- Email: [email protected]
Membranes in ground engineering
Membranes in ground engineering P.R. Rankilor
John Wiley and Sons Ltd (1981) £19.50 In any civil engineering project the behaviou$ of the ground is always a most important consideration both during and after construction. Most civil engineering structures are built of, or on, a compressible material known as soil. The properties of this material are rarely ideal for most applications and hence methods of improving them are always being sought. It has been found that the inclusion of fabric membranes in soil systems can in some cases provide technical improvements resulting in lower overall costs for the construction works. This has led to the development of a wide variety of membranes specifically designed for use in civil engineering. The role the membrane plays in improving the behaviour of the soil depends upon the application, but in general four operational functions are recognized: separation; filtration; drainage along the membrane and; reinforcement. In a given application one or more of these functions will dominate and since the characteristics of membranes vary widely, some will be capable of performing certain functions better than others. The choice of membrane is clearly important in the efficient and safe design of soil/membrane composites. Although the basic types of membrane are limited to about ten, there are over 130 different membranes commercially available which can make this choice difficult. Even if the membrane chosen is best suited for a particular application, the overall design of the composite and the construction techniques employed during placement of the membrane can be critical to its performance. The increased use of membranes during the past ten years has given rise to many novel designs, and construction techniques. Also a great deal of research has been carried out to examine the properties of various types of membrane and the performance of membranes in soil systems, which , has generated numerous publications.
exposure effects on plastics, little discussion is given to soil/ membrane interaction, particularly with reference to the separation and reinforcement functions. The final Chapter in this section of the book deals with the types of membrane available and includes illustrations of over 130 types of membrane with the manufacturer's published data and a standardized description by the author. A list of addresses of manufacturers and sales organisations is also given. The illustrations of different membranes are most comprehensive and constitute over 20% of the book; unfortunately a small proportion of the manufacturer's published data have not been translated into English. The second section of the book is devoted to the design of permeable membranes in soil systems, and includes drain filters, river and marine defences, land reclamation, permanent and temporary road construction and miscellaneous applications. Both design and construction techniques are discussed, drawing much from the author's experience with many useful design charts and illustrations. Unfortunately the author does not attempt to discuss any of the miscellaneous applications for membranes but instead gives a number of illustrations from manufacturers' published literature. The final section deals with laboratory testing. Most of the tests discussed are carried out for quality control purposes and hence involve testing the membrane in isolation from the soil. More discussion could have been devoted to tests that examine the behaviour of the soil membrane composite. Overall the book is well laid out with excellent line drawings and a very useful catalogue including photographs of most types of membrane commercially available. Unfortunately the author has given an oversimplistic view of the soil mechanics aspects involved in membrane design with little discussion on the behaviour of the soil membrane composite outside the field of filtration. The section dealing with membrane design yields little objective analysis particularly with reference to the advantages and limitations of membrane inclusions. There is, however, useful guidance to the methods of placing membranes into soil systems which is based much on the author's experience.
Unfortunately very little has been published that brings together the types of membrane available, the choice of membranes, the design of membrane inclusion in soils systems, and the constructional techniques involved. Rankilor has attempted to fill this gap by producing a text-book on membranes in ground engineering aimed specifically at practising engineers. The book is divided into three sections. The first section deals with the general aspects of membranes. After a brief historical review an elementary treatment of the soft mechanics associated with membrane design is given in Chapter 2. Althouth in may applications a total-stress soil mechanics approach is satisfactory, it is disappointing that more emphasis is not given to the concepts of effective stress, particularly in the discussion of soil strength parameters. The text here implies that the ¢ = 0 condition for cohesive soils is a fundamental property of the soil whereas it is a consequence of the test conditions. This is followed by a discussion on the theoretical functions of membranes in the soil environment in Chapter 3. The important topic of durability of membranes placed in soil is dealt with here, together with other membrane properties, such as creep strength and permeability. Apart from the aspects of soil
102
M.C. Matthews
Fibre composite hybrid materials Edited by: N.L. Hancox
Applied Science Publishers Ltd (1981) £22.00 Books of a general nature on composite materials are to be welcomed and in spite of the mention of hybrids in the title much of this book could be used as an introduction to the whole field of composites. Hybrids which are composites containing two or more types of reinforcing fibre are increasingly being used to optimize material properties and cost of structures. As the book explains, a relatively small amount of carbon fibres added to a glass fibre/resin composite can dramatically increase the modulus, sometimes
COMPOSITES. APRI L 1982
John Wiley and Sons Ltd (1981) £19.50 In any civil engineering project the behaviou$ of the ground is always a most important consideration both during and after construction. Most civil engineering structures are built of, or on, a compressible material known as soil. The properties of this material are rarely ideal for most applications and hence methods of improving them are always being sought. It has been found that the inclusion of fabric membranes in soil systems can in some cases provide technical improvements resulting in lower overall costs for the construction works. This has led to the development of a wide variety of membranes specifically designed for use in civil engineering. The role the membrane plays in improving the behaviour of the soil depends upon the application, but in general four operational functions are recognized: separation; filtration; drainage along the membrane and; reinforcement. In a given application one or more of these functions will dominate and since the characteristics of membranes vary widely, some will be capable of performing certain functions better than others. The choice of membrane is clearly important in the efficient and safe design of soil/membrane composites. Although the basic types of membrane are limited to about ten, there are over 130 different membranes commercially available which can make this choice difficult. Even if the membrane chosen is best suited for a particular application, the overall design of the composite and the construction techniques employed during placement of the membrane can be critical to its performance. The increased use of membranes during the past ten years has given rise to many novel designs, and construction techniques. Also a great deal of research has been carried out to examine the properties of various types of membrane and the performance of membranes in soil systems, which , has generated numerous publications.
exposure effects on plastics, little discussion is given to soil/ membrane interaction, particularly with reference to the separation and reinforcement functions. The final Chapter in this section of the book deals with the types of membrane available and includes illustrations of over 130 types of membrane with the manufacturer's published data and a standardized description by the author. A list of addresses of manufacturers and sales organisations is also given. The illustrations of different membranes are most comprehensive and constitute over 20% of the book; unfortunately a small proportion of the manufacturer's published data have not been translated into English. The second section of the book is devoted to the design of permeable membranes in soil systems, and includes drain filters, river and marine defences, land reclamation, permanent and temporary road construction and miscellaneous applications. Both design and construction techniques are discussed, drawing much from the author's experience with many useful design charts and illustrations. Unfortunately the author does not attempt to discuss any of the miscellaneous applications for membranes but instead gives a number of illustrations from manufacturers' published literature. The final section deals with laboratory testing. Most of the tests discussed are carried out for quality control purposes and hence involve testing the membrane in isolation from the soil. More discussion could have been devoted to tests that examine the behaviour of the soil membrane composite. Overall the book is well laid out with excellent line drawings and a very useful catalogue including photographs of most types of membrane commercially available. Unfortunately the author has given an oversimplistic view of the soil mechanics aspects involved in membrane design with little discussion on the behaviour of the soil membrane composite outside the field of filtration. The section dealing with membrane design yields little objective analysis particularly with reference to the advantages and limitations of membrane inclusions. There is, however, useful guidance to the methods of placing membranes into soil systems which is based much on the author's experience.
Unfortunately very little has been published that brings together the types of membrane available, the choice of membranes, the design of membrane inclusion in soils systems, and the constructional techniques involved. Rankilor has attempted to fill this gap by producing a text-book on membranes in ground engineering aimed specifically at practising engineers. The book is divided into three sections. The first section deals with the general aspects of membranes. After a brief historical review an elementary treatment of the soft mechanics associated with membrane design is given in Chapter 2. Althouth in may applications a total-stress soil mechanics approach is satisfactory, it is disappointing that more emphasis is not given to the concepts of effective stress, particularly in the discussion of soil strength parameters. The text here implies that the ¢ = 0 condition for cohesive soils is a fundamental property of the soil whereas it is a consequence of the test conditions. This is followed by a discussion on the theoretical functions of membranes in the soil environment in Chapter 3. The important topic of durability of membranes placed in soil is dealt with here, together with other membrane properties, such as creep strength and permeability. Apart from the aspects of soil
102
M.C. Matthews
Fibre composite hybrid materials Edited by: N.L. Hancox
Applied Science Publishers Ltd (1981) £22.00 Books of a general nature on composite materials are to be welcomed and in spite of the mention of hybrids in the title much of this book could be used as an introduction to the whole field of composites. Hybrids which are composites containing two or more types of reinforcing fibre are increasingly being used to optimize material properties and cost of structures. As the book explains, a relatively small amount of carbon fibres added to a glass fibre/resin composite can dramatically increase the modulus, sometimes
COMPOSITES. APRI L 1982