ArticlePublisher preview available

New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and in order to evaluate the newly developed RIAT test method, a comprehensive laboratory testing program including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.
This content is subject to copyright. Terms and conditions apply.
ORIGINAL PAPER
New Rock Abrasivity Test Method for Tool Life Assessments
on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion
Test (RIAT)
F. J. Macias
1
F. Dahl
2
A. Bruland
1
Received: 18 June 2015 / Accepted: 20 September 2015 / Published online: 6 October 2015
Springer-Verlag Wien 2015
Abstract The tunnel boring machine (TBM) method has
become widely used and is currently an important presence
within the tunnelling industry. Large investments and high
geological risk are involved using TBMs, and disc cutter
consumption has a great influence on performance and
cost, especially in hard rock conditions. Furthermore,
reliable cutter life assessments facilitate the control of risk
as well as avoiding delays and budget overruns. Since
abrasive wear is the most common process affecting cutter
consumption, good laboratory tests for rock abrasivity
assessments are needed. A new abrasivity test method by
rolling disc named Rolling Indentation Abrasion Test
(RIAT) has been developed. The goal of the new test
design and procedure is to reproduce wear behaviour on
hard rock tunnel boring in a more realistic way than the
traditionally used methods. Wear by rolling contact on
intact rock samples is introduced and several rock types,
covering a wide rock abrasiveness range, have been tested
by RIAT. The RIAT procedure indicates a great ability of
the testing method to assess abrasive wear on rolling discs.
In addition and to evaluate the newly developed RIAT test
method, a comprehensive laboratory testing programme
including the most commonly used abrasivity test methods
and the mineral composition were carried out. Relation-
ships between the achieved results from conventional
testing and RIAT results have been analysed.
Keywords Hard rock tunnel boring Rock abrasiveness
Cutter wear assessments Rock abrasivity test method,
Rolling Indentation Abrasion Test (RIAT)
1 Introduction
1.1 General
Cutter consumption plays a significant role in performance
and cost during tunnel boring. Reliable assessments of
cutter consumption are needed for planning and risk
management, especially in hard rock conditions.
Many factors are influencing the number of cutters
consumed in hard rock Tunnel Boring Machines (TBMs).
Normal TBM operation results mainly in abrasive wear of
the cutter rings, which has been verified to be proportional
to cutter rolling distance by several researches (Rostami
1997; Bruland 1998; Frenzel et al. 2008).
There are some accepted and commonly used test
methods for estimation of rock abrasiveness, Cerchar test
(Valantin 1974), Laboratorie Central des Ponts et Chaus-
se
´es (LCPC) test (Normalisation Franc¸aise P18-579 1990)
and the Abrasion Value Steel (AVS) test method (Dahl
et al. 2012) In addition, some researches have been
developing studies to classify rock abrasiveness in the last
decade (Plinninger and Restner 2008; Thuro and Ka
¨sling
2009; Dahl et al. 2012). Plinninger and Restner (2008) give
an overview of some of the most representative testing
methods and classification of the results. Thuro and Ka
¨sl-
ing (2009) performed a comparative study using three
methods for abrasivity assessments introducing a classifi-
cation of abrasiveness for soil and rock. Dahl et al. (2012)
presented classifications of the Norwegian University of
Science and Technology (NTNU)/SINTEF drillability test
&F. J. Macias
javier.macias@ntnu.no; fjmaciasr@gmail.com
1
Department of Civil and Transport Engineering, Faculty of
Engineering Science and Technology, NTNU,
7491 Trondheim, Norway
2
SINTEF, Building and Infrastructure, Rock and Soil
Engineering, Trondheim, Norway
123
Rock Mech Rock Eng (2016) 49:1679–1693
DOI 10.1007/s00603-015-0854-3
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Tunnel Boring Machines (TBMs) are widely used in tunnel construction, and the tunnelling mainly depends upon the rock breaking of TBM cutters. In the process of TBM tunnelling, cutters move on the rock surface in a rolling and sliding motion while under the action of a thrust force, causing rock fracture and removal and cutter wear [1,2]. The TBM advance rate and cost is closely related to the rock breaking efficiency and the wear resistance of cutters. ...
... For a TBM cutter, the cutter ring is a key component to break rock mass and it directly acts on the rock surface under the action of thrust force. In the process of tunnelling, the thrust force is up to 21,000 kN [10], and the ring suffers heavy-load-impact and abrasive wear [1,2]. The high thrust force and the high hardness and strong abrasiveness of the rock are recognised to be responsible for the serious wear of TBM cutters and the low rock breaking efficiency. ...
Article
Full-text available
The purpose of this study is to achieve better understanding of associated mechanisms and to recommend and identify new strategies to develop new rock breaking technology for Tunnel Boring Machines (TBMs). Tunnel Boring Machine tunnelling mainly depends upon the rock breakage caused by cutters moving on a rock surface in a rolling and sliding motion while under the action of thrust force. The rock breaking behaviour is controlled by the mechanical interaction between the cutters and the rock. Due to the high hardness and high abrasiveness of rock, the cutters have to work under very high thrust force and suffer heavy-load-impact and abrasive wear, causing serious wear and low rock breaking efficiency. Rock-boring organisms exist in nature, which achieve drilling and/or tunnelling in rocks through a tribochemical interaction. This phenomenon is called bioerosion and the organisms are natural ‘TBMs’ to some degree. In this study, the interaction between TBM cutters and rock is presented, and current measures to improve cutter wear and rock breaking efficiency and their limitations are reported. Then, the connotation, mechanism and typical cases of bioerosion are presented. Finally, inspired by bioerosion, a new chemically assisted rock breaking technology is proposed for TBMs. © 2021 The Authors. Biosurface and Biotribology published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology and Southwest Jiaotong University.
... Empirical and semiempirical models have been provided by previous authors [10][11][12][13][14][15][16][17][18] to predict the cutter wear of TBMs. They consider rock parameters (CAI, UCS, quartz content, Vicker's hardness number (VHNR), fracturing degree, porosity, drilling rate index, and rock mass classification), machine properties (thrust, torque, penetration rate, rpm, and TBM diameter), and cutter geometry to estimate cutter tool life. ...
Article
Full-text available
An earth pressure balance (EPB) TBM is used in soft ground conditions, and these conditions lead to the fluctuation and instability of machine parameters. Machine parameters influence cutter wear and tunnel excavation. For this reason, to evaluate and predict the cutter wear of an EPB TBM, a 1D CNN model was used to provide machine-parameter-based cutter wear prediction using an EPB TBM operational dataset. The machine parameters were split into 80% training and 20% test datasets. Compared to traditional machine learning applications and two deep neural network models, the proposed model provided reliable results with a reasonable computational time. The correlation coefficient was 89.6% , the mean squared error (MSE) was 57.6, the mean absolute error (MAE) was 1.6, and the computational wall time was 3 min 22 s.
... To simulate the rock-breaking process of cutters more accurate, several test methods for rolling indentations have been used for rock-rolling penetration recently. For instance, Macias et al. (2016) employed the rolling indentation abrasion test (RIAT) method to penetrate the surface of an intact rock sample. Yang et al. (2018) completed two groups of the rock rolling boring experiment to explore the effect of joint orientation and spacing, respectively. ...
Article
Full-text available
Cutter spacing is one of the important mechanical parameters that influence the cutting efficiency of tunnel boring machines (TBMs). A methodology was developed to optimize the cutter-spacing for efficient mechanical breaking, which improves the cutting efficiency of the jointed rock mass. In the beginning, 18 indentation tests were carried out on jointed granite specimens by varying cutter spacing, joint spacing, and joint set orientation, respectively. The cracking process of the jointed rock mass was captured by using a digital imaging correlation system clubbed with high-speed photography in real-time. Experimental results indicate that the joint plane facilitates horizontal displacement of the jointed rock mass, which causes more shear cracks develop across the joints. As a result, the efficiency of mechanical rock breaking of jointed rock mass becomes increases. Subsequently, a new term called crack propagation specific energy was proposed to determine the optimal cutter spacing, referring to the consumed energy per unit crack length. The optimal cutter spacing can be obtained from the limited experimental data based on crack propagation specific energy. It was found that the optimal ratio of cutter spacing to penetration depth s/p is 10. In addition, the horizontal displacement of jointed rock mass under the disc cutter favors the development of shear cracks, causing the increase of the optimal cutting spacing. The present investigation provides insights into the cutter design in jointed rock mass conditions, thereby making it possible for designers to adjust their design to enhance the TBM cutting efficiency. Highlights • Propose the specific energy of crack growth to determine the best cutter spacing. • The joint plane facilitates horizontal displacement of the jointed rock mass. • More shear cracks appear at the joints of jointed rocks. • The optimal ratio of cutter spacing to penetration depth is determined.
... For example, on the basic of Cerchar test, Michalakopoulos et al. [25] investigated the effect of steel hardness on Cerchar Abrasivity Index (CAI), which represents the abrasiveness of rocks. Afterwards, Macias et al. [26] developed a novel test named Rolling Indentation Abrasion Test (RIAT) to simulate the cutter wear process in a realistic way. In this study, the influences of rock types, CAI, Abrasion Value cutter Steel (AVS), and mineral compositions on wear loss were investigated. ...
Article
Full-text available
Argillization is a process in which clay-bearing rocks disintegrate into the clay under the action of high temperature, pressure, and water. When tunnel boring machines (TBMs) excavate in the mudstone, argillization takes place, causing the clogging of the TBM cutterhead. As a result, the penetration rate drops gradually. Abnormal wear might occur. To investigate the evolution of argillization of mudstone and cutter wear during the TBM tunnelling, a series of rotary indentation tests were carried out on the self-designed experimental bench for different loading times. During the test, the temperature and penetration depth of disc cutters were measured in real time. After loading, microstructures of cutting grooves, slacking mudstone, and worn cutter ring were observed by stereomicroscope. Consequently, the evolution of argillization in mudstone and cutter wear were investigated. Experimental results indicate that the argillization process of mudstone by disc cutter can be divided into three stages: mechanical cutting stage, deterioration of mudstone and the formation of slacking mudstone stage, and adherence of slacking mudstone stage. Specifically, at mechanical cutting stage, the rock was cut by cutter directly, causing high frictional heat. Then the microstructure of mudstone was deteriorated due to the water-weakening mechanisms, temperature effect, and mechanical activation effect. Finally, the slacking mudstone was adhered to the disc cutter. Correspondingly, due to the argillization of mudstone, the disc cutter wear goes through the mechanical wear stage, argillization wear stage, and secondary wear stage in sequence. This investigation reveals the rock cutting mechanism of TBM considering the argillization of mudstone. Furthermore, it provides some references for design and operation of the TBM.
Article
Full-text available
Understanding the force state of disc cutters in advance is of great practical significance to predict the dynamic response during mechanical excavation and provide data information for design and arrangement of cutterhead. The sandstone-breaking behaviour of single disc cutter is studied based on the three-dimensional Particle Flow Code (PFC3D) software and rock rotational cutting tests. A novel platform of rotational cutting, which enables circular cutting up to 3.3 m in diameter, is developed to compensate for the shortcoming of existing platforms. The five mechanical and structural parameters (penetration depth, rotational speed, tip width, cutter spacing and installation radius) are changed to investigate the characteristics of cutting force. The numerical simulation reveals that the cutter ring breakage is not only attributed to normal impact, but also caused by side force, which decreases with the growth of installation radius. Meanwhile, the average cutting force and the number of bond breakages increase with the growth of penetration depth and tip width due to the increasing contact area between rocks and disc cutters. It is found that the optimum cutter spacing is 100 mm based on the variation of specific cutting energy. The rotational speed has a weak effect on the cutting force. The trend of average cutting force obtained from the experiment is similar to that of numerical results, and the maximum error does not exceed 15% by comparing the both results. This verifies the accuracy of numerical results.
Article
Using tunnel boring machines to excavate high-strength intact rock masses is becoming more common. Due to the interactions between disc cutters and rocks, abnormal wear of disc cutters, especially cutter chipping, has become a common phenomenon. Existing research has mainly focused on normal wear of disc cutters without addressing abnormal wear cases. This study used the disc cutter consumption data of a tunnel project in China to investigate the abovementioned problem based on field research. According to the failure patterns and fracture surface characteristics, the cutter chipping patterns were mainly categorized into four types: granule chipping, patch chipping, primary collapse, and secondary collapse. To further simulate the evolution of disc cutter chipping, based on the linear plastic bond model, a new contact model called the modified plastic bond (MPB) model was proposed to solve the metal simulation problem in Particle Flow Code software. To this end, a set of uniaxial tensile and compressive tests were initially conducted to verify the applicability of the MPB model. Then, a series of three-dimensional rock-cutting simulation tests were conducted to reflect the evolutionary processes involved in each type of cutter chipping. The cutter chipping mechanism and morphological characteristics were classified and summarized in detail. The results revealed that the cutting speed and penetration growth led to a rising trend in the probability and intensity of the cutter chipping. The presence of initial defects also induced an adverse effect on the service life of the cutter. The results indicated suitable working conditions for the cutter and suggested ways to control tunneling parameters and avoid frequent cutter chipping cases.
Article
This paper aims to discuss the recent development in rock hardness testing methods and their applications in rock engineering and geological studies. Hardness is one of the essential physical characteristics of minerals and rocks, with dominant effects on rock mechanics and excavatability. In this paper, all available rock hardness testing methods are classified into main categories: static and dynamic methods. After that, standards and testing procedures have been briefly discussed using various literature. The review clarifies the dominant factors that affect the rock hardness as well as physicomechanical characteristics, which affect the hardness. The correlations between different hardness testing methods are analyzed using regression analysis, and their interconnections between them are presented. Also, the applications of hardness scales in the assessment of rock excavatability and machinability have been investigated. In total, it could be concluded that dynamic hardness testing methods have been widely applied in rock engineering. However, the relative standards and field measurement procedures have not been developed well. Future research must incredibly be focused on this lack of past studies and should try to develop reliable models for the prediction of physicomechanical rock parameters.
Article
The LCPC method is one of the most common abrasion tests used for determining soil and rock abrasivity. LCPC abrasivity coefficient (LAC) and LCPC brittleness coefficient (LBC) are two parameters obtained from this method. The rotation speed (RS) and rotation time (RT) are two factors that affect the results of this experiment. In this paper, the effect of these two factors on quartz and feldspar minerals is investigated innovatively. The tests were carried out in two groups. In the first group tests, the RS was changed from 500 to 4500 rpm, and LAC and LBC were measured at RTs of 1, 2, 3, 4, and 5 min. The results showed that LAC and LBC increase nonlinearly with increasing RS and RT, and the relationship of LAC and LBC with RS and RT is affected by the mineralogy. Experimental relationships between LAC and RT with a coefficient of determination greater than 0.97 were proposed for quartz and feldspar. Study of two-dimensional images of grains showed that the impact of coarse grains on the wear of the impeller is more than that of fine grains. In the second series, the sample inside the container is replaced with a new sample each minute at different RS values. The results showed that by increasing RT, the LAC rate increased as well. Besides, the LAC increased linearly with increasing RT due to the effect of the grain size and shape changes, which were removed during the test. In addition, the effect of the RS on the LAC is greater than that of the RT. Comparing the result of these two series, the optimum rotation time (ORT) is defined as the time when the trend line in the LAC-RT graph changes from linear to logarithmic. This parameter indicates the moment at which the effect of grain shape and size on impeller wear starts to decline. The changes in ORT versus RS for quartz and feldspar are similar and exponential.
Article
Understanding the drillability indices of thermal granite under various water-cooling conditions is of great significance for deep drilling and wellbore stability during the extraction of deep geothermal energy. In this paper, we report the results of micro-drilling tests, indentation hardness tests, friction-and-wear tests as well as conventional physico–mechanical tests on thermal granite after water-cooling treatment, and the relationships between mechanical strength and drilling parameters of granite are discussed based on statistical analysis. In addition, the micro-characteristics of thermal and water-cooling defects in granite were observed via scanning electron microscopy. With increase in thermal temperature, the conventional physico–mechanical parameters and indentation hardness of thermal granite after water-cooling decreased linearly, while the average values of drilling rate, plasticity coefficient, and the mass losses of granite specimens and the grinder increased exponentially. The average P-wave velocity, uniaxial compressive strength, tensile strength and indentation hardness decreased by 84.9, 66.2, 73.3 and 66.1%, respectively, when the granite was heated to 600 °C. At 600 °C, the wellbore wall of granite collapsed during the micro-drilling tests and the friction-and-wear tests, and the average width and density of micro-cracks of thermal granite increased to 20.54 μm and 4.82 mm/mm2. The average width and density of micro-cracks in thermal granite under various water-cooling conditions developed gradually with thermal temperature, which was the main reason for the degradation in the drillability indices of granite. Strong links exist between the mechanical strength and drilling parameters of granite after water-cooling, and the drilling parameters of thermal granite can be estimated by the use of mechanical strength with given empirical equations. This study provides a theoretical basis for the geothermally accurate simulation and engineering of wellbore stability for deep hot dry rock drilling.
Thesis
Full-text available
Accurate and reliable estimation of cutting forces acting on a disc cutter is a prerequisite in developing models for design optimization and performance prediction of Tunnel Boring Machines (TBM). The ability to accurately predict TBM performance means more reliable estimates of project completion time and costs, hence improved confidence in the application of this technology to a wider sector of the underground construction market. The disc cutting forces are generated and controlled by the load distribution within the contact area between the rock and the cutter. To determine the magnitude and location of load distribution, a series of laboratory cutting tests were designed and performed to measure the strain and stresses within the cutter ring. The measurements were obtained by installing a set of strain gages on each side of the disc ring very close to the tip. The experimental program started by first installing the ring on the hub and measuring the strains caused by the hoop stresses to estimate the pressure between the ring and the hub. A special data reduction program was developed to analyze the gage outputs to determine the load distribution in the contact area. In addition, extensive theoretical and Finite Element Modeling of the disc ring were performed for comparison with experimental observations. The ability of the gages and the data reduction program to accurately measure the loads was verified by running the disc on a steel plate. The actual test program included cutting three rock types, Indiana Limestone, Colorado Red Granite, and Umettela basalt, to develop cutting force and strain measurement data under conditions of soft to hard, brittle rocks. The results of the test program concluded that the commonly accepted notion of cutter ring being loaded over the full length of the contact area is not correct. The analysis of data obtained showed that the loading area is a portion (30-80%) of the contact area, close the center of the arc of contact. The width of the loading area was found to increase with the depth of cutter penetration in softer rocks while in the harder rocks, the extent of loading area was relatively insensitive to changes in penetration. Further, test observations and analysis of the loading area led to the conclusion that the rock failure primarily occurs in front of the cutter. The force estimation equations were developed by regression analysis of an extensive data base of cutting forces using disc cutters in different rock types. These equations were then incorporated into a model designed to predict and optimize TBM performance as a function of rock properties and machine capabilities. The model allows input of any cutter geometry and layout with the capability to produce overall project completion time and schedules. To check the accuracy of the developed model, field performance data from four different tunneling projects were analyzed and compared with model outputs. Overall, a very good correlation was obtained between the model predictions and the field performance of the TBMs.
Article
Full-text available
A new approach to rock and soil abrasivity testing is presented focusing on the needs of underground excavation. The abrasivity assessment is based on the LCPC Abrasivity Test which was developed by the Laboratoire Central des Ponts et Chaussées in the 1980ies. The LCPC Abrasivity Coefficient (A BR or LAC) can be used as a measure for both the abrasivity of the material and the influence of the grain size. A calibration chart has been established using different artificial and natural granular materials, containing both rounded and angular grains, different rock materials and especially highly abrasive material such as quartz and non abrasive material such as limestone. This chart allows the classification of different materials using the background of tool wear and drillability problems. Applied in the correct framework of geological and geotechnical investigations, the LCPC test allows a reliable, quick and hence, cost effective assessment of the abrasivity of rock and granular materials.
Article
Full-text available
Article
Depending on rock excavatability and rock abrasivity disc cutters can exhibit significant wear. Detailed data on 7 tunneling projects comprising a total length of more than 127 km and more than 12,000 replaced disc cutters have been collected in a custom-made data base. A detailed analysis has been carried out to characterize failure modes and wear patterns of disc cutters. A prediction model has been established that includes cutter life and cutter costs.
Article
This book covers the fundamentals of tunneling machine technology: drilling, tunneling, waste removal and securing. It treats methods of rock classification for the machinery concerned as well as legal issues, using numerous example projects to reflect the state of technology, as well as problematic cases and solutions. The work is structured such that readers are led from the basics via the main functional elements of tunneling machinery to the different types of machine, together with their areas of application and equipment. The result is an overview of current developments. Close cooperation among the authors involved has created a book of equal interest to experienced tunnelers and newcomers. © 2008 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH und Co.KG, Berlin.
Article
Starting with a survey of the main features of rock disintegration by mechanical tools and the limiting conditions of this process, this paper attempts to find simple, practice-oriented methods to assess penetration, performance and cutter consumption. Using data from 4 TBM-operations with machines of very similar characteristics some additional rock parameters have been investigated to find out, whether they have significant influence. -English summary