Behavior of the Underpinning of a Building in Venice

This paper examines the behavior of a building constructed in 1960 and subject ever since the end of its construction to considerable total and differential settlements in time. Monitoring of the building revealed an increase in the settlement rate during the first years of the 1990s, such as to require underpinning with micropiles in 1992. In the first part of the paper, the evolution of settlements until the beginning of the restoration is analyzed, and real and anticipated behaviors are compared. In the second part, the behavior of the building during and after micropile underpinning is explained. Back-analysis was carried out, adopting tridimensional finite element analyses, in order to interpret behavior before and during underpinning

Foundations for Large Embankments

This report deals with problems connected with the design and construction of two levees built on thick soft compressible soils in the Po Delta. Settlement and pore pressure measurements in foundation soils, taken for about four years during and after construction by means of complete geotechnical instrumentation, were compared with results obtained through various methods during both design and back-analysis phases. Back-analysis was carried out using numerical simulations with finite-element programs. Considerations of the problems of the global stability of the embankments during the various construction phases are also presented

A Particular Foundation Problem on a Waste Fill

The construction of a new aerobic water treatment system for polluted water in the ENJCHEM chemical plant at Mantova (N. Italy), emphasized a particular foundation problem; the complete treatment system, covering a surface area of 12000 m2, lies on a zone once used as a waste fill, 4-6 m deep and composed of various materials from industrial processing, with highly variable origins and poor resistance characteristics. The main structures are: steel tanks with fixed roofs, and gauge and settling tanks, of 30 and 26 m diameter respectively, each containing a 15-m water head, reinforced concrete sediment thickeners and degassing basins with diameters of 15 and 35 m, each containing a 3-4 m restricted water head. The requirement to avoid contact between waste materials and the natural soil beneath excluded the possibility of deep foundations on piles. Shallow foundations were therefore necessary; 4-8 m preloading embankments were designed in relation to the characteristics of the fill and the subsoil, working loads, and the need to limit settlements and distortions. The design criteria of preloading, measurements of embankment settlements (400-700 mm) and main structures during hydraulic testing are reported and discussed

Behavior of Direct Tower Foundation on Improved Soil

The paper presents the foundation behaviour of a 146-m telecommunications tower situated near Verona in Italy, with foundation soils characterized as a thick deposit of alluvial gravels and sands. In order to limit total and differential settlements of the tower it was decided to improve the foundation soil with jet-grouting columns. Predictions on the behaviour of the structure and the foundation soil were performed with an axisymmetric finite-element model adopting an elastic linear constitutive law. Soil moduli were obtained from the results of a cross-hole test and from Standard Penetration Tests; jet-grouting columns behaviour was estimated from load and borehole tests. Calculated settlements in the construction stages are compared with the measured ones

Improvement of Mechanical Properties of Soft Soils by Use of a Pre-Loading Embankment

A preloading embankment, and its foundation soil, have been closely monitored in the Po river delta (Italy). After showing that the complete consolidation of the peaty and clayey soil has taken place, the shear strength increase measured with various tests has been considered and analyzed