Reinforced Soil Retaining Wall Research Articles

Enhancements in image quality and block detection performance for Reinforced Soil-Retaining Walls under various illuminance conditions

To ensure continuous monitoring of reinforced soil-retaining walls (RSWs) even under low-illuminance conditions, such as during the night, it is imperative to evaluate the performance of deep learning-based detection. In this study, we constructed a laboratory RSW model and generated a dataset with varying illuminance levels to assess the impact of image enhancement and block detection. Various image enhancement methods were applied to improve image quality and evaluate their effect on deep learning. RGB optimization (RO) was proposed to optimize RGB intensity and compared with gamma correction, histogram equalization, and low-light image enhancement with illumination map estimation. RO demonstrated outstanding image enhancement performance, as evidenced by lightness order error, peak signal-to-noise ratio, and structural similarity index measure, ensuring high image quality. The trained RO model using Mask R-CNN exhibited excellent accuracy, recall, and F1 score, delivering remarkable detection performance under low illuminance conditions, resulting in a 7.44 % improvement in the F1 score. Image enhancement techniques that maintain similarity, such as lightness order error and structural similarity, across varying illuminance conditions contribute to enhancing the block detection performance of Mask R-CNNs.

Dynamic Characteristics of Reinforced Soil Retaining Wall with Composite Gabion Based on Time Domain Identification Method

A series of shaking table tests was carried out on the dynamic performance and working mechanism of a gabion reinforced soil retaining wall under seismic load. The test results show that the panel presents the deformation mode of middle and upper bulging at the contact point between the rigid box and the retaining wall The settlement of top backfill is relatively uniform, and there is basically no differential settlement, the natural frequencies at different positions and heights inside the retaining wall are basically the same, and the natural frequencies are stable between 22.61 and 23.04 Hz below 0.8 g. The damping ratio decreases with the increase in wall height, and the damping ratio at each stage after vibration is greater than that before vibration. The seismic earth pressure is nonlinearly distributed. The measured value of the lower part of the retaining wall is smaller than that calculated by the Seed–Whitman method with an increase in peak acceleration, and the measured value of the upper part of the retaining wall is larger than the theoretical calculation results. The position of the resultant action point of seismic earth pressure is greater than 0.33 times the wall height specified by the Mononobe–Okabe method.

Model Test and Numerical Simulation Research of Reinforced Soil Retaining Walls under Cyclic Loads

The stress diffusion characteristics of reinforced soil retaining walls (RSW) with concrete-block panels under cyclic loads are studied. The distribution of the vertical dynamic earth pressure caused by an external load and the analysis of stress diffusion angles were studied using a model test and the numerical simulation model of the reinforced soil retaining wall was established to analyze the change in the stress diffusion angle. We then changed the parameters to investigate the influencing factors of the stress diffusion characteristics. The results showed that: the average value of the peak vertical dynamic earth pressure caused by an external load at the loading position of the RSW was a nonlinear distribution, decaying from top to bottom and increasing with the increase in the loading amplitude, while the change in the loading frequency number of loading cycles had no obvious rule. The results of model test and numerical simulation agree with each other. The diffusion angle of the stress caused by the external load of the reinforced body was basically between 50° and 65° in the range from 1.8 m to 1.2 m, the diffusion angle at the top was slightly larger than the middle, and the diffusion angle away from the wall was larger than the diffusion angle close to the wall. The main factors affecting the stress diffusion in reinforced soil retaining walls are the coefficient of reinforcement of the soil and the dynamic stress amplitude; the stress diffusion angle increased with an increase in the coefficient of the reinforcement of the soil and the dynamic stress amplitude. The conclusion of this paper can provide a reference for the design of reinforced soil structures.

Numerical and Analytical Analysis of the Surcharge Application Distance influence on the Behavior of Reinforced Soil Retaining Wall

Numerical and Analytical Analysis of the Surcharge Application Distance influence on the Behavior of Reinforced Soil Retaining Wall

Analysis of the Working Response Mechanism of Wrapped Face Reinforced Soil Retaining Wall under Strong Vibration

A series of shaking table tests were carried out to explore the dynamic characteristics and working mechanisms of wrapped-face reinforced soil-retaining walls under strong vibration. Under the 0.1–1.0 g horizontal peak ground acceleration (HPGA), the damping ratio of sand shows a downward trend as a whole, so the acceleration amplification coefficient decreases with the increase of HPGA. However, when HPGA reaches 1.0 g, the acceleration amplification coefficient increases; the range of acceleration amplification coefficient at the top of the wall is 1.69–1.36. When HPGA is 1.0 g, the maximum cumulative residual displacement of the panel is 2.96% H, and the maximum uneven settlement of the sand is 3.57% H, both of which have exceeded the limit of the specification. With the increase of HPGA, the ratio of the dynamic earth force increment to the total dynamic earth force gradually approaches 50%. Since the reinforcement effect of geogrid is not considered, the predicted value of traditional earth pressure theory is different from the measured value. According to the Washington State Department of Transportation displacement index, the deformation range of wrapped-face reinforced soil-retaining walls is divided into three stages: the quasi-elastic stage, the plastic stage, and the failure stage.

Performance Evaluation of Feature Matching Techniques for Detecting Reinforced Soil Retaining Wall Displacement

Image registration technology is widely applied in various matching methods. In this study, we aim to evaluate the feature matching performance and to find an optimal technique for detecting three types of behaviors—facing displacement, settlement, and combined displacement—in reinforced soil retaining walls (RSWs). For a single block with an artificial target and a multiblock structure with artificial and natural targets, five popular detectors and descriptors—KAZE, SURF, MinEigen, ORB, and BRISK—were used to evaluate the resolution performance. For comparison, the repeatability, matching score, and inlier matching features were analyzed based on the number of extracted and matched features. The axial registration error (ARE) was used to verify the accuracy of the methods by comparing the position between the estimated and real features. The results showed that the KAZE method was the best detector and descriptor for RSWs (block shape target), with the highest probability of successfully matching features. In the multiblock experiment, the block used as a natural target showed similar matching performance to that of the block with an artificial target attached. Therefore, the behaviors of RSW blocks can be analyzed using the KAZE method without installing an artificial target.

Determination of the Effect of Sidewall Friction in Reinforced Soil Retaining Wall Experiments

Abstract A simple approach to estimate sidewall friction in reinforced soil model experiments conducted in parallel-sided test boxes with unlubricated walls is proposed. Analytical solutions are developed for reinforced soil slopes and retaining walls subjected to self-weight or external loading. It turns out that the frictional effect depends on the shape of the failure zone and the value of friction coefficient between soil and a sidewall material. The theoretical predictions were verified in laboratory experiments in a test box with lubricated and unlubricated sidewalls. It was shown that the method can be used to estimate sidewall friction not only under failure conditions, but also under all stages of surcharging prior to failure.

Performance of Back-to-Back Geogrid Reinforced Soil Retaining Walls for Railways during Service

To investigate the performance of a reinforced soil retaining wall during service for a passenger-dedicated railway, long-term remote observation testing of the back-to-back geogrid reinforced retaining wall (BBGRSW) of Qing-Rong passenger-dedicated railway in Shandong Province was conducted for 60 months. The performance of the reinforced retaining wall was investigated after construction, and the lateral earth pressure of the reinforced soil wall was analyzed. The vertical stress on the wall and tension on the geogrid were measured using pressure cells and flexible deformation gauges, thereby resulting in the distribution of data and changes in the service period. The test results show that the pressure and deformation of the wall are almost stable. It was determined that the lateral earth pressure on the back of the wall panel was approximately 119.2% of the completion time during the 60 months after construction. The vertical stress on the reinforced soil retaining wall remained approximately stable 60 months post-construction. The maximum strain of the measured geogrids accounted for less than 30% of the peak strain. Moreover, the deformation of the wall was relatively small, which indicated that both sides of the wall remained in good condition. These research results can serve as a reference for the design optimization of reinforced soil retaining walls for high-speed railways.

Shaking Table Study on the Seismic Performance of Geogrid Reinforced Soil Retaining Walls

This study presents experimental results from shaking table tests on a reduced-scale geogrid reinforced soil retaining wall (RSRW) to investigate the seismic response of the fundamental frequency, acceleration amplification, face displacement, backfill surface settlement, and reinforcement strain under different peak accelerations and durations. The fundamental frequency is in good agreement with the predicted values. The root mean square (RMS) acceleration amplification factors increase nonlinearly with the wall height and decrease with increasing seismic load, which is not regarded as a constant value. The distributions of the peak displacement are consistent with those of the residual displacement. The combination of the sliding and rotation is observed as the predominant mode of displacement, and the rotation mode is dominant. The positions near the face (35 cm) and the ends of the reinforcement (140 cm) demonstrated larger settlement than that of the central position (70 cm and 105 cm). The reinforcement strain increased with increasing peak acceleration and maximum values measured at the central layers. The trends of the potential failure surface are similar to those of the 0.3H bilinear failure surface. The friction coefficient is nonlinearly distributed along with the reinforcements, and the maximum friction coefficient appears at the top layer (F11).

Dynamic Response of Reinforced Soil Retaining Wall Resting on Soft Clay

Dynamic Response of Reinforced Soil Retaining Wall Resting on Soft Clay

Model studies on polymer strip reinforced soil retaining walls

Polymer strip (PS) reinforced soil retaining walls (RSRW) are in common use due to the associated construction speed, ease of use, aesthetic appeal and low cost. It is quite significant to estimate the deformation behavior of this types of walls before construction. In this study, firstly, a full-scale field model of PS-RSRW was constructed and instrumented. According to the experimental result, the maximum measured displacements occurred at 30% of the height down from the top of the wall. The maximum tensile loads in the reinforcements were measured at a distance of 40% of the wall height from the face of the wall. Then, a two-dimensional (2D) finite element method (FEM) model was established and calibrated with experimental data from the field model. The predicted displacements of the wall facing showed reasonable agreement with the measured deformations. The reinforcement loads calculated from the validated FEM model were also compared with theoretical methods. Finally, RSRW having different heights were numerically modeled with various combinations of materials utilized for filling and reinforcement. The effects of parameters such as wall height (H), reinforcement length (L) and reinforcement interval (Sv) on the horizontal wall displacement and on the reinforcement loads are investigated through parametric analyses.

Monitoring Technique Using a Vision-based Single-Camera System for Reinforced Soil Retaining Wall

Reinforced soil retaining walls are widely applied, and their frequency of collapse increases along with their use. Safety inspections are regularly conducted to ensure the structural safety of such walls. However, unexpected collapses occur for different reasons, such as design and construction problems, maintenance issues, and natural disasters including intensive rainfall. In this study, a single-camera system is proposed to evaluate the behavior of a retaining wall based on a single-perspective image. Various feature matching methods were compared to determine the optimal method for monitoring the retaining wall structure. The behaviors of the retaining wall structure were analyzed using the optimal method. The results indicate that the KAZE method provides the best results for monitoring the behaviors of a retaining wall, with errors ranging from 0.03% to 7.37%. The proposed single-camera system is widely used to evaluate the stability of a structure with high accuracy.

Lateral displacement control of modular-block reinforced soil retaining walls under horizontal seismic loading

This paper presents experimental results from shaking table tests on two reduced-scale geogrid reinforced soil retaining wall (RSRW) constructed using standard soil, modular facing blocks, and uniaxial geogrid reinforcement to investigate the distribution of the lateral displacement, observe the failure mode of the RSRW, and analyse the lateral displacement control index under seismic loading. Similitude relationships for shaking table tests in a 1 g gravitational field were used to scale the specimen geometry and characteristics of the earthquake motions. The displacement modes of two RSRW are combined translation and rotation. Considering various displacement control indexes and the test results, a lateral displacement control index of 3.8% H in seismic damage of modular-block RSRW is proposed. The seismic damage-assessment criteria of the modular-block RSRW are defined and divided into four levels: basically intact, slightly damaged, moderately damaged, and destroyed.

Reinforcement Strain and Potential Failure Surface of Geogrid Reinforced Soil-Retaining Wall under Horizontal Seismic Loading

This paper presents experimental results from shaking table tests on two reduced-scale geogrid reinforced soil-retaining walls (RSRWs) constructed using standard soil, modular facing blocks, and uniaxial geogrid reinforcement to investigate the distribution of the geogrid strain and the mode of potential failure surface for dynamic loading conditions. Similitude relationships for shaking table tests in a 1 g gravitational field were used to scale the specimen geometry, applied characteristics of the earthquake motions. The lateral displacement of the top model is sufficiently large for the top-model block to fall down, and the RSRW is thus destroyed. The tensile strain at the lower part is greater than that at the upper part of the RSRW. The tensile strain in different layers for two-tiered RSRW is consistent with single-step RSRW. On comparing the measured maximum tensile strain lines of the geogrid with the result of the existing calculation method of the potential failure surface, it can be observed that the existing partial calculation method is conservative. Based on the calculation methods of various potential failure surfaces and the measured data, the use of a two-tiered fold-line failure surface is proposed for the two-tiered RSRW while taking into consideration the width of the platform. And it is advised that the failure surface calculation method of BS8006 be used as the calculation method for the potential failure surface of the single-step RSRW under dynamic motion.

Design Theory and Method of Geo-Synthetic Reinforced Soil Retaining Wall Combined with a Gravity Retaining Wall or Full Height Rigid Facing

Geo-synthetic reinforced soil retaining wall (GRS-RW) combined with a Gravity Retaining wall (GRW) facing or Full High Rigid (FHR) facing is a new type of retaining wall. This type of retaining wall is used to get full advantages of GRW and reinforced soil retaining wall (RS-RW) and to avoid their drawbacks. The design method based on the principle of working strain considers the backfill in the limit state but the reinforcement not in the limit state; while in traditional design method based on the tensile strength of reinforcement, consider both backfill and reinforcements in the limit state and it cannot reflect the influence of reinforcement stiffness. In this paper, numerical analyses were performed to evaluate the stress and strain of both reinforcement and backfill. From the analyses, deformation of the retaining wall, the working performance of GRS-RW with GRW facing, and contribution of geo-grids to GRS-RW with a GRW facing, were evaluated. Analyses are performed for determining the force between GRS-RW with a GRW facing and reinforced soil. Analytical methods, for the calculation of soil pressure acting on the back of GRW, based on the principle of working stress are obtained by comparative analysis between the working performance characteristics of common GRS-RW and GRS-RW with GRW facing. A new analytical method for determining the force between GRS-RW with a GRW facing and reinforced soil “E” is proposed. By comparative study between theoretical and numerical analysis results, method 1 and method 2 are recommended for determining the “E”. A method for determining the tension in the reinforcement of GRS-RW with a GRW facing based on the principle of working strain is also presented in this paper.

Dynamic behaviour of reinforced soil retaining wall under horizontal seismic loading

Based on the status that the reinforced soil retaining wall (RSRW) is difficult to popularize in highway in high earthquake intensity region of China. The dynamic behavior of modular-block RSRW was investigated by large-scale shaking table tests. The standard soil was taken as the backfill. The concrete blocks were selected as panel. The geogrid was reinforcement. The failure mode of the wall was observed, and dynamic response and the displacements were measured. The results showed that, the middle of retaining wall panel was slightly bulged under the inputted earthquake motion, the mortar on the surface of wall was breaking down. When the input motion was WL2.0g (model scale: 1/2), the blocks at the top fell down, then the retaining wall was destroyed. The settlements of the soil and lateral displacement of the wall increased with the increase of the acceleration motion. The acceleration amplification factor is decreased with the increase of input acceleration. When the input acceleration was larger than 0.8g, the acceleration amplification factor of upper wall gradually is decreased less than 1. When model scale and inputting earthquake motion is different, the range of acceleration amplification factor is different. Shaking table tests results of RSRW with different panel forms and reinforced materials are summarized. The results show that seismic behaviour of RSRW is excellent. It is advise to revise some items of “Chinese Specification of Seismic Design for Highway Engineering” in order to promote the application of RSRW in highway.

Effect of Acceleration on Wrap Faced Reinforced Soil Retaining Wall on Soft Clay by Performing Shaking Table Test

This research incorporates shaking table testing of scale wrap faced soil wall models to evaluate the seismic response of embankment. Currently the seismic designs of highway or railway embankment rely on little or no empirical data for calibrating numerical simulations. This research is working towards filling that empirical data gap. The specific purpose of the study was to evaluate the seismic response of constructed embankment model regarding the different input base accelerations with fixed frequency. A series of one-dimensional (1D) shaking table tests (0.05g, 0.1g, 0.15g and 0.2g), were performed on a 0.4 meters high wrap faced reinforced-soil wall model. Additionally, it was placed over 0.3 meters high soft clayey foundation. Predominantly, the influence of the base acceleration on the seismic response was studied in this paper. The physical models were subjected to harmonic sinusoidal input motions at a fixed frequency of 1 Hz, in order to assess the seismic behavior. The effects of parameters such as acceleration amplitudes and surcharge pressures on the seismic response of the model walls were considered. The relative density of the backfill material was kept fixed at 60%. The results of this study reveal that input accelerations and surcharge load had significant influence on the model wall, pore water pressure, and changes along the elevation. Acceleration response advances with the increase in base acceleration, so the difference being more perceptible at higher elevations. The pore water pressures were found to be high for high base shaking and low surcharge pressures at higher elevations. The results obtained from this study are helpful in understanding the relative performance of reinforced soil retaining wall under different test conditions resting on soft clay.

Behaviour Analysis of Reinforced Soil Retaining Wall According to Laboratory Scale Test

Reinforced soil retaining wall are ground structures that can be readily seen all around us. The development of reinforcements to these walls and their demand have increased rapidly. These walls are advantageous because they can be used not only in simple construction compared with reinforced concrete retaining walls but also when the height of the wall needs to be higher. However, unlike reinforced concrete retaining walls, in which the walls are integrated and resist the earth pressure on the back, the block-type reinforced earth retaining wall method secures its structural stability by frictional force between the buried land and reinforcements. A phenomenon in which a block is cracked or dropped owing to deformation has been frequently reported. In particular, this phenomenon is concentrated at the curved parts of a reinforced soil retaining wall and is mainly known as a stress concentration. However, to date, the design of reinforced soil retaining walls has been limited by the two-dimensional plane strain condition and has not considered the characteristics of the curved part. There is a lack of research on curved part. Therefore, this research determines the behavioural characteristics of curved-part reinforced soil retaining walls with regard to the shape (convex or concave) and angle (60°, 90°, 120°, and 150°). The displacement generated in the straight part and the curved part was analysed through an Laboratory Scale Test. The results showed that the horizontal displacement of the curved part increases as a convex angle becomes smaller, and the horizontal displacement of the curved part decreases as a concave angle becomes smaller. At the center (D and H have the same length, but H represents the height and D represents the separation distance from the center of the curved part) of the convex curve, the horizontal displacement of the 0.5 D section decreased to 13.8%; it decreased to 41.0% in the 1.0 D section. For concave angles, it was revealed that the horizontal displacement from the center 0.0 D to the 0.5 D section of the curved part increased by 25%, and from the 1.0 D section, by 75%. It was confirmed that the displacement difference was largely based on the value of 0.5 D. It was judged that this can be used as basic data for the design and construction guidelines for reinforced soil retaining wall of reinforced soil retaining walls.

Shaking table tests on reinforced soil retaining walls subjected to the combined effects of rainfall and earthquakes

Earthquakes and rainfall often occur together, and their combined effects on reinforced soil retaining walls (RSRW) are not investigated in detail. In this paper, shaking table tests were carried out in model-scale to investigate seismic performance of RSRW subjected to the combined forces of rainfall and earthquakes. Five cases with different degrees of saturation for the model ground were considered for comparison and each wall was shaken by a horizontal motion with a peak acceleration of 0.5 g. Various mechanical quantities, such as wall deformation, horizontal and vertical effective earth pressures, pore water pressure, horizontal acceleration and reinforcement strain were monitored carefully. It was found that wall displacement and reinforcement strain at naturally dry and saturated states are larger than those at unsaturated state, meaning that suction does have an enhancement effect on the seismic performance of RSRW. Furthermore, a special film force sensor that can measure effective pressure in saturated ground accurately was used to measure the effective earth pressure along the facing panel of RSRW, based on which, the seismic performance was discussed in a systematical way.

Discrete element analysis of structural characteristics of stepped reinforced soil retaining wall

Based on the laboratory large scale model test of the stepped reinforced soil retaining wall (RSRW), the discrete element numerical model of stepped RSRW is set up by particle flow code. The displacement of particles, stress distribution, force chain distribution, and potential failure surface of the stepped RSRW are analyzed by simulating the loading process. The results show that the geogrid can confine the horizontal displacement of soil and reinforce soil effectively. The geogrid endures the soil pressure of upside and transmits the pressure to surrounding soil, and improves the distribution of vertical soil pressure of the stepped RSRW. The number of strong force chains in the reinforced area is obviously higher than in the unreinforced area, which verifies that the geogrid can strengthen the soil. The soil particles have been in a plastic flow state and formed a continuous sliding surface at the front of retaining wall, but there was no obvious crack in the retaining wall. The potential failure surface of the stepped RSRW can be determined by observing the changes of force chain structure. The numerical simulation result of the potential failure surface is in good agreement with the theoretical calculation.