The effect of group behavior on the pull-out capacity of soil nails in high plastic clay

Akış, Ebru
Soil nailing technique is widely used in stabilizing roadway and tunnel portal cut excavations. The key parameter in the design of soil nail systems is the pull-out capacity. The pull-out capacity of the soil nails can be estimated from the studies involving similar soil conditions or can be estimated from the empirical formulas. Field verification tests are performed before the construction stage in order to confirm the parameter chosen in the design of soil nailing system. It is reported in the literature that, the pull-out resistance of a soil nail in sand should be reduced for the nails installed closer than a specific minimum distance, whereas no such requirement have been discussed for nail groups in clays. v In this study, the pull-out resistance of nails in high plastic clay are tested to investigate the influence of nail spacing in group applications. The laboratory set-up for the pull-out tests is composed of an aluminum model box (300mm (w) x 300mm (h) x 500 mm (l)), soil sample, reinforcements, pull-out device, overburden pressure applicator and monitoring device. A series of pull-out tests has been carried out on single nails and group of nails with spacings 2 and 6 times the diameter of a nail in order to observe the group effect on the pullout capacity of the nails. The nails are located into their positions during the placement of clay into the box. Within the limitations of this study, it is observed that, there is a reduction in the pull-out capacity of the central nail in 2Ø spaced group. The pull-out capacity of the central nail in nail group with 6Ø spacing, is not affected from the neighboring nails. In all tests, the plots of pull-out load on nail versus nail displacement show that, the peak value of load is followed by a sharp reduction. The peak pull-out load is mobilized at first few millimeters of the nail displacements. A 3D finite element program is used for numerical analyses of the experiments. The measured pull-out capacity of the soil nails are compared by the results of simulated forces obtained from these analyses. By and large, the agreement between the tests and the numerical analyses is observed to be satisfactory. The details of the numerical models are briefly presented in order to give insight into numerical modeling of soil nails in real applications.


Analysis of mechanical behavior of high performance cement based composite slabs under impact loading
Satıoğlu, Azize Ceren; Gülkan, Polat; Department of Civil Engineering (2009)
Studies on the behavior of steel fiber reinforced concrete (SFRC) and slurry infiltrated fibrous concrete (SIFCON) to impact loading have started in recent years. Using these relatively new materials, higher values of tensile and compressive strength can be obtained with greater fracture toughness and energy absorption capacity, and therefore they carry a considerable importance in the design of protective structures. In this thesis, computational analyses concerning impact loading effect on concrete, steel...
Assessment of the ground subsidence and lining forces due to tunnel advancement
Karamanlı, Ömer; Çetin, Kemal Önder; Department of Civil Engineering (2009)
The use of sprayed concrete lining is common in tunneling practice since it allows the application of non-circular tunnel sections and complex tunnel intersections. Low capital cost of construction equipment is also an important factor for the selection of the sprayed concrete lining. In general the use of sprayed concrete lining is referred as New Austrian Tunneling Method (NATM). Depending on the requirements regarding tunnel heading stability and limitations on tunneling induced soil displacements, tunne...
The effect of shape memory alloys on the ductility of exterior reinforced concrete beam-column joints using the damage plasticity model
Halahla, Abdulsamee M.; Abu Tahnat, Yazan B.; Almasri, Amin H.; Voyiadjis, George Z. (Elsevier BV, 2019-12-01)
Using shape memory alloys (SMA) bars can significantly enhance the ductility of exterior reinforced concrete joints, where they can replace the conventional steel reinforcement. This research focuses on studying the effect of using SMA on the ductility capacity of exterior reinforced concrete beam-column joints at different column axial load levels. Finite element analysis was carried out and compared with the experimental results from the literature for verification purposes, and both were compared with th...
Investigation of strenghthening techniques using pseudo-dynamic testing
Kurt, Efe Gökçe; Özcebe, Güney; Department of Civil Engineering (2010)
Pseudo-dynamic testing was employed to observe the seismic performance of three different retrofit methods on two story three bay reinforced concrete frame structures. The three test frames have hollow clay tile (HCT) infills in the central bay. All of the test frames represent the seismic deficiencies of the Turkish construction practice such as use of plain reinforcing bars, low strength concrete and insufficient confining steel. Two non-invasive and occupant friendly retrofit schemes suggested in the Tur...
Bonding efficiency of roller compacted concrete with different bedding mixes
Özcan, Sinan; Yaman, İsmail Özgür; Department of Civil Engineering (2008)
Roller Compacted Concrete (RCC) has rapidly evolved from a concept to a material and a process which is used throughout the world for faster and more economical construction of dams. Currently, there are more than 250 RCC dams, completed or under construction, in the world. On the other hand, currently, there are only two RCC dams completed (Suçatı and Cindere Dams) and two under construction (Beydağ and Çine Dam) in Turkey. RCC dams are constructed in a series of compacted layers usually 30 cm in thickness...
Citation Formats
E. Akış, “The effect of group behavior on the pull-out capacity of soil nails in high plastic clay,” Ph.D. - Doctoral Program, Middle East Technical University, 2009.