TMMOBABSTRACT: Support system design has always been a critical engineering problem for large-scale tunnels excavated withinfault zones. In fault zones, it is possible to encounter face and ceiling stability problems encountered during thetunnel excavation in the short term and failures in the support systems due to squeezing in the long term. For thisreason, when designing support systems, short-term and long-term parameters should be considered. The mostimportant factors in selecting the support system to be installed are to describe the geological conditions well andthe correct selection of geotechnical design parameters. Therefore, the main purpose of this study is to investigate the support design that considers the short- and long-term parameters for the Ankara-Istanbul High Speed TrainProject, T36 tunnel excavated within the fault zone. The total length of the T36 tunnel is 4100 m, and excavation andsupport works have been completed under a maximum overburden thickness of 180 m. In the fault zone transition,the supports were made under the overburden thickness of 115 m, and face stability problems were encountered inthe short term and squeezing problems in the tunnel in the long term. In this study, the causes of deformations in thetunnel affecting the tunnel in the short and long term are discussed and numerical analysis and support systems areexamined. Moreover, the criteria for fault zone crossings, which is one of the most important issues for tunneling,are discussed.
ABSTRACT: In this study, the changes in the index and strength properties of calcarenites, which are widely used as buildingstone in the Turkish Republic of Northern Cyprus, after being subjected to high temperatures between 200 and1000oC, and the effects of high temperatures on microstructure of the calcarenite were investigated by using electronmicroscope images. In order to represent a real fire incident, the samples were heated using the temperature-timecurves recommended by Eurocode, and left to cool at room temperature after 2 hours of exposure at target temperature.After the experimental studies, it was observed that there was no significant change in density and weight loss valuesup to 600 oC. After 600oC, a sudden decrease in density was recorded, at 1000 oC the density dropped below 1 due to microcracks. Likewise, the weight loss value reached 41% depending on the calcination process observed in calcites.P-wave velocity and tensile strength values decreased continuously depending on the temperature. However, thisdecrease became more pronounced after 600 oC and reached the most prominent level after 800 oC. In SEM images,discontinuity formation was observed due to the agglomeration that developed especially after 600 oC. This situationis considered as the main reason for the decrease in strength. In experimental studies applied by Eurocode, it isstated that the temperature of a fire that will occur outside the building will not exceed 680oC, and in a fire that willoccur indoors, the temperature will exceed 1000 oC. For this reason, it is recommended that calcarenites, which arethe subject of the study, are used only as outer coatings in buildings
ABSTRACT: Many developed and developing countries use rail systems in addition to road systems in public transportation.One of the most frequently used types of these rail systems is the light rail systems (LRS). The routes of the LRS aregenerally preferred on the existing road route. This situation creates some problems in terms of ground conditions.Since the rail system vehicle weights and passenger capacities are much more than road vehicles, the loads theyapply to the ground are also higher. However, deformations occurring on the road surface generally affect vehiclesand passengers in terms of comfort, while small deformations on rail systems can bring major problems such asaccidents and deaths. For this purpose, it is very important to investigate the ground structure of the rail systemroute and to analyze the suitability situation in order to prevent these problems. In this study, the suitability of theLRS route planned to be built in the city center of Erzurum in terms of physical properties of soil was analyzed. Inthe analysis, it was suggested that some locations were problematic in the results obtained by using the basic rotary drilling, multichannel analysis of surface waves (MASW), and microtremor methods and ground improvement orrevision of the route was suggested for these points. Where the ground condition is not suitable, an alternative routehas been created by taking passenger`s demand in to consideration.
ABSTRACT: The numerical modelling techniques provide quite useful insights about how the interaction between engineeringstructures and host rocks develop. On the other hand, the representation of the real rock domain depends on thereliability of the numerical model used. For this reason, micro parameters of a model must be calibrated accuratelyand model results must be irrespective of the model resolution and/or dimension. Recently, the discrete element method (DEM) is mostly used to determine the mechanical behaviors of the complex solid materials such as rocks.The purpose of this study is to investigate the effects of required micro parameters for developing a numerical model-based on such method- on macro mechanical properties and deformation behaviors of a rock. Every micro parameteris analysed individually by performing a number of uniaxial compressive, uniaxial tensile, and triaxial compressivetest simulations through Yade open source DEM code. Obtained results show that the uniaxial compressive strengthof the rock (UCS) mostly depends on micro-cohesion while the uniaxial tensile rock strength (UTS) primarilydepends on tensile strength between the particles. Furthermore, both strength properties are in relation to the microelastic modulus and stiffness ratio. The deformation properties such as Youngs modulus (E) and Poissons ratio(ν) are directly controlled by the micro-elastic modulus and stiffness ratio. The slope of the rock failure envelope isincreasing with an increase in micro-internal friction angle and the strength ratio (UCS/UTS) is arranged based onthe coordination number assigned at the beginning of the simulation. This study presents the constituents of strengthand deformation properties of a rock according to the interaction between the model parameters. The results provideapplicable, practical and guiding insights in terms of developing numerical models which predict the rock behaviorsbefore the construction of engineering structures
ABSTRACT: 670 pillar is a geological barrier that will trap the rock block falling and rolling from the deformation zone of the Eynez fault as well as to prevent the materials belonging to the landslides to be formed along the fault zone from reaching the coal production area It forms the foot wall of Soma-Eynez and consists of Neogene aged marls The toppling failures observed in the 670-pillar´s slopes threatened the safety of excavation works for coal production in the open pit t. The maximum runout distances of rock fragments that had toppled, fallen and rolled at different slope heights as a result of the mentioned mass movements were determined using computer softwares. Theproject excavation limit for the open pit coal mine was determined by considering the runout distances calculated for different slope heights n this work, toppling failures observed in the 670-pillar´s slopes were investigated both kinematically and numerically, using stereographic projection and different computer softwares, respectively. Safety factors obtained from different softwares for the same slope geometries were compared and the effect of frictionangle (ɸ) and cohesion (c) values of the joint surfaces on safety factor that cause toppling failures were investigated. In addition, the time-dependent changes of joint aperture increase rate obtained from 20-deformation measurement points installed on the cracks causing toppling failures were investigated. The areas where the joint aperture increaserate is highest and the areas where the toppling failure is observed in the pillar´s slope were associated.
ABSTRACT: In this study, the relationships between shear strength of a blocky rock mass consisting of pyroclastic depositsand the fractal dimension of the blocks within n the rock mass were investigated. Within the scope, triaxial shear testswere performed on specimens extracted from a blocky pyroclastic rock mass that defined as bimrock in termsof jeo-mechanical description. Thereby, cohesion (c) and internal friction angle (ɸ) values of the blocks withinin the rock mass were calculated through the fractal dimension solutions and digital image processing analysis Inaddition, uniaxial compressive strength of the rock and d the matrix component of this rock mass were determined Theresults revealed that there are positive and negative linear relationships between DR and c, ɸ and between DF and c,ɸ pairs. It is determined that while the values of both DR and DF increase, the values of ɸ increase and vice versa forcohesion The increase of ɸ with the increase of DR is an indication that the friction also increases by applied shearstresses due to the increase in the roughness of the block surfaces. Finally the increasing of DR yielded an increasein the sum of the surface areas of the contacts between he matrix and blocks. Thus, the cohesion decreases due to the probable increase of weakness zones that loosen the rock mass.
ABSTRACT: Quantitative estimations of climate changes on hydrological processes help to understand and manage waterresource problems such as floods and droughts in the future. This study aims to present the preliminary results of astudy to determine the mpact of climate change on river flow to develop sustainable watershed management plans and to evaluate the possible urban water use and environmental impacts to prepare policies to mitigate its negativeimpacts. In this study the Soil and Water Assessment Tool (SWAT) was used as a hydrological model to predicthydrological effects of climate change to better understand and solve future water resource problems. In this context,firstly the Soil and Water Assessment Tool (SWAT) was operated on the e Yuvacık Dam Basin in Marmara Region toreveal the present hydrological situation. The hydrological model was then simulated by using the climate changedata that have 20 km spatial resolution between 2021-2099 years based on RCP 4.5 and RCP 8.5 scenarios thatwere produced by the General Directorate of Meteorology. Thus, the effects of climate change on the amount ofwater and sediment were estimated between these years. According to the RCP 4.5 and RCP 8.5 scenarios, 2.23% and 2.062% decrease in the average annual rainfall 1.24 0.03 of increase in temperature values werepredicted, respectively. However, an increase in precipitation was expected between April August. The averagemonthly flows (between 2006-2014) of the e Kazandere, Kirazdere Serindere rivers recharging the Yuvacık Damin the basin is 0.55, 1.28 1.94 m3/s, respectively. Corresponding modelled flow values based on RCP 4.5 RCP 8.5 scenarios for 2021-2099 period, for Kazandere, Kirazdere Serindere are 0.14 0.17 m3/s, 0.41 0.33 m3/s, 0.86 0.68 m3/s, respectively. These values show significant decrease in flow rates o the rivers in the future. Moreover the peak flow values of the streams especially for Kazandere Kirazdere decrease from 8 to2 m3/sec The amount of the monthly average of sediment measured at the Serindere stream station for the years2010-2013 was 49 tons, while it was calculated as 247.58 tons based on RCP 4.5 332.21 tons based on RCP 8.5for 2021-2099 period. According to both scenarios, an increase in the predicted rainfall between April August, an increase in temperature will cause mechanical erosion in the basin. Thus the amount of sediment carriedby flow is expected to increase. The Yuvacık Dam is used for providing irrigation drinking water requirementsof Sakarya Izmit provinces, for the prevention of flood as well as for water management during droughtperiods. Therefore,the decrease in the flow rates of the streams recharging he dam will cause a decrease in thewater volume of the dam, hence the future water management planning should be made for the crop pattern in theirrigated areas of the dam for the drinking water usage. Furthermore, the decrease in the flow rates will causeto decrease the forest areas in the basin which in turn will lead to an increase in the amount of erosion. This willcause an increase in the amount of sediment coming to the reservoir thus the service life time of the reservoir willbe shortened