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Ground support and shoring
Published in Dudley Robert (‘Rusty’) Morgan, Marc Jolin, Shotcrete, 2022
Dudley Robert (‘Rusty’) Morgan, Marc Jolin
Soil nailing is a construction technique used in certain types of ground to create stable sloped or vertical surfaces. It is usually used in conjunction with reinforced shotcrete to produce a stable temporary or permanent wall able to retain the ground behind it. While the method is referred to as soil nailing, it has been used in a wide variety of ground conditions, ranging from soils to weathered rock and even some types of unweathered rock. The method is an off-shoot of the New Austrian Tunneling Method (NATM) described in Chapter 13 of this book and involves the concept of passive reinforcement of the ground with closely spaced reinforcing steel bars, called nails. Holes are drilled horizontally or sub-horizontally into the ground and the nails, with spacers to centre them in the holes are fully grouted with Portland cement-based grouts. The nails are passive and develop their reinforcing action through nail-ground interactions as the ground deforms during and after construction (FHWA,1998). Figure 12.6 shows a schematic of a soil-nailed wall along with an illustration of a typical grouted soil nail anchor.
Investigation of nailed slope behaviour during excavation by Ng centrifuge physical model tests
Published in Andrew McNamara, Sam Divall, Richard Goodey, Neil Taylor, Sarah Stallebrass, Jignasha Panchal, Physical Modelling in Geotechnics, 2018
A. Akoochakian, M. Moradi, A. Kavand
Due to increase in human needs for construction of building structures and execution of civil projects, deep excavations are necessary where buildings may be constructed in the proximity of slopes or trenches. Collapse and failure of these trenches result in financial damage and loss of life in different parts of the world. Lateral pressure required for occurrence of these failures can develop by the weight of the slope and possible surcharges on the ground nearby the excavation. These surcharges can include soil above horizontal level at excavation edge, nearby buildings, loads due to using nearby roads, etc. In order to prevent failure of unstable trenches, different stabilization methods can be employed. The structures used to stabilize the unstable trench are called retaining structures. Soil nailing operation means stabilization of steep slopes by placing steel bars close to each other called nails in a slope or excavation, during excavation from top to bottom. Nailing is used for passive consolidation (without creating pretension) in the ground and this is done by installing steel bars (nails). Finally, these nails are injected with cement grout to enhance load transfer. By continuation of construction which takes place towards the bottom, a shotcrete layer is also executed on the excavation surface to create continuity between the nails. Nailing technique is commonly used for consolidating slopes and excavations in which the earth removing is done from top to bottom.
Advantages and disadvantages of FBG sensors and strain gauges in the pullout test of GFRP soil nails
Published in Xiaoling Jia, Feng Wu, Electromechanical Control Technology and Transportation, 2017
The soil nailing technique is a technique that uses a great deal of structures (such as steel bar and fiber glass bar), which are closely spaced into the soil in situ to increase the strength of soil slopes and excavations. Obviously, the poor corrosion resistance of the traditional materials has seriously limited its further application. On the contrary, the GFRP soil nail has many advantages over the traditional materials in aspects such as lighter weight, higher strength, and higher electromagnetic resistance, which is significantly lower in relaxation and is more economical. Strain gauges and Fiber Brag Grating (FBG) can be used to monitor the mechanical mechanism of the GFRP soil nail. However, their pros and cons are not defined clearly in previous studies. This report would obtain the advantages and disadvantages of FBG sensors and strain gauges in the pullout test of GFRP soil nails.
Computation of pull-out resistance of pressure-grouted soil nails in sand using cavity expansion and contraction solutions
Published in International Journal of Geotechnical Engineering, 2022
Alpha Lukose, Sudheesh Thiyyakkandi
The soil nailing technique has been widely used for stabilizing existing slopes, roadway embankments, rail-road and highway cut slopes, road widening under existing bridge abutments, etc. Previous studies have shown that the pull-out shear resistance of soil nail, which is a critical design parameter, is influenced by several factors such as method of installation, overburden stress, applied grout pressure, soil dilatancy, roughness of grout-soil interface, degree of saturation, and nail bending (Dey 2015; Lazarte et al. 2015; Hong et al. 2016; Su, Yin, and Zhou 2010; Yin and Zhou 2009). Pressurized grouting of soil nails has been increasingly adopted owing to its advantages over the conventional gravity grouting such as the increased grout zone diameter and the grout-to-soil interface shear resistance (Hong et al. 2013; Kim et al. 2013; Seo et al. 2012; Wang et al. 2017b; Ye et al. 2019a, 2020, 2017; Yin and Zhou 2009; Yin et al. 2009).
Vertical displacement reduction of cohesionless overburden soil by nails in box jacking
Published in International Journal of Geotechnical Engineering, 2020
Kanwar Singh, Satyendra Mittal, Kishor Kumar
Soil nailing is one of the ground improvement methods, which have been widely used for controlling the displacements and protection of natural and man-made slopes (Mittal 2014). A commendable work had been done by many researchers on soil nailing and its applications in the last few decades (Schlosser 1982; Cartier and Gigan 1983; Gassler 1988; Jewell 1989; Jewell and Pedley 1990; Juran et al. 1990; Elias and Juran 1991; Raju 1996; Raju, Wang, and Low 1997; Luo, Tan, and Yong 2000; Patra and Basudhar 2001; Sabhahit, Madhav, and Basudhar 2002; Gupta 2003; Junaideen et al. 2004; Patra and Basudhar 2004; Saran, Mittal, and Gosavi 2005; Gosavi., Saran, and Mittal 2006; Mittal, Singh, and Mathur 2008; Su et al. 2008; Babu and Singh 2010; Rotte, Viswanadham, and Chourasia 2011; Yin, Hong, and Zhou 2012; Mittal. and Shukla 2013; Ghareh 2015; Rawat and Gupta 2016a, 2016b, 2018; Singh et. al., 2018). In the year 2010, authors of this paper had successfully commissioned one project of box push tunnel in New Delhi under a rail track into the cohesionless soil mass which was pre-stabilized by soil nailing technique (Figure 2). During this project, some problems had been encountered in respect of vertical settlements, though all those problems were successfully tackled at the time of execution of project.