Thermal-Structural Modeling and Temperature Control of Roller Compacted Concrete Gravity Dam

The knowledge of the behavior of any roller compacted concrete (RCC) dam and its foundation is gained by studying the service action of the dam and its foundation using measurements of an external and internal nature. The information by which a continuing assurance of structural safety of the RCC dam can be gauged is of primary importance. Similarly, the fact that the information on structural and thermal behavior and the properties of concrete that may be used to give added criteria for use in the design of future RCC dams is of secondary importance. Wide spread attention is now being given to the installation of more expensive instrumentation for studying the behavior of concrete dams and reservoirs and forecasting of any adverse trends. In view of this, the paper traces installation and need of the comprehensive instrumentation scheme implemented to monitor the structural and thermal behavior of 102.4 m high RCC dam constructed near Mumbai in India. An attempt is made in the present paper to emphasize the need to undertake an instrumentation program and evaluate their performance during construction and post construction stage of RCC structures. Few typical results, regarding the thermal and structural behavior of the dam, obtained through instrumentation installed at the dam site are presented and compared with the design considerations. The fair agreement is seen in the response observed through instrumentation with that governing the design criteria.

The response surface approach is cooperated with the finite step method for the fitting of explicit performance function and reliability index calculation, which can make the system reliability analysis and failure path analysis of complex structures very easy. The failure path, functionality failure mode and corresponding reliability system index of Longkaikou roller compacted concrete gravity dam is studied. Different failure paths for dam, rock and roller compacted concrete layers are searched, and the corresponding explicit failure mode or performance functions for different function such as limit loads state are obtained with Response Surface Method for the subsequent reliability index calculation with Finite Step Method. And based on the theory of system reliability, the failure probability and reliability of the whole dam are obtained. The validity of proposed method is verified.

The main objective of this study is to present a method of determining viscoelastic deformation monitoring index of a Roller-compacted concrete (RCC) gravity dam in an alpine region. By focusing on a modified deformation monitoring model considering frost heave and back analyzed mechanical parameters of the dam, the working state of viscoelasticity for the dam is illustrated followed by an investigation and designation of adverse load cases using orthogonal test method. Water pressure component is then calculated by finite element method, while temperature, time effect, and frost heave components are obtained through deformation statistical model considering frost heave. The viscoelastic deformation monitoring index is eventually determined by small probability and maximum entropy methods. The results show that (a) with the abnormal probability 1% the dam deformation monitoring index for small probability and maximum entropy methods is 23.703 mm and 22.981 mm, respectively; thus the maximum measured displacement of the dam is less than deformation monitoring index, which indicates that the dam is currently in a state of safety operation and (b) the obtained deformation monitoring index using orthogonal test method is more accurate due to the full consideration of more random factors; the method gained from this study will likely be of use to diagnose the working state for those RCC dams in alpine regions.

The freezing and thawing durability of Norway's first Roller Compacted Concrete (RCC) dam was studied using the Scandinavian slab test (European/CEN test method for freezing and thawing durability) and ASTM C671 freezing dilation test. RCC with W/(C+FA) = 0.53 and FA/(C+FA) = 0.67 had some scaling and severe internal cracking in the wet freezing and thawing exposure of the slab test. The period of freezing and thawing immunity of RCC in the separated absorption and sealed freezing procedure of the dilation test was shorter than that of the conventional facing concrete (FC). Air entraining improved the RCC's freezing and thawing resistance, although not to be as good as that of FC with W/(C+FA) = 0.50 and FA/(C+FA) = 0 and 0.40. The FC had low scaling and no sign of internal cracking in the slab test, and the RCC's period of freezing and thawing immunity was longer than the 120 days of absorption used in the dilation test. The air voids of the RCC were coarser and the protective share of voids (= voids that are not filled by capillary suction but filled by 10 MPa pressure head) was lower than in the FC. Critical degrees of saturation were determined for service life prediction by combining dilation- and degree of saturation measurements.

The roller compacted concrete gravity dam is poured by thin layers and there are many horizontal layer surfaces and joint surfaces in the dam. The shear strength of these surfaces is obviously lower than that of the RCC concrete. These horizontal layer surfaces and joint surface are the key positions affecting the strength, stability and seepage of the dam. The height of the most RCC gravity dams is about 100m. The height is relatively low and the horizontal thrust is relatively small. So anti-sliding stability issue along the layer surfaces has not attracted enough attention. But for the dams 200m high, this problem is very prominent. In this study, using an isotropic damage model, based on the effective stress principle of porous media, taking the stress-seepage-damage coupling effect into account, the failure mechanism of Huangdeng RCC gravity dam is discussed. The results show that the failure mechanism of RCC gravity dam is the shear slipping along the layer surfaces and the foundation surface.

Comision Federal de Electricidad has coal fired power plants in the states of Coahuila and Guerrero, in Mexico. They have production capacities of 2600 and 2100 megawatts respectively, and together they can consume more than 12 million tons of coal every year. During the electricity production process, 12% of the coal remains as ashes and its disposal is expensive. From those residues it is possible to use the fly ash, which represents about 80% of these ashes. Fly ashes have been used for several construction purposes, including the improving of concrete (as an addition). The construction of Roller Compacted Concrete (RCC) dams has been increasing around the world, and Mexico is evaluating these kinds of projects. The use of fly ash (from the Guerrero power plant) on the RCC mixtures is an option that can reduce the amount of cement, decreasing the heat of hydration and improving other characteristics as well.

Study on real-time construction quality monitoring of storehouse surfaces for RCC dams

Implementation of BIM + WebGIS Based on Extended IFC and Batched 3D Tiles Data: An Application in RCC Gravity Dam for Republication of Design Change Model

Seismic analysis of Roller Compacted Concrete (RCC) dams considering effect of sizes and shapes of galleries

The existing Scoggins Dam and reservoir are in Washington County, Oregon, and the title is held by the U.S. Bureau of Reclamation (Reclamation). Reclamation has previously identified dam safety concerns related to the existing embankment dam. Regional project sponsors, including Clean Water Services, have identified the need for expanded storage capacity in the reservoir to meet growing water demands and address water quality issues in the Tualatin River downstream of the dam. As part of efforts to resolve dam safety issues and increase the water storage in the reservoir, a comprehensive feasibility level design of a new 185-foot-high Roller Compacted Concrete (RCC) dam. Extraordinary seismic hazards have been identified in the region associated with the Cascadia Subduction Zone (CSZ). Further, any dam alternative carried forward for funding, final design, and construction will have to meet the Public Protection Guidelines (PPG) of Reclamation that require a formal quantitative risk analysis. A risk-informed design approach was adopted to configure the layout and cross-section properties of the dam. A multi-phase site characterization program and preliminary RCC mix design program were performed to support the design. In addition, models were developed, and an extensive suite of both (two-dimensional) 2D and (three-dimensional) 3D structural analyses were performed for seismic loadings with total durations of over 200 s, strong shaking of over 140 s, and peak ground accelerations of over 2 gravitational accelerations (g) (up to 50,000-year return period event). This paper describes the feasibility design configuration of the dam, including the seismic hazard characterization, structural analysis models, and seismic response modeling results. The expected performance of the dam relative to the risk-informed design criteria and Reclamation PPGs will be generally described.

This paper presents a mathematical model about the temperature regime and thermal stress state of Ban Lai roller-compacted concrete gravity dam, built in the climatic conditions of northern Vietnam. The model is made on the basis of the finite element method using the software complex Midas Civil. The three cases of dam construction were considered: The first was construction progress with 0.3 m/day, the second was construction process with 0.4 m/day and the last was actual construction progress. The results obtained from the mathematical model compared to the field measurements are reliable. This allows us to recommend the use of the proposed methodology with similar objects. The obtained values of maximum temperatures and thermal stresses indicate a low probability of temperature cracks.

Roller-compacted concrete (RCC) is widely used for industrial and heavy-duty pavements. An economical and durable material for paving and other applications, RCC has a high strength and a high density. Although the strength of RCC has been thoroughly investigated, the freeze–thaw durability of RCC remains a topic of contention. RCC has often performed well in harsh field environments, but it frequently fails laboratory freeze–thaw durability testing. In this study, 24 specimens were fabricated for freeze–thaw durability testing with a gyratory compactor. The study variables were the degree of compaction, the amount of water, and the water-to-cement (w/c) ratio (and, hence, the amount of cement). The specimens replicated the concrete found in typical RCC pavement and dam construction. The RCC specimens were subjected to up to 300 cycles of rapid freezing and thawing and were tested for fundamental transverse frequency and mass loss. Because of the low aspect ratios of the specimens, fundamental transverse frequency testing was not reliable. Several specimens completed the 300 cycles with a mass loss of less than 10%. The freeze–thaw durability of RCC was found to be dependent primarily on the amount of cement paste and the w/c ratio and to a lesser extent on the degree of compaction.

The strain softening characteristics of the roller-compacted concrete (RCC) level is a key condition in studying the bearing capacity of RCC dam. Assuming that the RCC dam unit is in the adiabatic condition, horizontal and vertical linear expansion coefficients of the RCC level are calculated. These methods were applied in practical engineering, and equivalent thermodynamic parameters can be obtained by taking the weighted squared residuals between numerical values and monitoring data as the optimization objective function in parameter inverse analysis. And the difference of the Poisson ratio and the elastic modulus, the hampering of the ontology on the layer could be reflected accurately.

The Grand Ethiopian Renaissance Dam is the first major dam in the Blue Nile (Abay) River of Ethiopia. GERD is a combination of 175 m high roller compacted concrete gravity dam and a 50 m high concrete faced rock fill saddle dam under construction by Ethiopia. The gravity dam is built across the natural course of the Blue Nile River and the saddle dam provides the design storage and water level due to the relatively low relief of the dam site. The dam is being built at the most downstream site of one of the four potential dam sites proposed by a 1964 feasibility study of the Blue Nile basin development conducted by United States Bureau of Reclamation. The dam has been under construction since 2011 with 70% completed at the beginning of 2018. The installed power generation capacity of 6,000 MW is expected to be generated by 16 Francis Turbines each with 375 MW capacity located at the foot of the main dam. The design flow rate of 4305 m3 s−1 is about 3 times the average flow. At the average flow rate, the expected average annual energy production is 15,700 GWH. The suitability of the dam site, dam design, major components and operations are discussed.

Study of failure mechanism of roller compacted concrete gravity dam (in Chinese) : Duan Yahui & Lai Guowei, Shuili Xuebao/Journal of Hydraulic Engineering, 5, 1995, pp 55–59