Settlement Of Soft Ground Research Articles

A Study on Developing a Model for Predicting the Compression Index of the South Coast Clay of Korea Using Statistical Analysis and Machine Learning Techniques

As large cities are continually being developed around coastal areas, structural damage due to the consolidation settlement of soft ground is becoming more of a problem. Estimating consolidation settlement requires calculating an accurate compressive index through consolidation tests. However, these tests are time-consuming, and there is a risk of the test results becoming compromised while preparing and testing the specimens. Therefore, predicting the compression index based on the results of relatively simple physical property tests enables more reliable and accurate predictions of consolidation settlement by calculating the compression index at multiple points. In this context, this study collected geotechnical data from the soft ground of Korea’s south coast. The collected data were used to construct a dataset for developing a compression index prediction model, and significant influencing factors were identified through Pearson correlation analysis. Simple and multiple linear regression analysis was performed using these factors to derive regression equations, and compression index prediction models were developed by applying machine learning algorithms. The results of deriving the significance of the influencing factors from the developed compression index prediction model showed that natural water content was the most significant factor in predicting the compression index. By collecting a significant amount of high-quality data and using the compression index prediction model and the model construction process proposed in this study, more accurate predictions of the compressive index will be possible in the future.

A Novel Approach to Determine the Treatment Range of Prefabricated Vertical Drains and Cement‐Soil Mixing Piles for Wide and High Embankment on Soft Ground

AbstractWide embankments with a width of tens or even hundreds of meters change the settlement distribution mode of soft ground. At the same time, the influence of embankment height on the stability and settlement of soft ground is quite significant. For the wide and high embankments, when the prefabricated vertical drain (PVD) is applied in the middle of the embankment and the cement‐soil mixing pile (CSMP) is implemented on both sides of the embankment, a novel determination approach of the reasonable proportion of the suitable treatment range of the PVD and the CSMP is proposed in this study. Combined with the engineering example of the Sanya Station yard of Hainan East Ring Railway, the Plaxis 2D finite element program is used to carry out the parameter analysis on the different proportions of PVD and CSMP in treatment ranges. It is confirmed that the proportion of the PVD and the CSMP in this project is between 2:3 and 4:1, which is consistent with the final design scheme provided by the design company. The on‐site monitoring results of this site show the effectiveness of the determination approach proposed in this paper.

Evaluation of UAV LiDAR Survey for Detecting Soft Ground Settlement at Construction Site in Coastal Area of Korea

Evaluation of UAV LiDAR Survey for Detecting Soft Ground Settlement at Construction Site in Coastal Area of Korea

Application of Drone LiDAR Survey for Evaluation of a Long-Term Consolidation Settlement of Large Land Reclamation

Drone surveys are gaining popularity for many construction applications, including in the fields of civil engineering, such as road construction, earthwork, structure monitoring, and coastal topography analysis. Drone surveying has a high potential for periodical long-term ground settlement measurement in the field of geotechnical engineering. Traditionally, manual measurement has been performed for limited points with controlled surface measurement points, but drone surveying may enable automated and periodical measurement for a wide and remote site. However, the accuracy of the elevation measurement and the surface settlement prediction has not been investigated, and the use of drone surveying has thus been limited. Therefore, an experiment was carried out to apply drone LiDAR (Light Detection and Ranging) surveying for soft ground settlement measurement at a large land reclamation site showing a very large settlement up to 10 m. Periodic drone LiDAR surveying was conducted, and the data were processed with direct georeferencing and with outlier removals (such as trees and construction vehicles) in order to generate a clean surface point cloud. We then compared the processed elevation data with ground control data to check the vertical accuracy and to predict the settlement as well as for consolidation. The drone LiDAR survey showed 13 cm, 42.9 cm, and 6.23% differences in RMSE (Root Mean Square Error) in terms of vertical accuracy, predicted long-term settlement, and consolidation, respectively. The drone LiDAR accuracy seems very useful for monitoring settlement over a large and remote land reclamation site of soft ground, showing settlement up to several meters where, without a surface measurement, installment is limited.

A New Calculation Method for Life Cycle Settlement of Soft Ground with Creep Treated by Columns

A New Calculation Method for Life Cycle Settlement of Soft Ground with Creep Treated by Columns

ASSESSMENT OF INFLUENCE OF BEARING CAPACITY OF SOIL BY GROUTING

This project work is on assessment of influence of bearing capacity of soil by grouting. From the early days of simple slurry injection to current sophisticated techniques, grouting has played, and continues to play, an important role in remediation and new construction World Wide. As new grouting technology is developed, and existing technologies are refined, the range of applications increases. Soil improvement is carried out for various objectives to improve bearing capacity and reduce settlement of soft ground, control ground water, stabilize excavation bottom, prevent deformation of surrounding ground, clean up contaminated ground and avoid or minimize earthquake liquefaction – induced soil deformations and associated damage. Grouting is the most common technical method used for soil improvement and strengthening. The grout is based on cement, silicate, or other materials, selected to suit particular ground conditions and improvement objectives. The very low bearing capacity of the foundation bed because shear failure and excessive settlements. Further, the high water table and limited depth of the top sandy layer in these areas restrict the depth of foundation thereby further reducing the safe bearing capacity. This paper discusses grouting as one of the possible solutions to the foundation problems of coastal areas by improving the properties of soil at shallow depths. This project presents an experimental procedure for how to improve the bearing capacity of soil. The bearing capacity of sandy soil samples are improved with respect to w/c ratio 1:3, 1:6 respectively. The sample was collected and are subjected to various test. In relation to the subject matter, view of some scholars& authors were reviewed and data presented and analyzed. Conclusions are made at the end of this project Index Terms –– sieve analysis, specific gravity, proctor compaction test, grouting, direct shear test

Evaluation of Asaoka and Hyperbolic Methods for Settlement Prediction of Vacuum Preloading Combined with Prefabricated Vertical Drains in Soft Ground Treatment

This study evaluated the use of the Asaoka and hyperbolic methods to estimate the ultimate settlement of soft ground treated by vacuum preloading combined with prefabricated vertical drains. For this aim, a large-scale physical laboratory model was constructed. The model was a reinforced-tempered glass box containing a soil mass with dimensions of 2.0 × 1.0 × 1.2 m (length × width × depth). Physical models of this scale for the same purpose are rare in the literature. The soil was taken from a typical coastal region in Dinh Vu Hai Phong, Vietnam. The surface settlement near and between the two drains was measured right after the vacuum preloading started. Important properties of the soil were tested to evaluate the effectiveness of the treatment method. The measured settlement was used in the Asaoka and hyperbolic methods to predict the potential ultimate settlement. The results showed the superiority of the vacuum consolidation approach in improving fundamental engineering properties of soft soil. Furthermore, the ultimate settlement predicted by both methods showed a good agreement with the measured value, proving that the Asaoka and hyperbolic methods are suitable for the estimation of the ultimate settlement of soft soil treated with vacuum consolidation.

Analysis of Settlement Behaviour of Soft Ground Under Wide Embankment

An elastoplastic numerical model for calculating the consolidation settlement of wide embankment on soft ground is established using PLAXIS finite element software to investigate the settlement behaviour of soft ground under the wide embankment. The distribution rules are analysed and compared to narrow embankments, such as surface settlements of ground and embankment, lateral displacement of soft ground at the foot of embankment slope and excess pore pressure in soft ground. The influence rule of elastic modulus of soft ground on the settlement of soft ground under wide embankment is discussed. The results show that the settlement distributions of wide and narrow embankments on soft ground are “W” and “V” shapes, respectively. The maximum settlement of wide embankment is near the foot of the embankment slope, which is unequal to the settlement at the centreline of the embankment. The lateral displacement distribution rules of soft ground are both “belly” shaped at the foot of two types of embankments slope. However, the lateral displacement of the wide embankment is larger in each corresponding stage. During the construction period, the excess pore pressure in the soft ground under the wide embankment is much higher than that of the narrow embankment, so the post-construction consolidation time of the wide embankment is longer. Moreover, the macroscopic settlement rule of the wide embankment is still the same with the increase of elastic modulus of soft ground.

Research on HC-LSSVM Model for Soft Soil Settlement Prediction Based on Homotopy Continuation Method

Prediction of soft soil settlement is an important research topic in the field of civil engineering, and the least square support vector machine is one of the commonly used prediction methods at present. Nonetheless, the existing LSSVM models have problems of low search efficiency in the search process and lack of global optimal solution in the search results. In order to solve this problem, based on the leave-one-out cross-validation method, the homotopy continuation method was used to optimize the LSSVM model parameters, and then the HC-LSSVM model was constructed with the goal of minimizing the sum of squares of the prediction error of the full sample retention one. Finally, the rationality and correctness of the model are verified by engineering application. The results show that the HC-LSSVM model constructed in this study can accurately predict the settlement of soft ground, which is superior to the common LSSVM model and solves the problem that the parameters of LSSVM model cannot be solved optimally. The research results provide a new method for prediction of soft soil settlement.

Prediction and Stability Assessment of Soft Foundation Settlement of the Fishbone-Shaped Dike Near the Estuary of the Yangtze River Using Machine Learning Methods

Fishbone-shaped dikes are always built on the soft soil submerged in the water, and the soft foundation settlement plays a key role in the stability of these dikes. In this paper, a novel and simple approach was proposed to predict the soft foundation settlement of fishbone dikes by using the extreme learning machine. The extreme learning machine is a single-hidden-layer feedforward network with high regression and classification prediction accuracy. The data-driven settlement prediction models were built based on a small training sample size with a fast learning speed. The simulation results showed that the proposed methods had good prediction performances by facilitating comparisons of the measured data and the predicted data. Furthermore, the final settlement of the dike was predicted by using the models, and the stability of the soft foundation of the fishbone-shaped dikes was assessed based on the simulation results of the proposed model. The findings in this paper suggested that the extreme learning machine method could be an effective tool for the soft foundation settlement prediction and assessment of the fishbone-shaped dikes.

The Effectiveness of Vacuum Consolidation to Soft Soil Settlement

The main issue of building constructions on soft soils is not a uniform settlement of soft ground, which has a slow process that effected construction failures and rising maintenance expenses. For many decades, to the improvement of ground soil stability, then applied using prefabricated vertical drain (PVD). Along the development of science and technologies, which followed by improvement of the soil stability method, that is called as Vacuum Consolidation Method (VCM). The objectives of this study are to determine how the effectiveness of vacuum consolidation with various patterns to soft soil settlement of constructions, and to find the right spacing of PVD installation due to un-uniform settlement of soft soils. The analysis of this study compared the numbers and rates of settlements in preloading, PVD, and VCM with various patterns, and to get a uniform settlement by two scenarios analysis, which are various spacing with single suction pressure (scenario 1) and single spacing with various suction pressures. Based on the result of analysis which showed the settlement of VCM in both patterns are 2.247 m in 105 days (square pattern) and 2.252 m in 90 days (triangular pattern). It means with a triangular pattern has 70.2 more effective than others in the rate of the settlement period. It also showed the VCM has larger than others in volume settlements. The results of 2 scenarios analysis showed that the implementation of scenario one was difficult due to various spacing, while scenario two can be implemented because numbers of settlements depend on suction pressure of the vacuum.

Effect Analysis of Different Treatment Methods for Soft Soil Foundation of Highway

With the rapid development of Guangdong, Hong Kong and Macao Bay area, the intercity rapid traffic network with high-grade highway as the main part has been developed rapidly. At the same time, the technology related to the soft soil foundation treatment of highway has also been developed. Based on a highway project in Foshan, Guangdong, this research used on-situ monitoring to study 4 kinds of soft soil foundation treatment methods, including preloading method, cement mixing pile, high-pressure jet grouting pile and Cement Flying-ash Gravel (CFG) pile, and then comparatively analyzed the influence of different treatment methods on the settlement of soft foundation.

Experimental and Numerical Studies on the Performances of Stone Column and Sand Compaction Pile–Reinforced Hong Kong Marine Clay

Abstract Stone columns (SCs) and sand compaction piles (SCPs) are widely utilized as effective methods to increase the bearing capacity and reduce the settlement of soft ground. In this study, a ph...

Development and Performance Analysis of Soil Flow Protector to Reduce Soft Soil Settlement Caused by Cavity Formation

Settlement of a relatively small magnitude occurs in box structures supported by pile foundations. However, if cavities are generated under the box structure, ground settlement can be accelerated by surrounding soil entering the cavities. In order for the structure to maintain stability for a long period of time, sustainable development to maintain the stability of the building must be continued. Preventing rapid ground settlement can lead to long-term structural stability and prevent the occurrence of life-threatening damage, thereby helping to maintain and build a sustainable urban infrastructure. Thus, in this study, a soil flow protector (SFP) that can be easily installed on the sides of the structure was developed to mitigate the aforementioned problem. Field tests and numerical analysis were performed to investigate the effect of SFP installation on structural stability and settlement reduction. After performing field experiments, it was found that SFP installation could reduce ground settlement and ground horizontal displacement. Moreover, for a 79.9-mm settlement, the safety factor was 1.315, which remained stable even when the settlement reached 345 mm. Hence, the developed SFP can be used to reduce soft ground settlement affecting box structures supported by pile foundations.

Prediction of soft soil foundation settlement in Guangxi granite area based on fuzzy neural network model

At present, the prediction of soft foundation settlement mostly use the exponential curve and hyperbola deferred approximation method, and the correlation between the results is poor. However, the application of neural network in this area has some limitations, and none of the models used in the existing cases adopted the TS fuzzy neural network of which calculation combines the characteristics of fuzzy system and neural network to realize the mutual compatibility methods. At the same time, the developed and optimized calculation program is convenient for engineering designers. Taking the prediction and analysis of soft foundation settlement of gully soft soil in granite area of Guangxi Guihe road as an example, the fuzzy neural network model is established and verified to explore the applicability. The TS fuzzy neural network is used to construct the prediction model of settlement and deformation, and the corresponding time response function is established to calculate and analyze the settlement of soft foundation. The results show that the prediction of short-term settlement of the model is accurate and the final settlement prediction result has certain engineering reference value.

A novel model for the cumulative plastic strain of soft marine clay under long-term low cyclic loads

Long-term cyclic loads with a stress level lower than the critical cyclic stress applied on soft soil can lead to soil deformation but not to failure. The Monismith model is known for its simplicity and capacity to describe the cumulative plastic strain of soil under cyclic loads. However, it is unsuccessfully applied in these cases because the plastic strain in this model would increase endlessly till to failure with increasing number of load cycles. To solve this problem, a novel empirical model with three parameters is proposed based on analogy analysis of the Hardin-Drnevich model and Monismith model. The proposed model is verified by experimental data from existing literature and is shown to have better capability and performance than the Monismith model in predicting the cumulative plastic strain of soft soil subjected to long-term low cyclic loads. The value of parameter b is recommended to be 0.5, and relationships of parameters a and c with the cyclic stress ratio are also proposed for soft clay. Applications of the proposed model are elaborated in detail, and in situ test results for settlement of soft subgrade are used to evaluate the performance of this model. The prediction results are consistent with the test results. The research results present a promising method for investigating the development of deformation and the settlement of soft foundation in the near-shore and off-shore areas caused by wave and/or traffic loads.

Effect of Groundwater Level Variation on Residual Settlement of Korean High-Speed Railway on Soft Ground

Groundwater drawdown is one of the factors that inducoe settlement in soft ground. However, the drawdown usually does not lead to a large settlement, and thus is not considered at the design stage. A few sites along the Honam High-Speed Railway experienced relatively large residual settlements, judging from residual settlement criterion of 30 mm in Korea. This settlement occurred during the dry season in Korea; accordingly, groundwater drawdown was pointed out as a cause of the settlement. This study focuses on the effect of groundwater level variation on residual settlement by field measurement and numerical analysis. The numerical simulation produced reasonably similar settlement behavior to that of the field measurements, which proves that the numerical analysis represents field performance. The comparison of numerical analysis between the constant and variable groundwater level clearly shows the effect of groundwater variation on the settlement of soft ground. The drawdown only leads to additional residual settlements of 7.3 and 8.3 mm at the surface of the natural ground and embankment. The total residual settlement is approximately 21.9 mm; thus, more than 33% of the settlement was caused by groundwater drawdown. Therefore, the groundwater variation should be considered at the design and construction stages to reduce residual settlement in the case of strict criterion.

Analysis of consolidation settlement of normally consolidated soil by layering under 3D conditions

This study analyzed the effects of conventional practice of calculating consolidation settlement of soft ground by dividing the ground into one or more layers. Based on a numerical analysis of the accuracy of the calculation and the settlement behavior resulting from layering, this study found that the existing settlement calculation method always underestimates settlement, and that the smaller the number of dividing layers, the smaller the calculated settlement is observed. In addition, when the ground is divided into an infinite number of layers, the settlement is 1.2 to 50 times larger than the case when the ground is considered as a single layer, and the difference grows larger at the lower ratio of an applied pressure to an effective stress (A0), the higher ratio of a layer thickness to a footing width (H/B), and the lower ratio of the length to width of a footing (L/B). The exact settlement can also be obtained under a single-layer condition, even when using the existing settlement calculation method, if the representative depth of calculation of the effective stress is set at a depth of approximately 10-38% from the top of the clay layer.

Numerical Analysis of Consolidation Settlement and Creep Deformation of Artificial Island Revetment Structure in a Large-Scale Marine Reclamation Land Project

Abstract In order to analyze the influential factors of soft foundation settlement in a marine reclamation land project, the consolidation settlement and pore pressure dissipation of the entire area are numerically simulated using Soft-Soil- Creep Model, in which the PLAXIS finite element software for professional geotechnical engineering is applied and empirical data of Japanese Kansai’s airport project are used. Moreover, the figures of settlement and pore pressure results in the different basic period are drawn, and the corresponding analysis conclusions are ob-tained based on the comparison among the results from the computational parameters of depth. In addition,, the influence rules of various parameters on settlement results is concluded through running the parameter sensitivity analysis in Soft-Soil-Creep Model, and the experience and conclusions can be for reference in the design and con-struction of similar large-scale marine reclamation land project. Also the empirical value method of the creep index has not been applied widely. Further research needs to be done.

Simplified method for predicating consolidation settlement of soft ground improved by floating soil-cement column

A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consolidation model and equal strain assumption, the governing equation was derived for the consolidation of clayey subsoil reinforced by soil-cement column. By modifying the boundary condition of the interface between the improved layer and underlying layer on seepage and pore-water pressure, the analytical solution of consolidation of soft ground improved by floating soil-cement column was developed under depth-dependent ramp load. The results of the parameter analysis of consolidation behavior show that the consolidation rate is closely related with the depth replacement ratio by the column and the permeability of upper layer. The influence of column-soil constrained modulus ratio and radius ratio of the influence zone to the column on consolidation is also affected by depth replacement ratio. The column-soil total stress ratio increases with time and approaches the final value accompanied with the dissipation of excess pore water pressure.