897 resultados para disaster
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岷江上游干旱河谷区水土流失强烈,地质灾害频繁,生态环境十分脆弱,而土壤条件恶劣(水分不足和养分缺乏)是阻碍该区植被恢复的关键因子,因此研究水分和乡土灌木生长对土壤的影响对该区的生态恢复具有指导意义。本文通过定点模拟实验,选取三种优势豆科灌木为研究对象,分别是白刺花(Sophora davidii)、小马鞍羊蹄甲(Bauhinia faberi var. microphylla)和小雀花(Campylotropics polyantha),设置5 个水分梯度,分别为100%、80%、60%、40%和20%田间持水量(FC),对栽种植物与不种植物下土壤理化性质和酶活性进行测定分析,系统比较和研究了不同水分条件和不同乡土灌木生长对干旱河谷区土壤结构、养分循环、酶活性以及微生物量的影响。主要结果如下:1. 无论生长植物与否,土壤的毛管持水量和毛管孔隙度都随着水分含量的减少而降低,最大持水量、总孔隙度和容重变化不大,相应地,土壤中的非毛管孔隙随含水量的减少而升高。各水分条件下,种植植物的毛管持水量和毛管孔隙度低于无植物生长的土壤,非毛管孔隙度相应地高于无植物土壤。土壤含水量在100%-40% FC 时,三种豆科灌木的毛管持水量和毛管孔隙度存在差异,而20% FC 条件下,三种豆科灌木土壤的物理性质基本相同。2. 水分胁迫影响土壤中养分的矿化和积累,主要表现在降低了水溶性碳和铵态氮的含量,中等程度胁迫时(60% FC)促进了有机碳和硝态氮的富集,对速效钾和有效磷没有明显作用。种植豆科灌木后各水分梯度上都增加了有机碳、铵态氮、速效钾和有效磷的积累。增加程度上三种豆科灌木间有一定差异,对于土壤有机碳总量,种植白刺花和小马鞍羊蹄甲明显高于小雀花,同样的情况还出现在铵态氮和速效钾上,但是对于有效磷,种植小雀花后的增加程度则明显高于白刺花和小马鞍羊蹄甲。种植豆科灌木不仅增加了土壤养分的相对含量,也改变了其在水分梯度上的变化趋势及其变化幅度,这种作用主要体现在碳元素和氮元素上。3. 无植物生长时脲酶活性随水分含量的减少而升高,水分胁迫对磷酸酶和过氧化氢酶的作用不显著,蔗糖酶也保持在相对较高的水平。种植植物后,蔗糖酶、磷酸酶活性与无植物时相比有较大幅度的提高,种植白刺花的脲酶活性也升高,其升高的程度在不同水分含量时不同。种植植物还降低了酶活性在水分梯度上的变幅,使之在水分梯度间的差异显著性降低。脲酶活性在指示土壤性质改变方面是较敏感的指标,其它三种酶在不同植物间的差异不明显。4. 在无植物生长时,中等程度的水分胁迫(60% FC)提高了土壤微生物量碳含量,过高或过低的土壤水分均不利于微生物碳的积累。种植小马鞍羊蹄甲后微生物量碳在水分梯度上的变化趋势与无植物生长时一致,而种植白刺花和小雀花后微生物量碳随着水分含量的减少而降低。不同种类植物的微生物量碳在水分梯度上的变化特征也不同,100% FC 条件下三种植物间没有差异,80%和60% FC 条件下小马鞍羊蹄甲显著高于白刺花和小雀花,40%和20% FC 条件下白刺花和小马鞍羊蹄甲也显著高于小雀花,说明不同种类植物随着干旱胁迫程度的加深微生物量碳的降低幅度不同,在极度干旱时,白刺花和小马鞍羊蹄甲土壤依然保持了较高的微生物活性,而小雀花土壤微生物量则明显下降。The dry valley of the upper reaches of the Minjiang River is seriously degradedmountain ecosystem. It was endangered by extremely soil lost and frequentlygeological disaster. Previous studies showed that short of water and nutrients in soilwas the principal limiting factors of vegetation restoration in this area. The typical soiland three dominant leguminous shrubs Sophora davidii, Bauhinia faberi var.microphylla and Campylotropics polyantha in upper reaches of arid Minjiang Rivervalley were considered as experimental material. Two-month old seedlings of eachspecies were exposed to five water supplies (100%, 80%, 60%, 40% and 20% waterfield capacity (FC)) in a temperature and light-controlled greenhouse. Afterthree-month water treatment, soil physiochemical variables and soil microbialactivities were determined by conventional methods. The main results showed that:1. Soil capillary capacity and capillary porosity decreased along water supplyregimes in all treatments, while saturated water capacity, total porosity and bulkdensity kept in a relatively stable level, as a result, the non-capillary porosity andcapacity increased with decrease of water supply. Compared to non-planted soil, theplant-soil systems had a higher non-capillary porosity and capacity, suggestingappropriate oxygen was present in soil to maintain the living of microorganism. Soilof three type shrub species shared the same capillary capacity and capillary porosityunder 20% FC.2. Water soluble carbon and NH4+-N decreased in response to water stress, whiletotal organic carbon and NO3--N promoted by moderate water stress and inhibited by 100% and 20% FC. Total organic carbon, NH4+-N, rapidly available K and availableP increased after the planting of leguminous shrubs in five water supply regimescompared to non-planted soil. For TOC, NH4+-N and rapidly available K, thepromotion effect was higher in S. davidii and B. faberi var. microphylla than C.polyantha planted soil, while available P displayed the opposite side. The planting ofshrubs also reduced the variance of observed traits along water supply gradients.3. Drought stress increased urease activity in non-planted soil, while insignificantdifferences were observed in phosphatase and catalase activity among five watersupply regimes. The planting of leguminous shrubs facilitated the β-glucosidase andphosphatase activity compared to the non-planted soil. It also reduced the variance ofenzyme activity along water supply gradients. Urease was more sensitive to waterstress than other three enzymes.4. Soil water content significantly affected microbial biomass carbon andCmic:Corg. S. davidii and B. faberi var. microphylla showed more drought toleranceability than C. polyantha, attributing not only to their relatively smaller variance ofmicrobial biomass carbon along soil water supply gradients, but also to the highlevel of microbial activity under severe water stress. S. davidii and B. faberi var.microphylla benefited reproduction of soil microorganism at 60%-80% FC, whilesevere drought limited it due to the competition of water and nutrients between plantand soil microorganism.
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1991、 1996、 1997和 1998年的几次洪灾 ,造成了 6171亿元的直接经济损失。除气象因素外 ,水土流失是引发洪灾的一个极为主要的因素。加强领导 ,强化管理 ,加大执法力度 ,加强防洪工程建设 ,坚持综合治理 ,良化生态环境 ,搞好小流域治理是保持水土、治理江河的根本措施
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根据中国西部森林的现状 ,采用生态学与地理学的方法 ,分析了因毁林开荒造成水土流失、洪涝灾害、沙尘风暴、干旱少雨、江河断流、物种减少等危害对国民经济发展所造成的影响 ,以及近几年所产生的一系列生态环境问题 .探讨了退耕还林 (草 )对我国的生态环境治理、西部持续发展、江河整治、国土整治综合措施运用、西部农民脱贫致富的作用 .
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人口、资源、环境和灾害问题已刻不容缓地提到人类发展的日程上来,它不仅是自然科学的问题,同时也是社会问题.在国际环境保护的浪潮日益高涨、国内生态环境保护工作日益发展、社会主义市场经济逐渐发育完善的新形势下,我国正在采取一系列措施,保护生态环境,提高全社会的环保意识,大力开展生态建设,控制环境污染,实现经济建设与环境保护的相互配合和协调发展.笔者在上述背景下,分析了国内外人口增长过快、资源逐减少、环境日趋恶化、灾害发生频繁等严重危害社会发展之恶果,讨论了中国政府自1992年巴西“环发”大会之后所采取的一系列行动.
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我国土壤侵蚀面积之大 ,已严重的影响和制约国民经济的发展和社会的安定。我们从土壤侵蚀与降雨 ,土壤侵蚀与坡长、坡度 ,土壤侵蚀与植被建设三个方面作了系统分析 ,研究土壤侵蚀的最为关键因子 ,并找出其对生态环境的危害性 ,提出最佳的综合防治对策 ,将土壤侵蚀的危害降低到最低程度。
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在人口与经济快速增长的条件下 ,人与自然关系的不协调发展导致了缓发性灾害频繁发生。为了协调环境与资源的关系 ,拓展并优化人类生存空间 ,作者根据多年来收集的缓发性灾害资料与研究成果 ,对缓发性灾害的分类与危害进行了系统分析 ,在采用边缘科学相互交叉的基础上 ,从社会经济可持续发展的战略角度出发 ,总结了国内外防灾工作的经验 ,并得出初步灾害特点 ,为中国的经济建设防灾抗灾提供依据。
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在大量调查、分析与研究的基础上 ,结合中国经济发展中城市快速发展面临的一系列地质灾害 ,采用自然科学与社会科学相互交叉的方法 ,分析了城市地质灾害的危害性及对城市发展的影响 ,根据中国城市发展的实际情况和 2 0 0 1年以后的远景目标 ,因地制宜地提出了整治城市灾害的基本对策与管理措施 ,为国家制定城市发展远景规划和奋斗目标提供基本思路
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分析研究了灾害的危害和非工程措施在国民经济发展中的地位与作用 ,因地制宜的提出了几条防灾对策。
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通过回顾已有的成果 ,分析评价了我国土壤可蚀性研究的进展及存在的问题 ,提出我国土壤可蚀性研究中的标准小区定义。运用野外观测资料 ,研究计算了黄土高原地区土壤可蚀性指标值。结果表明 ,陕北和晋西北一带黄土可蚀性 K值变化于 0 .3~ 0 .7之间 ,并且有以陕西子洲、绥德一带为最大 ,以此为中心 ,向南、向北和向东都减少的变化趋势。
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对日本、美国和中国等国家灾难救援机器人的研究现状和研究计划进行综述。根据世界各国救援机器人技术的研究现状,结合救援机器人在实际应用中取得的经验和教训,归纳和总结出救援机器人的关键性能为:存活能力、运动能力、感知能力、通信能力和作业能力。研究结果表明,灾难救援机器人研究逐步从试验研究转入到实际应用,多种技术融合化、多智能体网络化是今后灾难救援机器人研究的发展方向。防灾、减灾和救灾事关人民生命和财产安全,是国家公共安全的重要组成部分。救援机器人技术是国家发展迫切需要的战略必争的核心技术之一,将在国民经济和安全中起着重要作用并具有重大的战略意义。
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The unique geologic, geomorphic and climatic conditions of southeast Tibet have made the region to develop the multi-style and frequently occurring geologic hazards, especially the collapses and landslides and debris flows along the section of Ranwu-Lulang in Sichuan-Tibet highway. However, most of those geologic hazards have close relationship with the loose accumulations. That is, the loose accumulations are the main carrier of most geologic hazards. Thereof, the huge-thick accumulations along the highway is regarded as the objective in the thesis to study the geologic background, hazarding model and mitigation methods comprehensively, based on the multi-disciplinary theories and former materials. First of all, in the paper, based on field engineering geologic investigations, the genetic type and the characteristics of spatiotemporal distribution of the huge-thick loose accumulations along the highway, have been analysized from the factors of regional geology and geomorphy and climate, as well as the coupling acting of those factors with inoculation and eruption of the loose accumulations geologic hazards. The huge-thick loose accumulations has complex genetic types and specific regulations of spatiotemporal distribution, closely controlled by the outer environment of the region. The accumulations are composed of earth and boulder, with disorder structure and poor sorting, specific forming environments and depositing conditions. And its physical and mechanic properties are greatly distinguished from rock and common earth inland. When Sichuan-Tibet highway was firstly constructed along the north bank of Purlung Tsangpo River, the huge-thick loose accumulations was cut into many high and steep slopes. Through the survey to the cut-slopes and systematic investigation to their failures, the combination of height and angle of the accumulations slope has been obtained. At the same time, the types of genetic structure of those cut-slopes are also analysized and concluded, as well as their failure models. It is studied in the paper that there are piaster, duality, multielement and complexity types in genetic structure, and rip-dump-repose, rip-shear-slip and weathering-flake types in failure models. Moreover, it is briefly introduced present engineering performance methods and techniques dealing with the deformation and failure of the accumulations cut-slope. It is also suggested that several new techniques of slope enforcement and the method of landslide and rockfall avoiding should be applied. The research of high and steep cut-slope along the highway has broadened the acknowledgement of the combination of cut-slope height and angle. Especially, the dissertation also has made the monographic studies about the geologic background and hazarding models and prevention methods of some classic but difficult accumulations geologic hazards. They are: (1) Research of the engineering geologic background of the 102 landslide group and key problems about the project of tunnel. The 102 landslide group is a famous accumulational one composed of glacial tills and glaciofuvial deposit. The tunnel project is a feasible and optional one which can solve the present plight of “sliding after just harnessing” in the 102 section. Based on the glacial geomorphy and its depositing character, distribution of seepage line, a few drillhole materials and some surveying data, the position of contact surface between gneiss and accumulations has been recognized, and the retreating velocities of three different time scales (short, medium and long term) have been approximately calculated, and the weathering thickness of gneiss has also been estimated in the paper. On the basis of above acknowledgement, new engineering geomechnic mode is established. Numerical analysis about the stability of the No.2 landslide is done by way of FLAC program, which supplies the conclusion that the landslide there develops periodically. Thereof, 4 projects of tunnel going through the landslide have been put forwards. Safety distance of the tunnel from clinohefron has been numerically analysized. (2) Research of the geologic setting and disaster model and hazard mitigation of sliding-sand-slope. From the geologic setting of talus cone, it is indicated that the sliding-sand-slope is the process of the re-transportation and re-deposit of sand under the gravity action and from the talus cone. It is the failure of the talus cone essentially. The layering structure of the sliding-sand-slope is discovered. The models of movement and failure of the sliding-sand-slope has been put forwards. The technique, “abamurus+grass-bush fence+degradable culture pan”, is suggested to enforcement and green the sliding-sand-slope. (3) Characteristics and hazarding model and disaster mitigation of debris flow. The sources of solid material of three oversize debris flows have been analysized. It is found that a large amount of moraine existing in the glacial valley and large landslide dam-break are the two important features for oversize debris flow to be taken place. The disaster models of oversize and common debris flows have been generalized respectively. The former model better interpret the event of the Yigong super-large landslide-dam breaking. The features of common debris flow along the highway section, scouring and silting and burying and impacting, are formulated carefully. It is suggested that check dam is a better engineering structure to prevent valley from steeply scouring by debris flow. Moreover, the function of check dam in enforcing the slope is numerically calculated by FLAC program. (4) Songzong ancient ice-dammed lake and its slope stability. The lacustrine profile in Songzong landslide, more than 88 meters thick, is carefully described and measured. The Optical Simulated Luminescence (OSL) ages in the bottom and top of the silty clay layer are 22.5±3.3 kaB.P., 16.1±1.7 kaB.P., respectively. It is indicated by the ages that the lacustrine deposits formed during the Last Glacial Maximum ranging from 25ka B.P. to 15ka B.P. The special characteristics of the lacustrine sediment and the ancient lake line in Songzong basin indicated that the lacustrine sediment is related to the blocking of the Purlung Tsangpo River by the glacier in Last Glacial Maximum from Dongqu valley. The characteristics of the lacustrine profile also indicate that the Songzong ice-dammed lake might run through the Last Glacial Maximum. Two dimensional numerical modeling and analysis are done to simulate the slope stability under the conditions of nature and earthquake by FLAC program. The factor of safety of the lacusrtine slope is 1.04, but it will take place horizontal flow under earthquake activity due to the liquefaction of the 18.33 m silt layer. The realign to prevent the road from landslide is suggested.
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This paper is an important part of the national "863" topic :"Reservoir dynamic model, the development environment and the forecast of remaining oil". In this paper, multi-theory, method and technology are synthesized, and sufficiently use the computer method. We use unifies of qualitative and quota, unifies of macroscopic and microscopic, unifies of dynamic and quiescent description of reservoir, unifies of comprehensive research about reservoir and physical mathematical simulation, unifies of three-dimensional and four-dimensional description of reservoir to research the reservoir of channel sand in Gudao oilfield. and we do some research about the last 10 years of the more than 30 year high pressure water injection and polymer water flooding development, dynamic changes and geologic hazard of reservoir fluid field. It discloses the distribution, genesis and controlling factors. The main innovation achievement and the understanding are: we built-up the framework of the strata and structure, and found genetic type, spatial distribution and aeolotropism of the upper Guantao member. We form the macroscopic and microscopic reservoir model of dynamic evolution, disclose the character, distribution of the macroscopic and microscopic parameter,and the relationship with remaining oil. Next we built-up the model about hydrosialite, and find the styles, group of styles, formation mechanism and controlling factors of the reservoir, disclose the affection of the hydrosialite to remaining oil, pollution of the production environment of oilfield and geologic hazard. The geologic hazards are classified to 8 styles first time, and we disclose the character, distribution law, formation mechanism and controlling factors of the geologic hazard. We built-up the model of the distribution of remaining oil in different periods of Gudao oilfield, and disclose the macroscopic and microscopic formation mechanism of remaining oil in different periods, forecast the distribution of the mobile remaining oil, and find that the main cause of the dynamic evolution of all the sub-models of reservoir fluid field is the geologic process of the reservoir development hydrodynamic force. We develop the reservoir fluid field, research of environment disaster and the description about the support theory, method and technology. The use of this theory in Gudao oilfield has obtained very good economic efficiency, and deepened and develops development geology about the continental facies fault-trough basin, and theory of geologic hazard.
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The topic of Dynamic reservoir model and the distribution of remaining oil after polymer injection of Shengtuo oilfield is a front problem of "the 11th Five-Year Plan" scientific and technological disciplines of Sinopec Corporation. Reservoirs in study area is distributary channel sandstone. After 34 years of water-injection exploitation and 7 years of polymer injection pilot experiments, a highly complex heterogeneous dynamic evolution has been occurred in macro and micro parameters of reservoir model, together with its flow field. Therefore, it’s essential to construct completed reservoir dynamic model for a successfully prediction of the distribution of remaining oil. With a comprehensive application of multidisciplinary theory and technique, using a variety of data and information to maximize the use of computer technology, combining a static and dynamic, macro and micro and 1~4D integration, the research reveals main features, evolution and mechanism, types of geological disasters and their destructivity of reservoir flow field, the macro field, the micro field, the flow field and reservoir development hydrodynamic geological function in different development periods after a long term of polymer injection in Es2 in Shengtuo oilfield. The principle innovation achievements obtained are: 1. Established A, B, C, D four flow units in target formations, revealed the various features and distribution of flow units. 2. Stated environmental pollution and geological disasters induced during oilfield exploitation in study area, and also explained their formation mechanism, controlling factors, destructivity and approaches to disaster reduction. 3. Established dynamic evolution of the macro parameter model, micro-matrix field, pore network field, clay minerals field, seepage dynamic evolution model of six different exploitation stages in study area, also revealed reservoir flow evolution, the law of evolution mechanism after polymer injection. 4. Established macro and micro distribution model of remaining oil after three mining polymer injection during different water cut periods in study area, revealed the formation mechanism and distribution of remaining oil. 5. Established remaining oilforecasting model in study area, and forecasted the formation and distribution of remaining oil in the following six years. 6. It is proposed that reservoir fluid dynamic geological processes are major driving forces for the evolution of different water cut periods, reservoir macro field after the polymer injection and micro seepage field. 7. Established a dynamic reservoir model, proposed matching theory, methods and technology for the description of the remaining oil characterization and prediction, which can deepen the theory and techniques of continental rift basin development geology. Key words: Polymer reservoir; Geological disasters; Dynamic model; Residual oil forecast
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Debris Landslide is one of the types of landslides with the widest distribution, largest quantity, and the closest relationship with engineering construction. It is also one of the most important types of landslides that can cause disaster. This kind of landslide often occurs in the loose slopes which are made up of loose congeries formed by earth filling, residual soil, slope wash, dilapidation, landslide or full weathered material of hard rock. Rainfall is always the chief inducing factor of debris Landslide. Therefore, to research stability of debris Landslide during rainfall not only has important theoretical significance for understanding developing law and deformation and failure mechanism of debris landslide, but also has important practical significance for investigating, appraising, forecasting, preventing and controlling debris landslides. This thesis systematically summarized the relationships between rainfall and landslide, the method to survey water table in the landslides, the deformation and failure mechanism of debris landslide, and the progress in the stability analysis of landslides based on the analyses of data collected widely at home and abroad. The problems in the study of the stability of debris landslide during rainfall was reviewed and discussed. Due to the complicated geological conditions and the random rainfall conditions, the research on the landslides' stability must be based on engineering geological qualitative analysis. Through the collection of the data about the Panxi region and the Three Gorges Reservoir region, the author systematically summarized the engineering geological conditions, hydro-geological condition, distribution characteristics of stress field in the slope, physical and mechanical properties and hydro-mechanical properties of debris. In the viewpoint of dynamics of soil water and hydromechanics, physical process of rainfall to supply groundwater of debris landslides can be divided into two phases, i.e. non-saturated steady infiltrating phase and saturated unsteady supplying phase. The former can be described by mathematical model of surface water infiltration while the latter can be described by equivalent continuous medium model of groundwater seepage. With regard to specific hydrological geology system, we can obtain the dynamic variation law of water content, water table, landslide stability of rock and soil mass, along with quantity and duration of rainfall after the boundary condition on hydrological geology has been ascertained. This is a new way to study the response law of groundwater in the landslides during rainfall. After wet face of rock and soil mass connects with ground water table, the raising of water table will occur due to the supply of rainfall. Then interaction between ground water and rock and soil mass will occur, such as the action of physics, water, chemistry and mechanics, which caused the decrease of shearing strength of sliding zone. According to the action of groundwater on rock and soil mass, a concise mechanical model of debris landslide’s deformation was established during rainfall. The static equilibrium condition of landslide mass system was achieved according to the concise mechanical model, and then the typical deformation and failure process and failure mode of debris landslide during rainfall were discussed. In this thesis, the former limiting equilibrium slice method was modified and improved based on shearing strength theory of , a stability analysis program of debris landslide was established and developed taking account of the saturated-unsaturated seepage, by introducing the shearing strength theory of unsaturated soil mass made by (1978). The program has reasonable data storage and simple interface and is easy to operate, and can be perfectly used to carry out sensitivity analysis of influencing factors of landslides' stability, integrated with the program of Office Excel. The design of drainage engineering are always bases on empirical methods and is short of effective quantitative analysis and appraise, therefore, the conception of critical water table of debris landslide was put forward. For debris landslides with different kinds of slide face in the engineering practice, a program to search the critical water table of debris landslide was developed based on native groundwater table. And groundwater table in the slope should be declined below the critical water table in the drainage works, so the program can be directly used to guide drainage works in the debris landslide. Taking the slope deformation body in the back of former factory building of Muli Shawan hydroelectric power station as an example, a systematic and detailed research on debris landslides' stability during rainfall was researched systematically, the relationship among quantity of rainfall, water table and stability of slope was established, the debris landslides' stability in process of rainfall from dynamic viewpoint was analyzed and researched.
Resumo:
The velocity field is important to investigate the motion and strain parameters of the block. It is also important to investigate the deformation of the fault, for example, the accumulation of strain and stress, at the boundary of the block. The dislocation model is a classic method to simulate the velocity field. In dislocation model, the aseismic crustal deformation is regarded as the sum of the rigid block motion and the effect of the locked fault. We modify the dislocation model in two aspects. Firstly, the block motion is assumed to be the sum of rotation and linear strain rather than the rigid motion. Secondly, the elastic layered-earth model rather than the homogenous half-space model is applied to calculate the effect of the locked part. The 1990~1995 annually Global Position System (GPS) velocity data of the Taiwan area are used in our dislocation model. The misfit of our modified model is smaller than that of the origin model clearly. Our simulation shows, in eastern Coastal Range, the velocity decreases northward rapidly from Chimei Fault, which may result from the high crustal compressive rate of about 30 mm•a-1 at Chimei Fault. The lock of fault in southern part is stronger than that in northern part generally. In western Taiwan, the most strongly locked faults appear in the southern Coastal Plain where many disaster earthquakes occur frequently. The calculated strain and rotation rates consist with previous results in most areas. The strain rate field reveals the nearly NW-SE compression in most parts of Taiwan with a fan-shaped distribution. The rotation rate field reveals anticlockwise rotation in eastern and southern Taiwan while clockwise rotation in western and northern Taiwan, generally.