scholarly journals Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Haoshuang Niu ◽  
Xiaolin Weng ◽  
Chao Tian ◽  
Deng Wang
Keyword(s):  
Model Test ◽  
Load Distribution ◽  
Soft Clay ◽  
Back Analysis ◽  
Horizontal Load ◽  
Vertical Load ◽  
Linear Distribution ◽  
Parabolic Distribution ◽  
Mode 2 ◽  
Distribution Mode

Combined with the soft clay layer of Foshan metro, a back-analysis method combining model test and numerical simulation is developed. First, the similitude criterion for the model used in this study was derived from similarity theory and elasticity mechanics equations. Artificial clay is prepared by mixing kaolin, bentonite, loess, and river sand in proportions of 4 : 2: 3 : 1. Gypsum, water, and borax are mixed in proportions of 1 : 0.7 : 0.015 to simulate the tunnel lining. The model tests were carried out based on four load modes: the combination of mode 1, vertical load distribution and horizontal load linear distribution, mode 2, vertical load distribution and horizontal load parabolic distribution, mode 3, vertical load parabolic distribution and horizontal load linear distribution, and mode 4, vertical and horizontal load parabolic distribution. Then, the calculation model corresponding to the four load modes is established using ABAQUS, and the measured data is back-analyzed as the known quantity. The specific load values obtained were 359 kPa, 380 kPa, 361 kPa, and 368 kPa by the load-internal force curve. The bending moment and axial force are calculated by substituting the back-analysis load values back into the model and comparing the results with the measured values; it was found that the internal forces under the back-calculation load still deviated by varying degrees. By using the comprehensive error function E to evaluate the advantages and disadvantages of the four distribution modes, the comprehensive errors are 4.3%, 1.7%, 6.5%, and 5.9%, respectively. That is, the error of load distribution of mode 2 (the combination of vertical load distribution and horizontal load parabolic distribution) is the lowest and is highly consistent with the measured value, which is the closest to the characteristics of the load pattern of the stratum.

Study on the Bearing Mechanism of Bucket Foundation for Offshore-Wind Turbine in Soft Clay

2011 ◽  
Vol 71-78 ◽  
pp. 1795-1804
Author(s):  
Jian Feng Wang ◽  
Hai Tao Dai ◽  
Ming Qin
Keyword(s):  
Large Scale ◽  
Soft Clay ◽  
Bending Moment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Horizontal Load ◽  
Vertical Load ◽  
Bucket Foundation ◽  
Finite Element Software ◽  
Moment Load

Based on numerical platform of large-scale finite element software, this paper investigates the function mechanisms of vertical load, horizontal load, and bending moment load of soft-clay-base bucket foundation. Then the corresponding load bearing characteristics of each load type of soft-clay-base bucket foundation are determined.

Model Test and Finite Element Analysis of Squeezed and Branch Pile Bared Vertical and Horizontal Loads

2013 ◽  
Vol 470 ◽  
pp. 1101-1104
Author(s):  
Yue Hui Li ◽  
Xiao Juan Gao ◽  
Guo Hua Zhong
Keyword(s):  
Bearing Capacity ◽  
Model Test ◽  
Horizontal Displacement ◽  
Horizontal Load ◽  
Vertical Load ◽  
Load Bearing Capacity ◽  
Element Analysis ◽  
Load Bearing ◽  
Practical Engineering ◽  
Vertical Bearing

Model tests of the squeezed and branch pile with or without vertical load are carried out and the horizontal load bearing capacity are studied in this paper. Based on the model test results, the influence of vertical load to squeezed and branch pile horizontal load bearing capacity and the influence of horizontal load to squeezed and branch pile vertical bearing capacity are analyzed with FEM. The analysis results show that the vertical load may increase the lateral bearing capacity of pile, and the horizontal load may decrease the vertical settlement, but horizontal load may increase the horizontal displacement and moment of the pile body and lead to instability and cracking failure. This should be pay more attention in the practical engineering.

Model Test Study on the Effect of Vertical Lode on Horizontal Bearing Capacity of Disk Pile

2012 ◽  
Vol 446-449 ◽  
pp. 1804-1807
Author(s):  
Fan Li Meng ◽  
Guang Yu Sun ◽  
Cheng Yuan Lu
Keyword(s):  
Bearing Capacity ◽  
Model Test ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Combined Loading ◽  
Horizontal Load ◽  
Vertical Deformation ◽  
Vertical Load ◽  
Disk Diameter ◽  
Test Study

In order to study how it influence the horizontal bearing capacity of the disk pile when there exists a vertical load, a group of model tests has been designed. Three double-disk piles were used in the test, and the distance of the two disks is 5 times as the disk diameter. First drew a vertical load V=200N/300N/400N on the top of pile1/2/3 respectively, then put on the horizontal load stage by stage. And by the test, we can study the differences of the pile bearing properties such as changes in the pile bending moment, the horizontal and vertical deformation on the top. Experiment showed that when the vertical load is quite small（V=200N、300N）, the existence of vertical load has little to do with horizontal bearing capacity. When a vertical load increases to a certain value（V=400N）, The maximum bending moment and horizontal displacement of the pile under the same horizontal load reduce, which indicates that the disks of the pile play a significant role in bearing combined loading.

scholarly journals Behavior Characteristics of Single Batter Pile under Vertical Load

2021 ◽  
Vol 11 (10) ◽  
pp. 4432
Author(s):  
Jiseong Kim ◽  
Seong-Kyu Yun ◽  
Minsu Kang ◽  
Gichun Kang
Keyword(s):  
Bearing Capacity ◽  
Relative Density ◽  
Model Test ◽  
Ground Surface ◽  
Bending Moment ◽  
Vertical Position ◽  
Vertical Load ◽  
Behavior Characteristics

The purpose of this study is to grasp the behavior characteristics of a single batter pile under vertical load by performing a model test. The changes in the resistance of the pile, the bending moment, etc. by the slope of the pile and the relative density of the ground were analyzed. According to the results of the test, when the relative density of the ground was medium and high, the bearing capacity kept increasing when the angle of the pile moved from a vertical position to 20°, and then decreased gradually after 20°. The bending moment of the pile increased as the relative density of the ground and the batter angle of the pile increased. The position of the maximum bending moment came closer to the ground surface as the batter angle of the pile further increased, and it occurred at a point of 5.2~6.7 times the diameter of the pile from the ground surface.

Numerical Simulations of Dynamic Embedment During Pipe Laying on Soft Clay

2009 ◽  
Author(s):  
D. Wang ◽  
D. J. White ◽  
M. F. Randolph
Keyword(s):  
Soft Clay ◽  
Simple Approach ◽  
Published Data ◽  
Vertical Load ◽  
Centrifuge Model ◽  
Upper Limit ◽  
Different Types ◽  
Element Approach ◽  
Pipeline Design ◽  
Centrifuge Model Tests

Prediction of the as-laid embedment of a pipeline, which affects many aspects of pipeline design, is complicated by the dynamic motions that occur during the lay process. These motions cause pipelines to embed deeper than predicted based on static penetration models, as the seabed soils are both softened and physically displaced by the pipeline motion. This paper describes the results of 2D numerical analyses using a large displacement finite element approach aimed at quantifying pipeline embedment due to cyclic lateral motion at various fixed vertical load levels. The validity of the numerical results is first assessed by comparison with published data from centrifuge model tests in two different types of clay. A parametric study varying the normalized vertical load is then presented, which suggests a simple approach for estimating an upper limit to the dynamic embedment.

scholarly journals Experimental Analyses of the Major Parameters Affecting the Intensity of Outbursts of Coal and Gas

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
W. Nie ◽  
S. J. Peng ◽  
J. Xu ◽  
L. R. Liu ◽  
G. Wang ◽  
...  
Keyword(s):  
Water Content ◽  
Relative Intensity ◽  
Gas Content ◽  
Horizontal Load ◽  
Vertical Load ◽  
Range Analysis ◽  
Factors Affecting ◽  
Mining Depth ◽  
Physical Experiments ◽  
Relative Threshold

With an increase in mining depth and production, the intensity and frequency of outburst of coal and gas have a tendency to increase. Estimating the intensity of outbursts of coal and gas plays an important role because of its relation with the risk value. In this paper, we described the semiquantitative relations between major parameters and intensity of outburst based on physical experiments. The results showed increment of geostress simulated by horizontal load (from 1.4, 2.4, 3.2, to 3.4 MPa) or vertical load (from 2, 3, 3.6, to 4 MPa) improved the relative intensity rate (3.763–7.403% and 1.273–7.99%); the increment of porosity (from 1.57, 2.51, 3, to 3.6%) improved the relative intensity rate from 3.8 to 13.8%; the increment of gas pressure (from 0, 0.5, 0.65, 0.72, 1, to 1.5 Mpa) induced the relative intensity rate to decrease from 38.22 to 0%; the increment of water content (from 0, 2, 4, to 8%) caused the relative intensity rate to drop from 5.425 to 0.5%. Furthermore, sensitivity and range analysis evaluates coupled factors affecting the relative intensity. In addition, the distinction with initiation of outburst of coal and gas affected by these parameters is discussed by the relative threshold of gas content rate.

Analysis and Process Control of the Deformation for Deep Excavation in Soft Clay

2014 ◽  
Vol 580-583 ◽  
pp. 395-400
Author(s):  
Hui Liu ◽  
Wei Bin Li ◽  
Hong Tao Liu
Keyword(s):  
Process Control ◽  
Soft Clay ◽  
Back Analysis ◽  
Control Model ◽  
Prediction System ◽  
Deep Excavation ◽  
Dynamic Prediction

Mechanisms of the distortion of deep excavation in soft clay are recommended on the beginning. Plane FEA method is combined with back-analysis from displacement on this paper to establish a dynamic prediction system of the distortion of deep excavation, which is proved to be viable by practice. Combining with the idea of process control, a process control model of the distortion of deep excavation is established on this paper. It is divided into three parts: advance control, observation and dynamic prediction, process control in the construction.

Soil-Structure Interaction of Heated Pipeline Buried in Soft Clay

2002 ◽  
Author(s):  
Alvaro Maia da Costa ◽  
Carlos de Oliveira Cardoso ◽  
Claudio dos Santos Amaral ◽  
Alejandro Andueza
Keyword(s):  
Challenging Behavior ◽  
Soft Clay ◽  
Back Analysis ◽  
Interaction Model ◽  
Material Behavior ◽  
Soil Reaction ◽  
Inelastic Behavior ◽  
Guanabara Bay ◽  
Structure Interaction ◽  
Non Linear

Heated pipelines buried in soft clay can develop a very challenging behavior. The thermal expansion of the pipelines normally induces buckles, which will be supported by the passive soil reaction. The buckles of the pipelines in soft clay can generate a non-linear inelastic behavior that is an unstable situation named “snap through”. In such situation the pipeline can jump from a configuration of a few centimeters displacement to another of meters displacement. Once the snap through situation has developed, there is the possibility of a local pipeline buckling, causing the pipeline rupture and as a consequence an oil spill. This paper presents the results obtained during the analysis of the rupture of a buried heated pipeline in the Guanabara Bay of Rio de Janeiro, Brazil. A very sophisticated procedure including a simulation of the thermal mechanical interactions between the soil and the pipeline structure was developed for back analysis of the thermal inelastic pipeline buckling. Computer modeling was carried out using the finite element method considering of the non-linear material behavior of the soil and pipeline, and nonlinear geometrical behavior of the pipeline. A cyclic thermal-mechanical soil-pipeline structure interaction model was the challenging aspect of the simulation, that explains the trigger mechanism of the snap through behavior of heated pipelines, which was responsible for the rupture of the pipeline in Guanabara Bay.

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