Determining the Shear Resistance in Landslides with Respect to Shear Displacement and Shearing Time in Drainage-Controlled Ring Shear Tests

Round 1

Reviewer 1 Report

The manuscript “Determining the shear resistance in landslides with respect to shear displacement and shearing time in drainage-controlled ring shear tests” presents the study of the residual shear stress of weathered landslide materials.

The goals and motivation of such a study are relatively straightforward. The manuscript is well-structured and presented. The presented investigation can be used to estimate the reactivation of slope movement.

The paper can be recommended to Applied Sciences.

Additional comments that need to be addressed:

• The sentence: ‘It should also be noted that understanding the transitional mechanism from sliding to flow is very important to mitigate landslide hazards, but it is still very difficult to examine the development of shear stress against strain at the onset of mass movements.’ should be ‘It should also be noted that understanding the transitional mechanism from sliding to flow is very important to mitigate landslide hazards. However, it is still complicated to examine the development of shear stress against strain at the onset of mass movements.’
• The sentence: ‘The ring shear characteristics of landslide materials containing a large amount of sand-size particles are examined with respect to different shear displacements and shearing times.’ should be ‘The ring shear characteristics of landslide materials containing many sand-size particles are examined concerning different shear displacements and shearing times.’
• The sentence: ‘The coupling of the generation of pore water pressure and the corresponding response of shear stress is not a goal of this study, but the shear resistance obtained from direct shear tests and ring shear tests are compared to estimate the shear strength of landslides.’ should be ‘The coupling of the generation of pore water pressure and the corresponding shear stress response is not a goal of this study, but the shear resistance obtained from direct shear tests and ring shear tests are compared to estimate the shear strength of landslides.’
• The sentence: ‘First, the measurements of shear stress against shear displacement and shear speed are examined. ’ should be ‘First, shear stress measurements against shear displacement and shear speed are examined.’
• The sentence: ‘The soil sample is saturated slowly by injecting water in the ring shear box.’ should be ‘The soil sample is saturated slowly by injecting water into the ring shear box.’
• The sentence: ‘It takes approximately 1 hour for weathered soils, which are composed of coarse-grained sediments.’ should be ‘It takes approximately 1 hour for weathered soils composed of coarse-grained sediments.’
• The sentence: ‘When the degree of saturation is greater than 90%, the soil sample is normally compressed without any change in internal soil conditions: it is compressed up to 50 kPa per 300 seconds, and then the normal stress remains constant during all tests.’ should be ‘When saturation is greater than 90%, the soil sample is generally compressed without any change in internal soil conditions: it is compressed up to 50 kPa per 300 seconds.’
• The sentence: ‘Figure 4 presents the results of shear stress-displacement curves obtained from the drained and undrained conditions at different shear displacements, i.e., shearing lengths equal to 10, 30, 50, 100, 110 mm in ring shear tests, corresponding to strains of 2%, 5%, 9%, 18%, and 20%.’ should be ‘Figure 4 presents the results of shear stress-displacement curves obtained from the drained and undrained conditions at different shear displacements, i.e., shearing lengths equal to 10, 30, 50, 100, 110 mm in ring shear tests, corresponding to strains of 2, 5, 9, 18, and 20%.’
• The sentence: ‘In the postfailure stage, spreading and high mobilization of debris flow transformed from the initial slope failure may be influenced by mixing with broken landslide sediments of preexisting deposition in the flow channel.’ should be ‘In the post-failure stage, spreading and high mobilization of debris flow transformed from the initial slope failure may be influenced by mixing with broken landslide sediments of preexisting deposition in the flow channel.’
• The sentence: ‘It is also interesting that the shear stress seems to decrease from high shear stress to low shear stress and stabilize when the speed has the lowest value.’ should be ‘It is also interesting that the shear stress seems to decrease from high to low shear stress and stabilize when the speed has the lowest value.’
• The sentence: ‘For a given test condition, i.e., controlled drainage and shear speed, the soil behavior has almost the same strain-softening characteristics: that is, there are distinct peak and residual values.’ should be ‘For a given test condition, i.e., controlled drainage and shear speed, the soil behavior has almost the same strain-softening characteristics: there are distinct peak and residual values.’
• The sentence: ‘At a shear speed of 0.1 mm/s (such as a moderate landslide rate), however, the peak shear stress has a large range, while the residual shear stress has a relatively small range.’ should be ‘At a shear speed of 0.1 mm/s (such as a moderate landslide rate), however, the peak shear stress has an extensive range, while the residual shear stress has a relatively small range.’
• The sentence: ‘To determine the shear resistance along the slip surface, direct shear tests and ring shear tests are applicable.’ should be ‘Direct shear tests and ring shear tests are applicable to determine the shear resistance along the slip surface.’
• The sentence: ‘Based on the test results, the factor of safety can be determined with respect to the different slopes and soil thicknesses.’ should be ‘The safety factor can be determined for the different slopes and soil thicknesses based on the test results.’
• The sentence: ‘In conclusion, the use of residual shear stress obtained from this study can be applied at the beginning of landslide occurrence when we can take into account the reactivation of the slope.’ should be ‘In conclusion, the use of residual shear stress obtained from this study can be applied at the beginning of landslide occurrence when we can take into account the reactivation of the slope.’

Author Response

Considered. Thank you for your recommendation.

Reviewer 2 Report

Comments for author File: Comments.docx

Author Response

Considered. The attached file is author's response to your comments.

Thank you for your time and consideration.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors Manuscript ID: applsci-1711073-R2
Title: “Determining the shear resistance in landslides with respect to shear displacement and shearing time in drainage-controlled ring shear tests” Sueng-Won Jeong

This manuscript is to be Accepted the manuscript in the present form. 

Thank you