Two History Cases of Innovations

In late 1970s and through 1980s the Soviet Government and the Communist Party encouraged engineers and scientists to develop innovations, to implement them in order to optimize and to increase the effectiveness of the national economy. “The economy must be economical” was the slogan of this policy. The R@D programs were well funded by the State. The paper describes two failures, linked up with implementation of cost-saving innovations: explosion of a 10,000 m3 liquid ammonia storage tank, and failure of a raft footing on largely spaced piles

Application of Simplified Models to Qualitative Geotechnical Analysis

The paper describes an approach for qualifying soil-structure systems behavior, using simple numeric models – “geotoys”, reflecting the main features of the systems behavior and enabling numeric simulation of various case histories. Three case histories of major karstic sinkholes are analyzed to show that man-made structures above a karstic cavity prevent formation sinkhole. When plastic zones reach the structure periphery, the soil-structure system becomes unstable. Prior settlements could be negligible to serve as precursors. Another soil-footing-superstructure (SFSS) model is a 2D geotoy - an exact mathematical solution, used for multiple simulations (about 10,000) of SFSS sensitivity i.e., response to input parameters variations. The sensitivity was rated for each input-output pair [1]. The most interesting findings are the following: 1) SFSS stress state is very sensitive to soil strength parameters c and φ, which are responsible for formation of soil disruption zones (‘plastic zone’) under footing edges. 2) If a structure rests on a homogeneous soil base then it is practically insensitive to soil base compressibility i.e., soil modulus E variations. 3) 3D FEM analysis confirmed that 2D simulations can be used for qualitative SFSS analysis. 4) Geotoys can be used for case histories analysis, risk assessment, training practical intuition, education purposes and international exchange and cooperation

Seismic Behavior of Nailed Soil Massifs

Soil nailing technology can be successfully applied to strengthen natural soil massifs in seismic regions, provided adequate analysis is available. Conventionally, the design of soil nailing is performed iteratively: firstly parameters of nailing and their distribution are assigned, the safety factor of the nailed massif is calculated, if its value is less than 1 then nailing parameters are reassigned, etc. Such “trial and error” approach is laborious and especially so, because different types of ULSs shall be analyzed. The method, discussed in the paper, is based on assumption that the effect of nailing in soil with internal cohesion c=c(x,y) could be simulated by equivalent internal cohesion Δc=Δc(x,y) (deficit) of unreinforced massif. Formulae for calculating nailing parameters are determined on the basis of deficit distribution. A MathCad code has been developed, examples are given. The method can be easily applied to assess seismic stability of nailed soil massifs

Deformations of Existing Buildings, Caused by Construction Activities

Construction of a new building (NB) affects existing adjacent old buildings (OB) during pit excavation, piling, footing and NB erection. Two relevant history cases are described. In the first one, the graphs of OB settlements versus distance from the pit are given for the period of pit excavation and the total settlements for the period of NB erection. The second case gives the family of OB settlement time-related graphs versus distance from the pit, in which these settlements were caused by piling operations