Analytical and model studies of reinforcement of a layer of granular fill on a soft clay subgrade

1987 ◽  
Vol 24 (4) ◽  
pp. 611-622 ◽  
Author(s):  
J. P. Love ◽  
H. J. Burd ◽  
G. W. E. Milligan ◽  
G. T. Houlsby
Keyword(s):  
Soft Clay ◽  
Model Tests ◽  
Reinforced Soil ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Membrane Action ◽  
Geogrid Reinforcement ◽  
Granular Fill ◽  
Soft Clay Subgrade

The effectiveness of geogrid reinforcement, placed at the base of a layer of granular fill on the surface of soft clay, has been studied by small-scale model tests in the laboratory. In the tests, monotonic loading was applied by a rigid footing, under plane strain conditions, to the surface of reinforced and unreinforced systems, using a range of fill thicknesses and subgrade strengths. Continuous measurements were made of footing load and footing displacement, and deformations of the subgrade and of the geogrid reinforcement were measured from photographs. From these measurements the different mechanisms of failure in the unreinforced and reinforced system were established. Performance of reinforced systems was found to be superior even at small deformations, owing to the significant change in the pattern of shear forces acting on the surface of the clay, brought about by the presence of the reinforcement. Membrane action of the reinforcement only became significant at large deformations.A finite element computer program has been specially formulated to allow inclusion of a thin reinforcing layer, and to handle correctly the large deformations and strains induced in the physical models. This formulation is able to reproduce satisfactorily the main features of behaviour observed in the models, and may now be used with some confidence to perform accurate predictions for full-scale structures. Key words: bearing capacity, clays, finite elements, foundations, geotextile, granular materials, model tests, reinforced soil, roads.

scholarly journals CEOHYDRAULIC INVESTIGATIONS OF RUBBLE MOUND BREAKWATERS

1988 ◽  
Vol 1 (21) ◽  
pp. 166 ◽  
Author(s):  
W. Burger ◽  
H. Oumeraci ◽  
H.W. Partenscky
Keyword(s):  
Pore Pressure ◽  
Scale Effects ◽  
Numerical Models ◽  
Model Tests ◽  
Physical Models ◽  
Core Material ◽  
Scale Model ◽  
Small Scale ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Due to the increase of ship sizes in recent decades a number of harbours and terminals have been built in deeper waters. Accordingly, the structures which have to provide protection against wave action become higher, too. In most cases, these protective structures are of the rubble mound type. Under such conditions the flow induced by waves within the breakwater and the related geotechnical behaviour of the rubble mound fill become more significant fcr the overall stability and should be considered in the design. In addition, it is known that the scales usually adopted in hydraulic models (1:30 to 1:60) for investigating the stability of large rubble mound breakwaters generally lead to scale effects with respect to the flow field inside the breakwater. This means that small-scale model tests are not appropriate for investigating the internal flow patterns or for evaluating the pore pressure field induced by the incident waves in,the core material. because of the uncontrolled conditions in the prototype, and since the actual permeability of the prototype rubble mound fill cannot be predicted (segregation, settlement, variation in grading, etc.), the use of large-scale physical models seems to be the most promising method for basic investigations of this kind. Moreover, the results of such largescale model tests may be used to validate the usual smaller scale models and to calibrate numerical models. Therefore, it is one of the objectives of our research programme on rubble mound breakwaters, which started in 1987, to concentrate on the evaluation of the wave-induced flow and pore pressure distribution within the breakwater.

THE CONSOLIDATION OF SOFT CLAY FOUNDATION GROUND USING GEOSYNTHETICS COMBINED WITH THE ELECTRO-OSMOSIS PROCESS

2020 ◽  
Author(s):  
Florin Sebastian Mustăţea ◽  
Raluca Ioana Nicolae
Keyword(s):  
Soft Clay ◽  
Electrical Current ◽  
Physical Models ◽  
Scale Model ◽  
Consolidation Process ◽  
Soft Clays ◽  
Electro Osmosis ◽  
Speed Up ◽  
Drainage Capacity ◽  
Soft Clay Subgrade

In the last decade, the construction of communication routes has intensified in Romania. As a result, many case studies related to the presence of saturated clayey soils in the foundation ground have emerged. In order to speed up the execution of highways and railways in a safely manner, the designers use different methods of improving soft clays in terms of compressibility. The present study aims to evaluate the efficiency of an electrical current used for the vertical dewatering of a soft clay subgrade, through simple physical models. The experimental study is being performed on a laboratory scale model by using electrodes and geosynthetics for drainage, along with the vacuum technique. The vertical drainage capacity during the electro-osmotic dewatering process, combined with preloading, drainage, vacuum and heat induction is being evaluated. The integrated effect of these methods on the consolidation process will be analyzed for the final conclusions.

scholarly journals Ground improvement using granular pile anchor system: resistance to heave and uplift pressure

2020 ◽  
Vol 19 (1) ◽  
pp. 403
Author(s):  
Alvin John Lim Meng Siang ◽  
Ehab Hamad Sfoog ◽  
Nahla Naji ◽  
Sim Sy Yi ◽  
Nickholas Anting Anak Guntor ◽  
...  
Keyword(s):  
Moisture Absorption ◽  
Expansive Soils ◽  
Ground Improvement ◽  
Reinforced Soil ◽  
Scale Model ◽  
Small Scale ◽  
Numerical Investigations ◽  
Anchor System ◽  
Pull Out ◽  
Granular Pile

<span lang="EN-GB">Expansive soil is found in many parts of the world where its major drawback is its expansion and shrinking property upon moisture absorption and drying during alternation of rainy-dry seasons. Due to its swelling-shrinkage repeated process, fatigue and distress cause crack to structures. Granular pile anchor (GPA) system is a pioneering technique that is utilised in reinforcing these expansive soils. Granular pile anchor (GPA) system is a pioneering technique that is utilised in reinforcing expansive soils. The GPA provides tensile resistance which arrest the exerted upward forces and hence reducing heave. Previous investigations have only focused on load-displacement relationships by utilizing the pull-out technique. In this technique, an external force pulls the GPA and the corresponding displacements are recorded. The results provide indication of the GPA resistance to the applied force. However, in real conditions the heave and expansion forces were developed as a result of the pressure caused by the water absorption which pushes the entire soil bed in the upward direction along with the GPA. Therefore, this paper is aimed to explore this concept by carrying experimental and numerical investigations on a small scale model for a single pile with a diameter of 4 cm, with lengths of 20 and 40 cm. Ultimately, the reinforced soil exhibits reduction in upward force and heave compared to the unreinforced soil. Also, verifications for the testing shows that the relationship between the upward force and heave exhibits almost linear relationship for both experimental and numerical investigations. Therefore, shallow foundations incorporated with a GPA system proves to effectively lessen the heave that occurs in expansive soils which in turn can solve problems for constructions.</span>

Small‐Scale Model Tests of Structural Steel Assemblies

1989 ◽  
Vol 115 (8) ◽  
pp. 1999-2015 ◽  
Author(s):  
Benjamin J. Wallace ◽  
Helmut Krawinkler
Keyword(s):  
Structural Steel ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Small Scale Model

Evaluation of a Small and Fast Planing Boat’s Seakeeping Performance at the Design Stage

2015 ◽  
Author(s):  
Dong Jin Kim ◽  
Sun Young Kim
Keyword(s):  
Model Tests ◽  
Full Scale ◽  
Scale Model ◽  
Design Stage ◽  
Small Scale ◽  
Irregular Wave ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Scale Ratio ◽  
Free Running

Seakeeping performance of a planing boat should be sufficiently considered and evaluated at the design stage for its safe running in rough seas. Model tests in seakeeping model basins are often performed to predict the performance of full-scale planing boats. But, there are many limitations of tank size and wave maker capacity, in particular, for fast small planing boats due to small scale ratio and high Froude numbers of their scale models. In this research, scale model tests are tried in various test conditions, and results are summarized and analyzed to predict a 3 ton-class fast small planing boats designed. In a long and narrow tank, towing tests for a bare hull model are performed with regular head waves and long crested irregular head waves. Motion RAOs are derived from irregular wave tests, and they are in good agreements with RAOs in regular waves. Next, model ships with one water-jet propulsion system are built, and free running model tests are performed in ocean basins. Wave conditions such as significant heights, modal periods, and directions are varied for the free running tests. Motion RMS values, and RAOs are obtained through statistical approaches. They are compared with the results in captive tests for the bare hull model, and are used to predict the full-scale boat performances.

scholarly journals Pile Model Tests Using Strain Gauge Technology

2015 ◽  
Vol 37 (3) ◽  
pp. 49-52 ◽  
Author(s):  
Adam Krasiński ◽  
Tomasz Kusio
Keyword(s):  
Bearing Capacity ◽  
Axial Force ◽  
Strain Gauge ◽  
Force Measurement ◽  
Ground Level ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Pile Head ◽  
Pile Model

Abstract Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

scholarly journals Measurement of three-dimensional displacement field in piled embankments using synchrotron X-ray tomography

2019 ◽  
Vol 56 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Louis King ◽  
Abdelmalek Bouazza ◽  
Anton Maksimenko ◽  
Will P. Gates ◽  
Stephen Dubsky
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Full Field ◽  
X Ray ◽  
Wide Range ◽  
Piled Embankments

The measurement of displacement fields by nondestructive imaging techniques opens up the potential to study the pre-failure mechanisms of a wide range of geotechnical problems within physical models. With the advancement of imaging technologies, it has become possible to achieve high-resolution three-dimensional computed tomography volumes of relatively large samples, which may have previously resulted in excessively long scan times or significant imaging artefacts. Imaging of small-scale model piled embankments (142 mm diameter) comprising sand was undertaken using the imaging and medical beamline at the Australian Synchrotron. The monochromatic X-ray beam produced high-resolution reconstructed volumes with a fine texture due to the size and mineralogy of the sand grains as well as the phase contrast enhancement achieved by the monochromatic X-ray beam. The reconstructed volumes were well suited to the application of digital volume correlation, which utilizes cross-correlation techniques to estimate three-dimensional full-field displacement vectors. The output provides insight into the strain localizations that develop within piled embankments and an example of how advanced imaging techniques can be utilized to study the kinematics of physical models.

Controlling sand placement during the building of artificial islands

1984 ◽  
Vol 21 (2) ◽  
pp. 371-375 ◽  
Author(s):  
D. H. Shields ◽  
L. Domaschuk ◽  
D. W. Corkal ◽  
J. R. McCutchon
Keyword(s):  
Cost Saving ◽  
Low Cost ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Considerable Cost ◽  
Environmentally Safe ◽  
Considerable Cost Saving ◽  
Small Scale Model

A new way to construct artificial islands of sand is described. The method shows promise of considerable cost saving. The present high cost of island building is due to the difficulty of making underwater sand slopes steep. Simply dumping sand into the ocean results in slopes of from 12 to 15 horizontal to 1 vertical. These shallow slopes have enormous implications in terms of sand volume and cost. The sand can be tremied into place to form a steep-sided ring or bund. Handling large quantities of sand in this way is expensive. Small-scale model tests show that if the sand is mixed with certain chemicals the resulting 'cohesion' enables the sand to fall through seawater as a block, with little dispersion. Steep underwater slopes result. Low-cost, nontoxic (environmentally safe) chemicals were used in the experiment. Keywords: construction, artificial islands, sand, oceans, dredging.

Pipeline plough performance in sand waves. Part 1: model testing

2010 ◽  
Vol 47 (1) ◽  
pp. 49-64 ◽  
Author(s):  
Mark Fraser Bransby ◽  
Michael Brown ◽  
Andrew Hatherley ◽  
Keith Lauder
Keyword(s):  
Model Testing ◽  
Model Tests ◽  
Scale Model ◽  
Soil Conditions ◽  
Small Scale ◽  
Offshore Pipelines ◽  
Sand Waves ◽  
Increased Risk ◽  
Small Scale Model ◽  
Spoil Heaps

Offshore pipelines are often buried in the seabed by ploughing a trench, placing the pipe at the base, and then backfilling. The ploughing operation is critical in terms of cost and project time, with increased risk due to uncertain soil conditions or geohazards. One problem that can be encountered is the presence of sand waves or megaripples on the seabed surface. This may affect the progress of the plough, prevent the plough from generating a level trench or modify the size of the spoil heaps for backfilling. These aspects have been investigated by conducting a series of small-scale model tests in the laboratory. These have revealed information about the plough kinematics and the resulting trench conditions when ploughing in sand waves with different wavelengths and amplitudes. It is shown that it may be possible to plough through regions of sand waves and estimate likely plough performance by knowing the sand wavelength and amplitude relative to the plough size.

Wave overtopping and splash-up at seawalls with bullnose

2020 ◽  
Vol 20 (3) ◽  
pp. 333-342
Author(s):  
Le Hai Trung ◽  
Dang Thi Linh ◽  
Tang Xuan Tho ◽  
Nguyen Truong Duy ◽  
Tran Thanh Tung
Keyword(s):  
Storm Surges ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Wave Overtopping ◽  
Run Up ◽  
Coast Of Vietnam ◽  
Small Scale Model ◽  
Wall Interactions

Seawalls have been erected to protect hundreds of towns and tourism areas stretching along the coast of Vietnam. During storm surges or high tides, wave overtopping and splash-up would often threaten the safety of infrastructures, traffic and residents on the narrow land behind. Therefore, this study investigates these wave-wall interactions via hydraulic small scale model tests at Thuyloi University. Remarkably, the structure models were shaped to have different seaward faces and bullnoses. The wave overtopping discharge and splash run-up height at seawalls with bullnose are significantly smaller than those without bullnose. Furthermore, the magnitude of these decreasing effects is quantitatively estimated.

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