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

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Rock Mechanics and Rock Engineering
Authors:
Javier Macias at JMConsulting-Rock Engineering AS
Javier Macias
  • JMConsulting-Rock Engineering AS
Filip Dahl at SINTEF
Filip Dahl
Amund Bruland at Norwegian University of Science and Technology
Amund Bruland
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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.
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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.
... The results obtained from the small-scale linear rock cutting test are very similar to those obtained from the full-scale test, proving that the small-scale test can be used to guide the design and selection of TBMs. In contrast to the small-scale linear test, Macias et al. 22 developed the Rolling Indentation Abrasion Test method (RIAT) to evaluate the cutter life. Based on the idea of RIAT, Zhao et al. 23 and Yang et al. 24 investigated the effects of joint spacing and joint angle on the cutting performance. ...
Research on the rock cutting performance and feasibility verification of small-scale rotary cutting test for disc cutter
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Small-scale rock cutting tests serve as a simple approach to evaluate the performance of tunnel boring machines (TBMs), but the feasibility of this method requires further investigation. Herein, a small-scale rotary cutting machine is developed to conduct rock cutting tests, and the cutting performance is investigated. The results indicate that similar cutting performance can be achieved through both small-scale and full-scale tests. The critical penetration depth for effective rock cutting by the cutter is 0.5 mm, below which the cutter grinds against the rock. The optimal ratio of cutting spacing to penetration depth obtained in small-scale tests is 4.47. A result within the empirical range can be achieved by multiplying the optimal small-scale cutting parameters with the scale coefficient, demonstrating the feasibility of using small-scale tests to guide the design of cutter heads. Based on the test result, the scale prediction model is constructed to predict the full-scale cutting force. The predictive capability of the proposed model and CSM model is validated using 72 sets of full-scale test data involving the same types of rock, and the predictions of the proposed model are closer to the test data.
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... In hard, coarse grained crystalline rocks the groove is sometimes poorly developed, irregular or almost invisible ( Fig. d-g). This may be attributed to the skating effect (Al-Ameen and Waller 1994, Macias et al., 2016) known to occur in these types of rocks (Fig. 2h). Whenever possible the Sw is measured in the last 25 % of the scratch groove where pin tip wear is already close to the final CAI. ...
Towards a Rapid and Practical Determination of the Pin-rock Interaction Parameters of the CERCHAR Abrasivity Test
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The CERCHAR test is a widely used index test for evaluating rock abrasiveness and associated tool wear in rock excavation. However, routine testing only assesses the wear on the pin itself. To evaluate the advancement rates in rock cutting during excavation, it is also crucial to consider the material removal of the rock. Recent studies have begun to include this aspect by developing advanced methods, automated testing devices, or using customized equipment for test evaluation. However, these methods are too time-consuming and specialized to be used in routine laboratory testing. This study investigates the correlation between traditional CAI and associated material removal by complementary measurements of the scratch groove on the rock specimen using a stereomicroscope. The presented approach enables the straight forward determination of additional parameters, such as rock volume removal and pin tip loss, based on the inherent pin tip geometry and associated scratch groove geometry. These parameters are then used to calculate the CERCHAR Abrasion Ratio, which serves as a proxy for the excavability of different rock types. Despite some minor limitations, this approach can deliver values that are comparable to those obtained using specialized equipment. Therefore, it has the potential to be a practical method for assessing abrasion and excavation on job sites.
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... Cutter consumption rate (CCR) is one of the main parameters affecting the total cost of mining and tunneling projects excavated by mechanical excavators. One of the critical parameters affecting the wear of cutters is the abrasivity of the rocks, which can be estimated in different laboratory test methods (LCPC 1990;Nilsen et al. 2006;Labaš et al. 2012;Alber et al. 2014;Macias et al. 2016). The Cerchar abrasivity index (CAI) test is a well-known and widely used test method for determining the abrasivity of rocks with a simple test procedure. ...
Effects of changing water content of clay-content rocks on field cutter consumption rate of roadheaders: a case study of porous ignimbrites
Article
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  • B ENG GEOL ENVIRON
The changing formation characteristics during excavation can cause a higher cutter consumption rate (CCR) of mechanical excavators than theoretically estimated before the project begins. This study investigates the adhesive potential of clay-content porous ignimbrites in increasing water content and their effects on the CCR of roadheaders. For this purpose, the actual field CCR data of roadheaders were recorded for ten cold storage caverns (CSC) projects during the excavation in dry and wet conditions. Then, laboratory tests were carried out on the rock samples collected from project areas. CCRs of roadheaders were theoretically estimated based on the Cerchar abrasivity index of rocks using three different empirical models. The laboratory test results showed that increasing water content reduces the abrasivity and strength of the rocks. The theoretically estimated results also showed that CCR is to be less under saturated conditions. However, actual field data revealed higher CCRs for all CSC projects in wet conditions. Therefore, the adhesion potential of rocks in different water contents was analyzed, and positive relationships were obtained between the field CCR in wet conditions and the adhesion potentials of excavated rocks with 15%, 20%, and 25% water content. New equations were developed to estimate the CCR of roadheaders, especially in excavating rocks that have an adhesive potential to cutters, such as clay-content rocks. It has been concluded that for an accurate CCR estimation, more than theoretical calculations will be required, and changing formation conditions should also be analyzed in detail.
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... Therefore, it has been widely and increasingly employed in the hydraulic engineering, mineral engineering and traffic engineering worldwide (Acaroglu et al., 2008;Liu et al., 2017). The cutting efficiency of TBM is significantly affected by the geo-mechanical and geological condition of a construction site, such as the uniaxial compressive strength (UCS) of rocks, the orientation, spacing and strength of rock joints, the rock mass quality for TBM (Q TBM ), etc. (Barton, 2000;Mohammadi et al., 2015;Macias et al., 2016;Li et al., 2020;Song et al., 2022). Particularly, the shear strength of rock joints plays an important role in the deformation and cracking process of rock masses, which determine the rock breakage mode and penetration rate of TBMs . ...
Disc-cutter induced rock breakage mechanism for TBM excavation in rock masses with different joint shear strengths
Article
Full-text available
  • Apr 2024
When tunnel boring machines (TBMs) excavate through jointed rock masses, the cutting efficiency is strongly affected by the shear strength of joints, the mechanism of which, however, remains poorly understood. In this study, a series of disc-cutter indentation tests were conducted on granite rock mass specimens with different joint shear strengths. During the indentation, the cracking process was recorded by a digital image correlation (DIC) system. The deformation and strength of specimens, cracking behavior, rock breakage mode and cutting efficiency were quantitatively investigated. In addition, to investigate the combined effects of joint shear strength, orientation and spacing on the rock breakage mechanism, numerical rock mass models were established based on a particle flow code PFC2D. Experimental results reveal that the cracking of primary and secondary cracks changes from the mixed shear-tensile to tensile mode in the initial stage, while the joint shear strength does not affect the cracking mode in the subsequent propagation process. The rock breakage mode is classified to an internal block breakage mode, a cross-joint breakage mode and a cutters-dependent breakage mode. The cross-joint breakage mode is optimal for improving the cutting efficiency. Numerical simulation results reveal that the increase in the joint shear strength changes the internal block breakage mode to cross-joint breakage mode for rock masses of particular ranges of joint orientation and spacing. These findings provide basis for improving the TBM cutting efficiency through jointed rock masses.
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Effects of Blade Speed on Microstructure and Wear Behavior in the Abrasion Value Cutter Steel (AVS) Test
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Cutter wear is a critical concern in TBM tunneling, directly influencing cutter consumption and tunnel advance rate-crucial aspects for project planning and risk management. This laboratory study investigates the impact of the cutter rotational speed on wear behavior and lifespan using the Abrasion Value of Steel (AVS) test. The study employed a quartzite sandstone sample with a Cerchar Abrasivity Index (CAI) of 3.14 and H13 steel sample with 648 Vickers hardness for the AVS test. In the Experimental Design, five rotational speeds of 10, 15, 20, 25, and 30 RPMs were employed and their impacts were explored. Results revealed a 147.4% increase in AVS (mg) as rotational speed increased. Concurrently, quartzite sandstone abrasiveness escalated from “very abrasive” to “extremely abrasive,” while cutter life transitioned from “very low” to “extremely low”. Also, a direct linear relationship with a strong correlation between rotational speed and AVS was observed. Moreover, increasing rotational speed led to a 29% decline in the cutter life index (CLI), indicating a strong linear correlation. The study of the width of the cutter surface wear profile exhibited a relationship with angular velocities with a strong coefficient determination, increased by 27.5%. In the analysis of the disc cutter’s microstructure through a Scanning Electron Microscope (SEM), martensite as the predominant steel structure was identified. Spectroscopic analysis using Energy Dispersive Spectroscopy (EDS) revealed hard phases, including vanadium deposits and carbides. These findings contribute valuable insights into the intricate relationship between cutter rotational speeds, wear characteristics, and lifespans.
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Dynamic reliability evaluation of TBM components in tunnel construction
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The complex geological conditions in tunnels pose a huge challenge to the reliability of tunnel boring machine (TBM). However, existing reliability studies typically focus on core structures such as cutters and cutterheads, with less consideration given to the rest of the components that frequently fail. In this study, the reliability analysis and dynamic evaluation of TBM components with high failure rates are carried out relying on the Shanxi Central Yellow River Diversion Project. The life distribution and reliability variation characteristics of TBM components under different rock mass classes are investigated in terms of tunnelling time and tunnelling distance as two types of life data indexes. And the life index which is more suitable for the reliability evaluation of TBM components is identified by comparison. On this basis, a dynamic evaluation method for the reliability of TBM components under the condition of multi‐classes surrounding rock is proposed. This method can quickly evaluate the current reliability of TBM components and serve as the basis for preventive maintenance. The results of this study play a certain role in supplementing the reliability research of TBM and also provide a scientific basis for optimizing the design and maintenance strategy of TBM components.
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Study of Cerchar abrasive parameters of monomineralic rocks and its application for evaluating cutting efficiency
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The Cerchar test is the most commonly used method for evaluating rock abrasivity and estimating tool wear. The conventional test results are reported based on the measured changes of the wear parts, and little attention is paid to what happens on the rock surface and scratching force. Since the cutting process is the interactive behavior between cutting tools and rock materials, the changes in both parts are important to represent rock-tool interaction and evaluate cutting efficiency. In the present study, the Cerchar tests have been carried out on eleven types of monomineralic rocks by using an improved West apparatus. The related abrasive parameters have been comprehensively and systematically analyzed, including stylus tip wear, rock material loss, applied horizontal force, and scratching energy. The variation characteristics of those abrasive parameters have been studied. The specific abrasivity ratio (SAR) and scratching specific energy (SSE), which represent the tool wear and energy consumption per unit of rock removal respectively, have been developed to evaluate the cutting efficiency of different rocks. The results show that the SAR and SSE values of the tested rocks have comparable data ranges and variation trends due to the same mathematical treatment of the indices. Under the given rock removal volume, the SAR and SSE could be used to compare and classify the relative cutting efficiency of different rocks. The lower the SAR and SSE values, the less stylus wear and lower energy consumption in the cutting process, indicating higher cutting efficiency. According to their values, the cutting efficiency of the tested rocks is divided into four categories: high cutting efficiency, medium cutting efficiency, low cutting efficiency, and very low cutting efficiency. The SAR-based and SSE-based classifications are consistent for most of the tested rocks, and the SAR-based classification is lower to higher abrasive rocks (pyroxene, hematite, and quartz) due to it considering the influence of stylus tip wear. Hence the SAR-based classification is more suitable for hard and highly abrasive rocks.
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DEVELOPMENT OF A FORCE ESTIMATION MODEL FOR ROCK FRAGMENTATION WITH DISC CUTTERS THROUGH THEORETICAL MODELING AND PHYSICAL MEASUREMENT OF CRUSHED ZONE PRESSURE
Thesis
Full-text available
  • May 1997
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.
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