Balastsız Üstyapılarda Aplikasyon Ve Deformasyon Ölçmeleri

Abstract

Son yıllarda özellikle balastsız üstyapıların aplikasyonunda ve deformasyonların izlenmesinde doğruluk talepleri artmaya başlamıştır. Buna paralel olarak demiryolu ölçmelerinde, özel ölçme sistemlerinin geliştirilmesine doğru bir yönelim gözlenmektedir. Bu tez çalışmasında raylı sistem hatları aplikasyon, deformasyon ve rölöve ölçmelerinde kullanılan klasik yöntemlerle, yeni geliştirilen cihazlarla yapılan özel ölçme sistemlerinin bir kıyaslaması yapılarak, farklılıklarının ortaya koyulması amaçlanmıştır. Tez kapsamında öncelikle genel hatlarıyla demiryollarının ortaya çıkışı, diğer ulaşım sistemleri arasındaki konumu ve üstün yanları üzerinde durulmuştur. Daha sonra balastsız üstyapı sistemlerinin balastlı sistemlerle karşılaştırması yapılmış ve balastsız üstyapı elemanları incelenmiştir. Raylı sistemlerin çevresel, geoteknik ve işletme ile ilgili sorunlarına özel çözümler getirmek için geliştirilen farklı balastsız üstyapı sistemleri açıklanmıştır. Yatay ve düşey kontrol ağlarının oluşturulması açıklanıp, genel aplikasyon tanımından ve klasik aplikasyon yöntemlerinden bahsedilmiştir. Sonraki bölümde deformasyon tanımı yapılıp, raylı sistemlerde meydana gelen deformasyonlar, malzeme deformasyonları ve geometrik deformasyonlar olmak üzere iki grupta incelenmiştir. Yatay ve düşey deformasyonları belirlemek için, klasik jeodezik yöntemlerle yapılan deformasyon ölçmeleri üzerinde durulmuştur. Uygulama kısmında raylı sistemlerde aplikasyon ve deformasyon ölçmeleri için geliştirilen özel ölçme sistemi incelenmiştir. Bu sistemin bileşenleri ve çalışma prensibi açıklanmıştır. Balastsız üstyapıların aplikasyon, deformasyon ve rölöve ölçümlerinde kullanılan klasik jeodezik yöntemler ile sadece bu iş için üretilmiş özel ölçme sistemleri kıyaslanmıştır. Bu kıyaslama yapılırken yurt dışında bu sistemlerin kullanıldığı projelerden örnekler verilmiştir. Sonuç olarak aplikasyon ölçmelerinde klasik yöntemler kullanılarak günde 54 metrelik hat ölçülebiliyorken, özel ölçme sistemi kullanıldığında bunun 400 metreye kadar çıkabildiği ve bununla beraber ulaşılan doğruluğun da yükseldiği görülmektedir. Aynı şekilde deformasyon ölçmeleri için de hem daha iyi doğruluk değerlerine ulaşılmakta hem de bir saatte ölçülebilen hat uzunluğu 50 metreden 600 ila 1200 metreye kadar çıkmaktadır. Rölöve ölçümlerinde klasik yöntemlerle saatte 100 - 200 metrelik hattın alımı yapılabiliyorken özel ölçme sistemi ile 800 - 1200 metrelik hattın alımı yapılabilmektedir. Yapılan çalışmanın sonucunda görülmüştür ki özel ölçme sisteminin kullanımı klasik yöntemlere göre daha yüksek doğruluk ve hız sağlarken ekip sayısının da azalmasına imkan vermiştir.

One of the most important mile stone of transportation history is undoubtedly the foundation of railways. Railroads are the most sustained transport system among the others. The main reason for this is the trains can reach maximum speeds with minimum energy consumption. Beside that they give minimum damage to the environment with electrical attraction and low land use. Despite these features since highways and airplanes offer more flexibility and alternatives in every aspect, utilization of these transport types always increased. This competition requires a continuous development of railways. During the growing of railways current superstructure design of them always developed and changed. Nowadays most of the railways slab tracks are being used in most of the railways. Low cost investing are the most important reason for this. However ballastless tracks are making up the difference with their low maintenance costs and long service life and becoming more feasible in 5 to 7 years. Also it ensures higher safety against lateral forces and accommodation of higher axle loads. The slab track can compensate any excess in superelevation and in cant deficiency with freight trains or passenger trains without fears for dislocation of the track. The components of ballastless tracks can be counted as, rails, sleepers, fastenings, rail seating pads, transportation layers and protection layers. The rails provide smooth, stepless, low resistance and constant bearing surface for railroad cars at the same time they transfer the loads to sleepers. Sleepers provide sufficient mechanical endurance in horizontal and vertical to structural bearings. Fastenings and rail seating pads between rails and sleepers help damping the vibrations and gain flexibility to superstructure. Beneath these connections there is a track supporting layer. Instead of ballast in ballastless track, concrete or asphalt supporting layers are being used. Under the transportation layer there is a protection layer connected with bitumen to increase the capacity of load carrying system and provide the distribution of upper loads. Many slab track systems are enhanced to bring special solutions to geotechnical and operation problems of railway systems. Slab tracks can be categorized as two main groups according to their slab types. One of them is supported slab and the other is continuous slab. In supported slabs, sleepers can be embedded to track supporting layers or they can on the layer or they can never be used as well. In the systems without sleeper, instead of sleepers, cast concrete boards or single piece molded concrete are used. In continuous slab, rails are embedded to the holes in concrete track supporting layers. The basic principle of this system is the constant elastic support of rails. This type of pavement can be constant embedded or constant secured rails. Whatever the slab track system is, the set out must be done with high accuracy in order to provide the trains to navigate comfortably and securely in high speeds. Set out is the process of adaptation of a civil engineering construction to the field so that it can meet the requested accuracies with designed horizontal and vertical geometry. In high cost engineering projects such as railway systems, many geodesic measurements are needed before, during and afterwards of construction. Foundation of the three dimensional control networks to the field should be planned according to set out process. The first step of set out process is to create a triangulation and leveling network to involve and meet the wanted accuracies. After that these are going to be used as reference points of set out to build the slab track. For the transfer of track geometry to the field, horizontal and vertical control network set out support points must be used. Afterwards set out measurement method would be chosen considered the requested accuracy, the field conditions, the positions of created points and set out points according to each other and the hardware which will be used. After railways are opened some deformations that can affect the security and comfort would occur. Therefore these deformations are needed to be identified and maintained in order to keep the comfort and security in a certain level. The measurements that evaluate the geometrical changes, the motions around environment and the effect of these motions are called 'deformation measurements'. Geodesic methods of deformation are based on evaluation of periodic network GPS measurements that can determine horizontal and vertical deformations. When classical geodesic methods are thought, geodesic control network method, precise benchmark method and alignment method can be used for horizontal deformations. For the vertical deformations, precision geometrical leveling method, hydrostatics leveling method or trigonometric leveling method can be used. Many companies have developed new methods for set out and deformation measurements of railways to replace the classical geodesic measurements. At the end of these studies, various instruments are developed that can determine the measurement hardware and line geometry when the rails are in motion. These measurement systems can be used in new line set out measurements and determination of horizontal and vertical geometry and deformation of existing lines. In the measurement system, there are sensors and locator devices to be able to determine inner parameters and navigation accuracy of railways. The sensor systems are, gauge sensor, odometer and inclinometer. For the navigation system, total station or GPS can be used according to conditions. After the construction of measurement system on rail line, the system connects wirelessly with total station and a point with known coordinates. Total station connects the mobile measurement system with polygon network and thus it transmits three dimensional coordinates of reflector to the system. Engine-driven total station always automatically follows the reflector as long as the system moves among the rails. Through the computer and measurement software, the coordination information coming from total station syncs with the line information coming from system sensors and can be shown in computer screen real time. Since the line geometry has been identified in computer before the measurement software can make the necessary calculations and transmit the difference between measured line location and necessity location. Within the scope of this thesis, classical geodesic methods and special measurement systems which are designed just for this goal are compared for slab track set out, deformation and roleve measurements. When these comparisons are being made, examples have been given from abroad projects, specifically the ones that these systems are used. The criterions between the methods are cost, time and accuracy. According to results, track which is 54 meters long can be measured in one day by using classical geodesic methods in setting out measurements. Special measurement system can handle 400 meters long rail part daily. Meanwhile accuracy will increase despite scaling up velocity. In deformation measurements, track length which can measured is increased from 50 meters to 600 - 1200 meters as well as incresing accuracy. Relief measurements can be done for 100-200 meters long track line per hour by using classical geodesic methods. By using special measurement system, 800-1200 meters long track line can be measured hourly. As initial costs for special measurement systems are high-priced, this technique reduces number of employees and working hour effectively. Besides that, due to its high capacity to automation and reduction of human factor, this systems assure high precision measurements both relative and absolute.