3138
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
e) Fixing of soil by way of silicification with activization of
soil by carbon dioxide. Advantages – use of the simple
equipment, high quality of fixing, possibility of fixing of soil in
the basis of the emergency and deformed buildings.
Shortcomings – very high cost and therefore, it is generally
applied to strengthening of soil in the basis of the deformed
buildings and constructions.
f) The device of the pile bases from lovering piles.
Advantages – technological effectiveness, use of the high-
performance equipment, ensuring appropriate quality.
Shortcomings – difficulties at immersion of piles in soil of the
firm and semi-firm consistence, limited application in the
conditions of dense building, cost increase at increase in
thickness of a collapsing layer of earth and removal of places of
production of piles.
All given methods of preparation of the bases and the device
of the bases were investigated on joint action of static and
seismic influences by intensity of 8-9 points on the basis of
which the relevant normative documents on technology of the
device and a calculation procedure were made. However the
know-how showed on possibility of development of uneven
deformations and violation of operational suitability of
buildings and the constructions erected on the specified artificial
bases. Use of these methods expediently and effectively in the
conditions of collapsing soil I of type, and on collapsing soil II
of type – in combination with deep methods of consolidation
and fixing.
After the 80th years design and construction 9-12 floor and
more buildings in this connection researches were conducted
began and the following methods of deep consolidation of soil
and a design of the pile bases are recommended for practical
application:
a) Consolidation by preliminary soaking. Advantages –
simplicity and low cost. Shortcomings – application restriction
in the conditions of dense building, long terms of consolidation,
need for large volume of water, need of the device of no
filtration veils in the conditions of dense building.
b) The accelerated consolidation by preliminary soaking
with application of drainage wells. Advantages – considerable
reduction of terms of consolidation of soil, rather low cost.
Shortcomings - are similar to point “a”.
c) The accelerated consolidation by preliminary soaking in
combination with deep explosions. Advantages – improvement
of quality of consolidation and decrease in risk of development
of seismic deformations. Shortcomings – are similar to point
“a”.
d) Reinforcing of collapsing thickness by soil piles,
including high-strength materials. Advantages – simplicity of
production, use of the simple equipment, use of a local material,
rather low cost. Shortcomings - application restriction in the
conditions of dense building, fast wear of the equipment.
Note: at consolidation of soil on points “a”, “b”, “c” and “d”
in the top part of the basis the buffer non condensed layer 3-5 m
thick (h
f
) which needs to be condensed further with heavy
tampers is formed or to replace with the condensed soil pillow.
e) The device of the bored piles with a diameter from 0,5 to
1,2 m cutting all collapsing thickness. Advantages – possibility
of the device in various conditions with use of the modern
equipment. Shortcomings – use of the expensive equipment,
complexity of quality control of works, need of carrying out
expensive static tests of piles, rather high cost.
f) The device of the combined pile bases when in advance
drilled well the pile of factory production is established, and a
cavity of a well is filled with cement and sand solution.
Advantages – simplicity of the device and use of the simple
equipment, control and improvement of quality of the device of
the pile bases, decrease in their cost. Shortcomings – restriction
of possibility of application and cost increase at increase in
length and distances of transportation of piles.
All above-mentioned methods were investigated on joint
action of static and seismic influences by intensity of 8-9 points
on the basis of which the relevant normative documents on
technology of the device and a calculation procedure were
made. Researches and operating experience testifies to
opportunity and expediency of their application at the device of
the bases and the foundations of high-rise buildings. In the
Figure 1. Methods of the device of the bases and the foundations on loess collapsing soil I of type:
1- loess collapsing soil; 2- non collapsing soil; 3- condensed soil pillow; 4- charges of explosive; 5- driven piles; 6- injektor for chemical fixing
of soil; 7- fixed soil; 8- base in a tamping ditch; 9- condensed zone; 10- tamping rubble
