Response of buried steel pipelines subjected to relative axial soil movement

2009 ◽  
Vol 46 (7) ◽  
pp. 735-752 ◽  
Author(s):  
Dharma Wijewickreme ◽  
Hamid Karimian ◽  
Douglas Honegger
Keyword(s):  
Earth Pressure ◽  
Axial Direction ◽  
Full Scale ◽  
Interface Shear ◽  
Dense Sand ◽  
Pullout Resistance ◽  
Soil Movement ◽  
Pullout Testing ◽  
Research Findings ◽  
Dry Sand

The performance of buried steel pipelines subjected to relative soil movements in the axial direction was investigated using full-scale pullout testing in a soil chamber. Measured axial soil loads from pullout testing of pipes buried in loose dry sand were comparable to those predicted using guidelines commonly used in practice. The peak values of axial pullout resistance observed on pipes buried in dense dry sand were several-fold (in excess of 2 times) higher than the predictions from guidelines; the observed high axial pullout resistance is primarily due to a significant increase in normal soil stresses on the pipelines, resulting from constrained dilation of dense sand during interface shear deformations. This reasoning was confirmed by direct measurement of soil stresses on pipes during full-scale testing and numerical modeling. The research findings herein suggest that the use of the coefficient of lateral earth pressure at-rest (K0) to compute axial soil loads, employing equations recommended in common guidelines, should be undertaken with caution for pipes buried in soils that are likely to experience significant shear-induced dilation.

Tension tests on smooth and rough model piles in dry sand

1999 ◽  
Vol 36 (4) ◽  
pp. 746-753 ◽  
Author(s):  
Ahmed Shlash Alawneh ◽  
Abdallah I. Husein Malkawi ◽  
Husein Al-Deeky
Keyword(s):  
Surface Roughness ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Dense Sand ◽  
Shaft Resistance ◽  
Placement Method ◽  
Rough Model ◽  
Model Pile ◽  
Smooth Model ◽  
Dry Sand

In order to delineate the significant variables affecting the ultimate uplift shaft resistance of a pile in dry sand, a testing program comprising 64 pullout tests was conducted on open- and closed-ended rough and smooth model piles of two sizes (41 and 61 mm outside diameter). The model piles were installed in medium dense and dense sand to an embedded depth of 0.8 m using two methods of pile placement, static jacking and driving. A rigid steel box measuring 1.1 × 1.1 × 1.3 m was used as a sand container. The results obtained from this study indicated that pile placement method, initial sand condition, pile surface roughness, and pile end type are all significant variables (given in descending order) affecting the ultimate uplift shaft resistance of a single pile in dry sand. Overall, the closed-ended piles showed a 24% increase in shaft resistance compared with the open-ended piles and the average unit shaft resistance of the driven model pile was 1.33 times that of the jacked model pile in the dense sand condition and 1.52 times that of the jacked model pile in the medium dense sand condition. Depending on the test variables, the rough model piles tested in this study experienced a 12-54% increase in capacity compared with the smooth model piles. Also, the lateral earth pressure coefficient values for the rough model piles were greater than those for the smooth model piles. This suggests that part of the increase in capacity due to pile surface roughness is attributed to an increase in the radial effective stress during tensile loading.Key words: piles, shaft resistance, pile placement method, smooth pile, rough pile.

Full-Scale Field Trials of Tire Shreds as Lightweight Retaining Wall Backfill Under At-Rest Conditions

1998 ◽  
Vol 1619 (1) ◽  
pp. 64-71 ◽  
Author(s):  
Jeffrey J. Tweedie ◽  
Dana N. Humphrey ◽  
Thomas C. Sandford
Keyword(s):  
Retaining Wall ◽  
Fluid Pressure ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Full Scale ◽  
Wall Friction ◽  
Test Facility ◽  
Design Parameters ◽  
Interface Shear ◽  
Tire Shreds

A 4.88-m (16-ft), full-scale retaining wall test facility was constructed to investigate the use of tire shreds as backfill for conventional retaining walls. The facility can test backfill at at-rest and active conditions and is instrumental for measuring horizontal stress and interface shear. Tire shreds from three suppliers were tested. The results for at-rest conditions are presented. The average at-rest horizontal stress for tire shreds was about 45 percent less than expected for conventional granular backfill. Moreover, the at-rest horizontal stress was about the same for tire shreds from the three suppliers. Design parameters were developed by using two procedures. The first used the coefficient of lateral earth pressure and the other was based on equivalent fluid pressure. The horizontal and shear forces acting on the concrete face of the wall were used to determine the angle of wall friction, which ranged from 30° to 32° for tire shreds from the three suppliers.

Load-strain-displacement response of geosynthetics in monotonic and cyclic pullout

1998 ◽  
Vol 35 (2) ◽  
pp. 183-193 ◽  
Author(s):  
D M Raju ◽  
R J Fannin
Keyword(s):  
Relative Displacement ◽  
Cyclic Loads ◽  
Normal Stresses ◽  
Constant Ratio ◽  
Pullout Resistance ◽  
Maximum Resistance ◽  
Constant Rate ◽  
Pullout Testing ◽  
Pullout Behaviour ◽  
Cyclic Dynamic

Mobilization of the pullout resistance of geosynthetics in monotonic and cyclic modes is described from both displacement- and load-controlled tests performed at normal stresses in the range 4-17 kPa. The tests were performed on three geogrids and two geomembranes embedded nearly 1.0 m in a uniformly graded sand. Results for load-controlled tests at a constant rate of 0.25 kN/(m ·min-1), followed by several series of load cycles of increasing amplitude, are compared with displacement-controlled tests at a constant rate of 0.5 mm/min. In general the geogrids behave as an equivalent textured sheet. Pullout behaviour, and especially the incremental displacement mobilized at cyclic loads close to the maximum resistance, is found to vary with type of geogrid. In only one case was cyclic pullout resistance of a grid found to exceed the monotonic resistance. A comparison of the cyclic and monotonic response yields a constant ratio of pullout resistance at large displacement, but one which is not unique to a particular specimen. Cyclic strains of decreasing amplitude are mobilized along a test specimen, with most of the necessary relative displacement occurring close to the loaded end and the embedded end showing little response.Key words: pullout testing, monotonic, cyclic, dynamic, geosynthetics, reinforced walls.

Full-scale shake table investigation of bridge abutment lateral earth pressure

2009 ◽  
Vol 42 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Patrick Wilson ◽  
Ahmed Elgamal
Keyword(s):  
Large Scale ◽  
Dynamic Pressure ◽  
Inertial Force ◽  
Earth Pressure ◽  
Shake Table ◽  
Passive Force ◽  
Dense Sand ◽  
Lateral Earth Pressure ◽  
Bridge Abutment ◽  
Force Displacement

During strong seismic excitation, passive earth pressure at the abutments may provide resistance to longitudinal displacement of the bridge deck. The dynamic pressure component may also contribute to undesirable abutment movement or damage. Current uncertainty in the passive force-displacement relationship and in the dynamic response of abutment backfills continues to motivate large-scale experimentation. In this regard, a test series is conducted to measure static and dynamic lateral earth pressure on a 1.7 meter high bridge abutment wall. Built in a large soil container, the wall is displaced horizontally into the dense sand backfill, in order to record the passive force-displacement relationship. The wall-backfill system is also subjected to shake table excitation. In the conducted tests, lateral earth pressure on the wall remained close to the static value during the low to moderate shaking events (up to about 0.5g). At higher levels of input acceleration, a substantial portion of the backfill inertial force started to clearly act on the wall.

Effect of Wetting on the Pullout Resistance of Grouted Soil Nails

2012 ◽  
Vol 226-228 ◽  
pp. 1304-1307
Author(s):  
Jason Y. Wu ◽  
Jr Min Chang
Keyword(s):  
Fine Sand ◽  
Shear Resistance ◽  
Test Results ◽  
Pullout Capacity ◽  
Interface Shear ◽  
Soil Nails ◽  
Soaking Time ◽  
Pullout Resistance ◽  
Soil Nail ◽  
Pullout Tests

In this research, laboratory pullout tests were conducted on grouted soil nails to study the effect of wetting on the interface shear resistance between nail and soil during pullout. Deformed bars with equal size to the true soil nails were used as model nails. The soil used was silty fine sand collected at the site and prepared to a very dense condition. Rainfall infiltration was simulated using duplicated soil nails inundated by water for different periods. Test results indicated that the peak pullout resistance strongly decreases upon wetting, with a reduction of about 60% after soaking for 28 days. However, the experiments showed that there is a threshold water content (or soaking time) beyond which the effect of infiltration on the pullout resistance is reduced. The laboratory protocols developed in this study offered an easy scheme for the prediction of the pullout capacity of a grouted soil nail upon wetting.

Soil Loads on Polyethylene Natural Gas Pipelines Subjected to Relative Axial Ground Displacements

2007 ◽  
Author(s):  
Lalinda Weerasekara ◽  
Dharma Wijewickreme
Keyword(s):  
Natural Gas ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Full Scale ◽  
Ground Movement ◽  
Nonlinear Material ◽  
Soil Movement ◽  
Pipeline Systems ◽  
Ground Displacements

The performance of buried natural gas pipeline systems in areas subjected to permanent ground displacements is an important engineering consideration since geotechnical hazards can be a major cause of damage to these utilities. Although pipe-soil interaction models exist, there is only limited experience with pipeline materials other than steel, and particularly in relation to polyethylene (PE). With this background, a detailed research program involving full-scale physical model testing of buried pipeline systems was undertaken, and performance of straight PE pipes subject to relative axial soil movement was investigated as a part of this work. A closed-form solution was derived to account the nonlinear material response of MDPE pipes subject to relative axial soil movement, and the analytical results are compared with the results obtained from the full-scale testing. This closed-form solution provides a rational framework to estimate the response of the pipe (level of strain, force) and even the mobilized frictional length along the pipe for a known amount of ground displacement. The approach, in turn, could be used in estimating the relative axial soil displacement needed for pipe failure, which is an important consideration in the evaluation of the field performance of MDPE pipe systems located in areas of potential ground movement.

Scale Model Investigations on Vibro Pile Driving

2018 ◽  
Author(s):  
Philipp Stein ◽  
Nils Hinzmann ◽  
Jörg Gattermann
Keyword(s):  
Penetration Depth ◽  
Earth Pressure ◽  
Offshore Wind ◽  
Scale Model ◽  
Pile Driving ◽  
Scaled Model ◽  
Dense Sand ◽  
Pressure Transducers ◽  
Vibration Technique ◽  
Force Equilibrium

Monopiles installed by impact driving are the preferred system for the foundation of offshore wind turbines in water depths up to 40 m. The vibration technique as alternative installation method has big advantages regarding piling noise and installation time. Much experience exists for the design and installation of impact driven piles. Within the research project ZykLaMP, the lack of experience concerning vibrated monopiles shall be faced by means of large-scaled model investigations regarding the lateral load-bearing behavior. Therefore, open ended steel pipe piles (L = 2.4 m, Dpile = 0.6 m) are installed into dense sand by means of impact and vibratory pile driving and then subjected to cyclic lateral loading. This paper focusses on pile driving predictions and measurements during the installation process. Pile driving post-predictions were carried out based on a simple force equilibrium approach. Model piles were installed using two different vibro hammers with different eccentric moments and one impact hammer. Measurements of strains and accelerations were carried out to investigate dynamic movements during pile driving. Earth pressure transducers were used to investigate the development of soil stresses due to the installation process. Measurements show that even at high acceleration amplitudes a refusal to vibratory driving may occur at a certain penetration depth. Soil stresses in the vicinity of the pile decrease to about 50 % due to vibratory driving which is one reason for the friction fatigue phenomenon. Drivability studies using the force equilibrium model give rough predictions about whether or not a pile can be driven to a certain penetration depth but are quite sensitive to input parameters. For the model tests, post-predictions gave reasonable results.

The Research on the Steel Asphalt Isolation Pier by a Full-Scale Masonry Model

2011 ◽  
Vol 94-96 ◽  
pp. 1054-1059
Author(s):  
Shou Ping Shang ◽  
Huang Quntang
Keyword(s):  
Base Isolation ◽  
Single Layer ◽  
Seismic Energy ◽  
Sine Wave ◽  
Full Scale ◽  
Scale Model ◽  
Rural Buildings ◽  
Acceleration Amplitude ◽  
Research Findings ◽  
Volume Production

In view of the universal present situation where general rural buildings has low earthquake resistance ability, this paper, based on the base Isolation theory and the steel-asphalt isolation layer, proposes the steel-asphalt isolation pier to overcome the shortcomings of relatively complex construction and inconvenient volume production. The present study has also carried full-scale model experiment on the houses of single-layer full-scale masonry structure. The result shows that with the sine wave input of different acceleration amplitude, the superstructure acceleration weakens more than 40% and gets good damping effect because a majority of seismic energy has been absorbed by the isolation pier; and when the acceleration amplitude is below 0.30 grams, the steel of isolation pier is to be at the elastic state and can reset automatically after shock, which can satisfy the requirements of the seismic design. However, in order to meet the demand of the topic research, the present study has only done experiment on the small earthquake. According to the research findings, the attenuation coefficient , on the whole, tend to increase with the increase of acceleration peak value.

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