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Ecological response to the climate change on the northern slope of the Tianshan Mountains in Xinjiang

Science China Earth Sciences 2005年第6期48卷 765-777页

作者： CHEN Xi1, LUO Geping1, XIA Jun2, ZHOU Kefa1, LOU Shaoping3 & YE Minquan4 1. Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China 2. Institute of Geographical and Resources Sciences, Chinese Academy of Sciences, Beijing 100101, China 3. Urumqi Meteorological-satellite Land Station, Urumqi 830011, China 4. Seismological Bureau of Xinjiang Uygur Autonomous Region, Urümqi 830011, China Correspondence should be addressed to Chen Xi Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China Institute of Geographical and Resources Sciences Chinese Academy of Sciences Beijing China Urumqi Meteorological-satellite Land Station Urumqi China Seismological Bureau of Xinjiang Uygur Autonomous Region Urümqi China

The Tianshan Mountains is a high and huge mountain body lying across the central part of Xinjiang, China, and is also the main area where the runoff forms in Xinjiang. In this paper, a set of RS-based study methods is put forward for deriving the information about the natural change of the ecology in arid areas, and the relationship between the climate change trend and the corresponding ecological response on the northern slope of the Tianshan Mountains since recent 40 years is analyzed from the scales of the land cover ecosystems and landscapes based on the observed data of climate, hydrology, modern glaciers and lakes on the northern slopes of the Tianshan Mountains since recent 40 years and the satellite RS data since recent 10 years by using the RS and GIS technologies. The results are as follows: (1) The overall trend of climate change on the northern slope of the Tianshan Mountains since recent 40 years is that both air temperature and precipitation are increased, especially the increase amplitudes of air tempera-ture, precipitation and annual runoff volume are high since the decade of the 1990s; (2) the in-tegrated indexes of the vegetation in all the geographical divisions on the northern slope of the Tianshan Mountains are obviously increased since recent 10 years, especially in the artificial oases and the foothill belts, such a change trend is advantageous for improving the vegetation ecology; and (3) the vegetation ecology in the arid areas is extremely sensitive to the climate change, the vegetation coverage and the biomass on the northern slope of the Tianshan Moun-tains are continuously increased because of the climate change since recent 10 years, their in-crease amplitudes in the plains and during the late stage are obviously higher than that in the mountainous regions and during the early stage.

关键词： north slope of the Tianshan Mountains, climate change, hydrological change, natural change of ecology,RS and GIS, vegetation index.

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Efficient Bayesian networks for slope safety evaluation with large quantity monitoring information

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Geoscience Frontiers 2018年第6期9卷 1679-1687页

作者： Xueyou Li Limin Zhang Shuai Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology

New sensing and wireless technologies generate massive data. This paper proposes an efficient Bayesian network to evaluate the slope safety using large-quantity field monitoring information with underlying physical mechanisms. A Bayesian network for a slope involving correlated material properties and dozens of observational points is constructed.

关键词： slope reliability Monitoring information Bayesian networks Risk management Value of information Big data

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Centrifuge model test and numerical interpretation of seismic responses of a partially submerged deposit slope

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第2期12卷 381-394页

作者： Zhiliang Sun Lingwei Kong Aiguo Guo Mohammad Alam State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Partially submerged deposit slopes are o ften encountered in practical engineering applications.Howeve r,studies on evaluating their stability under seismic loading are still rare.In order to understand the seismic behavior of partially submerged deposit slopes,centrifuge shaking table model tests(50 g) were employed.The responses of horizontal accelerations,accumulated excess pore pressures,deformation mode,and failure mode of the partially submerged deposit slope model were analyzed.In dynamic centrifuge model tests,EQ5 shaking event was applied numerically.The results indicated that in the saturated zone of the deposit slope,liquefaction did not occur,and the measured horizontal accelerations near the water table were amplified as a layer-magnification effect.It was also shown that the liquefaction-resistance of the deposit slope increased under multiple sequential ground motions,and the deformation depth of the deposit slope induced by earthquake increased gradually with increasing dynamic Ioad amplitude.Except for the excessive crest settlement generated by strong shaking,an additional vertical permanent displacement was initiated at the slope crest due to the dissipation of excess pore pressure under seismic loading.The result of particle image velocimetry(PIV) analysis showed that an obvious internal arc-slip was generated around the water table of the partially submerged deposit slope under seismic loading.

关键词： Centrifuge model test Acceleration responses Excess pore pressure Deposit slope

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Couple analysis on strength reduction theory and rheological mechanism for slope stability

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Journal of Central South University 2008年第S1期15卷 351-356页

作者：刘子振言志信段建 School of Machine and Electronics and Architecture Taizhou University School of Civil Engineering and Machanics Lanzhou University

Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheological properties.Then,the concept and the calculation procedure of the safety factor are established at different time.Making use of finite element software ANSYS,the most dangerous sliding surface of the slope can be obtained through the strength reduction technique.According to the dynamic safety factor based on rheological mechanism,a good forecasting could be presented to prevent and cure the landslide.The result shows that the couple analysis reveals the process of the slope failure with the time and the important influence on the long-term stability due to the rheological parameters.

关键词： slope stability strength reduction rheological properties couple analysis safety factor

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Experimental Wave Attenuation Study over Flexible Plants on a Submerged slope

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Journal of Ocean University of China 2017年第6期16卷 1009-1017页

作者： YIN Zegao YANG Xiaoyu XU Yuanzhao DING Meiling LU Haixiang Shandong Province Key Laboratory of Ocean Engineering Ocean University of China Qingdao 266100 P. R. China Engineering College Ocean University of China Qingdao 266100 P. R. China

Using plants is a kind of environmentally-friendly coastal protection to attenuate wave energy. In this paper, a set of experiments were conducted to investigate the wave attenuation performance using flexible grasses on a submerged slope, and the wave attenuation coefficient for these experiments was calculated for different still water depths, slope and grass configurations. It was found that the slope plays a significant role in wave attenuation. The wave attenuation coefficient increases with increasing relative row number and relative density. For a small relative row number, the two configurations from the slope top to its toe and from the slope toe to its top performed equally to a large extent. For a medium relative row number, the configuration from the slope toe to its top performed more poorly than that from the slope top to its toe; however, it performed better than that from the slope top to its toe for a high relative row number. With a single row of grasses close to the slope top from the slope toe, the wave attenuation coefficient shows double peaks. With increasing grass rows or still water depth, the grass location corresponding to the maximum wave attenuation coefficient is close to the slope top. The dimensional analysis and the least square method were used to derive an empirical equation of the wave attenuation coefficient considering the effect of relative density, the slope, the relative row number and the relative location of the middle row, and the equation was validated to experimental data.

关键词： submerged slope flexible grasses wave attenuation coefficient experiment

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Development of a preliminary slope stability calculation method based on internal horizontal displacements

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Journal of Mountain Science 2018年第5期15卷 1129-1136页

作者： PEI Hua-fu ZHANG Si-qi BORANA Lalit YUAN Bing Department of Geotechnical Engineering Dalian University of Technology Dalian 116024 China Department of Civil Engineering Indian Institute of Technology Indore Indore 453552 India. Shenzhen Graduate school Harbin Institute of Technology Shenzhen 518055 China

This paper proposes a horizontal displacement-based approach to determine the potential slip surface of the slope. Firstly, a group of in-situ inclinometers with an appropriate spacing in the horizontal direction is located in the model slope.The equation of horizontal displacement with time for each in-situ inclinometer is fitted during the whole simulation process. Furthermore, the intersection of each inclinometer with potential slip surface is determined by using an optimization model. The slip surface can be obtained by using least square fitting method. Finally, the feasibility and accuracy of the method are validated by a series of numerical simulations. It is noted that the optimization model taking the maximum value of displacement increment gradient as an objective has higher accuracy when compared with other optimization models. This method employed in this study provides a preliminary approach to determine the real-time slope stability based on displacement, which can also be measured by using conventional instruments on site.

关键词： Slip surface slope stability analysis Optimization model Numerical simulation Displacement.

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Effect of hysteresis on the stability of residual soil slope

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International Soil and Water Conservation Research 2019年第3期7卷 226-238页

作者： Christofer Kristo Harianto Rahardjo Alfrendo Satyanaga School of Civil and Environmental Engineering Nanyang Technological UniversityHall of Residence 9Block 46#04-867Singapore639811Singapore

Soil-water characteristic curve (SWCC) is an essential parameter in unsaturated soil mechanics.Matric suction in unsaturated residual soils changes with varying climatic conditions associated with cyclic drying-wetting conditions that result in hysteresis in the SWCC.The soil mechanical behaviour under wetting is crucial since numerous rainfall-induced slope failures occur during the wetting process.However,many slope stability analyses were carried out using drying SWCC.Consequently,the factor of safety (FoS) calculation may not represent the actual field condition.This paper presents the effect of hysteresis in SWCC on the stability of unsaturated residual soil slopes from Bukit Timah Granite in Singapore.The study focused on the analyses considering the differences in pore-water pressure and water content variations under drying and wetting conditions by performing numerical seepage and stability analyses.Each analysis was carried out on a slope subjected to dry and rainy periods under three different conditions:i) using only drying SWCC;ii) using only wetting SWCC;iii) using combined drying and wetting SWCCs.The results indicated that the FoS variations obtained from the numerical analyses incorporating combined SWCC matched more closely those obtained by incorporating only wetting SWCC than those obtained by incorporating only drying SWCC,regardless of the wetting or drying processes that the soil experienced.Moreover,the numerical analyses under high rainfall intensity by incorporating only wetting SWCC gave a more conservative FoS as compared to those obtained by incorporating combined SWCC.Numerical analyses incorporating only drying SWCC gave the most conservative FoS regardless of rainfall intensity.

关键词： SWCC Hysteresis Rainfall Seepage slope stability

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An extension of 2D Janbu's generalized procedure of slices for 3D slope stability analysis Ⅱ--Numerical method and applications

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Science China(Technological Sciences) 2005年第Z1期48卷 184-195页

作者： ZHANG Junfeng LI Zhengguo QI Tao Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

This paper provides a numerical approach on achieving the limit equilibrium method for 3D slope stability analysis proposed in the theoretical part of the previous paper. Some programming techniques are presented to ensure the maneuverability of the method. Three examples are introduced to illustrate the use of this method. The results are given in detail such as the local factor of safety and local potential sliding direction for a slope. As the method is an extension of 2D Janbu’s generalized procedure of slices (GPS), the results obtained by GPS for the longitudinal sections of a slope are also given for comparison with the 3D results. A practical landslide in Yunyang, the Three Gorges, of China, is also analyzed by the present method. Moreover, the proposed method has the advantages and disadvantages of GPS. The problem frequently encountered in calculation process is still about the convergency, especially in analyzing the stability of a cutting corner. Some advice on discretization is given to ensure convergence when the present method is used. However, the problem about convergency still needs to be further explored based on the rigorous theoretical background.

关键词： slope stability analysis, three-dimensional analysis, limit equilibrium.

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Main Detrainment Height of Deep Convection Systems over the Tibetan Plateau and Its Southern slope

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Advances in Atmospheric Sciences 2019年第10期36卷 1078-1088页

作者： Quanliang CHEN Guolu GAO Yang LI Hongke CAI Xin ZHOU Zhenglin WANG School of Atmospheric Sciences Chengdu University of Information Technology and Plateau Atmosphere and Environment Key Laboratory of Sichuan Province

Deep convection systems (DCSs) can rapidly lift water vapor and other pollutants from the lower troposphere to the upper troposphere and lower stratosphere. The main detrainment height determines the level to which the air parcel is lifted. We analyzed the main detrainment height over the Tibetan Plateau and its southern slope based on the CloudSat Cloud Profiling Radar 2B_GEOPROF dataset and the Aura Microwave Limb Sounder Level 2 cloud ice product onboard the Atrain constellation of Earth-observing satellites. It was found that the DCSs over the Tibetan Plateau and its southern slope have a higher main detrainment height (about 10-16 km) than other regions in the same latitude. The mean main detrainment heights are 12.9 and 13.3 km over the Tibetan Plateau and its southern slope, respectively. The cloud ice water path decreases by 16.8% after excluding the influences of DCSs, and the height with the maximum increase in cloud ice water content is located at 178 hPa (about 13 km). The main detrainment height and outflow horizontal range are higher and larger over the central and eastern Tibetan Plateau, the west of the southern slope, and the southeastern edge of the Tibetan Plateau than that over the northwestern Tibetan Plateau. The main detrainment height and outflow horizontal range are lower and broader at nighttime than during daytime.

关键词： main detrainment height deep convection systems Tibetan Plateau and its southern slope A-train

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Statistical characteristics of mesoscale eddies on the continental slope in the northern South China Sea

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Acta Oceanologica Sinica 2020年第3期39卷 36-44页

作者： Zi Cheng Meng Zhou Yisen Zhong Zhaoru Zhang Hailong Liu Lei Zhou School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China

The continental slope in the northern South China Sea(SCS) is rich in mesoscale eddies which play an important role in transport and retention of nutrients and biota. In this study, we investigate the statistical properties of eddy distributions and propagation in a period of 24 years between 1993 and 2016 by using the altimeter data. A total of 147 eddies are found in the continental slope region(CSR), including 70 cyclonic eddies(CEs) and 77 anticyclonic eddies(ACEs). For those eddies that appear in the CSR, the surrounding areas of Dongsha Islands(DS) and southwest of Taiwan(SWT) are considered as the primary sources, where eddies generated contribute more than 60% of the total. According to the spatial distribution of eddy relative vorticity, eddies are weakening as propagating westward. Although both CEs and ACEs roughly propagate along the slope isobaths, there are discrepancies between CEs and ACEs. The ACEs move slightly faster in the zonal direction, while the CEs tend to cross the isobaths with large bottom depth change. The ACEs generally move further into the basin areas after leaving the CSR while CEs remain around the CSR. The eddy propagation on the continental slope is likely to be associated with mean flow at a certain degree because the eddy trajectories have notable seasonal signals that are consistent with the seasonal cycle of geostrophic current. The results indicate that the eddy translation speed is statistically consistent with geostrophic velocity in both magnitude and direction.

关键词： the South China Sea continental slope Dongsha Islands eddy statistics eddy propagation

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