FROM FOREIGN EXPERIENCE
NEW
CZECHOSLOVAK
DEVICE
INVESTIGATING
STRENGTH
PERMEABILITY
OF
I. Klement'ev
FOR AND
SOILS and
M.
I. Nikitenko
UDC 624.13t.374/377(437)
A set of devices for determining the strength and p e r m e a b i l i t y c h a r a c t e r i s t i c s of soils has been developed at the S c i e n t i f i c - R e s e a r c h Institute of Engineering Structures (VUIS), Bratistava, Czechoslovakia. The soil specimens a r e loaded either d i r e c t l y by p r e s s u r e w a t e r applied to them or by a force generated by a hydraulic cylinder. The set of devices c o m p r i s e s (see Fig. 1): a controlling device 1 for generating liquid p r e s s u r e , loading f r a m e 2, hydraulic cylinder 3, r e g u l a t o r 4, m e t e r for r e c o r d i n g volume of displaced w a t e r 5, and w a t e r deg a s i f i e r (not shown in photograph). Degasified distilled w a t e r s e r v e s as the liquid pumped to generate the required p r e s s u r e . The m i c r o pump used to deliver the w a t e r is designed to p e r m i t both raising and lowering the p r e s s u r e . The type of pump used is suitable for p r e s s u r e s up to 2.5 MPa, and is capable of delivering the water at rates of up to 750 cm3/h. The height of loading f r a m e 2 adopted depends on the m a s s of the specimen under t e s t . The specimen can be preloaded manually by means of a threaded device 7. T h e r e a f t e r , it is loaded by a hydraulic cylinder 3 fitted with a b e l l - s h a p e d m e m b r a n e which has pumped w a t e r delivered to it. A force of up to 20 kN can be generated in this m a n n e r , a s s o c i a t e d with displacements of up to 50 cm. The magnitude of this force can be v a r i e d by r e g u l a t o r 4, which can maintain individual p a r a m e t e r s at a designated value o r in a c c o r d a n c e with values p r e s e n t e d by the c o n t r o l s y s t e m , e.g., a minicomputer. The m e t e r r e c o r d i n g the volume of displaced water 5 is used mainly in determinations of p e r m e a b i l i t y and for triaxial t e s t s . As it utilizes the principle of l e v e r s of equal length, high a c c u r a c y is achieved. F o r the w a t e r degasifier, use i s m a d e of a Czechoslovak s e r i e s - p r o d u c e d device recently developed, which s e r v e s to r e m o v e gases f r o m the liquid being pumped. The d e g a s i f i e r is used to d e t e r m i n e w a t e r s e e page and for triaxial t e s t s on soils. The set of devices d e s c r i b e d above can be used most effectively for controlled experiments. In this case the p a r a m e t e r s being m e a s u r e d can be dependent on an algorithm of t e s t s , which is p r e s c r i b e d by the control s y s t e m , e.g., a minicomputer.
Fig. 1. General view of set of devices for investigation of soils. T r a n s l a t e d f r o m Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, p. 25, May-June, 1979o
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0038-0741/79/1603- 0156 $07.50 © 1979 Plenum Publishing Corporation
Use of the a b o v e - m e n t i o n e d s y s t e m enables the conditions f o r conducting the t e s t s to be a p p r o x i m a t e d to the actual loading conditions of a soil interacting with the s t r u c t u r a l component involved. In addition, it enables any d e s i r e d p r e s s u r e c o r r e l a t i o n s to be s e t up at the exit and the exit f r o m the soil s p e c i m e n during m e a s u r e m e n t s of p e r m e a b i l i t y , and so to a p p r o x i m a t e the actual conditions o c c u r r i n g during w a t e r s e e p a g e in n a t u r e . M o r e detailed information about this s e t of devices and the p o s s i b i l i t i e s of p r o c u r i n g it can be obtained f r o m the Faculty of B a s e s , Foundations and E n g i n e e r i n g Geology, the B e l o r u s s i a n Polytechnic Institute (65 Leninskii Proutok, Minsk, 220027).
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