Abstract Drill and blast is the excavation method adopted to remove overburden material at the open pit coal mine of PT Buma Job Site Lati. Recently, the company applied deep hole drilling for blasting with double rods to reach the depth of 10–18 m. The main explosive was an emulsion explosive with target explosive consumption of 0.23 kg/m 3 . The blast hole was not fully charged but vertically decoupled using air decks at the middle and bottom of each blasting hole. Blasted rocks were then measured by digital photograph, and the size of P80 was found to range from 200 to 800 mm. The evaluation results indicate there is close relationship between the explosive consumption and the fragment size as well as the digging time. The air deck technique adopted in this study has been giving good results in terms of fragmentation size and explosive consumption. 1. Introduction In mining operations, drilling and blasting with a deep hole is a preferred method to reduce lost production time caused by the delays in blasting, to increase blasting inventory, and to minimize the number of drill pads so the drilling deviation can be minimized as well. Recently, PT BUMA Job Site Lati (called BUMA from now on) applied drilling for blasting operations with double rods to reach the depth of 10–18 m. Consequently, explosive consumption was high in the lower part of the blast hole, then an air deck was used to distribute the explosive along the blast hole. Another benefit of the air deck was that it cut the waiting time of the on-site sensitized explosive expansion to accommodate gassing. In this study, the performance of blasting operation using the air deck is evaluated in terms of fragmentation. This study aims to check the effectiveness of using an air deck with the productivity target at the particular mine and to develop a blasting-fragmentation model that can be used to predict the size of the fragmented rock. 2. Literature Review The air deck method is well-known in blasting operations to improve the quality of the blasting results. In the early 1940s, Russian scientists first came up with the idea of using an air gap between explosive columns. This method reduced explosive consumption in blasting activity. Melnikov et al. (1979) mentioned that an air deck can act as an energy accumulator. Marchenko (1982) found that pressure in an air deck would expand micro fractures that were previously generated by the main shock wave during blasting. Pompanna and Chikkareddy (1993) concluded that the presence of an air gap in the blast hole can reduce ground vibration and back break at the Kudrremukh iron mines. Jhanwar et al. (1996) revealed that the mechanism of air deck can reduce 25–30% of explosive consumption. Chiapppeta (2004) conducted experiments in the field and found that the air deck technique could remove the sub-drill which in turn reduced the explosive consumption by 16–25%, decreased vibration due to blasting by 33%, and improved fragmentation by 25%. Utilization of an air deck will increase the fracture network due to the secondary shock waves formed as the result of wave reflection in the air gap. The fracture degree increases as a result of secondary shock waves as the duration of the shock wave effect on the rock mass around the blast hole becomes longer. The pressure reflections from the upper and lower explosive columns will collide in the middle of the air deck and is expected to interact with the surrounding rock mass to form additional radial fractures (Moxon et al., 1993; Zhang, 2016; see Fig.1). Air deck methods have been used in some open pit mines to reduce the consumption of explosive and to improve fragmentation (Chiapetta, 2004).

Abstract MOIL Limited is Schedule - A, Miniratna Category -I, Central Public Sector Enterprise (CPSE) under the administrative control of the Ministry of Steel, Government of India. At present, MOIL operates 10 mines in central India located in the state of Maharashtra and Madhya Pradesh. Expecting 3, rest of the mines is worked through underground methods at shallow 153 m to moderate depth 353 m below the surface. MOIL is producing annually more than 1.2 million tonnes of various grades of manganese ore. All the underground mines are using horizontal cut and fill (HCF) method of stoping or its variant with back filling by hydraulic sand stowing with roof bolt and cable bolt as a pre mining support system. This paper discusses impact of discontinuities on design of mechanized over hand cut and fill method of stoping for manganese ore body of Ukwa mine. The mine has the manganese ore body at an average thickness of 5 m and is highly jointed containing three sets of orthogonal joints. It is dipping 30° – 45° towards N32°W and the ore body has strike length 5000 m. The orientation of discontinuities was the primary factor influencing stability of excavation in the ore body. Kinematics analysis was used for evaluating potential modes of failure due to unfavorably oriented discontinuities. From the analysis it is found that pre mining support of roof bolt and long bolt to be introduced for supporting the entries to the stope and also for reinforcing the stope back during extraction of the slices. The extraction of the crown pillar should be under taken immediately after the completion of the stoping. Just after the filling with sand stowing of the stope, the SDL has to be run. In subsequent runs, the sand gets compacted and its bearing capacity increases. Taking these factors into consideration, a mechanized cut and fill method along with reinforcement plans of the stope has been designed for extraction the ore body up to 5 m thick and 35°–45° inclined. 1. Introduction The Ukwa Mine of MOIL Limited is being worked since 1903. The total lease hold area of the mine is 322.608 Ha, this includes three (3) leases in Ukwa, Lugma, Gudma and Samnapur villages in Tahsil Paraswada, Distt. Balaghat of Madhya Pradesh. Composite Lease Plan of 3 Leases of Ukwa Mine with forest area is shown in figure 1.

Abstract Bedded coal and iron ore deposits in Australia are usually hosted in complexly jointed, faulted or folded, highly anisotropic rock masses. In coal, these often comprise moderately strong siltstones and sandstones with weak coal seams, siltstones and shales. For iron ore, these comprise strong banded iron formations discretely interbedded with very weak shales. Slope failure mechanisms typically involve sliding along bedding (anisotropy) planes combined with joints or faults acting as release planes or forming step-path failure mechanisms. Slope stability modelling techniques have evolved over the years and increased in complexity with continuous improvements in computing capability and available software. Less than 20 years ago, basic kinematic analysis was the primary means of designing large rock slopes. In the 2000s, the use of two-dimensional limit equilibrium analysis and numerical modelling rapidly increased with faster computing. As we approach the 2020s, three-dimensional limit equilibrium and finite element analysis software are readily available and offer a range of options to model the behavior of complex, anisotropic rock masses. The results obtained by these different modelling approaches, for example, isotropic vs. anisotropic, or 2D vs. 3D can vary significantly depending on the geological conditions. This paper presents case studies from both open pit iron ore and coal mines that compare the factor of safety (FoS) obtained from 2D and 3D limit equilibrium modelling approaches. The case studies clearly show the limitations of 2D modelling when the rock mass being excavated is highly anisotropic in nature and when large-scale geological structures are present whose geometry cannot be adequately represented in plane strain. Results further indicate that modelling solely in 2D can lead to either the over-estimation or under-estimation of FoS, by failing to locate the section of slope with the lowest FoS or failing to adequately model the anisotropic conditions under which failure is likely to occur. The tools are now readily available to facilitate 3D modelling techniques alongside existing 2D techniques to complete a comprehensive review of slope stability. This will allow both the optimization of slope designs to be completed, and increase design reliability by identifying the sections of slope more susceptible to failure in true 3D space. 1. Introduction In 2014–15, income from sales and services from coal and iron ore mines in Australia was approximately $115 Billion (AUD), which accounted for approximately 80% of total mining and quarrying sector (ABS, 2016). The Pilbara Region of Western Australia hosts the majority of economically extractable iron ore deposits in Australia. Hundreds of open cut mines are operated by major mining companies near the townships of Newman, Paraburdoo and Tom Price with single operations often having access to several individual pits in similar ground conditions. Due to the broad regional expanse of the operations, particularly in the iron ore sector, a very high extraction rate is achieved despite vertical development rates remaining relatively low (typically one to three benches or 10m to 30m per year in a single iron ore pit). Final pit depths or total rock slope heights range from less than 100m to 350m. The Hunter Valley Region of New South Wales and the Bowen Basin Region in Queensland host the main coal deposits used for energy and steel manufacturing. Mining typically begins with an initial excavation, called a box cut, and then progresses down dip in a series of strips, with the coal closest to the surface extracted first. Pit geometry is dictated by equipment capabilities, the location of economic coal seams, and geotechnical constraints to achieve an acceptable design. Individual bench heights typically do not exceed 60m and overall excavated slope heights rarely exceed 150m.

Abstract Monitoring deformation due to volcanic activity is important for understanding volcanic behavior and for predicting eruptions. The Global Navigation Satellite System (GNSS) is sometimes used for such purposes. However, the system requires the installation of sensors at the site, and the installation and maintenance of these sensors are usually difficult and dangerous when volcanoes in the area are very active. On the other hand, Deferential Interferometry Synthetic Aperture Radar (DInSAR) can be used to measure the surface deformation of volcanoes without the installation of any devices on the ground. Moreover, the time-series DInSAR analysis has the potential to reveal the deformation behavior of volcanoes at the pre- and post-eruption stages. However, the DInSAR results can be greatly affected by the temporal variation in the refractivity in the tropospheric layer, especially when there are large differences in height in the target area of the measurements. Although it is a fundamental issue of DInSAR, it is still difficult and there are only a few methods for removing the errors caused by the tropospheric delays of radar pulse waves. This paper discusses this issue and proposes two simple methods for improving the measurement accuracy. The proposed methods were applied to Sakurajima Volcano in Japan. Ground surface deformation was observed for three years, from November 2014 to August 2017, by a time-series DInSAR analysis using Sentinel-1 data (operated by the European Space Agency). In this way, the effect of the tropospheric delays was successfully reduced. 1. Introduction As a country that is located in the "ring of fire", Japan has dozens of the active volcanoes. A volcano can be disastrous when it erupts, especially one that lies near a city. Therefore, the monitoring of the volcano's behavior is very important for safety and risk management. The activities of a volcano usually lead to ground surface deformation. Thus, a volcano's behavior can be monitored through the observation of its surface deformation. Monitoring of the ground surface deformation can be conducted using a traditional measurement method, i.e., leveling or modern technologies such as GPS. Using the proper GPS method (i.e., the method developed by Shimizu et al., 2014) for surface displacement monitoring enables the yielding of continuous and highly accurate results. However, the method necessitates the installation of GPS sensors at the monitoring site. The installation and maintenance of the devices on the ground involve high costs and a great labor force. In addition, the installation and maintenance of the devices under tough and harsh conditions, like active volcanoes, can be dangerous.

Abstract Very often the situation is presented in which the instability causes landslides of rocky blocks in areas that get in the access path of access to the orebody, which is almost impossible to stabilize. Then there is no more way out than to allow the rockfall to occur, of course, looking for possible solutions for their containment and / or reduction, as the fragments that generally fall can reach high speeds and kinetic energy, which makes the phenomenon extremely dangerous and complex to face. Mining operations are increasingly faced with achieving the operational safety ideal of zero harm, while at the same time increasing productivity. The implementation of approved mitigation measures against rockfall in opencast mines is becoming very common, due to the fast installation and cost-effectiveness of such measures. According to the guidelines for rockfall barriers, mines can rely on the approval issued by the EOTA (European Organisation for Technical Assessment). Liability insurance is issued by the suppliers, who guarantee the function of their rockfall barrier systems. In many cases the pit design can be optimized by increasing the slope inclination or reducing the berm width. The solution at Mandai Quarry located at Mandai District in the northern part of Singapore, will be presented in this paper, as a case study. 1. Introduction 1.1 Rockfall barriers Rockfall belongs to gravitative natural hazard processes and endanger frequently human life, infra-structure and settlements. One of the last rockfall events happened some month ago at a main road from Austria to Italy at the Reschenpass causing a fatality as the car was hit (see figure 1). The rockfall event was much larger than the existing rockfall barrier capacity, thus the barrier could not stop the block and it got severely damaged. It was a small rockslide with an estimated volume of around 80 m 3 according to the analysis of the geologist experts. The specialist responsible of taking protective measures face, the following problems: Difficulties in predicting the possible areas from which the landslides originate and the possible trajectories of the fragments The dimensions of the type block, as well as the energy with which they can reach the access path or the area where they are intended to brake blocks. The influence that may be exerted by the material from which the own slope, on which the detachment occurs and which will obviously influence the speed trajectory of the rocks.

Abstract It is very important to study the mechanism of the behavior of a slope in order to assess its stability, to predict its future behavior, and to design countermeasure works. There is an unstable steep slope along a national road in Yamaguchi Prefecture, Japan, where heavy rain has sometimes caused large displacements. Local collapses have occurred in some areas of the slope. The GPS displacement monitoring system was installed in 2012 to continuously monitor the slope displacements. The groundwater level of the slope has also been monitored at a few well points. The slope is composed of mainly rhyolite and granite. The surface is covered with colluvial deposits that accumulated due to past collapses. In this paper, a numerical analysis is conducted to understand the mechanism of the slope behavior considering both the measured displacements and the groundwater height. The Universal Distinct Element Code (UDEC) is employed to better understand the mechanism of the displacement behavior brought about by heavy rain. The numerical analysis reveals that when the groundwater rises and reaches the height of a discontinuity (the boundary between the rhyolite and the granite), the water pressure in the discontinuity increases, the stress reaches the failure criteria, and the displacements increase largely. As a countermeasure, several horizontal drains were drilled toward the locations of the discontinuities, and the displacements became stable. 1. Introduction Knowledge of the mechanism of the displacement behavior of a slope is essential for assessing the stability of the slope, for predicting its future behavior, and for designing countermeasures. Monitoring the real behavior is important to investigating such a mechanism. There is an unstable steep slope along a national road in Yamaguchi Prefecture, Japan, where heavy rain has sometimes caused large displacements. Local collapses have occurred in some areas of the slope. A continuous displacement monitoring system, using the Global Positioning System (GPS), has been applied to confirm the behavior of the slope and to assess its stability (Nakashima et al., 2018).

Abstract Development of safe, effective and efficient access to the ore body is an important goal during underground mining. Until today, underground mining possesses a risk of failure even with help of complete data and modeling design, therefore, this uncertainty becomes a challenge that has to be tackled. Failure is a result of incapability of rock mass to cope with the stress, both with the ground support or self-supported rock mass. This failure will initiate tunnel collapse. The collapse that happened at Cibitung decline X/C 4 and X/C 5, Tambang Emas Cibaliung on April 2017 blocked the production access and trapped mine equipments. This decline is located in hanging wall which is classified as an unstable area. Ground consolidation with cement and urea silicate is one of the works carried out during tunnel rehabilitation, along in a cycle with steel set erection, fore poling installation, concrete pouring and shotcrete. Field observation, tunnel deformation data statistical analysis and numerical modeling were conducted to assess the effect of ground consolidation at unstable area. Statistical data analysis and finite element numerical modeling shows an improvement on rock mass quality after ground consolidation work. 1. Introduction Tunnel collapse happened at Cibitung decline X/C 4 and X/C 5 is caused by tunnel instability in that area. The instability in this hanging wall area is significantly initiated by the rock mass surrounding the excavation (Purwanto et al., 2013) based on its modeling results shown in Fig.1. Ground consolidation objective is to increase strength, to reduce deformability and to decrease permeability of rock masses (Lombardi, 1999). There are various types of materials commonly used to consolidate rock masses, such as cement-with or without additives (ashes, fillers and silica fumes), resin and silica urea. The selection of the right material and the right specific product for the defined project requirements is one key factor for successful injection, beside its equipment and correct injection method (Sika Services AG, 2015). Materials viscosity, strength and its behavior in contact with water are considered to select the material type. Equipment attainment is affected by pumping ability and accurate dosage, while methods can be arranged to meet objective.

Abstract This manuscript introduces a gas-induced accident in the west tunnel of Tsengwen Reservoir Trans-basin Diversion project (TRTD). Tunnelling sections with problematic gas emission have been investigated and paid attention during design stage, with gas detection instruments and associate hazard mitigation measures prepared. However, excavation of tunnel run into gas outburst, with methane concentration reaching 844,535 ppm revealed by Gas Chromatography-Flame Ionization Detector (GC-FID), resulting in a severe explosion at the cost of 2 workmen. Due to two other sections to be excavated have similar engineering geology conditions, the TRTD project was then reviewed and associate with a strict and comprehensive gas-related hazard mitigations design modification. Lessons learned from the gas emission and associate hazard are discussed and commented.

Abstract With the rapid growth of urbanization, the wide gap between demand and supply of power in the country has necessitated putting an increased thrust towards development of hydroelectric projects particularly in geologically complex Himalayan terrain. Tunnelling in Himalaya is undoubtedly the most challenging activity in hydro power construction. The hydropower tunnelling works in India were mostly accomplished by conventional drilling and blasting methods resulting in time and cost overruns. Now, while the focus is on faster completion of projects, need for an advanced technology more particularly in tunnelling is being felt. As a consequence, use of TBM has gained importance in hydropower tunnelling for being a more dependable alternative to drill & blast method. However, the ability of TBM to cope with varying ground conditions in Himalaya has posed a question mark in utility of this machine. The weak, jointed, sheared/fractured rock mass of Himalaya, under high stresses and potential confined aquifers, pose a major challenge to tunnelling engineers. The initial experience with TBM in Dulhasti Project (India) was not encouraging as TBM got submerged and ultimately buried which was partly attributed to unexpected ingress of water. Similarly, in Parbati-II and Tapovan Vishnugad Projects (India), excavation of HRT by TBM faced severe difficulties. However, success was achieved in excavation of inclined pressure shaft by a double shield TBM in Parbati-II Project. Presently, successful construction of 14.7km of HRT in Kishanganga Project (India) by double shield TBM has established TBM technology as a viable alternative for execution of long tunnels in Himalayas. The paper presents a brief account of the geological and geohydrological problems faced in some of the TBM driven hydropower tunnels in India, lessons learnt from them and prospects and the future challenges to be faced in TBM driven Himalayan tunnels.

Abstract Managing the preventive maintenance of slopes along national expressways is a fundamentally important issue. A rational and effective management system, including monitoring methods, is required. The West Nippon Expressway Company gives priority to potentially unstable slopes, while considering geographical and geological features. It continuously monitors deformations, such as rises in underground water levels or rainfall, for the design of countermeasures or mitigation to prevent slope failures. This paper describes a case study of monitoring the displacements of a cut slope, composed of pelitic schist, along an expressway over a period of a few years. The slope had been unstable due to localized torrential rain. A GPS slope movement monitoring system continuously monitored the slope displacements at several measurement points, and it was able to detect the initial signs and processes leading up to slope failure. When the velocity of the displacements measured by GPS exceeded the criteria for assessing stability, counterweight fill work was conducted to increase stability. The three-dimensional displacements continuously monitored by GPS provided useful data for estimating the extent of the area with large deformations caused by the rainfall. Then, cut-and-removal work at the top of the slope was designed as a permanent measure for the stabilization of the slope. At the same time, it was decided that the expressway would be temporarily closed to traffic based on the measurement results by GPS. It was proven that GPS slope movement monitoring is effective for managing the preventive maintenance of expressways.

Abstract The Global Positioning System (GPS) began to be used for displacement monitoring in the fields of Rock and Mining Engineering in the mid-1980s. Although it had the potential to measure displacements of the ground surface continuously over an extensive area, it was not applied much in practice. The reasons were uncertain accuracy, troublesome handling, and high costs at that time. In order to overcome those issues, an automatic displacement monitoring system using GPS was developed. The system can measure three-dimensional displacements automatically with mm accuracy; it is now being widely used in various rock and geotechnical engineering projects in Japan. The authors have applied the system to monitoring many slopes and have proved its validity through its practical use. This paper describes three case studies of applications of the GPS displacement monitoring system to large landsides, namely, Choja, Shimekake, and Kokugawa. 1) Choja landslide began to occur due to the hard rain caused by a typhoon in 1963 and it still continues to move. The sliding area is 200 m in width and 900 m in length with an average slope angle of 15 degrees. The geology around the sliding plane is composed of serpentinite and slate. While the displacement was 2 m a year at the beginning, it has decreased to a few cm a year due to countermeasure works. Comparing the measurement results by GPS and by inclinometers and extensometers, the validity of GPS is discussed. 2) The sliding area of Shimekake landslide is 400 m in width and 700 m in length. Since a large displacement of 15 cm occurred in one day due to a thaw in 2009, real-time displacement monitoring has been conducted using GPS. The geology of the sliding plane is composed of tuff and mudstone. 3) Kokugawa landslide was brought about by a rapid thaw in 2012. The area of 200 m in width and 500 m in length was squeezed downward 250 m within a few days. The GPS displacement monitoring system was installed in the landslide area to observe the movement; it detected a displacement of 10 cm per hour and continuously measured the area until the landslide stopped. Through these three case studies, it is proven that GPS is useful for the continuous and safe monitoring of large landslides over a long term.

Abstract Four case studies of GPS monitoring are presented for various purposes. World heritage of Borobudur in Indonesia is for conservation and to study structural stability. Two cases are observation method applied for excavation at Toyonaka and at Temma in Osaka. Another case is for forensic engineering for identifying settlement of a warehouse by nearby macadam sock yard in west Osaka. Differential GPS method was applied with accuracy of measurement of displacement in a few mm. A base GPS monitoring point was installed as the reference point nearby the monitoring sites. Sometimes, however, the reference point that was considered as the stable fixed point within the site was displaced by some reason. Geo Spatial Information Authority of Japanese Government had established Geonet System that is realtime GPS information network to public. Geonet provides some 1300 GPS points to cover all over Japan. Case studies present the use of Geonet data to the sites where the reference points were discussed with the stability and show that Genet data are useful in most cases to interpret the monitored behavior.

Abstract This paper shows five case studies of the dynamic behavior of tunnels caused by the Hyogo-ken Nanbu earthquake (M = 7.3) occurring in Kobe, Japan, in 1995. The epicenter of this earthquake was shallow and 15 km underneath the tunnels. Right after the earthquake, a field observation was carried out on the tunnels to investigate what kinds of damage the tunnels sustained. In this paper the results of the observation on the following five tunnels are summarized. Three-lane highway double tunnels were under construction by NATM when the earthquake occurred. The tunnel situated in a diluvial formation had no damage, although the ground floor of a four- story reinforced concrete building sitting on the ground surface was completely destroyed. A two-lane highway tunnel was excavated in granite by NATM. The concrete lining of the tunnel located in a fault zone, was crushed at the spring line, and the reinforcing steel bars buckled. A circular shield tunnel for a sewerage system, bored in a diluvial formation, had just been completed. The tunnel experienced almost no damage, except for small horizontal cracks appearing at the spring line, while buildings sitting on the ground surface above the tunnel were seriously damaged. A by-pass river tunnel was excavated in rock through a geological discontinuity of granite and sand/clay stones. The tunnel was cut into rounds at the discontinuity and moved about 8–10 cm in the horizontal direction. An underground subway station, constructed by the cut-and-cover method, seriously failed in such a way that the center pillars of the station completely collapsed, resulting in subsidence on the ground surface. This failure may have occurred due to high frequency vertical excitation. These case studies show that tunnels excavated by tunneling methods such as NATM and shield are generally quite strong against earthquakes in comparison to structures such as buildings sitting on the ground surface. On the other hand, the stability during earthquake excitation of tunnels constructed by the cut-and-cover method is questionable.

Abstract The authors performed some laboratory model experiments on faulting and various rock engineering structures subjected to thrust, normal and strike-slip faulting movements under dynamic condition. The authors also compiled many case histories on the damage state and failure of various rock engineering structures caused by the earthquakes. The authors present the outcomes of laboratory model experiments and compiled case history data in this article and their implications are discussed with the consideration of practical situations. The adverse effects of fault breaks on rock engineering structures can be minimised to a negligible level in view of findings presented in this study.

ABSTRACT This paper focuses on the design case of 00 Tunnel, the first ever long deep tunnel having a y-junction to be constructed in Korea, about ensuring pillar safety and evaluating appropriate ventilation system. The pillar safety is evaluated by using strength-stress ratio and Mohr-Coulomb criteria. The tension force applied by tension bolts, acting as confining stress to the pillar, increases the strength of the pillar. With the pillar width of 2m, the expected increase in safety factor is 3~15% depending on tension force. As for excavation methods, smooth blasting is used for first excavation tunnel, and non-vibration excavation is used for second excavation tunnel to minimize damage of bedrock near the pillar. A model test to evaluate the ventilation system near the y-junction was conducted. With the installation of partition wall and jet fans in the junction area, it is possible to control the flow rate ratio between the ramp tunnel and the main ramp tunnel in response to variable situations of the tunnel.

ABSTRACT There are so many technical aspects related to tunneling in weak rock because of encountering rock mechanics problem such as high strain rate, squeezing,…together with practical problems. Tunneling in this condition requires the considerable use of a combination of support systems such as shotcrete, rock bolts, wire mesh and steel sets to stabilize the tunnel. Using of top heading and benching down excavation method in large cross section tunnels, stability of support systems installed in heading section while executing benching step is one of important issue which has to be taken to account. In this study, several methods for benching in weak ground condition have been studied and the method used in long penstock tunnels of Roudbar dam waterway as a case study has been explained. The method including excavation of two side wall of benching section beneath crown support system and filling excavated area with reinforced concrete piles has been investigated through numerical models using FLAC2D software. Results show that using piling system, deformation of tunnel wall and displacements of crown support decrease comparing to benching without additional treatment. But according to horizontal displacement magnitudes, it would be better to use another additional support such as invert struts combined with piling for completely controlling of horizontal displacements.

SYNOPSYS: In recent years, the most densely populated cities in the world have accelerated effort in developing underground space as a mode of transportation for eco-friendly and sustainable cities. However, it appears to become more difficult to use underground space in metropolitan cities due to existing underground structures. Consequently, it leads to development of underground space beneath existing underground structures and the underground structures become multi-layered vertically. Considering the fact, this case study aims to introduce the design and construction methodology of the largest tunnel station in Seoul, which has been constructed 15cm under the existing subway line 3 and the superannuated underground shopping complex within highly-congested area. To overcome the obstacles incurred by the site condition, for instance, neighboring construction, civil petition and severe traffic jam during the construction, the combined method of the TRcM(Tubular Roof construction Method) and the CAM(Cellular Arch Method) has been created and applied. Although this construction project was considered as the most difficult project ever in the history of the Korea's subway construction, the subway station has been constructed successfully without any damages on the adjacent structures and has launched from July 2009. 1. INTRODUCTION Seoul, the most populous city in Korea, has the population density of 16,582 people per square kilometer in 2009. Until the 1990s, Seoul had experienced rapid economic growth as well as population concentration, and decided to promote the development of underground space. The utilization had been focused on the shallow depth underground space by using the cut and cover method which was relatively easier and less intricate to apply. As a result, the most of shallow-depth underground space in urban areas has already been utilized for transportation, electric power, communication, water supply and sewer networks. Nowadays, these existing underground structures are considered as one of the major obstacles in development of underground space. Consequently, the cases of tunneling work under existing underground structures have been increasing rapidly. 2. PROJECT OVERVIEW The stage 1 of the new Subway line 9 has launched in July 2009 to ease the traffic flow between the west and the east part of the Seoul and to promote the use of underground space as a mode of transportation for the development of eco-friendly and sustainable cities by reducing air pollution and economic cost of traffic congestion. The stage 2 and stage 3 of subway line 9 will be completed in 2013 and in 2015, respectively. The stage 1 of subway line 9 starts from Gimpo Intl. Airport and ends in the Gangnam Area, the most urbanized area in the Seoul. The total length of the subway line 9 is 25.5 km and it has 25 stations. The 913 project of the stage 1 is composed of two subway stations (922 and 923 subway station) and the 1.78km of subway lines as shown in figure 1. The 923 subway station of the 913 project, which is named the Banpo(Express Bus Terminal) station, is located in the center of the life culture and transportation.

Abstract: Geotechnical instruments are integral part at power house cavern (PC) of Kiah Boshes project. Instrumentation data are collected during and after excavation and concreting period. Absolutely, extensometer is the main instrument in large underground spaces which install as soon as possible in excavation phase. Pressure cell, pedometer and linear displacement transducer are main instruments applied in concreting period. Two extensometer In order to achieve total displacement are installed before starting of PC excavation. We are analysis instrumentation data for powerhouse cavern of Kiah Boshes project to determine amount of omitted data which help to back analyzing and achieve actual rock mass properties. About 5 cm Styrofoam board in order to damping future rock mass displacement to concrete wall is installed between concrete and shotcrete surface. Also some opening anticipate for future ground anchor. According instruments data, stable condition achieve after concreting period. 1- INTRODUCTION Kiah Lishe pumped storage power plant is the first pumped storage project at Iran with capacity of 1000 MW. Power house cavern (PC) with 131m high, 24m width and 47m high is adjacent of guard gate and transformer caverns. PC is located in a sedimentary layers (Quartzite Sandstone and red Shale) and igneous masses (intrusive rock). Thickness of sedimentary layers is from some centimeter to about 1 meter. Some shear bands and two major joint set are affected rock mass [1]. 2- PC EXCAVATION PC has excavated and supported generally according to the New Austrian Tunneling Method (ATM). Vault admit exists on upstream side of PC which help to install two extensometer (E10 and E15) before starting of PC excavation. PC has excavated at two parts: top and benching. PC crown divided to three parts: upstream, center and downstream (figure 1). PC benching was started after installation of roof ground anchor (mono bar). PC invert lowering about 3 m in each sequence of benching, figure 2. PC's volume was 117700 cubic meters which excavated from Oct. 2004 until Feb. 2007 and concreting from July 2006 until July 2010. 2- MONITORING SYSTEM PC monitoring system consists of six instrumentation sections (figure 3). Two extensometer (E10 and E15) are installed before starting PC excavations (figure 4) and other instruments (extensometer, load cells and convergence meters) are installed during the excavation period. Therefore, for more extensometer installation delay cause omits some of actual displacement which is related to PC excavation. Concrete instruments such as pedometer, pressure cell and linear displacement transducer are installed during concreting period. 3- DATA INTERPRETATION According E15 date-displacement curve (figure 5) and sequence of PC excavation (figure 1 and 2): More than 15 percent of total movement wall occurred before that invert reach to elevation of extensometer. About 23 percent of total movement of PC wall occurred before that invert reaches to 1.3 m below of extensometer elevation. 4- ROCK-CONCRETE INTERACTION Some geotechnical instruments such as Pressure cell(figure 6-a), Liner displacement transducer(figure 6-b), Pedometer and Strain gage are installed in concreting phase of PC in order to monitoring rock concrete interaction [2].

Abstract: The stability of slopes can be assessed by a factor of safety, which is usually determined by a limit equilibrium method. In order to evaluate the factor of safety, we need such strength parameters as cohesion and the internal friction angle. In the monitoring of slope stability, displacements are commonly measured. Therefore, the strength parameters should be evaluated from the measured displacements. Sakurai and Nakayama (1999) developed a back analysis procedure for determining the strength parameters from the measured displacements. The back analysis procedure was successfully developed by introducing both an "anisotropic parameter" and "critical shear strain". Recently, on the basis of this back analysis procedure, a computer code called the "Universal Back Analysis Program for Slope Stability" (UBAPSS) has been completed. In this paper, UBAPSS is briefly described, and a case study is shown to demonstrate its applicability for assessing the slope stability at an open pit coal mine. The surface displacements were measured in the mine by GPS and the data were collected until failure occurred. The strength parameters were determined using the data obtained just one day before the failure occurred. The results of the back analysis indicate that the factor of safety becomes approximately 1.0. This means that the computer code UBAPSS is well applicable to the assessment of the stability of slopes. 1. INTRODUCTION The stability of slopes can be assessed by a factor of safety, which is usually determined by a limit equilibrium method. In order to evaluate the factor of safety, we need such strength parameters as cohesion and the internal friction angle. However, determining the strength parameters is not an easy task, because soil and rock have numerous geological and geotechnical uncertainties. However, the question of how to evaluate the strength parameters from the measured displacements is raised. To answer this question, Sakurai (1992) developed a back analysis procedure which can determine the mechanism of the slope deformation, whether it is sliding or toppling, the location of sliding planes, and the strength parameters, such as cohesion and the internal friction angle, from the measured displacements, even only from the surface displacements. The back analysis procedure was successfully developed by introducing both an "anisotropic parameter" and "critical shear strain". Recently, on the basis of this back analysis procedure, a computer code called the "Universal Back Analysis Program for Slope Stability (UBAPSS) has been completed. In this paper, UBAPSS is briefly described, and a case study is shown to demonstrate the applicability of the proposed back analysis procedure for assessing the slope stability at an open pit coal mine, where the surface displacements were measured by GPS and the data were collected until failure occurred. The strength parameters were determined using the data obtained just one day before the failure occurred. The results of the back analysis indicate that the factor of safety becomes approximately 1.0. This proves that the computer code UBAPSS is well applicable to the assessment of the stability of slopes.

Abstract: This paper presents a research which was carried out in order to analysis the stability of deviations binary tunnels at dam situated in the southwest of Iran. The excavation of underground spaces has been an important task for civil and mining engineers since the past decades for their wide range of applications. The diameter of each of these tunnels is 13.7 meters and they are around 1000 meters long. The tunnels are excavated in steps of consecutive cuts. They are passing through seven different geological zones with various specifications. In order to study the characteristics of these zones nine boreholes of total length of 904 meters have been drilled. Around 140 various laboratory tests have been conducted on the core samples. Testing and analyzing the cores taken from the boreholes have resulted in series of data required for the investigation. These data reveals physical and mechanical properties of the seven various rock zones, including RED, joint sets and joint properties. Based on the collected data the values of RM and Q and therefore the class of the rocks have been determined for all seven zones. Stability analysis has been conducted and appropriate supports have been offered for both tunnels by RM and Q methods. Based on the ratings ascribed to each zone by any of the two methods a relationship has been driven between RM and Q for this particular project. 1- Introduction Rock mass characterization is normally carried out through the application of empirical classification systems which use a set of geotechnical data and provide an overall description of the rock properties. Moreover, they allow obtaining other important information like support needs, stand-up time, geotechnical parameters among others [1]. Different classification systems have some well known drawbacks and limitations due mainly to their empirical base [2]. However, they are still very useful in practice. Therefore, there is a need to improve their efficiency. Two of the most used classification systems are the RM Rock Mass Rating and the Q-system [1].The RM and Q systems have evolved over time to better reflect the perceived influence of various rock mass factors on excavation stability [3]. This paper discusses the evolution of these systems, as well as problems associated with estimating the Q, RM indexes for water deviation binary tunnels in the Bakhtiyari dam of Iran. 2- Site geology Bakhtyari dam site is in the southwest of Iran, almost 70 km North-East of Andi mesh town (Khuzestan province) and almost 65 km South-West of Doored town (Lodestar province). The dam axis lays at 290725 E and 3648729 N points. Figure1 shows the Location of the project area [4]. This formation consists of a series of asymmetric folding and faults The project area is covered by the sedimentary bedrocks of Larval and Faro formations. The Larval Formation is divided into 7 units from Sv1 (oldest) to Sv7 (youngest). At project site the Faro Formation is younger than the Larval Formation and is divided into two units [5].