scholarly journals Deformation Response Research of the Existing Subway Tunnel Impacted by Adjacent Foundation Pit Excavation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xin Dong ◽  
Ling Mei ◽  
Shuyan Yang ◽  
Liang He
Keyword(s):  
Axial Strain ◽  
Retaining Wall ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Subway Tunnel ◽  
Three Dimensional Model ◽  
Foundation Pit ◽  
Maximum Displacement ◽  
Initial Stress State ◽  
Surrounding Soil

The excavation of foundation pits is one of the most important factors causing changes to the initial stress state of its surrounding soil, thus affecting the safety of nearby existing subway tunnels. In order to study the deformation in metro lines induced by adjacent foundation pit excavation, a three-dimensional model based on an actual engineering case was established, and the deformation regulations of the retaining wall, surrounding soil, and tunnels were investigated, which also validated the model’s feasibility. Additionally, the deformation and strain response of the subway tunnel under different selection parameters of the enclosing structure and soil were studied. The results showed that, after the foundation pit excavation, the soil inside the pit underwent an uplift, the surrounding soil outside of the pit showed vertical settlement, and the retaining wall created a deformation towards the interior of the pit. Mechanical parameters of plate elements have a small influence on the deformation of metro lines. Axial strain and maximum displacement of the subway tunnel increase with the increase in the soil’s Poisson’s ratio, and on the contrary, they decrease with the increase in the m-value and G 0 , ref . The maximum responses of the subway tunnel came from changes to G 0 , ref and υ . These analysis results can be used for the safety evaluation of subway tunnel operation, design, and construction in other similar engineering settings.

scholarly journals Safety Evaluation of Underground Caverns Based on Monte Carlo Method

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Qifeng Guo ◽  
Zhihong Dong ◽  
Meifeng Cai ◽  
Fenhua Ren ◽  
Jiliang Pan
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Cumulative Distribution ◽  
Three Dimensional Model ◽  
Maximum Displacement ◽  
The Monte Carlo Method ◽  
Underground Caverns ◽  
The Stability

In order to study the influence of joint fissures and rock parameters with random characteristics on the safety of underground caverns, several parameters affecting the stability of surrounding rock of underground caverns are selected. According to the Monte Carlo method, random numbers satisfying normal distribution characteristics are established. A three-dimensional model of underground caverns with random characteristics is established by discontinuous analysis software 3DEC and excavation simulations are carried out. The maximum displacement at the numerical monitoring points of arch and floor is the safety evaluation index of the cavern. The probability distribution and cumulative distribution function of the displacement at the top arch and floor are obtained, and the safety of a project is evaluated.

The Influence of Needle Eccentric Motion On Hole-to-Hole Injection Characteristics of a Two-Layered 8-Hole Diesel Injector

2021 ◽  
Author(s):  
Tianyu Jin ◽  
Yu Sun ◽  
Chuqiao Wang ◽  
Adams Moro ◽  
Xiwen Wu ◽  
...  
Keyword(s):  
Fuel Injection ◽  
Lateral Displacement ◽  
Three Dimensional ◽  
Injection Rate ◽  
Hole Injection ◽  
Three Dimensional Model ◽  
Maximum Displacement ◽  
Fuel Flow ◽  
Diesel Injection ◽  
Eccentric Motion

Abstract The stringent emission regulations diesel engines are required to meet has resulted in the usage of multi-hole and ultra-multi-hole injectors, nowadays. In this research study, a double layered 8-hole diesel injection nozzle was investigated both numerically and experimentally. A three-dimensional model of the nozzle which was validated with experimental results was used to analyze the injection characteristics of each hole. The validation was conducted by comparing experiment and simulation injection rate results, acquired simultaneously from all the holes of the injector and the model. The fuel flow rates of the lower layered holes are higher than those of the upper layered holes. Two different needle eccentricity models were established. The first model only included the lateral displacement of the needle during needle lift. The needle reached maximum displacement at full needle lift. The second model considered the needle inelastic deformation into consideration. The needle radially displaces and glides along with the needle seat surface during needle lift. When the eccentricity reached maximum in the radial direction, the needle began to lift upwards vertically. The differences in injection characteristics under the different eccentricity models were apparent. The results indicated that the cycle injection quantity, fuel injection rate and cavitation of each hole were affected during the initial lifting stages of the needle lift. As the eccentricity of the needle increases, the injection rate uniformity from the nozzle hole deteriorates. The result showed that the upper layered holes were affected by the needle eccentricity during needle lift.

Numerical Analysis of Composite Soil Nailing Wall

2014 ◽  
Vol 1065-1069 ◽  
pp. 48-52
Author(s):  
Shu Long Zhang ◽  
Fen Ting Lu
Keyword(s):  
Three Dimensional ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Soil Nailing ◽  
Construction Process ◽  
Three Dimensional Model ◽  
Foundation Pit ◽  
Finite Element Software ◽  
Ground Surface Settlement ◽  
Composite Soil Nailing

Abstract. The horizontal displacement of soil in slope and the change law of ground surface settlement are dynamically analyzed by building three dimensional-model of foundation pit with the finite element software, ABAQUS, to simulate the construction process of excavation and support, to figure out the influence of micro pile and waterproof curtain on composite soil nailing wall. The study indicates that mechanical model of soil nailing, waterproof curtain, micro pile, pre-stressed anchor interacting with soil can better simulate the construction process of composite soil nailing wall support and have higher calculation accuracy. The calculation can provide a reference for the design and construction of composite soil nailing wall.

Dynamic Analysis of Arch Dam Based on Observed Earthquake

2013 ◽  
Vol 438-439 ◽  
pp. 1542-1545
Author(s):  
Zheng Liu ◽  
Yong Gang Guo ◽  
Long Bang Qing
Keyword(s):  
Seismic Waves ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Arch Dam ◽  
Element Calculation ◽  
Dimensional Model ◽  
Acceleration Response ◽  
Three Dimensional Model ◽  
Water Interaction ◽  
Scientific Support

A three-dimensional model of dam-water-interaction system was built. Three different materials were used to model the dam, and the acceleration response of arch dam under the observed seismic waves was simulated. The results show that the dynamic reactions of the arch dam under observed earthquakes can well match the monitoring values, which means the established model of the arch dam is reliable. In the future, when great earthquakes happen, the stress strain situation of the key positions can be quickly obtained by the finite element calculation, which could provide scientific support for post-earthquake safety evaluation and decision-making.

Impact Assessment of Common Supported Excavation of Double Foundation Pits on the Adjacent Tunnel

2012 ◽  
Vol 170-173 ◽  
pp. 1524-1527 ◽  
Author(s):  
Hui Shen ◽  
Jin Feng Bi ◽  
Xian Qi Luo
Keyword(s):  
Simulation Analysis ◽  
Comprehensive Evaluation ◽  
Subway Tunnel ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Support Design ◽  
Maximum Displacement ◽  
Total Displacement ◽  
Common Support ◽  
Structure Lead

Based on the deep excavation engineering which used the common support design near the range of Suzhou Rail Transit Line 2, a 3-D numerical model was created to make the numerical simulation analysis of the deep foundation pit construction and obtain the comprehensive evaluation of the influence on the nearby subway tunnel stress and deformation when the 3 # and 4 # block foundation pits were excavated. The numerical results show that: when the pits are excavated to the basement, the total displacement value of the tunnel is 1.6mm. Because of the aspect ratio difference between the 3# and 4# block pits, the subway tunnel displacement of every direction trends to the 3# block. And the preserving soil area between the two blocks makes the tunnel stress present a symmetric distribution along the soil area's cross section. The surface settlements of soil behind enclosure structure lead to a great impact on the pipelines, whose maximum reaches 5mm. For comprehensive, the maximum displacement and spring back deformation of the subway tunnel meet the control requirements, with a certain margin of safety.

Deformation Monitoring for Subway Tunnels Based on TLS

2013 ◽  
Vol 864-867 ◽  
pp. 2744-2749 ◽  
Author(s):  
Gui Zhen He ◽  
Jun Yang
Keyword(s):  
Laser Scanning ◽  
Control Point ◽  
Three Dimensional ◽  
Deformation Monitoring ◽  
Subway Tunnel ◽  
Three Dimensional Model ◽  
Common Control ◽  
Adjacent Station ◽  
Subway Tunnels ◽  
Shanghai Metro

The paper studies Terrestrial Laser Scanning used in subway tunnel deformation monitoring. For special narrow subway tunnel structure, the accumulated error between the adjacent station can be eliminated by global registration pattern which is to set the common control point within the section ends. Point cloud slicing is used to calculate the radius of the circle by multi-point coordinate, deformation is fitted to curve to show the monitoring result by analyzing the center coordinates sequence trends and mean curvature. Three-dimensional model of subway tunnel not only improves the accuracy of deformation monitoring, but also reflects the overall deformation trend. This method is applied to monitor deformation for Shanghai Metro Line twelve, comparing with the total station method, high precision of deformation monitoring meet the need.

Rapid postearthquake safety evaluation of buildings using sparse acceleration measurements

2020 ◽  
pp. 147592172093629 ◽  
Author(s):  
Koji Tsuchimoto ◽  
Yasutaka Narazaki ◽  
Vedhus Hoskere ◽  
Billie F Spencer
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Nonlinear Model ◽  
Damage Index ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Training Data ◽  
Seismic Events ◽  
Analysis Model ◽  
Three Dimensional Model

After a seismic event, buildings need to be inspected to confirm their safety prior to reoccupation. As such, the rapid evaluation of the condition of individual buildings is important for minimizing disruption to lives and business. However, traditional manual inspection by experts is laborious and time-consuming. Structural health monitoring provides the potential to accelerate the required evaluation. This article proposes a cost-effective approach for rapid safety evaluation of buildings after seismic events using sparse acceleration measurements. First, a damage-sensitive feature is defined that can be used to infer the condition of buildings. Herein, the maximum interstory drift angle is proposed as a reliable damage index to classify the safety of buildings after seismic events. A convolutional neural network is then employed to uncover the complex relationship between the damage-sensitive features and the building condition. A five-story steel building is considered to validate the proposed approach. First, a three-dimensional nonlinear model of the building is created. To generate the required training data, a simplified nonlinear model is developed, along with a corresponding linear model, as use of the three-dimensional model is too computationally expensive. The training data for the convolutional neural network incorporates uncertainties in both the analysis model and the ground motion. Initial evaluation is conducted using the simplified nonlinear model, while final validation of the proposed approach is performed using the results of the three-dimensional nonlinear analysis model subjected to historical earthquakes. The results demonstrate the ability of the proposed approach to accommodate differences between the in-situ structure and the analysis model, as well as the efficacy of this approach for rapid postearthquake safety evaluation of buildings.

Analysis of Soil’s Horizontal Displacement behind Retaining Wall Caused by Foundation Pit Excavation

2012 ◽  
Vol 170-173 ◽  
pp. 8-12
Author(s):  
Tao Jiao ◽  
Wei Chen ◽  
Jian Ping Zhou
Keyword(s):  
Boundary Condition ◽  
Retaining Wall ◽  
Three Dimensional ◽  
Horizontal Displacement ◽  
Displacement Boundary Condition ◽  
Working Process ◽  
Foundation Pit ◽  
Displacement Boundary ◽  
Research Material ◽  
Range Of Influence

Currently the study of soil’s horizontal displacement caused by foundation pit excavation is still deficient. Based on existing research material, this paper builds the displacement models of soil’s horizontal displacement. Through adopting three-dimensional finite difference method, working process and related influencing factors are simplified into displacement boundary condition which is applied to numerical model to analyze soil’s horizontal displacement. The conclusion can be used to estimate displacement of soil behind retaining wall, such as soil’s horizontal displacement and range of influence.

Impact Analysis of Foundation Pit Excavation on the Deformation of Nearby Subway Tunnel

2014 ◽  
Vol 935 ◽  
pp. 233-236
Author(s):  
Hui Shen ◽  
Jin Feng Bi ◽  
Tong Qi Ping
Keyword(s):  
Impact Analysis ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Subway Tunnel ◽  
Foundation Pit ◽  
Soil Subsidence ◽  
Maximum Value ◽  
Margin Of Safety ◽  
Design Proposal ◽  
The Impact

Bracing of foundation pit design proposal based on the excavation near a block of Suzhou Rail Transit Line 1 is used to build a subway tunnel-pit-envelope three-dimensional computational model, which is analyzed by FLAC3D, software for numerical simulation analysis, to evaluate the impact of the foundation pit excavation on the deformation of the subway tunnel. The calculated results show that: when the pit is excavated to the bottom, the deformation of the tunnel achieves the maximum value, 0.6mm of y direction and 6.54mm of z direction. The pipelines with shallow depth are subject to the deformation caused by the soil subsidence back of the envelope, whose maximum value has reached 7.6mm beyond the control standards. In terms of the deformation of the subway tunnel structure, the deformation can meet the control requirements, and have a certain margin of safety.

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