variety of methods including traditional factor of safety approaches, including BS (BSI, ) and (BSI, ), CIRIA C (Phear et al, ) . Publisher: CIRIA. Soil nailing is a technique where either natural ground or fill material is reinforced by the insertion of slender tension-carrying elements called . thread Hi, My dissertation is within the scope of nailing in soils. I would like to consult the book mentioned in the topic title with the.
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Skip to main content. Log In Sign Up. Experimental and theoretical study on pullout resistance of grouted soil nails.
In Hong Kong, grouted c6637 nails have been used in most slope stabilization works since the late s. Soil nail pullout resistance is a key parameter in the design of soil nailing.
The design of a soil nailed system for slope stabilization will be improved, if the pullout resistance can be more accurately estimated. Nowadays, researchers and engineers have acknowledged that many factors influence the pullout resistance of soil nails, such factors include installation method, overburden pressure, grouting pressure for grouted nailsroughness of nail surface, degree of saturation of the soil, soil dilation, bending of the soil nail.
This research has therefore commenced to study the pullout resistance of grouted soil nails. Firstly a simple mathematical model for the interaction analysis of a soil nail and the surrounding soil has been developed. This model takes curia account some key factors, which are constrained soil dilation, soil nail bending, vertical pressure, and non-linear subgrade reaction stiffness. The lateral subgrade reaction between the soil and the soil nail is assumed to obey a hyperbolic relation.
Reported test data in the literature are used to verify the present model. Good agreement is found from the comparisons in two case studies. The analyses show that the contribution of the soil nail bending to the pullout resistance is of secondary importance as the tension failure is dominant in a soil-nailed slope.
Secondly, a series of laboratory c37 nail pullout tests have been c6637 out to study the influences of both grouting pressure and firia pressure on the soil nail pullout interface shear resistance. The pullout tests were ckria in a completely decomposed granite CDG soil c63 a saturated condition.
The test procedures simulated the real construction process of a soil nail, including the establishment of initial soil stress, drilling a hole with stress release, pressure grouting, soil saturation, and soil nail pullout. The pullout box was well instrumented. Typical test results are presented and discussed. From the data analysis, the effects of both grouting pressure and overburden pressure on the soil nail pullout resistance are investigated.
It is found that both overburden pressure and grouting pressure have influences on soil nail pullout resistance, and their influences are interactional.
Soil Nailing: C637: Best Practice Guidance
The soil nail pullout resistance is hardly or slightly dependent on the overburden pressure when the grouting pressure is low, but increases with the overburden pressure when the grouting pressure is higher. Based on the test results, a new empirical liner equation is proposed for the determination of soil nail pullout resistance considering both grouting pressure and overburden pressure.
Finally, a three-dimensional 3D ciriia element model has been established for modelling the laboratory soil nail pullout tests carried out in The Hong Kong Polytechnic University.
The model simulates all the procedures of the pullout tests for the cases of both c6637 soil without pressure grouting and saturated soil with pressure grouting. The model is verified by the comparisons between the results from the numerical modelling and the pullout test data.
The FE modelling shows that the stress distribution in the soil nail axial direction is non-uniform at large pullout displacement in the unsaturated soil condition, but basically uniform in the saturated condition. It was his supports and experienced guidance that made this work possible.
The privilege of working with Professor Yin has appreciably influenced my professional development and perspectives. I would like to express my thanks to Mr. Finally, I would like to express my sincere thanks to my dear parents, teachers, and friends whose encouragement, friendship and love over the last three years have enabled me to reach a new level in my life.
Hong Kong has a substantial portion of urban developments located on or near steep hillsides, resulting in the creation of 57, sizable man-made slopes. Coupled with an annual rainfall of mm on average, the slope safety problem is serious in Hong Kong.
PUB C Soil nailing – best practice guidance, CIRIA – Publication Index | NBS
These slopes are liable to failure in periods of intense tropical rainfall, resulting in severe loss of life and property damage. Inthe year Extended LPM Project commenced to upgrade substandard government man-made slopes and undertake safety screening studies for private man-made slopes each year up to The soil nailing technique was introduced to Hong Kong in the s.
Introduction advantages of simplicity, speed construction, and economical efficiency, soil nailing has been increasingly used and become the most common slope stabilization method in Hong Kong. More than slopes and retaining walls are upgraded cciria grouted soil nails each year GEO Although the design guidelines are available in many countries, some design issues remain ambiguous among some engineers and researchers.
Many of the issues under debate are related to the determination of soil nail pullout resistance, cieia is a key parameter in the soil nail design.
Soil nailing – best practice guidance (C637)
Cirua design can be achieved, if the pullout resistance is more accurately predicted. Many researchers and engineers have found this parameter is influenced by many factors.
Such factors include installation method, overburden pressure, grouting pressure, roughness of nail surface, water content of the soil, soil dilation, and soil nail bending. The following specific issues are to be studied: This chapter presents briefly the background, the objectives and specific issues to be investigated, and ciriia organization of the thesis. The review finds out the development and application history of soil nailing and research findings on the soil nail pullout resistance.
Introduction current design methods of grouted ckria nails are presented and discussed. The influencing factors of soil nail pullout resistance are summarized. Research work on the behaviour and mechanisms of soil nails by means of field monitoring, laboratory testing and numerical modeling are reviewed. A simple mathematical model for the determination of soil nail pullout resistance. A simple mathematical model for the interaction analysis of a soil nail and the surrounding soil has been developed.
The model takes into account a few key parameters, which are soil dilation, soil nail bending, vertical pressure, and non-linear subgrade reaction stiffness of the soil. Reported test data in the literature were used for model verification.
The relative contribution of the soil nail bending on the soil nail pullout resistance in a large-scale soil nailed wall and in direct shear tests are discussed. Test setup, materials and procedures. Laboratory tests have been carried out to study the influences of overburden pressure and grouting pressure on the soil nail pullout resistance in a saturated CDG soil. The test setup, materials properties, and test procedures of the laboratory pullout tests are presented in this chapter.
Laboratory soil nail pullout experiments and results. The test programme is introduced and the data obtained throughout the tests are presented in this chapter. The stresses and pore water pressures developed in the soil, the pullout force and displacement of the soil nail, and the strains developed along the soil nail are plotted for each phase of ckria experiment.
Effects of both overburden pressure and grouting pressure. The pullout test data are further analyzed, compared and interpreted in this chapter. The effects of both overburden pressure and grouting pressure on the soil nail pullout resistance are evaluated and discussed.
A new cirix linear equation for determination of soil nail pullout resistance is proposed. A 3D finite element model for simulating soil nail pullout tests. A three-dimensional 3D finite element FE model has been established for simulation of the soil nail pullout tests in this chapter. The model simulates all the procedures of the pullout tests for the conditions of both unsaturated v637, without pressure c6377 and saturated, with pressure grouting. The factors of soil dilation, overburden pressure and grouting pressure are considered in the FE model.
The model mesh, simulation procedures, material constitutive models and parameters are presented and discussed. Model verification and discussion. The verification of cciria 3D finite element model with the laboratory pullout test data is presented in this chapter. The effects of soil dilation, overburden pressure, and grouting pressure are considered in simulation. The stress variations in the soil and the soil nail pullout behaviour at different test steps and conditions are compared with the experimental data and discussed.
Summary, conclusions and suggestions.
A summary and main conclusions made from this research project are presented. Suggestions are given for further research in the topic area.
Introduction a b Figure 1. This is accomplished by installing closely spaced, passive, structural inclusions, known as nails, into the soils to increase their overall shear strength.
During the s, the soil nailing technique was developed in France, Germany and the United States. Thereafter, the technique has been increasingly used in soil reinforcement projects all over the world.
In Hong Kong, soil nails are extensively used for slope improvement works. Tens of thousands of soil nails have been installed for stabilizing existing substandard existing soil slopes or new man-made slopes each year. The aim of this chapter is to review of the application and development of the soil c67 technique, and research findings regarding soil nail pullout resistance.
The soil nailing technique is first introduced. This includes application and development history, behaviour and mechanisms, and design methods.
The influencing factors of the soil nail pullout resistance are then discussed. Finally, previous research on the behaviour and mechanisms of soil nail systems, by means of field monitoring, laboratory experiments and numerical modelling, are reviewed.
Literature Review is a poor structural material because it is weak in tension. In contrast, steel is strong in tension. Soil nails are divided into several types, based on the installation methods used. They include such as driven nails, grouted nails, and jet-grouted nails. A brief description of the three types of soil nails is given below. Driven nails are composed of ordinary steel bars or angle bars, driven into the ground at the designed inclination by the ballistic method using a compressed air launcher, by the percussive method using hammering equipment, or by the vibratory method using a vibrator.
The nail diameter is normally mm. The steel properties should be perfectly ductile rather than brittle Myles,to avoid a brittle failure. This installation technique is rapid 4 to 6 per hour and causes little ground disruption.
However, it is limited by the length of the bars maximum length about 20m firia by the heterogeneity of the ground e. Grouted d637 typically consist of a steel ciriaa with a diameter 15 – 46mm, with mm thick grout cover. The steel bar is placed in pre-drilled hole mm in diameter with a vertical and horizontal spacing, typically varying from 1 to 3m, depending on the type of in-situ soil.