Reinforced Earth

In this thesis, it is aimed to contribute to train soil improvement specialists by
explaining soil improvement techniques which become a common need in today’s
civil engineering applications. In accordance with this purpose, first of all
classification of the soil improvement techniques of the problematic soils is
mentioned. Selected classification principles for categorizing the techniques which
mentioned in the thesis are explained. The subjects are emphasized such as the soils
on which the techniques can be applied, the applications of the techniques in civil
engineering, the special equipments required for the applications, the construction
methods of the application, advantages and disadvantages of these applications.
Besides, the theories- related to design of the methods- are explained with sample
problems. Some cases in which the techniques have been applied in Turkey and the
World are presented as case studies. Finally, in an attempt to make easier the
selection of appropriate technique among the mentioned ones, a guideline has been
developed by considering parameters such as the purpose of improvement,
appropriate soil type, applicable effective depth, applicable economic area, advantages, disadvantages, seismic performance and costs of the methods

Observation and numerical modeling of MSE test wall is presented here. The 6m wide and 3.2m high wall with 10cm thick precast concrete face elements and reinforcement length of 2.15m was built on construction site of Motorway 5C in Bosnia and Herzegovina. Welded wire mash Q335 was used as reinforcement. Compared to other MSE test walls, the presented work is unique due to the choice of backfill material consisting of course crushed stone aggregate ranging from ~0-100mm in size whereas most of other published studies used sandy backfill. Two weeks after the construction, the top of the wall was loaded with additional overburden weight 1,5m in height (~30 kPa). The forces in reinforcement were measured with a series of embedded sensors and deformation with an inclinometer installed in the middle of the wall length, including geodetic survey of wall face. Experimentally observed results are compared to the analysis results obtained from numerical model created using Plaxis software.

The soil which is generally weak and possesses high deformation values in vast areas are covered with soil deposits having low shear strength and high compressibility. Clayey sands (SC) mostly tend to exhibit high liquid limit (LL) and plastic limit (PL). The technique of combining any two materials of different strengths to form a composite single material of greater strength is the frequent procedure followed in civil engineering practice. The soil is quite good in compression and weak in tension can't bear the load alone. When a material of high tensile strength is introduced in the soil as a reinforcing material, the soil turns into a composite material and tends to possess relatively very high strength and attains the ability to carry loads of heavyweights. Reinforced earth is a technique primarily used to increase the ease of construction and cost-effectiveness. Keeping in view the research findings outlined about, in the present experimentation, it was carried out to investigate the efficacy of plastic gunny bags stabilizing the weak soil, thereby, improving the shear strength and bearing capacity of the soil. A systematic methodical process followed involving experimentations in the laboratory under controlled conditions. It was observed that 1cm thickness and 0.03mm thickness of plastic gunny bags with clayey sand effectively improved the shear strength and bearing capacity of the soil.

Shallow foundations are constructed on fills and over weak/compressible soils, the primary problem will be large settlements. In such cases, deep foundation is generally recommended which increases cost of the structure. In recent times, Ply soil' which is formed introducing randomly distributed fibers results in comparatively more homogeneous soil. Natural fibers such as coir fibers have been successfully introduced. In the present study, an attempt has been made to surface treat the coir fiber to make it water repellant, henceforth and their performance when introduced in soil is compared with un treated fibers. Further, model footing tests on clayey soil overlying a loose stratum and reinforced with optimum percentage (0.5%) of treated coir fibers and untreated coir fibers were used with varying H/B ratios in order to determine the maximum optimum depth of fiber reinforcement in the clay layer obtained using model footing test. Loose soil deposit has been simulated by compacting saw dust in prefabricated steel tank. Soil reinforced with optimum percentage of treated fibers at various H/B ratios of 0.2, 0.4, 0.6, 0.8, up to 2 Keywords—BC soil, Coir fiber RDF, model footing. U/B ratio

Soil reinforcement technique is one of the most popular techniques used for improvement of poor soils. Metal strips, synthetic geotextiles, geogrid sheets, natural geotextiles, randomly distributed, synthetic and natural fibers are being used as reinforcing materials to soil. Further, the soil reinforcement causes significant improvement in tensile strength, shear strength, other properties, bearing capacity as well as economy. This is a relatively simple technique for ground improvement and has tremendous potential as accost effective solution to many geotechnical problems. The objective of the present investigation is to determine the effect of introducing coir mat reinforced soil layer over soil stratum and effect of size of the opening of coir mat on shear strength characteristics of sand will be analysed.

The paper presents the results of experimental studies with regard to the response of small scale model strip footings resting on the surface of wrap-around reinforced soil retaining walls constructed using locally available sand as backfill and geotextile as reinforcing elements. Number of reinforcing layers and footing size were varied to find their influence on the bearing capacity and load deformation (both vertical and lateral) characteristics of the walls. It is found that the ultimate bearing capacity of the footings and initial tangent modulus increases with increase in the number of reinforcing layers but the initial tangent modulus decreases with increase in footing size.

The paper presents the results of experimental studies with regard to the response of small scale model strip footings resting on the surface of wrap-around reinforced soil retaining walls constructed using locally available sand as backfill and geotextile as reinforcing elements. Number of reinforcing layers and footing size were varied to find their influence on the bearing capacity and load deformation (both vertical and lateral) characteristics of the walls. It is found that the ultimate bearing capacity of the footings and initial tangent modulus increases with increase in the number of reinforcing layers but the initial tangent modulus decreases with increase in footing size.