Fill Dam Research Articles

Effects of construction material properties on dam type selection (Sariguzel Dam – Turkey)

The availability of dam fill materials influenced the dam design considerably. Rockfill is one of the most preferred fill materials for embankment dam. Also, use of different fill material such as sand-gravel has been preferred in recent years. Previous studies on concrete-faced sand-gravel fill dam, results of the laboratory experiments and in situ testing analysis display that using sand-gravel as a fill material is not only cost-effective but also safe and provides high-quality natural construction material. This paper illustrates the importance of construction material properties on dam type selection. Sariguzel Dam is constructed on the Ceyhan River to the south-west of the Turkey. In the feasibility stage, the dam type was selected as the concrete-facing rockfill dam, depending on state of natural construction materials. Because of the inappropriate rock material quality, in design stage dam type was changed to concrete-faced sand-gravel fill type.

노후 코어형 필댐의 잠재 위해성 유형 분류

최근 국내 필댐 및 저수지의 노후화가 급속도로 진행되고 있으며, 이에 따른 제체의 손상이나 붕괴사고가 잇따르고 있다. 그러나 필댐의 핵심적인 차수기능을 담당하는 코어층에 대한 열화와 잠재 위해성 분류에 대한 연구는 거의 미진한 실정이다. 본 연구에서는 노후화가 진행 중인 13개 기존 코어형 필댐에 대해(준공 후 경과년수 9-52년, 댐 높이 22-67 m), 무수보링에 의한 코어층 시추 지반조사와 표준관입시험, 2D 및 3D 전기비저항탐사, 물성·역학시험을 수행하여 공학적 기반의 잠재적 위해성 유형을 국내 최초로 분류, 제시하였다. 중심코어층에 대한 무수보링 시추 지반조사 결과, 코어재 잠재 위해성 유형을 국부적 포화대, 신속한 공내수 유입, 조립질 혼재 코어재, 상대적 저 강성의 네 종류로 분류하였다. 코어형 필댐의 잠재 위해성 유형 중국부적 포화대 유형은 코어존 내 유로의 성장 및 발달에 의한 내적침식의 가능성이 존재하므로 가장 위험한 위해성으로 분류 되었으며, 코어재의 열화 등급에 따라 적절한 차수능 회복을 위한 보수보강이 필요한 것으로 판단되었다. 그 외 세 가지 위해성 유형은 즉각적인 조치보다는 지속적인 모니터링과 정기 검사의 강화가 필요할 것으로 검토되었다. 본 연구대상 댐의 분석 결과, 준공 후 경과년수와 댐 코어재의 열화 양상과는 상관성이 크게 없는 것으로 나타났다. 본 연구 결과는 코어형 필댐의 노후화에 따른 댐의 안전관리와 성능개선에 있어 유용한 자료로 활용 가능할 것으로 판단된다. As greater numbers of fill dams and reservoirs become old, the risks of damage or embankment collapse increases. However, few studies have considered the deterioration and hazard classification of the internal core layers of fill dams. This study reports the results of geotechnical investigations of 13 earth-cored fill dams in Korea, based on no-water borehole drilling, Standard Penetration Test, and 2D and 3D electrical resistivity surveys along with in situ and laboratory testing. High-capacity no-water boring minimized core layer disturbance while providing continuous core sample recovery. The results allow the classification of potential hazards related to the existing core layers based on both visual inspection of the recovered samples and the results of engineering surveys and tests. Four types of potential hazard are classified: locally fluidized core with a high water content, rapid water inflow to a borehole, cores with granular materials, and relatively low stiffness of core. Among these, the locally fluidized core is the most critical hazard that requires remedial action because it is related to the potential internal flow path and internal erosion. The other three hazard types are of medium importance and require careful monitoring and regular inspection. Of note, there was no correlation between age and core deterioration. The results are expected to aid the safe management and potential upgrading of aging cored fill dams.

중심코어형 필댐의 코어재 현장 물성에 대한 통계학적 분석

중심코어형 필댐의 코어재 현장 물성에 대한 통계학적 분석

여유고만으로 추정된 국내 재해위험 저수지의 지진시 파괴확률

본 연구의 목적은 소규모 필댐의 지진시 파괴확률을 산정하는 방법과 절차를 예시하고, 지반공학적 정보가 부족한 국내 재해위험 저수지의 지진시 파괴확률을 추정하는 것이다. 이를 위하여, 국내 재해위험 저수지로 지정된 저수지 중 지반공학적인 정보를 얻을 수 있는 7개 저수지에 대해 사건수 분석 기법을 적용하여 지진에 대한 파괴확률을 평가하였으며, 그 방법 및 절차를 예시하였다. 안전진단보고서를 확보한 84개 재해위험 저수지의 댐높이와 여유고와의 관계를 검토하였고, 미공병단 평가도구로 이용되는 파괴확률 산정식을 이러한 댐높이와 여유고와의 관계에 연관시켰다. 이러한 연관관계로부터, 지진시 파괴확률이 '0'이 되는 댐높이-여유고 임계곡선을 도출하였고, 이러한 임계곡선과 7개 저수지에 대해 산정한 지진시 파괴확률로부터 물성확보가 어려운 국내 재해위험 저수지의 개략적인 지진에 대한 파괴확률을 추정하였다. The objective of this study is to illustrate the methods and procedures for estimating the failure probability of small fill dams subjected to earthquake events and to estimate the seismic failure probability of the Korean disaster risk fill dams where geotechnical information is not available. In this study, first of all, seismic failure probabilities of 7 disaster risk small fill dams, where geotechnical information is available, were evaluated using event tree analysis. Also, the methods and procedures for evaluating probabilities are illustrated. The relationship between dam height and freeboard for 84 disaster risk small dams, for which the safety diagnosis reports are available, was examined. This relationship was associated with the failure computation equation contained in the toolbox of US Army corps of engineers. From this association, the dam height-freeborard critical curve, which represents 'zero' failure probability, was derived. The seismic failure probability of the Korean disaster risk fill dams was estimated using the critical curve and the failure probabilities computed for 7 small dams.

Execution Method for Spillway Hydraulic Surfaces: Upper Gotvand Dam

Abstrac t—Upper Gotvand Dam the largest rock fill dam of Iran is involved with several massive affiliated projects. 72m wide Spillway structure is 570m long from ogee to flip bucket with 4 radial gates, installed on ogee structure. 800000 m3 concrete is demanded to fulfill project most of which is required for hydraulic surfaces. Numbers of methods to accomplish various hydraulic surfaces are including screed pipe and manual trowelling, moving bar, and slip-form application. Facing technical as well as executive obstacles have brought out of several worthwhile conclusions. For instance, face has to be controlled in near edge for adjacent concrete before screed or mold installation. Conformity to proper executive sequences such as preparation, tool box installation, locating installation place for CJ molds, and then reinforcement has to be considered. Fulfilled surfaces have to be protected of either impact or any pollutants. Errors have to identify through comparison of surveys for performed surfaces with that of templates before placement, and then should be corrected in conjunction with adjacent blocks or next lifts. And to impede bolt displacement or shear occurrence, first hydraulic lift has to be casted using molds with no consoles.

1G場での振動実験による斜面模型の崩壊挙動の分析

1G場での振動実験による斜面模型の崩壊挙動の分析

Investigation on the resistant of tropical residual soils as clay core of rock fill dams against hydraulic fracturing

Investigation on the resistant of tropical residual soils as clay core of rock fill dams against hydraulic fracturing

Evaluation of seepage quantity of fill dam using 3D FEM analysis

Evaluation of seepage quantity of fill dam using 3D FEM analysis

Quick Triaxial Consolidated Drained Test on Gravelly Soil

Abstract Gravelly soil, a mixture of clay and gravel, has been widely used as a core material of high earth core rock fill dams. The triaxial consolidated drained (CD) test for gravelly soil is time-consuming, especially for larger scale test samples because of its low permeability caused by the high content of clay. This study presents a quick triaxial consolidated drained (QCD) test, which can greatly accelerate the CD test on gravelly soil. In the QCD test, the traditional cylindrical specimen was modified to a sand-core cylindrical specimen containing a hollow cylindrical specimen, and the sand column filled in the central hollow. As a result, the sand column in the center of the specimen greatly accelerates the water drainage of the specimen, and both the consolidation stage and the shear stage of the test can be finished quickly. Based on gravelly soil, the comparative tests, including CD tests and QCD tests, are performed. It is concluded that the QCD tests can be conducted more rapidly than CD tests, and the test results of QCD tests, for both stress–strain curves and the parameters of the Duncan–Chang model, are basically identical with that of the CD tests. The QCD test can greatly shorten the studying time on gravelly soil, i.e., the core material of earth core rock fill dams, thus speeding up the future design of dams.

FLOW AND DEFORMATION ANALYSIS OF ZONED EARTH DAM BY THE FINITE ELEMENT METHOD

A finite element method is practical and applicable for many fields including for geotechnical engineering structures. Seepage through earth dam is difficult to analyze especially dams with multiple zones. The problem becomes complex if it requires deformation analysis taking into account seismic conditions. Therefore, finite element is the best tool for analyzing seepage flow in an earth fill dam. The main objective of the paper is to simulate the seepage flow through an earth fill dam. Hassan Kanosh Dam which is located in the north eastern part of Iraq is chosen as a case study. There are three periods in the life of a dam which may be critical from the standpoint of shear failure and which must be analyzed; during construction condition, full reservoir condition, and rapid drawdown condition. The program SIGMA/W which is a finite element software coupled with SEEP/W, (another GEO-SLOPE software product) to analyze the dam. The stability analysis performed showed that all parts of the dam are safe within the prescribed rang of factors of safety for the possible loading and operation cases. It is recommended, however, that close control of the quality of the works during construction must be maintained to realize the shearing strengths necessary to fulfill the assumed strength and even more. It is recommended to check routinely the foundation conditions during excavation to realize the same end results.

Scale dependence of shear strength from direct shear test for a coarse granular material

Due to the excellent shear resistance, the coarse-grained soil often serves as a material of a filling structure like the embankment dam. However, the shear strength of this geomaterial measured by the direct shear test has obvious scale dependence. The scale effect needs to be eliminated when evaluating the shear strength parameters for design. This study employs a superimposition–nest type of direct shear apparatus to investigate the scale dependence of the shear resistance for a natural coarse granular material, which will be used as a filling material of the rock fill dam in a hydropower station. The present apparatus can vary the diameter and height of specimen. The gap thickness can be kept constant during shearing. There are seven sets of different size tests performed in total. The variations of the shear strength indices plotted according to the test results reveal the influence of the specimen size on the soil shear resistance. The mechanism of the scale effect is discussed, and the lower limits of the diameter and height of specimen as well.

Predicting shear strengths of mine waste rock dumps and rock fill dams using artificial neural networks

Three new back-propagation artificial neural networks (ANNs) for predicting the shear strength envelopes of mine waste rock dumps and rock fill dams are presented. Fourteen key material properties for rock fill characterisation are mustered for model development and evaluation. Using principal component analysis, the initial fourteen parameters are ultimately reduced to six through data compression. The neural net with the fewest parameters (ANNOPTC) is consistent over the widest range of confining stresses for shear strength prediction. The three artificial neural networks also perform better than multiple regression conducted on the same global database. Sensitivity analysis ranks input parameters as normal stress, minimum particle strength, dry unit weight, 10% passing sieve size, the coefficient of curvature of the particle size distribution, and the coefficient of uniformity of the particle size distribution in decreasing order of significance. Excellent agreement is observed between predicted and measured shear strengths for new cases.

Simplified Seismic-stability Analysis of Small Earth Fill Dams against Level 2 Seismic Load

Simplified Seismic-stability Analysis of Small Earth Fill Dams against Level 2 Seismic Load

Seismic-stability Analysis of Small Earth Fill Dams by Newmark-D Method

Seismic-stability Analysis of Small Earth Fill Dams by Newmark-D Method

Stress-path on the Hydraulic Fracturing Test of the Clay Core of Rock Fill Dams in the Laboratory

Hydraulic fracturing on the rock fill dam is described as a phenomenon of cracks on the upstream face of clay core of rock fill dams due to the tension failure. This situation may arise if the total stress in the core is reduced by arching effect and increasing pore water pressure in the core during impounding. Hydraulic fracturing on the rock fill dams can be modelled in the laboratory. The reduction of the total overburden stress due to arching effect and hydraulic pressure from the water in the reservoir can be modeled in the laboratory by applying the initial stress states and water pressure to the specimens. The soil specimens were compacted in a hollow cylinder. The dimension of the soil specimen was 100mm in diameter and 120mm high, while the inner diameter of the borehole was 18mm. The paper present an initial hydraulic fracturing test at 5 (five) different initial stress states in order to investigate the tension fracture mechanism. The stress paths during hydraulic fracturing tests indicated the tension fracture to the soil specimens occurs on the soil specimens which the initial stresses fall in the envelope of ½(σy - σx) < c.

Adequacy of Seepage Analysis in Core Section of the Earthen Dam with Different Mix Proportions

Earthen dams are built since early days of civilization. These dams constitute to be the most common type, because it is generally built of locally available materials which derive strength from their position, friction and cohesion. Many earth fill dams are vulnerable to failures due to seepage problems that take place in the core since all soils are pervious to a smaller or larger extent. One of the ways to control seepage problem in earthen dam is by using proper materials for core section since the core section of earthen dam provides impermeable barrier within the body of the dam. Thus, this paper analyses the usage of various materials with different combinations to zone type earthen dams with central impervious vertical core and to study the behavior of phreatic line at downstream phase by varying effective length of horizontal drainage filter. The results obtained from laboratory, proposed geometry of dam and corresponding stability analysis made for various materials showed that materials with impervious nature only provides safety to core part of the earthen dam

The Limit Equilibrium Method in the Application of Earth-Rock Fill Dams Reinforcement

Limit equilibrium method is commonly used earth-rock fill dams stability calculation method in engineering, this article simply introduces the basic principle of limit equilibrium method, and through a practical project introduced the methods in the application of earth-rock fill dams reinforcement, and achieved good effect.

Multifunctional Use of Self-Compacting Concrete as A Fundamental Material in Dam Construction: Upper Gotvand Dam

Contemporary knowledge of SCC concretes, that brought about of worthy endeavors of numerous researcher and engineers have come in handy now.Taking advantage of such material makes compound construction more efficient, easier and less expensive. Upper Gotvand , a 180 meters height rock fill dam located southwestern Iran have several affiliated projects using SCC concrete for their high reinforced or hard to access segments such as bottom outlet structure, pressure tunnel blocks, concrete coating for penstock steel lining, upper and lower bends, powerhouse structures and etc. Particular structural peculiarities for each individual projects have been detected as well and SCC-related conclusions were made. To satisfy essential needs in order to make this concrete more ideal we are about to study mix design components to select the most consistent ingredients. Different available cements, third generation admixtures, and aggregate sources interaction were explored to elicit the most optimized mix design, native to region. In this article, accomplished quality control tests have been introduced. Test results have led to satisfactory mix manipulation and to ensure optimized attributes for required practical applications. It was revealed among Gotvand SCC ingredients, Binders and fines are the most ruling components, capable of governing practical traits. River aggregates are highly beneficial and Gelenium51P acts consistently with Ilam cement. Assigned Q.C. tests have led us to favorite mix named, NA45. Because of higher lateral pressure of fresh SCC than ordinary concrete, it was allocated to heading and upper lifts of walls. More water proof forms and more support requirement as well as longer setting time were concluded as relative constraints of SCC at practice.

Research and Application on Concrete Face Rock-Fill Dam’s Earth-Rock Allocation

The earth-rock allocation is the core problem affecting the overall situation of the rock fill dam construction, how to reasonable and effective for earth-rock allocation implementation is directly related to the project schedule, quality and economic goals. Through systematic analysis of rock-fill dam’s earth-rock allocation determine the features of excavation project, reclamation projects, excavation yard, debris field, transit field, and define the relationship between the various sectors of excavation, filling, transit, debris, mining and other aspects of rock-fill dam’s earth-rock allocation. Use the minimum value of the allocation sum cost as the objective function, combined with the qualitative and quantitative constraints in allocation process to build earth-rock allocation models. According to the established model, combining the actual project, based on the VS2008, develop a rock-fill dam’s earth-rock allocation system. Detailed simulate the process of rock-fill dam’s earth-rock allocation, and take charts to show intuitively.

Stability Evaluation of Fill Dam in Graphite Mine Tailings Impoundment

The graphite mine tailings impoundment was detailed investigated, and the structural features of fill dam in the graphite mine tailings impoundment was analyzed. Then the author created the stability calculating model of this fill dam, calculated its stability coefficient, and evaluated its stability. It can be concluded that: the fill dam was stable under the condition of normal operation, and it was unstable under the condition of flood operation and special operation.