Field Full Scale Tests on Longitudinal Pipeline-Soil Interaction

1998 ◽  
Author(s):  
Andrea Cappelletto ◽  
Roberto Tagliaferri ◽  
Gianmario Giurlani ◽  
Giuseppe Andrei ◽  
Giuseppe Furlani ◽  
...  
Keyword(s):  
Practical Implication ◽  
Field Measurements ◽  
Burial Depth ◽  
Direct Shear Tests ◽  
Static Interaction ◽  
Pull Out ◽  
Stress Relieving ◽  
Full Scale Tests ◽  
Different Diameters ◽  
Soil Pipe

Recent research on longitudinal pipe-soil interaction shows that traditional analysis models are inadequate and too conservative, especially when cohesive soils are involved. The practical implication for SNAM, whose network extends over the entire Italian territory where slow ground movements inducing longitudinal soil-pipe interaction are frequent, is that the management of the gas pipeline has to rely mainly on field measurements. The correct assessment of the interaction forces was therefore included as an important part of a wider research program, whose aim is to perform pipe risk analysis by which the structural vulnerability for some SNAM typical scenarios can be quantified as a function of such parameters as the pipe section geometry, the type of soil, the burial depth, the length of pipeline section involved and the magnitude of the soil imposed displacements. Experimental activities specifically regarding longitudinal, static, interaction problems were carried out; in particular pull-out tests were performed on two out of use pipelines, having two different diameters: 8” and 24”. For each site, four different test conditions were investigated where type and compaction state of the material surrounding the pipe varies. The behaviour of the pipe embedded in the original clayey backfill was compared to that observed after such fill was excavated and replaced around the pipe, to simulate conditions after standard stress relieving works. Different fills where then used, made of either granular soil or granulite; this latter was used in order to ascertain the possible benefits of using light artificial materials to mitigate soil-pipe interaction phenomena. Site testing was accompanied by a careful geotechnical investigation both in the field and in laboratory that included direct shear tests of interfaces using coated steel pipe specimens. A comparison between the results obtained and the existing state of the art is presented. This comparison allowed to verify the effectiveness of some interpretative models, and in particular the convenience of adopting effective stress based models rather than pure cohesive ones (i.e. total stress), even in the case of clayey soils.

Response of Buried District Heating Pipelines Under Relative Axial Movements

2014 ◽  
Author(s):  
Michael Huber ◽  
Dharma Wijewickreme
Keyword(s):  
Urban Areas ◽  
Test Chamber ◽  
District Heating ◽  
Cost Effective ◽  
Full Scale ◽  
Cross Sectional ◽  
Pullout Resistance ◽  
Pull Out ◽  
Full Scale Tests ◽  
Soil Pipe

District heating (DH) systems are commonly used in urban areas to distribute thermal energy from central heat sources. Buried pipes, with a composite cross-sectional construction, are used transport a heated medium, usually water. These pipes expand and contract radially and axially due to changing water temperatures, invoking soil-pipe interaction situations during operation, and potentially leading to significant pipeline material strains. A series of full-scale tests were undertaken to specifically investigate the influence of thermal expansion on axial pullout resistance using DH pipes buried in sand in a full-scale soil-pipe interaction test chamber. During testing, the pipe is filled with water that is subjected to temperature changes to simulate field conditions. Axial pipe pull-out tests were conducted after applying a given “heating history” with axial pullout force and displacements recorded. The work leads to better understanding of soil-pipe interaction mechanisms generating currently scarce data needed for robust and cost-effective designs of DH pipe systems.

scholarly journals Shear Strength and Pull-Out Response of Tire Shred-Sand Mixture Reinforced with Deformed Steel Bars

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Beenish Jehan Khan ◽  
Irshad Ahmad ◽  
Hassan Nasir ◽  
Abdullah Abdullah ◽  
Qazi Khawar Gohar
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Friction Angle ◽  
Sand Mixture ◽  
Strain Behavior ◽  
Backfill Material ◽  
Pull Out ◽  
Tire Shreds ◽  
Steel Bars ◽  
Different Diameters

The use of scrap tires in various engineering applications has been extensively explored. The present study has the following aim: to evaluate the suitability of tire-sand mixtures as backfill material based on its shear strength. To achieve this objective, modified Proctor compaction tests were performed on tire shred-sand mixture with mixing proportions by weight of tire shreds and sand (0/100, 20/80, 30/70, and 40/60) using different sizes of tire shreds (50 mm, 75 mm, and 100 mm). Based on the results of the modified Proctor compaction test, the two mixing proportions, i.e., tire shred/sand, 20/80 and 30/70, respectively, were selected. Large-scale direct shear test indicated higher internal friction angle and cohesion values for tire shred-sand mixtures (30/70) with 100 mm tire size (38.5° and 19 kPa) as compared with sand-only backfill material (30.9° and 0 kPa). Based on stress-strain behavior plots, it was indicated that the inclusion of tire shreds imparts ductility to backfill mixtures. To achieve the second objective, the pull-out tests were performed with deformed steel bars of two different diameters (12.7 mm and 15.8 mm) embedded in various backfill mixtures prepared with tire shreds of three different sizes (50, 75, and 100 mm). The pull-out test result indicated that the deformed steel bars exhibit higher pull-out resistance in tire shred-sand mixtures (9.9 kN/m) compared with sand-only backfill material (4.1 kN/m).

scholarly journals The Effect of the Use of Different Types of Cement and Zirconium Post Systems on Endondontically Treated Teeth

2018 ◽  
Vol 6 (9) ◽  
pp. 1732-1736
Author(s):  
Vesna Jurukovska-Shotarovska ◽  
Biljana Kapusevska ◽  
Biljana Evrosimovska
Keyword(s):  
Experimental Study ◽  
Light Transmission ◽  
Resin Cements ◽  
Entire Sample ◽  
Endodontically Treated Teeth ◽  
Pull Out ◽  
Relyx Unicem ◽  
Different Types ◽  
Normal Light ◽  
Different Diameters

BACKGROUND: Prefabricated zirconium upgrading systems were examined to satisfy aesthetic needs in endodontically treated teeth. Endodontically treated teeth, together with non-metallic posts and superstructure, are substructures that enable the production of prosthetic structures that will allow aesthetics, resulting from normal light transmission. To investigate and analyse the retention of zirconium post systems cemented with RelyX Unicem 2 Automix (RLX) cement with Pull-out test. AIM: To examine the retention of zirconium post systems, cemented with Multi-Link Automix (MLA) cement and RelyX Unicem 2 Automix (RLX) cement with Pull-out test. MATERIAL AND METHODS: In this study were used, 120 post systems of the company ZIRIX NORDIN - Switzerland, with different diameters d1 = 1.2, were used: d2 = 1.35, d3 = 1.5, and two types of resin cements: Multilink Automix-Ivoclar (MLA), and RelyX Unicem 2 Automix (RLX) - 3 M ESPE. RESULTS: The analysis of the extraction force in newtons (N) zirconium post systems of Multilink Automix cement according to subgroups of three diameters is consequently 481.3 ± 1.9 vs 462.9 ± 4.5 vs 454.2 ± 2.2. The analysis of the extraction strength in the newtons (N) zirconium post systems of RelyX Unicem 2 Automix cement in the entire sample is 577.9 ± 6.1 N. CONCLUSION: The largest diameter of the posts significantly increases the resistance of fractures compared to the smaller two diameters used in the experimental study.

scholarly journals Evaluation of the Effect of Fixation Angle between Polyaxial Pedicle Screw Head and Rod on the Failure of Screw-Rod Connection

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Engin Çetin ◽  
Mustafa Özkaya ◽  
Ümit Özgür Güler ◽  
Emre Acaroğlu ◽  
Teyfik Demir
Keyword(s):  
Mechanical Properties ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Maximum Load ◽  
Test Results ◽  
Screw Head ◽  
Pull Out ◽  
Flexion Moment ◽  
Polyaxial Screws ◽  
Different Diameters

Introduction.Polyaxial screws had been only tested according to the ASTM standards (when they were perpendicularly positioned to the rod). In this study, effects of the pedicle screws angled fixation to the rod on the mechanical properties of fixation were investigated.Materials and Method.30 vertically fixed screws and 30 screws fixed with angle were used in the study. Screws were used in three different diameters which were 6.5 mm, 7.0 mm, and 7.5 mm, in equal numbers. Axial pull-out and flexion moment tests were performed. Test results compared with each other using appropriate statistical methods.Results.In pull-out test, vertically fixed screws, in 6.5 mm and 7.0 mm diameter, had significantly higher maximum load values than angled fixed screws with the same diameters (P<0.01). Additionally, vertically fixed screws, in all diameters, had significantly greater stiffness according to corresponding size fixed with angle (P<0.005).Conclusion.Fixing the pedicle screw to the rod with angle significantly decreased the pull-out stiffness in all diameters. Similarly, pedicle screw instrumentation fixed with angle decreased the minimum sagittal angle between the rod and the screw in all diameters for flexion moment test but the differences were not significant.

Some Observations on Soil-Pipe Interface Shear Strength in Direct Shear Under Low Effective Normal Stresses and Large Displacements

2016 ◽  
Author(s):  
Ruslan S. Amarasinghe ◽  
Dharma Wijewickreme ◽  
Hisham T. Eid
Keyword(s):  
Shear Strength ◽  
Accurate Determination ◽  
Direct Shear ◽  
Normal Stresses ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Fine Grained ◽  
Direct Shear Tests ◽  
Macro Scale ◽  
Soil Pipe

Experimental work is undertaken at the University of British Columbia (UBC) to study the soil-pipe interface shear strength at levels of shear displacements and effective normal stresses typically encountered in offshore soil-pipe interaction problems. A macro-scale interface direct shear apparatus having a test specimen footprint of 1.72 m × 1.75 m was designed and built for this purpose. The apparatus is capable of testing various soil-pipe interfaces under effective normal stresses in the range of 3 kPa to 6 kPa. A maximum shear displacement of 1.2 m is achievable at rates ranging from 0.1 μm/s to 1 mm/s. Sensors mounted at the interface enable the accurate determination of the effective normal stress at the interface when fully saturated fine-grained soils are tested. This paper presents some observations arising from a series of interface direct shear tests involving fine-grained soils of different plasticity against bare and epoxy coated steel surfaces.

Full-scale field studies of the dynamic response of piles embedded in partially frozen soils

1991 ◽  
Vol 28 (5) ◽  
pp. 708-718 ◽  
Author(s):  
Hans Vaziri ◽  
Yingcai Han
Keyword(s):  
Dynamic Response ◽  
Soil Layer ◽  
Field Measurements ◽  
Field Studies ◽  
Full Scale ◽  
Frozen Soil ◽  
Field Observations ◽  
Practical Applications ◽  
Order Of Magnitude ◽  
Full Scale Tests

The influence of a frozen soil layer on the dynamic response of full-scale concrete piles subjected to strong horizontal excitation was studied. The study undertaken compares the field observations against the theoretical predictions and provides an insight into the role of the yielded zone (boundary zone) in theoretically matching the field observations. The field measurements are used to postulate empirical relationships that can be used under practical conditions to estimate the magnitude of soil separation around piles embedded in cohesive soils as a function of the maximum vibration amplitude. The tests performed indicate that the presence of a frozen soil layer, even at a modest thickness of less than 0.5 m, can significantly influence the dynamic response of piles; the horizontal stiffness of the pile was increased by one order of magnitude, and its resonant frequency was increased by a factor of four compared to the situation with no frozen soil layer. The qualitative and quantitative findings from this study are considered to have practical applications in the design of piles under similar conditions as well as in providing a field validation of the theoretical solutions that have been developed for analyzing the dynamic response of piles. Key words: dynamics, vibration, piles, full-scale tests, frozen soil, modelling, resonance, soil separation, soil yielding.

scholarly journals An Investigation of Pull-Out Force of Semi-Buried Lotus Roots after Hydraulic Scouring

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 706
Author(s):  
Rong Zeng ◽  
Yitao Lin ◽  
Zhihua Wan ◽  
Ming Tu ◽  
Jun Jiao ◽  
...  
Keyword(s):  
Surface Area ◽  
Root Surface ◽  
Root Surface Area ◽  
Burial Depth ◽  
Factors Affecting ◽  
Similar Shape ◽  
Pull Out ◽  
Lotus Root ◽  
Simulation Results ◽  
First Time

Hydraulic scouring is the most effective approach to harvest lotus roots, but its application is largely restricted by the low harvesting rate. After hydraulic scouring, some mature lotus roots are still partially buried in the soil. Therefore, it is highly necessary to develop an appropriate approach to harvest semi-buried lotus roots. In this work, we for the first time studied the interaction between semi-buried lotus roots and soil, as well as analyzing the pull-out process and the factors affecting the pull-out force of semi-buried lotus roots. Firstly, a simple testing platform was designed based on the virtual prototype technology and the tests on pull-out force were conducted on five lotus roots with similar shape but different weights, with the burial depth and pull-out speed as the experimental factors. The results revealed that the maximum pull-out force is not significantly affected by the pull-out speed, whereas it is significantly influenced by the burial depth and the surface area of lotus roots. The maximum pull-out force increased with increasing lotus root surface area and burial depth. In addition, the discrete element method was employed to simulate the pull-out process of lotus root at different pull-out speeds. The simulation results indicated that a higher pull-out speed would result in a greater pull-out force at the same displacement of the lotus root from the soil. Both experimental and simulation results revealed that soil adhesion contributes the most to the pull-out resistance. It was also observed that a slight loosening of semi-buried lotus roots could drastically reduce the pull-out force. These results suggest that some kind of mechanical structure or improvement of water flow can be applied to the existing lotus root harvester to reduce the adhesion between lotus roots and soil. Overall, our findings provide a novel direction for optimizing hydraulic harvesting machines of lotus roots.

A New Pull-Out Test to Study the Bond Behavior of Fiber Reinforced Cementitious Composites

2017 ◽  
Vol 747 ◽  
pp. 258-265 ◽  
Author(s):  
Tommaso D'Antino ◽  
Francesca Giulia Carozzi ◽  
Pierluigi Colombi ◽  
Carlo Poggi
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Pull Out ◽  
The Matrix ◽  
Set Up ◽  
High Strength Fiber ◽  
Fiber Reinforced Cementitious Composites

Fiber reinforced cementitious matrix (FRCM) composites are gaining increasing popularity in the civil engineering community. FRCM composites are comprised of high-strength fiber textiles embedded within inorganic matrices that are responsible for the stress-transfer mechanism between the composite and the substrate. Failure of FRCM composites including one layer of textile is generally reported to be debonding of the fibers from the embedding matrix. Therefore, the bond behavior of the matrix-fiber interface is of critical importance for these types of composites.This paper presents the results of an experimental campaign carried out to investigate the bond behavior of an FRCM composite comprising PBO fibers. Specimens were tested using a newly-developed pull-out test set-up. The results obtained are compared with those obtained by different authors on single-lap direct-shear tests with the same FRCM composite.

Research on Cotton Stalk Harvester Based on Double Roller Type

2014 ◽  
Vol 945-949 ◽  
pp. 286-289
Author(s):  
Zhi Guo Pan
Keyword(s):  
Friction Force ◽  
Cotton Stalk ◽  
Development Status ◽  
Pull Out ◽  
Different Diameters

This paper studies the development status of domestic and foreign cotton stalk harvester. On this basis, a double roller cotton stalk Harvester is designed, which is suitable for small plots. It can pull out the entire cotton stalk through two pairs of reverse rotation of the roller and the forward thrust of tractor. In order to increase the friction force between the roller and the cotton stalk, the two pairs of roller axes are designed with a certain angle and the surface is designed into a rugged, spiral into distribution, which can adapt to the different diameters of cotton stalk harvesting.

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