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过刊目录

  • 2022年, 19卷, 第03期
    刊出日期：2024-06-19
      
  • 全选
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  • Two-tiered reconstruction of Late Pleistocene to Holocene changes in the freezing level height in the largest glacierized areas of the Colombian Andes
    Daniel RUIZ-CARRASCAL, Daniel GONZáLEZ-DUQUE, Isabel RESTREPO-CORREA
    2022, 19(03): 615-636.
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    One way of deducing vertical shifts in the altitudinal distribution of Colombian high-altitude páramo environments is by inferring fluctuations in the height of the local freezing level. In our research, we are implementing two complementary approaches to reconstruct Late Pleistocene to Holocene changes in the freezing level height(FLH) in two of the most extensively glacier-covered areas of the northern Andes. We combined remote sensing and field-based geomorphological mapping with time-series reconstruction of changes in the altitude of the 0°C isotherm. Changes in the FLH were based on alreadypublished ～30 kyr paleo-reconstructions of sea surface temperatures(SSTs) of the eastern tropical Pacific and the western tropical Atlantic, as well as on reconstructed long-term sea level changes and empirical orthogonal functions of present-day(historical) Indo-Pacific and tropical Atlantic SST anomalies. We also analyzed the probability distribution of air-sea temperature differences and the spatial distribution of grid points with SSTs above the minimum threshold necessary to initiate deep convection. We considered available historical nearsurface and free air temperature data of ERA-Interim reanalysis products, General Circulation Model(GCM) simulations, weather stations, and(deployed by our group) digital sensors, to assess the normal Environmental Lapse Rates(ELRs) at the regional to local scale. The combined maps of glacial landforms and our reconstructed FLHs provided us with a wellfounded inference of potential past glacier advances, narrowing down the coarse resolution of ice margins suggested by previous research efforts. The extent of the areas with temperatures below the freezing point suggested here for the summits of our main study site exceeds in magnitude the corresponding glacier icecaps and front advances proposed by previous studies. Conversely, our average lowest altitudes of the FLH for our comparative site are consistently above the main glacier-front advances previously suggested. Our results indicate that, compared to the maximum upward changes that likely took place over the past ca. 20,000 years in our two areas of interest, the observed(present-day) upward shifts of the FLH have occurred at a rate that significantly surpasses our inferred rates. Our study helps fill the gaps in understanding past climatic changes and present trends in the region of interest and provides some insights into analyzing the signals of natural and anthropogenic climate change.
  • Distribution of algae and cyanobacteria of biological soil crusts along the elevation gradient in mountain plant communities at the Northern Urals(Russian European Northeast)
    IV NOVAKOVSKAYA, EN PATOVA, YA DUBROVSKIY, AB NOVAKOVSKIY, EE KULYUGINA
    2022, 19(03): 637-646.
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    This paper describes the biodiversity of cyanobacteria and microalgae of biological soil crusts(BSC) on bare substrates in different mountain vegetation types at the Northern Urals. In total, we identified 99 algal species from six divisions in all sampled sites. The species diversity and structure of BSC algal communities show a relationship with environmental factors(altitude, soil p H and humidity, and illumination). Taxonomic diversity of algae decreases along the altitude gradient from mountain meadow to mountain tundra. Algae and cyanobacteria species from six divisions were identified in meadow communities, five in mountain forests and four in mountain tundra. We observed a positive correlation between species diversity of phototrophic microorganisms and altitude in the forest communities, but a negative correlation in the tundra. The dominant complex of cyanobacterial and algal species in BSC was specific for each type of plant community and was reflective of the habitat conditions. The species diversity and morphological organization of the BSC algae thalli can be used as a criterion for the ongoing assessment of climatic changes in high latitudes and mountain regions.
  • Humus horizon development during natural forest succession process in the Polish Carpathians
    Justyna SOKO?OWSKA, Agnieszka JóZEFOWSKA, Tomasz ZALESKI
    2022, 19(03): 647-661.
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    As a result of socio-economic changes and land abandonment, the main ecological driver of the Carpathian landscape is the progression of the natural forest succession process. Thus, aspects of this process have become worthy of attention, especially in the context of carbon sequestration and the management of protected areas. Soil processes, especially within the topsoil, are some of the most susceptible to change, due to the accumulation of organic matter during such land-use transformations. The purposes of this study were to investigate the differences in topsoil development using the A Horizon Development Index(ADI) and to study the composition of humic substances and advanced organic matter humification in different land-use areas in selected Carpathian national parks, i.e. Bieszczady, Magura and Pieniny National Parks in southern Poland. Additionally, a goal of this study was to compare the ADI and the spectroscopic coefficients of humic substances as indicators of the degree of humus horizon shaping as well as advanced organic matter humification. In total, ten transects were selected, each consisting of three different land-use areas: semi-natural meadow, successional forest and old-growth forest. Soil colour was determined in fresh and air-dried samples using the Munsell colour chart. In air-dried soil samples p H, soil texture, total organic carbon and total nitrogen were measured. Humic substances were extracted and further characterized by UV-VIS spectroscopy. The ADI confirmed the influence of natural forest succession on soil colour darkening and the development of the uppermost soil layer. Spectroscopic analyses of humic substances showed two different patterns depending on soil depth. In the 0–10 cm layer, natural forest succession reduced the rate of the humification process and decreased the degree of maturity of fulvic acids; in the 10–20 cm layer, it led to an increase in the rate of the humification process and a decrease in the content of humic and fulvic acids at the beginning of the transformation. The comparison of two different indicators of soil development – the ADI and the spectroscopic coefficients of humic substances(Q_(4/6), Q_(2/4), Q_(2/3), Δ log K) – indicated that these indexes are based on different features of soil and cannot be used interchangeably.
  • Relationship between the productivity of Pinus brutia Ten. and site characters, the Taurus Mountains, Turkey
    Emre KUZUGüDENL?
    2022, 19(03): 662-672.
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    Turkish red pine is an important forest tree species because of its role in the ecosystem whose range includes many countries in the eastern Mediterranean basin. In addition, red pine is a preferred forest tree species due to rapid growth, usage in afforestation in arid areas and the production of non-wood forest products such as resin. The aim of the study was to examine the relationship between the productivity of red pine and ecosystem in the lower and middle belt of the Taurus Mountains, and to determine the interrelations between the productivity of red pine and ecosystem. Multivariate analyses(multiple regression analysis and artificial neural networks) were used to model the efficiency(biomass production) of red pine. From the multivariate analyses, a productivity model of the species was created with the slope, soil depth, and precipitation in the driest variables. A significant correlation was found between site index and site factors in the driest quarter. These variables had a statistically significant relationship with the site index in the multiple regression analysis. The forecast power of the model was 0.33. Of the methods used, the artificial neural network consisting of 2 L10 N(2 Layers 10 Neurons) had the highest margin of explanation(R~2= 0.71) and the lowest margin of error. This model has the potential to open land aimed for afforestation studies with red pine in forestry areas. The results will shed light on afforestation studies to be carried out in the Western Mediterranean region and in similar ecosystems.
  • Simulation of critical transitions and vulnerability assessment of Tibetan Plateau key ecosystems
    YANG Fei, MA Chao, FANG Hua-jun
    2022, 19(03): 673-688.
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    Critical transitions in ecosystems may imply risks of unexpected collapse under climate changes, especially vegetation often responds sensitively to climate change. The type of vegetation ecosystem states could present alternative stable states, and its type could signal the critical transitions at tipping points because of changed climate or other drivers. This study analyzed the distribution of four key vegetation ecosystem types: desert, grassland, forest-steppe ecotone and forest, in Tibetan Plateau in China, using the latent class analysis method based on remote sensing data and climate data. This study analyzed the impacts of three key climate factors, precipitation, temperature, and sunshine duration, on the vegetation states, and calculated the critical transition tipping point of potential changes in vegetation type in Tibetan Plateau with the logistic regression model. The studied results showed that climatic factors greatly affect the vegetation states and vulnerability of the Tibetan Plateau. In comparison with temperature and sunshine duration,precipitation shows more obvious impact on differentiations of the vegetations status probability. The precipitation tipping point for desert and grassland transition is averagely 48.0 mm/month, 70.7 mm/month for grassland and forest-steppe ecotone, and 115.0 mm/month for forest-steppe ecotone and forest. Both temperature and sunshine duration only show different probability change between vegetation and non-vegetation type, but produce opposite impacts. In Tibetan Plateau, the transition tipping points of vegetation and nonvegetation are about 12.1°C/month and 173.6 h/month for the temperature and sunshine duration, respectively. Further, vulnerability maps calculated with the logistic regression results presented the distribution of vulnerability of Tibetan Plateau key ecosystems. The vulnerability of the typical ecosystems in the Tibetan Plateau is low in the southeast and is high in the northwest. The meteorological factors affect tree cover as well as the transition probability that occurs in different vegetation states. This study can provide reference for local government agencies to formulate regional development strategies and environmental protection laws and regulations.
  • Projected change in precipitation forms in the Chinese Tianshan Mountains based on the Back Propagation Neural Network Model
    REN Rui, LI Xue-mei, LI Zhen, LI Lan-hai, HUANG Yi-yu
    2022, 19(03): 689-703.
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    In the context of global warming, precipitation forms are likely to transform from snowfall to rainfall with a more pronounced trend. The change in precipitation forms will inevitably affect the processes of regional runoff generation and confluence as well as the annual distribution of runoff. Most researchers used precipitation data from the CMIP5 model directly to study future precipitation trends without distinguishing between snowfall and rainfall. CMIP5 models have been proven to have better performance in simulating temperature but poorer performance in simulating precipitation. To overcome the above limitations, this paper used a Back Propagation Neural Network(BNN) to predict the rainfall-to-precipitation ratio(RPR) in months experiencing freezing-thawing transitions(FTTs). We utilized the meteorological(air pressure, air temperature, evaporation, relative humidity, wind speed, sunshine hours, surface temperature), topographic(altitude, slope, aspect) and geographic(longitude, latitude) data from 28 meteorological stations in the Chinese Tianshan Mountains region(CTMR) from 1961 to 2018 to calculate the RPR and constructed an index system of impact factors. Based on the BNN, decision-making trial and evaluation laboratory method(BP-DEMATEL), the key factors driving the transformation of the RPR in the CTMR were identified. We found that temperature was the only key factor affecting the transformation of the RPR in the BP-DEMATEL model. Considering the relationship between temperature and the RPR, the future temperature under different representative concentration pathways(RCPs)(RCP2.6/RCP4.5/RCP8.5) provided by 21 CMIP5 models and the meteorological factors from meteorological stations were input into the BNN model to acquire the future RPR from 2011 to 2100. The results showed that under the three scenarios, the RPR in the number of months experiencing FTTs during 2011-2100 will be higher than that in the historical period(1981-2010) in the CTMR. Furthermore, in terms of spatial variation, the RPR values on the south slope will be larger than those on the north slope under the three emission scenarios. Moreover, the RPR values exhibited different variation characteristics under different emission scenarios. Under the low-emission scenario(RCP2.6), as time passed, the RPR values changed slightly at more stations. Under the mediumemission scenario(RCP4.5), the RPR increased in the whole CTMR and stabilized on the north slope by the end of this century. Under the high-emission scenario(RCP8.5), the RPR values increased significantly through the 21 st century in the whole CTMR. This study may help to provide a scientific management basis for agricultural production and hydrology.
  • Rill flow velocity affected by the subsurface water flow depth of purple soil in Southwest China
    TAO Ting-ting, CHEN Shi-qi, CHEN Xiao-yan
    2022, 19(03): 704-714.
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    Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes. However, it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity. Laboratory experiments were performed to measure the rill flow velocity on purple soil slopes containing a subsurface water flow layer with the electrolyte tracer method considering 3 subsurface water flow depths(SWFDs: 5, 10, and 15 cm), 3 flow rates(FRs: 2, 4, and 8 L min~(-1)), and 4 slope gradients(SGs: 5°, 10°, 15°, and 20°). As a result, the pulse boundary model fit the electrolyte transport processes very well under the different SWFDs. The measured rill flow velocities were 0.202 to 0.610 m s~(-1) under the various SWFDs. Stepwise regression results indicated a positive dependence of the flow velocity on the FR and SG but a negative dependence on the SWFD. The SWFD had notable effects on the rill flow velocity. Decreasing the SWFD from 15 to 5 cm increased the flow velocity. Moreover, the flow velocities under the 10-and 15-cm SWFDs were 89% and 86%, respectively, of that under the 5-cm SWFD. The flow velocity under the 5-, 10-and 15-cm SWFDs was decreased to 89%, 80%, and 77%, respectively, of that on saturated soil slopes. The results will enhance the understanding of rill flow hydrological processes under SWFD impact.
  • Estimation of permafrost thermal behavior using Fourier series model
    ZHANG Yan-yu, ZANG Shu-ying, ZHAO Lin, MA Da-long, LIN Yue, LI Hao
    2022, 19(03): 715-725.
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    Permafrost, being an important component of the cryosphere, is sensitive to climate change. Therefore, it is necessary to investigate the change of temperature within permafrost. In this study, we proposed a Fourier series model derived from the conduction equation to simulate permafrost thermal behavior over a year. The boundary condition was represented by the Fourier series and the geothermal gradient. The initial condition was represented as a linear function relative to the geothermal gradient. A comparative study of the different models(sinusoidal model, Fourier series model, and the proposed model) was conducted. Data collected from the northern Da Xing'anling Mountains, Northeast China, were applied for parameterization and validation for these models. These models were compared with daily mean ground temperature from the shallow permafrost layer and annual mean ground temperature from the bottom permafrost layer, respectively. Model performance was assessed using three coefficients of accuracy, i.e., the mean bias error, the root mean square error, and the coefficient of determination. The comparison results showed that the proposed model was accurate enough to simulate temperature variation in both the shallow and bottom permafrost layer as compared with the other two Fourier series models(sinusoidal model and Fourier model). The proposed model expanded on a previous Fourier series model for which the initial and bottom boundary conditions were restricted to being constant.
  • Seismic hazard prediction using multispectral amplification maps in a complex topographic area: A case study of Qiaozhuang town, Sichuan Province, Southwest China
    LUO Yong-hong, XU Qiang, ZHAN Wei-wei, GRELLE Gerardo
    2022, 19(03): 726-739.
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    Earthquakes can cause widely distributed slope failures and damage in mountainous areas. The accurate prediction of ground motions in mountainous areas is essential for managing the seismic risk of urban cities near mountains but is restricted primarily by complex seismic site amplification effects in areas of uneven terrain. This study selected Qiaozhuang town located in the Qingchuan–Pingwu fault zone, Southwest China, as a case study. A simulator for mapped seismic responses using a hybrid model(Si Se RHMap) was applied to compute the multispectral seismic topographic amplification maps at the three slope units surrounding Qiaozhuang town(Weigan hill, Mt. Dong, and Mt. Shizi). Post-earthquake damage survey maps, 1 D seismic site response spectral ratios, and H/V spectral ratios of earthquake data were used to validate the computed seismic site amplification factors and resonance frequencies. The results suggest that strong topographic amplification effects usually occur at distinct slope locations, such as hilltops, convex slope positions, upslope, and narrow ridges. The computed topographic amplification factors in the study area reached up to 2.4 at upslope or hilltops, and the resonance frequencies were between 3 and 10 Hz. Topographic effects can be as important as stratigraphic effects when assessing seismic amplification effects in the study area. We conclude that both topographic and stratigraphic effects should be considered in the comprehensive seismic hazard assessment of the study area or other similar mountain towns.
  • Field investigation and numerical simulation on rockfalls in Zhangmu Town, Tibet, China
    WANG Zhong-fu, LIU Han-dong, HE Si-ming, BI Dan
    2022, 19(03): 740-755.
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    Zhangmu Town in Tibet of China, which lies in the southern piedmont of the median Himalayas, is a small but strategically important port of trade exchange between China and Nepal. Many rockfall events have occurred in Zhangmu since 1970, resulting in huge economic losses and serious influence on the bilateral trade. We conducted a detailed field investigation on the high and steep slope in Zhangmu Town, and analyzed the distribution features, stability, failure modes and evolution of dangerous rocks of potential rockfalls. Then we numerically simulated the movement path, velocity and accumulation forms of the rockfall with PFC~(3D) program. The results indicated that the dangerous rock belt could be divided into three sections, namely, unstable section, slightly stable section and basically stable section. It was estimated that the rock debris and single dangerous rock would be unstable in the case of earthquakes or rainstorms. Due to the terrain constraints, the fallen rocks would scatter near the mouth of the Zhangmu ditch and in the Buqu River through multiple times of rolling, collision-induced diversion and bouncing. Without reinforcement, the rockfall could cause serious damage to the car parks, gas stations and National Highway 318 along the line from Zhangmu Town to Zhangmu ditch. Based on the field survey and numerical simulation, we recommended rockfall removal and interception as the major prevention measures, and protective sheds as auxiliary measure.
  • Stability and deformation of Xiaozhuang landslide: A large-scale creeping landslide in Gansu, China
    ZHANG Ze-lin, WANG Tao
    2022, 19(03): 756-770.
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    Information about the long-term spatiotemporal evolution of landslides can improve our understanding of the landslide development process and can help prevent landslide disasters. This paper describes the Xiaozhuang landslide triggered by a historical earthquake and rainfall in Tianshui, Northwest China. The landslide is dominated by rotational-sliding movement. Several new failures and many fissures formed in the landslide area as a result of the 2013 Ms 6.6 Minxian earthquake and rainfall. Accordingly, field investigations, borehole drilling, geotechnical laboratory tests, and numerical calculations were conducted to study the mechanism of the landslide and to forecast its stability. A triaxial creep test of the slip soil indicates that the axial deformation of the mudstone increases with increasing water content. Numerical simulations suggest that failure is prone to occur within the deep part of the landslide under earthquake conditions. If the input seismic acceleration exceeds 0.2 g, the landslide will become unstable. Furthermore, the horizontal peak ground acceleration near the surface of the landslide is greater than that at depth. During a strong earthquake, the unstable regions are primarily located in the middle of the landslide and at its crest. When the rainfall intensity rate is 200 mm/d, the factor of safety is 1.319 and a dangerous zone appears in the lower and middle parts of the landslide.
  • Emergency road network structure and planning optimization in mountainous regions in Southwest China under earthquake scenarios
    WEI Meng, HUANG Yong, WAN Dan, DENG Liang-kai
    2022, 19(03): 771-780.
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    Emergency road networks(ERNs), an important part of local disaster prevention systems, can provide security to residents and their property. Exploring the ERNs structure is of great significance in terms of promoting disaster prevention and establishing road safety in dangerous mountainous areas. This study considered the ERNs of the Kangding section of the Dadu River Basin as the area for a case study. Complex Network Analysis was used to examine the relationship between the four characteristic indicators of mountain roads and the degree of earthquake impacts under the Lushan, Wenchuan, and Kangding Earthquake scenarios. Based on the analysis results, the southwest mountain road network was evaluated; then, computer simulations were used to evaluate the structural changes in the road network after index changes. The network was optimized, and the corresponding emergency avoidance network was proposed to provide a reference for the establishment of the mountainous ERN. The results show that the overall completeness of the mountainous ERNs in Southwest China is poor and prone to traffic accidents. Moreover, the local stability is poor, and the network is susceptible to natural hazards. The overall structure of the road network is balanced, but that of certain road sections is not. Road sections with different attributes present a “gathering-scattering” spatial distribution, i.e, some sections are clustered together while others are far apart. Accordingly, a planning optimization strategy is proposed to better understand the complexity and systematic nature of the mountainous ERN as a whole and to provide a reference for disaster prevention and mitigation planning in mountainous regions in Southwest China.
  • Cumulative damage effect on debris slopes under frequent microseisms
    YANG Zhong-ping, LI Shi-qi, TIAN Xin, HU Yuan-xin, LI Wan-kun
    2022, 19(03): 781-797.
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    Debris slopes are widely distributed across the Three Gorges Reservoir area in China, and seasonal fluctuations of the water level in the area tend to cause high-frequency microseisms that subsequently induce landslides on such debris slopes. In this study, a cumulative damage model of debris slope with varying slope characteristics under the effects of frequent microseisms was established, based on the accurate definition of slope damage variables. The cumulative damage behaviour and the mechanisms of slope instability and sliding under frequent microseisms were thus systematically investigated through a series of shaking table tests and discrete element numerical simulations, and the influences of related parameters such as bedrock, dry density and stone content were discussed. The results showed that the instability mode of a debris slope can be divided into a vibration-compaction stage, a crack generation stage, a crack development stage, and an instability stage. Under the action of frequent microseisms, debris slope undergoes the last three stages cyclically, which causes the accumulation to slide out in layers under the synergistic action of tension and shear, causing the slope to become destabilised. There are two sliding surfaces as well as the parallel tensile surfaces in the final instability of the debris slope. In the process of instability, the development trend of the damage accumulation curve remains similar for debris slopes with different parameters. However, the initial vibration compaction effect in the bedrock-free model is stronger than that in the bedrock model, with the overall cumulative damage degree in the former being lower than that of the latter. The damage degree of the debris slope with high dry density also develops more slowly than that of the debris slope with low dry density. The damage development rate of the debris slope does not always decrease with the increase of stone content. The damage degree growth rate of the debris slope with the optimal stone content is the lowest, and the increase or decrease of the stone content makes the debris slope instability happen earlier. The numerical simulation study also further reveals that the damage in the debris slope mainly develops in the form of crack formation and penetration, in which, shear failure occurs more frequently in the debris slope.
  • Rock temperature variability in high-altitude rockfall-prone areas
    Guido NIGRELLI, Marta CHIARLE, Andrea MERLONE, Graziano COPPA, Chiara MUSACCHIO
    2022, 19(03): 798-811.
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    In a context of cryosphere degradation caused by climate warming, rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes. In order to improve the knowledge of this critical relationship, it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions, and also to increase local scale studies, increasing the quality and the comparability of the data. This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions, by means of the measurement uncertainty. Under such approach, data and results from temperature measurements carried out in the Bessanese high-elevation experimental site(Western European Alps) are illustrated. The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations, depths and lithotypes, within 0.10 °C of overall uncertainty. This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements; that there are strong differences between air temperature and near-surface rock temperature; and that there are significant differences of rock temperature acquired in different aspect conditions. Finally, solar radiation, slope/aspect conditions and lithotype, seem to be the main driving factors of rock temperature.
  • Load transfer laws of tensile anchors in rock masses with weak interlayers based on a shear-slipping updating model
    WANG Yan, XIANG Xin, LI Chang-dong, ZHU Guo-qiang, SONG Cheng-bin, XIAN Jin-ye, ZHANG Jia-jun
    2022, 19(03): 812-825.
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    The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated, considering the nonuniform stress of the horizontally layered rock mass along anchors. An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface. Based on the improved model, analytical solutions of the axial force, shear stress distribution and load-displacement relationship considering the residual stress stage were established. The effects of the stratigraphic sequence, pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions. The results were verified by applying the finite difference numerical simulation method. The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient. The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth. Due to the existence of weak interlayers, the shear stress mutates at the weak and hard rock interface, and the axial force appears to “rebound” at the bottom of the anchored section. Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor. The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined. This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses, providing a theoretical basis for anchor design.
  • An elasto-plastic and viscoplastic damage constitutive model for dilatancy and fracturing behavior of soft rock squeezing deformation
    HUANG Xing, LIU Quan-sheng, BO Yin, LIU Bin, DING Zi-wei, ZHANG Quan-tai
    2022, 19(03): 826-848.
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    Soft rock squeezing deformation mainly consists of pre-peak damage-dilatancy and post-peak fracture-bulking at the excavation unloading instant, and creep-dilatancy caused by time-dependent damage and fracturing. Based on the classic elastoplastic and Perzyna over-stress viscoplastic theories, as well as triaxial unloading confining pressure test and triaxial unloading creep test results, an elastoplastic and viscoplastic damage constitutive model is established for the short-and long-term dilatancy and fracturing behavior of soft rock squeezing deformation. Firstly, the criteria for each deformation and failure stage are expressed as a linear function of confining pressure. Secondly, the total damage evolution equation considering time-dependent damage is proposed, including the initial damage produced at the excavation instant, in which the damage variable increases exponentially with the lateral strain, and creep damage. Thirdly, a transient five-stages elasto-plastic constitutive equation for the short-term deformation after excavation that comprised of elasticity, pre-peak damage-dilatancy, post-peak brittle-drop, linear strain-softening, and residual perfectly-plastic regimes is developed based on incremental elasto-plastic theory and the nonassociated flow rule. Fourthly, regarding the timedependent properties of soft rock, based on the Perzyna viscoplastic over-stress theory, a viscoplastic damage model is set up to capture creep damage and dilatancy behavior. Viscoplastic strain is produced when the stress exceeds the initial static yield surface fs; the distance between the static yield surface fs and the dynamic yield surface fd determines the viscoplastic strain rate. Finally, the established constitutive model is numerically implemented and field applied to the-848 m belt conveyer haulage roadway of Huainan Panyidong Coal Mine.Laboratory test results and in-situ monitoring results validate the rationality of the established constitutive model. The presented model takes both the transient and time-dependent damage and fracturing into consideration.
  • Seismic vulnerability assessment of urban buildings using the rough set theory and weighted linear combination
    Yasaman ASADI, Najmeh NEYSANI SAMANY, Majid KIAVARZ MOQADAM, Ata ABDOLLAHI KAKROODI, Meysam ARGANY
    2022, 19(03): 849-861.
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    Seismic vulnerability assessment of urban buildings is among the most crucial procedures to post-disaster response and recovery of infrastructure systems. The present study proceeds to estimate the seismic vulnerability of urban buildings and proposes a new framework training on the two objectives. First, a comprehensive interpretation of the effective parameters of this phenomenon including physical and human factors is done. Second, the Rough Set theory is used to reduce the integration uncertainties, as there are numerous quantitative and qualitative data. Both objectives were conducted on seven distinct earthquake scenarios with different intensities based on distance from the fault line and the epicenter. The proposed method was implemented by measuring seismic vulnerability for the seven specified seismic scenarios. The final results indicated that among the entire studied buildings, 71.5% were highly vulnerable as concerning the highest earthquake scenario(intensity=7 MM and acceleration calculated based on the epicenter), while in the lowest earthquake scenario(intensity=5 MM),the percentage of vulnerable buildings decreased to approximately 57%. Also, the findings proved that the distance from the fault line rather than the earthquake center(epicenter) has a significant effect on the seismic vulnerability of urban buildings. The model was evaluated by comparing the results with the weighted linear combination(WLC) method. The accuracy of the proposed model was substantiated according to evaluation reports. Vulnerability assessment based on the distance from the epicenter and its comparison with the distance from the fault shows significant reliable results.
  • Land development suitability analysis for transport planning evaluation and optimization in mountainous ecological region
    ZHU Gao-ru, WANG Man, LI Qi-li, LIU Jie, ZHAO Yan-ni, GAO Jia-wei, XU Hong-lei
    2022, 19(03): 862-873.
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    Transportation planning is a critical component for creating an orderly, intensive, and sustainable pattern of land development. By comprehensively considering the potential and suitability of transport construction, a comprehensive method combining resources and environmental carrying capacity(RECC) and land development suitability(LDS) was developed by using techniques of GIS, analytic hierarchy process(AHP) and threedimensional magic cube. Taking Aba prefecture in Sichuan Province of Southwest China as a case study, LDS for transportation was analyzed from three aspects, including overall planning layout, different transport modes, and transportation projects. The results showed that the transport planning scales of most counties in Aba were suitable, and the order of LDS of different transport modes was railway > highway = superhighway > tourism track, which already included 42 new transportation projects. We found that two counties(Maoxian County and Jiuzhaigou County) should improve the ecological protection level of transportation, in which the railway network construction should be encouraged, and some transportation projects with low LDS should be postponed or constructed harmlessly. We suggest the combination of RECC and LDS for transportation could enhance the territorial space optimization and sustainable transport construction.
  • A bi-scale assessing framework for aesthetic ecosystem services of villages in a world heritage site
    DING Yin-ping, LIU Zhi-lin, JIAO Yuan-mei, XU Qiu-e, ZHANG Kan-feng, LIU Cheng-jing, CHEN Fan
    2022, 19(03): 874-891.
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    The relative spatial scale relationship of observers and ecosystem and their aesthetic dynamic interaction process are fundamental to evaluation and optimization of aesthetic ecosystem service(AES). A comprehensive and efficient framework for the assessment of AES is lack in the integration of scale relationship and dynamic process. This study took 9 villages in 4 different developmental stages(traditional, folk, rapidly changed, newly built) in Honghe Hani Rice Terraces, a world heritage site, as the research object. From two scales, viewing from inside and outside, the bi-scale assessing framework was established, which includes the three components of interaction process, connection area(as precondition of interaction), quality(as result of interaction), and influencing factors of quality(elements' characteristics of villages). Among them, the connection areas were evaluated with visual and traffic accessibility along the route. The quality and influencing factors were evaluated through participatory preferences methods by expert group. The influencing factors include 9 characteristics, such as, space size, architecture layout, vegetation species richness, color diversity. The results suggested that villages with high AES quality and low accessibility need to be optimized, and the key influencing factors are space size, architecture layout, color harmony and surrounding sanitation. Therefore, the bi-scale assessing framework can provide important references for decision making and visual protection regulations on the villages.
  • Assessment on the component pattern of mountain vacation potential suitability in Hunan Province, China
    DU Ting-ting, LI Da-li, ZHONG Yong-de
    2022, 19(03): 892-908.
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    In China, mountain destinations offer more opportunities for vacation than beaches and springs, with a larger national coverage, richer landscapes and various diverse folk cultures. Hunan Province, for example, serves as a typical mountain tourism destination. Our research aims to assess the potential suitability and component pattern of holidaymaking in Hunan Province to support for scientific endeavors and sustainable use of mountain resources in Hunan. An approach for mapping potential suitability was constructed based on Weighted Linear Combination(WLC) of six primary factors including terrain, climate suitability period, biology and environment, human activity culture, hydrological landscape, and road infrastructure, which is calculated on the base of eleven secondary factors used as suitability criteria. Analytic hierarchy process(AHP) and geographic information system(GIS) were also integrated into the evaluation models to prepare six single and complex factor suitability maps for mountain vacation. Multivariate clustering was used to clarify the component pattern of single factor combinations in each mountain vacation suitability index(MVSI) class. The results have shown that: 1) Regions with high suitability are distributed with characteristics of significant dispersion and limited aggregation; 2) 15.89% of the sample mountains are highly suitable, 30.78% are moderately suitable, 42.61% are marginally suitable and 10.72% are poorly suitable; 3) The complexity of index combination corresponding to each level is different; 4) Different combinations emphasize different destination needs. The study reveals the suitability class, characteristics, and limiting factors of mountain vacation in different geographical locations on the provincial scale. These elements play an instructive role in scientific decision-making and orderly exploitation of resources among Hunan's Mountain destinations. Furthermore, the study can also be used as a basis for the suitability evaluation of mountain vacation in other areas.