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Numerical investigation of friction-heating-pressurization and its control parameters in the shear band of high-speed landslides

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Journal of Mountain Science 2024年第10期21卷 3380-3395页

作者： ZHAO Nenghao CUI Shenghua LU Haijun School of Civil Engineering and Architecture Wuhan Polytechnic UniversityWuhan 430023China state key laboratory of geo-hazard prevention and geo-environment protection Chengdu University of TechnologyChengdu 610059China

High-speed sliding often leads to catastrophic landslides,many of which,in the initial sliding phase before disintegration,experience a friction-induced thermal pressurization effect in the bottom shear band,accelerating the movement of the overlying sliding *** quantitatively investigate this complex multiphysical phenomenon,we established a set of equations that describe the variations in temperature and excess pore pressure within the shear band,as well as the conservation of momentum equation for the overlying sliding *** a simplified landslide model,we investigated the variations of temperature and excess pore pressure within the shear band and their impacts on the velocity of the overlying sliding *** this basis,we studied the impact of seven key parameters on the maximum temperature and excess pore pressure in the shear band,as well as the impact on the velocity of the overlying sliding *** simulation results of the standard model show that the temperature and excess pore pressure in the shear band are significantly higher than those in the adjacent areas,and reach the maximum values in the *** a few seconds after the start,the maximum excess pore pressure in the shear zone is close to the initial stress,and the shear strength loss rate exceeds 90%.The thermal pressurization mechanism significantly increases the velocity of the overlying sliding *** results of parameter sensitivity analysis show that the thermal expansion coefficient has the most significant impact on the temperature and excess pore pressure in the shear band,and the sliding surface dip angle has the most significant impact on the velocity of the overlying sliding *** results of this study are of great significance for clarifying the mechanism of thermal pressurization-induced high-speed sliding.

关键词： High-speed landslide Shear band Friction-heating-pressurization Numerical investigation

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Distribution law and susceptibility of geohazards across a gradient belt of the Western Sichuan Plateau

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Journal of Mountain Science 2024年第6期21卷 1849-1867页

作者： LI Tianbin WANG Jianfeng HE Chaoyang MENG Lubo LI Chaofei MA Junjie WEI Daqiang College of environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China state key laboratory of geohazard prevention and geo-environment protection Chengdu University of TechnologyChengdu 610059China

Across a gradient belt of the Western Sichuan Plateau,geohazards have seriously limited economic and social *** to incomplete statistics,15,673 geohazards have been recorded in the study *** order to mitigate the threat of geohazards to human engineering activities in the region,an overall understanding of the distribution pattern of geohazards and susceptibility assessment are *** this paper,a gradient belt of the Western Sichuan Plateau and its zoning criteria were ***,on the basis of relief amplitude,distance to faults,rainfall,and human activities,three indicators of endogenic process were introduced:Bouguer gravity anomaly gradient,vertical deformation gradient,and horizontal deformation ***,the distribution patterns of geohazards were investigated through mathematical statistics and ArcGIS *** randomly selecting 10,449 hazards,a geohazard susceptibility map was generated using the Information Value(IV)***,the IV model was validated against 5224 hazards using the Area Under Curve(AUC)*** results show that 47.6%of the geohazards were distributed in the zone of steep *** showed strong responses to distance to faults,human activities,and annual *** distribution of geohazards in the gradient belt of the Western Sichuan Plateau is more sensitive to vertical internal dynamics factors(such as vertical deformation gradient and Bouguer gravity anomaly gradient)without any apparent sensitivity to horizontal internal dynamics *** areas of high and very-high risk account for up to 32.22%,mainly distributed in the Longmenshan and Anning River *** to the AUC plot,the success rate of the IV model for generating the susceptibility map is 76%.This susceptibility map and geohazard distribution pattern can provide a reference for geological disaster monitoring,preparation of post-disaster emergency measures,and town planning.

关键词： Gradient belt geohazards Distribution law Bouguer Gravity anomaly gradient Vertical deformation gradient Susceptibility

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Investigating the reactivation of historical landslides during the 2022 Luding M_(S)6.8 earthquake

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Earthquake Science 2024年第3期37卷 200-209页

作者： Tao Wei Mingyao Xia Xinxin Zhang Shaojian Qi state key laboratory of geohazard prevention and geo-environment protection Chengdu University of TechnologyChengdu610059China

On September 5,2022,a strong earthquake with a magnitude of MS6.8 struck Luding County in Sichuan Province,China,triggering thousands of landslides along the Dadu River in the northwest-southeast(NW-SE)*** investigated the reactivation characteristics of historical landslides within the epicentral area of the Luding earthquake to identify the initiation mechanism of earthquake-induced *** of the two newly triggered and historical landslides were analyzed using manual and threshold methods;the spatial distribution of landslides was assessed in relation to topographical and geological factors using remote sensing *** study sheds light on the spatial distribution patterns of landslides,especially those that occur above historical landslide *** results revealed a similarity in the spatial distribution trends between historical landslides and new ones induced by *** landslides tend to be concentrated within a range of 0.2 km from the river and 2 km from the ***,both rivers and faults predominantly influenced the reactivation of historical ***,the reactivated landslides are characterized by their small to medium size and are predominantly situated in historical landslide *** number of reactivated landslides surpassed that of previously documented historical landslides within the study *** provide insights into the critical factors responsible for historical landslides during the 2022 Luding earthquake,thereby enhancing our understanding of the potential implications for future co-seismic hazard assessments and mitigation strategies.

关键词： Luding earthquake co-seismic landslides historical landslides spatial distribution landslide reactivation

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Post-disaster spatial reconstruction from the perspective of a rural settlement niche in the upper reaches of the Minjiang River

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Journal of Mountain Science 2024年第5期21卷 1630-1646页

作者： LIU Yanguo WANG Li ZOU Qiang LI Jingji LU Yafeng LI Lin XU Binni WANG Lihui Tianfu Institute of Research and Innovation Southwest University of Science and TechnologyChengdu 610299China Mianyang Science and Technology City Division the National Remote Sensing Center of ChinaSouthwest University of Science and TechnologyMianyang 621010China Institute of Mountain hazards and environment Chinese Academy of SciencesChengdu 610299China state key laboratory of geo-hazard prevention and geo-environment protection(Chengdu University of Technology) Chengdu 610059China Tianfu New Area Park City Construction Bureau Chengdu Municipal Bureau of Planning and Nature ResourcesChengdu 610218China

Post-disaster recovery and reconstruction provide an effective way to reduce the disaster vulnerability of, and promote leapfrog development in, an affected area. To date, studies that have used administrative boundaries to investigate the reconstruction of settlement space have not been able to clearly define the real boundaries of land use changes or quantify the degree of response to the ‘Build-Back-Better’ initiative, and have lacked any consideration of the fourth reconstruction stage–development period(10 years). This study constructed a mountain settlement niche and analyzed the characteristics, spatial reconstruction, and drivers of rural settlements during 2009–2019 in the upper reaches of the Minjiang River, southwest China. The results showed the following:(1) Natural factors were the basis for the formation and development of mountain settlement niches. The scale of the settlement niche and its land use structure depended on the physical geography features and the ethnic farming and grazing traditions. The settlement niche provided a realistic boundary for the spatial reconstruction.(2) The layout of residential land around cropland was the common feature of the mountain settlement niche. Of all the land use types, the roads and rural residential lands showed the most change over the 10 years;13,860 residential patches increased in size and 4,742 patches were abandoned.(3) The area of orchards, planted to reconstruct the economy in the mountains, increased by nearly 2.5 times.(4) Collapses, landslides, and debris flow disasters and the ecological red line influenced the spatial reconstruction. While the main focus of post-disaster recovery is spatial reconstruction, initiatives should include economic and spiritual recovery, and should also achieve sustainable development of the region.

关键词： Rural settlements Spatial reconstruction Settlement niche Post-Wenchuan Earthquake Reconstruction Southwest China

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Optimal mining sequence for coal faces under a bedding slope:insight from landslide prevention

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Journal of Mountain Science 2024年第5期21卷 1775-1798页

作者： LI Qingmiao ZHAO Jianjun LI Zhichao DENG Jie ZUO Jing LAI Qiyi state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of TechnologyChengdu 610059China

Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.

关键词： Bedding rock landslides Mining-induced deformation Bedding slope stability Underground mining sequences Fractal-based strength reduction method

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Economic Risk Assessment of Future Debris Flows by Machine Learning Method

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International Journal of Disaster Risk Science 2024年第1期15卷 149-164页

作者： Chenchen Qiu Lijun Su Alessandro Pasuto Giulia Bossi Xueyu Geng School of Engineering University of WarwickCoventry CV47ALUK key laboratory of Mountain hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Research Institute for geo-Hydrological protection(IRPI-CNR) National Research Council of ItalyPadova 35127Italy

A reliable economic risk map is critical for effective debris-flow ***,the uncertainties surrounding future scenarios in debris-flow frequency and magnitude restrict its *** estimate the economic risks caused by future debris flows,a machine learning-based method was proposed to generate an economic risk map by multiplying a debris-flow hazard map and an economic vulnerability *** selected the Gyirong Zangbo Basin as the study area because frequent severe debris flows impact the area every *** debris-flow hazard map was developed through the multiplication of the annual probability of spatial impact,temporal probability,and annual *** employed a hybrid machine learning model-certainty factor-genetic algorithm-support vector classification-to calculate ***,a Poisson model was applied for temporal probabilities,while the determination of annual probability of spatial impact relied on statistical ***,four major elements at risk were selected for the generation of an economic loss map:roads,vegetation-covered land,residential buildings,and *** economic loss of elements at risk was calculated based on physical vulnerabilities and their economic ***,we proposed a physical vulnerability matrix for residential buildings,factoring in impact pressure on buildings and their horizontal distance and vertical distance to debrisflow *** this context,an ensemble model(XGBoost) was used to predict debris-flow volumes to calculate impact pressures on *** results show that residential buildings occupy 76.7% of the total economic risk,while roadcovered areas contribute approximately 6.85%.Vegetation-covered land and farmland collectively represent 16.45% of the entire *** findings can provide a scientific support for the effective mitigation of future debris flows.

关键词： Economic risk Future debris fows Gyirong Zangbo Basin Machine learning model Physical vulnerability matrix Southwest Tibet,China

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Creep damage constitutive model of rock based on the mechanisms of crack-initiated damage and extended damage

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Underground Space 2024年第5期18卷 295-313页

作者： Tianbin Li Chao Chen Feng Peng Chunchi Ma Mou Li Yixiang Wang state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of TechnologyChengdu 610059China College of environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China School of Urban Construction Chengdu PolytechnicChengdu 610218China Shudao Investment Group Co. LtdChengdu 610094China

Since the classical element model cannot describe the nonlinear characteristics of rock during the entire compressive creep process,nonlinear elements and creep damage are generally introduced in the model to resolve this ***,several previous studies have reckoned that creep damage in rock only occurs in the accelerated creep stage and is only described by the Weibull ***,the creep damage mechanism of rocks is still not clearly *** this study,a reasonable representation of the damage variables of solid materials is ***,based on the Gurson damage model,the damage state functions reflecting the constant creep stage and accelerated creep stage of rock are ***,the one-dimensional and three-dimensional creep damage constitutive equations of rock are derived by modifying the Nishihara ***,the creep-acoustic emission tests of phyllite under different confining pressures are conducted to examine the creep damage characteristics of *** the proposed constitutive model is verified by analyzing the results of creep tests performed on saturated ***,this study reveals the relationship between the creep characteristics of rocks and the corresponding damage evolution pattern,which bridges the gap between the traditional theory and the quantitative analysis of rock creep and its damage pattern.

关键词： Rock Creep damage Constitutive model Damage state function Indoor tests

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Spatial distribution analysis of landslides triggered by the 2013-04-20 Lushan earthquake,China

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Earthquake Engineering and Engineering Vibration 2016年第1期15卷 163-171页

作者： Chang Ming Tang Chuan Xia Chenhao Fang Qunsheng state key laboratory of geo-hazard prevention and geo-environment protection Chengdu University of Technology

The 2013-04-20 Lushan earthquake（seismic magnitude Ms 7.0 according to the state Seismological Bureau）induced a large number of *** this study,spatial characteristics of landslides are developed by interpreting digital aerial photography *** towns near the epicenter,with an area of about 11.11 km2,were severely affected by the earthquake,and 703 landslides were identified from April 24,2013 aerial photography data over an area of 1.185 *** 55.56% of the landslide area was less than 1000 m2,whereas about 3.23 % was more than 10,000 *** falls and shallow landslides were the most commonly observed types in the study area,and were primarily located in the center of Lushan *** landslide areas were widely distributed near river channels and along *** main factors were chosen to study the distribution characteristics of landslides：elevation,slope gradients,fault,geologic unit and river *** spatial distribution of coseismal landslides is studied statistically using both landslide point density（LPD）,defined as the number of landslides（LS Number）per square kilometer,and landslide area density（LAD）,interpreted as the percentage of landslides area affected by *** results show that both LPD and LAD have strong positive correlations with five main *** landslides occurred in the gradient range of 40°-50° and an elevation range of 1.0-1.5 km above sea *** results also indicate that landslides were mainly formed in soft rocks such as mudstone and sandstone,and concentrated in IX intensity areas.

关键词： Lushan earthquake landslide spatial distribution impact factor

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Revealing the intrinsic mechanisms for accelerating nitrogen removal efficiency in the Anammox reactor by adding Fe(Ⅱ)at low temperature

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Chinese Chemical Letters 2024年第8期35卷 341-348页

作者： Linjing Li Wenlai Xu Jianyong Ning Yaping Zhong Chuyue Zhang Jiane Zuo Zhicheng Pan state key laboratory of geohazard prevention and geoenvironment protection Chengdu University of TechnologyChengdu 610059China state key Joint laboratory of environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China National Postdoctoral Research Station Haitian Water GroupChengdu 610213China National Enterprise Technology Center Haitian Water GroupChengdu 610213China Water Safety and Water Pollution Control Engineering Technology Research Center in Sichuan Province Chengdu 610213China laboratory of Municipal Wastewater Treatment Technology in Sichuan Province Chengdu 610213China Institute of environment and Ecology Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China

Fe(Ⅱ)is an essential trace element for anaerobic ammonium oxidation bacteria(AAOB)metabolism,and can improve the nitrogen removal efficiency of anaerobic ammonia oxidation(Anammox).Here we oper-ated two identical expanded granular sludge bed(EGSB)reactors at low temperature(15±3℃)for 154 *** 1(R_(1))received additional Fe(Ⅱ)(0.12 mmol/L)during the late startup phase,while reactor 0(R_(0))served as the control and did not receive extra Fe(Ⅱ).Nitrogen removal in R_(1)became stable at 55 d of operation,ten days earlier than R_(0).The nitrogen removal rate(NRR)of R_(1) was 1.64 kg N m^(−3)d^(−1)and its TN removal rate was as high as 89%,while R_(0)only reached 75%.The addition of Fe(Ⅱ)was fur-ther beneficial to aggregation and stability of the granular sludge,and the used sludge of both reactors showed enrichment for AAOB populations compared to the inoculum,for instance,increased abundance of Candidatus-Kuenenia and in particular of Candidatus-Brocadia(from 0.17%to 10.10%in R_(0)and 7.79%in R_(1)).Diverse microbial species and complex microbial network structure in R_(1)compared to R_(0)promoted the coupled denitrogenation by Anammox,dissimilatory nitrate reduction to ammonium(DNRA),nitrate-dependent Fe oxidation(NDFO),and ferric ammonium oxidation(Feammox).In addition,the microbial community in R_(1)was more resistant to short-term low temperature(2-7℃)starvation,illustrating a further positive effect of adding Fe(Ⅱ)during the startup phase of an Anammox reactor.

关键词： Ambient low temperature Anammox Fe(Ⅱ) Extracellular polymeric substances Microbial community Microbial network analysis

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laboratory and field evaluation of a low-cost optical particle sizer

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Journal of environmental Sciences 2024年第8期142卷 215-225页

作者： Mingzhen Tang Yicheng Shen Yanzhen Ge Jian Gao Chong Wang Liqing Wu Shuchun Si state key laboratory of environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Jinan Grid-Based Supervision Center of Ecological and environmental protection Jinan 250100China Tai’an Ecological environment protection Control Center Tai’an 271000China School of Physics Shandong UniversityJinan 250013China

Low-cost sensors are widely used to collect high-spatial-resolution particulate matter data that traditional reference monitoring devices *** addition to the mass concentration,the number concentration and size distribution are also fundamental in determining the origin and hazard level of particulate ***,low-cost optical sensors have been improved to establish optical particle sizers(OPSs).In this study,a low-cost OPS,the Nova SDS029,is introduced,and it is evaluated in comparison to two reference instruments—the GRIMM 11-D and the TSI *** first tested the sizing accuracy using polystyrene latex ***,we assessed the mass and number size distribution accuracy in three application scenarios:indoor smoking,ambient air quality,and mobile *** evaluations suggest that the low-cost SDS029 rivals research-grade optical sizers in many *** example,(1)the particle diameters obtained with the SDS029 are close to the reference instruments(usually<10%)in the 0.3-5μm range;(2)the number of particles and mass concentration are highly correlated(r≥0.99)with the values obtained with the reference instruments;and(3)the SDS029 slightly underestimates the number concentration,but the derived PM_(2.5)values are closer to monitoring station than the reference *** successful application of the SDS029 in multiple scenarios suggests that a plausible particle size distribution can be obtained in an easy and cost-efficient *** believe that low-cost OPSs will increasingly be used to map the sources and risk levels of particles at the city scale.

关键词： Optical particle sizer Particle size distribution Low-cost sensor Evaluation Field application

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