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过刊目录

  • 2023年, 20卷, 第04期
    刊出日期：2024-06-19
      
  • 全选
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  • Morphodynamics and sediment connectivity index in an unmanaged,debris-flow prone catchment: a through time perspective
    Loris TORRESANI, Guillaume PITON, Vincenzo D’AGOSTINO
    2023, 20(04): 891-910.
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    Torrential processes are among the main actors responsible for sediment production and mobility in mountain catchments. For this reason, the understanding of preferential pathways for sediment routing has become a priority in hazard assessment and mitigation. In this context, the sediment Connectivity Index(IC) enables to analyse the existing linkage between sediment sources and the selected target(channel network or catchment outlet).The IC is a grid-based index that allows fast computation of sediment connectivity based on landscape information derived from a single Digital Terrain Model(DTM). The index computation is based on the log-ratio between an upslope and a downslope component, including information about drainage area, slope, terrain roughness, and distance to the analysis target(e.g. outlet). The output is a map that highlights the degree of structural connectivity of sediment pathways over analysed catchments. Until now, these maps are however rarely used to help defining debris-flow hazard maps, notably due to a lack of guidelines to interpret the IC spatial distribution. This paper proposes an exploitation procedure along profiles to extract more information from the analysis of mapped IC values. The methodology relies on the analysis of the IC and its component variables along the main channel profile,integrated with information about sediment budgeting derived from Difference of DEMs(DoD).The study of connectivity was applied in the unmanaged sub-catchment(without torrent control works) of the Rio Soial(Autonomous Province of Trento – NE Italy) to understanding the geomorphic evolution of the area after five debris flows(in ten years) and the related changes of sediment connectivity. Using a recent DTM as validation, we demonstrated how an IC analysis over the older DTM can help predicting geomorphic changes and associated hazards. The results show an IC aptitude to capture geomorphic trajectories, anticipate debris flow deposits in a specific channel location, and depict preferential routing pathways..
  • Sentinel-1 In SAR observations and time-series analysis of co- and postseismic deformation mechanisms of the 2021 Mw 5.8 Bandar Ganaveh Earthquake, Southern Iran
    Reza SABER, Veysel ISIK, Ayse CAGLAYAN, Marjan TOURANI
    2023, 20(04): 911-927.
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    In the past two decades, because of the significant increase in the availability of differential interferometry from synthetic aperture radar and GPS data, spaceborne geodesy has been widely employed to determine the co-seismic displacement field of earthquakes. On April 18, 2021, a moderate earthquake(Mw 5.8) occurred east of Bandar Ganaveh, southern Iran, followed by intensive seismic activity and aftershocks of various magnitudes. We use two-pass D-InSAR and Small Baseline Inversion techniques via the LiCSBAS suite to study the coseismic displacement and monitor the four-month post-seismic deformation of the Bandar Ganaveh earthquake, as well as constrain the fault geometry of the co-seismic faulting mechanism during the seismic sequence. Analyses show that the co-and postseismic deformation are distributed in relatively shallow depths along with an NW-SE striking and NE dipping complex reverse/thrust fault branches of the Zagros Mountain Front Fault, complying with the main trend of the Zagros structures. The average cumulative displacements were obtained from-137.5 to +113.3 mm/yr in the SW and NE blocks of the Mountain Front Fault, respectively. The received maximum uplift amount is approximately consistent with the overall orogen-normal shortening component of the Arabian-Eurasian convergence in the Zagros region. No surface ruptures were associated with the seismic source; therefore, we propose a shallow blind thrust/reverse fault(depth ～10 km) connected to the deeper basal decollement fault within a complex tectonic zone, emphasizing the thin-skinned tectonics.
  • Rapid prediction models for 3D geometry of landslide dam considering the damming process
    WU Hao, NIAN Ting-kai, SHAN Zhi-gang, LI Dong-yang, GUO Xing-sen, JIANG Xian-gang
    2023, 20(04): 928-942.
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    The geometry of a landslide dam plays a critical role in its stability and failure mode, and is influenced by the damming process. However, there is a lack of understanding of the factors that affect the 3D geometry of a landslide dam. To address this gap,we conducted a study using the smoothed particle hydrodynamics numerical method to investigate the evolution of landslide dams. Our study included 17 numerical simulations to examine the effects of several factors on the geometry of landslide dams,including valley inclination, sliding angle, landslide velocity, and landslide mass repose angle. Based on this, three rapid prediction models were established for calculating the maximum height, the minimum height, and the maximum width of a landslide dam.The results show that the downstream width of a landslide dam remarkably increases with the valley inclination. The position of the maximum dam height along the valley direction is independent of external factors and is always located in the middle of the landslide width area. In contrast, that position of the maximum dam height across the valley direction is significantly influenced by the sliding angle and landslide velocity. To validate our models, we applied them to three typical landslide dams and found that the calculated values of the landslide dam geometry were in good agreement with the actual values. The findings of the current study provide a better understanding of the evolution and geometry of landslide dams, giving crucial guidance for the prediction and early warning of landslide dam disasters.
  • Risk assessment and landslide prevention design using numerical modelling——A case study in Qingliu, China
    LI Cong-jiang, HU Yu-xiang, JIANG Nan, LI Hai-bo, ZHOU Jia-wen
    2023, 20(04): 943-961.
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    Numerous Quaternary deposits are existed in the mountainous areas of Southwest China,especially in the transition zone between the QinghaiTibet Plateau and the Sichuan Basin, where strong tectonic movements and frequent climatic changes increase the potential landslides. The possible deformation and failure process of potential landslides and their impacts on the surrounding environment are important research topics. Field investigation and monitoring indicate that the Qingliu landslide in Xiameng town, Li County, Sichuan Province, China has been continuously deforming since August 2020. The deformation zone has a maximum deformation depth of approximately 18.9m, a total area of 54,628 m~2, and a volume of 34.0×10~4 m~3, which seriously threatens infrastructure projects and dwellings. As a result, understanding the Qingliu landslide evolution process, assessing the hazard risk, and planning disaster prevention measures are of great significance for reducing disaster loss. In this study, the mass movement process and hazard risk of the Qingliu landslide are evaluated, and the effects of different prevention measures are compared and discussed. By using the depth-integrated method, the mass movement of the Qingliu landslide is analyzed. The numerical simulation results indicate that the maximum velocity of the Qingliu landslide is approximately 37.5 m/s,and the duration of the landslide is approximately 90s. The simulated landslide can eventually form a deposited mass with a maximum deposit thickness of 19.4 m and an area of approximately 60,168.3 m~2,thereby blocking the river and burying dwellings.Furthermore, a risk assessment of the Qingliu landslide under different forms of protection measures is also produced and discussed by considering the hazard level and economic vulnerability level of the affected area. Setting three layers of anti-slide piles on the deformation zone to reduce the hazard risk of the Qingliu landslide is a better choice. Our results may be useful for planning prevention measures and improving disaster emergency response systems.
  • Effects of sand sedimentation and wind erosion around sand barrier: Numerical simulation and wind tunnel test studies
    ZHANG Kai, ZHANG Hai-long, DENG Yu-hui, QU Jian-jun, WANG Zheng-hui, LI Sheng
    2023, 20(04): 962-978.
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    Based on numerical simulations, this study highlights the sedimentation and erosion problems around a sand barrier through the relationship between the shear stress of the surface around the sand barrier and the critical shear stress of sand grains. The numerical simulation results were verified using data measured by the wind tunnel test.The results showed that when the porosity was the same, the size and position of the vortex on the leeward side of the sand barrier were related to the inlet wind speed. As the wind speed increased, the vortex volume increased and the positions of the separation and reattachment points moved toward the leeward side. When the porosity of the sand barrier was 30%, the strength of the acceleration zone above the sand barrier was the highest, and the strength of the acceleration zone was negatively correlated with the porosity. Sand erosion and sedimentation distance were related to wind speed.With an increase in wind speed, the sand grain forward erosion or reverse erosion areas on the leeward side of the sand barrier gradually replaced the sedimentation area. With an increase in porosity,the sand sedimentation distance on the leeward side of the sand barrier gradually shortened, and the sand erosion area gradually disappeared. The sand sedimentation distance on the leeward side of the sand barrier with 30% porosity was the longest. The numerical simulation results were in good agreement with the wind tunnel test results. Based on the sand erosion and sedimentation results of the numerical simulation and wind tunnel test, when the porosity was 30%, the protection effect of the High Density Polyethylene(HDPE) board sand barrier was best.
  • Comparison of LR, 5-CV SVM, GA SVM, and PSO SVM for landslide susceptibility assessment in Tibetan Plateau area, China
    ZHANG Ying-bin, XU Pei-yi, LIU Jing, HE Jian-xian, YANG Hao-tian, ZENG Ying, HE Yun-yong, YANG Chang-feng
    2023, 20(04): 979-995.
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    The applicability of statistics-based landslide susceptibility assessment methods is affected by the number of historical landslides.Previous studies have proposed support vector machine(SVM) as a small-sample learning method.However, those studies demonstrated that different parameters can affect model performance. We optimized the SVM and obtained models as 5-fold cross validation(5-CV) SVM, genetic algorithm(GA)SVM, and particle swarm optimization(PSO) SVM.This study compared the prediction performances of logistic regression(LR), 5-CV SVM, GA SVM, and PSO SVM on landslide susceptibility mapping, to explore the spatial distribution of landslide susceptibility in the study area in Tibetan Plateau,China. A geospatial database was established based on 392 historical landslides and 392 non-landslides in the study area. We used 11 influencing factors of altitude, slope, aspect, curvature, lithology,normalized difference vegetation index(NDVI),distance to road, distance to river, distance to fault,peak ground acceleration(PGA), and rainfall to construct an influencing factor evaluation system. To evaluate the models, four susceptibility maps were compared via receiver operating characteristics(ROC)curve and the results showed that prediction rates for the models are 84%(LR), 87%(5-CV SVM), 85%(GA SVM), and 90%(PSO SVM). We also used precision,recall, F1-score and accuracy to assess the quality performance of these models. The results showed that the PSO SVM had greater potential for future implementation in the Tibetan Plateau area because of its superior performance in the landslide susceptibility assessment.
  • Abrupt change of winter temperature over the Mongolian Plateau during 1961-2017
    XIA Ying-ying, CHUN Xi, DAN Dan, LIU Hong-yu, ZHOU Hai-jun, WAN Zhi-qiang
    2023, 20(04): 996-1009.
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    Studying the abrupt change of winter temperature(ACWT) over the Mongolian Plateau(MP, including Inner Mongolia Autonomous Region and State of Mongolia) is of great significance for understanding the spatiotemporal distribution of temperature and the mechanism of global climate change. Monthly temperature data during 1961–2017was collected, and the abrupt change point was determined by the Mann–Kendall test and sliding ttest, to analyze the characteristics and causes of ACWT. The results showed that(a) The winter temperature has rapidly increased with a trend of 0.41℃/10a, which was significantly higher than that of the rest area of Chinese mainland, indicating that climate change in the MP was more sensitive to global warming.(b) The abrupt change point occurred in 1988, with temperature of-15.5 ℃ and-14.1 ℃ before and after abrupt change, respectively. The ACWT in 50°N was 1–3 years later than that in 40°N, and the isotherms of different temperatures moved northward by 10–200 km, especially-16℃ isotherms moved approximately 200 km northward after 1988.(c) The Arctic Oscillation(AO) and Mongolian High(MH)anomaly affects winter temperature over the MP.When the AO is unusually strong, the MH and East Asian winter monsoon are weak, and southerly winds prevail in most regions, which is not conducive to the cold air developing southward, leading to higher winter temperature in the MP. Overwise, abnormally northerly winds prevail and temperature is low.Meanwhile, the abrupt change time of AO occurred in 1987 before winter temperature. It shows that the AO indirectly causes winter temperatures to rise by influencing the MH and is also the main driving factor of ACWT.
  • Hydroclimatic variations in the Tianshan Mountains based on grain size and geochemistry of core sediments since ～1490 CE
    LAN Bo, XU Wen-feng, YANG Yun-peng, CHEN Xiang-le, LIU Zheng-xue, ZHANG Dong-liang
    2023, 20(04): 1010-1025.
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    Numerous studies have focused on modern hydroclimate and the modulated mechanisms in the Tianshan Mountains(TMs), arid central Asia.However, the detailed information of hydroclimatic processes beyond the instrumental period is still scarce. This paper reconstructed a hydrology history from core sediments of the Dalongchi Lake in the Tianshan Mountains. The comparability between endmembers(EMs) of grain size and ICP-AES based geochemical elements in the lake sediments highlighted their availability for hydrological reconstructions. Hydrodynamic forces(EM1, EM4,Ti/Al and Li/Al), chemical weathering intensity [(Mg+Ca+K)/Al], salinity proxy(Mg/Ca) and redoxsensitive proxy(Fe/Mn) highly correlated with the first principal component(P<0.01), whereas paleoproductivity proxies(TN, TOC, Ba/Al, Zn/Al and Cu/Al) and C/N showed high loadings on the second principal component(P<0.05). The inferred hydrology progress was nonlinearly responded to temperature, precipitation and climate-dictated glaciers. Specifically, the water level didn't always covary with the humidity because of glaciers. The maximum water level was the comprehensive result of glaciers melting and high humidity around 1830 CE.Thereafter, water level continually decreased with declining moisture at high temperature, implying a limited buffering capacity of glaciers in the Dalongchi Lake basin. EM3-indicated eolian activity intensity was caused by the behaviors of Siberian High because the latter intensified surface wind and the dust transportation. The hydrothermal patterns were characterized by warm/dry and cold/wet alternations in a long run although warm/wet pattern was identified from a short-term view.
  • Revisiting the determination of Mount Olympus Height (Greece)
    Dimitrios AMPATZIDIS, Georgios MOSCHOPOULOS, Antonios MOURATIDIS, Michael STYLLAS, Alexandros TSIMERIKAS, Vasileios-Klearchos DELIGIANNIS, Nikolaos VOUTSIS, Triantafyllia-Maria PERIVOLIOTI, Georgios S.VERGOS, Alexandra PLACHTOVA
    2023, 20(04): 1026-1034.
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    The present study deals with the determination of Mount Olympus summit(Mytikas),exploiting modern observations such as Global Navigation Satellite Systems(GNSS) and existing geodetic information. The last official Olympus height determination goes back 102 years by the Swiss surveyor M. Kurz. Since then, only unofficial measurement campaigns have taken place. There is a variety of released heights, which range from 2917 to 2919 meters. In September and October of 2022, we conducted a GNSS campaign, focusing on the area of highest Olympus peaks. Employing precise GNSS measurements(accuracy of 1-3 cm), in conjunction with height information from Greece's National Triangulation Network(5-10 cm accuracy) and an appropriate, recent geoid model(5-6 cm accuracy),we estimate through the so-called GNSS-levelling, the height of Olympus to 2917.727 m with respect to Greece's officially accepted mean sea level and 2918.390 m with respect to the global vertical datum.Our estimation of Olympus highest peak shows remarkable consistency at the level of 12.8 cm to that of M. Kurz in 1921.
  • Regional differences in gully network connectivity based on graph theory: a case study on the Loess Plateau, China
    CHENG Jian-hua, LUO Lan-hua, LI Fa-yuan, LIU Lu-lu, CUI Ling-zhou
    2023, 20(04): 1035-1050.
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    Material exchange frequently occurs in gullies, and thus the relationship between a gullynetwork structure and sediment transport potential has attracted considerable interest. However,previous researches ignored the difficulty of material transport from sources to sinks, and did not quantify the connectivity of a network structure. In this study,we used a graph model structure to model gully networks of six typical sample areas in the Loess Plateau of China and quantified gully network connectivity using four indexes: average node strength, accessibility from sources to sinks, potential flow, and network structural connectivity index.Results show that:(1) Reflected by different quantitative indexes, the trends of gully network connectivity in different regions are similar. From north to south, the connectivity of a sample area first increases and then decreases.(2) The more mature gullies have stronger network connectivity. Small resistance is conducive to material transport in the gullies.(3) The node connectivity index of the gully network shows a significant aggregation distribution in space, and node connectivity on the main channel is often stronger than that on the branch trench.These results not only deepen the understanding of the process and mechanism of loess gully geomorphic development and evolution but also provide a reference for geomorphic studies.
  • Estimation of actual carbon dioxide removal in burned forests using satellite data: A case study in South Korea
    Hanna LEE, Gihong KIM
    2023, 20(04): 1051-1060.
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    With the increasing impact of climate change, carbon emissions and removals have become major issues. Forests are major carbon pools, and forest fires are an essential part of the carbon cycle.This study introduces a model for estimating the detailed actual CO_2 removal in burned forests using burn severity and tree survivability. Actual CO_2removal was estimated from empirical yield tables without using the standard carbon removal provided by the national inventory. The primary CO_2calculation method followed the guidelines of the International Panel on Climate Change. The burn severity was mapped using Sentinel-2 multispectral instrument data, and the survivability of each forest type was estimated according to burn severity. The survivability was applied to the pre-fire CO_2 removal of each forest to estimate post-fire CO_2 removal. In our case study, the burned forest area was 1,034 ha,and the CO_2 removal before the fire was 8,615.3t/year. After the fire, removal decreased by 81.2% to 1,618.4 t/yr. In particular, the decrease in coniferous forests was high, more than 86%. The lack of survivability data on burned trees was a major limitation of our study. Systematically accumulating field monitoring data of post-fire forests will be necessary for future research and could serve as a reference for devising immediate countermeasures against forest fires.
  • Source apportionment of heavy metals in soils around a coal gangue heap with the APCS-MLR and PMF receptor models in Chongqing, southwest China
    MA Jie, SHEN Zhi-jie, WANG Sheng-lan, DENG Li, SUN Jing, LIU Ping, SHE Ze-lei
    2023, 20(04): 1061-1073.
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    This study studied the characteristics and source apportionment of heavy metal pollution in the agricultural soil surrounding a gangue coal heap in Chongqing, China by using absolute principal component scores-multiple linear regression(APCSMLR) model and positive matrix factorization(PMF)model. The applicability of the models was compared in the assessment of source apportionment. The results showed that the average contents of Cd, Hg,As, Pb, Cr, Cu, Ni, and Zn in the surface soil were 0.46, 0.14, 9.66, 31.2, 127, 95.6, 76.0, and 158 mg/kg,respectively. Combined with the spatial distribution and correlation analyses, the results of source apportionment were consistent for both the APCSMLR and PMF models. Cd, Hg, As, and Pb were mainly affected by the gangue heap accumulation,with respective contributions of 74.6%, 79.4%, 69.1%,and 67.2% based on the APCS-MLR model and respective contributions of 69.7%, 60.7%, 57.4%, and 41.9% based on the PMF model. Ni and Zn were mainly affected by industrial and agricultural activities, while Cr and Cu were mainly affected by natural factors. The results of the source apportionment were approximately consistent between the APCS-MLR and PMF models. The combined application of the two receptor models can make the results of source apportionment more comprehensive, accurate, and reliable.
  • Assessment of future Antarctic amplification of surface temperature change under different Scenarios from CMIP6
    ZHU Jiang-ping, XIE Ai-hong, QIN Xiang, XU Bing
    2023, 20(04): 1074-1089.
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    Global warming may result in increased polar amplification, but future temperature changes under different climate change scenarios have not been systematically investigated over Antarctica. An index of Antarctic amplification(AnA) is defined, and the annual and seasonal variations of Antarctic mean temperature are examined from projections of the Coupled Model Intercomparison Project Phase 6(CMIP6) under scenarios SSP119, SSP126, SSP245,SSP370 and SSP585. AnA occurs under all scenarios,and is strongest in the austral summer and autumn,with an AnA index greater than 1.40. Although the warming over Antarctica accelerates with increased anthropogenic forcing, the magnitude of AnA is greatest in SSP126 instead of in SSP585, which may be affected by strong ocean heat uptake in high forcing scenario. Moreover, future AnA shows seasonal difference and regional difference. AnA is most conspicuous in the East Antarctic sector, with the amplification occurring under all scenarios and in all seasons, especially in austral summer when the AnA index is greater than 1.50, and the weakest signal appears in austral winter. Differently, the AnA over West Antarctica is strongest in austral autumn. Under SSP585, the temperature increase over the Antarctic Peninsula exceeds 0.5℃ when the global average warming increases from 1.5℃ to 2.0℃ above preindustrial levels, except in the austral summer, and the AnA index in this region is strong in the austral autumn and winter. The projections suggest that the warming rate under different scenarios might make a large difference to the future AnA.
  • Population dynamics and protection strategies of Litsea coreana Levl. var. sinensis with Guizhou Province in China as an example
    YUAN Gang-yi, GUO Qi-qiang, XIE Na, ZHANG Ya-qin, LUO Si-qiong, GUI Qin, YAO Shan
    2023, 20(04): 1090-1101.
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    Studying the dynamics of plant populations is crucial to the conservation and management of endangered plants. The diameter at breast height(DBH), tree height, crown width, and environmental factors of a total of 15 plots in five populations in Guizhou Province, China were measured in this study. The method of substituting diameter at breast height for age was used to divide the population into 7 age classes. The age structure,static life table, and relationship between the population characteristics and environmental factors of the Litsea coreana Levl. var. sinensis population were studied. Moreover, the time series model was used to predict the population dynamics. Results showed that the age structure of population in Zhengan County(Population ZA) had an inverted Jshape with abundant seedlings and insufficient middle-aged and elderly individuals. The age structures of populations in Daozhen County(Population DZ), Kaiyang County(KY), Meitan County(Population MT), and Xishui County(Population XS) were spindle-shaped with few young individuals and many middle-aged and elderly individuals. The mortality rate of each population fluctuated with the increase in age class, and the populations were extremely unstable. The survival curve was close to the Deevey III type, and the degree of deviation was related to the lack of young individuals. After the age stages II, IV, and VI, the number of aged plants in the different populations initially increased then decreased, and population stability was difficult to maintain. Redundancy analysis showed that the DBH, tree height and crown width of the population decreased with the increase of annual mean temperature, and the population density was restricted by soil nutrient conditions to a certain extent. The results of this work provide scientific basis for the conservation and sustainable utilization of natural populations of L. coreana var. sinensis in Guizhou Province, China.
  • The lateral pressure coefficient at rest of expansive soils in landfill at various vertical stresses and moisture contents
    ZHOU Zhen-hua, KONG Ling-wei, SUN Zhi-liang, LI Tian-guo, YAN Jun-biao
    2023, 20(04): 1102-1117.
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    When expansive soils in the original location are artificially transferred to landfill in different seasons, and subject to engineering activities afterwards, the corresponding deformation and stability of retaining structures become unpredictable.This necessitates the determination of lateral pressure coefficient at rest(k0 value) for expansive soils in landfill. Considering compaction, excavation of expansive soils, as well as construction of landfill in different seasons, series of stepwise loading and unloading consolidation tests at various moisture contents were carried out in this work to explore the evolution characteristics of k_0 value and assess the dependence of k_0 value on vertical stress and moisture content. Besides, scanning electron microscope(SEM) was used to track the change in microstructural features with vertical stresses. The results indicated that the k_0 value of expansive soil shows a pronounced nonlinearity and is inextricably linked with vertical stress and moisture content,based on which a prediction formula to estimate the variation in k_0 value with vertical stress during loading stage was proposed; there is a significant exponential increase in k_0 value with overconsolidation ratio(OCR) during unloading stage,and OCR dominates the release of horizontal stress of expansive soil; SEM results revealed that with an increase in vertical stress, the anisotropy of expansive soil microstructure increases dramatically, causing a significant directional readjustment, which is macroscopically manifested as an initially rapid increase in k_0 value; but when vertical stress increases to a critical value, the anisotropy of microstructure increases marginally, indicating a stable orientation occurring in the soil microstructure, which causes the k_0 value to maintain a relatively stable value.
  • Stability analysis of gravity anchor foundation of layered argillaceous sandstone under dry-wet cycles
    ZHENG Jing-cheng, CHEN Wei, ZHENG Ke-ren, GU Yu-peng, WANG Fei, HUANG Zhen, LI Yun
    2023, 20(04): 1118-1130.
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    To investigate the stability of gravity anchors of suspension bridges, in-situ tests of the vertical bearing capacity of the bedrock, shear resistance of the anchor-rock interface, shear resistance of the bedrock were conducted in a suspension bridge project. Under dry-wet cycles, the deterioration law of the mechanical properties of argillaceous sandstone was identified in laboratory tests: the elastic modulus, cohesion and friction of the argillaceous sandstone deteriorated significantly at first few dry-wet cycles and then declined slowly after 10 cycles, ultimately these three mechanical parameters were reduced to about 1/3, 1/3, 2/3 of the initial value respectively. Moreover, numerical simulation was used to restore in-situ shear tests and a good agreement was obtained. Base on the results of in-situ and laboratory tests, the stability of the gravity anchor foundation under natural conditions and drywet cycles was calculated and its failure modes were analyzed. The results demonstrated that the dry-wet cycles caused uneven settlement of the anchor foundation, resulting in more serious stress concentration in the substrate. The dry-wet cycles remarkably reduced the stability coefficient of the anchor foundation, whose failure mode shifted from overturning failure under natural conditions to sliding failure. When there was weak interlayer in the rock layer, the anti-sliding stability of the anchor foundation was affected drastically.
  • Frost heaving force considering synchronous damage to tunnel lining and surrounding rocks under freeze–thaw cycles
    LIU Wen-jun, LING Tong-hua, HE Wen-chao, LIU Xian-jun
    2023, 20(04): 1131-1146.
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    In areas with seasonal freezing, when the tunnel lining concrete is saturated with water infiltrating the interior, the lining and the surrounding rocks will simultaneously freeze.However, the current calculation of the frost heaving force fails to consider the synchronous damage to the lining and surrounding rocks under freeze–thaw cycles. Therefore, as per the elastic calculation model of the frost heaving force and model of steady-state heat transfer of circular tunnels, this study introduces the frost heaving rate of lining and surrounding rocks.First, the analytical solution of frost heaving force is obtained for simultaneous frost heaving of lining and surrounding rocks under any steady-state temperature field. Then, based on the fracture theory and meso-damage mechanics, the damage variables of lining and surrounding rocks under freeze–thaw cycles are extracted, representing their elastic modulus and porosity. Finally, the formula of frost heaving force for synchronous damage to the lining and surrounding rocks at any steady-state temperature field is obtained. The calculation results demonstrate that the lower the temperature inside the lining, the greater the frost heaving force. With the increasing number of freeze–thaw cycles, frost heaving force tends to gradually increase initially,reaching a peak value at 85 freeze–thaw cycles,decreasing to 80% of the peak value at 140 cycles before reaching a constant value. The lining participates in frost heaving, increasing the frost heaving force. The initial increase rate of frost heaving force is 15.7%. Changing the fitting coefficients s1 and s2 of the lining and surrounding rocks can effectively control the magnitude of the frost heaving force in the tunnels.
  • Anisotropic creep behavior of soft-hard interbedded rock masses based on 3D printing and digital imaging correlation technology
    TIAN Yun, WU Fa-quan, TIAN Hong-ming, LI Zhe, SHU Xiao-yun, HE Lin-kai, HUANG Man, CHEN Wei-zhong
    2023, 20(04): 1147-1158.
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    Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering. Compared to other materials, 3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses. In this paper, soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP) sand core technology. Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology. The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels. As the stress level increases, the effect of creep stress on its creep anisotropy increases significantly, and the dip angle is no longer the main factor. The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°, which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°. The tests results are verified by comparing with theoretical and other published studies. The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.
  • Constitutive model for Ya'an mudstone based on mesoscopic breakage mechanism
    HE Yun-yong, CHEN Cong, WANG Fu-ming, GUO Cheng-chao, XIANG Bo, YU Di, LIU En-long, DING Chun
    2023, 20(04): 1159-1169.
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    The slope stability of Ya'an expressway in Sichuan dominated by mudstone strata, is influenced greatly by both the mechanical properties and stressstrain relationship of mudstone. In this paper, the mechanical properties of the Ya'an mudstone samples under triaxial compression conditions were studied,based on an established constitutive model under the framework of breakage mechanics to simulate the mechanical properties of mudstone. Firstly, triaxial compression tests and SEM tests at the confining pressures of 0.5 MPa, 1.0 MPa, and 2.0 MPa were carried out on the mudstone samples, and it was found that the mudstone sample undergoes strain softening and dilatancy followed by the volumetric compaction. Then, based on analysis on the breakage mechanism of the above test results, we idealized the mudstone sample as a binary medium material consisting of the bonded elements and frictional elements, of which the bonded elements are composed of solid matrix and pores, and the frictional elements are composed of broken aggregates. During the loading process, the cementation between clay minerals and non-clay minerals in the mudstone sample is first destroyed, leading to the formation of micro-cracks within the particle aggregate, that is, the bonded elements are gradually damaged during the loading process and gradually turned into the frictional elements, and the two jointly bear the external load. The bonded elements are composed of mudstone matrix and pores, which have the cementitious characteristics of mudstone, and the frictional elements are composed of the broken aggregate with the frictional characteristics of the broken particles. Based on the homogenization theory, the constitutive model for the mudstone is established, and the determining method for model parameters is also given. Finally, the results of the triaxial compression tests of the mudstone samples are predicted by the constitutive model proposed here, which can reflect the main mechanical properties of the mudstone samples.
  • The law of strength damage and deterioration of jointed sandstone after dry-wet cycles
    WANG Gui-lin, ZHANG Tian-yu, ZHANG Liang
    2023, 20(04): 1170-1182.
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    Under the periodic rise and fall of the water level in the Three Gorges Reservoir in China,the rock mass in the ebb and flow zone of the slope is always in a state of a dry-wet cycle. In order to explore the influence of dry-wet cycle on mechanical properties of jointed sandstone, the triaxial and uniaxial compression tests of dry-wet cycle of jointed sandstone were carried out. For the experiment, four groups of samples with different numbers of joints were set up, and the jointed rock samples were subjected to 20 dry-wet cycles. Using both the triaxial compression test and the Mohr-Coulomb(M-C) rock fracture criterion, the strength envelope of the sandstone samples was fitted, and their strength degradation was further analyzed and studied. The results show that:(1) The peak intensity and elastic modulus of the sandstone samples decrease with increased number of dry-wet cycles.(2) The total deterioration of mechanical properties of intact rock samples is bigger than that of jointed sandstone samples as the number of dry-wet cycles increases.(3)With the increase of confining pressure, the peak intensity of intact sandstone samples increases much more than that of jointed sandstone samples, which indicates that joints and their numbers have obvious influence.(4) Joints and their numbers play an important role in guiding the damage effects of sandstone samples, which weaken the damage caused by dry-wet cycles. Therefore, the envelope of the M-C strength criterion of intact sandstone samples moves more than that of jointed sandstone samples.