scholarly journals Evaluation of Anthropogenic Substrate Variability Based on Non-Destructive Testing of Ground Anchors

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5131
Author(s):  
Marek Wyjadłowski ◽  
Janusz V. Kozubal ◽  
Zofia Zięba ◽  
Dmitri Steshenko ◽  
Dariusz Krupowies
Keyword(s):  
Rheological Model ◽  
Destructive Testing ◽  
Anthropogenic Origin ◽  
Nonlinear Fitting ◽  
Geostatistical Methods ◽  
Valley Slope ◽  
Ground Anchors ◽  
Slope Excavation ◽  
Load Tests ◽  
Ground Anchor

The purpose of this paper is to describe the variability of soil rheological properties based on research carried out using load tests of ground anchors under complex geotechnical conditions. The heterogeneity of soil should always be considered when designing geotechnical constructions. In the present case, the earthwork created at the Warsaw Slope revealed an embankment of anthropogenic origin, located in a geologically and geomorphologically complex area of the Vistula valley slope. Excavation protection was anchored mainly in soils of anthropogenic origin. When the acceptance tests of the ground anchor were completed, the subsoil randomness was confirmed using nondirect, geostatistical methods. A standard solid rheological model with nonlinear fitting to the data was used. This model was established to describe the creeping activity of the ground anchor more accurately. The characteristics of man-made embankments were described using the parameters obtained with the rheological model of the subsoil.

scholarly journals The Historical Earthworks of the Warsaw Citadel

2020 ◽  
Vol 12 (18) ◽  
pp. 7695
Author(s):  
Marek Wyjadłowski ◽  
Janusz Kozubal ◽  
Wojciech Damsz
Keyword(s):  
Rheological Model ◽  
Industrial Revolution ◽  
National Standard ◽  
Model Parameters ◽  
Destructive Testing ◽  
Ground Anchors ◽  
Standard Procedures ◽  
Load Tests ◽  
Geotechnical Tests ◽  
Military Engineering

In this study, we analyzed the methods and technologies used for constructing earthworks and military engineering in the latter period before the industrial revolution in Poland. The research object, the Warsaw Citadel, is a source of knowledge about military heritage from the aspect of conservation and protection of specific engineering achievements, which were dictated by early Russian geopolitical doctrine. Within the framework of the ongoing project of material heritage protection and popularization of history, the fortress has been transformed into a modern museum building. The new symbolic message of architecture was redefined, leaving behind the gloomy dominance elements in the scenery of the nearby city. In this study, reception tests of ground anchors were used for analysis. They were treated as a tool to determine the heterogeneity of fortification of historical earthworks. In the presented calculation procedure, limitations in the availability of geotechnical tests were overcome. Geological terrain layout and embankment excavation technology significantly impacted their quality and reliability. Currently, the embankments are slashed with anchored retaining walls. Ground anchors were used at short distances and were tested according to the national standard procedures. The results of the load tests are based on the physical properties of the subsoil, the conditions of contact with the supporting elements of the anchors, and the material properties. The soil interaction with the anchors is described using a rheological model, the constants of which were obtained using a fractional derivative model. The spatial variability of the rheological model parameters is presented using theoretical semivariograms matching the empirical data. The semivariograms explain the spatial correlation of the tested constants of the rheological model of the substrate with the anchors. The results of non-destructive testing were influenced by factors such as time and consolidation processes. The obtained results allowed us to directly draw conclusions about the repetitiveness of embankment features and indirectly about the quality of their construction.

scholarly journals Model Test Research on Bearing Mechanism of Underreamed Ground Anchor in Sand

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Gang Guo ◽  
Zhong Liu ◽  
Aiping Tang ◽  
Yibing Deng ◽  
Jiqiang Zhang
Keyword(s):  
Fiber Bragg Grating ◽  
Model Test ◽  
Interaction Mechanism ◽  
Measuring Method ◽  
Total Resistance ◽  
Ground Anchors ◽  
Deformation State ◽  
Bearing Force ◽  
Fbg Sensors ◽  
Ground Anchor

To improve the capacity of ground anchors, scholars and engineers worldwide have developed various types of underreamed anchors with expanded anchor parts. Underreamed anchors have a completely different mechanism from traditional shaft anchors. The expanded section of an underreamed anchor induces an end bearing force to endure the uplift force similar to a reversed pile. Therefore, the total resistance of an underreamed anchor includes friction and end bearing force. To clarify the bearing mechanism of underreamed anchors, a series of model tests were performed using fiber Bragg grating (FBG) sensors and the photogrammetry measuring method. Based on the tests, the distribution and development of the friction and end bearing force of the underreamed anchor model were acquired by the FBG sensors when being pulled out. Moreover, the deformation state of the soil around the anchor model was observed by the digital photogrammetry measuring method. Finally, the interaction mechanism between an underreamed anchor and surrounding sand was obtained, which was identified as the inherent reason for the distribution and development law of the resistance of the underreamed anchor in sand.

scholarly journals Rutting Prediction Model of Asphalt Mixture Based on the Triaxial Repeated Load Test

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jie Ji ◽  
Meng Chen ◽  
Zhi Suo ◽  
Jianming Wei ◽  
Jiani Wang ◽  
...  
Keyword(s):  
Prediction Model ◽  
Rheological Model ◽  
Asphalt Mixture ◽  
Load Test ◽  
Modified Asphalt ◽  
Load Tests ◽  
Repeated Load ◽  
Direct Coal Liquefaction ◽  
Coal Liquefaction Residue ◽  
Styrene Butadiene

This study establishes a more reasonable and effective rutting prediction model called the quadratic modified Burgers rheological model by considering dynamic loads. Use ABAQUS to simulate the rutting depths through the existing Burgers model and the quadratic modified model and compare with the measured values of the multitemperature and load rutting tests and triaxial repeated load tests. The real tests were conducted on four asphalt mixtures, including SK-90 asphalt mixture, styrene-butadiene-styrene (SBS) modified asphalt mixture, direct coal liquefaction residue (DCLR) modified asphalt mixture, and compound DCLR modified asphalt mixture. The results showed that the range of error ratio and residual sum of squares between simulated and measured rutting depth based on the two different models are 5–35%/5.0–8.74% and 3–15%/0.9–3.1%, respectively, which show that the quadratic modified Burgers rheological model has a more accurate prediction.

scholarly journals Predicting load on ground anchor using a metaheuristic optimized least squares support vector regression model: a Taiwan case study

2020 ◽  
Author(s):  
Min-Yuan Cheng ◽  
Minh-Tu Cao ◽  
Po-Kun Tsai
Keyword(s):  
Least Squares ◽  
Support Vector Regression ◽  
Influential Factors ◽  
Percentage Error ◽  
Support Vector ◽  
Support Vector Regression Model ◽  
Symbiotic Organisms Search ◽  
Proper Actions ◽  
Ground Anchors ◽  
Ground Anchor

Abstract Failure of ground anchor is a major cause of landslides and severe natural hazards, especially in the highly developed mountainous areas such as New Taipei City. Accurately estimating load on ground anchors is thus essential for evaluating the stability status of slope to prevent landslide from happening. This study first employed correlation analyses to identify possible influential factors of load on ground anchors. Second, various artificial intelligence models were used to map the relationship of the found influencing factors with the current load on ground anchors. The results indicated that the symbiotic organisms search-optimized least squares support vector regression (SOS-LSSVR) model had the optimal accuracy by earning the smallest value of mean absolute percentage error (9.10%) and the most outstanding value of correlation coefficient (R = 0.988). The study applied the established inference model for the real case of estimating load on un-monitoring ground anchors. The analyzed results strongly advised administrators to conduct site surveying and patrolling more frequently to take early proper actions. In summary, the obtained results have demonstrated SOS-LSSVR as an effective alternative for the conventional subjective evaluation methods, which is able to rapidly provide accurate values of load on un-monitoring ground anchors.

scholarly journals THE LOAD-DISPLACEMENT BEHAVIOUR OF GROUND ANCHORS IN FINE GRAINED SOILS

2018 ◽  
Vol 16 ◽  
pp. 18
Author(s):  
Juraj Chalmovský ◽  
Lumír Míča
Keyword(s):  
Load Transfer ◽  
Progressive Failure ◽  
Back Analysis ◽  
Material Model ◽  
Experimental Program ◽  
Structural Element ◽  
Fine Grained ◽  
Ground Anchors ◽  
Load Tests ◽  
Transfer Method

Ground anchors represent an important structural element in the area of geotechnical engineering. Despite their extensive usage, a design process of these elements is usually performed using simple empirical and semi-empirical methods, neglecting several important influencing factors. This paper gives an analysis of the factor of non-uniform distribution of skin friction resulting in a progressive failure of ground anchors. First, the finite element method in combination with a material model involving regularized strain softening is utilized. Next, an experimental program, including several investigation anchor load tests, was carried out. The goal of this program was to confirm preliminary conclusions drawn from numerical studies and to obtain relevant data for further back analysis. After, there is then described a newly developed application based on the load transfer method, in which all the findings from numerical computations and experimental measurements are incorporated.

scholarly journals Ground anchors corrosion - the beginning of the end

2018 ◽  
Vol 195 ◽  
pp. 03001
Author(s):  
Hung-Jiun Liao
Keyword(s):  
Status Quo ◽  
Humid Climate ◽  
Corrosion Condition ◽  
Ground Anchors ◽  
Maintenance Program ◽  
The Status ◽  
Inspection And Maintenance ◽  
Anchor Design ◽  
Ground Anchor

Ground anchor corrosion is a common problem for anchored slopes in Taiwan. It is partly due to the humid climate condition and abundant groundwater in the slope and partly due to poor corrosion protection of anchor design and construction. In 2010, an anchored slope at Taiwan National Freeway No. 3 failed suddenly after 13 years of service. It buried 3 cars and killed 4 people. It caught the public’s attention and initiated the island-wide program on over hauling the anchors slopes in Taiwan. Since this event, the Ministry of Transportation and Communication (MOTC) of Taiwan government had launched an extensive inspection and maintenance program for the existing anchored slopes along the freeways, highways, and railways. Totally, more than 100,000 ground anchors had been inspected. This paper will evaluate the findings from this inspection program. It includes (1) the status quo of the anchors regarding the corrosion condition and the residual load that remained on the existing anchors; (2) remedial measures taken to sustain the serviceability of existing corroding anchors; (3) measures taken to enhance the long-term durability of new anchors without changing the strand material and the practice of anchor construction commonly used by the local contractors.

scholarly journals Strain Measurement Distributed on a Ground Anchor Bearing Plate by Fiber Optic OFDR Sensor

2018 ◽  
Vol 8 (11) ◽  
pp. 2051 ◽  
Author(s):  
Yong-Seok Kwon ◽  
Dae-Cheol Seo ◽  
Bo-Hun Choi ◽  
Min Jeon ◽  
Il-Bum Kwon
Keyword(s):  
Fiber Optic ◽  
Tensile Force ◽  
Tunable Laser ◽  
Laser Source ◽  
Bearing Plate ◽  
Ground Anchors ◽  
Optical Frequency Domain Reflectometry ◽  
Frequency Domain Reflectometry ◽  
The Difference ◽  
Ground Anchor

The safety of soil slopes reinforced by ground anchors can be evaluated by monitoring the tensile force of the anchors. The tensile force of ground anchors can be determined by measuring the strain of the bearing plate that transfers the tensile force of the anchor to the ground. Therefore, in order to investigate the relation between the strain of the bearing plate and the tensile force of a ground anchor, the strain distributed on the bearing plate was measured by a fiber optic OFDR (optical frequency domain reflectometry) sensor, which was fabricated by a tunable laser source, auxiliary interferometer, and main interferometer. This OFDR sensor was operated through a sweep range of 500 GHz with a spatial resolution of 0.2 mm, and a strain accuracy of approximately 4 με, considering the system noise when operating in 5-cm segments. The sensing fiber was circularly bonded onto the bearing plate using epoxy, and the distributed strain was measured on the bearing plate while increasing the load up to 10 tons. From the experimental results, the difference between the strain near the anchor head and the strain at the far site is significant in the region where compression strain is dominant. However, such a tendency did not appear in areas where bending strain dominates. Therefore, in order to monitor an anchor tensile force, it is necessary to carefully study the calibration factor between the anchor tensile force and the strain of the bearing plate.

scholarly journals ANALISIS STABILITAS LERENG BATUAN DENGAN METODE PERKUATAN GROUND ANCHOR & SOIL NAILING DI LABUAN BAJO, NTT

2018 ◽  
Vol 1 (1) ◽  
pp. 102
Author(s):  
Lois Caroline Setiawan ◽  
Gregorius Sandjaja Sentosa ◽  
Ali Iskandar
Keyword(s):  
Back Analysis ◽  
Soil Nailing ◽  
Ground Anchors ◽  
Ground Anchor

Stabilitas lereng yang akan ditinjau berada di daerah Labuan Bajo, Nusa Tenggara Timur. Bahaya longsor yang dapat terjadi di sekitar lereng sudah dapat teridentifikasi sejak awal perencanaan, namun hal tersebut diabaikan oleh pihak terkait sehingga penggalian tanah dilakukan secara langsung dengan sudut kemiringan lereng 70o dengan tinggi lereng >20 m tanpa adanya perkuatan. Sehingga pada tanggal 22 Agustus 2017 terjadi longsor yang menyebabkan munculnya retakan pada tepi jalan raya. Maka, diperlukan back analysis untuk memperoleh kestabilan lereng. Perkuatan yang digunakan adalah ground anchors dan soil nailing dengan sudut kemiringan pemasangan 30o dan pemasangan dilakukan setiap jarak 2 m. Back analysis ini dibantu dengan 2 program yaitu Plaxis 2D dan Geoslope Slope/W dengan kondisi undrained dan drained. Setelah dilakukan perkuatan, diperoleh nilai keamanan pada program Plaxis 2D adalah 2.7 untuk kondisi undrained dan 2.4 untuk kondisi drained. Selain itu, pada program Plaxis 2D akan menghasilkan nilai deformasi dan gaya tarik yang terjadi pada masing-masing perkuatan. Sedangkan pada program Slope/W hanya menghasilkan pola keruntuhan dan nilai keamanan. Nilai keamanan yang diperoleh untuk kondisi undrained berkisar 2.5 dan kondisi drained berkisar 2.2-2.4.

scholarly journals Application of the theory of limit analysis for the study of the behavior of the ground anchor in homogeneous soil

2019 ◽  
Vol 14 (2) ◽  
pp. 73-86
Author(s):  
Feriel Mekki ◽  
Mohamed Meksaouine
Keyword(s):  
Limit Analysis ◽  
Granular Medium ◽  
Collapse Load ◽  
Ground Anchors ◽  
Tensile Forces ◽  
Homogeneous Soil ◽  
Ground Anchor ◽  
Kinematic Approach

AbstractGround anchors are devices used in many types of structures (on shore and offshore constructions); they can be oriented at different inclinations. Their roles are to resist tensile forces, stabilize and restrain the movement of engineered structure. The objective of this study is to propose a model which represents the mechanism of rupture of homogeneous soil (granular medium) around a single inclined ground anchor when it is tensioned and the determination of the collapse load thanks of the theory of limit analysis based on the kinematic approach in the case of criterion of Mohr-Coulomb taking into account of the mobilization of the soil in abutment in reaction to the loading.

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