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On Post-Shear-Instability in Saturated soils

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地学前缘 2009年第S1期16卷 262-263页

作者： Xiaobin Lu~1,Xuhui Zhang~2 1.institute of mechanics,chinese academy of sciences,Beijing 100080,china. 2.institute of Mountain Hazard and Environment,chinese academy of sciences,Chengdu china,

The study on the development of shear band is very import since it is the main reason of landslide. According to experimental results,there is only one shear band forming at last when the soil specimen beard shear loa... 详细信息

关键词： shear band landslide finite amplitude disturbances

Nutrient Cycling and Balance in Red soil Agroecosystem and Their Management

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Pedosphere 2000年第2期10卷 107-116页

作者： HE YUANQIU and LI ZHIMING.(institute of soil Science, the chinese academy of sciences, P.O. Box 821, Nanjing 210008 china) 中科院南京土壤所江苏南京 210008

An experiment was conducted in a red soil derived from Quaternary red clay in the Ecological ExperimentStation of Red soil, the chinese academy of sciences, located in Yingtan (28° 15′ 30″ N, 116° 55′ 30″E), Jiangxi Province. The results show that the major ways of nutrient loss are leaching and nitrogenvolatilization. Rationalizing crop distribution, stimulating nutrient recycling, and improving internal nutrientflow are effective measures to decrease nutrient loss and to promote nutrient utilization efficiency. Theimportant ways of regulating nutrient cycling and balance in the agroecosystem of the red soil are to establishoptimal eco-agricultural models, practice balanced fertilization and combine the cropping system with thelivestock system.

关键词： balance nutrient cycling red soil agroecosystem regulation options

Compound contamination and secondary ecological effects of Cd and As in soil－alfalfa ecosystems

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Journal of Environmental sciences 1994年第3期6卷 330-336页

作者： Zhou Qixing Gao Zhengmin(institute of Applied Ecology, chinese academy of sciences),Shenyang 10015,china)

d and As both have harmful effects on the growth,development and seed germination of alfalfa, especially in such a condition as the coexistence of Cd and As in soil environment The research using the pot-culture imitative method first found that if soil was simultaneously polluted by Cd and As,function of alfalfa absorbing Cd from soil may be promoted because of the existence of As,in conversely,Cd may inhibit alfalfa plant from absorbing As It was also found that secon- dary ecological effects were most likely to be brought out due to the coexistence of Cd and As. For example,alfalfa is passive to excessively absorb Cu and Pb .The harmful effects undoubtedly intensi- fy the contamination of alfalfa, The results showed that the mechanism of the interaction among Cd,As,Pb and Cu in soil-alfalfa ecosystems is very complicated.

关键词： compound contamination,ecological effects,Cd As soil.

Effect of rock mass structure and block size on the slope stability——Physical modeling and discrete element simulation

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Science china(Technological sciences) 2005年第z1期48卷 1-17页

作者： LI Shihai1, LIAN Zhenzhong1,2 & J. G. Wang3 1. institute of mechanics, chinese academy of sciences, Beijing 100080, china 2. Graduate School, chinese academy of sciences, Beijing 100060, china 3. Tropical Marine Science institute, National University of Singapore, Singapore 119260 chinese Acad Sci Inst Mech Beijing 100080 Peoples R China chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ Singapore Trop Marine Sci Inst Singapore 119260 Singapore

This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

关键词： rock masses, slope stability, DEM simulation, block size effect, joints configuration effect, limit equilibrium method.

VARIATION OF SEDIMENT YIELD AS RIVER BASIN AREAIN THE MIDDLE YELLOW RIVER BASIN

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International Journal of Sediment Research 1999年第2期14卷 333-337页

作者： LU Jinfa (institute of Geography, chinese academy of sciences, Beijing, 100101,china)

Both decrease and increase of sediment yield were observed in main tributaries basins of the Middle Yellow River as basin area increases. Bio-climatic and morphologic features exert most important control on the relationship between specific sediment yield and drainage basin area. Sediment yield data from various environments show different trends of variation in sediment yield for loess. rock and rock/loess mixed regions.

关键词： Sediment yield Basin area Yellow River

Leaching and Redistribution of Nutrients in Surface Layer of Red soils in Southeast china

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Pedosphere 2000年第2期10卷 135-142页

作者： SUN BO ZHANG TAOLIN and ZHAO QIGUO(institute of soil Science, the chinese academy of sciences, P.O. Box 821, Naniing 210008 china) 中科院南京土壤所江苏南京 210008

The leaching and redistribution of nutrients in the surface layer of 4 types of red soils in Southeastchina were studied with a lysimeter experiment under field conditions. Results showed that the leachingconcentrated in the rainy season (from April to June). Generaily, the leaching of soil nutrients from thesurface layer of red soils was in the order of Ca > Mg > K > NO3-N. In fertilization treatment, the totalamount of soil nutrients leached out of the surface layer in a red soil derived from granite was the highest inall soils. The uptake by grass decreased the leaching of fertilizer ions in surface layer, particularly for *** total N and exchangeable K, Ca and Mg in the surface layer decreased with leaching and grass uptakeduring the 2 years without new fertilization of urea, Ca(H2PO4)2, KCl, CaCO3 and MgCO3. Ca movedfrom the application layer (0~5 cm) of fertilizer and accumulated in the 10~30 cm depth in the soils studiedexcept that derived from Quaternary red clay. The deficiency of soil exchangeable K will become a seriousdegradation process facing the Southeast china.

关键词： leaching nutrients red soils redistribution Southeast china

Interaction of NPK Fertilizers During Their Transformation in soils: I. Dynamic Changes of soil pH

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Pedosphere 2003年第3期13卷 257-262页

作者： WANG HUOYAN, ZHOU JIANMIN, CHEN XIAOQIN, LI SHOUTIAN, DU CHANGWEN and DONG CAIXIAinstitute of soil Science, the chinese academy of sciences, Nanjing 210008 (china) institute of soil Science the Chinese Academy of Sciences Nanjing 210008

Dynamic changes of soil pH as influenced by ammonium sulfate (AS),monocalciuin phosphate (MCP), potassium chloride (KCl) and their interaction in soils were evaluatedin incubation experiments. Applying these fertilizers significantly reduced soil pH values in allcases and followed sequences of AS > MCP > KCl, MCP > KCl > AS and KCl > AS > MCP for the paddy,calcareous and red soils, respectively. The AS-induced reduction of pH in the three soils followedthe sequence of red soil > paddy soil > calcareous soil, while in MCP and KCl systems the reductionof pH followed the sequences of calcareous soil > paddy soil > red soil and red soil > calcareoussoil > paddy soil, respectively. The interactions of the NPK fertilizers on pH were significant. MCPplus KCl or MCP plus AS reduced pH values more than the fertilizers applied solely in the paddysoil, but AS partly counteracted the effect of MCP on pH in the 1 d sample of the calcareous *** effect of MCP on pH was trivial when MCP was applied in combination with KCl or AS in the redsoil. When applied in combination with AS, KCl did not affect soil pH initially, but suppressed thereduction of pH at the later incubation stage, which was related to inhibition of nitrification byKCl in the soils.

关键词： nitrogen pH phosphorus potassium

THE PRESSURE TRANSIENT ANALYSIS OF DEFORMATION OF FRACTAL MEDIUM

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Journal of Hydrodynamics 2008年第3期20卷 306-313页

作者： ZHANG Yi-gen TONG Deng-ke institute of mechanics Chinese Academy of Sciences Beijing 100080 China Research institute of Geological sciences Shengli Oilfield Company Sinopec Dongying 257015 China School of Mathematics and Computational sciences China University of Petroleum （East China） Dongying257061 China

The assumption of constant rock properties in pressure-transient analysis of stress-sensitive reservoirs can cause significant errors in the estimation of temporal and spatial variation of pressure. In this article, the pressure transient response of the fractal medium in stress-sensitive reservoirs was studied by using the self-similarity solution method and the regular perturbation method. The dependence of permeability on pore pressure makes the flow equation strongly nonlinear. The nonlinearities associated with the governing equation become weaker by using the logarithm transformation. The perturbation solutions for a constant pressure production and a constant rate production of a linear-source well were obtained by using the self-similarity solution method and the regular perturbation method in an infinitely large system, and inquire into the changing rule of pressure when the fractal and deformation parameters change. The plots of typical pressure curves were given in a few cases, and the results can be applied to well test analysis.

关键词： stress-sensitive reservoir fractal permeability modulus pressure analysis

Degradation of soil Nutrients in Southeast china

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Pedosphere 2000年第2期10卷 165-170页

作者： LU RUKUN SHI ZHENGYUAN and SUN Bo(institute of soil Science, the chinese academy of sciences, P.o. Box 821, Naviing 210008 china) 中科院南京土壤所江苏南京 210008

A total of 2 190 soil nutrient data in the Second National soil Survey of china were collected to assess thedegradation of soil nutrients in the hilly region of Southeast china. The definition of soil nutrient degradationis suggested firstly then the evaluation criteria are set up and the current status of degradation of red soil and latosol is assessed. The percentages of areas in four grades of soil nutrient degradation, i.e., slightlydeficient, medium deficient, severely deficient and extremely deficient, were 21.3%, 43.3%, 16.2% and 3.0%for soil total N; 0.7%, 6.4%, 16.7% and 76.2% for soil available P; and 25.4%, 26.3%, 8.6% and 5.0% forsoil available K, respectively. The severity of soil nutrient degradation was in the order of P > N > K. Themajor factors leading to the degradation of soil nutrients in quantity include soil erosion, leaching and theconsumption by crops. And the principal faCtor affecting the degradation of soil nutrieots in availability isthe fixation of N, P and K, especially the fixation of phosphorus. The average amouat of P fixed by soils is408 mg kg-1, and upland soils can fix more P than paddy soils.

关键词： nutrient degradation red soil soil degradation