Saffet Yagiz

• PhD
• Faculty at Nazarbayev University

Cutters are the primary tools utilized by tunnel boring machine (TBM) mounted on its rotating, circular cutter head to excavate the tunnels. Cutters experience continuous wearing as the boring of the tunnel takes place and need to be replaced when worn out, which presents a critical component in the cost assessment. In some rock formations, this is...

Going underground is one of the inevitable elements of modern transportation infrastructure in sustainable development. Despite the economical and safety benefits of a tunnel boring machine (TBM) when using them to construct tunnels in a broad range of geological conditions, the prediction of TBM performance, especially the rate of penetration (ROP...

The Sakhrei Hotel, located in Khorramabad city (Lorestan Province, western Iran), is a civil structure under construction on a limestone foundation. Considering the occurrence of freeze–thaw (FT) and acid attack (AA) in Khorramabad, an in-depth study is required to evaluate the durability of limestone against these deterioration processes. To this...

Tunnel boring machines (TBMs) are one of the most widely used means of excavating tunnels in rock masses in a more economical, faster, and safer manner. Despite the recent technological advances in tunneling, a reliable estimation of the TBM rate of penetration (ROP) still remains a challenging task. This study aims to develop empirical models for...

The prediction of tunnel boring machine (TBM) performance from the rate of penetration (ROP) point of view has yet to draw a lot of attention since it is one of the main challenges for excavation with TBMs. This study examined six tunnels excavated with TBM to develop predictive models of the ROP estimation using five algorithms: Gradient Boosting...

The production rate of mechanical excavators such as tunnel boring machine (TBM) and roadheader depend on the geotechnical properties of rock, machine specifications and operational parameters. TBMs are being utilized for the construction of various tunnels for the purpose of access, conveyance of ore and waste, drainage, exploration, water supply...

The estimation of disc cutter wear (CW) remains a complex problem in mechanized tunneling using tunnel boring machines (TBM), despite the development of numerous TBM performance models. This research aimed to estimate the cutter life index (CLI) as an index to predict the CW by developing predictive models based on two machine learning algorithms,...

Performance analysis of drilling machines and estimating drillability of rock is a critical process for every drilling operation, since estimating the drillability by means of the rate of drilling (DR) has a significant impact on the cost and time scheduling of rock excavation projects. The aim of this study is to estimate the DR of both diamond an...

TBM performance prediction from the rate of penetration (ROP) point of view has yet to draw a lot of attention since it is one of the main challenges for mechanized excavation with tunnel boring machines (TBMs). In this study, five algorithms, Gradient Boosting (GB), eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), A...

Penetration rate is one of the most critical parameters affecting the performance of TBM machines and it is complicated to predict due to uncertainty in excavating operations and geological parameters. In this paper, using Monte Carlo simulation, the penetration rate is predicted, and the sensitivity of the parameters affecting the penetration rate...

Soft sedimentary rocks are frequently found in many mountainous regions of the world like Zagros Mountains located in the south and west of Iran, where most of Iran's water conveyance projects have been constructed or are under construction. These rocks usually contain considerable amounts of different types of clay minerals. The clay mineral‐rich...

The soft sedimentary rocks are frequently found in the mountainous regions of the world like Zagros Mountains located in the south and west of Iran, where most of Iran's water conveyance projects have been constructed or are under construction. These rocks usually contain considerable amounts of different types of clay minerals. The clay mineral-ri...

Due to the different challenges in rock sampling and in measuring their thermal conductivity (TC) in the field and laboratory, the determination of the TC of rocks using non-invasive methods is in demand in engineering projects. The relationship between TC and non-destructive tests has not been well-established. An investigation of the most importa...

Featured Application The proposed models in this paper can be used to estimate the cutter life index for estimation of cutter wear and life where the actual index is not available. Abstract The wear of cutting tools is critical for any engineering applications dealing with mechanical rock excavations, as it directly affects the cost and time of pr...

This study aims to develop several equations for predicting penetration rate (PR) and advance rate (AR) of tunnel boring machine (TBM) in fresh, slightly weathered and moderately weathered zones in granite rock mass. To reach study objectives, 12,649 m of the Pahang- Selangor Raw Water Transfer (PSRWT) tunnel in Malaysia was studied in both laborat...

Field penetration index (FPI) is one of the representative key parameters to examine the tunnel boring machine (TBM) performance. Lack of accurate FPI prediction can be responsible for numerous disastrous incidents associated with rock mechanics and engineering. This study aims to predict TBM performance (i.e. FPI) by an efficient and improved adap...

This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in clay. The gated recurrent unit (GRU) neural network is adopted to formulate the forecast model and learn the potential rules in the field observations using the Neste...

Raise boring machines (RBMs) are commonly utilized for drilling of shaft and other inclined structures in mining and civil applications. This paper aim to introduce several empirical equations to estimate the performance and operational parameters of RBMs. For the aim, datasets having rock properties including uniaxial compressive strength (UCS), B...

Rock brittleness is one of the most significant properties of rock having a major impact not only on the failure process of intact rock but also on the response of rock mass to rock excavation. In fact, the brittleness is a combination of rock properties including not only the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS)...

Hard rock pillar is a crucial rock mass structure to maintain the stability of underground mine. It needs of special attention to analyze its stability from the point of rock mass quality. In this paper, the geological strength index (GSI) representing the rock mass quality of the hard rock pillar is examined as a new influence factor of stability,...

To date, the accurate prediction of tunnel boring machine (TBM) performance remains a considerable challenge owing to the complex interactions between the TBM and ground. Using evolutionary polynomial regression (EPR) and random forest (RF), this study develops two novel prediction models for TBM performance. Both models can predict the TBM penetra...

This study constructs and verifies a new statistical meta based-model to predict tunnel-boring machine (TBM) performance, namely, polynomial chaos expansion (PCE). To test the validity of the proposed PCE, two well-known mathematical models, namely, response surface method (RSM) and multivariate adaptive regression spline (MARS) were developed. Acc...

Soft rock formations are widespread throughout the mountainous regions of the world including the mountains of western and southern Iran. Therefore, it is very common to pass through soft rock formations while building long tunnels for various purposes in the mountainous regions. The soft sedimentary rocks are frequently found in Zagros Mountains l...

The advance rate (AR) of a tunnel boring machine (TBM) in hard rock condition is a key parameter for the successful accomplishment of a tunneling project, and the proper and reliable prediction of this parameter can lead to minimizing the risks associated to high capital costs and scheduling for such projects. This research aims at optimizing the h...

This paper presents an experimental study to assess the effects of physical and mechanical properties of carbonate rocks and diamond/metal matrix characteristics on performance and tool life of segmented circular sawblades. For this purpose, pertinent rock properties including strength, hardness, abrasivity, water absorption, porosity and unit weig...

Brittleness is one of the most important properties of rock which has a major impact not only on the failure process of intact rock but also on the response of rock mass to tunneling and mining projects. Due to the lack of a universally accepted definition of rock brittleness, a wide range of methods, including direct and indirect methods, have bee...

The aim of this study was to estimate brittleness of intact rock by applying differential evolution (DE) algorithm and then to compare the results obtained from the optimum model with literature. For this aim, several models including linear and nonlinear were developed for predicting the brittleness via DE algorithm using the dataset obtained from...

This paper aims to propose predictive equations for estimation of rock brittleness as a function of intact rock properties including rock density (r), Schmidt hammer (Rn) and wave velocity (Vp) using two optimization techniques, artificial neural network (ANN) and FA-ANN (Firefly Algorithm and ANN). Using ANN and FA-ANN techniques, 10 different mod...

Estimating the field penetration index (FPI) is an essential task in tunneling as the FPI is used to determine the tunnel boring machine (TBM) performance. In this study, fuzzy inference system (FIS) modelling is implemented to predict the FPI. Several models including fuzzy clustering and knowledge-based models were proposed. Data from the Queens...

This study aims to develop several optimization techniques for predicting advance rate of tunnel boring machine (TBM) in different weathered zones of granite. For this purpose, extensive field and laboratory studies have been conducted along the 12,649 m of the Pahang – Selangor raw water transfer tunnel in Malaysia. Rock properties consisting of u...

Determining the rock brittleness is often needed in a wide range of rock engineering projects; however, direct measurement of the brittleness are expensive, time consuming and also the test devices is not available in every laboratory. Due to that, assessing the brittleness of rock as a function of some rock properties such as uniaxial compressive...

The rock quality designation is an important input for the analysis and design of rock structures as reliable spatial modeling of the rock quality designation (RQD) can assist in designing and planning mines more efficiently. The aim of this paper is to model the spatial distribution of the RQD using the multi-Gaussian kriging approach as an altern...

The degradability of rocks is among the features of great importance in any projects relevant to geological, mining, civil or environmental. Slake durability is a measure of degradability of rocks due to the process of mechanical, physical and chemical breakdown. The aim of this study is to assess the influence of pH of testing liquid on degradabil...

Durability of carbonate rocks in terms of weathering is very important for their usability. Resistance of these types of rocks against weathering could be measured in laboratory conditions by slake durability index (SDI) tests. Although SDI tests are commonly carried out by application of two cycles, studies concerning application more then two cyc...

One of the essential tasks in the excavation of tunnels with TBM is the reliable estimation of its performance needed for the planning, cost control and other decision making on the feasibility of the tunneling project. The current study aims at predicting the rate of penetration (RoP) of TBM on the basis of the rock mass parameters including the u...

Brittleness of rock is one of the most critical features for design of underground excavation project. Therefore, proper assessing of rock brittleness can be very useful for designers and evaluators of geotechnical applications. In this study, feasibility of genetic programming (GP) model and non-linear multiple regression (NLMR) in predicting brit...

The Queens Water Tunnel No. 3, stage 2 having 7.5-km length and 7-m diameter, is excavated by a high-power tunnel boring machine (TBM) underneath Brooklyn and Queens area for distributing freshwater throughout the New York City, USA. This paper offers a review of the project by considering the TBM performance and rock mass interaction. Using the in...

The original version of the article contained some errors in order of generated equations. To get rid of them, Table 4 and Fig. 15 should be taken account as herein (Table presented) (Figure presented).

The uniaxial compressive strength (UCS) and Young’s modulus (E) of rock are important parameters for evaluating the strength, deformation, and stability of rock engineering structures. Direct measurement of these parameters is expensive, time-consuming, and even infeasible in some circumstances due to the difficulty involved in obtaining core sampl...

The aim of this study is to develop prediction models for estimating tunnel boring machine (TBM) performance using various optimization techniques including Differential Evolution (DE), Hybrid Harmony Search (HS-BFGS) and Grey Wolf Optimizer (GWO) and then to compare the results obtained from introduced models and also in literature. For this purpo...

The paper reviews the history of the punch penetration test as a laboratory method that could be conducted on intact rock sample for estimating the penetration rate of machines such as tunnel boring machines (TBMs) and microtunneling boring machine (MTBM) in rock mass. It discusses some of the methods that have been used to evaluate the test result...

Uniaxial compressive strength (UCS) of rock is crucial for any type of projects constructed in/on rock mass. The test that is conducted to measure the UCS of rock is expensive, time consuming and having sample restriction. For this reason, the UCS of rock may be estimated using simple rock tests such as point load index (I s(50)), Schmidt hammer (R...

The aim of this paper is to investigate the engineering properties of travertines extracted in the City of Denizli surroundings in Turkey. For this reason, different type of block travertines, including shrub, noche, onyx and reed were collected from quarries and then obtained block stones were prepared and tested according to international testing...

With widespread increasing applications of mechanized tunneling in almost all ground conditions, prediction of tunnel boring machine (TBM) performance is required for time planning, cost control and choice of excavation method in order to make tunneling economical. Penetration rate is a principal measure of full-face TBM performance and is used to...

IntroductionPrediction of tunnel boring machine (TBM) performance is crucial for mechanized tunneling, since TBM performance has an influence on duration and costs of the project. Analysis of TBM performance includes the assessment of the rate of penetration, advance rate and utilization, (the percentage of shift time that actual boring activity oc...

Predicting the penetration rate of a tunnel boring machine (TBM) plays an important role in the economic and time planning of tunneling projects. In the past years, various empirical methods have been developed for the prediction of TBM penetration rates using traditional statistical analysis techniques. Soft computing techniques are now being used...

Denizli ili çevresinde işletilen traverten, kayraktaşı, kireçtaşı gibi doğaltaşlar, bina ve yapıtaşı olarak kullanılmaktadır. Aynca, işletilebilir potansiyele sahip olmalarına rağmen işletilmeyen kireçtaşı ocakları da mevcuttur. Bu çalışmada, Denizli ili'nin kuzeydoğusunda, Başçeşme ve Yenibağlar arasında yüzlek veren Başçeşme Fosmasyonu'nun dolomi...

Prediction of utilization based on rock mass properties is critical for any mechanized tunneling project, since the utilization have an influence on duration and costs of project. Using some case studies including Queens, Milyang, Manapouri, Karaj, Varzo, Maen, Pieve mechanized tunneling project around the world, the attempt is made to estimate uti...

Sampling strategies which have very significant role on examining data characteristics i.e. imbalanced, small, exhaustive have been discussed in the literature for the last couple decades. In this study, the sampling problem encountered on small and continuous data sets is examined. Sampling with measured data by employing k-fold cross validation,...

Understanding rock material characterizations and solving relevant problems are quite difficult tasks because of their complex behavior, which sometimes cannot be identified without intelligent, numerical, and analytical approaches. Because of that, some prediction techniques, like artificial neural networks (ANN) and nonlinear regression technique...

Rock brittleness is an important rock characteristic, pertinent to predicting rock fragmentation behavior, energy consumption in rock cutting, and selection of proper cutting geometry. While brittleness is typically well understood as a concept, there is no universally accepted measure for this rock characteristic and often a combination of rock pr...

Successful application of a TBM in a project requires investigations both on the ground conditions and the machine and backup system design features. Adverse rock mass conditions like mixed face condition, water problem, instability of rock have a great role in TBM downtimes and reduce the machine utilization considerably. In this paper, main rock...

The paper reports a study to assess the relationship between slake durability indices and uniaxial compressive strength, Schmidt hardness, P-wave velocity, modulus of elasticity, effective porosity, water absorption and dry and saturated unit weight for seven types of carbonate rocks obtained from south west Turkey. It was found that the dry unit w...

P-wave velocity test, a non-destructive and easy method to apply in both field and laboratory conditions, has increasingly been conducted to determine the geotechnical properties of rock materials. The aim of this study is to predict the rock properties including the uniaxial compressive strength, Schmidt hardness, modulus of elasticity, water abso...

Abstract The aim of this study is to predict the performance of tunnel boring machines (TBMS) using particle swarm optimization technique (PSO). With this aim, a database including intact rock parameters comprising of strength and brittleness, and rock mass properties such as distance between planes of weakness and orientation of discontinuities,...

There are various type of building stone extracted at stone quarries in the city of Denizli surroundings. Travertine, limestone and schist quarries are the most common in the area. Schist that is one of the units of Menderes massive is the main natural stone sources in Çal, Bekilli and Baklan Triangle in the northeast of the City. The aim of this s...

Bu çalışmada karar ağacı derinliklerinin CART algoritmasının kestirim kapasitesine etkisinin incelenmesi amaçlanmıştır. Ayrıca, kaya mühendisliğinde karar ağaçlarının kestirim amaçlı kullanılabilirliği araştırılmıştır. Çalışmanın amacına uygun olarak bir tünel açma makinesinin ilerleme performansı verileri kullanılmıştır. Yapılan değerlendirme sonu...

Traditionally, some regression techniques have been used for prediction of some rock properties using their physical and index parameters. For this purpose, numerous models and empirical equations have been proposed in the literature to predict the uniaxial compressive strength (UCS) and the elasticity modules (E) of intact rocks. Two of the powerf...

Geomechanical properties of natural stones have a crucial importance when stones are used for constructing modern structures and buildings. Therefore, field and laboratory studies are indispensable to investigate the stone quality for purposed structure. Denizli and Antalya surroundings in South-western Turkey have large natural stone reserves and...

Brittleness is one of the most crucial rock features for underground excavation and design considerations in rock mass. Direct standard testing method for measuring rock brittleness, the combination of rock properties rather than only one rock parameter have not available yet. Therefore, it is indirectly calculated as a function of some rock proper...

Geological factors including the orientation, condition and frequency of discontinuities in rock mass, and also intact rock properties such as strength and brittleness are crucial parameters for performance analysis of hard rock TBMs. These data along with machine specifications such as thrust and power allow the appraisal and prediction of machine...

Predicting tunnel boring machine (TBM) performance is a crucial issue for the accomplishment of a mechanical tunnel project, excavating via full face tunneling machine. Many models and equations have previously been introduced to estimate TBM performance based on properties of both rock and machine employing various statistical analysis techniques....

The Schmidt hammer test is a non-destructive method which can be used in both laboratory and field to provide a quick and relatively inexpensive measure of rock hardness. The study investigated the relationship between the Schmidt hardness and modulus of elasticity, uniaxial compressive strength and index properties of nine types of rock including...

Brittleness fracturing of rock is one of the most popular research areas in rock engineering, since some rocks show brittle fractures under loads. Direct standard testing method for measuring rock brittleness have not available yet. Therefore, rock brittleness is indirectly obtained as a function of rock strength. The aim of this study is not only...

The standard penetration test (SPT) is the in situ test most commonly used to investigate the properties of silt, clay, sand and fine gravel. The Menard pressuremeter test (PMT) can be utilized to obtain the strength and deformation properties of any soil or weak rock. The study investigated the relationship between the corrected SPT blow count (N...

The key parameters on the estimation of tunnel-boring machine (TBM) performance are rock strength, toughness, discontinuity in rock mass, type of TBM and its specifications. The aim of this study is to both assess the influence of rock mass properties on TBM performance and construct a new empirical equation for estimation of the TBM performance. T...