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过刊目录

  • 2023年, 20卷, 第02期
    刊出日期：2024-06-19
      
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  • Altitude as environmental filtering influencing phylogenetic diversity and species richness of plants in tropical mountains
    GALVáN-CISNEROS Carlos M., VILLA Pedro M., COELHO Alex J.P., CAMPOS Prímula V., MEIRA-NETO Jo?o A.A.
    2023, 20(02): 285-298.
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    Elucidating how multiple factors affect biodiversity and plant community assembly is a central issue in ecology, especially in vulnerable ecosystems such as tropical mountains. These studies are more relevant in global warming scenarios that induce the upward displacement of plant species towards reduced habitats and hostile environments in tropical mountains. This study aimed to analyze how altitude affects taxonomic and phylogenetic diversity in plant communities of tropical mountains. Thus, we tested if(i) increased altitude works as an environmental filtering promoting decreased species richness, decreased phylogenetic diversity, and increased phylogenetic clustering in these tropical mountains; and if(ii) plant communities of high altitude in tropical mountains are also result of recent diversification with plant species recently split shortening phylogenetic distances between closest related species. We tested effects of altitude on species richness and phylogenetic metrics using linear mixed-effects models. Mount Haleakala presented 114species, Mount Kilimanjaro presented 231 species and Mount Purace presented 280 species. We found an environmental filtering effect with increasing altitude causing phylogenetic clustering,decreased phylogenetic diversity and decreased species richness.The decreasing phylogenetic distances between closest relatives are congruent with neo-endemics,suggesting recent plant diversification in high altitudes of tropical mountains, possibly driven by geographic isolation and environmental heterogeneity.Consequences of global warming should be monitored in tropical mountains focusing on distribution shifts.
  • Half-a-century(1971–2020) of glacier shrinkage and climatic variability in the Bhaga basin, western Himalaya
    DAS Suresh, SHARMA Milap Chand, MURARI Madhav Krishna, NüSSER Marcus, SCHMIDT Susanne
    2023, 20(02): 299-324.
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    Glacier shrinkage is a globally occurring phenomena.High-resolution change detection based on frequent mapping and monitoring of high-altitude glaciers is necessary to precisely evaluate future water availability and to understand glacier evolution under different climatic scenarios in the HindukushKarakoram-Himalayan(HKH) region.This also holds true for the Bhaga basin of the western Himalaya.This study investigates glacier and glacier lake changes in the Bhaga basin,over the last five decades based on satellite imagery including Corona KH4(1971),Landsat 7 Enhanced Thematic Mapper Plus(ETM+;2000),Linear Imaging Self-Scanning Sensor(LISS Ⅳ;2013),and Sentinel 2(2020).Regional temperature and precipitation trends were evaluated from gridded climatic datasets(1900-2020).In the Bhaga basin 306 glaciers(>0.2 km~2) were mapped with a total area of 360.3±4.0 km~2,of which 55.7±0.6 km~2 was covered with debris in 2013.The total glacier covered area decreased by ～8.2±1.5 %(0.16±0.03 % yr~(-1)) during the entire observation period1971-2020,with noticeable heterogeneity between tributary watersheds.In the past two decades(2000-2020),the deglaciation rate has increased significantly(0.25 % yr~(-1)) compared to the previous decades(1971-2000;0.12 % yr~(-1)).Glacier lake area increased by 0.6±0.1 km~2(0.012 km~2 yr~(-1)) between1971 and 2020.The NCEP/NCAR climatic data reveals an increase of 0.63℃ in temperature and a decrease of 6.39 mm in precipitation for the period1948-2018.In comparison,APHRODITE data shows an increasing trend in temperature of 1.14℃ between1961 and 2015 and decreasing trend in precipitation of 31 mm between 1951 and 2007.Both NCEP/NCAR and APHRODITE data reveal significant temperature increase and precipitation decrease since the 1990s,which have probably augmented ice loss in the Bhaga basin during the early 21~(st) century.
  • Late Holocene glacier variations indicated by the δ~(18)O of ice core enclosed gaseous oxygen in the central Tibetan Plateau
    LI Jiu-le, XU Bai-qing, WANG Ning-lian, YAO Ping, XU Xiang-ke
    2023, 20(02): 325-337.
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    The δ~(18)O of ice core enclosed gaseous oxygen(δ~(18)Obub) has been widely used for climate reconstruction in polar regions. Yet, less is known about its climatic implication in the mountainous glaciers as the lack of continuous record. Here, we present a long-term, continuous δ~(18)Obub record from the Tanggula glacier in the central Tibetan Plateau(TP). Based on comparisons of its variation with regional climate and glacier changes, we found that there was a good correlation between the variation of the δ~(18)Obub in this alpine ice core and the accumulation and melting of this glacier. The more developed the firn layer on glacier surface, the more positive the δ~(18)Obub. Conversely, the more intense the glacier melting, the more negative the δ~(18)Obub.Combined with the chronology of ice core enclosed gases, the glacier variations since the late Holocene in the central TP were reconstructed. The result showed that there were four accumulation and three deficit periods of glaciers in this region. The strongest glacier accumulation period was 1610-300 B.C., which corresponds to the Neoglaciation. The most significant melting period was the last 100 years,which corresponds to the recent global warming. The Medieval Warm Period was relatively significant in the central TP. However, during the Little Ice Age,there was no significant glacier accumulation in the central TP, and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.
  • Bedrock outcropping in the accumulation zone of the largest glacier in Mexico(Glaciar Norte of Citlaltépetl), as evidence of a possible accelerated extinction
    SOTO Víctor
    2023, 20(02): 338-354.
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    The highest volcano in Mexico, at the same time the third largest mountain in North America(Citlaltépetl, 5610 m a.s.l.), is home to the largest glacier in the country. Because of the extinction of the Popocatépetl glacier(5500 m a.s.l.) caused by eruptive activity, and the almost disappearance of the Iztaccíhuatl glaciers(5220 m a.s.l.) due to the lower elevation of the mountain, the Glaciar Norte of Citlatépetl has been the only glacier that has shown a certain degree of stability as a response to the altitude in which it is located. However, as occurs in almost all glaciers on the planet, the retreat of its glacier terminus has been continuous. Furthermore, during the last years the thickness of its upper part began to decrease rapidly until its bedrock was exposed for the first time in 2019. Due to its ecosystem importance and because it is the main glacier in Mexico, as well as the only one in the world located at latitude 19°N, in this work its current dimensions are updated, as well as the local climatology that governs the current state of the glacier is pointed out. The study was based on the analysis of high-resolution Sentinel-2 optical images, as well as through Sentinel-1 SAR images,with the support of climatological information from the study area. Therefore, the outcropping of the bedrock in the accumulation zone and the consequent horizontal retreat of the upper part of the glacier are documented; at the same time, the decrease in the thickness of the ice along it is noted. The rocky outcrop in the accumulation zone suggests that the flow dynamics of the ice towards the ablation zone will be considerably less, accelerating the retreat of the glacier terminus. Finally, the ascent of the glacial front to 5102 m a.s.l. and the modelled altitude of the equilibrium line to 5276 m a.s.l. are reported as a warning signal in terms of snow catchment and mass balance; likewise, the decrease of 23% of its surface is also indicated regarding the surface reduction monitoring that has been done until 2017. These findings may indicate that the future of this glacier is related to its possible extinction sooner than previously thought, with severe environmental consequences, especially in terms of the provision of drinking water for thousands of inhabitants of the slopes of the volcano. This research is expected to help reflect on the impacts of current climate variability and at the same time serve as a reference for the tropical glaciers on the planet.
  • Variation of soil-plant-atmosphere continuum stable isotope and water source in Qinghai spruce forest of the eastern Qilian Mountains
    ZHOU Jun-ju, WANG Xue, MA Luo, LUO Chu-yu, TANG Hai-tao, GUO Zhao-nan, CHEN Jia-wei, SHI Su-han, SHI Wei, WEI Wei, ZHANG Dong-xia, LIU Chun-fang
    2023, 20(02): 355-366.
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    Understanding the hydrogen and oxygen stable isotope composition and characteristics of different water bodies in soil-plant-atmosphere continuum is of significance for revealing regional hydrological processes and water cycle mechanisms.In this study, we analyzed the stable isotopic composition, relationship and indicative significance of precipitation, soil water(0～100 cm depth) and xylem water of Qinghai spruce(Picea crassifolia)forest in the eastern Qilian Mountains, and explored the circulation process among different water bodies.The results show that the stable isotopes of precipitation vary greatly during the entire observation period. The values of δ~2H and δ~(18)O in the precipitation in the warm season are richer than those in the cold season, and the slope and intercept of local meteoric water line(LMWL, δ~2H = 6.79δ~(18)O+7.13) are both smaller than global meteoric water line(GMWL,δ~2H=8.17δ~(18)O+10.56). The stable isotopes of soil water at different depths underwent different degrees of evaporative fractionation, and the δ~(18)O and δ~2H of shallow soil water varied greatly, while the deep soil water tended to be similar. The topsoil(0～10 cm) can respond quickly to precipitation, and the response of the deep soil has a time lag. In the whole growing season, 0～30 cm and 60～100 cm soil water are the main water sources of Qinghai spruce. The water source of Qinghai spruce was from all soil layers in May and September, mainly from the shallow soil layer(0～30 cm) in August and October, and mainly from the deep soil layer(60～100 cm) in June and July.
  • Estimation of soil erosion and sediment yield in Wadi El Hachem watershed(Algeria) using the RUSLE-SDR approach
    SAOUD Mohammed, MEDDI Mohamed
    2023, 20(02): 367-380.
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    One of the most common types of soil degradation is water erosion. It reduces soil quality at the erosion site and may cause sedimentation issues at the deposition site. This phenomenon is estimated using a variety of models. The Revised Universal Soil Loss Equation(RUSLE) model is the most often used,due to its consistence and low data requirement. It is useful for estimating annual soil loss at the watershed scale. To investigate the relationship between soil erosion and sediment deposition, the combined RUSLE and Sediment Delivery Ratio(SDR) models are used. The Wadi El Hachem watershed is a coastal and mountainous Mediterranean basin with rugged topography and high degree of climatic aggressiveness. Both of these characteristics can have an immediate effect on soil erosion and sediment yield. This research includes estimating the Average Annual Soil Loss(A) and Sediment Yield(SY) in the Wadi El Hachem watershed, mapping different RUSLE factors as well as A and SY, and studying the influence of rainfall erosivity(R) on A and SY in dry and rainy years. The A results vary from 0 to 410t·ha~(-1)·yr~(-1) with an annual average of 52 t·ha~(-1)·yr~(-1). The Renfro's SDR model was selected as the best model for estimating SY, with standard error, standard deviation, coefficient of variation, and Nash–Sutcliffe efficiency(NSE) values of 0.38%, 0.02, 0.07%, and 1.00, respectively. The average SY throughout the whole watershed is around 27 t·ha~(-1)·yr~(-1). The SY map for the entire Wadi El Hachem watershed revealed that sediment production zones are mainly concentrated in the Northeast of the basin, at the basin's outlet, and in the tributaries of the dam. The simulation results of soil loss and sediment yield in dry and rainy years revealed that R is one of the main factors affecting soil erosion and sediment deposition in the Wadi El Hachem watershed. The mean difference in R factor between dry year and rainy year is 671 MJ·mm·ha~(-1)·h~(-1)·yr~(-1). As a result of this fluctuation, the soil loss and sediment yield have increased by 15 and 8 t·ha~(-1)·yr~(-1), respectively. The results of this research can be used to provide scientific and technical support for conservation and management strategies of the Wadi El Hachem watershed.
  • Spatial distribution and driving factors of sediment net nitrogen mineralization in riparian zone of the Three Gorges Reservoir
    JIA Kai-tao, HE Li-ping, WANG Ke-hong, YU Zhi-guo, LIANG Li-jiao, YU Zhuo-lin, LIN Jun-jie
    2023, 20(02): 381-390.
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    Inorganic nitrogen(N) loss through sediment N mineralization is important for eutrophication surrounding riparian zone. Sediment physicochemical properties have been changed at water-level elevation in riparian zone of the Three Gorges Reservoir(TGR) due to differences in hydrological stress and human activity intensity.However, spatial distribution and driving factor of net N mineralization rate(Nmin) and its temperature sensitivity(Q_(10)) based on the changes in sediment physicochemical properties are still unclear at waterlevel elevation in the riparian zone. A total of 132sediment samples in the riparian zone were collected including 11 transections and 12 water-level elevations on basin scale of the TGR during drying period, to conduct a 28-day incubation at 15℃, 22℃, 29℃ and 36℃. Nmin, total N(TN) and substrate quality(SQ)increased with water-level elevation, while Q_(10) showed an opposite trend(P<0.001). Results of the structural equation model showed that water-level elevation had direct positive effects on TN and SQ(P<0.01). In addition, TN was the major factor that had a direct positive effect on Nmin, and SQ was the crucial factor that had a direct negative effect on Q_(10)(P<0.001). In conclusion, increases in TN and SQ were major driving factors of Nmin and its Q_(10) at water-level elevation, respectively, in riparian zone of the TGR during drying period.
  • Spatial distributions of intra-community tree species under topographically variable conditions
    LV Ting, ZHAO Rong, WANG Ning-jie, XIE Lei, FENG Yue-yao, LI Yao, DING Hui, FANG Yan-ming
    2023, 20(02): 391-402.
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    Growing public awareness of the importance of protecting biodiversity requires the development of forest practices that increase the complexity of stand structure. Understanding the ecological processes of different forest vegetation provide insights into community coexistence mechanisms. In this paper, the spatial patterns of three different communities, evergreen broadleaf forest, deciduous broadleaf forest, and mixed needleleaf and broadleaf forest at Mt. Huangshan,China, were quantified with four structural parameters, the mingling index, the uniform angle index, the diameter dominance index and the crowdedness index. All trees with a diameter at breast height of more than 5 cm were measured. Our analyses highlighted that most trees in the three communities were extremely dense and slightly clumped, with a moderate size differentiation and high mixed structure. In mixed needleleaf and broadleaf forest, the distribution pattern of tree species was better than the other two forests. Overall,spatial patterns in mixed needleleaf and broadleaf forest exhibited a strong stability-effect, that is, the stand had a suitable environment for the stable survival of the forest. With the increasing of elevation, the degree of the mingling index and the crowdedness index increased, however, there was no influence on the uniform angle index and the diameter dominance index. Further, at the same elevation, four structural parameters of shady slope were larger than that of sunny slope. Then we found the relationship between stand spatial structure and environment factors had important influence on forest structure. Our work contributes to the knowledge of population structure, and further provide theoretical basis for the sustainable development of forest resources and protecting biodiversity of Huangshan Mountain. In future studies, it is necessary to explore the limiting factors of community spatial distribution by combining species diversity and functional traits.
  • Influence of rangeland protection and seasonal grazing on aboveground vegetation, forage quality and weight gain of small ruminants – a study in Thar Desert, Pakistan
    ISLAM Muhammad, RAZZAQ Abdul, HASSAN Sawsan, ZUBAIR Muhammad, KALROO Muhammad Waseem, KHAN Attaullah, GUL Shamim, AHMAD Sarfraz, RISCHKOWSKY Barbara Ann, LOUHAICHI Mounir
    2023, 20(02): 403-414.
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    The Thar Desert, Sindh, Pakistan is characterized by low productivity. Besides, economy is based on agriculture, livestock and mining,nevertheless, livestock graze freely on public and private land. The aim of this research was to determine biomass production and to evaluate the effects of continuous and seasonal grazing on protected and unprotected plots. A 45 ha protected rangeland area of Hurrabad in the Umerkot Thar desert was selected and divided into three blocks of 15 ha each. Blocks of the same size were also established in unprotected area. The data for vegetation biomass,canopy cover, forage nutrients and weight gain of animals in two seasons(spring and summer) was collected from both protected and unprotected sites.The results showed that biomass significantly increased in summer in both sites. However, the biomass values in protected sites were significantly higher. Similarly, the vegetation cover also seemed to increase in summer in both protected(90.7% ± 0.29%)and unprotected sites(39.2% ± 0.09%). The foliar concentrations of all nutrients varied significantly with season. The average final live-weight gain for does on the protected grazing sites during the 42-day period in spring and the 96 days after the monsoon was almost double that of does grazing on the unprotected site during 2016 and 2017(P < 0.05).The study concludes that the protection of grazing lands during certain periods can lead to better production of vegetation and livestock and improve range conditions.
  • Characteristics of debris flow impact on a double-row slit dam
    WANG Zhuang, LIU Dao-chuan, YOU Yong, LYU Xiao-bo, LIU Jin-feng, ZHAO Wan-yu, SUN Hao, WANG Dong-wei, LIU Yang
    2023, 20(02): 415-428.
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    To accurately predict impact loads can ensure the safe operation of debris flow control projects. The instantaneous impact process is usually considered in the calculation of the debris flow impact force; however, the redistribution of an impact load after structural regulation is unclear. In this study we deduced the theoretical calculation of a debris flow impact on a double-row slit dam, and carried out a verification experiment on the debris flow impact.The calculation model considers the influence of the debris flow properties, dam arrangement and pile material. The results show that the impact force of the debris flow is obviously affected by the bulk density.When the bulk density is 21 kg/m~3, the maximum impact force on the pile dam is 1.15 times that when the bulk density is 15 kg/m~3, but the time it takes for the debris flow to pass through the dam body is reduced by 60%. The larger the relative pile spacing,the more sufficient the flow space and the lower the maximum impact force. The maximum impact force of relative pile spacing of 0.8 is 12% less than that of elative pile spacing of 0.5. The horizontal distribution of the impact force in the mud depth range is parabolic. The maximum impact force on the centre pier is 1.3 times that of a side pier, and the maximum impact force on the dam body appears at the top of the mud depth range. From the vertical distribution of the impact force, the maximum impact force at the highest mud mark is approximately 70% of that of the bottom. With the increase in the relative pile spacing,the longitudinal maximum impact force distribution first decreases and then increases.
  • Influence of anthropogenic activities on landslide susceptibility: A case study in Solan district, Himachal Pradesh, India
    Sangeeta, S.K.SINGH
    2023, 20(02): 429-447.
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    Landslides in the Himalayan region are primarily controlled by natural parameters, including rainfall, seismic activity, and anthropogenic parameters, such as the construction of large-scale projects like road development, tunneling and hydroelectric power projects and climate change. The parameters which are more crucial among these are a matter of scientific study and analysis. This research,taking Solan district, Himachal Pradesh, India, as the study area, aims to assess the impact of anthropogenic activities on landslide susceptibility at a regional scale. Landslide distribution was characterized into two groups, namely RainfallInduced Landslide(RIL) and Human-Induced Landslide(HIL) based on triggering factors. Multiple data such as slope angle, aspect, profile curvature,distance to drainage, distance to lineament, lithology,distance to road, normalized difference vegetation index(NDVI) and land use land cover(LULC) have been considered for delineating the landslide susceptibility zonation(LSZ) map. The effect of anthropogenic activities on landslide occurrences has been examined through the distribution of landslides along national highways and land use land cover changes(LULCC). Two sets of LSZ maps with a LULC of time interval covering five years(2017 & 2021)were prepared to compare the temporal progression of LULC and landslide susceptibility during the five years. The results indicated the significant impact of anthropogenic activities on the landslide susceptibility. LSZ map of the year 2021 shows that 23% area falls into high and very high susceptible classes and 48% area falls into very low and low susceptibility classes. Compared to LSZ map of 2017,high and very high susceptible classes have been increased by 15%, whereas very low and low susceptible classes have been reduced by 7%. The present case study will help to understand the potential driving parameters responsible for HIL and also suggest the inclusion of LULC in landslide susceptibility analysis. The study will demonstrate new opportunities for research that could help decision-makers prepare for future disasters, both in the Indian Himalayan region and other areas.
  • Rock characteristics and dynamic fragmentation process of the 2018 Daanshan rockslide in Beijing, China
    FAN Tian-zhen, AN Hui-cong, OUYANG Chao-jun, WANG Dong-po
    2023, 20(02): 448-465.
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    This study investigated the failure mechanism associated with the rock mass structure and the dynamic fragmentation process of blocky rocks of the 2018 Daanshan rockslide that occurred on 11 August, 2018. It was found that the initially collapsed rock of this rockslide was partitioned along the unconformity and strata interfaces. We analyzed how the unique rock mass structure, coupled with the road cut and the antecedent rainfall, jointly resulted in its failure. Based on the rock types and geological structures, the initial stratified configuration of a discrete element model was setup to reveal the influences of the local structure. The numerical model was divided into three parts. Part 1 is the basalt of the Nandaling Formation, the normal and shear stiffnesses of the basalt particles are set as 80 MPa and 40 MPa. Parts 2 and 3 are the sandstones interbedded with mudstone and sandstone of the Shihezi Formation, and the normal and shear stiffnesses of these parts were set as 6 MPa and 10MPa, respectively. The dynamic process of the rockslide, particularly the rock fragmentation process,was numerically analyzed using a 3D discrete element method. The numerical results were compared with real-time videos and field investigations. The results show that the rock fragmentation and the final deposition range match well with the real disaster phenomenon, and the calculation accuracy of the rockslide reaches 82.41%. Moreover, a parameter sensitivity analysis was conducted, and classical uniform models under different bonding forces were established; the stratified model can better restore the true state of the fragmentation, movement, and deposition processes of rockslides. Therefore, for complicated rocks with significant differences in lithology, clarifying the rock mass stratigraphy is essential for an accurate reconstruction of the dynamic process of rockslides.
  • Rigid block characteristics on subaerial landslide-tsunamis using a 3D coupled Eulerian-Lagrangian model
    BAO Yi-ding, CHEN Jian-ping, SU Li-jun, ZHOU Xin, YIN Cheng-shan
    2023, 20(02): 466-483.
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    To quantitatively reveal how rock blocks falling into water affect the impulse waves, the influence of a rigid block on induced first wave and second wave is systematically investigated. The block characteristics include the initial velocity, density,volume, and incident angle, and the investigated wave behavior characteristics include the maximum kinetic energy of the water, the transformation ratio of the kinetic energy from the block to the waves, the duration of the waves, the maximum movement speed,and the maximum height and width of the waves. The coupled Eulerian-Lagrangian method(CEL) is introduced to establish the numerical models of the fluid-solid coupling, and a laboratory test of a rigid wedge sliding into water demonstrates that it can reasonably describe the dynamic behavior of a landslide-induced wave. A typical process of a block entering water and its energy variation are described and analyzed in detail. Further, the relationship between each characteristic parameter of the block and the waves is quantitatively investigated and fitted.The simulation results show that energy exchange between the block and the water is very rapid after the block collides with the water. The maximum kinetic energy, maximum velocity, duration, and side dimension of the waves mainly increase non-linearly with the above characteristic parameters of the block.The transformation ratio of the kinetic energy from the block to the water, the first wave, and the second wave are usually below 60%, 45%, and 30%,respectively. The velocity of the block first decreases and then maintains a constant speed after entering the water. The displacement of the block increases linearly with the initial velocity and density of the block and exponentially increases with the block volume at different times. With the increase in the incident angle of the block, the kinetic energy and scale of the second wave increase correspondingly.
  • Evaluation of deep learning algorithms for landslide susceptibility mapping in an alpine-gorge area: a case study in Jiuzhaigou County
    WANG Di, YANG Rong-hao, WANG Xiao, LI Shao-da, TAN Jun-xiang, ZHANG Shi-qi, WEI Shuo-you, WU Zhang-ye, CHEN Chao, YANG Xiao-xia
    2023, 20(02): 484-500.
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    With its high mountains, deep valleys, and complex geological formations, the Jiuzhaigou County has the typical characteristics of a disaster-prone mountainous region in southwestern China. On August 8, 2017, a strong Ms 7.0 earthquake occurred in this region, causing some of the mountains in the area to become loose and cracked. Therefore, a survey and evaluation of landslides in this area can help to reveal hazards and take effective measures for subsequent disaster management. However, different evaluation models can yield different spatial distributions of landslide susceptibility, and thus,selecting the appropriate model and performing the optimal combination of parameters is the most effective way to improve susceptibility evaluation. In order to construct an evaluation indicator system suitable for Jiuzhaigou County, we extracted 12 factors affecting the occurrence of landslides,including slope, elevation and slope surface, and made samples. At the core of the transformer model is a self-attentive mechanism that enables any two of the features to be interlinked, after which feature extraction is performed via a forward propagation network(FFN). We exploited its coding structure to transform it into a deep learning model that is more suitable for landslide susceptibility evaluation. The results show that the transformer model has the highest accuracy(86.89%), followed by the random forest and support vector machine models(84.47% and 82.52%, respectively), and the logistic regression model achieves the lowest accuracy(79.61%).Accordingly, this deep learning model provides a new tool to achieve more accurate zonation of landslide susceptibility in Jiuzhaigou County.
  • What is attractive rural landscape? Differences in the social and expert assessment of the changes in the rural landscape of the Carpathian region in Poland with regard to the need of its protection
    Agata GAJDEK, Barbara KRUPA, Anna NOWAK
    2023, 20(02): 501-515.
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    Contemporary villages of the mountain region are subject to uncontrolled structural and spatial transformations, which cause deformation of centuries-old spatial systems of high cultural and natural value. The aim of the study is to confront the opinions of the inhabitants and experts regarding the condition of the cultural landscape of the villages in south-eastern Poland. This area belongs to the Carpathian region of Central Europe. The historical and economic conditions of the studied region,related to the functioning in the post-war period, and then its breakdown and the development of the free market economy,constitute an interesting background for the proposed research. Local communities still remembering the period of difficulties related to the period of systemic transformations, are currently experiencing a relative prosperity, many difficulties related to the period of systemic transformations, are currently experiencing a relative prosperity, which is also expressed in a completely new, previously unknown way of managing the landscape. Investments implemented in villages are associated by the inhabitants with the improvement of the standards and quality of life.They assess them rather positively. An expert assessment of these landscape transformations indicates their negative dimension and the risk of losing timeless values. The discrepancy in the assessment of experts and local residents creates difficulties in the protection of the rural landscape.Therefore, high-quality visual landscape features among rural residents is necessary from the point of view of its multi-faceted and effective protection.Local initiatives and actions in the field of industry policy should play a significant role in this respect by consolidating the images of a harmonious landscape in the public awareness.
  • An engineering classification system for the detached granite blocks distributed on slopes
    ZHAO Xiu-cheng, ZHAO Xiao-yan, SHEN Wei-gang, LUO Gang
    2023, 20(02): 516-531.
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    Gentle slopes with large amounts of granite blocks are widespread in granitic areas with warm and humid climate. These blocks pose a potential risk to the existing and planned infrastructure. The instability type and geometry of these blocks will influence their motility and destructive power to some extent. This study aims at creating a classification system that can indicate both the shape and the instability type of these blocks and then developing a block removal scheme. The classification system was constructed based on the mechanical stability analysis of blocks on an inclined surface. This analysis identified key factors affecting stability,including block shape, block weathering roundness, the existing state of a block on a slope, and the friction between the block and the slope. The achieved work allowed the establishment of a direct correlation between block geometry and their instability types. The availability of this classification system was validated by field data and experimental data in the literature. The proposal to remove blocks identified as the toppling types, such as cylindrical-toppling types, cuboid-toppling types, cube-toppling types, was put forward to avoid the uneconomical problem of a complete clearance.Meanwhile, this classification provides a foundation for further research on the instability probability of each type of block and the development of a more refined blocks' removal scheme. The classification approach adopted in this paper can provide a reference for the classification of other lithological blocks under similar engineering geological conditions.
  • Dynamic behaviors of rockslides subjected to brittle failure of locked segments
    HU Kai, ZHAO Xiao-yan, ZHANG Guang-ze
    2023, 20(02): 532-541.
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    Locked segments are recognized as a critical role that controls the stability of rock slopes but remain an unclear and challenging problem with respect to their role incorporated into the failure mechanism. In order to study the effect of the locked segments on the initial failure process of rockslides,thirty-six groups of locked segment specimens with three different lithologies were prepared, direct shear tests were carried out to obtain the accelerations caused by brittle failure of the locked segment specimens. Experiment results showed that the maximum accelerations caused by the brittle failure of locked segment specimens was 2.91 g in the horizontal direction, and 3.18 g in the vertical direction. We took the Wangjiayan rockslide in 2008 Wenchuan earthquake as an example, the critical balance condition of the sliding mass under combined effect of gravity and accelerations induced by brittle failure of locked segment was analyzed, which indicated that the initial failure process of the Wangjiayan rockslides was notably influenced by the existence of the locked segment. The departure acceleration and direction of the Wangjiayan rockslide were proposed. The study results can provide a new insight into the understanding of the initial failure mechanism of rockslides with locked segments.
  • Stabilized effects of L-S cement-mixed batter pile composite foundation for existed warm frozen soil subgrade
    SUN Gao-chen, YAO Gang, ZHANG Jian-ming, LI Bo, LI Jun-qi, LIAN Wei-ping, WEI Yi
    2023, 20(02): 542-556.
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    In permafrost regions with warm frozen soil, subgrade thaw-collapse phenomenon commonly occurs, facing thaw collapse problems of the existed frozen soil subgrade, thus it is difficult to use traditional methods such as active cooling and passive protection technology to stabilize the existed warm frozen soil subgrade. This study derives a novel stabilizer method, a long-short(L-S) cement-mixed batter pile composite foundation to stabilize the existed warm frozen soil subgrade. To solve the thawcollapse problems in warm frozen soil subgrade, high water content and large compressibility characteristics were compared between soft soil and warm frozen soils. Theoretical analysis of heat conduction and numerical simulation of finite element model were used to study the freeze–thaw process and evaluate the stabilized effects of the L-S cement-mixed batter piles on the warm frozen soil foundation of the Qinghai-Tibet Highway.Furthermore, the thaw process and mechanical properties of foundation and piles were analyzed by introducing the hydration heat factor in the thermodynamic control equation. The results indicate that the thawing displacement of the existed warm frozen soil subgrade was reduced owing to the “support” and “grasp” effects of the L-S cement-mixed batter piles on the surrounding soil. The composite ground formed by strengthening the warm frozen ground with batter piles could considerably improve the bearing capacity of the existed warm frozen ground, effectively restrain the deformation of the upper embankment, and improve the strength of the ground. The analysis can provide method for the construction design of cement mixing batter pile foundation in cold regions.
  • Thermal-water-salt coupling process of unsaturated saline soil under unidirectional freezing
    LUO Chong-liang, YU Yun-yan, ZHANG Jing, TAO Jing-yan, OU Qing-jie, CUI Wen-hao
    2023, 20(02): 557-569.
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    Salinization and desertification are closely related to water-salt migration caused by a temperature gradient. Based on the Darcy Law of unsaturated soils, the law of energy conservation and the law of mass conservation, the thermal-water-salt coupling mathematical model of unsaturated frozen saline soil was established. The model considered the latent heat of phase change, crystallization impedance, crystallization consumption and complete precipitation of solute crystallization in ice. In order to verify the rationality of the model, the unidirectional freezing test of unsaturated saline soil was carried out in an open system with no-pressure water supplement to obtain the spatial distribution of temperature, moisture and salt in the saline soil.Finally, numerical simulations are implemented with the assistance of COMSOL Multiphysics. Validation of the model is illustrated by comparisons between the simulation and experimental data. The results demonstrated that the temperature within saline soil changes with time and can be divided into three stages, namely quick freezing stage, transitional stage and stable stage. The water and salt contents in the freezing zone are layered, with peak values at the freezing front. The coupled model could reveal the heat-mass migration mechanism of unsaturated frozen saline soil and dynamically describe the freezing depth and the movement law of the freezing front, ice and salt crystal formation mechanism, and the change law of thermal conductivity and permeability coefficient.
  • Application of a new basalt fiber-reinforced polymer anchorage structure in the tunnel–slope system under rainfall action
    TANG Lin, WU Hong-gang, WEI Hong, FENG Kang, RENG Guo-jun
    2023, 20(02): 570-584.
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    The application of basalt fiber-reinforced polymer(BFRP) anchors has gained significant attention, particularly in the field of geotechnical anchorage engineering because of its high strength and corrosion resistance. The research on the applicability of BFRP anchor in a tunnel–slope system under rainfall is of practical significance to solve the problem of instability damage to anchored slopes caused by corrosion of steel anchors. In this study,model tests of BFRP and steel anchorage structures were conducted to compare their reinforcement capability in a tunnel–slope system under heavy rainfall. The results show that the BFRP anchorage structure is better than the steel in coordinating slope deformation and stabilizing earth pressure around the tunnel. The deformation of slopes under rainfall is classified into four stages: initial, isokinetic,accelerated, and blocked deformations. BFRP anchors have the same axial strain distribution pattern as the steel anchors, and they are convexly distributed along the axial direction of the anchors. The correlation analysis and Pearson linear correlation analysis of the multi-attribute data of the slope and BFRP anchors showed a positive correlation among BFRP anchor strain, earth pressure inside the slope, slope deformation displacement, and accumulated rainfall.These research results provide a basis and reference for the application of BFRP anchors in the anchorage engineering of the tunnel–slope system under rainfall action.