scholarly journals The Effect of Soil Reinforcement on the Stress and Strain Field Around Underground Square-Shaped Areas and its Internal Lining Efforts in Urban Areas

2018 ◽  
Vol 4 (11) ◽  
pp. 2756 ◽  
Author(s):  
Alireza Darvishpour ◽  
Asadollah Ranjbar ◽  
Amirmohammad Amiri
Keyword(s):  
Urban Areas ◽  
Underground Structure ◽  
Physical Modelling ◽  
Soil Reinforcement ◽  
Soil Parameters ◽  
Stress And Strain ◽  
Horizontal Distance ◽  
Underground Structures ◽  
Finite Element Software ◽  
Before And After

The passage of underground structures from the bottom of the structures on the ground causes a change in the stresses and strains created in the structure as well as the soil environment surrounding the tunnel due to the existence of an interaction between these two sides. In this way, the existence of the surface structure leads to a change in the strain and stress conditions around the tunnel, and in contrast, the tunnel also leads to a change in the stress and settlement around the structures. Therefore, such a reciprocal behavior is very important. In this research, with the help of Abaqus finite element software, two main possible conditions are considered: the creation of an underground structure in the presence of the superstructure, as well as the reverse state of the concept of constructing a building in the state in which the underground structure already exists. One of the subjects studied in this research is the physical modelling effect of the structure, rather than the effect of its wide load on the ground. Other parameters considered in this research are the number of story, the depth of the tunnel, the width of the tunnel, the thickness of the lining, the effect of changes in the soil parameters in the depth and the horizontal distance of the tunnel center from the building center. The results of this research are validated based on the results obtained by other researchers. According to the results obtained in this research, by the increase of the distance between the tunnel center and structure center and depending on the stiffness of the tunnel lining, significant asymmetric stresses are created in the superstructure. The construction of the structure before and after the tunnel construction can affect the unsymmetrical settlement of the structure The stress and strain created in the lining of the tunnel and the surrounding area are also different due to the amount of mobilized force in the reinforcements.

scholarly journals Investigation of Groundwater Withdrawal and Recharge Affecting Underground Structures in the Shanghai Urban Area

2019 ◽  
Vol 11 (24) ◽  
pp. 7162 ◽  
Author(s):  
Yong-Xia Wu ◽  
Tian-Liang Yang ◽  
Pei-Chao Li ◽  
Jin-Xin Lin
Keyword(s):  
Land Subsidence ◽  
Urban Areas ◽  
Water Pressure ◽  
Underground Structure ◽  
Pressure Head ◽  
Groundwater Withdrawal ◽  
Underground Structures ◽  
Groundwater Head ◽  
Increased Risk ◽  
Confined Aquifers

In this paper, the hydrogeological features of Quaternary deposits in Shanghai as well as the characteristics of groundwater withdrawal and recharge in urban areas are investigated. One phreatic aquifer and five confined aquifers (AqI to AqV) are present in Shanghai, and these aquifers are separated by five aquitards. Groundwater withdrawal from confined aquifers has resulted in land subsidence in Shanghai. To control land subsidence, the groundwater withdrawal volume has been decreased, and the groundwater recharge volume has been increased since 1965. Correspondingly, the pressure head in confined aquifers has risen. The groundwater head increases in shallow aquifers may impact underground structures and lead to the following issues: i) an increased risk of water in-rushing hazards caused by confined water pressure during structural excavations and ii) an increased instability risk caused by groundwater buoyancy. Both excavation anti-uprush and underground structure anti-floating are discussed in this paper. Based on the risk possibilities, the anti-uprush of the excavation is divided into six regions, and the structural anti-floating is divided into five regions in urban areas. To avoid geohazards caused by the rise in groundwater head, real-time monitoring of the pressure head in AqII is recommended.

Effect of Blasting on the Adjacent Underground Tunnels

2011 ◽  
Vol 90-93 ◽  
pp. 1870-1878 ◽  
Author(s):  
Zu Song Wu ◽  
Guang Qi Chen ◽  
Kouki Zen ◽  
Kiyonobu Kasama ◽  
Dao Liang Wang
Keyword(s):  
Numerical Simulation ◽  
Underground Structure ◽  
Surrounding Rock ◽  
Tunnel Structure ◽  
Underground Structures ◽  
Economical Method ◽  
Explosive Energy ◽  
Finite Element Software ◽  
Severe Effect ◽  
Blasting Method

The blasting method is regarded as a simple, convenient and economical method for constructing the underground structure, so it is advisable method for many underground structures to construct. But the investigation of the effect of the blasting dynamic load on the vicinal tunnel structure is rare, and the effect of blasting on the vicinal structures cannot be ignored either; sometimes, the effect will cause crack and even collapse in the tunnel liner and surrounding rock. So this paper presented the effect of blasting on the vicinal underground structure in differential cases using the finite element software Midas GTS. The investigation in this paper indicated which case will suffer the more severe effect caused by blast and let us know the vibration principle of the underground structure in differential case, and that will provide the knowledge about the vibration caused by blasting to the design and construction by numerical simulation; additionally, this paper has presented the reinforcement method about inserting the bolt into the surrounding rock to analyze how to resist the effect of the blast load. So from this analysis, it can be noted that the blasting method or the explosive energy will be chosen on the basis of different construction shape, and the reasonable location of the bolt will be adopted in order to reduce the effect of the dynamic on the vicinal tunnel structure.

scholarly journals Influence Analysis of Underground Excavation on the Adjacent Buildings and Surrounding Soil Based on Scale Model Test

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Suhui Yu ◽  
Yongchang Geng
Keyword(s):  
Urban Areas ◽  
Underground Structure ◽  
Scale Model ◽  
Horizontal Distance ◽  
Existing Buildings ◽  
Soil Pressure ◽  
Adjacent Buildings ◽  
Vertical Displacements ◽  
The Impact ◽  
Surrounding Soil

In urban areas, it is common to construct underground structure nearby existing buildings. To investigate the impact of excavation construction on the adjacent existing buildings and surrounding soil, eight parallel scale model tests that considered the process of cut and cover construction are carried out with two kinds of the diameter of support piles, two kinds of the adjacent structure, and two kinds of the relative horizontal distance from the excavation in the laboratory. And, the variations of horizontal and vertical displacements of adjacent buildings and the soil pressure surrounding the excavation and the foundations of existing buildings with different parameters are presented and discussed. Then, the experimental data and the results of eight prototype finite element models are compared and analyzed.

scholarly journals Utilization of Building Information Modeling for Arranging the Structural Kingposts

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 323
Author(s):  
Vachara Peansupap ◽  
Pisal Nov ◽  
Tanit Tongthong
Keyword(s):  
Underground Structure ◽  
Visual Programming ◽  
Information Modeling ◽  
Construction Technology ◽  
Underground Structures ◽  
Building Information Modelling ◽  
Engineering Knowledge ◽  
Building Information ◽  
Rule Based Approach

The kingpost was a vertical element that was used to support the structural strut in the deep excavation. The structural kingpost was commonly arranged by experienced engineers who used two-dimensional construction drawings. Thus, it was still time-consuming and error-prone. Currently, an available construction program has been developed to arrange the structural kingpost by identifying the clash problems in the 3D environment. However, they have a limitation for detecting the clash that was unable to visualize the concurrent clashes between kingpost and many underground structures. Then, the engineer cannot see all the clash incidents with each kingpost and move the kingpost to avoid the clashes successfully. Since the kingpost arrangement was still an inefficient practice that was limited in the visualization aspect, this research used engineering knowledge and advanced construction technology to detect and solve the clashes between kingposts and underground structures. The methodology used engineering knowledge of kingpost arrangement to develop the system modules by using a rule-based approach. Then, these modules were developed into the system by using visual programming of Building Information Modelling (BIM). To test the system, an underground structure from building construction was selected as a case study to apply the developed system. Finally, the finding of this study could overcome human judgment by providing less interaction in the kingpost arrangement and visualization improvement of clash occurrences in the 3D model.

Simple approach to obtain ground amplification motion of surface soil deposits with a radical change of depth

2005 ◽  
Vol 42 (2) ◽  
pp. 491-498
Author(s):  
Dae-Sang Kim ◽  
Kazuo Konagai
Keyword(s):  
Seismic Design ◽  
Surface Soil ◽  
Underground Structure ◽  
Free Field ◽  
Alluvial Soil ◽  
Radical Change ◽  
Simple Approach ◽  
Clear Understanding ◽  
Underground Structures ◽  
Soil Deposits

Earthquake observations at different sites within alluvial soil deposits have demonstrated that the motion of buried underground structures closely follows that of the surrounding soil. Therefore, it is usual in a seismic design process to apply free-field ground displacements through Winkler-type soil springs to an underground structure to evaluate stress patterns induced within its structural members. Using a simplified approach, this paper provides a clear understanding of resonant horizontal ground displacement of and strain in a surface soil deposit with a radical change of depth and of where they occur.Key words: simple approach, seismic design, earthquake, resonance, underground structures.

Impact of adenotonsillectomy on the quality of life of patients operated on at the Hospital de Clínicas, Paraguay

2021 ◽  
pp. 1-7
Author(s):  
Carlos Mena Canata ◽  
Rebeca Noemí Ruiz Vallejos
Keyword(s):  
Quality Of Life ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Rural Areas ◽  
Urban Areas ◽  
Obstructive Sleep ◽  
Significant Difference ◽  
Before And After ◽  
The Impact

The objective of this study is to determine the impact of adenotonsillectomy on the quality of life of postoperative patients.The study is observational, cross-sectional, and retrospective. The files of all postoperative adenotonsillectomy patients in Otorhinolaryngology Service, Hospital de Clínicas, San Lorenzo Paraguay. The Obstructive sleep apnea – 18 questionnaire (OSA 18) was applied, asking patients about symptoms before and after surgery. An effective sample of 143 postoperative patients was obtained. The average age was 6.05 ± 2.08 years, 55.10% (81) were male and 44.89% (66) were female, 65.30% (96) were from urban areas and 34.69% (51) from the rural areas. The t test was performed for means of two paired samples, comparing the results of the Obstructive sleep apnea – 18 questionnaire surveys before and after surgery which presented a significant difference (p <0.05) with a tendency to improve the quality of life after surgery. It has been shown that there is a significant difference, a considerable improvement in the quality of life of patients after adenotonsillectomy.

scholarly journals Overview of Anti-Seismic Researches of Underground Structures

2018 ◽  
Vol 38 ◽  
pp. 03038
Author(s):  
Ran Liao
Keyword(s):  
Research Methods ◽  
Underground Structure ◽  
Seismic Damage ◽  
Urban Rail Transit ◽  
Rail Transit ◽  
Underground Structures ◽  
Transit System ◽  
Urban Rail ◽  
Subway System ◽  
Metro System

With the vigorous development of urban rail transit system, especially the construction of subway system, the safety of subway system draws more and more attention. The study of anti-seismic for underground structures has also become an important problem to be solved in the construction of Metro system. Based on the typical underground structure seismic damage phenomenon, this paper summarizes the seismic characteristics, research methods and design methods of underground structures to offer a guide for engineers.

Residual strength of underground structures in service

2016 ◽  
Vol 53 (6) ◽  
pp. 988-999 ◽  
Author(s):  
Taous Kamel ◽  
Ali Limam ◽  
Claire Silvani
Keyword(s):  
Stress State ◽  
Residual Strength ◽  
Underground Structure ◽  
Numerical Approach ◽  
The Finite Element Method ◽  
Underground Structures ◽  
Weathering Processes ◽  
Working Face ◽  
Metro Tunnel ◽  
Loss Of Strength

Old tunnels suffer from deterioration and it is necessary to assess their residual strength to properly organize their repair and strengthen them. The stress state of underground structures evolves over time, firstly because of the advancement of the working face during construction, then due to gradual changes in soil properties and mechanical properties of materials composing the infrastructures, such as reduction of cohesion, loss of strength and (or) stiffness, etc. These changes are caused by combined actions such as creep and (or) weathering processes as well as the appearance of cracks that induce redistribution of stresses and therefore strains. This study investigates tunnels and galleries of the Paris underground. Macromodeling based on the finite element method allows consideration of different scenarios of tunnel-lining deterioration, specifically at the extrados of the galleries or tunnels. To understand changes in the stress state, and also damage occurrence and associated redistributions (stress and strain), it is necessary to model the delayed deformations. To model the infrastructure behavior, a time-dependency approach has been chosen. This approach can quantify the damage and predict the residual strength of this type of underground structure. An elastic–viscoplastic constitutive model with strain-softening is used to reproduce the appearance of the degraded zones and their behavior. The results obtained with the numerical approach reproduce Paris metro tunnel behavior, corroborate geoendoscopy results, clarify their interpretation, and improve the management of infrastructure repairs.

scholarly journals Prediction of mechanical properties and fatigue life of nano silver paste in chip interconnection

2020 ◽  
Author(s):  
Hui YANG ◽  
Jihui Wu
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Stress And Strain ◽  
Nano Silver ◽  
Finite Element Software ◽  
Flip Chips ◽  
Empirical Correction ◽  
Prediction Of Mechanical Properties

Abstract The simulation of nano-silver solder joints in flip-chips is performed by the finite element software ANSYS, and the stress-strain distribution results of the solder joints are displayed. In this simulation, the solder joints use Anand viscoplastic constitutive model, which can reasonably simulate the stress and strain of solder joints under thermal cycling load. At the same time this model has been embedded in ANSYS software, so it is more convenient to use. The final simulation results show that the areas where the maximum stresses and strains occur at the solder joints are mostly distributed in the contact areas between the solder joints and the copper pillars and at the solder joints. During the entire thermal cycling load process, the area where the maximum change in stress and strain occurs is always at the solder joint, and when the temperature changes, the temperature at the solder joint changes significantly. Based on comprehensive analysis, the relevant empirical correction calculation equation is used to calculate and predict the thermal fatigue life of nano-silver solder joints. The analysis results provide a reference for the application of nano-silver solder in the electronic packaging industry.

scholarly journals The impact of heavy object on an underground structure when falling onto the ground surface

2021 ◽  
Vol 17 (4) ◽  
pp. 425-438
Author(s):  
Oleg V. Mkrtychev ◽  
Yury V. Novozhilov ◽  
Anton Yu. Savenkov
Keyword(s):  
Nuclear Power ◽  
Rocket Engine ◽  
Underground Structure ◽  
Ground Surface ◽  
Civil Defense ◽  
Main Task ◽  
Underground Structures ◽  
Building Collapse ◽  
Protective Structures ◽  
The Impact

At the objects of space infrastructure and at nuclear power facilities there are industrial structures, the main task of which is to protect a person, equipment or machinery from emergencies such as, for example, explosions, falling of various objects, fragments. In accordance with the requirements of the Federal Law On the Protection of the Population and Territories from Natural and Technogenic Emergencies, when calculating such structures, all types of loads corresponding to their functional purpose must be taken into account. So, for structures located in the area of a possible accident and the fall of space rockets, it is necessary to calculate for the fall of the destroyed parts of the rocket engine. For nuclear power plant facilities, such accidents occur when containers and other heavy objects fall on the ground, affecting underground structures located in the ground, and for civil defense protective structures built into the basement floors of buildings, it is necessary to consider situations in which the overlying floors of a building collapse when exposed to there is an air shock wave on them. Therefore, this problem is relevant, and in this study, a finite-element method for calculating an underground structure in a non-linear dynamic setting has been developed when a large overall object collides with the ground.

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