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过刊目录

  • 2022年, 19卷, 第11期
    刊出日期：2024-06-19
      
  • 全选
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  • Stability of the Hailuogou glacier during the “9.5” Luding Earthquake: a preliminary assessment based on multi-source observations
    LIU Qiao, ZHANG Bo, ZHAO Bo, ZHONG Yan, LU Xue-yuan, ZHOU Jian-min
    2022, 19(11): 3037-3050.
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    On 5th September 2022, a magnitude Ms-6.8 earthquake occurred nearby Mt. Gongga, western Sichuan. The stability of the glaciers in east Mt.Gongga close to the epicenter was widely concerned due to the strong shake triggered by the earthquake.Using multi-source observations(including in-situ photographs, remote sensing datasets before and after the event), we carried out a preliminary assessment of the stability and hazard risks of the Hailuogou(HLG)glacier. Triggered by the earthquake, a small block of fractured ice at the lowest part of icefall collapsed.The magnitude of the coseismic ice avalanche was relatively small, which is comparable in size to most ice avalanches over the past seven years, but much less than the previous mapped largest one(03 April 2018, runout ～699 m). One most recent large(runout ～608 m) ice avalanche occurred between 01 and 04 September, just before the earthquake, likely unloaded large amount of ice mass and made a larger ice avalanche avoided during the earthquake shake.Nevertheless, the momentum of collapsed snow-icerock mass could be safely unloaded over a wide and gentler-slope ice tongue area, limiting its mobility and the risk of a cascading hazard. Glacier-wide surface flow dynamics monitored by Sentinel-1 satellite SAR time series(12 September 2021 – 19 September 2022)show that HLG glacier velocity was generally consistent before and after the earthquake. The entire HLG glacier exhibited more stable than expected,with almost no abnormal features detected in its upper accumulation part, the lower ice tongue, and its lateral paraglacial slopes. Since the glacier valley has experienced remarkable downwasting and the paraglacial environment has been strongly disturbed and destabilized, we suggested that, to efficiently evaluate glacier-related cascading hazard risks, it is also necessary to systematically combine multi-source observations(e.g., high-resolution UAV survey,radar/Lidar scan, ground investigation, monitoring and warning systems) to continuously monitor the regional glacier anomalies in the post-earthquake seismic active areas.
  • Temperate northern hemisphere dominates the global soil CH_4 sink
    XU Xin, WEI Da, QI Ya-hui, WANG Xiao-dan
    2022, 19(11): 3051-3104.
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    Methane(CH_4) is the second largest longlived greenhouse gas after the CO_2, which contributes 20% of global warming forcing. Global aerated soils remove CH_4 from the troposphere, but the quantification of its magnitude and spatial variability is still of a large uncertainty. This study collected 1240records of the CH_4 uptake by soils across the globe.Our estimates update the global soil CH_4 sink to 31.9+/-0.16 Tg CH_4 a~(-1), 42% higher than the previous inventory-based estimation, with 56% from temperate regions. Also, our dataset revealed that the global drylands dominated the soil CH_4 sink, which is different from traditional forest-dominated view.During the past four decades, the soil porosity affected by soil moisture controls the variation in the uptake in the tropics, while warming temperatures benefit methanotrophs in temperate and boreal soils,especially the drylands, where the soil porosity is not limiting. Our simulations indicate that the CH_4 uptake will increase by 11%–31% by the end of the 21st century, much lower than the previous estimations.This study substantially constrains the global soil CH_4 sink estimates and reveals the warming temperate northern hemisphere is a dominant CH_4 uptake region in the past and future, while the uptake decreases in tropical soils under increasing precipitation.
  • Long-term changes and periodicity of ice phenomena in the high mountain Lake Morskie Oko(Tatra Mountains, Western Carpathians)
    POCIASK-KARTECZKA Joanna, NIECKARZ Zenon, CHOI?SKI Adam
    2022, 19(11): 3063-3075.
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    High montain lakes are regarded as sensitive indicators of environmental changes in local and global scales. In recent years, climate change has considerablely influenced the timing of ice phenomena in these lakes. The objective of the paper is an investigation of long-term changes and periodicity of ice phenomena in high mountain Lake Morskie Oko(1392.8 m a.s.l.) located in the Tatra Mts. in the period 1971-2020. The study employed the Lomb-Scargle periodogram, linear regression modelling for temporal trends, correlation analysis, parameters of variability, and flashiness index. Periodicity of the duration of ice phenomena(～5.4 y) and ice cover on the lake(～13.5 y) was observed, although both are statistically insignificant. Ice cover duration has been interrupted several times by winter thaws after 1996 whereas no such events had been reported earlier. The trend towards a delayed appearance of ice phenomena reaches 4.0 d·decade~(-1)(p < 0.001). The observed trend towards an earlier ice phenomena disappearance reaches 5.1 d·decade~(-1)(p < 0.001). It results in a decline of the number of days with ice phenomena on Lake Morskie Oko at a rate of 9.0 d·decade~(-1)(p < 0.001). The duration of ice cover on Lake Morskie Oko has been decreasing at a rate of 10.4 d·decade~(-1). It is attributed to later freezeup(3.9 d·decade~(-1), p < 0.001) and earlier ice break-up(5.6 d·decade~(-1), p < 0.001). An increasing trend of average annual air temperature(0.4°C·decade~(-1), p < 0.001) in the period 1971-2020 is observed. A statistically significant correlation is recorded between ice phenomena and ice cover(beginning, end, duration), average annual air temperature, average air temperature of three summer months(June, July, August), and average air temperature of the six months period from June to November. Higher air temperature induces growing heat resources accumulated in the lake water in the summer and autumn seasons, potentially causing later initiation of ice phenomena in the lake. There is no statistically significant relationship between maximum ice thickness and any air temperature parameters. Variability of maximum ice thickness appears to have been significantly increasing in the second part of the investigated period(1996-2020).
  • Radiation and energy balance on a hillslope forest: horizontal versus slope-parallel installation of radiometer
    WANG Xing-chang, LIU Fan, WANG Chuan-kuan
    2022, 19(11): 3076-3092.
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    Radiation is a major driver to the carbon,water, and energy exchanges of an ecosystem. For local radiation balance measurements, one essential question is whether the measurement systems should be installed horizontally or parallel to inclined slope surface. With a case study over a temperate deciduous forest on a moderate inclined(9°) northwest-facing slope, we quantified the slope effect on net radiation(Rn) and its components and the energy balance closure measured by an eddy covariance(EC) system.Compared with the slope-parallel radiometer, the horizontal sensor overestimated the incident solar radiation(SR) by 7%, the incoming photosynthetically active radiation(PAR) by 1.5%, and the incoming near-infrared radiation(NIR) by 10%; while underestimated the reflected shortwave radiation(SR)by 4% and NIR by 5%. The influence of radiometerorientation on incoming longwave radiation(LR) was about 3%, while that on outgoing LR was negligible.Summing all these components, horizontal sensor overestimated the Rn by 9%. Converting the horizontally-measured incident radiation to slopesurface reduced a half of the biases on incoming SR and Rn. Measuring the Rn with slope-parallel radiometer and correcting the slope-effect on horizontally-measured incident SR improved the energy balance ratio(EBR) by 8% and 5%,respectively. A mini-review indicated that, the horizontal sensor underestimated(overestimated) the EBR on north-facing(south-facing) slopes in temperate zone in the Northern Hemisphere, with an inclination angular sensitivity of EBR as high as 1.17%per degree of inclination angle. We recommend measuring radiations on inclined terrains with slopeparallel radiometers, or correcting at least for the incident SR in energy balance studies.
  • Effect of gravel content on the detachment of colluvial deposits in Benggang
    ZHANG Li-ting, SHUAI Fang, CHEN Li-bo, HUANG Yan-he, LIN Jin-shi, ZHANG Yue, GE Hong-li, JIANG Fang-shi
    2022, 19(11): 3088-3104.
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    Accurately calculating detachment capacity is the most fundamental issue when establishing a soil erosion process model. Colluvial deposits of Benggang are typical soil-gravel mixtures,whereas the understanding of the soil detachment of colluvial deposits is limited. This work investigated the effects of the gravel contents on the soil detachment capacity of colluvial deposits and its hydrodynamic mechanism. The colluvial sample was collected in Anxi County, Fujian Province, Southeast China, and a small-sample scouring test was used.The slope steepness ranged from 18% to 84%, unit discharge ranged from 0.56×10~(-3) to 2.22×10~(-3) m~2 s~(-1),and gravel content ranged from 0% to 70%. The results indicated that the gravel content is the primary factor that influences the detachment capacity,followed by the discharge and then the slope. The detachment capacity trend with the gravel content varied over different slopes and discharges. Stream power represents the best hydrodynamic parameter for modelling the detachment capacity of colluvial deposits and can be used to establish a fitting equation for the colluvium together with the mean weight diameter(MWD)(Nash-Sutcliffe efficiency(NSE)=0.96). As the gravel content increased, the soil erodibility parameters increased several folds, in some cases more than 10 folds, mainly because the soil shear strength decreased gradually. Meanwhile,as the gravel content increased, the gravel specific surface area increased, the obstruction of gravel to runoff increased, and the energy needed for runoff to overcome gravel obstruction increased, leading to 2-3 folds higher critical shear stress of runoff for soilgravel mixtures compared with pure soil. In summary,gravel can influence the detachment capacity by changing the soil properties, and the gravel content also affects the relationship between soil detachment capacity and the hydrodynamic parameters. These findings deepen the understanding of the influence of gravel on soil erosion and provide a basis for establishing a soil erosion process model in colluvial deposits.
  • Reconstruction of surface deformation characteristics in alpine canyons under shadow conditions
    GU Zhen-kui, YAO Xin
    2022, 19(11): 3105-3117.
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    Monitoring deformation in high undulating mountainous environments is critical for surface process research and disaster prevention studies. Although observations based on interferometric Synthetic Aperture Radar(InSAR) are an excellent tool for monitoring deformation, the shadow phenomena can limit its application. Based on a series of geomorphic parameters and limited InSAR observation data, surface deformations were reconstructed in areas with missing observations by constructing a random forest model to compensate for the shadow phenomenon at the grid-scale. The findings suggest that this method can be used to rebuild landscape variation characteristics in places where observation data is lacking. The dominant slope direction in the observation area corresponded to a more significant correlation between the reconstructed topography deformation characteristics and the observation. In addition, when building this model, consideration was given to the geomorphic parameter selection, elevation variation, hypsometric integral value, slope form, lithology, slope variation,and aspect variation; these parameters can significantly affect the surface deformation, which is closely related to their spatial autocorrelation. These findings are significant for eliminating the shadow phenomenon, which often occurs in In SAR observations taken over alpine canyon regions. The terrain and lithology of the underlying surface should be considered when reconstructing the surface deformation characteristics of the shadow region by using satellite observation data.
  • Effects of rainfall and rocky desertification on soil erosion in karst area of Southwest China
    PAN Li-dong, LI Rui, SHU Dong-cai, ZHAO Li-na, CHEN Mei, JING Jun
    2022, 19(11): 3118-3130.
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    Monitoring and evaluating the evolution of rocky desertification timely and studying the characteristics of soil erosion under different rainfall patterns are of great scientific significance for regional soil and water conservation, rocky desertification control and ecological environment construction. Four periods of remote sensing image data from 2005 to 2020 were selected to study the evolution characteristics of rocky desertification and its impact on soil erosion in the controlled boundary area of Shibantang hydrological station of Yeji River Watershed, Guizhou Province, China. According to the 408 erosive rainfall events, the soil erosion under different rainfall patterns in the watershed was analyzed. The results showed that: erosive rainfall events in the study area were mainly pattern A,accounting for 57.4% of the total rainfall events; the second was pattern B, accounting for 28.9% of the total rainfall events; the rainfall pattern of C occurred occasionally. Among them, pattern A was the main rainfall pattern leading to soil and water loss and had the largest contribution rate to soil erosion in the watershed. From 2005 to 2020, the area of rocky desertification showed a decreasing trend, accounting for 72.2% from 87.9%. Spatially, rocky desertification has mainly concentrated in the middle south of the watershed since 2010, while the rocky desertification mainly concentrated in the middle and north before 2010. The effects of different grades of rocky desertification on soil erosion were different, and the soil erosion modulus in areas with the medium,severe and extremely severe rocky desertification was generally small. The soil erosion modulus estimated by the RUSLE(Revised Universal Soil Loss Equation)model was still much higher than that calculated by the data measured by the hydrological monitoring station. Therefore, the application of the RUSLE model in karst area needs to be further modified.These results can provide reference for rocky desertification control, soil erosion control and fragile ecosystem restoration in karst area.
  • Vegetation recovery trends under dual dominance of climate change and anthropogenic factors in the severely damaged areas of the Wenchuan earthquake
    WANG Qian, WANG Ze-gen, YONG Zhi-wei, ZHAO Kai, XIONG Jun-nan, DU Xue-mei, Zhao Yang
    2022, 19(11): 3131-3151.
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    The occurrence of the Wenchuan earthquake caused the degradation of regional ecosystems, including vegetation destruction.However, the post-seismic vegetation recovery and its driving forces on the spatial-temporal scale are still vague, especially in the severely damaged areas(including Wenchuan, Beichuan, Mianzhu, Shifang,Qingchuan, Maoxian, Anzhou, Dujiangyan, Pingwu and Pengzhou). Here, we detected vegetation recovery in the severely damaged areas by using Ensemble Empirical Mode Decomposition(EEMD) to analyze the time series characteristics of the Enhanced Vegetation Index(EVI), and explored the driving effects of climate, land use types, nighttime light,water system, slope, and clay content on vegetation recovery based on Geographically and Temporally Weighted Regression(GTWR) model. The results indicated that the post-seismic vegetation recovery rate increased rapidly(acceleration > 0) but slowed down after 2013. And the areas of best vegetation recovery(EVI increments > 0.1) were distributed in the north of the study area, the Minjiang River Basin,and front fault and central fault of the Longmenshan Fault Zone. While the areas with the worst vegetation recovery(EVI increments <-0.1) were concentrated in the southern high-altitude areas and the Chengdu Plain. Additionally, a process attribution of the driving forces of vegetation recovery indicated that accumulated precipitation and maximum temperature promoted vegetation recovery(regression coefficients > 0), but the impacts weakened after the earthquake, possibly due to the increase of secondary disasters induced by precipitation and the rise in maximum temperature.The impact of cultivated land on vegetation recovery was mostly positive(regression coefficients > 0),which may be related to the implementation of the Grain for Green Project. The nighttime light inhibited vegetation recovery(regression coefficients < 0),which could be closely associated with urbanization.The results indicated that more attention should be paid to the nonlinear variations of post-earthquake vegetation recovery trends, and the effects of climatic and anthropogenic factors on vegetation recovery also should not be underestimated.
  • Seismotectonics of Southern Calabria Terrane(South Italy)
    Vincenzo TRIPODI, Anna GERVASI, Mario LA ROCCA, Federica LUCà, Francesco MUTO
    2022, 19(11): 3148-3162.
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    Seismic data of earthquakes recorded during the last 40 years in southern Calabria have been compared with geological data in order to obtain a seismotectonic picture of the area. We sought for any possible correlation between the main regional tectonic structures, the distribution of earthquake hypocentres and the focal mechanism of earthquakes with magnitude(Ml)≥3.Studies of historical and recent seismicity and analysis of geological structures allowed to define the main shear strips on a regional scale. More than 2600 earthquakes with 1.5 ≤ Ml ≤ 4.5 have been considered. The focal mechanisms of earthquakes with Ml≥3 have been compared with the kinematics of known faults and used to give insight on the current active stress field. From the analysis carried out it was possible to expand the cognitive framework regarding the activity of the main tectonic structures present in the area. This study also served to identify areas of high seismicity which do not correspond to any evidence of tectonic structures on the surface, and areas where recognized tectonic structures have not shown any seismicity during the last decades. These cases could be the subject of future investigation in order to correctly assess the seismic hazard in Calabria.This task is important in the context of seismic hazard evaluation and mitigation.
  • Long-term reconstruction of flash floods in the Qilian Mountains, China,based on dendrogeomorphic methods
    QIE Jia-zhi, ZHANG Yong, TRAPPMANN Daniel, ZHONG Yi-hua, BALLESTEROS-CáNOVAS Juan Antonio, FAVILLIER Adrien, STOFFEL Markus
    2022, 19(11): 3163-3177.
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    In China, flash floods are one of the main natural disasters causing loss of life and damage to infrastructure. The threat of flash floods is exacerbated with climate change and increased human activities, such that the number of disasters has shown a clear upward trend in recent years.However, due to the scarcity of instrumental data or overly short timeseries, we are still lacking critical data to understand spatio-temporal patterns and driving factors of extreme flash floods. This missing knowledge is however crucial for a proper management of these hazards, especially in remote mountain environments. In forested catchments,dendrogeomorphology allows the reconstruction of past process activity based on growth disturbances(GDs) in trees that have been affected by past flash floods. Therefore, in our study, for the first time, we reconstruct past flash floods in the Qilian Mountains,northeast Tibetan Plateau, over past centuries. To this end, we sampled 99 Qinghai spruce(Picea crassifolia)trees affected by flash floods, with a total of 194increment cores, and identified 302 GDs induced by past flash floods. These GDs have been caused by at least 21 flash floods that we are able to reconstruct over the last 170 years. The position of GDs within tree rings and the intra-seasonal dating of past events also allowed discussion of the likely synoptic situations that may have led to the triggering of flash floods in the past. Logistic regression analysis confirms that significant correlation exists between cumulative maximum 5-day August-September precipitation and reconstructed flash floods, which is corresponding to the majority of scars and related tangential rows of traumatic resin ducts(TRDs) found in the latewood portion of growth rings. These results support the idea that abundant precipitation occurring at the end of the summer season and early fall is the key factor driving flash floods in our study area. Our research not only fills the gaps regarding historical flash flood histories in the Qilian Mountains,but also provides a scientific basis for the region's response to climate change and flood prevention and reduction.
  • Medical transportation and the contribution of air medical evacuation in isolated mountainous areas of Greece-Case study, Municipality of Agrafa
    Ioanna KARANI, Anastasios BALASKAS, Dimitris KALIAMPAKOS
    2022, 19(11): 3178-3191.
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    In every emergency medical situation,access to emergency medical services is an inalienable right of any citizen. The average acceptable time to provide first aid assistance is 60 minutes. In this paper, the possibility of using helicopters for air travel in mountainous areas was examined for the first time for all of Greece and especially for a mountainous and isolated area such as the Municipality of Agrafa.Initially, the time distance-virtual distance, from the hospitals was calculated at the national level of Greece,with an acceptable first contact time of 60 minutes(golden hour), i.e., less than two hours from the nearest hospital to the incident and back to the hospital and the relevant conclusions are drawn. Then,the case study of Municipality of Agrafa, one of the most mountainous areas in Greece, was examined.The time distance of the settlements from the nearest primary health point, namely the Primary Health Centre(PHC) of West Fragkista, was calculated and the transportation by ground means was compared with the corresponding time by flying means, to investigate the contribution of air transportation or not, of the timely arrival of the patients in the appropriate health structure. Finally, possible helicopter landing locations were identified, using a geographic information system to facilitate the process of air medical transportation in the Municipality of Agrafa.
  • Granitic inselbergs of Lara(Panafrican Chain, Far-North Cameroon): Assets for the implementation of geotourism in Mountainous region
    ZANGMO TEFOGOUM Ghislain, NOUHOU DAMA Zouyane Hyacinthe, GOUNTIé DEDZO Merlin, MAFO DONGMO Irène
    2022, 19(11): 3192-3212.
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    The locality of Lara(Far-North Region,Cameroon) is made up of a pediplain strewn with coalescent plutons. The interaction of internal and external geological processes has contributed to transform the latter into inselbergs, whose geotouristic values are yet to be studied. Field and laboratory work enabled us to select the geomorphosites through their aesthetic value(particular size and shape) and, geomorphological and geological features. Moreover, it permitted to study and map the geomorphosites using Optic Microscope, Google Earth, GIS software and many other interfaces. Hence, four inselbergs have been selected and studied in the locality of Lara. The petrographic study of these inselbergs shows that granites are the main components of inselbergs and they present a fine to coarse-grained texture,materialized by quartz, micas, plagioclases and alkali feldspars(white and pink in colour). Inselbergs exhibit vertical and parallel networks of diaclases giving them a stratified appearance in some flanks. In addition, on some inselberg limbs and piedmonts, are built tors which contribute to their beauty. The tops of inselbergs, are embellished by several alluring pedestal rocks. On their flanks, shelters of various shapes and sizes(about 12 m length) have developed through the heaps of blocks field. Among the ten shelters selected, some have a fairly high cultural value as they are sacred places for the local population.Moreover, Lara's granitic inselbergs include enclaves(cognate enclaves and xenocrysts) that also significantly improve their geoheritage value.Inselbergs are landforms with high education and aesthetic value that attracted a larger local and foreign population of about 863 visitors between 2017-2019.They constitute an exceptional geoheritage that could attract more tourists in the locality of Lara; but the promotion of geotourism is needed through interpretative panels, marketing of geomorphosites through leaflets, web, media, and geotours, to mention a few.
  • Spatial identification of poverty in mountainous cities based on the mountain poverty spatial index: A case study of Ganzhou city in 2018 in China
    WANG Jin-liang, CUI Zhi-chao, ZHOU Bing-juan
    2022, 19(11): 3213-3226.
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    Poverty is a severe barrier to sustainable human development and a pressing worldwide issue.Understanding how to accurately assess the spatial distribution of poverty in mountain areas has become crucial for ensuring that governments at all levels take suitable poverty reduction strategies. In this study,the mountain poverty spatial index(MPSI) was created by combining the digital elevation model(DEM), Luojia-1 night-time light imagery, point of interest(POI) data, and vegetation index products.The MPSI was then used to identify the spatial characteristics of poverty at different scales in the hilly area of Ganzhou city, Jiangxi Province, China.Socioeconomic statistics and Google satellite images were used to verify the reliability of MPSI by constructing a multidimensional poverty index(MPI)at the county scale. The results showed that MPSI and MPI have a positive correlation with a correlation coefficient of 0.8934(P<0.001), which indicates that MPSI could be used to identify the spatial distribution of poverty well. Specifically, the smallest distribution of both MPSI and MPI was in Zhanggong District(1.4555 and 0.1894), which indicates that most of the affluent counties were concentrated in the central region of Ganzhou, and the poor areas were scattered in the surrounding areas of Ganzhou. In addition,MPSI accurately identified poverty in mountainous areas with complex terrain in small administrative units, which can provide a more accurate way to monitor the poverty situation in the mountainous areas of China. This study will be useful for providing scientific references for the Chinese government to implement targeted strategies for eradicating poverty with differentiated policies.
  • What are the keys to influence the life satisfaction of eco-migrants in the northern foot of the Qilian Mountains? A test based on the livelihood risk interaction
    WANG Ya, ZHOU Li-hua
    2022, 19(11): 3227-3248.
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    Eco-migrants' ability to adapt to livelihood risks and their satisfaction with lives directly affect the ecological and economic benefits of ecological migration engineering. To formulate an effective livelihood risk prevention system and welfare guarantee mechanism, we took the ecomigrants in Wuwei City as an example, developed an integrated analytical framework for life satisfaction and employed linear regression models to identify the interactions between livelihood risk and life satisfaction. Our findings indicate that 94.66% of eco-migrants in Wuwei City are threatened by livelihood risks after relocation. High living expenses,poor quality of redistributed production goods, and re-poverty constitute the main risks. The risk multiplicity index is 2.96. Besides cultural types,there are no significant differences in regions and livelihoods. A total of 55.73% of eco-migrants are satisfied with their lives, with the Liangzhou district scoring the highest. Except for satisfaction with development potential and public services, no significant intergroup differences were found among regions and livelihood patterns. Eco-migrant's life satisfaction is significantly affected by livelihood risks. Eco-migrants' satisfaction with living income,social integration, farmer-friendly policies and overall life is negatively affected by the risk of repoverty and inadequate social security. An ecomigrant's satisfaction with development potential and community construction is not influenced by one type of risk alone, but the interaction between risks has a strong influence. The interaction of welfare risks with economic risks and policy risks will balance and weaken the adverse effects of a single risk on those elements in the economic and policy spheres. This study offers novel ideas for rural revitalization, hollow governance, and well-being assurance.
  • Effects of stand types on recreational preferences of society in the Sub-Alpine Zone, northern Turkey
    Tu?rul VAROL, Halil Bar?? ?ZEL, Ferhat KARA, ?lkim ?AVU? KARA, Sezgin AYAN
    2022, 19(11): 3246-3256.
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    The main objective of this study was to examine how different stand types influenced the tendency of visitors for varying recreational activities(i.e., hiking, trekking, camping and hunting) from 1993 to 2018 in the surrounding areas of Uluyayla Natural Recreation Site in Bart1n, northern Turkey. A total of 627 visitors were selected on a voluntary basis,and questioned in the form of questionnaire. Most of the participants were in the age of 21-40 years old,and they were mostly(62.4%) male. Most of the participants(82.7%) lived in cities, while 62.8% of them were tourists when visiting the site. In determining the preferences of the visitors regarding the stand types for different recreational activities,several images of each stand were shared with them,and they were asked which stand type they would prefer for a given recreation activity(i.e., hiking,tracking, camping and hunting). A range of options from 1 to 5 in Likert's scale was used in evaluating the given responses. The degree of positive and negative effects was examined via trend analysis. It was found that stand type had influence on the preferences of visitors regarding the recreational activities. In general, unmanaged and moderately treated stands were more preferred by visitors for the recreational purposes, compared to the previously managed stands. On the other hand, visitors' preference for the activities were different during two periods(i.e., 1993-2005 and 2006-2018). For each recreational activity,there was an increasing trend from 1993 to 2018.There had been a continuous increase for hunting since 1996, and for trekking and camping after 1999.The increases between 1993-1996 and 1996-1999 were likely due to the increasing awareness of the society as a result of the training and consciousness raising activities for nature conservation. The demand on the recreational activities continuously increased in unmanaged and moderately treated stands, while no significant changes were examined in the previously managed stands. The study points out that forest planning and management should consider different needs of visitors for recreational infrastructure.
  • Analysis of blasting vibration signal of high steep anti-dip layered rock slope
    SUN Xiao-ming, PANG Shi-hui, QIN Ke, SHI Ting-ting, ZHU Chun, TAO Zhi-gang
    2022, 19(11): 3257-3269.
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    Blasting is one of the most economical and efficient mining methods in open-pit mine production.However, behind the huge benefits, it poses a hidden threat to the quality of slope rock mass, stability of slope, and safety of nearby buildings. In order to explore the influence of blasting vibration on the stability of anti-dip layered rock slopes, herein, the site near the large-scale toppling failure area of Changshanhao gold mine stope of Inner Mongolia Taiping Mining Co., Ltd. was selected for on-site blasting test and monitoring. The Peak Particle Velocity(PPV) measured at the monitoring point is located on the lower side of the maximum allowable vibration velocity curve that is prepared based on the allowable speed standard evaluation chart in the full frequency domain established by standards practiced in various countries such as German DIN4150, the USBM RI 8507, and Chinese GB6722-2014. This indicates that the blasting vibration has less influence on the location of the monitoring point. The vibration signals obtained in the blasting test were analyzed using the wavelet packet theory, and it was concluded that the blasting vibration signals measured in the anti-dip layered rock slope were mainly concentrated in two frequency bands of 0-80 Hz and 115-160 Hz.The sum of energy of the two frequency bands accounted for more than 99%, wherein, the energy contained in the 0-80 Hz frequency band accounted for more than 85% of the monitoring signals. The vibration signal with 0-80 Hz frequency band monitored at the slope toe was selected for the energy attenuation analysis. The results showed that the energy attenuation decreased in radial, vertical, and tangential directions. Further, the Energy Attenuation Rate per Meter(EARPM) was calculated. In conjunction with the site characteristics analysis, it was found that the energy attenuation rate was significantly affected by the rock mass characteristics of the structural plane. The slope reinforcement project can effectively reduce the absorption of vibration energy by the slope and increase slope stability.
  • Numerical analysis of pile–slope stability and the soil arching around two adjacent piles
    Chien-Yuan CHEN, Chun-Kai CHANG, Yu-Shan LIN
    2022, 19(11): 3270-3285.
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    Seismic pile–slope stability analysis and the formation mechanism of soil arching have not been well studied. This study used a threedimensional(3D) finite difference to determine soil and pile parameter changes in the static and seismic stability of the pile–slope caused by the interaction between stabilizing piles. Pile–slope stability analysis was performed to determine the optimal design of piles along a slope and the corresponding failure mode involving the formation of soil arching around two adjacent piles. The Factor of Safety(FS) of the slope was evaluated using the shear strength reduction method for static and seismic analyses. The results of the analysis show that suitable pile spacing(S) and a suitable pile diameter(D) in the middle of a slope result in the maximum FS for the pile–slope system and the formation of soil arching around two adjacent piles. FS of the pile–slope increased negligibly in the seismic analysis of piles located at the slope crest and toe. An optimized pile diameter and installation location afforded the maximum FS for the slope that corresponded to a specified slope failure mode for different pile locations. A pile spacing S ≤ 2.5D for piles installed in the middle of the slope is suggested for increasing the static and seismic pile–slope stability.
  • Stress analysis of full-length grouted bolt under shear deformation of anchor interface
    ZHU Zheng-de, SHU Xiao-yun, LI Zhe, TIAN Hong-ming, TIAN Yun
    2022, 19(11): 3286-3301.
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    The bolt anchoring force is closely related to the shear properties of the anchor interface. The shear stress distribution of full-length grouted bolts is analyzed based on the stress-strain relationship among the bolt, grout, rock mass and bond interface,considering the shear properties of the grout and contact interface bonding behavior. In this case, the interfacial shear stress of the grout and rock mass and the bolt axial force are obtained under pull-out and normal working conditions. The results show that the peak shear stress of the interface with the shear deformation of the bond interface is significantly lower than that without it when the pull-out force is applied. When designing bolt parameters of grade IV and V rock mass, the relative deformation between the rock mass and anchor should be considered, with a “unimodal” to “bimodal” shear stress distribution.In the case of a low elastic modulus of rock masses,both the shear stress concentration and distribution range are obvious, and the neutral point is near the bolt head. As the elastic modulus increases, the shear stress concentration and distribution range are reduced, and the neutral point moves towards the distal end. As a result, the optimum length of fulllength grouted bolts can be determined by in-situ pull-out tests and decreases with the increased elastic modulus of the rock mass.
  • A new numerical model of ring shear tester for shear band soil considering friction-induced thermal pressurization
    ZHAO Neng-hao, SONG Kun, ZHANG Rong-tang, YI Qing-lin
    2022, 19(11): 3302-3313.
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    In this study, a new numerical model of ring shear tester for shear band soil of landslide was established. The special feature of this model is that it considers the mechanism of friction-induced thermal pressurization, which is potentially an important cause of high-speed catastrophic landslides. The key to the construction of this numerical ring shear model is to realize the THM(thermo-hydro-mechanical)dynamic coupling of soil particles, which includes the processes of frictional heating, thermal pressurization,and strength softening during shearing of solid particles. All of these are completed by using discrete element method. Based on this new model, the characteristics of shear stress change with shear displacement, as well as the variation of temperature and pore pressure in the specimen, are studied at shear rates of 0.055 m/s, 0.06 m/s, 0.109 m/s and 1.09 m/s, respectively. The results show that the peak strength and residual strength of specimen are significantly reduced when the mechanism of frictioninduced thermal pressurization is considered. The greater the shear rate is, the higher the temperature as well as the pore pressure is. The effect of shear rate on the shear strength is bidirectional. The simulation results demonstrate that this model can effectively simulate the mechanism of friction-induced thermal pressurization of shear band soil during ring shear process, and the shear strength softening in the process. The new numerical ring shear model established in this study is of great significance for studying the dynamic mechanism of high-speed catastrophic landslides.
  • Boundary effect of toppling failure based on three-dimensional mechanical model
    CAI Jun-chao, ZHENG Da, JU Neng-pan, HUANG Run-qiu, ZHAO Wei-hua
    2022, 19(11): 3314-3322.
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    Previous researches on the mechanical model of toppling failure mainly concentrated on twodimensional mechanical model(TwDM) analysis. The TwDM analysis assumes the width of the slab beam is unit width without considering the lateral constraint force. The assumed conditions are obviously different from the site conditions, thus there is a certain difference between the calculated results and the field work. A three-dimensional mechanical model(ThDM)of toppling failure was established, considering that the slab beam was mainly subject to self-weight, the frictional resistance of interlayer and lateral constraint force. Due to the progressive characteristics of toppling failure, the concept and the formula of the first fracture depth(FFD) of toppling was raised and constructed. The case study indicates that the ThDM is more effective and can be accurately used to calculate the toppling fracture depth of the slab beam. The FFD decreases proportionally with the increase of slab beam width. FFD grows fast when the slab beam width is less than 2.0 m and it tends to be stable when the slab beam width is above 2.0 m. The FFD decreases with the increase of the lateral constraint coefficient, indicating that the boundary condition of the free space is positively correlated with the stability and depth of toppling. This is a good explanation of the free space effect. This study provides a reference for the stability evaluation and prevention-control design of toppling slope in the future.