Soil nailing

In this paper main emphasis is put on methods for improvement of soft ground with the use of vibro compaction methods, Vacuum consolidation, Soil nailing, Grouting methods and dewatering methods. Vibro-compaction increases the density of the soil by using powerful depth vibrators. Vacuum consolidation is used for improving soft soils by using a vacuum pump. Preloading method is used to remove pore water over time. Vibro replacement stone columns improve the bearing capacity of soil whereas Vibro displacement method displaces the soil. Many ground improvement techniques are available to suit the particular needs of soil type, structure type and performance criteria. These techniques offer cost effective solutions, whilst reducing construction period considerably. Furthermore, these techniques also offer environmental friendly systems, which is important for urban areas.

Soil nailing has become a widely accepted method and offers a practical solution towards construction of permanent retaining wall, slope stabilization and protection of existing cuts from failure. In Malaysia, soil nailing is typically performed on cut slope and installed with grouting as preventatives method due to erosion problem. However, although the effectiveness of soil nailing system may be well understood by practitioners, the slope failure and collapses of deep excavation are continuously occurs, especially for the construction in the earthquake zone. Malaysia has numerous experiences of earthquake even this country has been categorized as low seismicity group. Hence, it is become important in the scope of geotechnical engineering to analyze and study the effect of earthquake to soil nailing systems in Malaysia. Aims of this paper are to focus and study this technical issue using the application of finite element program. This research study selects PGA of 0.08g based on th...

In this research work slope stability is done by using well known topic of geotechnical engineering which is “Soil Nailing”. A lab based physical model is constructed for this research work. We deal with different types of facing materials for soil nailed slope which are Aluminium diamond shaped wire mesh, Galvanized iron wire mesh, Polyester geogrid, HDPE sandwiched triaxial geogrid and HDPE hexagonal mesh. To find out the strain produced in nails a flex sensor is attached on nail surface which show defection on loading whose values are taken by multimeter. Settlement and displacement of soil mass is easily visible from the perpex sheet as perpex sheet is used as two walls of the physical model. Bottle jack of capacity 5 ton is used for loading purpose

Typically, temporary soil nailing systems are not required to provide for design level earthquake occurrences consistent with the building or structure being constructed inside the excavation. However, the seismic response of the permanent soil nail walls during the earthquakes should be evaluated. On the other hand, evaluation of 3D response of soil nailing walls have some strange manners that should be considered in the numerical analysis. In this paper, numerical simulations of soil nail walls under vibrational input have been carried out, and the results are compared with the function of soil nail walls under ordinary statistical loading. The behaviour of geometry of nails are mentioned under static and seismic analysis. After that some investigations are carried out to find respond of soil nailing walls in some 3D excavation forms. The analysis is performed with finite difference software called FLAC3D. The results are prepared as lateral displacement of the walls and normalized maximum tensile forces for nails. These results can demonstrate the behavior of external and internal resistance of soil nail walls under seismic and static analysis. The deformation of wall under the static and dynamic manner varies in a wide range. On the other hand, tensile loads that are produced in nails under the static manner are namely 50% less than the dynamic manner.

Los muros anclados son utilizados para la construcción de muros de retención o para asegurar cortes en excavaciones. Los anclajes son usados para proporcionar una precarga de los sistemas estructurales aplicando tensión por medio de sistemas hidráulicos al tendón del anclaje, que puede ser tanto barras como cables de acero de alta resistencia. El cable o barra entonces será enlazado al suelo o roca por medio de una lechada cemento. La precarga aplicada servirá entonces para limitar el desplazamiento de la estructura, esto con el fin de evitar asentamiento que puedan ocasionar el daño en estructuras existentes o la falla de un corte generado ya sea por una excavación. Los anclajes varían en su longitud dependiendo tanto de la estratigrafía del sitio y sus condiciones geológicas, como la geometría y cargas a las que se ven sometido, por lo que los anclajes pueden ser de típicamente de 30 ton a 60 ton. Los anclajes permanentes incorporan una variedad de sistemas de la protección contra la corrosión que son determinados por las condiciones específicas del sitio de trabajo, al presupuesto y a la duración de la obra. Fig. 1 Muro Anclado en proyecto ubicado en Sabana Oeste Como se mencionó anteriormente los anclajes empiezan a trabajar en el momento que son sometidos a la precarga, sin la necesidad de que se deba dar un desplazamiento en el elemento a estabilizar. Por lo que su función en sitios donde el talud se encuentra en colindancia con estructuras existentes es muy efectiva, ya que evita el daño de las estructuras por asentamientos.

The restraining effects in the sand subgrade under the footing can be provided by inserting the vertical
reinforcing bars beyond the footing base without disturbing
the subgrade below the footing. This technique of soil reinforcement can be quite beneficial for the footings where
improvement is necessary. This paper presents the results
of model square footing tests with vertical reinforcements
inserted into the sand subgrade beyond the footing base
only. The variables selected for the investigation were
spacing of vertical reinforcement, extent of reinforcement
from the edge of footing, length of reinforcement, diameter
of reinforcement, width of footing and surface characteristics
of the reinforcement. The values of theoretical
bearing capacity of reinforced sand subgrade were determined using the method of slices and compared with experimental results. It was found that results were
comparable particularly when the length of reinforcement
and extent of reinforcement were two times the footing
width.

U radu su opisane analize rješenja kosine usjekna na autocesti. Primijenjene su tri metode izrade potporne konstrukcije, a to su armirano tlo HDPE geomrežama, čavlanje i potporni zid u dužini 20 m. Visina konstrukcije iznosi 10 m. Pri proračunu za izradu armiranog tla i čavlanja primijenjeni su AASHTO standardi, a potporni zid je proračunat u skladu sa EN 1997-I normama. Sve metode su implementirane u software-ski paket Plaxis koji je korišten za istraživanje. Na osnovu provedenih analiza izvršen je izbor rješenja kao najpovoljnijeg.

There are various methods for stabilizing excavations in urban areas which one of them is the nailing method. Designing a nailing system and analyzing the performance of excavations is done by various software applications. One of these computer programs is PAXIS software which run based on the finite element method (FEM). In the present study, a numerical analysis of the performance of the excavations was investigated under different soil model and the most appropriate model was introduced. In addition, the excavation performance was evaluated based on certain designing conditions affected by the soil resistance specifications (cohesion and internal friction angle) and surcharge. The results indicated that, using an appropriate behavioral model which contains increasing soil stiffness with depth, shows results close to reality. They also indicated that under certain designing conditions, the lateral deformation of the soil nail wall and ground settlement decrease as soil resistance...

Innovative recessed soil nails were used on a conservation slope in Aberdeenshire to help stabilise the slope and provide a fully green vegetated slope finish. Fifteen hundred soil nails were employed on a 300m long section of the existing unstable coastal slope at Stonehaven as part of landslip preventive works. Soil nail heads were designed as individual recessed concrete pads set into the slope surface, buried beneath pre-seeded bio-degradable grow bags and erosion control matting. In this way the pre-existing fully vegetated appearance was retained as requested by the local residents, planning authority and client. This design provided both local and global stabilisation of a 40m high slope, sustainability in design, limited disruption to local residents, and aesthetic requirements of this conservation slope. This paper concentrates on the innovative soil nail head design, not normally used in the UK, to both stabilise the slope and provide full vegetation cover.

A total of 45 locations of slope failures occurred along Jalan Baru Gap to Fraser Hill, Pahang. Of the 45 locations of slope failures, only 31 locations were repaired using soil nails. At each location, only one pull out test was carried out. This study involved the results of the pull out tests at all the 31 locations and the results were obtained from Public Works Department, K.L. The maximum pull out load during the test was 90 kN and the displacement at 90 kN load must be less than 10mm for the test to be considered satisfy the specifications. The main purpose of this study is to determine the characteristics of the pull out test on soil nail and the interaction between the soil nail and the soil.

This paper addresses soil reinforcement techniques employing semi- rigid inclusions called nails, hence the term soil nailing. It was intuitively applied for the first time in Brazil in 1970 by tunnel contractors in Sao Paulo. Since then, several soil nailed structures have been constructed successfully. The development of methods of analysis in Europe and North America is reviewed; the application of those methods in Brazil has led to more economical and safer structures. This paper briefly presents the historical development and the use of soil nailing in Brazil. Differences and similarities with traditional techniques are discussed and some examples are given. (A)

In this paper, numerical simulations of soil nail walls under simulated vibrational input have been carried out and the results are compared with the function of soil nail walls under ordinary statistical loading. The behavior of geometry of nails is mentioned under static and seismic analysis. The analysis is carried out with finite difference software called FLAC. The results are prepared as lateral displacement of the walls and normalized maximum tensile forces for nails. These results can demonstrate the behavior of external and internal resistance of soil nail walls under dynamic and static analysis. The deformation of wall under static and dynamic manner varies in a wide range. On the other hand tensile loads that are produced in nails under static manner are namely 50% less than the dynamic manner.

The present study aims at investigating the pull-out resistance efficiency of single and double nails. In sandy soils, where the distance between nails is less than the minimum required distance, the pull-out resistance is reduced. Besides, when the minimum required distance is met, the nail pull-out capacity is not under the effect of the neighboring nail. The parameters affecting the efficiency of the nail group are investigated in this study; including, a type of nail, nail intervals and overburden type of pressure. One of the most important parameters – in order to determine the efficiency of the group – is the nail surface roughness coefficient, which is dependent on factors such as the number of the ribs in each unit length of nail and, also, the depth of the ribs to the size of soil particle. The nail surface roughness coefficient is used to determine the apparent friction coefficient on the nail surface. In all tests, the pull-out force-displacement curve had distinct peak v...

ABSTRACT Displacement measurement of the soil nail walls is a very important task in monitoring tiny movements in excavations to prevent disastrous accidents like wall collapsing. In building construction projects, this is usually done by either micro-geodesy or accurate instrumentation methods. In this research, for the first time, the use of close range photogrammetry in displacement measurement of the soil nail walls has been proposed and experienced. For this, a photogrammetric system was designed, implemented and evaluated. Proposed system with three separate methods for displacement measurement, which one of them was submitted for the first time (CPDA), was implemented. The evaluation results the accuracy of 3 mm is achievable in determining the point coordinates with a precision of 8 mm in displacement measurement of soil nail walls. Due to the efficiency, low cost, high accuracy, high speed of observations along with the simplicity of implementation of close range photogrammetry, it is suggested as a proper alternative to the traditional methods.