Analysis and Design Of Reinforced Earth Structures

Abstract

Reinforced earth is a composite material which is formed by the association of soil and tension resistant elements in the form of sheet, strips, nets or mats of metal, synthetic fabrics or fibre reinforced plastics and arranged in the soil mass in such a way as to reduce or suppress the tensile strain which might develop under gravity and boundary forces. The largest application of the soil reinforcement is for the construction of the earth structures with steep or vertical sides in lieu of the rigid retaining walls. Besides the technical superiority of the reinforced soil structures over the conventional R.C.C retaining structures, the technique is highly economical and time saving. This merit of reinforced soil enabled it in use in almost all civil engineering structures. The objective of this study is to understand the importance of reinforced earth technique in civil engineering structures. To study the importance of reinforced earth technique in improving the bearing capacity of soil under footing, an experiment has been done on the bearing capacity of geotextile reinforced soil. Geotextiles used in the experimental study is the woven geotextile. Experiment has been done for two condition i.e. unreinforced condition and reinforced condition. Loadsettlement curves are prepared for these two conditions. Using metal strips and geogrid, a reinforced earth footing has been designed to understand the improvement in bearing capacity of soil. The application of reinforced earth technology in retaining wall construction in place of R.C.C retaining walls results in substantial saving in cost as well as time. Reinforced earth retaining wall is designed using metal strip and geotextile as reinforcement. To study the economy of reinforced earth retaining wall, cost comparative study of reinforced earth retaining wall with R.C.C retaining wall is carried out. Quantity comparison of reinforced earth retaining wall with R.C.C retaining wall is also done. iv One of the methods of slope stabilization is the inclusion of the reinforcement in the slope and this can be done economically. Using reinforced earth technology, it is possible to construct very steep slope which lead to increase in usable space compared to unreinforced slope. Reinforced Soil Slope is relatively easy to construct, and have a lower cost relative to reinforced earth retaining walls. Using geogrid a reinforced earth slope is designed. Reinforced earth bridge abutment is designed using geogrid. Cost comparative study of reinforced earth bridge abutment with R.C.C bridge abutment is done. Quantity comparison of reinforced earth bridge abutment with R.C.C bridge abutment is also done. The content of major project is divided in to various chapters. Chapter 1 is of a general nature and it serves to introduce the topic. Chapter 2 gives the literature review carried out during work. Chapter 3 presents bearing capacity analysis of reinforced earth foundation. It also includes the experimental study on the bearing capacity of geotextile reinforced soil. Chapter 4 deals with the reinforced earth retaining wall. This chapter also includes the design principles of reinforced earth retaining wall. In chapter 5, design of reinforced earth slopes is presented. Chapter 6 presents the effect of reinforced earth technology on the bridge abutment. Chapter 7 gives the cost comparative study of reinforced earth structures with R.C.C structures. Finally summary, conclusion and future scope of work are given in chapter 8.