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3.
The present study attempts to predict the reservoir sedimentation in 32 km region of the Tenryu River between the Hiraoka and Sakuma Dams in Japan. For numerical simulations of the reservoir sedimentation, the one-dimensional model of the Hydrologic Engineering Centre-River Analysis System (HEC-RAS) is used together with the inclusion of channel geometry, bed gradation curve, Exner-5 bed sorting mechanisms, fall velocity of the particle, and flow and sediment boundary conditions pertaining to modeling region. The modeling region of the Tenryu River is divided into 48 river stations with 47 reaches in the numerical simulations. The numerical model is calibrated using the available data for 48 years from 1957 to 2004. The formulae of sediment transport function, Manning’s roughness coefficient, computational increment and fall velocity have been identified for getting the best estimation of the Sakuma Dam reservoir sedimentation. Combination of obtained sensitive parameters and erodible limits of 2 m gave the best comparison with the measured bed profile. The computed results follow the trend of measured data with a small underestimation. Although Manning’s roughness coefficient has an effect on the sedimentation, no direct relation is found between the Manning’s roughness coefficient and reservoir sedimentation. It is found that the temperature of water has no effect on the reservoir sedimentation. 相似文献
4.
The Tabarak Abad Dam on the river Tabarak, a branch of Atrak river, is located about 25 km of northeast of Quchan city in the northeast of Iran. The dam is now under construction and will be completed in 2002. The Tabarak Abad Dam has been designed as an earthfill dam with a clay core. The dam and its associated concrete structures are mainly founded on limestone and shale of the Shoorigeh formation of Upper Jurassic to Lower Cretaceous age and limestone and sandstone of the Tirgan formation of Lower Cretaceous age. These rocks are affected by high jointing and faulting especially in the surface. This paper discusses the site investigation for the dam. 相似文献
6.
Embankment dams are one of the most important geotechnical structures that their failures can lead to disastrous damages. One of the main causes of dam failure is its slope instability. Slope Stability analysis has traditionally been performed using the deterministic approaches. These approaches show the safety of slope only with factor of safety that this factor cannot take into account the uncertainty in soil parameters. Hence, to investigate the impact of uncertainties in soil parameters on slope stability, probabilistic analysis by Monte Carlo Simulation (MCS) method was used in this research. MCS method is a computational algorithm that uses random sampling to compute the results. This method studies the probability of slope failure using the distribution function of soil parameters. Stability analysis of upstream and downstream slopes of Alborz dam in all different design modes was done in both static and quasi-static condition. Probability of failure and reliability index were investigated for critical failure surfaces. Based on the reliability index obtained in different conditions, it can be said that the downstream and upstream slope of the Alborz dam is stable. The results show that although the factor of safety for upstream slope in the state of earthquake loading was enough, but the results derived from probabilistic analysis indicate that the factor of safety is not adequate. Also the upstream slope of the Alborz dam is unstable under high and uncontrolled explosions conditions in steady seepage from different levels under quasi-static terms. 相似文献
7.
Talbingo Dam is a well instrumented, 162m high rockfill structure with an upstream sloping silty clay core, located in the southern New South Wales, Australia. A non-linear finite element analysis of its behaviour was carried out under plane strain conditions, simulating its construction, reservoir filling and steady seepage loading stages. Material parameters are determined from triaxial tests on the rockfill, core, filter and transition materials, compacted to field dry density and moisture content. All materials show non-linear stress–strain behaviour, with rockfill exhibiting work softening at large strain. Mohr envelopes for rockfill are slightly curved but linear approximations are acceptable. When compared with stresses and deformations at maximum cross section, the analytical results show good agreement in most areas. A non-linear model for pore pressure response is used successfully to predict the high pore pressures in the lower region of the core. A stability analysis performed for the end of construction stage, based on finite element stresses, shows that the design safety factors are slightly conservative. 相似文献
8.
This paper reviews the events leading to the failure of Teton Dam in Idaho on June 5, 1976 and the investigations, conducted over a period of about eight years, to determine the cause of the failure. Conclusions are presented regarding the probable trigger mechanisms which initiated the failure, the mechanics of failure and the significant lessons concerning earth dam design and construction resulting from the investigations. 相似文献
11.
The Urft dam is an old German gravity dam located in the Eifel near Cologne. In order to ensure its stability and for adjustment to today??s technical standards rehabilitation works were required. Two inspection galleries were excavated below the storage level by means of smooth blasting. To reduce the porewater pressure acting on the dam??s base and thus to increase the stability of the dam also the drainage system was reconstructed and improved. Because the Urft dam is curved, its load bearing behavior reveals a certain arching effect. In order to take advantage of this arch action the stability proof was carried out by means of three-dimensional analyses according to the FEM. In these analyses the interaction of dam and the foundation rock was accounted for. Explorations, laboratory and in situ testing of the masonry and the foundation rock were carried out and a monitoring program was established. The monitoring results allowed a calibration of the three-dimensional model for stability analyses by means of back analyses. On this basis the final stability proof could be conducted. 相似文献
13.
三峡工程建成后,三峡-葛洲坝之间的河段是宜昌至重庆河段船舶航行最困难的航段之一.建立了该河段的三维水流数值模型,计算三峡不同下泄流量下的三维流场,并根据计算结果与适航条件分析其适航区域.研究结果表明,当下泄流量不大于25 000 m3/s时,两坝间河段基本能满足万吨级船队的通航水流条件;当流量大于此值时,将会出现碍航区域,且随流量的增加,万吨级船队通航水流条件逐渐恶化.若适当提高通航标准,则通航流量可加大到45 000 m3/s. 相似文献
14.
This paper describes the results of the engineering geological investigations and rock mechanics studies carried out at the proposed Uru
Dam site. Analyses were carried out in terms of rock mass classifications for diversion tunnel, kinematic analysis of excavation slopes, permeability of the dam foundation and determination of rock mass strength parameters.Uru
Dam is a rock-filled dam with upstream concrete slab. The dam will be built on the Suveri River in the central part of Turkey. The foundation rocks are volcanic rocks, which consist of andesite, basalt and tuff of Neogene Age. Studies were carried out both at the field and the laboratory. Field studies include engineering geological mapping, intensive discontinuity surveying, core drilling, pressurized water tests and sampling for laboratory testing.Uniaxial, triaxial and tensile strength tests were performed and deformation parameters, unit weight and porosity were determined on the intact rock specimens in the laboratory. Rock mass strength and modulus of elasticity of rock mass are determined using the Hoek–Brown empirical strength criterion. Rock mass classifications have been performed according to RMR and Q systems for the diversion tunnel.Engineering geological assessment of the proposed dam and reservoir area indicated that there will be no foundation stability problems. Detailed geotechnical investigations are required for the final design of the dam. 相似文献
15.
This paper attempts to put together details of dams’ development in Nigeria. Case studies of dam-related incidents were highlighted.
A typical case study of Kainji dam safety monitoring assessment was analysed and discussed. From the results obtained it is
observed that majority of the piezometer plot of the spillway points to improving stability especially from year 2000 to 2001.
The data collected and analysed indicated some displacement of about 25 mm. in some blocks, which shows an abnormal behaviour
and require need for closer observations. The tape extensometers reading and the rod extensometer were briefly discussed. 相似文献
17.
抛石固岸是崩岸除险的一种常用方法,本文结合江西马当长江堤防加固工程介绍该施工技术. 相似文献
19.
This paper describes the seepage prevention measures at Kalecik Dam. Water leaked from the foundation of the dam after the impoundment. The dam, 77 m in height, was constructed for irrigation purposes. The foundation consists of Mesozoic ophiolite, Paleocene allochthonous units composed of different lithologies and Miocene conglomerate. Karstified and fractured Paleocene limestone outcrops on the right bank of the dam foundation. This unit extends into, and its thickness increases within, the right abutment. The leakage occurs towards the downstream springs through the right bank limestone. The main grout curtain is 200 m long and 60 m deep and was constructed on the right bank. After reservoir impounding, new springs were observed in the downstream area. Therefore, after the construction of the dam, remedial curtain grouting was required and carried out in three stages. Firstly, the main grout curtain was supplemented by additional grouting to seal the fractures and infill karstic cavities. The diversion tunnel was also repaired. The curtain depth was the same as the depth of the previous curtain. The second stage of additional treatment consisted of new deep grouting. Some investigation holes were also drilled along the same alignment as the main curtain to locate the seepage in the region. These holes were extended to an elevation of 442 m. The final stage of grouting measures was between the spillway and the dam body and underneath the spillway. As a result of the additional grouting measures, the spring discharges observed downstream of the dam embankment decreased. However, the seepage paths were extended and were moved with time so that the seepage problems are still continuing. 相似文献
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