Investigation of soil displacements caused by the press-in process for close-ended model piles using an imaging technique

2020 ◽  
Vol 17 (2) ◽  
pp. 2-15
Author(s):  
Ye Lu ◽  
Yun Jiang ◽  
Xiaoyong Wang
Keyword(s):  
Urban Areas ◽  
Image Correlation ◽  
Underground Structures ◽  
Squeezing Effect ◽  
Displacement Fields ◽  
Soil Displacement ◽  
Pile Penetration ◽  
The Press ◽  
Vertical Displacements ◽  
Median Particle

In recent years, installing piles using the press-in method has gained popularity in urban areas. However, pushing piles into the ground squeezes the surrounding soils and consequently causes a disturbance or even damage to the underground structures and facilities close by. In order to investigate the squeezing effect incurred by press-in piling, a series of model tests were performed. The soil displacement field was captured using a non-contact technique called digital image correlation (DIC), and the horizontal soil stresses were measured by mini pressure cells. Analyses of the soil displacement fields showed that the pile press-in process caused different soil displacement paths at different depths and locations. The development of horizontal soil stresses correlated well with the horizontal and vertical displacements. A thin disturbance layer could be observed along the pile-soil interface and it was about 7.4-11.1 D50 in thickness (D50, median particle size). At the end, the soil displacements caused by pushing the model pile with different pile shoes were analyzed and compared, and the analyses showed that a greater shoe angle resulted in greater disturbance to the surrounding soils. However, the influence of the pile shoe angle became less substantial with the increase of the pile penetration depth.

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.

Geodetic benchmark displacement measurements following the 2020 Petrinja earthquake in Croatia

2021 ◽  
Author(s):  
Branko Kordić ◽  
Matija Vukovski ◽  
Marko Budić ◽  
Marko Špelić ◽  
Josip Barbača ◽  
...  
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Field Research ◽  
Future Research ◽  
Postseismic Deformation ◽  
Vertical Displacements ◽  
Geodynamic Processes ◽  
Set Up ◽  
Deformation Area ◽  
Absolute Shift

<p>The earthquake with magnitude ML=6.2 that occurred on 29th December 2020 has caused significant material damage to objects and infrastructure in the towns of Petrinja, Sisak,Glina and the surrounding area. According to the satellite interferometry data, the coseismic and postseismic deformation area covers around 500 square kilometers. The existing geodetic benchmarks have been set in the affected towns, and their coordinates have been determined based on previous GPS campaigns. The GPS network was set up and adjusted at the State Geodetic Administration's request for geodetic monitoring of infrastructure and cadastral projects. These points are not primarily intended for high accuracy measurements at the level of a few millimeters, so their accuracy and the absolute shift concerning geodynamic processes in the region should be taken into account. Nevertheless, the data obtained by their observation after the earthquake can provide valuable information about the horizontal and vertical displacements with a certain level of confidence. The field survey has detected disappearance of a large number of benchmarks and some valuable information has been lost. Still, 58 points were found and observed and it has been concluded that 52 points are reliable and can be used for future research. Because the network of benchmarks is not developed in rural areas, there is a gap in the distribution of benchmarks in affected area. Therefore, the additional data was collected using the benchmarks established for the engineering and cadastral projects and studies. From a total of 67 points that have been found and observed, 42 points will be used. Along with the data collected in urban areas, there will be a total of 94 benchmarks. The accuracy of the geodetic benchmark measurements is at the centimeter level, while the values of deformation are at the level of a few decimeters. Therefore, the obtained data can be used to better assess the displacement recorded during the 29 December 2020 event. In the future, field research will focus on finding additional benchmarks to reach a better spatial distribution.</p>

Steel Buildings' Seismic and Interaction Behavior, Under Different Shapes of Tunnel Drilling

2016 ◽  
Vol 7 (2) ◽  
pp. 1-23 ◽  
Author(s):  
Arash Rostami ◽  
Hamid Alielahi ◽  
Abdoreza Sarvghad Moghadam ◽  
Mahmood Hosseini
Keyword(s):  
Urban Areas ◽  
Steel Structures ◽  
Urban Environments ◽  
Steel Buildings ◽  
Underground Structures ◽  
Residential Areas ◽  
Earthquake Records ◽  
Structural Responses ◽  
Different Shapes ◽  
And Behavior

Development of civil engineering science has introduced tunneling as an important option in reducing the traffic volume of urban environments. Digging tunnels, in every depth, causes changes in the surface ground structure; tunneling in urban areas, especially when has passed through the residential areas has its own particular importance; therefore, having knowledge about tunnels' behavior and effects of diggings is necessary, and in order to prevent unpredictable damages to the structures is one of the requirements of designing. The performance and behavior of underground structures have been studied by many researchers, but the effects of tunneling on earthquake records and its effects on structures above the ground has taken less attention. This study will try to check earthquake record changes and their impact on steel structures located on top part of the tunnels, and has done this issue with digging some circular tunnels. The results indicate that, tunneling alters the earthquake records and also has affections on structural responses.

scholarly journals Identification of the Mechanical Properties of Superconducting Windings Using the Virtual Fields Method

2010 ◽  
Vol 24-25 ◽  
pp. 379-384
Author(s):  
J.H. Kim ◽  
F. Nunio ◽  
Fabrice Pierron ◽  
P. Vedrine
Keyword(s):  
Least Square Method ◽  
Numerical Differentiation ◽  
Tensile Tests ◽  
Least Square ◽  
Image Correlation ◽  
Stereo Image ◽  
Correlation Technique ◽  
Virtual Fields Method ◽  
Displacement Fields ◽  
Full Field

Tensile tests were performed in order to identify the stiffness components of superconducting windings in the shape of rings (also called ‘double pancakes’). The stereo image correlation technique was used for full-field displacement measurements. The strain components were then obtained from the measured displacement fields by numerical differentiation. Because differentiation is very sensitive to spatial noise, the displacement maps were fitted by polynomials before differentiation using a linear least-square method. Then, in the orthotropy basis, the four in-plane stiffnesses of the double pancake were determined using the Virtual Fields Method.

scholarly journals Investigation by Digital Image Correlation of Mixed Mode I and II Fracture Behavior of Metallic IASCB Specimens with Additive Manufactured Crack-Like Notch

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 400 ◽  
Author(s):  
Ivo Campione ◽  
Tommaso Maria Brugo ◽  
Giangiacomo Minak ◽  
Jelena Janković Tomić ◽  
Nebojša Bogojević ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Selective Laser Sintering ◽  
Local Stress ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Mode I ◽  
Displacement Fields

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.

scholarly journals Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Hao Wu ◽  
Guoyan Zhao ◽  
Weizhang Liang ◽  
Enjie Wang ◽  
Shaowei Ma
Keyword(s):  
Fracture Behavior ◽  
Horizontal Displacement ◽  
Image Correlation ◽  
Propagation Mechanism ◽  
Shear Cracks ◽  
Compression Tests ◽  
Displacement Fields ◽  
Red Sandstone ◽  
Tensile Cracks ◽  
Dic Technique

Failure of underground structures, especially intersections, becomes more severe as the depth increases, which poses a new challenge for the safe construction and operation of deep rock engineering. To investigate the mechanical properties and fracture behavior of rock with an intersecting hole under compressive loads, a series of uniaxial compression tests was carried out on cuboid red sandstone specimens containing an intersecting hole with three types of shapes by digital image correlation (DIC) technique. The results showed that the existing hole inside specimens leads to almost a 50% reduction of mechanical parameters from that of intact ones, and this weakening effect is associated with the shapes of holes. Failure of specimens is a progressive process in which cracks, i.e., primary tensile cracks, secondary tensile cracks, and shear cracks, initiate from stress concentration zones, propagate along certain direction, and coalesce with each other into macrofractures. Both the real-time principal strain fields and horizontal displacement fields of specimens under compression could be visually displayed by DIC system, and they were in good consistency in characterizing the fracture behavior. Moreover, the propagation characteristics of primary tensile cracks were studied further by quantitatively analyzing the strain variation during the loading process, and the propagation mechanism of “open-close-reopen” of primary tensile cracks was explained in detail.

scholarly journals Chronological reflection on monitoring urban areas subsidence due to groundwater extraction

2019 ◽  
Vol 85 ◽  
pp. 07015 ◽  
Author(s):  
Alina Radutu ◽  
Radu Constantin Gogu
Keyword(s):  
Land Subsidence ◽  
Urban Areas ◽  
Urban Expansion ◽  
Groundwater Withdrawal ◽  
Groundwater Extraction ◽  
Monitoring Methods ◽  
Vertical Displacements ◽  
Order Of Magnitude ◽  
History Of ◽  
Subsidence Monitoring

Land subsidence affects urban areas worldwide. Sometimes it could be driven by intensive groundwater withdrawal to assure different urban needs and functionalities. Some of these urban areas have a long history of subsidence that covers almost a century. The aim of this paper is to present the evolution of several urban areas affected by land subsidence, the methods used to monitor vertical displacements along the decades in relationship to the groundwater extraction associated to the urban expansion, and the mitigation techniques used for countering the effects of intensive groundwater withdrawal. Even the originally applied subsidence monitoring methods (such as geometric levelling) are still very sensitive, in terms of time consuming, covered area, and financial effort, these methods might be complemented by new methods based on Synthetic Aperture Radar Interferometry (InSAR). InSAR methods show also a significant progress during the last decades when considering the subsidence sensed order of magnitude.

scholarly journals Study of size effect using digital image correlation

2015 ◽  
Vol 8 (3) ◽  
pp. 323-340 ◽  
Author(s):  
A. H. A. SANTOS ◽  
R. L. S. PITANGUEIRA ◽  
G. O. RIBEIRO ◽  
R. B. CALDAS
Keyword(s):  
Digital Image Correlation ◽  
Size Effect ◽  
Digital Image ◽  
Concrete Beams ◽  
Image Correlation ◽  
Displacement Fields ◽  
Bending Tests ◽  
Three Point Bending ◽  
New Methods ◽  
Dic Technique

Size effect is an important issue in concrete structures bearing in mind that it can influence many aspects of analysis such as strength, brittleness and structural ductility, fracture toughness and fracture energy, among others. Further this, ever more new methods are being developed to evaluate displacement fields in structures. In this paper an experimental evaluation of the size effect is performed applying Digital Image Correlation (DIC) technique to measure displacements on the surface of beams. Three point bending tests were performed on three different size concrete beams with a notch at the midspan. The results allow a better understanding of the size effect and demonstrate the efficiency of Digital Image Correlation to obtain measures of displacements.

Digital Image Correlation Based Method of Crack Growth Rate and Fracture Toughness Measurements on Mini-Samples

2013 ◽  
Vol 586 ◽  
pp. 96-99
Author(s):  
Tomasz Brynk ◽  
Anatolii Laptiev ◽  
Oleksandr Tolochyn ◽  
Zbigniew Pakiela
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Optical Measurements ◽  
Displacement Fields ◽  
Strain Measurements ◽  
Special Approach ◽  
Tip Position ◽  
Sintering Method

Modern materials fabrication methods which utilize severe plastic deformation (SPD) do not often allow to obtain enough volume of material to prepare standardized samples for mechanical tests. Therefore, there is a need for mini-samples testing. Mini-samples tests require special approach in terms of precise strain measurements. Accurate strain measurements may be achieved by means of non-contact optical method, namely Digital Image Correlation (DIC). The aim of this work is to present the methodology and results of mini-samples tests in which displacement fields measurements performed by means of DIC and inverse method were utilized for calculation of stress intensity factors and crack tip position tracking. The influence of the subarea of optical measurements for which calculation were performed on the calculations results has been investigated during tests in SPD processed Al alloys and brittle WC-Co sinters produced by means of impact sintering method.

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