1. IDOWU OLUWABUNMI ITIOLA PROFESSOR DANIELE PEILA
Post Graduated Master Course in TUNNELLING AND TUNNEL BORING MACHINES
SOIL AND ROCK TESTS ABRASIVITY IN MECHANIZED TUNNELING
IDOWU OLUWABUNMI ITIOLA
(STUDENT ID: S210674)
PROFESSOR DANIELE PEILA
DIATI- Politecnico di Torino
Endorsed by
22 Slides
With the support of
December 2014

2. Test Methods For Rock Abrasiveness In Tunneling
CONTENTS
Introduction
Test Methods For Rock Abrasiveness In Tunneling
Test Methods For Soil Abrasiveness In Tunneling
Objectives of the Study
Materials and Methods
Results and Discussion
Conclusion and Recommendation
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3. INTRODUCTION
Tunnel boring machines (TBM) has been the successful key to excavation in hard rock and soft-ground tunneling for several decades with a great deal of extinction in various projects, and distinctive examination of rock mass characterization through developed test methods (Moh hardness, NTNU, CSM, SAT, LCPC and Politecnico di Torino tests) that gives a preliminary estimation of conditions that are likely to be encountered during tunnel excavation. This study focus on determining the wear impact of Quartz sand abrasiveness on Tunneling Boring Machines (TBM) disc cutter.
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4. Test Methods for Rock Abrasiveness in Tunneling For rocks several methods for estimating abrasiveness exist already. The most commonly used are (Ozdemir & Nilsen, 1999 and Büchi et al. 1995): 1. Moh hardness test: Cutter life can be estimated from the relative percentage of minerals of different Moh’s hardness classes (>7, 6, 4-5 and <4). For coarse grained rock and soil this is most commonly determined by petrographic analysis in microscope. For fine grained rock and soil it is most commonly determined by X-ray diffraction (XRD), sometimes supplemented by differential thermal analysis (DTA). 2. The Vickers test: The hardness number is defined as the ratio of the load applied to the indenter (gram or kilogram force) divided by the contact area of the impression (square millimeters). The Vickers indenter is a square based diamond pyramid with a 130° included angle between opposite faces.
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5. 3. The Cerchar test, giving the Cerchar Abrasivity Index (CAI) : The Cerchar test is performed by scratching a freshly broken rock surface with a sharp pin of heat-treated alloy steel. The Cerchar Abrasivity Index (CAI) is then calculated as the average diameter of the abraded tip of the steel pin in tenths of mm after 1 cm of travel across the rock surface. The advantage of this test is that it can be performed on irregular rock samples. The CAI values vary between less than 0.5 for soft rocks such as shale and limestone to more than 5.0 for hard rocks such as quartzite. 4. The LCPC abrasimeter test : The LCPC abrasimeter test was developed in France to test the “abrasivity” and “breakablity” of granular material such as crushed rock or synthetically created materials (Büchi et al. 1995). Layout of the test apparatus and the procedure of the LCPC test are described in the French Code P This value varies between 0 and over 2000 depending on rock abrasiveness.
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6. Drilling Rate Index, DRI The Brittleness Test
5. The NTNU abrasion test :This test is also known as SINTEF method and is considered as one of the most recognized and widely used methods for Tunnel Boring Machine (TBM) performance prediction Abrasion testing of crushed rock particles <1.0 mm. The Abrasion Values AV/AVS represent time dependent abrasion of tungsten carbide/cutter steel caused by crushed rock powder. NTNU/SINTEF method consists of a set of laboratory tests and different indices which are described herein:
Drilling Rate Index, DRI
The Brittleness Test
The Sievers’ Mimiature Drill Test
Cutter Life Index, CLI
The Abrasion Value Steel (AVS)
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7. LCPC test apparatus. 1) Motor, 2) Rotating impeller, 3) Jar containing the abrasive, 4) Funnel tube.  
A- Cerchar apparatus B- West apparatus C- CSM apparatus
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8. Test Methods on Soil Abrasiveness in Tunneling
For soils, few test methods are available to describe the abrasive characteristic of soils. The soil testing methods are:
1. The New NTNU Soil Abrasion Test (SAT): The new NTNU Soil Abrasion Test (SAT) is a further development of the existing abrasion tests for rock. Compared with the AVS test only one detail has been changed; instead of crushed rock powder <1 mm a sieved soil sample <4 mm is used in the SAT test.
2. Penn State Soil Abrasion Testing System: The Penn State University research group was the first to develop and describe a dedicated abrasion test for in-situ soil. It provides an opportunity to evaluate the influence of water content variations and rotation speeds on a soil sample and is capable to test soils consisting up to cobble dimensions, at 0 to 10 bars pressure.
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9. 3. Newly-Developed Abrasion Test (NDAT): The test is carried out under pressure, it measure abrasive wear of particles and tribo-corrosive wear on the introduction of liquid and additives.
4. Politecnico di Torino Test: It is a comparative wear tests on conditioned soil. The test comprises of a tank containing a soil or rock sample and a circular metal disc exposed to wear, and compressed with 2 kPa confinement pressure both prior to and during testing.
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10. 10 of 22 New NTNU Test The PSAI Test The NDAT Test
ITIOLA I.O. ( Master’s Thesis Presentation T&TBM 2014)
The Politecnico di Torino Test
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11. OBJECTIVES OF THE STUDY
The objectives of this research is to verify the operation and effectiveness of different approaches which could be designed to reduce the wear impact on disc cutters by investigating and comparing the significance of using:
Dry material;
Material conditioned with water only (w = 10%);
Material conditioned with 7.5% of water and 2.5% of additives (w = 10%).
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12. MATERIALS AND METHODS Rock Sample Description
The test was performed on soil obtained from Sibelco quarry area of Piedmonte region in Italy consisting of 20 kg of quartz sand, weight of water was 0.2% of sample, disc diameter = 12inches, time duration per test was 10minutes at 320rpm and frequency of 5Hz.
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13. Shows the Testing Device During Operation in the Politecnico Di Torino Tunnelling and Underground Space Centre Laboratory (TUSC).
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14. RESULTS AND DISCUSSION
Effectiveness and Comparison on the Outcomes of Results Obtained from Dry Sample and other Conditioned approach on Rock Wear Reduction
The data obtained from the dry sample are not significant enough due to the segregation of larger particles from the fine particle (Material not in close contact with the disc). Substantially, the quartz grains of larger dimensions are removed from the inertia rotation of the disc which led to obtaining values ​​of weight loss and average torque that are relatively low.
Due to the relatively low value obtained from the dry sample, further investigation was decided on the same sample material to conduct another two tests which was to condition the material with w = 10% using only water and secondly to use 10% by weight consisting of 7.5% water and 2.5% of additive. A significant reduction in the weight loss (wear) of about 33% (197g of weight loss) and in torque Nm (10%) was deduced which means that use of foam had much impact on wear reduction than the use of water alone as a means of conditioning for wear reduction.
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15. Shows the traces of the aluminium weight loss due to the rotation of the disc and a clear separation of the larger grains of quartz from the fine particle.
Microscopic image of the quartz grain
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16. Shows the Outcomes for the Weight Loss at Different Stage of the Test; for Dry sample, 10% of Water Content Sample and 10% of Foam Sample.
Shows the Outcomes for the Average Torque at Different Stage of the Test; for Dry Sample, 10% of Water Content Sample and 10% of Foam Sample.
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17. Effect of Foam Additives on Rock Wear Reduction
After seeing the outcomes of the results discussed above which describes the insignificant result obtained from the dry sample, a step further to better understand the relationship between the weight loss of the disc and the average torque was by using foam with FER of 12 and FIR of 40 for the analysis of the wear reduction. The Table below shows the outcomes of the results as a means of comparison between dry sample and the use of the foam additive.
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18. Shows the Results Obtained from the Test for Weight Loss and Average Torque on Dry and Conditioned Sample
DRY SAMPLE
CONDITIONED SAMPLE
Weight loss [g]
0.015
0.420
Average torque
0.176
0.163
CONDITIONED
CONDITIONED
Shows the weight loss of the dry and conditioned sample wear impact on the Disc cutter.
Shows the average torque of the dry and conditioned sample wear impact on the Disc cutter.
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19. CONCLUSION AND RECOMMENDATION
Based on the results obtained from laboratory tests in determining the wear impact of Quartz sand abrasiveness on Tunneling Boring Machines (TBM) disc cutter, it can be inferred that:
The dry sample result are not significant enough due to the segregation of the large particles from the fine particle, because the quartz grains of larger dimensions were removed from the inertia rotation of the disc which led to obtaining values ​​of weight loss and average torque that are relatively low.
Comparison between tests carried out on material conditioned with water only (w = 10%) and Conditioned material consisting of 7.5% of water and 2.5% of additives (w = 10%) gave a significant reduction in the weight loss (wear) of about 33% (197g of weight loss) which means that the use of foam had much impact on wear reduction than the use of water alone as a means of conditioning for wear reduction while for the torque, a difference of Nm (10%) was calculated.
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20. STABILFOAM 3000TS produced by MAPEI show significant results for wear reduction in both weight loss and average torque in the test.
Although, this test has shown that conditioning of soil or rock during excavation with chemical agents has more impact on wear reduction than using water or without water but a certain factor that needs to be considered is the cost of this product and its effect on the total cost of a project.
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