Pressure Characteristics of Landslide-Generated Waves on Bridge Piers
Round 1
Reviewer 1 Report
Dear author(s):
The present manuscript shows a promising paper, suitable for publication in your esteemed journal, with some novel aspects and a well-structured preparation process. However, in its current state, a definitive decision regarding approval or rejection cannot be made until the necessary amendments are undertaken to enhance the clarity of the experimental aspects and results in the manuscript. All the required amendments are as follow:
- The abstract requires a thorough revision of each paragraph, removing any additional sentences, and placing greater emphasis on effectively presenting the practical results obtained from the practical side
Introduction:
- Give a suitable reason for the following sentence: “The impact of landslide-generated impulse waves is considered one of the notable secondary hazards and is sometimes stronger than the landslide itself, especially in the reservoir area” in introduction.
- The following sentence needs to support by some real examples: “Numerous reservoir areas that have suffered from landslides are in mountainous regions, where landslide-generated wave formation and propagation are greatly influenced by the river channel and opposite bank”.
- The previous studies mentioned in the introduction part (i.e., from 14-28) must be converted to a table contains the important results of them in addition to the parameters used in their studies. Moreover, the table preferer to contain a column of the parameters that don’t be used by each author. The studies must be arranged according to chronology.
- The last paragraph of introduction, which represents the aim of the paper, must be reformulated carefully and need to clarify the goal in better manner.
Experimental Setup:
Please clarify the following points in details to better clear this section of manuscript:
- How to a carriage, chute, and landslide mass can simulate landslides? Give a sufficient explanation
- Why you using iron to construct the carriage and chute? Give the unique characteristics which realize the iron among other metals
- Explain how can chute's bottom plate simulate the sliding surface?
- Explain the following sentence clearly with dimensions (roughly): “the size of individual blocks was determined based on the degree of fissure development and the width of the fissures”
- What is the reason for using this range of density? i.e., 2.3-2.8 g/cm³?
- Could you please provide a detailed table listing the properties of the clay that were manipulated to achieve a density of 2.5 g/cm³ in this section.
- Figure 1 lacks clarity and should be replaced with a more suitable image, ideally positioned adjacent to its schematic diagram for a cohesive presentation.
- All units of measurement must be standardized, using either (m) or (cm), consistently across figures, text, or any other relevant context.
- This section should be accompanied by a clear image illustrating the '3D wave basin,' ideally placed adjacent to Figure 2 to facilitate showing them together.
- “The slopes on both sides are 20° and 33° respectively”, What is the justification for utilizing these angles? Provide a valid explanation
- This paragraph require sentences restructuring and an elucidation of the rationale behind utilizing these dimensions: “A bridge pier ……. The depth of the river channel was â„Ž, as illustrated in Figure 2”.
- Finally, this section must be included the % accuracy of the results obtained due to this set up with the real landslide.
Forms and Distribution of Wave Pressure
- The author(s) present numerous results in this section, but the explanations are very simple and do not align with these findings. Therefore, it is essential to improve the explanations of this section, providing distinct explanations for each result.
- All the diagrams in Figure 4 should be substituted with other clearer ones.
- The discussion section should be precisely integrated with the results portion, adequately elucidating each paragraph on its own.
- Conclusions: This part needs to reformulate its sentences carefully, and clarify the findings of the manuscript obtained in a more comprehensible and convenient manner.
- References (optional): If outdated references, older than a decade, are not essential, it is advisable to substitute them with more recent ones, (if feasible).
Moderate editing of English language required
Author Response
Response to Reviewer 1 Comments
Dear reviewer,
We appreciate the time and effort that you dedicated to providing the feedback on our manuscript and are grateful for the insightful comments on our paper. We have studied insightful comments and tried our best to revise the manuscript. We used red fonts to mark revisions, detailed review comments reply as follows:
The present manuscript shows a promising paper, suitable for publication in your esteemed journal, with some novel aspects and a well-structured preparation process. However, in its current state, a definitive decision regarding approval or rejection cannot be made until the necessary amendments are undertaken to enhance the clarity of the experimental aspects and results in the manuscript. All the required amendments are as follow:
- The abstract requires a thorough revision of each paragraph, removing any additional sentences, and placing greater emphasis on effectively presenting the practical results obtained from the practical side
Thank you for your suggestions. Abstract has been thoroughly revised and improved as per the requirements.
In the reservoir area, landslides can generate waves that pose a significant threat to bridge piers, endangering both property and human safety. This study utilized 3D water tank experiments to simulate the generation of landslide-induced waves and their impact on bridge piers located on both riverbanks. The analysis focused on the types and distribution patterns of wave pressures on bridge piers.The results reveal the following key findings:（1）The results show that the wave pressures on the piers can be classified into two types: Pulsating pressure（）and Resonance pressure（）. represents high-frequency vibrational waves generated when bridge piers resonate during wave action. is observed primarily in deep water conditions and on the opposite riverbank, with frequencies ranging from 300 to 900 Hz. represents the pressure generated during the wave action process. closely correspond to the wave height-time process, with frequencies ranging from 0.2 to 0.5 Hz. occurs prior to .（2）On the bridge piers of the opposite riverbank, exhibits a nearly vertical distribution along the water depth, while on the same side, exhibits a sawtooth-like decrease along the water depth. increases with greater landslide volume and steeper landslide angles, and the maximum wave pressure distribution occurring near the water surface.（3）The distribution of along the water depth exhibits three forms: multi-peak, single-peak, and none-peak, with the maximum positions for all conditions of occurring at approximately one-third of the water depth from the surface (). Finally, predictive formulas for the maximum wave pressures are provided.
Introduction:
- Give a suitable reason for the following sentence: “The impact of landslide-generated impulse waves is considered one of the notable secondary hazards and is sometimes stronger than the landslide itself, especially in the reservoir area” in introduction.
Thank you for your suggestions, and we have used an example to illustrate this sentence.
The largest landslide generated wave event occurred in 1963 in Italy as 260 million cubic Meters of rock fell into the reservoir of the Vajont Dam, built in 1959, producing an enormous flooding due to at least 50 million cubic Meters of water. The dam did not suffer any serious damage, but flooding due to the overtopping height of about 245 m above the dam crest destroyed several villages in the valley and killed almost 2000 people [1].
- The following sentence needs to support by some real examples: “Numerous reservoir areas that have suffered from landslides are in mountainous regions, where landslide-generated wave formation and propagation are greatly influenced by the river channel and opposite bank”.
Thank you for your suggestions, and we have incorporated relevant examples into the manuscript.
In June 2007, a massive landslide with a volume of three million cubic meters oc-curred at the Da Yan Tang location, resulting in waves surging as high as 4 m. This event had varying impacts on three nearby townships, leading to adverse consequenc-es such as casualties and damage in the upstream hazard zone and one downstream township. On November 23, 2008, a widespread landslide took place at the Gong Jia Fang slope in Wushan County. This event subsequently generated enormous waves. Post-event investigations revealed that the main components of the landslide consisted of limestone and marl. The total volume of the collapse reached 380,000 cubic meters, with an approximate entry width of 194 m and entry depth of around 15 m. After sliding into the water, it was completely submerged, resulting in waves reaching a maximum height of 31.8 m, severely affecting navigation in the area. In June 2015, a landslide occurred at the mouth of the Da Ning River on the north bank in Wushan, Chongqing. Approximately 230,000 cubic meters of rock and soil rapidly slid into the river, generating massive waves nearly 6 meters high. This event led to the sinking of one coast guard vessel and the capsizing of 9 small fishing boats and 7 private vessels that were moored on the opposite shore. Furthermore, the wave propagation along the opposite bank resulted in injuries and fatalities, with a total of 6 casualties.
- The previous studies mentioned in the introduction part (i.e., from 14-28) must be converted to a table contains the important results of them in addition to the parameters used in their studies. Moreover, the table preferer to contain a column of the parameters that don’t be used by each author. The studies must be arranged according to chronology.
Thank you very much for your suggestions. Using tables can make literature research more visually understandable and easier to compare. Based on your advice, we have made detailed revisions. The Introduction part covers the introduction of landslide model experiments and the effects of landslide-generated waves on structures. As per your request, we have replaced the references in the introduction related to landslide model experiments with more milestone papers and created a table for better presentation. In the section discussing the effects of landslide-generated waves on structures, the literature varies in terms of research focus and lacks a unified set of parameters, making it less reader-friendly when presented in a table.
Noda [2] stands among the pioneering researchers who conducted experimental investigations into landslide-generated waves generated by solid blocks. Noda categorized these waves into four distinct patterns: nonlinear oscillatory, nonlinear transition, solitary-like, and dissipative transient bore. Laboratory investigations carried out by Kamphuis and Bowering [3] regarding landslide-generated waves revealed that the characteristics of these waves primarily depend on the slide's volume and the Froude number at the moment of impact with the water. Additionally, wave propagation speed can be approximated using solitary wave theory. Huber and Hager [4] conducted a series of three-dimensional experiments involving granular landslides falling into a water tank. Their findings suggested a correlation between wave height and non-dimensional landslide volume values. Walder et al. [5] studied the near-field characteristics of landslide-generated waves caused by solid blocks in a two-dimensional physical model. Their research highlighted that key factors governing near-field wave properties include non-dimensional landslide volume per unit width, non-dimensional submerged time of motion, and non-dimensional vertical impact speed. Fritz et al. [6] conducted comprehensive two-dimensional laboratory experiments with granular materials. They presented empirical equations for predicting the patterns of LGWs based on slide properties and also introduced empirical equations for predicting energy conservation from the slide to the water. Panizzo et al. [7] performed three-dimensional experiments and concluded that the maximum generated wave height was primarily influenced by the non-dimensional time of underwater landslide motion and the surface of the landslide front. As an illustrative example of experimental setups, Ataie-Ashtiani and Nik-Khah [8] conducted 120 laboratory tests using both rigid and deformable slide masses. They found that the maximum wave crest amplitude was strongly affected by bed slope angle, landslide impact velocity, thickness, kinematics, deformation, and weakly by landslide shape. Mohammed and Fritz [9] conducted physical modeling of landslide-generated waves using deformable granular landslides in a three-dimensional wave basin. Their study highlighted that the dominant control over wave characteristics lies in the landslide Froude number. They reported that 1–15% of the kinetic energy of the landslide at impact was converted into wave energy. Heller and Spinneken [10] conducted tests to investigate the influences of the slide Froude number, relative slide thickness, and relative slide mass on the characteristics of landslide-generated waves. In a subsequent study, Heller and Spinneken [11] explored the effects of the water body geometry on wave characteristics in both near- and far-fields, using both two- and three-dimensional physical models. They observed that, for a small slide Froude number, relative slide thickness, and relative slide mass, three-dimensional wave heights were considerably smaller both in the near- and far-field compared to those in two dimensions. Lindstrøm [12] conducted experimental investigations into landslide-generated waves in a two-dimensional wave tank. He employed five different slide materials, including block slides and four granular slides with grain diameters ranging from 3 to 25 mm.
Table 1 Different reference experimental conditions
|
Reference |
Model dimensional |
Water tank Length (m) |
Water tank Weith (m) |
Water tank Height (m) |
Bed slope (°) |
Slide mass specifications |
|
Noda (1970) |
2D |
- |
- |
- |
- |
Solid rectangular box |
|
Kamphuis and Bowering (1970) |
2D |
45.00 |
1.00 |
023-0.46 |
45 |
Steel box |
|
Huber and Hager (1997) |
3D |
30.00 |
0.50 |
0.50 |
28- 60 |
Granular matenal |
|
Walder et al. (2003) |
2D |
3.00 |
0.28 |
1.00 |
10- 20 |
Hollow rectangular |
|
Friz et al (2004) |
2D |
11.00 |
0.50 |
1.00 |
45 |
Granular material |
|
Panizzo et al. (2005b) |
3D |
11.50 |
6.00 |
080 |
16- 36 |
Solid rectangular box |
|
Ataic-Ashiani and Nik-Khah(2008) |
2D |
3.60 |
2.50 |
0.80-0.50 |
15- 60 |
Solid and granular |
|
Mohammed and Fritz (20I2) |
3D |
48.80 |
2.65 |
0.30-1.20 |
27 |
Granular |
|
Heller and Spinneken (2013) |
2D |
24.50 |
0.60 |
0.30-0.60 |
45 |
Solid |
|
Heller and Spinneken (2015) |
2D, 3D |
21,20 |
0.60, 7.40 |
0.24, 0.48 |
45 |
Solid |
|
Lindstrom (2016) |
2D |
7.30 |
0.20 |
0.10 |
35 |
Solid and granular |
- The last paragraph of introduction, which represents the aim of the paper, must be reformulated carefully and need to clarify the goal in better manner.
Thank you very much for your suggestions, we have made detailed revisions.
Bridges are the most common transportation infrastructure in reservoir areas. Landslides in these regions can directly destroy piers and roads along their paths. Furthermore, during the secondary wave propagation process, they can also damage or wash away piers. Therefore, targeted protection and monitoring of piers are essential. To achieve this, it is crucial to understand the mechanisms of wave action on piers, including the types and forms of pressure on piers under wave action. This understanding helps elucidate the load-bearing process on piers, identify critical areas of maximum stress on piers for focused protection, or serve as a reference for extreme load calculations during the initial design of piers. This study aims to address these objectives.
Experimental Setup:
Please clarify the following points in details to better clear this section of manuscript:
- How to a carriage, chute, and landslide mass can simulate landslides? Give a sufficient explanation
Sorry for not explaining this point clearly in the manuscript. It has been added as a supplement in the manuscript.
The process of landslide-generated waves primarily involves the interaction between the landslide and the water body. Most landslides exhibit planar shapes such as fan-shaped, tongue-shaped, and elongated forms. For landslides with fan-shaped and tongue-shaped planar geometries, the contact surface between the solid mass and the flowing water is effectively rectangular. In contrast, for landslides with elongated planar geometries, the contact surface is also rectangular. Therefore, in this experiment, we chose to simulate landslides with an elongated planar shape, which led us to select a rectangular flume for modeling. In reality, the sides of the landslide mass should exhibit zero friction. To replicate this condition in our experiments, we left a 1 cm space on each side when positioning the sliding block, allowing us to place a smooth 1 cm-thick cement board. During the landslide process, friction between the block and the sliding surface can generate a smooth powdery layer. To simulate this, we applied fine clay as a base layer on the bottom plate before positioning the sliding block. This approach allows us to model both the interaction between the sliding block and the water body and the frictional losses incurred as the block descends. To facilitate adjustments in landslide angle and height, there are pulleys both in front and behind the sliding frame.
- Why you using iron to construct the carriage and chute? Give the unique characteristics which realize the iron among other metals
Previously, we used glass plates, which were prone to shattering during the landslide process. Plastic plates, on the other hand, were susceptible to deformation due to their lower rigidity, which could distort the actual landslide shape during the sliding process. Thick iron troughs, with their superior hardness and rigidity, remained unaltered and unaffected by the deformation of the landslide, ensuring the precision of our experiments.
- Explain how can chute's bottom plate simulate the sliding surface?
During the landslide process, friction between the boulders and the sliding surface generates a smooth layer of clay. In this study, before placing the boulders, we applied fine clay to the chute's bottom to simulate the sliding surface.
- Explain the following sentence clearly with dimensions (roughly): “the size of individual blocks was determined based on the degree of fissure development and the width of the fissures”
The rockslide body primarily consists of rock blocks, various structural surfaces (such as weak interlayers, fissures, faults, etc.), as well as voids and cavities between these blocks. There are two fundamental types of structural units within rock masses: structural surfaces and structural bodies. Structural surfaces can further be categorized as weak structural surfaces and hard structural surfaces, while structural bodies can be divided into block-like structural bodies and slab-like structural bodies. These components combine and arrange differently within rock masses, resulting in various types of rock mass structures. During the downslope movement of most rockslide bodies, they may disintegrate due to the pre-existing fissures within the rock mass. As the sliding velocity increases, the degree of disintegration intensifies. Consequently, the rockslide bodies are characterized by a disintegrated structural pattern. We conducted a survey of the fracture dimensions found in the reservoir area, the size of individual blocks was determined based on the degree of fissure development and the width of the fissures. To facilitate the placement of boulders, we designed them with dimensions of length : width : height = 3:2:1.
- Development of rock mass fissures （b）Rock mass sliding and fragmentation
Table 2. The dimensions of the landslide body blocks.
|
No. |
（m） |
（m） |
（m） |
|
A1 |
0.18 |
0.12 |
0.06 |
|
A2 |
0.15 |
0.10 |
0.05 |
|
A3 |
0.12 |
0.08 |
0.04 |
|
A4 |
0.09 |
0.06 |
0.03 |
|
A5 |
0.06 |
0.04 |
0.02 |
- What is the reason for using this range of density? i.e., 2.3-2.8 g/cm³?
The geological conditions in the Three Gorges Reservoir area are characterized by well-developed fractures within the rock formations. The rock structures are diverse, primarily composed of mudstone and sandstone. Sandstone typically exhibits a natural density ranging from 2.2 to 2.7 g/cm³, while mudstone ranges from 2.45 to 2.65 g/cm³. The average density of the rock formations commonly falls within the range of 2.3 to 2.8 g/cm³, and for modeling purposes, we have adopted an average density of 2.5 g/cm³ as the density parameter for the model sliding blocks.
- Could you please provide a detailed table listing the properties of the clay that were manipulated to achieve a density of 2.5 g/cm³ in this section.
Table 3. The properties of the clay.
|
Material |
Density (g/cm³) |
Composition |
Cohesion (kPa) |
Internal friction angle |
|
Sandstone |
2.20~2.70 |
Purple-red sandstone, siltstone, carbonate rock |
Cf=27~29kPa |
φf=21°~24° |
|
Mudstone |
2.45~2.65 |
Montmorillonite and illite |
Cr=10～25kPa |
φr=5.6°ï½ž11.9° |
|
Test stone |
2.50 |
Subclay with crushed rock fragments |
C=25KPa |
φ=20° |
- Figure 1 lacks clarity and should be replaced with a more suitable image, ideally positioned adjacent to its schematic diagram for a cohesive presentation.
Thank you for your suggestion. We have replaced the images with higher clarity figure. Placing them adjacent to the schematic diagrams caused a reduction in image size, potentially making it difficult for readers to discern details. As a solution, we have positioned the 3D water tank images nearby.
- All units of measurement must be standardized, using either (m) or (cm), consistently across figures, text, or any other relevant context.
Thank you for your professional guidance. We have made the necessary corrections as per your instructions.
Table 2. The dimensions of the landslide body blocks.
|
No. |
（m） |
（m） |
（m） |
|
A1 |
0.18 |
0.12 |
0.06 |
|
A2 |
0.15 |
0.10 |
0.05 |
|
A3 |
0.12 |
0.08 |
0.04 |
|
A4 |
0.09 |
0.06 |
0.03 |
|
A5 |
0.06 |
0.04 |
0.02 |
- This section should be accompanied by a clear image illustrating the '3D wave basin,' ideally placed adjacent to Figure 2 to facilitate showing them together.
Thank you for your suggestion. We have add the '3D wave basin'.
Figure 2. Experimental layout diagram（unit：m）.
- “The slopes on both sides are 20° and 33° respectively”, What is the justification for utilizing these angles? Provide a valid explanation
Thank you very much for your professional advice. Corresponding additions and changes have been made to the manuscript.
The experimental section was conducted in the Wanzhou section of the Three Gorges Reservoir area, where we conducted a detailed analysis of the river's topography, measured the dimensions and angles of river cross-sections, and designed the channel dimensions to closely match those of both straight and curved sections. The channel dimensions were designed based on the dimensions of a straight channel, and after scaling down according to a scale ratio of , the profile data statistics are presented in Table 4.
Figure 2. The cross-section for the Wanzhou section.
Figure 3. Cross-section dimension labeling.
Table 4. Profile data statistics
|
Location |
A/m |
B/° |
C/° |
D/m |
E/m |
F/m |
|
Straight |
1.16 |
33 |
20 |
1.79 |
2.94 |
3.27 |
|
Curve1# |
1.16 |
28 |
16 |
2.2 |
1.68 |
4.12 |
|
Curve 2# |
1.16 |
32 |
14 |
1.84 |
1.41 |
4.75 |
|
Curve 3# |
1.16 |
26 |
17 |
2.36 |
1.84 |
3.8 |
|
Curve 4# |
1.16 |
41 |
18 |
1.35 |
2.96 |
3.69 |
|
Curve 5# |
1.16 |
25 |
19 |
2.47 |
2.17 |
3.36 |
|
Curve 6# |
1.16 |
28 |
19 |
2.22 |
2.43 |
3.35 |
|
Curve 7# |
1.16 |
29 |
20 |
2.11 |
2.69 |
3.2 |
|
Curve 8# |
1.16 |
29 |
18 |
2.14 |
2.27 |
3.59 |
|
Curve 9# |
1.16 |
28 |
20 |
2.23 |
2.53 |
3.24 |
- This paragraph require sentences restructuring and an elucidation of the rationale behind utilizing these dimensions: “A bridge pier ……. The depth of the river channel was â„Ž, as illustrated in Figure 2”.
Thank you very much for your professional advice. Changes have been made as requested:
Within a 400 m range near the landslide point, protective measures will be implemented. This study focuses on the most dangerous state of the impact of landslides on bridge piers. Therefore, the bridge piers were placed 6 meters away from the landslide point, at an actual engineering distance of 420 m. The bridge pier on the same bank was located on the near side of the landslide, while the bridge pier on the opposite bank was located on the far side of the landslide.
A wave gauge (WG1) was placed at the landslide point to measure the initial wave height with an accuracy of 1 mm and acquisition frequency of 100 Hz. WG3 and WG5 were positioned 10 cm in front of the bridge piers. Placing them too close would affect the waves, while placing them too far would not capture the wave height in front of the piers. WG3 measures the wave height in front of the far-side pier, while WG5 measures the wave height in front of the near-side pier. WG2 was placed at the midpoint of the line connecting the landslide and the far-side pier, and similarly, WG4 was positioned at the midpoint of the line connecting the landslide and the near-side pier. The landslide had a width , a length , and a thickness , with an angle between the landslide and the water surface. The depth of the river channel was , as illustrated in Figure 4.
- Finally, this section must be included the % accuracy of the results obtained due to this set up with the real landslide.
I apologize for my answer. The design of the landslide dimensions and angles in this experiment is based on a generalized statistical analysis of over 50 rockslides in the reservoir area. It falls under a systematic study, and there are no corresponding real landslide cases for the test conditions. Therefore, we cannot provide a precise comparison between the test conditions and actual cases.
Forms and Distribution of Wave Pressure
- The author(s) present numerous results in this section, but the explanations are very simple and do not align with these findings. Therefore, it is essential to improve the explanations of this section, providing distinct explanations for each result.
Thank you for your professional guidance. This section has been rewritten.
In this paper, wave pressures can be categorized into two types: pulsating pressure (), and resonance pressure (). is characterized by low frequency, with an action period consistent with the wave cycle, frequency ranging from 0.2 to 0.5Hz. In the absence of wave reflection superposition, the first wave is the largest. The studied in this paper refers to the difference in pressure between the first wave peak and trough. is the pressure generated when the waves reach the bridge pier due to the resonance caused by the impact. It exhibits high-frequency and vigorous oscillations, with frequencies measured in the experiment ranging from 300 to 900Hz. The studied in this paper represents the maximum wave pressure obtained during the high-frequency vibration process induced by the wave impact on the bridge pier. To summarize, results from the pressure changes caused by the variations in the water surface during the wave action process, while arises from the resonance of the bridge pier due to the impact of the waves.
Since the dynamic wave pressures were consistently at zero before the wave arrives, for the purpose of differentiation on the graph, the initial values at each measurement point along the water depth were adjusted. When analyzing the condition of the opposite bank bridge pier at h=1.16m, it was found that the wave pressure time processes from to were entirely consistent, with identical waveforms. This consistency arises from the synchronicity of water particle motion along the water depth direction when waves approach the bridge pier. Prior to the occurrence of pulsating pressure (), there was a common presence of resonance pressure () at the same time. This pressure form exhibited high-frequency oscillations, with being both high-frequency and intense. The had a period that was completely synchronized with the wave period. This paper focuses on the analysis of the first wave pressure, with an approximate duration of 3 seconds during the first wave action.
It's worth noting that at the same position, using a wave pressure sampling frequency of 100Hz did not result in . After the data was sampled at 1000Hz and subjected to Fourier Transform Filtering (FTF), the waveform was nearly identical to the data sampled at 100Hz, validating the high-frequency nature of . As the water depth increases, the length over which the bridge pier experiences force also increases. Consequently, the total force acting on the bridge pier increases, leading to resonance during wave impact. However, due to the height limitations of the existing water tank, further research will be conducted to provide additional evidence and insights into wave pressures under conditions of higher water levels.
Figure 6. The time variation of pressure at measurement points on the opposite bank bridge pier in Case9.
The study was conducted to analyze wave pressures on bridge piers under three different operational water levels in the Three Gorges Reservoir area. The study investigates the temporal variations of wave pressure at the measurement points on the bridge piers under three different water depth conditions and compares them with the corresponding wave height variations measured by the WGs in front of the piers. Here, represents the wave pressure at measurement points on the opposite bank bridge pier, and represents the wave pressure at measurement points on the same bank bridge pier. As shown in Figure 7, it can be observed that under all water depth conditions during the experiment, the fluctuations in wave pressure and wave height exhibit a strong positive correlation. The variations in wave pressure along the water depth for each condition are consistent, indicating a close relationship between dynamic wave pressure on the entire bridge pier and wave height.
In various conditions, different wave profiles were generated. When comparing the wave height profiles in Figure 7(a),7(c), and 7 (e), it can be observed that the first two waves in Figure 7(a) are relatively regular, while the third wave suddenly increases in magnitude, followed by chaotic waveforms. In Figure 7(c) and 7(e), the second wave trough is larger, and subsequent waveforms are more chaotic. This variation can be attributed to the shallower water depth, which results in the bridge pier being closer to the slope, leading to shorter wave reflection and superposition times. Under the same operational condition, waveforms on the opposite side of the bridge pier (across from the slide) and on the same side of the bridge pier (along the slide) do not match, indicating significant differences in wave generation and propagation between the 3D water tank and the 2D flume. In the 2D flume, waveforms remain consistent along the cross-sectional profile, while in the 3D water tank, waveforms exhibit variations depending on the direction of generation
Figure 7(a) also shows a significant high-frequency oscillation before the onset of pulsating pressure. Pre-experiments were conducted before the actual test, where the bridge pier was anchored to the slope with concrete and the wave pressure measurement points were connected. Throughout the entire test process, there was no human intervention with the bridge pier and wave pressure measurement points. Therefore, it can be inferred that the influence of experimental equipment can be ruled out. Furthermore, this phenomenon was observed only on the bridge pier on the opposite side (across from the slide) when h=1.16 m. Han [1] divided the wave propagation direction into the main wave area and the secondary wave area. The main wave area extends within a 60° range from the landslide axis. The wave on the opposite side of the bridge pier falls within the main wave area, where the wave carries greater energy. In contrast, the bridge pier on the same side (along the slide) falls within the secondary wave area, where the wave carries less energy.
Figure 7. The wave pressure distribution on the same bank and opposite bank bridge piers at water depths of 0.74m, 0.88m, and 1.16m, as well as the wave height distribution in front of the bridge piers.
- All the diagrams in Figure 4 should be substituted with other clearer ones.
Thank you for your suggestion; all the figures in Figure 4 have been replaced with clearer ones as requested.
Figure 4. The wave pressure distribution on the same bank and opposite bank bridge piers at water depths of 0.74m, 0.88m, and 1.16m, as well as the wave height distribution in front of the bridge piers.
- The discussion section should be precisely integrated with the results portion, adequately elucidating each paragraph on its own.
Thank you for your suggestions; the discussion part has been rephrased.
In reference to and , The generation of is unquestionably due to wave action. However, represents a newly discovered force, and this study marks an initial exploration of . It was found that exhibits high-frequency and short-lived characteristics. Through analysis, it was hypothesized that results from the resonance of bridge piers induced by wave action, and it occurs primarily under conditions of greater water depth. Due to limitations in the experimental site, this study was unable to conduct tests under significantly greater water depths. Future research will aim to validate this hypothesis through more comprehensive experiments.
Regarding the forces exerted by waves, a recent study by TAN et al. [27] identified impact pressure and pulsating pressure. Impact pressure was found to be distance-dependent and associated with the jetflow when it reached pressure sensors, resulting in jetflow pressure (impact pressure). Pulsating pressure was observed when waves reached the opposite side and were measured on the pressure side plates. Except for impact pressure generated by jetflow, all other pressure variations recorded in the study were classified as pulsating pressure. The pulsating pressure investigated in this paper aligns with the focus of their study. It is essential to distinguish between resonance pressure () and impact pressure () in terms of their underlying causes. results directly from the impact of jetflow, while is linked to the resonance of bridge piers.
Figure 10. Jetflow and wave diagram
This study identified three different distribution patterns of along the water depth: no peaks, single peaks, and multiple peaks. However, due to limitations in experimental conditions and equipment, it was not possible to collect more detailed distribution data. Nevertheless, all peak distributions under various water depth conditions can be categorized within these three distribution patterns. The study also mentioned that smaller landslide volumes may result in larger peaks. This is because smaller volumes generate smaller wave heights, leading to relatively smaller values. As a result, the peaks appear larger. In the future, further research will be conducted to comprehensively investigate the impact of landslide parameters on .
experienced by the bridge piers is a contributing factor to their damage, and it's possible that may be more destructive than . Therefore, this experiment examined the relationship between and and found that .As discussed earlier, there is a positive correlation between and , as shown in Figure 8. An analysis and fitting resulted in Equation 1 with an R2 value of 0.78. In scenarios of engineering concern, the most dangerous situations were examined, considering that , , leading to the formulation of Equation 4.
Figure 11. Fitting of dimensionless wave pressure and wave height.
Figure 12. The relationship between and
(1)
(2)
(3)
(4)
where is the density of water, is the acceleration of gravity, is the maximum wave height in front of the pier, is the still water depth in water tank.
- Conclusions: This part needs to reformulate its sentences carefully, and clarify the findings of the manuscript obtained in a more comprehensible and convenient manner.
Thank you for your suggestions; the conclusion part has been rephrased.
- Conclusions
In this study, the 3D water tank test method was used to investigate the distribution of dynamic water pressure acting on the bridge. This study has made the initial discovery that wave pressures on the bridge piers under wave action can be categorized into resonance pressure and pulsating pressure. The main conclusions of this study can be summarized as follows:
(1) The pulsating pressure was generated due to wave action and exhibits a strong correlation with the wave height in front of the bridge piers. It has a frequency range of 0.2-0.5 Hz, which aligns with the wave frequency. The resonance pressure was induced by the resonance of the bridge pier and is characterized by high-frequency and intense oscillations. It occurs at frequencies ranging from 300 to 900 Hz. Notably, resonance pressure was observed only under the condition of the larger water depth, specifically at h=1.16 m. Moreover, it was limited to the bridge pier on the opposite side (across from the landslide).
(2) exhibits a sawtooth-like pattern along the water depth for the opposite bank bridge pier and remains relatively constant, while for the same bank bridge pier, it decreases in a sawtooth pattern along the water depth. tends to increase with larger landslide volumes and steeper landslide angles. Additionally, it reaches its maximum near the still water surface.
(3) The distribution pattern of along the water depth can be categorized into three types: multi-peak, single-peak, and none-peak. Large landslide volumes produce single-peak or none-peak distribution for , while smaller landslide volumes result in a double-peak distribution. In general, the trend along the water depth direction is an increase followed by a decrease. The maximum for all scenarios is consistently at (one-third of the water depth below the water surface), and (one-fifth of the water depth below the water surface) represents the second-largest . These two positions on the bridge pier are more susceptible to damage and should be prioritized for enhanced protection during design and maintenance.
(4) An equation for was derived through analysis and fitting. The comparison between and indicated that . Considering that .
- References (optional): If outdated references, older than a decade, are not essential, it is advisable to substitute them with more recent ones, (if feasible).
Partial references have been replaced.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript presents the results of experiments conducted in a tank mimicking the landslide generation of surface waves that will eventually hit structures (in this cases piles). The measured quantities are not many and, therefore, the presentation of the results is quite straightforward. I have two major comments for this manuscript.
First, the authors introduce four pressures (pulsating, resonance, impact and jetflow) without defining them and without explaining how they can be determined from measured signals, with the result that the provided arguments are not understandable.
Second, since it is (expectedly) mentioned that there is a relationship between wave height and resulting pressure, (1) this relationship may be better framed in the context of hydrodynamic pressure distributions and (2) a key issue can be posed on determining the wave height resulting from a certain landslide.
My recommendation is to return the manuscript to the authors for a major revision.
One thing that came to my mind from the very beginning of the abstract is this: a landslide-generated wave will impact everything in the reservoir, so why concentrating just on piers? Also at line 31, light is put on “the” bridge, but other items are also present. Motivation for specifically considering bridges would be needed. It is presently given in the last paragraph of the Introduction, but it must either come earlier or a mention to piers in the first line must be given later.
24: Y and h are not defined. I suggest avoiding these symbols in the abstract, I guess this can be replaced with “one third of water depth”.
79: in the last part of the Introduction, a short description of the manuscript content may be given to engage a reader.
118; would it be better writing the “first” wave instead of the “initial” one? Also based on the sketch of Fig 3, my understanding is that at every point there will be a Hm as the amplitude of the first wave.
121: not clear which averages these are. Temporal averages of the pressures measured at each point, I guess?
Figure 3: the pier on the same bank is longer than that on the opposite bank, but it was the opposite in Figure 2. Please clarify or fix.
Table 2: please define symbols in the caption and avoid using the / for measuring units.
161: did the measured pressures always follow a Stevin law? In case the answer was positive, this would indicate insignificant effect of dynamic processes, and just a hydrostatic pressure distribution determined by a variable water surface elevation. If not, an opposite interpretation would hold.
161-174: I think that these resonance and pulsating pressures need to be defined before arguing about them. How can one recognize them from the signals? Are they associated to different mechanisms? Is separating them worth, and why? This paragraph is in need of clarification.
Figure 6: P_pu is not defined. How is a single representative value computed from the signal of pressure at a certain measuring point? More in general, the paragraph 179-192 needs improvement for clarity.
193-194: a direct correspondence between landslide volume and wave pressure is indeed expectable. However, why is it discussed only for the last four cases?
205 and following: as for above, also P_re needs to be defined, or the associated paragraph will remain obscure.
223-224: here two more pressures come into play (“impact” and “jetflow” but they are not defined, making the text not understandable.
244: since resonance does not always occur, eq. (4) may be overconservative in the majority of cases. Can the authors argue on this?
Grammar/misprints
10: I suggest using “a” reservoir area.
55: has been
56: line needs to be fixed, as there is something missing or something in need of removal. Same at line 57.
64: Hager
95: Figure 2
99: A wave gauge was
112: was
114: this longitudinal direction is unclear and is, in my understanding, the vertical along the piers; some rephrasing will avoid confusion.
122: a “.” Is needed.
193-202: fix font.
230: ..
233: according to the text, figure 8 must contain a P_pu instead of a generic P.
255: used
As above.
Author Response
Response to Reviewer 2 Comments
Dear reviewer,
We appreciate the time and effort that you dedicated to providing the feedback on our manuscript and are grateful for the insightful comments on our paper. We can see that your comments are very pertinent and useful. Thank you for your comments. We have studied insightful comments and tried our best to revise the manuscript. We used red fonts to mark revisions, detailed review comments reply as follows:
The manuscript presents the results of experiments conducted in a tank mimicking the landslide generation of surface waves that will eventually hit structures (in this cases piles). The measured quantities are not many and, therefore, the presentation of the results is quite straightforward. I have two major comments for this manuscript.
First, the authors introduce four pressures (pulsating, resonance, impact and jetflow) without defining them and without explaining how they can be determined from measured signals, with the result that the provided arguments are not understandable.
Second, since it is (expectedly) mentioned that there is a relationship between wave height and resulting pressure, (1) this relationship may be better framed in the context of hydrodynamic pressure distributions and (2) a key issue can be posed on determining the wave height resulting from a certain landslide.
My recommendation is to return the manuscript to the authors for a major revision.
One thing that came to my mind from the very beginning of the abstract is this: a landslide-generated wave will impact everything in the reservoir, so why concentrating just on piers? Also at line 31, light is put on “the” bridge, but other items are also present. Motivation for specifically considering bridges would be needed. It is presently given in the last paragraph of the Introduction, but it must either come earlier or a mention to piers in the first line must be given later.
Thank you for your suggestion. Based on your suggestion, the Introduction has been adjusted and partially rewritten to make its meaning and purpose clearer.
Bridges are the most common transportation infrastructure in reservoir areas. Landslides in these regions can directly destroy bridges and roads along their paths. Furthermore, during the secondary wave propagation process, they can also damage or wash away bridge piers. Therefore, targeted protection and monitoring of bridge piers are essential. To achieve this, it is crucial to understand the mechanisms of wave action on bridge piers, including the types and forms of pressure on piers under wave action. This understanding helps elucidate the load-bearing process on bridge piers, identify critical areas of maximum stress on bridge piers for focused protection, or serve as a reference for extreme load calculations during the initial design of bridge piers. This study aims to address these objectives.
24: Y and h are not defined. I suggest avoiding these symbols in the abstract, I guess this can be replaced with “one third of water depth”.
Thank you for your suggestion. Better expression has been replaced.
（3）The distribution of along the water depth exhibits three forms: multi-peak, single-peak, and none-peak, with the maximum positions for all conditions of occurring at approximately one-third of the water depth from the surface (). Finally, predictive formulas for the maximum wave pressures are provided.
79: in the last part of the Introduction, a short description of the manuscript content may be given to engage a reader.
Thank you for your professional suggestion. The manuscript has been supplemented
In order to elucidate the mechanics of landslide-generated waves on bridge piers, this study conducted experimental simulations using a 3D water tank. We investigated the types and origins of wave pressures on bridge piers under landslide-induced waves, analyzed the distribution patterns of different wave pressure types, their interrelationships, and ultimately provided the location of maximum pressure and a formula for calculating the maximum pressure.
118; would it be better writing the “first” wave instead of the “initial” one? Also based on the sketch of Fig 3, my understanding is that at every point there will be a Hm as the amplitude of the first wave.
“first” is indeed easier to receive and understand than “initial”, and changes have been made in the manuscript. Your understanding is correct, H1=Hm, and there will be a Hm for each position.
121: not clear which averages these are. Temporal averages of the pressures measured at each point, I guess?
Sorry for not explaining it clearly here. We need to study the difference in wave pressure under the action of the first wave peak and trough, which is defined as the wave pressure, i.e. Ppu. The average value of Ppu at each pressure measurement point is taken through multiple experiments.
Figure 3: the pier on the same bank is longer than that on the opposite bank, but it was the opposite in Figure 2. Please clarify or fix.
Sorry for forgetting to replace the incorrect figure. Thank you for your careful and professional review. We have already made the replacement.
Table 2: please define symbols in the caption and avoid using the / for measuring units.
Thank you very much for your suggestion. Changes have been made to the manuscript.
161: did the measured pressures always follow a Stevin law? In case the answer was positive, this would indicate insignificant effect of dynamic processes, and just a hydrostatic pressure distribution determined by a variable water surface elevation. If not, an opposite interpretation would hold.
Stevin’s law . Our research indicates that it does not follow Stevin's law. The pressure at measurement points is composed of static water wave pressure and dynamic water wave pressure. We consider the static water wave pressure at each measurement point to be zero and only consider the impact intensity of dynamic water wave pressure. Our experiments have shown that the relationship between dynamic water wave pressure and wave height variations is not a simple linear one. When the wave height is extremely large, the rate at which dynamic water wave pressure decreases with increasing wave height becomes smaller. To address this, we plan to conduct further in-depth research in the future.
161-174: I think that these resonance and pulsating pressures need to be defined before arguing about them. How can one recognize them from the signals? Are they associated to different mechanisms? Is separating them worth, and why? This paragraph is in need of clarification.
Thank you for your suggestion. Your advice was very valuable, and we overlooked this point. It has been addressed and added to the manuscript.
In this paper, wave pressures can be categorized into two types: pulsating pressure (), and resonance pressure (). is characterized by low frequency, with an action period consistent with the wave cycle, frequency ranging from 0.2 to 0.5Hz. In the absence of wave reflection superposition, the first wave is the largest. The studied in this paper refers to the difference in pressure between the first wave peak and trough. is the pressure generated when the waves reach the bridge pier due to the resonance caused by the impact. It exhibits high-frequency and vigorous oscillations, with frequencies measured in the experiment ranging from 300 to 900Hz. The studied in this paper represents the maximum wave pressure obtained during the high-frequency vibration process induced by the wave impact on the bridge pier. To summarize, results from the pressure changes caused by the variations in the water surface during the wave action process, while arises from the resonance of the bridge pier due to the impact of the waves.
Figure 6: P_pu is not defined. How is a single representative value computed from the signal of pressure at a certain measuring point? More in general, the paragraph 179-192 needs improvement for clarity.
Thank you for your suggestion. It has been addressed and added to the manuscript.
is characterized by low frequency, with an action period consistent with the wave cycle, frequency ranging from 0.2 to 0.5Hz. In the absence of wave reflection superposition, the first wave is the largest. The studied in this paper refers to the difference in pressure between the first wave peak and trough.
193-194: a direct correspondence between landslide volume and wave pressure is indeed expectable. However, why is it discussed only for the last four cases?
Thank you very much for your question.
The distribution pattern under the maximum water depth condition of h=1.16m (C9-C12) discussed in this discussion is more general and has more measurement points under this water depth condition. Other working conditions have shallow water depths, and there are only three measurement points underwater at h=0.74m water depth. The obtained pattern is not representative, so it was not included in the manuscript for analysis.
205 and following: as for above, also P_re needs to be defined, or the associated paragraph will remain obscure.
Thank you for your suggestion. It has been addressed and added to the manuscript.
is the pressure generated when the waves reach the bridge pier due to the resonance caused by the impact. It exhibits high-frequency and vigorous oscillations, with frequencies measured in the experiment ranging from 300 to 900Hz. The studied in this paper represents the maximum wave pressure obtained during the high-frequency vibration process induced by the wave impact on the bridge pier.
223-224: here two more pressures come into play (“impact” and “jetflow” but they are not defined, making the text not understandable.
I'm sorry for not explaining it clearly in the manuscript, there is an explanation in the figure with “jetflow”, “jetflow pressure” also called “impact pressure”. It has been addressed and added to the manuscript.
Regarding the forces exerted by waves, a recent study by TAN et al. [30] identified impact pressure and pulsating pressure. Impact pressure was found to be distance-dependent and associated with the jetflow when it reached pressure sensors, resulting in jetflow pressure (impact pressure). Pulsating pressure was observed when waves reached the opposite side and were measured on the pressure side plates. Except for impact pressure generated by jetflow, all other pressure variations recorded in the study were classified as pulsating pressure. The pulsating pressure investigated in this paper aligns with the focus of their study. It is essential to distinguish between resonance pressure () and impact pressure () in terms of their underlying causes. results directly from the impact of jetflow, while is linked to the resonance of bridge piers.
Figure 8. Jetflow and wave diagram
244: since resonance does not always occur, eq. (4) may be overconservative in the majority of cases. Can the authors argue on this?
Thank you for your suggestion. The manuscript has already been added.
This study identified that the occurrence of is associated with a water depth of 1.16 m (which would occur under actual engineering conditions at 81.2 m). However, using the same formula for calculations in all conditions may not be appropriate. Therefore, it is necessary to establish suitable conditions for applying this formula.
when ,
when ,
Grammar/misprints
10: I suggest using “a” reservoir area.
55: has been
56: line needs to be fixed, as there is something missing or something in need of removal. Same at line 57.
64: Hager
95: Figure 2
99: A wave gauge was
112: was
114: this longitudinal direction is unclear and is, in my understanding, the vertical along the piers; some rephrasing will avoid confusion. ” In the water depth direction”
122: a “.” Is needed.
193-202: fix font.
230: ..
233: according to the text, figure 8 must contain a P_pu instead of a generic P.
255: used
Thank you very much for your careful review; each item has been revised.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Author(s)
The required modifications are conducted.
Author Response
Thank you very much for your review work
Reviewer 2 Report
I see that the authors have accounted for the comments made on a previous version. I recommend acceptance after minor revisions (see some sticky notes in the attached pdf file).
Comments for author File: 
Comments.pdf
Some moderate revision would be needed.
Author Response
Cover Letter
Dear reviewers,
Thanks for your letter and for reviewers comments concerning our manuscript entitled “Pressure characteristics of landslide generated waves on bridge pier”(ID: water-2622936). Those comments are all valuable and helpful for revising and improving our paper. We have studied all comments carefully, and have made conscientious correction. Revised portion are marked Yellow highlight mark. We tried our best to improve the manuscript and made some changes in the manuscript. We appreciate for reviewers warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.
Q1: I suggest using "In a reservoir area"
Q2: Invert, Ppu first and Pre second (as in the above sentence).
Q3: corresponds
Q4: "structures" instead of "bridges". Specific mention to bridges will come at line 63
Q5: the first lines of this paragraph are basically a repetition of 63-69; I suggest to remove some content from here to avoid repetition
Content has been removed.
Q6: A mention to fig 4 comes before mentions to figs 2 and 3; the order of figures may be changed to have a straightforward reading
The image order has been changed
Q7: In this figure the basin seems prismatic in section, while it would not be according to figure 2 and table 4. please clarify
Q8: first
Q9: It is
Author Response File: Author Response.docx
