Geotechnical News• December 2019
39
THE GROUT LINE
• State-of-the-art fully instrumented
multi-pump containerized grout
plant technology (Züblin AG)
Looking Ahead
The course organizers are delighted to
announce an extended collaboration
in order to deliver annual (USA –
Europe) course offerings on a consis-
tent international platform. The 41
st
annual course will be held in Phoenix,
Arizona from September 14 – 18,
2020. It is further planned to memo-
rialize the course content by Wiley-
Ernst & Sohn publishing a practical
grouting reference book, having the
title…you guessed it…”Grouting Fun-
damentals & Current Practice”.
Join us in Phoenix, Arizona for
the 41
st
Annual Course:
September 14-18, 2020
For additional information visit
The second news
item is related to the
6
th
International Grouting Conference,
following the 5
th
, 2017 conference
held in Honolulu, HI.
The organizing committee is still at
work on the details, but we already
have the dates:
February 13-16, 2022
at New Orleans Marriott, one week
before the Mardi Gras. Mark your
calendar and prepare your abstract/
papers!
A Combination of Jet Grouting and MPSP Grouting in
Iskar River Cascade Hydropower Plant in Bulgaria
Andrea M. R. Pettinaroli, Mario Ruggiero,
Gabriele Balconi, Massimo Poggio, Riccardo Castellanza
Introduction
The Iskar River Cascade Hydropower
Project is situated north of Sofia,
Bulgaria, and it is composed by nine
plants. Actually five of them have been
built and produce energy. Each plant is
composed of a penstock followed by
the turbine building, a spillway, and an
earth dam that contains the reservoir.
The Iskar river runs in a narrow valley
characterized by diorite or diabase
rocks, with an upper deposit of allu-
vial soil, composed mainly of gravel
and sand.
Each plant required an impervious
curtain under the structures and in
correspondence with the earth dam:
this has been obtained by means of a
jet grouting treatment of the alluvial
coarse soil, and a grouting treatment
with cement
mixtures of the
underlying rock
using the MPSP
technology.
During the
construction of
the structures,
the site has been
shielded from the
river water by a
temporary earth
embankment that has been statically
improved and waterproofed by jet
grouting columns reinforced with steel
tubes; this allowed work to be done
without interruption even in case of
flood of the Iskar River.
The design of the plants
The design of each plant included a
detailed campaign of geotechnical
investigation, and a long term moni-
toring system for the control of the
efficiency of the impervious curtain
and of the stability of the earth dam. In
Fig. 1 the typical plant.
Figure 1: Power plant of Lakatnik.
Figure 2: Geotechnical investigation at the power plant of Lakatnik.
