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过刊目录

  • 2023年, 20卷, 第07期
    刊出日期：2024-06-19
      
  • 全选
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  • Natural Walls of Anatolia: formation and development of Di? Kayal?klar? as a structural landform(Sivas, Türkiye)
    UZUN Ali, AYLAR Faruk, ZEYBEK Halil ?brahim, GüRG?ZE Serkan, BAHADIR Muhammet, ALEMDA? Sel?uk
    2023, 20(07): 1807-1823.
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    The Di? Kayal?klar? is one of the largest and most striking examples of crests in the world and is located between Eskidere and Bo?az?ren villages of the ?mranl? district of the Sivas province in Türkiye.The crests, which resemble castle walls when viewed from afar, have a real wall pattern due to the rightangled crack system of the bedrock when viewed closely. This study aims at investigating the geomorphological features of the Di? Kayal?klar? and determining how the geological and geomorphological evolution of the Di? Kayal?klar? took place and how the current formation mechanism continues. In the region, the mid-latitude continental climate prevails with cold humid winters and warm dry summers. The bedrock consists of Miocene bedded deposits of different resistance, folded by young tectonic movements. Di? Kayal?klar? was formed by selective erosion of less resistant terrain around a pack of resistant rock on the steeper southern slope of an asymmetrical anticline. It has a length of 4750 m in the approximately northwest-southeast direction, a maximum height of 30 m, and a width varying between 5 and 8 m. In the present morphological appearance of the Di? Kayal?klar?, it can be stated that the structure formed after the tectonic formation process was eroded under the control of the local climate and crest formation was realized. In the following process, the crest experienced a polycyclic process where different landforms were formed.There are smaller landforms such as karren, cave and rock window on Di? Kayal?klar?, and macrofossil beds in some places. This highly attractive geomorphosite,unknown to wider public, should be investigated from various scientific aspects and should be brought to regional tourism by making the necessary infrastructure and promotion studies.
  • Exploring the rules of cropland elevation uplift in China
    YUAN Jin-tao, CHEN Wan-xu, ZENG Jie, YE Xin-yue
    2023, 20(07): 1824-1841.
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    Cropland elevation uplift(CLEU) has recently become a new challenge for agricultural modernization, food security, and sustainable cropland use in China. Uncovering the rules of CLEU is of great theoretical and practical significance for China's sustainable agricultural development and rural revitalization strategy. However, existing studies lack in-depth disclosure of multi-scale CLEU evolution rules, making it difficult to support the formulation of specific cropland protection policies.We analyzed the spatio-temporal evolution and multiscale CLEU in China from 1980 to 2020 using the Lorenz curve, gravity center model, hotspot analysis,and cropland elevation spectrum. The results indicated that the center of gravity of cropland moved to the northeast from 1980 to 2000 and then shifted to the northwest. The spatial distribution of cropland became increasingly imbalanced from 1980 to 2000.The change hotspots clustered in the northwest and the northeast, whereas cold-spots were mainly in southeastern China. The average elevation of cropland increased by 17.38 m, and the elevation uplift rule in different regions differed evidently across scales.From 1980 to 2000, all provinces except Xinjiang,Inner Mongolia, Gansu, and Yunnan exhibited CLEU,with Qinghai, Tibet, Beijing, and Guangdong showing the most noticeable uplifting. The CLEU can alleviate the shortage of cropland to some extent. However,without a planning constraint, the CLEU will lead to the increase of ecological risk and food security risk.
  • Shared-role of vegetation types, elevation and soil affecting plant diversity in an old-tropical mountain hotspot
    Priscilla P.LOIOLA, Leonor Patrícia Cerdeira MORELLATO, Maria Gabriela Gutierrez CAMARGO, Vitor A.KAMIMURA, Jacqueline S.MATTOS, Annia Susin STREHER, Soizig LE STRADIC
    2023, 20(07): 1842-1853.
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    Despite the exceptional species richness and endemism, the environmental drivers of plant diversity along old tropical mountains remain underexplored. The respective importance of vegetation types, elevation, slope, and soil to drive diversity across life-forms is poorly addressed. Here, we tested whether environmental variables drove local and regional plant diversity along an old tropical mountain according to the three main life-forms:graminoids, herbaceous and woody species. We sampled all Angiosperm species on 180 plots across five elevations, at the tropical old-mountain region of Serra do Cipó, South-eastern Brazil. We assessed soil,slope, and vegetation types, and calculated richness and beta-diversity, applying generalized least square models, linear mixed-models and partial Mantel tests to test for relationships. Richness of graminoids and herbaceous species increased with greater elevation and more nutrient-impoverished soils, while woody richness showed the inverse pattern. Beta-diversity was primarily driven by species turnover, correlated with elevation and soil and higher in less dominant vegetation types, with unique species. Despite the limited elevational range in these old mountains, it still played an important role in filtering woody species, while fostering graminoid and herbaceous species. Conservation and restoration actions need to foster the high regional diversity supported by the old mountain heterogeneous landscape and the diversity of life-forms, especially the dominant and highly diverse grassy component.
  • Analyzing geomorphological and topographical controls for the heterogeneous glacier mass balance in the Sikkim Himalayas
    GUHA Supratim, TIWARI Reet Kamal
    2023, 20(07): 1854-1864.
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    Glacier response patterns at the catchment scale are highly heterogeneous and defined by a complex interplay of various dynamics and surface factors.Previous studies have explained heterogeneous responses in qualitative ways but quantitative assessment is lacking yet where an intrazone homogeneous climate assumption can be valid.Hence, in the current study, the reason for heterogeneous mass balance has been explained in quantitative methods using a multiple linear regression model in the Sikkim Himalayan region. At first, the topographical parameters are selected from previously published studies, then the most significant topographical and geomorphological parameters are selected with backward stepwise subset selection methods. Finally, the contributions of selected parameters are calculated by least square methods.The results show that, the magnitude of mass balance lies between-0.003±0.24 to-1.029±0.24 m.w.e.a~(-1) between 2000 and 2020 in the Sikkim Himalaya region. Also, the study shows that, out of the terminus type of the glacier, glacier area, debris cover, ice-mixed debris, slope, aspect, mean elevation, and snout elevation of the glaciers, only the terminus type and mean elevation of the glacier are significantly altering the glacier mass balance in the Sikkim Himalayan region. Mathematically, the mass loss is approximately 0.40 m.w.e.a~(-1) higher in the lake-terminating glaciers compared to the land-terminating glaciers in the same elevation zone. On the other hand, a thousand meters mean elevation drop is associated with 0.179 m.w.e.a-1of mass loss despite the terminus type of the glaciers.In the current study, the model using the terminus type of the glaciers and the mean elevation of the glaciers explains 76% of fluctuation of mass balance in the Sikkim Himalayan region.
  • Performance evaluation of CLM5.0 in simulating liquid soil water in high mountainous area, Northwest China
    ZHANG Lan-hui, NING Feng-wei, BAI Xu-liang, ZENG Xuan, HE Chan-sheng
    2023, 20(07): 1865-1883.
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    The model performance in simulating soil water content(SWC) is crucial for successfully modeling earth's system, especially in high mountainous areas. In this study, the performance of Community Land Model 5.0(CLM5.0) in simulating liquid SWC was evaluated against observations from nine in-situ sites in the upper reach of the Heihe River Watershed(HRW), Northwest China. The CLM5.0 shows reliable performance in the study area with correlation coefficients(R) ranging between 0.79–0.93, root mean standard errors(RMSE)ranging between 0.044–0.097 m~3/m~3, and the mean bias(BIAS) ranging between-0.084–0.061 m~3/m~3. The slightly worse performance of CLM5.0 than CLM4.5 on alpine meadow and grassland is mainly caused by the revised canopy interception parameterization. The CLM5.0 overestimates interception and underestimates evapotranspiration(ET) on both alpine meadow and grassland during the growth period. The systematical overestimations at all the grassland sites indicate that the underestimation of ET is much larger than the overestimation of interception on grassland during growth period, while the errors of simulated interception and ET are partially canceled out on alpine meadow. Moreover, the underestimation of ET is more responsible for the overestimation of SWC than the overestimation of interception in the high mountainous area. It is necessary to estimate reasonable empirical parameter α(proportion of leaf water collection area) in interception parameterization scheme and further improve the dry surface layerbased soil evaporation resistance parameterization introduced in CLM5.0 in future researches. The performance of CLM5.0 is better under completely frozen stage than thawing stage and freezing stage,because of low variations of liquid SWC caused by extremely low hydraulic conductivity of soils. The underestimation of liquid SWC under frozen state is caused by underestimation of soil temperature, which leads to more ice mass and less liquid water in total water content.
  • Ice flux of alpine glaciers controls erosion and landscape in the Nianbaoyeze Shan, northeastern Tibetan Plateau
    CHEN Xiao-jing, WANG Jie, ZOU Li-yang, YAO Pan, LEI Man-hong, LIAO Jing-sheng
    2023, 20(07): 1884-1899.
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    The evolution of mountainous topography is the result of the interactions of climate, topography, and erosion. Glaciers are one of the most active erosional forces sculpting mountainous regions. However, our ability to understand this erosional force is limited by the controversy regarding the major factors controlling glacial erosion. We selected the Nianbaoyeze Shan, which is occupied by subcontinental glaciers(likely cold-based or polythermal glaciers) in the northeastern Tibetan Plateau, to study how erosion by alpine glaciers sculpts the landscape. We first applied a power law model(y =axb) fit to the cross-profiles of glacial valleys and analyzed the controlling factor of glacial erosion; we then identified the morphometric characteristics of the cirques to analyze the influencing factors, and investigated the development patterns of glacial valleys and cirques. Finally, we used hypsometry and the slopealtitude curves and reconstructed the palaeo-glacier surfaces and palaeo-Equilibrium Line Altitudes(ELAs)to determine if the glacial buzzsaw effect had impacted this glaciated region with subcontinental glaciers. Our findings show that ice flux is the main factor controlling glacial erosion. In this region, decreasing temperatures promote an increase in glacier mean size(i.e., ice flux),which enhances the rate of glacial erosion. Cirque morphology is mainly influenced by aspect and the ELA.The development patterns of glacial valleys and cirques were dominated by a widening process. The ELAs of Marine Isotope Stage(MIS)-3 derived from the cirque floor altitudes or the Accumulation Area Ratio(AAR)and Area-Altitude Balance Ratio(AABR) coincide with the hypsometric maximum and the reduction in slopealtitude curves, which indicates that glacial buzzsaw has impacted this region. Furthermore, the glacial buzzsaw effect has profoundly influenced the mountain heights and topographic evolution in this subcontinental glaciated region.
  • Influence of crack characteristics on the morphological development of Benggang and hydrological processes
    LIU Wei-ping, WANG Shu-han, TIAN Si-wen, OUYANG Guo-quan, HU Li-na, YUAN Zhi-jun
    2023, 20(07): 1900-1910.
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    Benggang is a special type of soil erosion,which widely distributes in the granite residual soil area of southern China. Owing to the influence of local climate and topography, shallow cracks having different morphological characteristics are easily formed on the slope surface. These shallow cracks damage the surface structure of the slope and accelerate water infiltration, making it easier to cause severe soil and water loss. However, the mechanism of Benggang process is still unclear, especially for slopes with different shallow crack characteristics. In this study, granite residual soil was collected from Benngang erosion area in Yudu County, Jiangxi Province, southern China. Three experimental treatments with slope surface crack rates of 0%, 5.23%,and 11.70% were performed. Simultaneous monitoring of moisture content and soil temperature in the slope were carried out during rainfall, and the characteristics of preferential flow were monitored with different crack rates. Morphological development and evolution process of Benggang with different crack rates were studied. Results show that high surface crack rate of the shallow surface on the slope accelerated the development of shallow gully erosion, leading to premature occurrence of gully erosion. As the shallow crack rate increased from 0% to 5.23% and 11.70%, the width-depth ratio of the rills at the slope bottom increased from 0.69 to 1.02 and 1.16, respectively. At the same time, a correlation between moisture and temperature data was observed for the process of water-heat coupled migration. The upper soil temperature of slope decreased quickly due to preferential flow. The simultaneous monitoring of soil moisture and temperature can effectively track preferential flow and indicate the water movement.Temperature data was a more sensitive indicator of the seepage paths of preferential flow compared to moisture data.
  • Patterns of species richness and beta diversity of vascular plants along elevation gradient in Brazilian páramo
    CORDEIRO Anais de Almeida Campos, KLANDERUD Kari, VILLA Pedro Manuel, NERI Andreza Viana
    2023, 20(07): 1911-1920.
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    Understanding the relationships between plant diversity and the environment is an important step towards conservation of species and ecosystems.In this study, we hypothesize that community species richness decreases and species composition change along the elevation gradient, with a greater contribution of species turnover than nestedness to beta diversity. We surveyed plant species in 300 plots(1 m × 1 m) in four elevational bands(2100 m, 2300m, 2500 m, and 2700 m) in the Caparaó National Park, Southeastern Brazil. The samples presented a great number of species(97 spp., 59 genera, 27families), however, 74% of the species were considered rare with their relative abundance being <1%. Among the four bands along the gradient, we detected two distinct communities with few species in common. The transition between the two communities occurred at 2500 m, and this elevation band also had the highest species richness in total. A non-metric multidimensional scaling(NMDS)showed floristic differences between the bands even though they had similar richness. In 89% of the plot pairs, using pairwise comparison of species composition, only half of the species that occurred in one did occur in the other plot. The dissimilarity among the plots and elevational band reflects a significant contribution of spatial species turnover to the species richness and beta diversity on the Caparaó mountain. Beta diversity increased with spatial scale(from plot to elevational-band). The dissimilarity(βSOR=0.907) in the area was due almost exclusively to spatial species turnover(βSIM=0.879),with very low contribution of species nestedness(βSNE=0.028). Our research showed that species richness does not decrease with elevation in the study area, but the floristic composition changes. The clear distinction of species along the gradient show that spatial species turnover is the major diversitygenerating process in the studied area.
  • Assessing the impacts of natural conditions and human activities on terrestrial water storage in Loess Plateau, China
    WANG Cheng-xi, YAN Jian-wu, LIANG Wei, SUN Shao-bo, GOU Fen, LI Xiao-fei, LUO Yuan-yuan, WANG Feng-jiao
    2023, 20(07): 1921-1939.
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    The gravity recovery and climate experiment(GRACE) has emerged as a crucial source of land water storage information in hydrological analysis and research. Numerous factors contribute to regional terrestrial water storage(TWS), resulting in a complex mechanism. In the Loess Plateau region, the continuous alteration of natural conditions and profound impact of human activities have posed a serious threat to the natural ecosystem, leading to an escalating trend of TWS reduction. Addressing the specific analysis of how natural conditions and human activities affect TWS represents a pressing issue. This study employed the residual analysis method to discern the contribution rates of natural conditions and human activities, elucidated the spatial and temporal changes associated with each factor, and ascertained their individual influence. The findings indicated that TWS on the Loess Plateau exhibited a downward trend of-4.89 mm·a~(-1) from 2003 to 2017.The combined effects of climate change and human activities accounted for alterations in water resource reserves across most areas of the Loess Plateau, with human activities predominantly driving these changes.Precipitation emerged as the primary natural factor influencing TWS variations, and NDVI demonstrated a positive feedback effect on TWS at approximately 30%.Substantial spatial disparities in TWS existed within the Loess Plateau, with human activities identified as the primary cause for the decreasing trend. Vegetation restoration plays a positive role in saving water resources in the Loess Plateau to some extent, and vegetation growth exceeding the regional load will lead to water shortage.
  • Impacts of environmental conditions on woody plant diversity, structure and regeneration in forest patches of Guna Mountain: Este District, South Gondar Zone, Ethiopia
    DILNESSA Gashaye, ZERIHUN Woldu, SILESHI Nemomissa, ENYEW Adgo
    2023, 20(07): 1940-1953.
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    Environmental conditions determine woody plant life such as species diversity, structure and regeneration status. This research aimed to assess the impact of environmental conditions on woody plant species diversity, structure and regeneration in forest patches of Guna Mountain: the case of Este District, South Gondar Zone, north-west Ethiopia. A total of 71 square sample plots(400 m~2 each) were established at 10 transects laid in five forest patches of the study area to collect vegetation data including the abundance of species, height and diameter at breast height(DBH). Environmental data including available potassium, available phosphorus, cation exchange capacity, soil texture, electrical conductivity,soil acidity, total nitrogen, organic matter, organic carbon, sodium adsorption ratio, exchangeable sodium percentage, bulk density, aspect, elevation,slope, latitude and longitude data were collected in the same plots. A correlation analysis between vegetation and environmental data was performed using rcorr(x) function in package Hmisc in R Programming Language. The most pronounced impacts were observed in altitude, grazing and pH,positively and silt, sand, electrical conductivity and cation exchange capacity, negatively. In addition,strong and significant impacts on plant structure were also observed due to the variation in soil texture and p H. The difference in aspect, sand and slope also impacted plant regeneration. The study showed that environmental parameters influence the diversity,structure and regeneration of woody plants. These parameters can be considered in the rehabilitation of the vegetation cover and conservation efforts of the rare woody species. Conservation measures that can minimalize the negative influences of environmental conditions can be applied through collaboration with communities around the forest patches.
  • Inconsistent increasing of climate potential productivity resulting from global warming and land use transitions in the Dongting Lake Basin, from 2000 to 2020
    WANG Ji-ren, ZHENG Jian, SU Jian, ZHENG Bo-hong, SUN Zhao-qian
    2023, 20(07): 1954-1967.
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    In the face of global warming and increasing impervious surfaces, quantifying the change of climate potential productivity(CPP) is of great significance for the food production planning.Targeting the Dongting Lake Basin, which is a key area for food production in China, this paper uses meteorological data, as well as Climate Change Initiative Land Cover, and Shuttle Radar Topography Mission digital elevation model to investigate the CPP and its changes from 2000 to 2020. The suitability of land for cultivation(SLC), and the land use/land cover change(LUCC) are also considered. The results showed that the CPP varied from 9,825 to 20,895 kg ha~(-1). Even though the newly added impervious surfaces indirectly resulted in the decrease of CPP by of 9.81×10~8 kg, overall, the CPP increased at an average rate of 83.7 kg ha~(-1) a~(-1). Global warming is the strongest driver behind CPP increase, and CPP has played an important role in the conversions between cultivated land and other land types. The structure of land types tends to be optimized against this challenge.
  • Evaluation of the treatment effect of rear slope cutting on hydrodynamic pressure landslides: A case study
    WANG Li, HUANG Jun-jie, CHEN Yong, WANG Shi-mei, FAN Zhi-hong, GUO Fei, LI Xiao-wei
    2023, 20(07): 1968-1983.
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    After the impoundment of the Three Gorges Reservoir, some huge ancient landslides were reactivated and deformed,showing typical hydrodynamic pressure landslide characteristics. The Baishuihe landslide was a typical hydrodynamic pressure landslide. The management department conducted slope cutting treatments from 2018 to 2019.To evaluate the treatment effect of rear slope cutting,this study analyzed the data of the surface deformation survey and field monitoring over the past 20 years and the characteristics of the reservoir water-triggered Baishuihe landslide deformation, and calculated the seepage field, displacement field, and stability coefficient before and after landslide treatment. The results showed that the deformation of the Baishuihe landslide was primarily related to a decrease in the reservoir water level. Owing to the poor permeability of the landslide soil, the decrease in the reservoir water level produced a seepage force pointing to the outside of the landslide body, leading to the step deformation of the landslide displacement. The landslide was treated by rear slope cutting, and the “step”deformation of the landslide disappeared after treatment. The hydrodynamic pressure caused by the change in reservoir water after cutting the slope did not disappear. However, as the slope cutting greatly reduced the overall sliding force of the landslide, its stability was greatly improved. Notably, high stability can still be ensured under extreme rainfall after treatment. Slope cutting is effective for treating hydrodynamic pressure landslides. This study can provide effective technical support for the treatment of reservoir landslides.
  • Deep-seated rock fracture of valley slopes in China: A review
    PENG Yi, ZHAO Qi-hua, HAN Gang, CHEN Yu-shu
    2023, 20(07): 1984-2002.
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    Deep-seated rock fractures(referred to as DSRF hereafter) in valley slopes are uncommon geological phenomena that challenge our previous understanding of slope unloading processes. These fractures weaken the strength and integrity of the rock mass, potentially forming unstable block boundaries with significant volume, thereby affecting the stability of slopes, chambers, and dam abutments.DSRF has emerged as a critical environmental and engineering geological issue that hinders large-scale projects in deep canyon areas. Despite the attention and practical treatment given to DSRF in engineering practice, theoretical research on this topic still lags behind the demands of engineering applications. To garner widespread attention and promote the resolution of DSRF-related problems, this review aims to redefine DSRF through comprehensive data collection and analysis, engineering geological analogies, and field investigations, and provide a summary and analysis of the research progress on DSRF, along with future research directions. The study defines DSRF as the intermittent tension cracks or relaxation zones within a slightly weathered or fresh, and intact or relatively intact rock mass distributed below the surface unloading zones of a deep canyon slope, and should be distinguished from "loose rock mass" and "deep-seated gravitational slope deformations". The article provides an overview of the development and distribution, rupture characteristics, and genesis mechanism of DSRF. It proposes that DSRF is formed based on the fluvial deviation-undercutting evolution mode, wherein the energy accumulated in the rock mass is violently released when the river further down cuts the slope after the rock mass has undergone cyclical loadingunloading. However, further research is necessary to establish a comprehensive database for DSRF, refine exploration techniques, understand evolutionary processes, develop engineering evaluation methods,and predict the distribution of DSRF.
  • Hierarchical pattern recognition of landform elements considering scale adaptation
    XU Yue-xue, ZHU Hong-chun, LI Jin-yu, ZHANG Sheng-jia
    2023, 20(07): 2003-2014.
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    Landform elements with varying morphologies and spatial arrangements are recognized as feature indicator of landform classification and play a critical role in geomorphological studies. Differential geometry method has been extensively applied in prior landform element research, while its efficacy in differentiating similar morphological characteristics remains inadequate to date. To reduce reliance on geomorphometric variables and increase awareness of landform patterns, geomorphons method was generated in previous study corresponding to specific landform reclassification map based on lookup table.Besides, to address the problem of feature similarity,hierarchical classification was proposed and effectively utilized for terrain recognition through the analytical strategy of fuzzy gradient features. Thus,combining the advantages of these two aspects, a hierarchical framework was proposed in this study for landform element pattern recognition considering the morphology and hierarchy factors. First, the local triplet patterns derived from geomorphons were enhanced by setting the flatness threshold, and subsequently adopted for the primary landform element recognition. Then, as geomorphic units with the same morphology possess different spatial analytical scales, the unidentified landform elements under the principle of scale adaptation were determined by calculating the spatial correlation and entropy information. To ensure the effectiveness of this proposed method, the sampling points were randomly selected from NASADEM data and then validated against a real 3D terrain model.Quantitative results of landform element pattern recognition demonstrate that our approach can reach above 77% average accuracy. Additionally, it delineates local details more effectively than geomorphons in visual assessment, resulting in a 7%accuracy improvement in overall scale.
  • Peak extraction and classification from digital elevation models based on the relationship between morphological characteristics and spatial position
    ZHAO Ming-wei, FANG Yue, YANG Can-can, JU Xiao-xiao, HUANG Xiao-li, JIANG Ling, WANG Chun, XU Yan
    2023, 20(07): 2015-2028.
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    A peak is an important topographic feature crucial in quantitative geomorphic feature analysis,digital geomorphological mapping, and other fields.Most peak extraction methods are based on the maximum elevation in a local area but ignore the morphological characteristics of the peak area. This paper proposes three indices based on the morphological characteristics of peaks and their spatial relationship with ridge lines: convexity mean index(CM-index), convexity standard deviation(CSD-index), and convexity imbalance index(CIBindex). We develop computation methods to extract peaks from digital elevation model(DEM).Subsequently, the initial peaks extracted by neighborhood statistics are classified using the proposed indices. The method is evaluated in the Qinghai Tibet Plateau and the Loess Plateau in China.An ASTER Global DEM(ASTGTM2 DEM) with a grid size of 30 m is chosen to assess the suitability of the proposed mountain peak extraction and classification method in different geomorphic regions. DEM data with grid sizes of 30 m and 5 m are used for the Loess Plateau. The mountain peak extraction and classification results obtained from the different resolution DEM are compared. The experimental results show that:(1) The CM-index and the CSDindex accurately reflect the concave or convex morphology of the surface and can be used as supplements to existing surface morphological indices.(2) The three indices can identify pseudo mountain peaks and classify the remaining peaks into single ridge peak(SR-Peak) and multiple ridge intersection peak(MRI-Peak). The visual inspection results show that the classification accuracy in the different study areas exceeds 75%.(3) The number of peaks is significantly higher for the 5 m DEM than for the 30 m DEM because more peaks can be detected at a finer resolution.
  • Tunnelling performance prediction of cantilever boring machine in sedimentary hard-rock tunnel using deep belief network
    SONG Zhan-ping, CHENG Yun, ZHANG Ze-kun, YANG Teng-tian
    2023, 20(07): 2029-2040.
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    Evaluating the adaptability of cantilever boring machine(CBM) through in-depth excavation and analysis of tunnel excavation data and rock mass parameters is the premise of mechanical design and efficient excavation in the field of underground space engineering. This paper presented a case study of tunnelling performance prediction method of CBM in sedimentary hard-rock tunnel of Karst landform type by using tunneling data and surrounding rock parameters. The uniaxial compressive strength(UCS),rock integrity factor(Kv), basic quality index([BQ]),rock quality index RQD, brazilian tensile strength(BTS) and brittleness index(BI) were introduced to construct a performance prediction database based on the hard-rock tunnel of Guiyang Metro Line 1 and Line 3, and then established the performance prediction model of cantilever boring machine. Then the deep belief network(DBN) was introduced into the performance prediction model, and the reliability of performance prediction model was verified by combining with engineering data. The study showed that the influence degree of surrounding rock parameters on the tunneling performance of the cantilever boring machine is UCS > [BQ] > BTS >RQD > Kv > BI. The performance prediction model shows that the instantaneous cutting rate(ICR) has a good correlation with the surrounding rock parameters, and the predicting model accuracy is related to the reliability of construction data. The prediction of limestone and dolomite sections of Line 3 based on the DBN performance prediction model shows that the measured ICR and predicted ICR is consistent and the built performance prediction model is reliable. The research results have theoretical reference significance for the applicability analysis and mechanical selection of cantilever boring machine for hard rock tunnel.
  • Load laws of composite lining in mountain tunnel model tests and numerical simulation validation
    ZHOU Jian, YANG Xin-an, CHU Zheng
    2023, 20(07): 2041-2057.
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    Currently, model tests are increasingly being used to simulate the construction of mountain tunnels, but the support structure of the model tests does not show the composite lining, and the force laws of the composite lining are not yet clear. In this research, the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation factors. The test results reveal that:(1) The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding rock. Correspondingly,for Class Ⅲ surrounding rock and better quality of surrounding rock, the primary support can lag behind the excavation face a certain distance.(2) The axial forces of the bolts tend to rise with concentration of 0.4 kN-0.7 kN after the secondary lining was installed.(3) With or without two to three excavation cycles delayed, the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%. Finally, the numerical simulation verifies the feasibility of the model tests.
  • Failure mechanism and control countermeasures of surrounding rock at deep large section chamber intersection in the Wanfu Coal Mine
    SUN Xiao-ming, QI Zhen-min, ZHANG Yong, MIAO Cheng-yu, ZHAO Cheng-wei, HE Man-chao
    2023, 20(07): 2058-2075.
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    In order to solve the problem of large deformation at the intersection of deep large section soft rock roadway, this paper takes the intersection of kilometer-deep roadway in the Wanfu Coal Mine as an engineering example and applies Negative Poisson's Ratio(NPR) steel anchor cable in roadway support for the first time. By combining numerical simulation indoor test, theoretical analysis and field test, the deformation mechanism of surrounding rock at the intersection of deep-buried roadway was analyzed, and the control strategy with micro NPR steel anchor cable as the core was put forward.Through numerical simulation, the numerical analysis model of roadway intersection with different intersection angles and excavation sequence was constructed, and the impact of two key variables of rake angle and excavation sequence on the stability of surrounding rock at roadway intersection was studied. The optimal dip angle is 90° and the optimal excavation sequence was determined as pump house-pump house passage-substation. The mechanical properties of the micro-NPR steel anchor cable were studied through the static tensile test in the laboratory. The results showed that the micro-NPR steel anchor cable showed high constant resistance,uniform tensile, no yield platform, and no obvious necking phenomenon during breaking. Through theoretical derivation, it was calculated that the vertical stress of roadway intersection is 45 MPa, and the bearing capacity of superposed arch composed of micro NPR steel anchor cable is 1257 kN, which is enough to guarantee the overall stability of intersection. Support application test and monitoring were carried out on site, and it was verified that the combined support strategy of short and long micro NPR steel anchor cable has a good control effect on large deformation of surrounding rock at intersection,which provides a new support material and support means for the safety and stabilization control of surrounding rock at intersection.
  • Optimization of anchorage support parameters for soft rock tunnel based on displacement control theory
    LI Gan, MA Wei-bin, YU Chang-yi, TAO Zhi-gang, WANG Feng-nian
    2023, 20(07): 2076-2092.
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    In the construction of a soft rock tunnel, it is critical to accurately estimate the pre-stressed anchor support parameters for surrounding rock reinforcement; otherwise, engineering disasters may occur. This paper presents a support parameter selection method that aims to allow deformation as a control objective, which was applied to the tunnel located in Muzailing Highway, Min County, Dingxi City, Gansu Province, China. Through theoretical analysis, we have identified five factors that influence pre-stressing anchorages. The selection of mechanical parameters for the rock mass was carried out using an inverse analysis method. Compared with the measured data, the maximum displacement error of the numerical simulation results was only 0.07 m.The length of anchor cable, circumferential spacing of anchor cable, longitudinal spacing, and pre-stress index are adopted as the input parameters for the support vector machine neural network model based on particle swarm optimization(PSO-LSSVM).Besides, the vault subsidence and the maximum deformation of surrounding rock are considered as output values(performance indices). The goodness of fit between the predicted values and the simulated values exceeds 0.9. Finally, all support parameters within the acceptable deformation range are calculated. The optimal support variables are derived by considering the construction cost and duration.The field application results show that it is feasible to construct the sample database utilizing the numerical simulation approach by taking the displacement as the control target and using the neural network to specify the appropriate support parameters.
  • Seismic dynamic stability of double-slider rock slopes containing tension cracks
    ZHU Chen-hao, ZHAO Lian-heng, HU Shi-hong, ZUO Shi, YU Cheng-hao
    2023, 20(07): 2093-2106.
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    Earthquakes have significant impact on rock slopes, thus studying the seismic stability of double-slider rock slopes containing tension cracks is crucial. We proposed an analysis method on the seismic dynamic slope stability. This method utilizes discrete Fourier transform to decompose real earthquake waves into a combination of harmonic waves. These waves are then used in conjunction with the pseudo-dynamic method and safety factor calculation formula to compute the safety factor. This approach accurately captures the influence of seismic time history characteristics on the dynamic stability of double-slider rock slopes containing tension cracks.The minimum safety factor in the obtained time history curves of the safety factor reflects the most unfavorable state of the slopes under seismic effects.Quantitative analysis is conducted using six sets of actual earthquake ground motion data obtained from the Pacific Earthquake Engineering Research Center's NGAWest2 ground-shaking record database. The conclusions are as follows:(1) There is an inverse correlation between the average seismic acceleration amplitude and the minimum safety factor.Conversely, the seismic acceleration amplitude standard deviation shows a positive correlation with the minimum safety factor. The global sensitivity of geometric parameters in the slope model is higher than other influencing factors.(2) The proposed dynamic stability analysis method can capture the dynamic characteristics of earthquakes, emphasizing the minimum safety factor of the slope in the seismic time history as a stability indicator. In contrast, the pseudo-static method may yield unsafe results.(3) A safety factor expression considering hydrostatic pressure is proposed. A negative correlation was observed between the height of the water level line and the minimum safety factor.