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Introduction
Published in Raymond Cheung, Ken Ho, Soil Nailing, 2021
Soil nailing is an in situ ground reinforcement technique that involves the installation of closely spaced slender structural elements, commonly known as soil nails, either by driving, firing, or more commonly the drill-and-grout method. A soil nailed earth structure basically includes the in situ ground to be reinforced, soil nails, nail heads, and/or facing. The technique improves the stability of slopes, retaining walls, embankments, and excavations principally by transferring loads to the ground through the mobilization of tensile forces in the soil nails. The soil nails act to limit the ground deformation near the exposed facing and transfer the stresses to a more stable zone behind the reinforced soil mass. Soil nails are essentially passive elements in which tension is mobilized only if there is ground deformation. The technique evolved in the early 1970s, partly from the techniques for rock bolting and multi-anchorage systems, and partly from the reinforced fill technique. Subsequent technical development work of soil nailing was carried out independently in Europe, the Americas, and Asia from the mid-1970s to the late 2000s. To date, soil nailing has a good performance record and has become one of the common engineering techniques for stabilizing earth structures around the world. In general, the ground conditions most suited for soil nailing include residual soils, weathered rocks with no unfavorable joint orientation, granular soils, and stiff cohesive soils. However, soils that are poorly graded, highly susceptible to frost, with a high organic content, soft clays that are susceptible to creep, and rocks with open joints may not be suitable for soil nailing. In this chapter, salient aspects of the evolution and history of development of the soil nailing technique, its areas of application, the key components, as well as the merits and constraints of the technique are presented. Soil nailing offers an attractive solution to stabilize earth structures from the perspective of its flexibility and cost-effectiveness. Readers should, however, thoroughly understand the merits and constraints of the technique.
Vacuum preloading combined with surcharge preloading method for consolidation of clay-slurry ground: A case study
Published in Marine Georesources & Geotechnology, 2023
Shuangxi Feng, Weiwei Bai, Huayang Lei, Xugen Song, Wei Liu, Xuesong Cheng
The soft ground reinforcement pilot test case is located in the west of Zhuhai city, China. A large amount of infrastructure such as roads, business districts, and administrative buildings has been constructed to create a new ecological new area for tourism, as shown in Figure 1. To expand the land area, the dredger is used to dredge the seabed silt to the continental shelf. The total reclamation area is 11.35 km2. The reclamation thickness is 30 m. Different ground treatment methods such as surcharge preloading, conventional vacuum preloading, vacuum preloading combined with surcharge preloading, and pile composite ground treatment have been adopted on the construction site based on the design requirements of ground construction and the difference in hydraulic fill thickness. This paper focuses on the comparative analysis of the soft ground reinforcement effects of conventional vacuum preloading in pilot test Site I, named Xingfu Road, and vacuum preloading combined with surcharge preloading method in pilot test Site II named Shuanghu Road. The reinforcement length and width of Site I are approximately 1.65 km and 120 m. By contrast, The reinforcement length and width of Site II are roughly 2.56 km and 130 m.
Numerical study on optimisation of cable length and cable location for roadway support by using of improved SA algorithm
Published in European Journal of Environmental and Civil Engineering, 2023
Min Wang, Zhenxing Lu, Wen Wan, Yanlin Zhao
With the development of economy, the requirement of coal is increasing, how to guarantee the stability of the roadway is critically important for coal mining. To ensure the stability of the roadway, different kinds of roadway support and reinforcement technology appeared, such as: steel mesh, shortcrete and U-shape steel, steel and anchor cables. Anchor cable is one of the most effective support equipment, it has been extensively used for ground reinforcement in underground coal mine roadways around the world (Brown, 1999; Kang et al., 2015; Peng & Tang, 1984), it is because that the anchor cable is economical, easily installed and reliably support equipment, it increase the stress and the frictional strength across joints, causing loose blocks or thinly stratified beds to become wedged together and act as a composite beam (Goel et al., 2007; Karanam & Dasyapu, 2005; Mark, 2000), and it plays a significant role in controlling the volume of the plastic zone (Yu et al., 2020). In most cases, to ensure the stability of roadway, more extra anchor cables would be used for the roadway support, obviously, it will result in many waste, and it is not economy, thereof, how to reduce the anchor cable used, and the stability of roadway can be guaranteed as well should be paid more attention to.