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The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
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ABSTRACT Potash and salt deposit development is always associated with the risk of inrushes of fresh waters into stopes and mine flooding. This article considers experimental and theoretical approaches to mining safety and mine protection from flooding that are based on an informative interpretation using mathematical modelling results of instrumental and geophysical studies regarding mechanical properties and stress-strain state of undermined rock mass. A comprehensive implementation of these methods provides adequate mathematical modelling results and allows increased validity of predictive estimates related to stability of structural elements and integrity of water-blocking strata when it comes to the room-and-pillar method. 1 INTRODUCTION An increase in demand for potash-magnesium ores that are used in many industries requires a considerable increase in potash salt extraction. This is achieved by both an increase in operating mine capacity and the construction of new enterprises (the development of the Ust-Yaivinsky, Polovodovsky, Talitsky sites at the Upper Kama potash deposit (the Upper Kama potash-magnesium salt deposit, UKPMSD), mines in Belarus, Uzbekistan and Tajikistan). The developed sites are characterized by difficult mining-geological and hydrogeological conditions (the presence of water-bearing and unstable rocks), which increases the risk of technogenic accidents. The main risk associated with the UKPMSD mines is an inrush of surface waters into stopes. The overlying rocks separating the water-bearing horizons from the mined-out space must preserve their continuity throughout the whole service life of a mine, thereby performing functions of a waterproof pillar — of the water-blocking strata (WBS). This is achieved by the use of the room-and-pillar method with continuous ore excavation and maintenance of all the overlying strata on the chain pillars that must preserve their bearing capacity throughout the whole service life of a mine . The exploitation of the deposit at the mines of PJSC Uralkali has resulted in large mined-out spaces of tens of square kilometers that are still increasing. As long as mining operations are developed, the risk of discontinuity of the water-blocking strata and consequently that of mine flooding is constantly increasing.
Barla, Giovanni (Politecnico Di Torino) | Mehinrad, Abolfazl (Samanian Technical & Engineering Co.) | Gheshmipour, Ali (Samanian Technical & Engineering Co.) | Binazadeh, Niloofar (Samanian Technical & Engineering Co.) | Ebrahimi, Idin (Samanian Technical & Engineering Co.) | Khoshrang, Gholamreza (Tunnel Pars Co.)
Abstract Rogun dam is a 335 m high clay core rockfill dam, which will be constructed on Vakhsh River in Tajikistan. Originally, two diversion tunnels with similar geometry were designed for discharging the seasonal floods, up to 3290 m/s. River diversion was carried out in November 1987 and a 45 m high rockfill cofferdam was constructed. However, because of two collapses in the diversion tunnels, the cofferdam was overtopped in May 1993. Reconstruction of these tunnels started in 2009 and the collapsed areas were repaired. Nowadays, the design of complementary rehabilitation including new concrete lining for those parts of the tunnels, which will be used as tailrace tunnels are underway. The present paper describes the present conditions of diversion tunnels No. 1 & 2 and explains the procedure used for stress analyses of tailrace tunnel No. 1 without and with the new lining, which, has been designed to guarantee its long-term performance. 1 Introduction Rogun dam is a rockfill dam with clay core, which will be constructed on Vakhsh River in the Republic of Tajikistan. In its final stage, with crest elevation of 1300 masl, it will be 335 m high and therefore, the highest dam in the world under construction. The powerhouse is of underground type and with its 6 turbines it will have total capacity of 3200 MW. Originally, two diversion tunnels with similar geometrical characteristics were designed for discharging the seasonal floods during construction period of the project, up to 3290 m/s. Each tunnel is of D shape section with various sizes along its length, starting with 11(w)x11(h) m in pressurized section which reaches to a gate chamber and after the radial gates, there is a sloping part with 14(w)x11.9(h) m section. Finally, cross section of the tunnel converts to 14(w)x17(h) m which will be used as tailrace tunnel during operation period. Each tunnel is almost 1410 m long and while its inlet portal and almost 950 m of its length is located at left bank, after crossing the river, its outlet portal is situated in right bank. The total length of each tunnel is about 1410 m. Construction of the project started in 1980's during which excavation and construction of the two diversion tunnels were carried out. River diversion was carried out in November 1987 followed by construction of a 45 m high rockfill cofferdam. However, because of two main collapses in the diversion tunnels the cofferdam was overtopped in May 1993. Reconstruction of these tunnels started in 2009 and the collapsed areas were repaired. Nowadays, the design studies of complementary rehabilitation works including new concrete lining for those parts of the tunnels, which will be used as tailrace tunnels are underway. This paper describes the present conditions of diversion tunnels No. 1 & 2 and explains the procedure used for stress analyses of tailrace tunnel No. 1 under the highest overburden without and with the new lining, which, has been designed to guarantee its long-term performance.
ABSTRACT The underground works of the Rogun dam project in Tadjikistan comprise: machine hall 20m wide, 70m high and 220m long and transformer hall 18m wide, 37m high and 182m long. To assess deformation properties of the rock masses composed of sandstone and aleurolite which surround the underground excavations, a set of methods was applied including dilatometers, seismic and ultrasonic measurements, determination of moduli of deformations by the Hoek and Brown method applying the Bieniawski rock quality classification as well as defining the values of moduli from the measured convergence of the machine hall walls by solving a number of 2-D and 3-D problems to estimate the stress-strain state of the "host rock-underground excavation" system at different phases of construction. Described herein below are the technique and results of conducted investigations as well as comparative evaluation of the moduli of deformation obtained by different methods. 1 INTRODUCTION Deformability of the rock masses serving as the foundation for the surface structures and as host medium for the underground works is one of the major factors governing behavior and safety of the entire "structure–foundation" system. The criteria of rock deformability – the moduli of elasticity and deformability – are the major parameters used to analyze the rock masses on the computational models (Technical Report 2005, 2006). For the real rock masses featuring their structural heterogeneity and anisotropy as well as certain primary stressed state, estimation of their deformation properties is a complex and critical engineering task. Solution of this problem considering the size of the bearing area and the type of surface structures or volumes of underground excavations is aggravated by the presence of the scale effect i.e. dependence of magnitudes of the moduli of elasticity and deformation on the applied scale of investigations (Savich & Kujundzi'c, 1985). Today's engineering practice uses various direct and indirect methods of determining the moduli of elasticity and deformation, as well as Poisson's ratio for the rock masses in their pristine state including the rating approaches to assess the above parameters by a set of geological features of the rock masses in question (Bieniawski 1979, Bieniawski 1989, Barton et al. 1974). The final results of these determinations can materially vary and therefore there arises necessity of selecting those data which most correspond to the specified design computational model and the real behavior of the "structure–foundation" system. Such a problem arose in construction of a large underground machine hall at the Rogun dam project on the Vakhsh river in Tajikistan. 2 CHARACTERISTIC OF PROJECT AND UNDERGROUNDWORKS LOCATION The underground works of the Rogun dam project comprise:–machine hall 20m wide, 70m high and 220m long; –transformer hall 18m wide, 37m high and 182m long located at a distance of 63,5m (within center lines) on downstream from the machine hall, and –various underground excavations. Excavation of the machine hall cavern began in 1986 and excavation was carried to the full width of the cavern in 6–11m deep benches. s.
Bronshteyn, V.I. (Centre of Geodynamic Research Service, JSC Centre of Engineering UESR) | Zhukov, V.N. (Rus-Engineering (Russian Aluminum)) | Yufin, S.A. (Moscow State University of Civil Engineering) | Zertsalov, M.G. (Moscow State University of Civil Engineering) | Ustinov, D.V. (Moscow State University of Civil Engineering)
ABSTRACT The construction of the underground Rogun hydropower station in Tajikistan was interrupted due to the termination of central financing with the disintegration of the USSR in the beginning of the 1990s. Recent plans to update and complete the project require careful evaluation of the trends in rock mass behavior in the vicinity of the large caverns that make up the machine and transformer halls and the gate chamber, which is undercut by numerous penstocks, draft tubes, drainage galleries and bus ducts. The most challenging task is to account for the rock mass/cavern behavior and interaction during the almost 15 years of stalled excavation activity and to formulate prognoses for the period during which the construction will be completed. This evaluation is being carried out numerically and backed up with sporadic in situ measurement data. 1 INTRODUCTION The Rogun hydropower station was designed as the next development stage of the RiverVakhsh inTajikistan to be constructed after completion of the 2700MW Nurek project with the highest (300 m) rockfill dam in the world. The project called for six generating units of 3600MW total installed capacity in a fully underground outfit with a dam of 335 m, even higher than the Nurek dam (Yufin et al., 1999). This was to have been the largest underground hydropower station in the former USSR, sixth, if completed recently, hydropower station on the River Vakhsh. The complex of underground structures at the Rogun site, with a total length of some 40 km and excavation volume of 3×106 m3, is located in rock mass consisting of sandstones and aleurolites. Two major caverns for the machine hall (MH) and the transformer hall (TH) are situated at a depth of 350–400m from the ground surface and are 21×70×220m3 (MH) and 19×37×182m3 (TH) in size. The distance between the axes of these caverns is 63m and the pillar contains drainage galleries and bus ducts. At an angle to these two caverns there is a shorter penstock assembly/gate chamber (AC) with a span of 12 m, height 37m and length 50 m. All three caverns are situated in a single tectonic block and separated by active faults from the surrounding rock mass. Sandstones and aleurolites in this region are rather strong rocks with uniaxial compressive strength of 100–120MPa and 60–80MPa respectively. 2 PROJECT HISTORY The excavation of the machine hall started in September 1986 and was carried out in benches 6–11m high along the total width of the cavern. By the beginning of 1990, theMHcavern had been excavated to a depth of 36m and the TH cavern to a depth of 16 m. 3 RECENT NUMERICAL ANALYSES To evaluate the feasibility of completing cavern construction, a series of numerical analyses were performed in 2005–2006 under contract to the RUSAL Company.
Ezersky, M.G. (Hydroproject Association) | Ilyin, M.M. (Hydroproject Association) | Yakovlev, B.P. (Hydroproject Association) | Kolichko, A.V. (Central Asia Department of 'Hydroproject&apos)
ABSTRACT: Unloading of high. stress rock mass made from sandstones and aleurolites in course of construction of a machine hall and transportation, tunnel at the Rogun hydropower station (HPS) has been studied. Results of operation ultrasonic observations have been treated. Sup-" port type, strength state and geological factors are considered. Results have been interpreted in the framework of viscous-plastic model of mass and lining interaction. RESUME: L"objet de l"etude est le developpement dans le temps du dechargement d"un massif rocheux à contraintes elevees constitue de grès et de pelites au cours de la construction de la salle des machines et de la galerie de transport de la centrale hydroelectrique Rogounskaya. On passe en revue les resultats des explorations, ultra-sonores de regime representant. On examine l"influence du type de soutènement, de l"etat de contrainte, des facteurs geologiques sur les caracteristiques du dechargement. Les resultats sont interprete dans le cadre du modèle viscoplastique de l"interaction du massif et1du coffrage. ZUSAMMENFASSUNG: Untersucht wird die zeitliche Entlastung des hochgespannten Felsmassivs, zu- sammengesetzt aus Sand- und Schluffstein, bei der Errichtung des Maschinensaals und des Transporttunnels fur das Rogun-Wasserkraftwerk. Ausgewertet werden die Ergebnisse der Ultraschall- Operationsbeobachtungen. Untersucht wird die Beeinflussung der Entlastungsparameter durch den Typ der Stutzen, den Spannungszustand und die geologischen Faktoren. Die Ergebnisse werden im Rahmen eines zah-plastischen Modells der Wechselwirkung von Massiv und Umhullung interpretiert. 1 INTRODUCTION A problem of unloading rock masses including complex underground constructions is given a great attention in the modern soil mechanics because this process, namely, in a large extent conditions of their design and assembly, parameters and support type, technology of its mounting and in the last range construction stability (Field measurements … 1979). But the most important this problem becomes in rock masses with relatively high levels of natural stresses and pronounced rheological properties. An example is a mass of sandstones and aleurolites where an underground complex of the Rogun HPS constructed on the Vakhsh river, Tajikistan (USSR), is located. The underground complex being built at the depth level of 420 m from ground surface has the following components: a machine hall (MH) 20.8x67x200 m in size, a transformer hall (TH) 19x36x182 m in size situated at a distance 40 m from MH at the side of the downstream as well as various purpose tunnels more than 80 m in section (Fig. 1, a). The machine hall is located in a single tectonic block bordered with active fractures, No 1 (Ionakhshski) and No 35 which stipulated the only possible, orientation of MN on the scheme (Iliushin & Kolichko 1981). Bedrock near MH and adjacent workings are structured from la- minated sandstones and aleurolited of the low the north-east direction. Sandstones and aleurolites are strong rock masses having 100–120 and 60–80 MPa one axis resistance to compression in a specimen, and 7.5–11.0 and 2.0–5.0 MPa tensile strength accordingly. A distinctive feature of the mass is its natural high compressive strength of tectonic origination. Measures made in the field boreholes with unloading, ultrasonic and compensational (pres-siometric).
Kolichko, A.V. (Hydroproject Institute (Middle Asia Branch)) | Parabouchev, I.A. (Hydroproject Institute, Moscow) | Stepanov, V.J. (Rock Mechanics & Physics Institute, Kirgiz Academy of Sciences)
SUMMARY: The problem of siting the underground powerhouses in the environment which is most favourable ''for Construction and operation of the powerhouse necessitates maintaining stability of large-size caverns. Excavation of such caverns in the mountain regions which are still tectonically active and are characterized by high seismisity sets some special requirements for the minuteness of investigations in elements of engineering geology and their Consideration in locating of the underground works, configuration and orientation of the caverns. In the USSR, like detailed investigations are carried out for all proposed hydrodevelopments with underground powerhouses and deep-set water-conveying tunnel systems. The paper deals with some results of investigations of the above factors and their accounting in design of the Rogun project on the Vakhsh River whose power house cavern is proposed to be 28 m wide, 68 m high and 200 m long. ZUSAMMENFASSUNG: Das Problem der bau-und betriebsguenstigen Lage von Maschinenkavernen fuer Wasserkraftwerke steht im Zusammenhang mit der dauerhaften Standsicherheit von Hohlraumen grosser Abmessungen. Der Bau derartiger Hohlraume in Gebirgsgebieten, die durch rezente tektonische Aktivitaten und starke Erdbebenwirkung gekennzeichnet sind, erfordert die umfassende Erfor- Schung von mehreren ingenieur-geologischen Einfluessen und deren Beruecksichtigung bei der Auswahl des Standortes, der Querschnittsform und Raumstellung dieser unterirdischen Hohlraume. In der USSR werden derartige Untersuchungen fuer all zu projektierenden Wasserkraftanlagen mit Maschinenkavernen und tiefliegenden Umleitungsstollen durchgefuehrt. 1m Bericht werden einige Untersuchungsergebnisse und deren Ausnutzung fuer die Projektierung der Wasserkraftanlage Rogun am Wachsch mit der Maschinenkaverne von 28 × 68 × 200 m beschrieben. RESUME: L''implantation des centrales hydroelectriques souterraines dans les conditions les plus favorables pour leur construction et exploitation exige la stabilite de longue duree des cavernes de grandes dimensions. La creation de telles cavernes dans les regions montagneuses, qui se caracterisent par une activite tectonique recente et par une sismicite elevee, impose des exigences particulieres a l''etude detaillee de divers facteurs geologiques et à leur consideration pendant le choix des emplacements des ouvrages souterrains, de la forme de leur section et de leur orientation dans l''espace. En URSS, les etudes de ce genre s''etfectuent pour tous les amenagements hydrauliques projetes avec les centrales en caverne ou les derivations en souterrain de grande profondeur. Dans le rapport sont examines certains resultats d''etude des facteurs indiques et leur consideration pendant l''elaboration du prQjet de l''amenagement hydraulique de Rogoune sur le Vakch dont la caverne puur la salle des machines a une largeur de 28m, une hauteur de 68 met, une longueur de 200m. Construction of underground structures having large sections and which are to be constructed in mountainous regions characterized with great seismicity, modern tectonic movements at fructures and with availability of great natural stresses, has on the one hand to meet the particular engineering and geological requirements when substantiating the design, and on the other hand to take into account all peculiarities and abilities of the rock mass when designing. In this sense the Rogoun hydroelectric station is extremely demonstrative; the construction of this station has been started some years ago on the Vakhsh river in Tajikistan, USSR. The project consists of the following structures: a rock and earth dam 320 m high, a water intake structure, inlet tunnels, an underground power house which is located in upstream at a depth of 420m from the surface of the ground, and the outlet tunnels. The power house has a two-room layout: the machine room of the power house and the premises for transformers are located in parallels and have the following size: they are 28 m wide, 68 m hd.gh, and 200 m long. From geological point of view the Rogoun project area is located within the zone of a joint of the two largest structural-facial regions of Middle Asia - south-west Tien Shan and east Pamirs - and it is characterized with highly active modern tectonic movements.