mainly on exploring and predicting the landslide scenes induced by the potential earthquakes. Firstly, the sophisticated Newmark model is improved through landslide cases induced by the Ms7.9 Luhuo earthquake in 1973 to adapt the field seismotectonics of the Xianshuihe fault zone. Then, it is used to predict the landslide scenes under one speculated potential earthquake scenario with the similar focal mechanism with the Luhuo earthquake. The preliminary results show that the slope displacement resulted from Newmark model can reflect spatial distribution characteristics ofearthquake-induced landslides. The predicted potential earthquake-induced landslide scenes present an obvious extending trend along the Xianshuihe fault. The landslide hazard is greater in the northeast regions than southwest regions of the Xianshuihe fault, where there are more complex topographic conditions. The study procedure will be a helpful demonstration for exploration and prediction of landslide scenes under potential earthquakes in the regions with high seismic activity.

“模拟电子电路”课程教学模式的改革与实践

"模拟电子电路"是工程实践性较强的电类专业基础课程,通过对课程体系和实验方式方法的分析,本文提出了"以集成电路为主线,以应用为目的"的课程体系,采用理论实践一体化的教学模式,以便携式多功能实验平台为支撑,通过理论教学、课堂实验、课程实验相结合的教学模式,激发了学生学习兴趣和学习动力,提高了学生理论综合实践创新能力。

“一带一路”背景下蚕丝文化在对外汉语教学中的应用

实施“一带一路”倡议背景下,蚕丝文化教学应成为对外汉语教学的一部分。根据不同的教学目的和教学要求,蚕丝文化在对外汉语教学中可尝试3种应用形式:一是作为补充,随文适时扩展,辅助学习者学习语言知识;二是同语言知识学习和语言交际能力培养相结合,开展蚕丝文化主题汉语学习,语言和文化并重;三是作为专门的文化课讲解,开展蚕丝文化专题教学,帮助学习者更深入地了解中国。这些应用形式将有助于传播蚕丝文化,增强国家文化软实力,同时促进对外汉语教学的发展和“一带一路”倡议的实施。

Field investigations and numerical modeling of a giant landslide in the region of Eastern Himalayan Syntaxis:Jiaobunong landslide

Eastern Himalayan Syntaxis(EHS)is a tectonically active region that undergoes continuous geomorphic changes.Large landslides are predominant in this region.A giant landslide called Jiaobunong landslide on the northwestern flank of the EHS were studied and simulated to investigate the formation mechanism,evolutionary process,and failure mechanism of the landside,so that we could better understand the large complex ancient landslides in this region.Field investigation,geological background analyses,and numerical modeling were conducted to reveal the natural and seismic characteristics,as well as dynamic process of the landslide.The results show that the Jiaobunong landslide was the result of long-term geological and geomorphic evolution.Uplift,river incision,weathering,fault creep,glaciation,and earthquakes play key roles in the formation of landslides.Given the huge landslide volume,strong seismicity of the study area,proximity to an active fault,and the need for extra forces to induce landsliding,the Jiaobunong landslide was triggered by a paleo-earthquake.Using numerical simulation based on the discrete element method,the slope dynamic response of the earthquake as well as the mass movement and accumulation process was reproduced.Simulation results showed that the landslide movement experienced four stages:initiation phase(0-5 s),acceleration phase(5-35 s),deceleration phase(35-95 s),and the compaction and self-stabilization stage(after 95 s).The rock mass was disintegrated and experienced strong collisions during the movement.The dammed lake gradually disappeared because of long-term river incision by the overtopping river water.These processes play a vital role in the evolution of landforms in the region of EHS.