Kayalar için Bazı Kazılabilirlik Yöntemlerinin Değerlendirilmesi ve Gsı ile Nokta Yükü Dayanım İndeksini Esas Alan Grafik Yöntemin Tahmin Performansının Araştırılması

Abstract

Determining the excavation method, which is applied in engineering excavations in rock environments, enables to control construction period, manufacturing stages, costs, production quantity, aesthetic conditions, mid and long term safety factors and environmental impacts, and therefore, it takes a place among the most significant issues that concern several engineering disciplines. Despite the fact that certain methods and/or classification systems have been recently developed in order to determine which one of the major excavation methods (digging, ripping, breaking and blasting) should be used at any site, certain limitations have been encountered with respect to their performance in estimating the applicable excavation method. In this study, by considering these limitations, it is aimed to investigate the prediction performance of the existing multiparameter excavation methods and to modify the method based on Geological Strength Index (GSI) and point load strength index (Is(50)) using a database. For this purpose, a database was established for 280 locations considering the specified criteria and the geotechnical data related to particular project sites located in Turkey where the applied excavation methods are known, and subsequently this database has been utilized in the assessments. As a result of the evaluations conducted using the database, it was understood that no data has matched with the excavation types estimated as per the excavation methods determined by considering the fracture frequency and Is(50) excluding some locations where ripping was made. The main reason for this situation is that the success of the estimation of the proposed boundaries between the types of excavations in these systems have failed to a certain extent due to the performance increase in the performance of the construction machines recently, and due to suggestions of these boundaries on the basis of a limited database. On the other hand, the other excavation system has successfully estimated the sites, where the methods of digging and ripping could be applied; however, it could not achieve the same success with respect to the methods of breaking and blasting. The mismatch observed in the breaking method may result from the fact that the ripping method has not been applied systematically in the construction industry in Turkey in places, where rocks have suitable properties and replacing the breaking method and applying the blasting method where the breaking method is not economical / practical. The other method examined within the scope of this thesis takes GSI and Is(50) into account. The method was modified using the database obtained in the thesis study because of the following reasons two different GSI based excavation diagrams have been used in order to determine the excavation type according to two threshold Is(50) values, the boundaries between the excavation methods, set forth in such diagrams from each other, have been drawn using insufficient data, a subjective GSI determination approach based on visual evaluation has been used in this method. As a result of such modification, it was understood that distinct boundaries between the excavation types are ontained in a manner that all data pairs included in the substantial database formed during the thesis study are prominently grouped and the main four excavation types are distinguished; and that it is possible to estimate the excavation method that can be applied at any site from a single excavation estimation chart by using the GSI and Is(50) values.