Reinforced soil engineering advances in research and practice pdf
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- Recent advances in geosynthetic-reinforced retaining walls for highway applications
- Reinforced Soil Structures Volume I. Design and Construction Guidelines
Newell, Darren, and Erwin Oh. The use of fiber reinforced polymer FRP materials in civil engineering structures is relatively new. FRP reinforcing bars are starting to be used in lieu of conventional steel reinforcing bars where improved corrosion resistance is required in soil nailed reinforced earth retaining structures.
Recent advances in geosynthetic-reinforced retaining walls for highway applications
Assessment of Slope Stability. Reston: ASCE, , pp. ISBN Assessing the stability of slopes is a difficult task that requires a rigorous approach. This paper starts by presenting a geotechnical characterization of slope movements that helps in classifying the information related to slopes.
A methodology for assessing the stability of slopes is presented. It includes qualitative and quantitative approaches and, separately, the characterization of the post-failure stage. Finally, there is some discussion on the use of factor of safety, use of numerical models and consideration of risk. Business of Geotechnical and Geoenvironmental Engineering. This paper presents the author's perspectives on the state of the industry with respect to U. The paper discusses: the history and evolution of the business sector; size and attributes of the sector; business models and practice characteristics of companies in the sector; and operational, management, and personnel priorities and challenges of these firms.
The paper also addresses career considerations for personnel in this business sector, and the topics of clients and competition, risk management and contractual liability, mergers and acquisitions, and the author's thoughts on future directions for the business sector over the next 10 to 20 years. Sustained business success is being achieved by both large and small firms practicing geoengineering that can recruit and retain great people, provide superior work deliverables and solutions to their clients, perform their work efficiently and at a reasonable cost, and navigate both the competitive and risk management landscapes.
A significant and exciting challenge for the senior management teams of these firms now and in the future is to achieve and integrate excellence in technical practice development, project management performance, personnel development and retention, risk and quality management, financial performance, and equity and ownership management to continually improve their firms and, in so doing, improve the profession.
Physical Modelling in Geotechnics. A circulating system has been developed to control water levels and circulate water in centrifuge models. A vortex pump was installed under water to supply stable upstream discharge. A steel model box was designed to protect the pump against possible damage during tests.
A method to guarantee a stable outlet flow was developed. A series of tests were carried out to confirm the stability of the equipment.
It has been shown that the system can supply stable discharge subjected to centrifugal accelerations up to 30 g. The relation between water elevation in triangular weir container and centrifugal acceleration has been proposed. A brief introduction to centrifugal tests on breaching process of earth embankments has been given.
The system was developed to answer the increasing need for highly complex motion and load sequences to be applied during centrifuge model tests. It features four PID controllers, each driving an independent axis of actuator motion or controlling another tool , a waveform generator and sequence controller. These modules are contained within a single intuitive user interface. All of the researchers and technicians involved in experiments using the UWA beam centrifuge are capable of operating this system, after brief training by the beam centrifuge operator, supported by the software author.
During the modeling of a railway subgrade to ensure that the conditions are close to those of the prototype, it is necessary to apply a load to the model, which corresponds to that of passing trains. Trains cause vibratory and dynamic influences on subgrade soils. Professor T. Yakovleva and engineer D. The loading device is a closed system of electromagnetic power vibrators, which creates the required influence on the embankment model.
Power interactions between a ferromagnetic body and an external agnetic field are used in the vibrators. A magnetized spool perceives control signals and applies the necessary magnetic field. A working magnetic flow is created by the windings, pulse current is passed through the windings and the current is controlled by the power of the electromagnetic attraction.
A crosshole tomography testing system using bender elements has been developed to measure shear wave velocity distribution in centrifuge models. Sixteen series type bender elements for shear wave transmitters and sixteen parallel type bender elements for receivers are used for the testing system.
A series of testing has been conducted in uniform sand sample and tomography inversion considering curved ray path has been conducted. The shear wave velocity variation with depth has been verified by comparing with resonant column test result. This system has also been used for measuring shear wave velocity distribution in model soil with surface loading condition and the change of shear wave velocity beneath the loading area could be monitored during loading stage.
From this result, the changes of shear wave velocity and vertical effective stress could be estimated and the feasibility of developed testing system to general centrifuge model tests could be confirmed. Four samples of dry sand were prepared at different densities, in which a small scale model of circular tunnel was inserted, instrumented with gauges measuring hoop and bending strains. Arrays of accelerometers in the soil and on the box allowed the amplification of ground motion to be evaluated; LVDTs measured the soil surface settlement.
This paper describes the main results of this research, showing among others the evolution of the internal forces during the model earthquakes at significant locations along the tunnel lining. Dynamic centrifuge model tests, conducted to investigate response earth pressure and deformation of sewer pipes buried in sloping-sided ditches, quantified effects of investigated factors, such as ditch wall inclination, cover height, backfill soil type and pipe flexibility, on the pipe response.
Comparison between static and dynamic centrifuge model tests revealed that the safety of the pipe was more critical under vehicle loading applied in the static tests rather than under seismic loading applied in the dynamic tests. We investigate the face failure mechanism for shallow circular tunnels that are excavated in a dry, cohesionless soil by means of a physical model and analyse the experimental results by means of limit equilibrium calculations.
The physical model consists of a sand box with a tunnel, which was modelled by a clear acrylic half pipe. The tunnel face support was modelled in two ways: as a rigid movable face with a PVC plate; and as a flexible face with a pressurised air bag. A series of tests were performed with an overburden of one, two and three times the tunnel diameter.
The kinematics of the failure body were determined, as well as the required support pressure. The test results agree well with the predictions of the analytical model.
This paper describes the results of laboratory model tests on small diameter pipes buried in reinforced trench under repeated loads. Radial deformation of the tested pipes and consequently the value of Vertical Diametric Strain VDS of the pipe were recorded. The results show that the value of VDS increases rapidly during a few first loading cycles while the rate of deformation, significantly, reduces as the number of cycles increase.
The parameters varied in the testing program include relative density of the sand, number of reinforced layers and cover on pipe. The value of VDS was significantly reduced with increased the pipe embedment depth, soil relative density and number of layers of reinforcement. The performance of reinforced soil decreases with an increase in the number of reinforced layers.
In addition, the improvements in the values of Vertical Diametric Strain VDS decreases with increase the soil density and embedded depth of pipe. An exploratory laboratory study using the miniature 2-axis MEMS Micro-Electro-Mechanical System accelerometers and a 3-axis wireless accelerometer to identify landslip characteristics in both sudden and gradual slope failure was carried out in this paper.
These miniature sensors in the test were buried into different positions of the slope constructed in the laboratory flume and followed the landslide to move.
The recorded sensor responses demonstrate that these sensors can capture the features of landslide motion, for instance, minor multiple events of surface sliding or a major flow landslide; initiation and stop of a landslip; and the direction of the soil movement in slope failure. The success of the application of these sensors on monitoring how a landslide moves suggests that these MEMS sensors have the potential to be used in the field to improve the monitoring system for natural and man-made slopes, which proves to be vital from a socioeconomic perspective.
Measurement of acceleration in dynamic tests is carried out routinely, and in most cases, piezoelectric accelerometers are used at present. However, a new class of instruments based on MEMS technology have become available and are gaining use in many applications due to their small size, low mass and low-cost. This paper describes a centrifuge lateral spreading experiment in which MEMS and piezoelectric accelerometers were placed at similar depths.
Good agreement was obtained when the instruments were located in dense sands, but significant differences were observed in loose, liquefiable soils. It was found that the performance of the piezoelectric accelerometer is poor at low frequency, and that the relative phase difference between the piezoelectric and MEMS accelerometer varies significantly at low frequency.
This paper studies the effect of saturation of backfill on the seismic stability of Reinforced Soil Walls RSWs using centrifuge shaking table tests. For comparison, degradation of static stability and seismic stability of a RSW under unsaturated condition was also investigated.
Test results showed that the RSW under saturated condition had enough static stability, but seismic stability significantly decreased compared with that under unsaturated conditions. However, the model RSW did not collapse, though large deformations developed, having maintained sufficient stability after shaking despite the appearance of a clear slip surface in the backfill.
Finally, evaluation of the residual stability of RSWs damaged in earthquakes is discussed, with test results presented with a simple evaluation method proposed by authors. Drill rigs are large pieces of construction machinery. This machinery is used for ground improvement and foundation work. In recent years, there have been reports of accidents in which the machinery toppled over. The load on each axle and the behaviour of the model were measured in a centrifuge test.
The ground used with the model consisted of two kinds of materials, with conditions modeling uniform ground and non-uniform ground. This study also proposes safety requirements on the bearing capacity of ground to maintain the stability of drill rigs.
Performance evaluation of buried extensible pipes subject to ground deformation is a key consideration for utility owners. Unlike in steel pipes, the smaller deformation stiffness and nonlinear stress—strain response of plastic pipes give rise to complex pipe-soil interaction mechanisms. Several pipe pullout tests were performed using a full-scale pullout chamber of size 3. In each test, pullout resistance, axial strain and displacement at selected pipe locations were measured. A numerical model was developed to assess the performance of pipes, incorporating the changes in normal soil stress on the pipe from soil dilation around the pipe and frictional degradation at large displacements.
Pipe was modeled considering the viscoelastic stress-strain behavior. The results from numerical approach are in good agreement with data obtained from pullout tests, demonstrating the importance of accounting for the above aspects in extensible pipes. In a series of plane strain model pile tests both the stresses and strains in the soil material near a penetrating pile are quantified.
The stresses are measured with an improved photoelastic measurement method, whereas the strains are calculated from the displacement fields resulting from digital image correlation.
The photoelastic method requires that the soil is substituted with a birefringent material. In this research broken glass in a refractive index matching oil is used. The stress in the field correlates well with the measured boundary loads. The strains show an apparent loosening below the base and a densification in the side lobes. A guide to field instrumentation in geotechnics: principles, installation and reading Richard Bassett.
Geotechnical instrumentation is used for installation, monitoring and assessment on any sizeable project, particularly in urban areas, and is used for recording, controlled remedial work, and safety. This unique and up-to-date book deals with the conceptual philosophy behind the use of instruments, and then systematically covers their practical use.
It is divided into displacement dominated systems and stress recording systems. The limitations are discussed and the theoretical background for data assessment and presentation are covered in some detail, with some relevant background material in theoretical soil mechanics.
Relevant advanced electronic techniques such as laser scanning in surveying and fibre-optics are also included and communication and data recovery systems are discussed. This book is written for senior designers, consulting engineers, and major contractors who need a major introduction to the general purpose, availability, and analysis of field instruments before details of their own project can be progressed, and it serves as a textbook to any specialist geotechnical MSc or professional seminar course in which instrumentation forms a major part.
Reinforced Soil Structures Volume I. Design and Construction Guidelines
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. An important objective of this study is to unequivocally define the boundaries for such behavior. The focus of this review was to summarize pertinent information published in technical venues that was deemed relevant to assess 1 the different components of the research and 2 the composite behavior of GRS structures. While the most common geosynthetic type is geogrids, the majority of US structures were constructed using woven geotextiles.
The accumulation of waste tires is a global resource and environmental problem. The landfill or incineration of tires will infiltrate toxic chemicals into the surrounding environment, which poses a serious ecological threat to the environment. A large number of studies have shown that waste tires can be used in geotechnical engineering, which provides a good idea for the recycling of waste tires. Up to now, researchers have tested the performance of soil mixed with waste tires by dynamic triaxial test, California load ratio test, unconfined compression test, direct shear test, consolidation test, and expansive force test. Rubber can improve the mechanical properties and deformation properties of sand. However, it remains to be seen whether it is sustainable and durable to use waste tire rubber to improve soil properties and whether the chemical composition of waste tire rubber will have adverse effects on soil.
This one-of-a-kind reference evaluates the efficacy, stability, and strength of various soil walls, slopes, and structures enhanced by geosynthetic.
Geosynthetic-reinforced retaining GRR walls have been increasingly used to support roadways and bridge abutments in highway projects. In recent years, advances have been made in construction and design of GRR walls for highway applications. For example, piles have been installed inside GRR walls to support bridge abutments and sound barrier walls.
Assessment of Slope Stability.