Analysis Of Ground Settlement Research Articles

Three-Dimensional Modeling and Analysis of Ground Settlement Due to Twin Tunneling Using GIS

Ground settlement occurs because of the surrounding ground behavior during tunnel excavation. A high chance of its occurrence could cause the collapse of buildings; therefore, the accurate prediction and assessment of ground settlement are necessary when structures are concentrated in urban regions. This study leverages Geographic Information Systems (GIS) and 3D modeling to evaluate the effects of tunnel excavation on the ground settlement and damage of buildings along the Mandeok–Centum underground highway in Busan. It integrates the field topography with building data to simulate and visualize construction-induced interactions. Numerical analysis is used to assess the effects of the terrain elevation, building presence, excavation sequences, and lag distance between the twin tunnels on the settlement. The results indicate that high terrain elevation, dense building layouts, and shorter distances between tunnels increase settlement. Furthermore, this study deduces that bidirectional excavation causes a rapid increase in settlement compared with parallel excavation, which is evident from the variations in the inflection points during the excavation process. Finally, this study estimates the damage to buildings and ground settlements and visualizes risk maps using GIS, emphasizing the practicality of 3D modeling based on GIS.

New Approach to Ground Settlement Analysis During Box Jacking in Spatially Variable Soils

New Approach to Ground Settlement Analysis During Box Jacking in Spatially Variable Soils

Probabilistic analysis of ground settlement induced by tunnel excavation in multilayered soil considering spatial variability

Accurately evaluating and predicting the ground settlement during tunnel excavation are crucial for ensuring the stability of tunnel structures. However, the traditional methods always use representative (or average) values for deterministic analysis and rarely consider the spatial variability of soil properties. In this study, a probabilistic analysis of ground settlement under uncertain soil properties was performed based on random fields combined with the finite-difference method. The random fields of Young’s modulus and friction angle of multilayered soils were generated based on the Cholesky decomposition in a manner consistent with a specified numerical mesh. The effects of spatial variability and cross-correlation in random fields on the ground settlement were investigated in detail. The results demonstrate that spatially variable soils significantly influence the probability of failure, magnitude, and longitudinal profile of ground settlement in the vertical direction. It can be found that the allowable ground settlement of the limit state function also dominated the degree of the vertical scale of fluctuation on stability. Neglecting the cross-correlation between the two random fields results in an overestimation of the probability of failure compared with an independent analysis. Subsequently, the failure mechanisms of ground settlement in spatially random soils were discussed.

Numerical analysis of uneven settlement of highway subgrade based on nonlinear algorithm

Abstract In order to accurately and easily calculate the settlement of the foundation, a high-speed roadbed based on a nonlinear algorithm is proposed to broaden the uneven and uniform reduction numerical analysis. The basic loading test results of the foundation loading test results in a series of sand-bearing test results made by gear suppressive elastic Mohr–COMB were verified using general finite element procedure ABAQUS. The results show that for most original slopes of 1:1.5 highways, according to the above research results and relevant specifications, the high-wig ratio of the steps should be controlled in 1:1.2 to 1:1.5. That is, when the width is controlled in a range of about 1.2 m, the height of the step is held at 0.8–1.0 m. The larger the role of filling the top surface, the more obvious is the role of the geogrid to reduce the settlement of the road embankment. Under the conditions of the same subgraduation, the reinforced road embankment of the geotechnical grille, the settling effect that occurs in the load activity is also more obvious. This method offers a better design and construction technique for expanding the project, investigates the control of differential settlements caused by excavation step size and geogrid size, and seeks more complete, scientific programmes. It has the potential to drastically reduce the project’s investigation effort, shorten the survey cycle, and provide incalculable economic and social benefits. Therefore, the research results of this paper have improved the reliability of existing ground settlement analysis.

Analysis of Ground Settlement during Shield Tunnel Construction in Soft Soil

Analysis of Ground Settlement during Shield Tunnel Construction in Soft Soil

Disturbance Process of Sandy Gravel Stratum Caused by Shield Tunneling and Ground Settlement Analysis

This paper analyzed the earth pressure, pore pressure, and surface settlement of the Luoyang urban rail transit tunnel in a sandy gravel stratum (Henan Province, China) under different burial depths by using field measurement methods. The results showed that the earth pressure as well as pore pressure of the soil layer above the working surface increased sharply and reached their maximum values when the cutter head of the shield gradually crossed the working surface. During the completion of synchronous grouting, the earth pressure and pore pressure increased slightly; when shield tunneling passed through the working surface, the earth pressure is smaller than the original earth pressure due to the unloading effect. The surface settlement curve above the tunnel took on a “V” shape after the completion of the left-side tunnel excavation, conforming to the normal distribution pattern. The surface settlement curve above the two tunnels took on a “W” shape after the completion of the right-side tunnel excavation, which is in good agreement with the proposed theoretical calculations. The findings of this study can help for better understanding the control of safety risk during shield construction.

Comparison study of Excavation Stability using Different Tunnel Excavation Methods

For the safety and efficiency of tunnel construction, optimal schemes for tunnel excavation with different surrounding rock grades should be proposed to provide references for engineering construction. Through 3D numerical simulation, the mechanical properties of the surrounding rock during tunnel construction were studied by 3D numerical simulation. For different surrounding rock grades, three different excavation methods were simulated. A comparative analysis of ground settlement, surrounding rock displacement, and maximum principal stress caused by different construction methods was also performed. The results show that different construction methods have a small impact on the displacement of surrounding rock. When the surrounding rock is of grade I, the maximum vertical displacement of the excavation surface is less than 2 mm. Bench cut method can be used for excavation with fast construction speed. When the surrounding rock is of grade IV, the stratum settlement and excavation surface displacement are large. The Center diagram method can ensure the construction progress and minimize the vertical displacement of surrounding rock. When the surrounding rock is of grade V, the displacement caused by tunnel excavation further increases. The double-side drift method can be adopted to minimize the stratum settlement and surrounding rock displacement.

Analysis of Ground Settlement Caused by Double-line TBM Tunnelling Under Existing Building

TBM tunnelling is less used in the subway construction in prosperous city due to the limitation of the engineering geological conditions. The studies on the influence of the TBM construction on the existing buildings are also limited. Therefore, based on the engineering case of tunnel crossing existing building in the section of Haiboqiao ~ Xiaocunzhuang station of Qingdao Metro Line 1, the numerical model that simulates the construction process of TBM tunnelling in slightly weathered granite layer is established by three-dimensional finite difference software FLAC3D to analyze the influence of TBM tunnelling. The comparisons between ground deformations obtained by FLAC3D and field monitoring data in different construction stages of double-line tunnel have been made firstly to validate the numerical model. Then the ground settlement characteristics, differential settlement and the stress distribution of the existing building and the stress of segment structure have been analyzed. During TBM tunnelling under existing building, the settlement of the building as a whole tends to increase, with the maximum measured settlement of 5.45 mm and the maximum differential settlement of 1.58 mm, which meets the control standard of relevant codes. Ground settlement groove along the transverse and vertical sections occurs near the building and tunnels, and the settlement becomes smaller with the farther the distance from the building and tunnels. The settlement curve on the cross section changes dynamically and is approximately V-shaped, and its width is about 5 ~ 6 times diameter of the tunnel. For the same cross section, the range of the settlement groove after tunnelling right line increases obviously compared with that after tunnelling left line (first construction), the settlement values also increase, and the symmetrical axis of the settlement curve is shifted to the right. For the segment structure, the maximum principal tensile stress occurs inside the arch bottom of the tunnel, while the maximum principal compressive stress occurs near the arch top and arch waist, with obvious stress concentration. For the existing building, the maximum principle tensile stress occurs at the door opening of the wall on the first floor and the maximum principal compressive stress is at the corner of wall. They are less than the tensile strength and compressive strength of the segment structure and building respectively, and have enough safety margins. This paper can provide important practical reference for the deformation control and protection design of surrounding buildings for relative construction.

Ground Settlement analysis of Metro Interval using PBA method in the Loess region

In the construction of urban subway, the control of surface settlement has become the key and difficult point in the construction. As a common method in subway tunnel construction, PBA method has been widely used in many areas in China. This method performs well in settlement control. In addition, the supporting system of piles, beams, and arches formed during the construction process of this method effectively avoids the impact of the open-cut method on urban traffic. Therefore, this paper will combine the engineering conditions and the existing research results to simulate the various construction stages of the subway interval excavation in the loess area by establishing a Midas model. Combined with the results of numerical simulation, four increasing stages of surface settlement and corresponding settlement ratios are obtained, and the characteristics of surface settlement troughs are analyzed. This research is helpful to further understand the increasing law of ground settlement during the construction of metro interval in loess area.

A Novel Method for Analyzing the Factors Influencing Ground Settlement during Shield Tunnel Construction in Upper-Soft and Lower-Hard Fissured Rock Strata considering the Coupled Hydromechanical Properties

Focusing on the special stratum conditions of upper-soft and lower-hard fissured rock strata, this paper conducts quantitative research and analysis on the factors influencing the ground settlement caused by shield tunnel construction considering the coupled hydromechanical properties and presents a corresponding numerical simulation-artificial neural network-Bayesian network- (NS-ANN-BN-) based method. In this method, with a subway shield tunnel as the engineering context, three numerical models are established, in which the shield tunnel is located in soft strata, the shield tunnel is located in semisoft and semihard strata, or the shield tunnel is located in hard strata. According to the numerical simulation (NS) calculations, the ground settlement values under the three types of strata are 38.96 mm, 10.42 mm, and 3.13 mm, respectively. A radial basis function artificial neural network (RBF-ANN) is used to establish the nonlinear mapping relationship between the stratum parameters and the ground settlement, and the training samples and test samples are generated through NS to train the RBF-ANN. After the training is completed, the accuracy of the neural network meets the requirements. The elastic moduli of coarse sand~gravel sand k3 and moderately weathered rhyolite k4 and the cohesion of moderately weathered rhyolite c4 are selected as the key parameters. A large number of training cases are generated through the RBF-ANN, and the Bayesian network (BN) prior probability is calculated by self-learning. A BN model of ground settlement for shield tunnel construction in the upper-soft and lower-hard fissured rock strata is established. The BN back analysis method is used to quantitatively analyze the influencing factors of the ground settlement. The results show that when the tunnel is located in soft strata, the surface settlement is mainly affected by parameter k3. When the ground settlement increases considerably, the three parameters all have a strong influence. When the tunnel is located in semisoft and semihard strata, the influence of the three parameters on the ground settlement is weak. When the tunnel is located in hard strata, the ground settlement is mainly affected by parameter k4. When the ground settlement greatly increases, parameters k3 and c4 have less influence. When the tunnel is located in strata with different soft-hard ratios, the ground settlement is mainly affected by the elastic moduli of coarse sand~gravel sand and moderately weathered rhyolite. This method can provide a reference for the ground settlement analysis of shield tunnel construction in areas with similar fissured rock strata.

Analysis of Ground Settlement in Metro Tunnel Construction with Shield Tunneling Method

With the continuous development of underground space, subway tunnel construction methods are constantly updated and developed. And shield tunnel method has become one the most common methods of subway tunnel construction. However, shield construction is often accompanied with the occurrence of surface subsidence. There may be a collapse of the surface when the surface settlement reaches a certain amount and the up buildings on the surface may be seriously influenced. The construction model was established based on FLAC3D software by using the engineering geological characteristic parameters of the study area and the observation data of ground subsidence during construction, which was compared and verified with the field vmonitoring value, and the subsidence was simulated and predicted. Using FLAC3D to establish a settlement prediction model for tunnel excavation and record the space-time changes of surface subsidence, it can better reflect the land subsidence situation and law in the horizontal and vertical directions of the axis of the subway tunnel.

Three dimensional finite element analyses of ground settlement and structural damage caused by irrigation of desert landscapes overlying collapsible soil strata

ABSTRACT Experience in the United Arab Emirates (UAE) has revealed the settlement risk to foundations built on collapsible strata when such strata become increasingly wet due to irrigation of lawns. This paper presents a numerical analysis of ground settlement at a location in the UAE where structural damage occurred, prompting a forensic investigation that involved borehole drilling and measurement of subsidence and structural failure characteristics. MidasTM 3D finite element programme is used with field information from boreholes and irrigation specifications to simulate and predict the settlement profile for a typical pair of residential villas surveyed. Important factors are taken into account including the depths and thicknesses of the collapsible strata, the in-situ stresses, transient water flow, irrigation cycles, water table depth and the soil-structure mechanical properties. The maximum settlement of the boundary wall is predicted to be 157 mm, which agrees closely with the measured value of 165 mm. In addition, the predicted surface displacements are consistent with the observed ground and boundary wall deformation patterns.

Sensitivity analysis of ground settlement induced by pipe-jacking construction in soft soil stratum

Taking the ground settlement while pipe-jacking construction in soft soil as the engineering background, the effect of pipe jacking were studied by numerical simulation. It focused on the factors that mainly influenced surface settlement of ground including in-situ stress release rate (or ground loss ratio), chamber pressure, elastic modulus of soil, buried depth and diameter of pipe. That would provide theoretical basis for taking measures to reduce surface subsidence while jacking. The main conclusions were as follows: (1) The in-situ stress release rate and pipe diameter were proportional to the surface subsidence. (2) Chamber pressure, elastic modulus and buried depth were inverse proportional to the surface subsidence. (3) From the point of view of the influence on surface settlement, the sensitivity of pipe diameter and elastic modulus of soil was the greatest, followed by burial depth and chamber pressure, and the stress release rate was the smallest.

Modeling and Analysis of Ground Settlement Between a Flyover and Reinforced Soil Embankment

AbstractDevelopment of the transport infrastructure in Poland has contributed to the implementation of various technologies of construction of bridges and their components. Use of reinforced soil for construction of embankments, retaining structures (RSS walls) and abutments is one of the solutions which has been frequently used for the past twenty years. Shortly after its development, the technology proposed by Henri Vidal in 1966 also gained appreciation in Poland [4]. Reinforced soil bridge abutments started to be widely used in Poland at the turn of the 20th century. The bridge facilities at the junction of Trasa Siekierkowska route and Wał Miedzeszyński Street in Warsaw, which were built in the years 2000÷2002, are an example of structures from that period. The authors of this paper have been particularly interested in the outermost supports of the reinforced concrete flyovers which were constructed in the form of intermediate reinforced soil abutments. Offsets – the vertical displacements, in the range of 15÷25mm, emerging between the level of the road surface and the steel elements of the expansion joints which separate the flyover’s structure from the embankment – were observed in 2015, in the course of regular inspections. While accounting for the observations which have been made, the surveying measurements and the ground investigation, the paper diagnoses and describes the mechanism which led to the emergence of the offsets. Potential patterns of the occurrence of additional settlements, as the reason for emergence of the offsets, were identified and analyzed. The settlement of the outermost support (abutment), as a result of increase of relative density of alluvial sands due to the dynamic interaction of the roadways of Wał Miedzeszyński Street, was analyzed. Analytical and numeric approaches were used in the course of analysis while relying on PLAXIS and MIDAS software.

Analysis of ground settlement induced by Earth pressure balance shield tunneling in sandy soils with different water contents

In this paper, reduced-scale tests and numerical simulations were used to investigate the response of sandy soils with different water contents when Earth pressure balance shield (EPBS) tunneling was conducted. Both surface and subsurface settlement of the ground were analyzed, and the settlement data were fitted with different equations from previous studies. The results showed that the water content in a sandy soil has a significant effect on both the profile and magnitude of the settlement of the surface and subsurface. When the water content was less than a certain value, the increment of water content obviously contributed to decrements in the magnitude of ground settlement, and there was an obvious increment in the coefficient of the width of the settlement trough width and a simultaneous greater degree of nonlinearity for the ground settlement parameter (K) in the subsurface. When the water content was greater than this certain value, the increment of water content produced the opposite results. Both the modified Gaussian curve and the yield density curve provide better fits of the data for the settlement of the surface of dry, sandy soil than the Peck curve. When the water content was less than this certain value, the three curves for the subsurface settlement data were almost the same. When the water content was greater than this certain value, the modified Gaussian curve and the yield density curve provided better fits of the surface settlement data than the Peck curve.

Monitoring and Analysis of Ground Settlement Induced by Tunnelling with Slurry Pressure‐Balanced Tunnel Boring Machine

A case study of monitoring and analysis of ground settlement caused by tunnelling of stacked twin tunnels for underground metro line construction through the densely populated area using the slurry pressure‐balanced TBM is presented. Detailed ground settlement monitoring was carried out for the initial stage of down‐track tunnelling in order to estimate trough width factor and volume losses including face, shield, and tail losses. In addition, using the gap model, prediction of volume loss and ground settlement was carried out with consideration of the ground condition, TBM configurations, and actual operation data. The predictions of the gap model were compared with the observed results, and adjustment factors were determined for volume loss estimation. The adjusted factors were applied to predict ground settlement of the up‐track tunnel, and its results were compared with the field measurements.

Proportion Analysis of Ground Settlement Caused by Excavation and Dewatering of A Deep Excavation in Sand Area

Ground settlement caused by combined influence of excavation and dewatering in sand area is discussed in this paper. The soil seepage-stress interaction model in a deep excavation is established based on the modified Mohr–Coulomb model using finite element theory, in order to analyze seepage field and ground settlement surrounding the deep excavation caused by well dewatering and soil excavation. Ground settlement caused by excavation and dewatering individually are obtained from the numerical investigation. A case history in northeastern China is adopted in this study, and the results show that, impact of ground settlement caused by excavation and dewatering is about three times the excavation depth (H). The maximum settlement point of monitoring sections appears at a distance of 22 m from the deep excavation, about 0.82–0.96 H. The ground settlement caused by soil excavation is dominant from 10 to 20 m away from the deep excavation, while the ground settlement beyond 25 m from the excavation is mainly caused by dewatering. Settlement caused by dewatering is kind of irreversible settlement, so the ground settlement of a deep excavation caused by well dewatering can not be ignored during design and construction of excavation engineering.

RETRACTED: Ground Settlement in Urban Structures Exposed to Geo-Environmental and Anthropic Hazards: A Case Study for Galati City

A case study including a detailed ground settlement analysis is made for a particular loess structure located in the city of Galati, Romania, in order to assess the interdependence of geo-environmental and anthropic settlement triggering factors in the urban system context. In the first part of the study, loess behavior and its effects on built environment are analyzed and discussed based on worldwide historic expertise and current issues. An integrative analysis of loess deposits in natural state, with reference to induced-hydraulic and stress conditions, which was performed by laboratory and in-situ investigations, is then reported. An assessment of basic geotechnical parameters, as well as small-scale modeling of loess settlements at wetting under self-weight were conducted in order to select the most representative experimental area, from the point of view of specific soil structure behavior. Field monitoring surveys were performed to obtain information for quantitative evaluation of settlement time-dependent evolution, by the simulation of excessive moisture. The processing and analysis of experimental data gathered for natural and improved ground conditions revealed that the settlement amplitude of loess deposits with high sensitivity to wetting under self-load can be significantly reduced by the selection of adequate consolidation solutions, based on realistic and undisturbed environmental conditions. The study of soil structure behavior under simultaneous settlement-triggering factors can be integrated in multi-hazard analysis as a support for efficient strategies and mitigation measures, with applicability in the urbanization process, building and foundation design and environmental protection.

Ground Settlement in Urban Structures Exposed to Geo-environmental and Anthropic Hazards: A Case Study for Galati

A case study including a detailed ground settlement analysis is made for a particular loess structure located in the city of Galati, Romania, in order to assess the interdependence of geo-environmental and anthropic settlement triggering factors in the urban system context. In the first part of the study, loess behavior and its effects on built environment are analyzed and discussed based on worldwide historic expertise and current issues. An integrative analysis of loess deposits in natural state, with reference to induced-hydraulic and stress conditions, which was performed by laboratory and in-situ investigations, is then reported. An assessment of basic geotechnical parameters, as well as small-scale modeling of loess settlements at wetting under self-weight were conducted in order to select the most representative experimental area, from the point of view of specific soil structure behavior. Field monitoring surveys were performed to obtain information for quantitative evaluation of settlement time-dependent evolution, by the simulation of excessive moisture. The processing and analysis of experimental data gathered for natural and improved ground conditions revealed that the settlement amplitude of loess deposits with high sensitivity to wetting under self-load can be significantly reduced by the selection of adequate consolidation solutions, based on realistic and undisturbed environmental conditions. The study of soil structure behavior under simultaneous settlement-triggering factors can be integrated in multi-hazard analysis as a support for efficient strategies and mitigation measures, with applicability in the urbanization process, building and foundation design and environmental protection.

Modeling of shield-ground interaction using an adaptive relevance vector machine

Shield tunneling method is widely adopted in tunneling projects. Analysis of ground settlement is required as an effective way for minimizing the potential damage caused by tunneling. Many efforts have been devoted for this purpose using various methods such as empirical approaches and numerical modeling. However, there are multiple factors that may influence the ground settlement, and the shield-ground relationship is highly non-linear and complex. To understand the complex soil behavior in response to shield penetration, a model that can establish the relationship and make accurate predictions for tunneling-induced ground settlement is needed. This paper proposed a model based on relevance vector machines (RVMs) to develop the predictive relations. Adaptive feature scaling factors were introduced as an inherent mechanism that enables RVMs to identify the relative importance of each input factor, and an optimization method for obtaining the appropriate values of feature scaling factors is proposed. The potential of the proposed adaptive model was investigated by applying it to tunnels that bored by an earth pressure balance (EPB) shield machine. Three categories of factors, namely tunnel geometry, geological conditions and shield operational parameters were considered in the model. The results demonstrate that the proposed model has competitive predictive capacities and that the adoption of adaptive feature scaling factors can enhance the prediction accuracy and provide a measure of the relative importance of each input factor. Moreover, the implementation of the adaptive RVM model is relatively simple. There is no need to set model parameters because they can be automatically optimized during model training, which makes the method a practical tool for geotechnical engineers to evaluate ground reactions during tunnel excavation.