Research on Hydraulic Characteristics in Diversion Pipelines under a Load Rejection Process of a PSH Station

Transient analysis in diversion pipelines should be performed to ensure the safety of a hydropower system. After the establishment of a three-dimensional (3D) geometric model from the part upstream reservoir to the diversion pipeline end in a pumped storage hydropower (PSH) station, the hydraulic characteristics of the diversion system were solved by Reynold average Navier&ndash Stokes (RANS) equations based on a volume of fluid (VOF) method under the condition of simultaneous load rejection of two units. The variations of the water level in the surge tank, the pressure at the pipeline end, and the velocity on the different pipeline sections with time were obtained through the calculation. The numerical results showed that the water level changing in the surge tank simulated by VOF was consistent with the field test data. These results also showed that a self-excited spiral flow occurs in the pipeline when the flow at the end of the pipeline was reduced to zero and its intensity decreased with the flow energy exhaustion. The discovery of the self-excited spiral flow in the study may provide a new explanation for the pressure wave attenuation mechanism. Document type: Articl

Green Low-Carbon Technology for Metalliferous Minerals

Metalliferous minerals play a central role in the global economy. They will continue to provide the raw materials we need for industrial processes. Significant challenges will likely emerge if the climate-driven green and low-carbon development transition of metalliferous mineral exploitation is not managed responsibly and sustainably. Green low-carbon technology is vital to promote the development of metalliferous mineral resources shifting from extensive and destructive mining to clean and energy-saving mining in future decades. Global mining scientists and engineers have conducted a lot of research in related fields, such as green mining, ecological mining, energy-saving mining, and mining solid waste recycling, and have achieved a great deal of innovative progress and achievements. This Special Issue intends to collect the latest developments in the green low-carbon mining field, written by well-known researchers who have contributed to the innovation of new technologies, process optimization methods, or energy-saving techniques in metalliferous minerals development

A study on deformation of tunnels excavated in fractured rocks

La déformation due au fluage d'un massif rocheux autour d'un tunnel a été rencontrée fréquemment. Ce phénomène est évident où il y a des tunnels creusés dans la roche tendre, des masses rocheuses faible et fortement cisaillées, ou des massifs rocheux soumis à des contraintes in-situ élevées. La déformation due au fluage se produit fréquemment au moment d’excavation des tunnels longs où il y a des failles et des zones fracturées et cisaillées. Ce phénomène peut causer différents dommages sur des systèmes de soutènement en raison de la déformation excessive et des effondrements. La déformation excessive impose une ré-excavation de la section du tunnel, qui monte le coût supplémentaire, la durée de la réalisation du projet et le risque de la sécurité sur le projet. En plus, comme la stabilité de terrain est dans un état critique durant la ré-excavation, une petite négligence peut conduire à une grande caverne. Bien que la déformation de fluage est commune dans un massif rocheux à une faible résistance dans un tunnel très profond, mais ce phénomène a été observé dans des tunnels peu profonds. Une bonne compréhension des déformations causées par une excavation souterraine requiert la connaissance de l'interaction roche-support et l'interprétation des données de terrain. Auparavant, l’objet principal de la surveillance effectuée durant la construction du tunnel était des mesures de la pression au terrain imposé sur le revêtement du tunnel. Mais aujourd’hui, les méthodes modernes de construction de tunnel se concentrent sur la surveillance des déplacements pendant et après la construction. Afin de déterminer des déformations dans les tunnels, Panet et Sulem ont supposé que "Le tunnel a une section transversale circulaire et le milieu est homogène et isotrope, aussi le tunnel est suffisamment profond pour considérer que la distribution des contraintes est homogène". Mais dans le cas quasi réel, la distribution de la contrainte autour du tunnel est hétérogène et anisotrope. Dans cette étude, pour la modification des équations Panet et Sulem, certaines équations sont proposées en cas de matériau hétérogène et anisotrope pour généraliser le problème. La galerie de force motrice Seymareh a été considérée comme l’étude de cas. Celle-ci est une partie du conduit d’eau dans le projet de centrale électrique du barrage Seymareh. Ce projet est situé à l'ouest de l'Iran. Les données de surveillance de la galerie de force motrice sont collectées au moment de l’excavation du tunnel, et sont comparées avec les résultats de la modélisation numérique et de la solution analytique. Cette comparaison montre que les résultats des données expérimentales obtenues par la surveillance sont très proches des résultats de la solution analytique, mais il y a une différence entre les deux et la modélisation numérique. Il était prévisible, car l’effet d’autres activités comme l’excavation des tunnels verticaux n’est pas prise en compte dans l’analyse numérique et aussi dans la solution analytique. Il est évident que les autres activités comme l’excavation des tunnels verticaux et l'excavation du tunnel principal vers deux directions opposées, peuvent affecter sur les résultats de la surveillance. D'autre part, les données initiales utilisées dans l'analyse numérique et la solution analytique ne sont pas tout à fait exactes, car elles sont obtenues en tant que représentatives du massif rocheux de la région, mais pas pour une section particulière. Toutefois, le but de cette étude est le développement d'une solution analytique de la déformation dans les tunnels sur les conditions générales et la poursuite de cette étude pourra être plus développée.The creep deformation of a rock mass around a tunnel has been encountered frequently. It is particularly common in tunnels excavated in soft rock, heavily sheared weak rock masses or rock masses subjected to high in-situ stresses. Creep deformation in fault and shear fractured zones are one of the frequently encountered difficulties in long tunnel construction, which tend to cause failure of supporting systems due to excessive deformation and cavern. Excessive deformation would necessitate re-mining of the tunnel cross section, thus imposing impacts such as extra cost, extended time schedule and safety risk on the project. Furthermore, as the ground stability is in critical condition during re-mining, the slightest negligence would lead to major cavern. Although creep deformation is common to extremely poor rock mass under high overburden in a tunnel alignment, but however this phenomenon is not limited to tunnels with high overburden. A good understanding of the deformations caused by an underground excavation requires simultaneously knowledge of the rock-support interaction and interpretation of field data. Formerly, the main purpose of the monitoring carried out during tunnel construction was to measure the ground pressures acting on the tunnel lining. Modern tunneling practice emphasizes the monitoring of the displacements occurring during and after the construction. Panet and Sulem for determining of deformations in tunnels have assumed that "The tunnel has a circular cross section and around the tunnel, the rock is homogeneous and isotropic and also the tunnel is deep enough to consider that the stress distribution is homogenous". But in almost real cases, the stresses distribution around the tunnel is not homogeneous and isotropic. In this study, for modification of the Panet and Sulem equations, some equations are proposed in case of nonhomogeneous and anisotropic for generalizing of the problem. Seymareh power tunnel which is considered as a case study is a part of the powerhouse waterways system of the Seymareh dam and hydroelectric power plant project. The project is located in west of Iran. The monitoring data of power tunnel which are collected during excavation of tunnel is compared with the results of numerical modelling and analytical solution results as well as. The results obtained from comparison show although the field data, which are collected through the monitoring, are very close to the analytical solution results (approximately), but there is a significant difference between both of them and numerical modelling results. It was predictable; because the influence of the other activities such as excavation of shaft and surge tank in the numerical analysis and also analytical solution are not considered. It is obvious that other activities such as excavation of shaft and surge tank and also excavation of mean tunnel from other direction which were under operation at the same time can effect on the results of monitoring. On the other hand, the initial data which are used in numerical analysis and analytical solution are not quite accurate; because they are extracted as a representative of the rock mass of region, not for a particular section. However the goal of this study is development of analytical solution of deformation in tunnels on general conditions and pursuit of the study could be leaded to more development in this field

The reliability of rock mass classification systems as underground excavation support design tools

This thesis examines the reliability of rock mass classification systems available for underground excavation support design. These methods are sometimes preferred to rational methods of support design particularly if detailed information required for the latter mentioned methods is lacking. The classification approach requires no analysis of any specific failure mechanisms or the forces required to stabilise unstable rocks, yet, the support measures thus designed are considered to deal with all possible failure mechanisms in a rock mass.Amongst the several rock mass classification methods developed for application in underground excavation engineering, two have stood out. These are known as rock mass rating (RMR) and tunnelling quality index (Q), introduced by Bieniawski (1973) and Barton et al. (1974), respectively. Over the years, the two methods have been revised and updated so as to improve their reliability as support design tools, yet the two methods are know to have limitations and their reliability has long been a subject of considerable debate. Nevertheless, attempts to assess their reliability in a systematic manner have been limited. Further, some practitioners in the field of rock engineering continue to use these methods as the sole methods of support design for underground rock excavations. The objective of thesis, therefore, is to contribute to a better understanding of the reliability of the two classification methods.This study considered that the reliability of the RMR and Q methods can be assessed by comparing their support predictions with those derived by other applicable methods and also with the actual support installed. Such an assessment can best be carried out during excavation of an underground opening because representative data can be collected by direct observation of the as-excavated ground conditions and monitoring the performance of the support installed. In this context, the geotechnical data obtained during the construction of several case tunnels were reviewed and the two classification methods were applied. The effectiveness of their support predictions was then evaluated against the potential failures that can be predicted by some of the applicable rational methods. Since the rock masses intersected in the case tunnels are jointed, mostly the structurally controlled failure modes were analysed. The support measures predicted by the two methods were compared with each other and with the actual support installed in the case tunnels. Further, the RMR and Q vales assigned to the case tunnels were correlated to observe any relationship between the two.The study showed that the RMR and Q predicted support measures are not always compatible. In some circumstances, the two methods can either overestimate or under estimate support requirements

Transbasin water transfers

Presented at the 2001 USCID water management conference, Transbasin water transfers on June 27-30, 2001 in Denver, Colorado.It too often is the case that transbasin water transfer projects, worldwide, could be beneficial to an entire region and are well engineered and yet will never be constructed. This paper reviews social, political, financial, economic, and environmental factors that were dealt with in an effective manner by strong project advocates to realize the construction of the Laja Diguillin Irrigation Project. The Project is located in Region VIII of southern Chile. It stretches across nearly 100 kilometers of stream-dissected terrain to the south of the City of Chillan. The newly built primary transmission canal was designed to convey 1400 cusecs (40 cumecs) of diverted river flow from the Laja River, across six intermediate streams, to discharge some 28 miles (45 kilometers) distant into a pool created by a rubber dam on the Diguillin River. From this pool at the town of Bulnes the water is to be further diverted, along with flow of the Diguillin River, into a system of large primary irrigation canals. This transbasin diversion project was designed to provide economic uplift to the farmers of the region who had not participated in the near countrywide economic boom of the 199Os. Thus the Chilean Government chose to plan, design, and build the project while still maintaining the principle that the private sector should own, operate, and maintain irrigation projects. Additionally, the Directorate of Irrigation of the Ministry of Public Works was empowered, after some 50 years without designing a major irrigation project, to carry out with government financing the Laja Diguillin Project. The coalescence of factors that the Ministry recognized and made effective accommodations for may be grouped into four categories. They were: 1) advocacy, which was strongly provided by Directorate personnel; 2) social, characterized by the challenge to integrate newly enfranchised irrigators with existing water users and their organizations; 3) government, which as a dynamic emergent democracy with an established bureaucracy of skilled technocrats and economists was flexible and able to adopt new or innovative approaches; and 4) competing interests for water and land, embodied in three groups who actively opposed the project for environmental and commercial reasons

Transbasin water transfers

Presented at the 2001 USCID water management conference, Transbasin water transfers on June 27-30, 2001 in Denver, Colorado.Includes bibliographical references.As the headwaters for seven major rivers, water resources in Colorado have been diverted for use for over 150 years. Transbasin diversions have been developed to move water from one river basin to another, including transmountain diversions, which move water over the continental divide. Transmountain diversions have historically been developed to provide water for irrigated agriculture and municipal purposes. This paper briefly discusses the development of each of Colorado's 30 transmountain diversions between the Colorado, South Platte, Arkansas and Rio Grande river basins, and provides a summary of diversions for recent years

Transbasin water transfers

Presented at the 2001 USCID water management conference, Transbasin water transfers on June 27-30, 2001 in Denver, Colorado.To view the abstract, please see the full text of the document

HB12-1278 Study of the South Platte River alluvial aquifer

December 2013.Includes bibliographical references

Transbasin water transfers

Presented at the 2001 USCID water management conference, Transbasin water transfers on June 27-30, 2001 in Denver, Colorado.Includes bibliographical references.Manusmara River Basin, a sub-basin of the Bagmati River Basin, lies in the Terai of Nepal. It lies in the sub-tropical climatic zone. The topography is almost flat with a very gentle slope towards the south. Up to the mid 1960s, a large portion was covered by dense, Sal forest. At present, only 6% of the area is occupied by forest. Over the last few decades, consumption of water especially for agriculture has increased tremendously. This paper draws out the history of agricultural development in the basin and its interface with the efforts made by the fanners to use the basin water resources. Water accounting has revealed that Manusmara is an "open basin" and it still offers ample scope for transbasin transfers and further harnessing of the available water. Even during the driest year, only 46% of the available water resources is depleted. This leaves more than half of the basin's yield for undeclared uses. The basin is at the initial stage of development. On the basis of the water account and an institutional analysis, the paper offers some suggestions for integrated development of the basin