1639
The device of the bases and foundation in the conditions of weak soil and high
seismic activity of the Republic of Tajikistan
L'appareil des bases et de la fondation dans les conditions de faible sol et la haute activité sismique
de la République du Tadjikistan
Usmanov R.
Geotechnical society of Tajikistan, Dushanbe, Republic of Tajikistan
ABSTRACT: The results of years of research characteristics flooding and water logging areas in the Republic of Tajikistan,
previously folded little moisture loess soils subsidence. Found that the water saturation of the soil contributes to the transition into the
category of weak and high compressibility, a significant reduction in their strength and deformation parameters. The studies will
improve the effectiveness of design and construction of buildings and structures in seismically active areas
.
RÉSUMÉ : Les résultats d'années d'inondation de caractéristiques de recherche et de régions de notant d'eau dans la république du
Tadjikistan, a plié auparavant peu d'affaissement de sols de lœss d'humidité. Constaté que la saturation d'eau du sol contribue à la
transition dans la catégorie de faible et haute compressibilité, une réduction significative de leur force et paramètres de déformation.
Les études amélioreront l'efficacité de design et la construction de bâtiments et de structures dans les régions sismiquement actives.
KEYWORDS: weak water-satureted loess soils, the high-condensed soil pillows, deformations at static and seismic loadings.
1 INTRODUCTION
In many seismically active regions of the Republic of
Tajikistan weak water-saturated soil on which industrial and
civil constructions of different function are erected and operated
are widespread. Researches and operating experience of
constructions on this soil testifies to considerable decrease in
strength and deformation characteristics of soil at seismic
influences and indicates the need of their account at calculation
of the bases. Various methods of artificial improvement of
properties of soil and the pile foundations are applied to
decrease in influence of seismic influences and increase of
seismic stability of constructions.
For a number of years in the country complex laboratory and
field (natural) researches of features of work of the uniform and
artificial bases, and also stuffed piles were carried out at seismic
influences. In field conditions imitation of seismic forces is
made by means of the explosive influences which essence is
that by means of explosion separately set parameters of seismic
forces for the purpose of the solution of specific objectives
receive (Medvedev S. V. 1967, Lekarkin V. K. 2005, Usmanov
R.A. 2009
).
Thus explosive influence only on separate dynamic
characteristics can come nearer to certain types of earthquakes.
The specified method widely is used at the solution of
geotechnical tasks in difficult engineering-geological conditions
of the republic.
2 THE HOMOGENEOUS BASES
The purpose of researches was studying of influence of
seismic (explosive) impacts on decrease in bearing ability and
increase in compressibility of the uniform bases put by weak
water-saturated soil. Field researches were conducted on the
experimental site put by weak water-saturated loess soil more
than 16,0 m thick, a way of a simultaneous loading of two
round metal rigid stamps by the area A = 1,0 sq. m (d = 1,13 m)
static and seismic (explosive) influences (fig. 1). By results of
static tests of value of calculation resistance of soil made R ≤
100 kPa, and the deformation module - E = 2,7-3,5 MPa (fig. 2).
The analysis of development of layer-by-layer movements of
soil on depth of the basis shows that more than 90% of the
general deformations occur within depth equal to diameter of a
stamp.
Figure 2. The results of static tests by stamps
Figure 3. Development of deformations
on basis depth
Figure 1. Scheme of carrying out static tests:
1- load pulleys; 2- metal platform; 3- metal stamp;
4- weak soil
