Experimental Study of Bridge Foundation Reinforced with Front and Back Rows of Anti-Slide Piles on Gravel Soil Slope under El Centro Waves

Round 1

Reviewer 1 Report

In this article, the authors did study under the application of front and back rows anti-slide piles. The shaking table model test was conducted in order to characterize the impact of dynamic loading on such structure. Below are my comments and suggestions.

 

1. Featured application the sentence “The seismic reinforcement design of bridge foundation reinforced with front and back rows of anti-slide piles on gravel soil slope.” needs attention.
2. In Abstract: the PGA needs to be clarified.
3. Literature review:
   1. “Liu et al. [1] took a road cutting slope site of Yumeng railway as an example, analyzed the change law of the slope acceleration and soil pressure behind the pile through shaking table test, and evaluated the seismic reinforcement effect.”

And, what have they found? Please, provide some insides of this test results in the manuscript.

1. “At the same time, some scholars carried out theoretical and experimental studies on the characteristics of force and deformation of slope bridge foundation.

Which ones? Please, support this sentence with the literature.

1. “The Chengdu–Lanzhou Railway crosses the eastern side of the Qinghai–Tibet Plateau. The seismic fault zone along the railway has a complex structure [8], and earthquakes are prone to occur frequently in this region, as shown in Figure 1. In this study, taking the slope worksite of the Jiuzhaigou Bridge on the Chengdu–Lanzhou Railway as a real-world engineering prototype, a shaking table model test was conducted on the bridge foundation reinforced with the front and back rows of anti-slide piles on the gravel soil slope. The model was subjected to El Centro waves with
   different peak accelerations to obtain the distribution characteristics of the thrust of the colluvial gravel soil landslide. The stress-induced deformation patterns of the pier pile foundation as well as the front and back rows of anti-slide piles, in addition to the stress-induced deformation compatibility of the three, were analyzed. The variation pattern of the PGA amplification factor of the gravel soil slope under seismic waves was investigated, the evolution of the anti-slide pile damage and slope failure was summarized, and a new method for analyzing the acceleration response of the slope model by using a two-dimensional equipotential map was developed. The results revealed the dynamic response characteristics of the front and back rows of anti-slide piles, pier pile foundation, and gravel soil slope, and provided the necessary technical references for the seismic reinforcement design of a bridge foundation on a gravel soil slope.”

This whole paragraph is too long for the literature review. The authors can move part of it to ne Materials and Methods, or the authors can extend this paragraph with the literature (to which I strongly encourage, otherwise, the literature review will be too laconic).  For example, why the El Centro waves? Maybe someone did similar tests with the use of this kind of wave to analyze the anti-slide piles. Did someone studied such variation patterns in such conditions, what ones found, and what the authors suppose to find in this study etc.?

1. Overview of Workside – line 2 of paragraph : delete space in geo-coordinations.
2. Similarity design – line 4 The sentence with the C explanation is unclear and needs attention. Please denote all constants, parameters etc. In italic
3. The sililarity constant was “set” to 1.0?
4. What are the physical properties of the mixture of bentonite and fine sand used to simulate the potential sliding surface? Since the unit weight similarity constant was set to 1.0 as well as the damping and shear modulus ratio similarity constant, the additional information is required that the authors produced appropriate test geotechnical conditions.
5. Figure 11. The photos, are taken from different perspecives and are bit hard to understand. The a and b are taken from the top and c and d are taken from the downside? Please reconsider to give more explanation in Figure Title.
6. In the conclusion part, to sum up, the tests in this article, the recommendation paragraph should be introduced. Right now, the only recommendation is to use a pile foundation behind the pier to be used as an analysis subject in seismic design. Some recommendations based on vertical distribution of peak earth pressure or pile shaft bending moment would significantly increase the value of this article.

 

 

Author Response

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Author Response File: Author Response.doc

Reviewer 2 Report

There are 3 major issues that must be addressed in a review of this paper.

1. The importance of studying of some rescue technologies in the case of slope stability problem induced by seismic excitation.
2. The adequacy of laboratory model and its suitability for formulating conclusion. Especially when we deal with soil dynamics and real technical problem.
3. General structure of the work, its ”readability” etc.

In my opinion, the Authors properly addressed their attention to already existing constructions that might need some additional supporting construction. I’d like to mention, however, that most of the problems of analyzed cases should be revealed in course of design or even pre-design period of infrastructural works (roads, bridges). Maybe I did not read this paper cautiously enough, but I’d suggest a little wider description of authors motivation related to the analyzed case study of Juizhaigou Bridge. Figure 2 should be checked again. Fonts seem to be too large. “United supporting of … “ should be somehow explained as the whole foundation system seem to be very complex. Was it intentional or just the complicity is the result of the problems that appeared at construction period?

Concerning the adequacy of laboratory model, I appreciate authors efforts to consider the effect of scale (1:70) in the design of the experiment. For the same reason I’d suggest to soften a little the conclusions as they can only be based on qualitative (and not reliable quantitative) analysis. I understand that laboratory testing follows the in-situ design scheme. But from my experience, the piles that are devoted to cut the potential slip line does not need to be constructed till the ground level. The results shown on figures 14 and 15 show that both: earth pressures and bending moments appear to be largest around the slip line. Please try to explain because I may be wrong with my understanding of the actual situation.

The technical structure of the work is absolutely acceptable for me. The conduct of the analysis is rather clear (except for some doubts that I raised in previous paragraph).

In may opinion, the paper may be published only after some smoothing of the introductory part.

Author Response

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Author Response File: Author Response.doc

Reviewer 3 Report

The manuscript investigates the seismic reinforcement design of bridge foundation reinforced with front and back rows of anti-slide piles on gravel soil slope using a shaking table test. It also introduces a new method for analysing the acceleration response of the slope model by using a two-dimensional equipotential map.

The study is very interesting and practical. The manuscript is well-organised and generously delivered the details of the study, modelling, and results. There are a few comments from this reviewer to be considered by the authors.

The abstract includes more details of the results than what it should. It is recommended that the authors make the abstract more concise in terms of revealing the detailed results of the study.

What method was used by the authors to construct the sliding surface by the mixture of bentonite and fine sand? How did they constructed the mix to the specific density and moisture content in the model? What method did they use to avoid evaporation of the water during the construction of the model and after that?

Installing accelerometers in the soil is challenging to the fact that they may (or will) move/rotate by the soil and may not represent the real acceleration because of the difference between their axis of measurement and the direction of shaking. What did the authors do to avoid this problem? The same applied to the reading of the Earth pressure cells installed in the soil layer.

In addition, from the instrumentation diagram in Figure 6, it appears that there is no accelerometer installed on the rigid wall of the box. The authors stated that they used anti-vibration materials on the inside of the box to reduce the reflection effect of the seismic wave. However, the effectiveness of this can be proven by comparing the acceleration graphs for a point on the outside of the box with a point inside the box with the applied anti vibrating materials. A clarification on this matter would be appreciated.

Author Response

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Author Response File: Author Response.pdf