Determination of shear strength of conglomerates using a caterpillar D9 ripper and comparison with alternative methods   总被引：1，自引：0，他引：1  

J. P. Savely 《Geotechnical and Geological Engineering》1990,8(3):203-225

Summary A method of determining shear strength in Gila Conglomerates at Inspiration Mine (now Cyprus Miami Mine), Arizona, using Caterpillar D9H and D9L rippers is described. The results are compared with data obtained using laboratory direct shear tests — both large and small scale, back analysis and boulder modelling. The significance of scale, particularly relating to boulder size is discussed.  相似文献   

Performance of surface footing on geocell-reinforced soft clay beds   总被引：2，自引：0，他引：2  

Sitharam G. Thallak  Sireesh Saride  Sujit Kumar Dash 《Geotechnical and Geological Engineering》2007,25(5):509-524

This paper presents the results of laboratory model tests carried out to develop an understanding of the behaviour of geocell-reinforced soft clay foundations under circular loading. Natural silty clay was used in this study. The geocells were prepared using biaxial polymer grid. The performance of the reinforced bed is quantified using non-dimensional factors i.e., Bearing capacity improvement factor (I_f) and Percentage reduction in footing settlement (PRS). The test results demonstrate that the geocell mattress redistributes the footing load over a wider area thereby improving the performance of the footing. The load carrying capacity of the clay bed is increased by a factor of up to about 4.5 times that of unreinforced bed. From the pressure-settlement responses, it is observed that the geocell-reinforced foundation bed behaves as a much stiffer system compared to the unreinforced case indicating that a substantial reduction in footing settlement can be achieved by providing geocell reinforcement in the soft clay bed. The maximum reduction in footing settlement obtained with the provision of geocell mattress of optimum size placed close to the footing is around 90%. Further improvement in performance is obtained with provision of an additional planar geogrid layer at the base of the geocell mattress.  相似文献   

城市地下排水网雨水入流预测模型研究     

程先云  刘洪禄  郑凡东 《水文》2007,27(6):42-45

引入水箱模型进行城市地下排水设施降雨一侵入水的模拟，探讨了初期蓄流值对模拟结果的影响并提出了相应的解决办法；由于模型参数多、非线性，参数的率定采用通用优化分析计算平台PowerFit，并获得了满意的结果，表明：①水箱模型适用于地下排水设施雨洪模拟和预测，可为市政规划设计和城市灾害预报提供可靠依据；②PowerFit全局优化能力强、简单易用，可广泛应用于水利水电等工程领域中的优化计算。  相似文献   

Epikarst communities: biodiversity hotspots and potential water tracers   总被引：1，自引：0，他引：1  

Tanja Pipan  David C. Culver 《Environmental Geology》2007,53(2):265-269

There is an exceptionally rich aquatic fauna in the epikarst, the skin of karst. High species richness in the epikarst, coupled with its special vulnerability as the first point of entry of nearly all toxic spills, makes its protection especially important. The epikarst fauna may also be an useful tool in tracing the potential route of pollutants. Copepods in epikarst have extremely local distributions, and their body size is such that they are largely at the mercy of directional flows. In a series of caves in southwest Slovenia and West Virginia, a significant fraction of the copepod species occur in less than 100 m of linear extent. This suggests a pattern of highly restricted lateral flow under normal conditions and the distribution of copepods could potentially be used to trace water movement. Under high flow conditions as would often be the case with toxic spill, mounding of water may increase the lateral radius of flow. Nevertheless, copepods may be useful tracers.  相似文献   

Transport and deposition of suspended particles in saturated porous media: hydrodynamic effect   总被引：1，自引：1，他引：1  

Nasre-Dine Ahfir  Hua Qing Wang  Ahmed Benamar  Adbellah Alem  Nicolas Massei  Jean-Paul Dupont 《Hydrogeology Journal》2007,15(4):659-668

A laboratory study was undertaken to determine the transport and deposition rate of suspended particles in columns of saturated porous media (gravel and glass beads), where the porous media were subjected to steady-state flow. Silt particles with a mode of 14 μm diameter (used as the suspended particles) and fluorescein (as the conservative tracer) were injected into the columns in short pulses. The breakthrough curves were competently described with the analytical solution of a convection–dispersion equation with a first-order deposition rate. The experiments were performed using different flow rates. The suspended particle size distribution, the porous media, and the flow rates themselves were the main factors retained in this study to investigate the mechanisms governing the transport and deposition kinetics in detail. The results showed the existence of a flow rate, beyond which suspended particles travel faster than the conservative tracer. A decrease of the deposition rate of suspended particles beyond a critical flow velocity was also observed. Such behaviour led to consideration of the couple hydrodynamic-gravity forces at high flow rates. As the hydrodynamic force increases, particle deposition rates are reduced due to the effect of hydrodynamic forces inhibiting the deposition.  相似文献   

Equivalent force control method for generalized real‐time substructure testing with implicit integration     

Bin Wu  Qianying Wang  P. Benson Shing  Jinping Ou 《地震工程与结构动力学》2007,36(9):1127-1149

This paper presents a new method, called the equivalent force control method, for solving the nonlinear equations of motion in a real‐time substructure test using an implicit time integration algorithm. The method replaces the numerical iteration in implicit integration with a force‐feedback control loop, while displacement control is retained to control the motion of an actuator. The method is formulated in such a way that it represents a unified approach that also encompasses the effective force test method. The accuracy and effectiveness of the method have been demonstrated with numerical simulations of real‐time substructure tests with physical substructures represented by spring and damper elements, respectively. The method has also been validated with actual tests in which a Magnetorheological damper was used as the physical substructure. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

液压阻尼系统（HDS）控制立式钢制储罐地震响应分析     

袁朝庆  李惠等 《地震工程与工程振动》2001,21(4):163-167

本文采用液压阻尼系统（HDS）控制立式圆柱钢制储罐的地震反应，建立了安装HDS储罐的力学分析模型，并进行了数值计算，从频域对安装HDS后储罐的地震响应进行了分析，研究了HDS的减震效果和HDS和HDS参数对储罐地震反应的影响。  相似文献   

油罐地基不均匀沉降原因分析及纠偏加固处理方法     

张栋材 《水文地质工程地质》2001,28(5):69-72

某油罐因地基发生不均匀沉降而倾斜，本文通过对油罐发生均匀沉降的原因分析，提出了倾斜油罐纠偏设计及地基处理方案，叙述了地基处理及纠偏施工方法，施工处理后经过半年的使用观察，效果良好。  相似文献   

Use of deuterated water as a conservative artificial groundwater tracer     

Matthew W. Becker  Tyler B. Coplen 《Hydrogeology Journal》2001,9(5):512-516

Conservative tracers are necessary to obtain groundwater transport velocities at the field scale. Deuterated water is an effective tracer for this purpose due to its similarity to water, chemical stability, non-reactivity, ease of handling and sampling, relatively neutral buoyancy, and reasonable price. Reliable detection limits of 0.1 mg deuterium/L may be obtained in field tests. A field example is presented in which deuterated water, bromide, and pentafluorobenzoic acid are used as groundwater tracers. Deuterated water appeared to be transported conservatively, producing almost identical breakthrough curves as that of other soluble tracers. Electronic Publication  相似文献   

Groundwater resources evaluation case study via discrete fracture flow modeling   总被引：1，自引：0，他引：1  

M. Wang  P. H. S. W. Kulatilake  B. B. Panda  M. L. Rucker 《Engineering Geology》2001,62(4):267-291

The Arizona Department of Transportation (ADOT) is preparing to upgrade State Route 260 between Payson and Heber. It is estimated that a total of about one million cubic meters of water will be required for embankment construction during a period of about 84 months to upgrade the first 33.8 km of the highway. ADOT is investigating various sources of construction water for use in the highway improvement project, including groundwater resources along the highway corridor. A region known as the RV site, underlain by fractured granite, is located 12.9 km east of Payson. The site includes three springs, a creek and several wells. Several boreholes and observation wells were made to a maximum depth of 157 m to obtain fracture data and to conduct pumping tests with monitoring. Fracture data recorded by acoustic televiewer logs were used to build a fracture network model for the rock mass. Results of a 24-hour and a 7-day pumping tests were used to calibrate hydraulic parameters of a finite element discrete fracture fluid flow model considering the region as a heterogeneous, anisotropic, fractured medium. A 38-day multi-well pumping test was used to validate the calibrated numerical model. The calibrated model showed the capability to provide reasonably accurate predictions for new pumping tests conducted in the same well field. The validated model was then used to simulate pumping exceeding a 7 year period under different scenarios incorporating different sets of boundary conditions and different pumping rates at multi-wells, with and without recharge, to evaluate the yield of the aquifer and to assess the effect of long-term pumping on the environment. The results indicated that (a) the combined yield of the wells in the RV site is sufficient to meet the water demand for the ADOT highway project and (b) the water levels in the well field would decline between 3.0 and 7.6 m after one year of pumping and by 12.2 to over 30.5 m during the life of the project.  相似文献