Modeling of layered infinite slope failure triggered by rainfall   总被引：3，自引：2，他引：1  

Tung-Lin Tsai  Sen-Jung Chiang 《Environmental Earth Sciences》2013,68(5):1429-1434

The infinite slope is typically regarded as composed of a single-layered soil with a uniform property in various physical-based models used for modeling rainfall-induced shallow landslides. This study extends the physical-based model to consider the layered infinite slope to examine the importance of soil layer distribution for rainfall-induced shallow landslides. Hypothetical scenarios of infinite slope composed of soil layers with different thicknesses and parameters are employed to conduct this examination. The results show that pressure heads caused by rainfall infiltration are strongly related to soil layer distribution. This shows the significant influence of soil layer distribution in assessing infinite slope stability. Failure of a layered infinite slope does not necessarily occur at the impervious bottom of the hillslope soil, but may also occur at the interface between two soil layers. This result shows that a neglect of soil layer distribution could misestimate failure depth. Hence, soil layer distribution must be considered to reliably analyze infinite slope failure induced by rainfall.  相似文献   

A recurrent support vector regression model in rainfall forecasting     

Ping‐Feng Pai  Wei‐Chiang Hong 《水文研究》2007,21(6):819-827

To minimize potential loss of life and property caused by rainfall during typhoon seasons, precise rainfall forecasts have been one of the key subjects in hydrological research. However, rainfall forecast is made difficult by some very complicated and unforeseen physical factors associated with rainfall. Recently, support vector regression (SVR) models and recurrent SVR (RSVR) models have been successfully employed to solve time‐series problems in some fields. Nevertheless, the use of RSVR models in rainfall forecasting has not been investigated widely. This study attempts to improve the forecasting accuracy of rainfall by taking advantage of the unique strength of the SVR model, genetic algorithms, and the recurrent network architecture. The performance of genetic algorithms with different mutation rates and crossover rates in SVR parameter selection is examined. Simulation results identify the RSVR with genetic algorithms model as being an effective means of forecasting rainfall amount. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Long‐term runoff forecasting by combining hydrological models and meteorological records     

Tao‐Chang Yang  Pao‐Shan Yu  Chiang‐Chi Chen 《水文研究》2005,19(10):1967-1981

Reservoir operation is generally based on the inflows of the upstream catchment of the reservoir. If the arriving inflows can be forecasted, that can benefit reservoir operation and management. This study attempts to construct a long‐term inflow‐forecasting model by combining a continuous rainfall–runoff model with the long‐term weather outlook from the Central Weather Bureau of Taiwan. The analytical results demonstrate that the continuous rainfall–runoff model has good inflow simulation performance by using 10‐day meteorological and inflow records over a 33‐year period for model calibration and verification. The long‐term inflow forecasting during the dry season was further conducted by combining the continuous rainfall–runoff model and the long‐term weather outlook, which was found to have good performance. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Investigating the impact of the Chi‐Chi earthquake on the occurrence of debris flows using artificial neural networks     

Fi‐John Chang  Yen‐Ming Chiang  Wong‐Shuo Lee 《水文研究》2009,23(19):2728-2736

Debris flows have caused enormous losses of property and human life in Taiwan during the last two decades. An efficient and reliable method for predicting the occurrence of debris flows is required. The major goal of this study is to explore the impact of the Chi‐Chi earthquake on the occurrence of debris flows by applying the artificial neural network (ANN) that takes both hydrological and geomorphologic influences into account. The Chen‐Yu‐Lan River watershed, which is located in central Taiwan, is chosen for evaluating the critical rainfall triggering debris flows. A total of 1151 data sets were collected for calibrating model parameters with two training strategies. Significant differences before and after the earthquake have been found: (1) The size of landslide area is proportioned to the occurrence of debris flows; (2) the amount of critical rainfall required for triggering debris flows has reduced significantly, about half of the original critical rainfall in the study case; and (3) the frequency of the occurrence of debris flows is largely increased. The overall accuracy of model prediction in testing phase has reached 96·5%; moreover, the accuracy of occurrence prediction is largely increased from 24 to 80% as the network trained with data from before the Chi‐Chi earthquake sets and with data from the lumped before and after the earthquake sets. The results demonstrated that the ANN is capable of learning the complex mechanism of debris flows and producing satisfactory predictions. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Two-dimensional stresses in a saturated poro-elastic foundation beneath a rigid structure—part. I. An impervious dam in a river     

Chiang C. Mei  Arthur E. Mynett 《国际地质力学数值与分析法杂志》1983,7(1):57-74

The problem of an impervious dam on a poro-elastic foundation is solved analytically. Using the known solution for the fluid pressure in the pores, the elastostatic stress field in the solid skeleton is analysed by reduction to two simpler problems whose solutions can be obtained by complex variable techniques. For welded contact, the rotation of the dam base is then found along with the stresses and strains in the ground. Modification for finite friction along the base is outlined in the appendix.  相似文献   

Aerobic Biodegradation of Benzene, Toluene, and Xylene in a Sandy Aquifer—Data Analysis and Computer Modeling     

C. Y. Chiang  J. P. Salanitro  E. Y. Chai  J. D. Colthart  C. L. Klein 《Ground water》1989,27(6):823-834

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Defining an estuary using the Hilbert-Huang transform     

Yen-Chang Chen  Hsiao-Wen Chiang 《水文科学杂志》2013,58(4):841-853

Abstract

Researchers have used various physical, chemical, or topographic features to define estuaries, based on the needs of their particular subject. The principal features of estuaries are the tides that influence their water stages; thus, the boundaries of an estuary can be determined based on whether the water stage is subject to tidal influence. However, the water stage is also influenced by the upstream river discharge. A hydrograph of water stage will therefore include both non-stationary and nonlinear features. Here, we use the Hilbert-Huang Transform (HHT), which allows us to process such non-stationary and nonlinear signals, to decompose the water-stage hydrographs recorded at different gauging stations in an estuary into their intrinsic mode function (IMF) components and residuals. We then analyse the relationships between the frequencies of IMFs and known tidal components. A frequency correlation indicates that the water stage of the station is subject to tidal influences and is located within the estuary. The spatial distribution of the stations that are subject to tidal influences can then be used to define the estuary boundaries. We used data from gauging stations in the estuary region of Taiwan's Tanshui River to assess the feasibility of using the HHT to define an estuary. The results show that the HHT is a dependable and easy method for determining the boundaries of an estuary.

Citation Chen, Y.-C., Kao, S.-P., and Chiang, H.-W., 2013. Defining an estuary using the Hilbert-Huang transform. Hydrological Sciences Journal, 58 (4), 841–853.  相似文献   

Component and shaking table tests for full‐scale multiple friction pendulum system     

C. S. Tsai  Wen‐Shin Chen  Tsu‐Cheng Chiang  Bo‐Jen Chen 《地震工程与结构动力学》2006,35(13):1653-1675

The use of base isolation in developed countries including the U.S. and Japan has already been recognized as a very effective method for upgrading the seismic resistance of structures. In this study, an advanced base‐isolation system called the multiple friction pendulum system (MFPS) is investigated to understand its performance on seismic mitigation through full‐scale component and shaking table tests. The component tests of the advanced Teflon composite coated on the sliding surface show that the friction coefficient of the lubricant material is a function of the sliding velocity in the range of 0.03–0.12. The experimental results also indicate that there were no signs of degradation of the sliding interface observed after 2000 cycles of sliding displacements. A full‐scale MFPS isolator under a vertically compressive load of 8830 KN (900 tf) and horizontally cyclic displacements was tested in order to assess the feasibility of the MFPS isolator for its practical use. After 248 cycles of horizontal displacement reversals, the behaviour of the base isolator was almost identical to its behaviour during the first few cycles. The experimental results of the shaking table tests of a full‐scale steel structure isolated with MFPS isolators show that the MFPS device can isolate seismic transmitted energy effectively under soft‐soil‐deposit site earthquakes with long predominant periods as well as strong ground motions with short predominant periods. These test results demonstrate that the MFPS isolator possesses excellent durability and outstanding earthquake‐proof capability. Furthermore, the numerical results show that the mathematical model proposed in this study can well predict the seismic responses of a structure isolated with MFPS isolators. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Impairment of sea urchin sperm quality by UV-B radiation: predicting fertilization success from sperm motility   总被引：4，自引：0，他引：4  

Au DW  Chiang MW  Tang JY  Yuen BB  Wang YL  Wu RS 《Marine pollution bulletin》2002,44(7):583-589

Sperm quality of the sea urchin, Anthocidaris crassispina, after exposure to environmentally realistic UV-B irradiances, was assessed by changes in sperm motility (measured by the computer-assisted sperm analysis (CASA) system), and related to subsequent fertilization success. Percentage motile sperm of A. crassispina declined significantly after exposure to a UV-B dose of 16.2 kJ m(-2), while sperm motion velocity as measured by curvilinear velocity (VCL), straight line velocity (VSL), and average path velocity (VAP) showed significant reduction after exposure to a UV-B dose of 5.4 kJ m(-2). A parallel study showed that fertilization success was significantly reduced after sperm were exposed to UV-B doses > or = 5.4 kJ m(-2). Notably, the four sperm motility parameters were strongly correlated with fertilization success (P < 0.001), followed the increasing order: VSL (r = 0.8) < % motile sperm (r = 0.804) < VCL (r = 0.912) < VAP (r = 0.928). Fertilization success is best predicted by VAP using the exponential model: y = 8.678 + 90.202/[1 + exp(82.83 - x)/10.27)] (r(2) = 0.95). Thus, impairment of sperm motility of sea urchin, as measured by the CASA method, can be used to predict reproductive success and ecological effects.  相似文献   

Modeling typhoon- and earthquake-induced landslides in a mountainous watershed using logistic regression   总被引：4，自引：2，他引：4  

Kang-Tsung Chang  Shou-Hao Chiang  Mei-Ling Hsu 《Geomorphology》2007,89(3-4):335-347

Landslides can be caused by storms and earthquakes. Most logistic regression models proposed in recent years have been targeted at rainfall-induced landslides. In areas such as Taiwan, where landslides can be triggered by typhoons (tropical cyclones) and earthquakes, a rainfall-induced model is insufficient because it provides only a partial explanation of landslide occurrence and overlooks the potential effect of earthquakes on typhoon-triggered landslides. This study used landslides triggered by a major earthquake and a typhoon prior to the earthquake to develop an earthquake-induced model and a typhoon-induced model. The models were then validated by using landslides triggered by three typhoons after the earthquake. According to the results, typhoon-triggered landslides tended to be near stream channels and earthquake-triggered landslides were more likely to be near ridge lines. Moreover, a major earthquake could still affect the locations of typhoon-triggered landslides 6 years after the earthquake. This study therefore demonstrates that an earthquake-induced model both sheds light on the environmental factors for triggering landslides, and augments a rainfall-induced model in its predictive capability in areas such as Taiwan.  相似文献