Stress Evolution in Linear Cutting Tests: Laboratory and Numerical Methods

Round 1

Reviewer 1 Report

There are some comments requiring to reconsider:-

Abstract:

p. 11: a CCS cutter_ Could the authors specify what CCS stands for.

1. Introduction:

P. 421-42: the sentence should reformulate.

p.51-52: the sentence should rewrite

 

2. Materials and Methods

p. 73-76: ordinal numbers:  following the right sequence and should reconsider.

p. 80: Definite article "the" not necessary

 

3. Results

P. 86: Units for SE, E and M should mention

P. 99: weighting or weighing should be used?

P.100-102: Could the autors estimate fracture area and add it to diagram 3.

Figure 2. missing scale bar on the all images.

According to Figure 2, could the authors take either the spacing 40 mm or 30 mm for both the yellow and red sandstone?

Figure 3. should the authors refine figure 3 and  change to scatter with straight lines? could the authors explaine why the curves for yellow sandston drop off at the pentration depth of 3.5 mm and 4.5 mm and compare this with red sandstone.

p. 105: missing units?

P. 119-129: Could the authors  check the rock microstructure what happend in it in respect to dislocation density? if possible, check that when the test will interrupt before the cutting distance 70 mm?

p. 130: the text is not really accurate for yellow sandstene.

Figure 4. Could the authors explaine what happened at the cutting distance of 35 mm?

Figure 4 and 5 should enlarge the font style?

Figure 5b: Should the authors change to scatter with straight lines and explaine the behaviour of both tested specimens?

P. 153: Could the authors relate symbols with text words the tensile and shear and compressive stress and put it in the round bracket?

Figure 7: Missing scale bars for all images?

Figure 8: Could the authors put the penetration depth on the all three subfigures?

 

P. 232-243: Could the test interrupt to investigate the microstructure in terms of dislocation density?

P.252 and Figure 15 should be enlarged? and the lines should change to scatter with straight lines? Explaine?

Author Response

Dear Expert: Thanks for your hard work on our manuscript. According to your beneficial comments, we have revised the manuscript. Best wishes to you. Sincerely Yours, Authors of this manuscript Comment #1: 11: a CCS cutter_ Could the authors specify what CCS stands for. Response: CCS stands for the constant cross section. According to your kind recommendation, the meaning of CCS is added in Abstract in blue words. Comment #2: 421-42: the sentence should reformulate. Response: According to your beneficial comments, this sentence has been reformulated. Comment #3: 51-52: the sentence should rewrite Response: According to your comments, the sentence has been rewritten. Comment #4: 73-76: ordinal numbers: following the right sequence and should reconsider. Response: According to your beneficial comments, ordinal numbers have been added. Comment #5: 80: Definite article "the" not necessary Response: Thanks for your recommendation, ‘the’ has been deleted. Comment #6: 86: Units for SE, E and M should mention Response: Thanks for your recommendation, the units have been added in blue words. Comment #7: 99: weighting or weighing should be used? Response: Thanks for your comments, ‘weighting’ is substituted by weighing. Comment #8: 100-102: Could the autors estimate fracture area and add it to diagram 3. Response: Thanks for your recommendation, the estimated fracture area has been added in diagram 3. Comment #9: Figure 2. missing scale bar on the all images. Response: According to your suggestion, the scale bar has been added. Comment #10: According to Figure 2, could the authors take either the spacing 40 mm or 30 mm for both the yellow and red sandstone? Response: Thanks for your comments. Similar phenomena were observed for the other tests. Figure 2 shows the typical fractures. Comment #11: Figure 3. should the authors refine figure 3 and change to scatter with straight lines? could the authors explain why the curves for yellow sandstone drop off at the penetration depth of 3.5 mm and 4.5 mm and compare this with red sandstone. Response: According to your beneficial comments, Figure 3 has been refined. We are really moved by your rigorous scholarship. Indeed, the increase in penetration promote rock fractures between cuts. The chips were collected and weighed after two cuts. Nevertheless, rock specimens may contain minor defects and may further influence chip formation between cuts. The decreases in chip mass for the yellow sandstone when the penetration depths are 3.5 mm and 4.5 mm may be attributed the the minor defects for rock specimens. Nevertheless, Figure 3 shows that the increase in penetration integrally increases the chip mass. Comment #12: 105: missing units? Response: Thanks for your comments, the missing units have been added. Comment #13: 119-129: Could the authors check the rock microstructure what happend in it in respect to dislocation density? if possible, check that when the test will interrupt before the cutting distance 70 mm? Response: We are inspired by your recommendations. However, our institute lacks essential equipment to support this work. If we can get sufficient financial support in the future, we will conduct this inspiring work. Comment #14:. 130: the text is not really accurate for yellow sandstene. Response: We are sorry for our ignorance. The text has been checked. Comment #15: Figure 4. Could the authors explaine what happened at the cutting distance of 35 mm? Response: A large drop in rolling force occurs when the cutting distance is 35 mm. This large drop may result from obvious fracture propagation. Nevertheless, we lack essential equipment (such as the high speed camera) to analyze the relation between potential crack propagation and the rolling force fluctuation. Thus, in the following numerical simulation, this phenomenon is studied. Comment #16: Figure 4 and 5 should enlarge the font style? Response: Thanks for your recommendation, the font style has been enlarged. Comment #17: Figure 5b: Should the authors change to scatter with straight lines and explaine the behaviour of both tested specimens? Response: According to your suggestion. Figure 5b has been revised. Corresponding descriptions have been added in blue words. Comment #18: 153: Could the authors relate symbols with text words the tensile and shear and compressive stress and put it in the round bracket? Response: Thanks for your kind recommendations. Tensile, shear and compressive stresses are related to σt, τ and σc, respectively. Comment #19: Figure 7: Missing scale bars for all images? Response: Thanks for your comments, the scale bars have been added. Comment #20: Figure 8: Could the authors put the penetration depth on the all three subfigures? Response: According to your suggestions, the penetrations have been added in Figure 8. Comment #21: 232-243: Could the test interrupt to investigate the microstructure in terms of dislocation density? Response: Thanks for your recommendation. We are really sorry that we are unable to conduct this investigation because of our limited knowledge about dislocation density. Comment #22: 252 and Figure 15 should be enlarged? and the lines should change to scatter with straight lines? Explaine? Response: Thanks for your recommendation. Figure 15 has been revised. Thanks again for your hard work and beneficial comments on our manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, small scaled linear cutting tests are carried out and numerical simulations are performed using PFC 3D. The relation between the fluctuations of rolling force and the rock fractures is revealed. Overall, some useful conclusions have been obtained. It is recommended to be accepted for publication pending suitable minor revision.

 

1. In this paper, the spacing of cutter was set to 30mm and 40mm, please explain the basis for the design. Although the concrete provides a constraint to the rock sample, the confining pressure can be considered in the further design of the test.

2. In Figure 3, the results are widely dispersed. Please prove the reliability of the rule.

3. There are few errors in the Figure 6 (a) and Figure 8 (a) , and the author should checked and replaced it.

4. The conclusion shows that the increase in penetration can promote cutting efficiency. But the penetration range of the test is small, so it is impossible to prove the influence of larger penetration on the rock-breaking efficiency. Please define the scope of application of the conclusion

Author Response

Dear Expert: Thanks for your hard work on our manuscript. Your beneficial comments and recommendations are critical to the improvement of our manuscript. Now, we are trying to submit the revised version. Best wishes to you. Sincerely Yours, Authors of this manuscript Comment #1: In this paper, small scaled linear cutting tests are carried out and numerical simulations are performed using PFC 3D. The relation between the fluctuations of rolling force and the rock fractures is revealed. Overall, some useful conclusions have been obtained. It is recommended to be accepted for publication pending suitable minor revision. In this paper, the spacing of cutter was set to 30mm and 40mm, please explain the basis for the design. Although the concrete provides a constraint to the rock sample, the confining pressure can be considered in the further design of the test. Response: Thanks for your kind recommendation. The small-scaled linear cutting apparatus was prefabricated based on the previous apparatus [1, 2]. The specimen length was 100 mm. Thus, the spacing in the present study is limited. To provide a margin between the cut and the boundary, the spacing was set to 30 mm and 40 mm. The design basis has been added in red words. In addition, we are greatly inspired by your recommendation. We will try to apply confining pressure on the specimen by improving this apparatus. Comment #2: In Figure 3, the results are widely dispersed. Please prove the reliability of the rule. Response: Thanks for your comments. Rock specimens may contain minor defects. These defects may result in disperse of the rock chips. Nevertheless, the collected chip mass (Figure 3) shows that the increase in penetration integrally increases the chip mass. Comment #3: There are few errors in the Figure 6 (a) and Figure 8 (a) , and the author should checked and replaced it. Response: Thanks for your comments. Figure 6(a) and Figure 8(a) have been checked. Comment #4: The conclusion shows that the increase in penetration can promote cutting efficiency. But the penetration range of the test is small, so it is impossible to prove the influence of larger penetration on the rock-breaking efficiency. Please define the scope of application of the conclusion Response: Thanks for your comments. Indeed, the penetration is relatively small. Thus, according to your suggestion, the penetration range has been added in conclusion in red words. Thanks again for your hard work and beneficial comments on our manuscript. References [1] Entacher M.; Schuller E.;Galler R. Rock Failure and Crack Propagation Beneath Disc Cutters. Rock Mech. Rock Eng. 2015, 48, 1559-1572. [2] Entacher M.; Lorenz S.; Galler R. Tunnel boring machine performance prediction with scaled rock cutting tests. International Journal of Rock Mechanics & Mining Sciences 2014, 70, 450-459.

Author Response File: Author Response.pdf