Mats, foundation

Figure 18.5 Graduation curve for soil beneath mat foundation.

Fig. 8-3. Types of mat foundations, (a) Floating mat (6) mat for supporting high-temperature equipment.

Mats, which generally cover the total area of the platform, are usually A-shaped. The thickness is about 3 m. The performance of mat-supported rigs has been described by Hirst et al. (1976), and by Young et al. (1981). They have the disadvantages that they require a relatively level bottom and that they are affected by differential settlements caused by eccentric or cyclic loading and by scour. However, the advantage is that a mat foundation can be used in very soft soil because of the large surface area. 

The soft soil is taken to consist of five layers, from a soft one at the surface to a compacted layer at the bottom and assumed to overlie a dense sandy soil that acts as the engineering bedrock where the ground acceleration is defined. The soil layer properties are described in Table 25.1. For simplicity, aU concrete slabs and the fotmdation mat are considered to have a uniform thickness of 0.5 m and are modelled as 3D elastic solid elements with unit weight 25 kN/m, elastic modulus 28,000 MPa and Poisson s ratio 0.2. The finite element discretization was carried out using 3D-nonlinear solid element for the soil and 3D-elastic solid element for RC slabs and the mat foundation, as depicted in Fig. 25.5. 

For foundations with friction piles or mat foundations on soi or other elastic base support conditions. 

Foundation checks depend on the type of foundation (mat foundation, foundation beams, spread footings, pile foundation, etc.) and consist of general stability checks (overturning, sliding), soil bearing capacity checks, comparison of absolute and differential settlements to allowable values, and calculation of reinforcement for the reinforced concrete elements. 

Students interest in learning about chemical reactions increased, which is due to three main factors that ate incorporated in the LON approach (1) Everyday life situations ate the foundation of the learning process. (2) The learning process involves mat r students activities. (3) Chemical reactions are consistently presented in all three types of representation. 

Foundations are always constructed of reinforced concrete. Blast resistant buildings can be supported on pited or soil supported mats. Spread footings arc used with a grade beam system to minimize relative displacements between individual footings,... 

For high, heavy tanks, a foundation ring may be needed. Prestressed concrete tanks are sufficiently heavy to require foundation rings. Foundations must extend below the frost line. Some tanks that are not flat-bottomed may also be supported by soil if it is suitably graded and drained. When soil does not have adequate bearing strength, it may be excavated and backfilled with a suitable soil, or piles capped with a concrete mat may be required. 

The author wishes to thank his many collaborators and colleagues in this field, almost too numerous to mention. However, special thanks to the collaborators and colleagues at both IBM and Denmark and to Mats Persson, Geert-Jan Kroes, and Bret Jackson who have read parts of this review and offered comments. Nevertheless, the opinions presented here are the sole responsibility of the author. Discussions and arguments with many of the participants in this field, both in print and over many a bottle of wine/beer, and in many parts of the world, over the past 25 years have led to the opinions presented in this review. It has been a fun journey of discovery. Of course since this is still an active research field, some of the concepts/opinions are not yet etched in stone, but hopefully time will prove those presented here to be more fact than fiction. The author also wishes to thank the Alexander von Humboldt foundation for support of visits to Berlin where this chapter was initiated and Bonnie for her patience while this chapter was written. 

In every tissue of the body cells are cemented into place by a variety of proteins and proteoglycans which constitute the extracellular matrix (ECM). This protein mat provides a secure foundation for the cells, but its components also have effects on cell function and differentiation. Cellular attachment is mediated by a family of matrix receptors found on the cell surface called integrins. Integrins secure the cell to the matrix, and determine cell shape, migration and spread. 

We thank Mrs. Diana Ayerhart (Mayo Clinic) for her help in preparing this manuscript. We also thank Mayo Foundation, Beckman Instruments, and Fiimigan MAT for their support. 

J. P. Gould, J. Bender, and P. Phillips, Bioremediation of Metal-contaminated Water with Microbial Mats, Pollution Prevention for Process Engineering, P. E. Richardson and B. J. Scheiner (eds.). Engineering Foundation, AIChE, New York, 1996a, pp. 175-182. 

The type of foundation chosen will depend on the load to be supported and the bearing capacity of the soil, i.e., the unit loading or pressure. The intensity of pressure on the soil should ideally be uniform over the entire foundation. This is possible to achieve on hard rock, gravel, or good sand, and foundations of the footing or mat type are specified. In the case of compressible soils, such as mud, silt, or clay, differential settling occurs and -piling must be used. 

Mats. In designing foundations for some structures in low-load-bearing soils the combined area of spread footings approaches that of the supported structure. It is then more practical to use one large reinforced concrete slab or mat under the entire structure. In Fig. 8-3a typical mat construction for support of walls, columns, and flat-bottomed storage tanks is illustrated. A ventilated concrete mat and vertical support foundation for high-temperature supported structures is shown in Fig. 8-36. 

Young, A. G., House, H. R, Herlfrich, S. C., and Thumer, D. (1981), Foundation performance of mat-supported jack-up rigs in soft clays. Proceedings of the 13th Annual Offshore Technology Conference, Houston, TX, 4, pp. 273-284. 

The containment is a prestressed reinforced concrete structure in the shape of a cylinder with a torispherical dome and a flat foundation mat. The cylindrical portion of the containment is prestressed by a post tensioning system consisting of horizontal tendons and vertical tendons. The dome is prestressed with crossed tendons that are anchored at the dome stiffening ring girder. The foundation mat is conventional reinforced concrete. 

The interior surface of the containment is steel-lined for leaktightness. A protective layer of concrete covers the portion of the liner above the foundation mat. 

The prestressed concrete vessel has a cavity with a diameter of about 12 and a depth of about 38 m, containing some 3,300 m of water. The concrete vessel is a monolith with a cross-section of about 27 and a height of about 43 m. It is anchored to the foundation mat structure by means of prestressing tendons. The pressure retaining capability of the vessel is ensured by a large number of prestressing tendons - partly horizontal tendons run around the cavity, partly vertical tendons run from the top to the bottom, - and by reinforcement bars. 

A free standing configuration for the Reactor Pool, resting on a common foundation mat, but structurally decoupled from the RB, designed for a RG. 1.60 Safety Shutdown Earthquake excitation anchored to 0.3 g, presents reasonable wall thicknesses and reinforcing bar densities. 

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