基于分布式光纤传感的堤坝安全监测技术及展望          下载免费PDF全文

冷元宝  朱萍玉  周杨  王送来 《地球物理学进展》2007,22(3):1001-1005

及时、准确地掌握堤坝的性态，是保证堤坝安全运行的基础.因此，需要一种实时监测系统对堤坝进行监测.分析了堤坝健康监测的主要内容，介绍了分布式光纤传感技术的工作原理及使用现状；探讨了分布式光纤传感技术在我国堤坝渗流和形变中的应用；指出了分布式光纤传感技术在土堤坝使用中存在的问题，并给出了新的堤坝长期安全监测系统设计建议，结论有益于指导构建新的基于分布式光纤技术的堤坝安全监测系统.  相似文献   

Seismic fragility assessment of concrete gravity dams     

Paulos B. Tekie  Bruce R. Ellingwood 《地震工程与结构动力学》2003,32(14):2221-2240

Many concrete gravity dams have been in service for over 50 years, and over this period important advances in the methodologies for evaluation of natural phenomena hazards have caused the design‐basis events for these dams to be revised upwards. Older existing dams may fail to meet revised safety criteria and structural rehabilitation to meet such criteria may be costly and difficult. Fragility assessment provides a tool for rational safety evaluation of existing facilities and decision‐making by using a probabilistic framework to model sources of uncertainty that may impact dam performance. This paper presents a methodology for developing fragilities of concrete gravity dams to assess their performance against seismic hazards. The methodology is illustrated using the Bluestone Dam on the New River in West Virginia, which was designed in the late 1930s. The seismic fragility assessment indicated that sliding along the dam–foundation interface is likely if the dam were to be subjected to an earthquake with a magnitude of the maximum credible earthquake (MCE) specified by the U.S. Army Corps of Engineers. Moreover, there will likely be tensile cracking at the neck of the dam at this level of seismic excitation. However, loss of control of the reservoir is unlikely. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

修筑寒区小型水利工程的经验回顾     

Rudolf V. Zhang 《冰川冻土》2004,26(Z1):12-20

The paper provides a review of experience with the construction of hydraulic projects in the permafrost regions. Principles for construction, operation and maintenance of earth dams are refined and formulated. High priority needs for improving the stability of structures are identified.  相似文献   

Continuous ambient‐vibration monitoring of the arch dam of Mauvoisin     

Georges R. Darbre  Jean Proulx 《地震工程与结构动力学》2002,31(2):475-480

This paper presents the experimental programme and results of a continuous ambient vibrations recording programme carried out on the 250 m arch dam of Mauvoisin. This project follows a series of previous measurements completed for seven different water levels. An automated system was set up on the dam and the ambient vibrations were recorded twice daily for a period of 6 months. Frequency shifts were tracked throughout the testing period and the effects of the varying water level were identified. The results confirmed the behaviour observed in previous ambient‐ and forced‐vibration tests. The added‐mass effects are overcome by the stiffening of the dam due to increasing hydrostatic pressure for lower reservoir levels. This trend is then reversed for higher water levels. Any temperature‐related effects were not identified. The experimental techniques are briefly described and the frequency identification process and its limitations are discussed. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

An experimental evaluation of ice cover effects on the dynamic behaviour of a concrete gravity dam     

Patrick Paultre  Jean Proulx  Charles Carbonneau 《地震工程与结构动力学》2002,31(12):2067-2082

An extensive forced‐vibration testing programme has been carried out on an 84‐m concrete gravity dam located in northeastern Québec, Canada. The dam was subjected to a harmonic load on the crest in summer and severe winter conditions with temperatures ranging from ?10°C to ?15°C and a 1.0–1.5m ice cover. Acceleration and hydrodynamic frequency responses were obtained in different locations on the dam and in the reservoir. The main objective of the repeated tests was to investigate the effects of the ice cover on the dynamic behaviour of the dam–reservoir–foundation system, by comparing summer and winter results. Modifications in damping and resonance frequencies were observed, as well as an additional resonance that was attributed to an interaction of the dam with the ice cover. These findings provided a reliable and unique database for the investigations of dam–reservoir–foundation interaction and, in particular, the ice‐cover effects for dams located in northern regions. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

活动断裂的可变破裂尺度地震行为与级联破裂模式的应用.   总被引：17，自引：2，他引：17       下载免费PDF全文

闻学泽 《地震学报》2001,23(4):380-390

初步揭示出中国大陆地区活动断裂的地震破裂尺度可变行为，即在同一断裂部分不同轮回的破裂规模是不同的，因而地震强度也随时间变化．这种变化的趋势不具必然性．根据定义的相对破裂规模，统计表明:两相继轮回的破裂规模相同的概率最小．当前一轮回的破裂规模为小时，后一轮回的趋于大的概率为0.48；当前一轮回的破裂规模为中时，后一轮回的趋于小和大的概率分别为0.69和0.25；当前一轮回的破裂规模为大时，后一轮回的趋于大的概率为0，而趋于小和中的概率分别为0.36和0.64．笔者引入并完善了级联破裂模式，用于描述同一断裂部分破裂尺度的可变性和复杂性．在总结已发生过级联破裂的走滑活动断裂基本特征的基础上，提出这类断裂的级联破裂分段的原则．作为应用举例，对川西安宁河断裂带的一部分进行了级联破裂分段，并进而评估了未来地震的可能强度以及其对应的概率．   相似文献   

Assessing the TOPKAPI non‐linear reservoir cascade approximation by means of a characteristic lines solution     

Zhiyu Liu  Ezio Todini 《水文研究》2005,19(10):1983-2006

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大型泄洪洞有压弯道水力特性          下载免费PDF全文

沙海飞  吴时强  周辉 《水科学进展》2009,20(6):824-829

为系统研究泄洪洞有压弯道的水力特性,结合大比尺物理模型,采用三维Reynolds应力数学模型(RSM)对不同来流流速、弯曲半径和转角的有压弯道进行了计算,用模型试验资料对弯道的压力和流速分布进行了验证,计算值和试验值吻合良好。给出了弯道的内外压差和最低压力的规律、二次环流的发生和发展过程,弯道的水力特性和弯曲半径关系较大,并提出了一些工程措施。  相似文献   

Modelling the impact of land-use change and farm dam construction on hillslope sediment delivery to rivers at the regional scale     

Gert Verstraeten  Ian P. Prosser 《Geomorphology》2008,98(3-4):199

Landscapes in southeastern Australia have changed dramatically since the spread of European colonisation in the 19th century. Due to widespread forest clearance for cultivation and grazing, erosion and sediment yields have increased by a factor of more than 150. In the 20th century, erosion and sediment yield were reduced again due to an increasing vegetative cover. Furthermore, during the last decades, thousands of small farm dams were constructed to provide drinking water for cattle. These dams trap a lot of sediment, thereby further reducing sediment delivery from hillslopes to river channels. Changes in sediment delivery since European colonisation are documented in sediment archives. Within this study, these changing rates in hillslope erosion and sediment delivery were modelled using a spatially distributed erosion and sediment delivery model (WATEM/SEDEM) that was calibrated for Australian ecosystems using sediment yield data derived from sedimentation rates in 26 small farm dams. The model was applied to the Murrumbidgee river basin (30,000 km²) under different land-use scenarios. First, the erosion and sediment yield under pre-European land-use was modelled. Secondly, recent land-use patterns were used in the model. Finally, recent land-use including the impact of farm dams and large reservoirs was simulated. The results show that the WATEM/SEDEM model is capable of predicting the intensity of the geomorphic response to changes in land-use through time. Changes in hillslope erosion and hillslope sediment delivery rates are not equal, illustrating the non-linear response of the catchment. Current hillslope sediment supply to the river channel network is predicted to be 370% higher compared to the pre-European settlement period, yet farm dams have reduced this back to 2.5 times the pre-19th century values. The role of larger reservoirs is even more important as they have reduced the current sediment supply downstream to their pre-European values, thus completely masking the increased hillslope erosion rates from land-use change. However, the model does so far not include valley widening and sediment storage in river systems. Therefore, modelled rates of sediment delivery are lower than observed values.  相似文献   

A grassed waterway and earthen dams to control muddy floods from a cultivated catchment of the Belgian loess belt     

Olivier Evrard  Karel Vandaele  Bas van Wesemael  Charles L. Bielders 《Geomorphology》2008,100(3-4):419-428

Muddy floods, i.e. runoff from cultivated areas carrying large quantities of soil, are frequent and widespread in the European loess belt. They are mainly generated in dry zero-order valleys and are nowadays considered as the most likely process transferring material eroded from cultivated hillslopes during the Holocene to the flood plain. The huge costs of muddy flood damages justify the urgent installation of control measures. In the framework of the ‘Soil Erosion Decree’ of the Belgian Flemish region, a 12 ha-grassed waterway and three earthen dams have been installed between 2002–2004 in the thalweg of a 300-ha cultivated dry valley in the Belgian loess belt. The measures served their purpose by preventing any muddy flood in the downstream village, despite the occurrence of several extreme rainfall events (with a maximum return period of 150 years). The catchment has been intensively monitored from 2005–2007 and 39 runoff events were recorded in that period. Peak discharge (per ha) was reduced by 69% between the upstream and the downstream extremities of the grassed waterway (GWW). Furthermore, runoff was buffered for 5–12 h behind the dams, and the lag time at the outlet of the catchment was thereby increased by 75%. Reinfiltration was also observed within the waterway, runoff coefficients decreasing by a mean of 50% between both extremities of the GWW. Sediment discharge was also reduced by 93% between the GWW's inflow and the outlet. Before the installation of the control measures, specific sediment yield (SSY) of the catchment reached 3.5 t ha^− 1 yr^− 1 and an ephemeral gully was observed nearly each year in the catchment. Since the control measures have been installed, no (ephemeral) gully has developed and the SSY of the catchment dropped to a mean of 0.5 t ha^− 1 yr^− 1. Hence, sediment transfer from the cultivated dry valley to the alluvial plain should dramatically decrease. Total cost of the control measures that are built for a 20 year-period is very low (126 € ha^− 1) compared to the mean damage cost associated with muddy floods in the study area (54 € ha^− 1 yr^− 1). Similar measures should therefore be installed to protect other flooded villages of the Belgian loess belt and comparable environments.  相似文献