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17IMPROVED METHODS OF CALCULATING OF GRAVITY-TYPE STRUCTURES
Khoneliia N.,
Assistant professor Odessa National Maritime University Ukraine, Odessa, Mechnykova str. 34 Fedorova K. Assistant professor Odessa National Maritime University Ukraine, Odessa, Mechnykova str. 34
Abstract
The results of studies of the reactive capacity of the soil base of a gravity-type quay-wall on the basis of the method developed for calculating the "structure - soil base" system are considered. The method proposed allows determining the reactive capacity of the soil base in conditions of mixed stress state model (limit and sublimit stress state of the soil base) under and around of the base of the foundation structure in a wide range of loads of lateral earth pressure. The transformation of limit and sublimit stress state zones of the soil base on the basis of numerical modeling is presented which shows an increase of the sizes of limit stress state and a decrease of the sizes of sublimit stress state.
Keywords: the reactive capacity, gravity-type quay wall, numerical modeling, limit and sublimit stress-strain states, lateral earth pressure, the soil base.
Introduction. Gravity-type quay-walls are the most common type of walls used for harbor berths. Reliability of the soil bases is one of the main factors in the design and the reconstruction of gravity-type quay-walls. Maritime transport development considerate the task of cargo complexes modernization and change their specialization including change of their operating condition. Thus, the studies of the reactive capacity of the soil base of a gravity-type quay-wall are importance and up-to-date.
The limit loads produced an effect on gravity-type quay-walls are of interest in the design or reconstruction of mentioned structures. It should be noted that the increase limit loads cause the loss of the reactive capacity of the soil base under the base of the foundation structure. Most often disturbance of stability of the soil base leads to a large settlement, to the rise from under the foundation and to the displacement of the structure. Significant displacement is dangerous for most of the aforementioned structures. Therefore, it is important to determine the maximum possible load on the soil base that won't disturb its stability.
Purpose of the study: to present the study's results of the reactive capacity of the soil base of gravity-type quay-wall on the basis of developed calculation method "structure - soil base" system [1] taking into consideration features work of the structure and soil backfill. The method proposed determines the reactive capacity of the soil base in the conditions of mixed stress state model. The model considers limit and sublimit stress state of the soil base under and around the foundation structure.
Research results. Calculation model of the "structure - soil base" system has been developed and numerical modeling has been performed in a wide range of loads of soil backfill pressure for studying of the system considered.
Occurrence issues of limit state zones of the soil base, determination of limit load causing their formation under the base of the foundation structure and influence of considered factors on the work of the "structure - soil base" system have been discussed earlier by authors: M.V. Malyshev [2], P.I. Yakovlev [3], S.G. Kushner [4].
Currently, methods of calculation of the soil bases which are used in the design of berth structures don't take into consideration the presence and the transformation of the limit and sublimit stress state zones. Experimental studies conducted by Y.K. Zaretsky [5] have shown that the reactive capacity of the soil base depends not only on the strength properties of the soil base but also on the parameters which describe its behavior in sublimit stress state.
The calculation method of the reactive capacity of the soil base has been developed. It is based on the theory of the limit stress state. The method is different from other methods by the presence of two zones of soil stress state (limit and sublimit) in the soil base of the structure and by considering of the friction on the contact of rigid foundation structure and the soil base. The scheme of calculation of the reactive capacity of the soil base is shown in Fig. 1.
The model proposed of the interaction of a gravity-type quay wall with the soil base is based on the following presupposition:
1. The soil base interacting with the base of the foundation structure includes zones of limit and sublimit stress state.
2. The boundary of limit and sublimit stress state zones of the soil base (the width be of the contact zone of the soil base which is in limit stress state) is determined according to recommendations [1] and can be got from the expression
= E - 0.5 • B •(/ + /:/)
e 2 f - r)
(1)
be - the width of the contact zone of the soil base
interacting with the base of the foundation structure in limit stress state;
B - the width of the base of the foundation structure interacting with the soil base;
rmp
J np - the intensity of the friction forces on the contact of the base of the foundation structure and the soil base within the width of limit stress state zone;
f - the intensity of the friction forces on the contact of the base of the structure and the soil base within the width of the sublimit stress state zone;
E - the resultant of lateral earth pressure (depends on an uniformly distributed load of intensity q). It is defined as the vector sum of two components: limit Ee
and sublimit E', according to the recommendations [6] and may be expressed as
E = \e% + E'2 + 2• Ee • £'• cos(5e -5 ')}
/2
(2)
3. Limit component of the reactive capacity of the soil base Ne. It conforms to the force acting within the
width be of limit stress state zone. Sublimit component of the reactive capacity N'. It conforms to the force acting within the width B- be of sublimit stress state zone (see fig. 1).
Fig. 1. The sliding surface and the outlines of limit and sublimit stress state
zones of the soil base
4. The components' deflection angles Ne and N'
and the resultants of reactive pressure of the soil base along the sliding surface from the normal to the boundary of this surface are accepted for limit stress state zone 5e j pe and for sublimit stress state zone accordantly 5 , p . It should be noted that the angle p is determined according to the recommendations [6] and may be expressed in form p' = po + np — po ).
Based on the design scheme (see Fig. 1) it can be obtained followed characteristics:
- the angels 5 and 5e, determine
as
determined from geometrical consideration of the design scheme;
- the angle po conforms to the earth pressure at
rest and can be taken according to the recommendations [7].
5. The resultant of the reactive capacity of the soil base N can be determined for each current deformed state of the structure as the vector sum of two components: limit Ne acting within the wide be and sublimit
N' acting within the wide B- be. In this case, the resultant of the reactive capacity of the soil base N can be expressed by the equation
tg5 = E / G and tg5e = Ee / Ge where Ee, Ge and E j G horizontal and vertical components of the resultants Ne and N accordingly in the range of
limit and sublimit stress state zones;
- the parameter n is depended on the sizes of limit and sublimit stress states zones of the soil base and is
determined by the ratio n = Ve / V where Ve - the
volume of the area of the soil base being in limit stress state; V - volume of whole soil mass interacting with the base of the foundation structure. Ve and V can be
N = \N2e + N2 + 2• Ne • N
• COS(5e -5 )J/2
(3)
6. The cohesive soil characterized by specific cohesion c can be taken into consideration by loading of an uniformly distributed load acting downward on the top surface of the sol backfill. The intensity of the load
within limit stress state ne = c / tgpe and the intensity of the load within sublimit stress state n' = c / tgp as shown in fig. 1.
The resultants of uniformly distributed loads in the
first case Gce and in the second case G'c . It should
considerate the increment of the cohesive pressure An on the boundary of limit and sublimit stress state zones which can be calculated as follows: An = c ■ ctg ).
The balance conditions of limit and sublimit strain stress zones of the soil base are considered consistently
for determination of limit Ne and sublimit N' reactive
capacity of the soil base. In this case, it considers force interaction of the aforementioned zones.
Some results of numerical modeling of the "structure - soil base" system are considered. It should be emphasized that there are two phases of the interaction of gravity-type quay wall and the soil backfill: the phase of structure construction which includes the process of formation of the soil backfill; the phase of operation when an uniformly distributed load q effects on the structure. The paper studies the second phase of the interaction of gravity-type quay wall and the soil back-
fill. In this case, soil backfill lateral pressure will increase depending on the loading and the increase of an uniformly distributed load q.
The increase load q leads to the growth of the reactive capacity of the soil base (due to the appearance and development of limit stress zones in the soil base). This process can be continued while limit reactive ca-parity in the soil base won't be reached. Further increase of the external load may lead to loss of the structure stability due to the exhaustion of the bearing capacity of soil base.
The growth of an uniformly distributed load q leads to the increase of active earth pressure of the soil backfill and to the transformation of the areas of limit and sublimit stress states of the soil base. The transformation leads to the increase of the area of limit stress state and to the decrease of the area of sublimit stress state. An example of the transformation of considered zones as a result of the increase of the load q is given in % 2.
Fig. 2 The transformation of limit and sublimit stress state zones of the soil base: the boundary of sublimit strain stress zone in the case of the achievements of active pressure which leads to
formation of limit strain stress zone 1; 2, 2 '; 3, 3'; 4, 4' - the boundaries of limit and sublimit stress state zone of the soil base as a result of the increase of the load q; 5 - the boundary of the soil mass in case of achievements of limit reactive capacity of the soil base
1
At the time of the transformation of the boundaries of limit stress state of the soil base 1, 2, 3 and 4 fall down remaining parallel due to the constancy of the angle Ve. The boundaries pointed pass through the points of the contact surface of the base of the foundation structure within the width b1, b2, b3 and b4. The boundaries of limit stress state of the soil base 1, 2, 3 and 4 in the area located behind the foundation structure fall down remaining parallel due to the constancy of the angle 45 Ve/2.
The boundaries of limit stress state of the soil base 1, 2, 3 and 4 in the intermediate area (Prandtl zone) fall down due to the constancy of the angle 6e (Be is the angle of the logarithmic spiral of considered area). At the same time the boundaries of sublimit stress state 1 ', 2', 3 'and 4' under the base of the foundation structure
change the slope to the horizon from angle Vl to V
V and V4 as a result of the increase of active pressure
in the range from Ea to EnP.
The boundaries of sublimit stress state 1', 2', 3' and 4' in the area located behind the foundation structure change the slope to the horizon from angle 45°- 91'/2 to 45°- 92'/2; 45°- 93'/2; 45°- 94'/2 in accordance with considered range of active pressure. The boundaries of sublimit stress state 1', 2', 3 'and 4' in the intermediate area change the angle from 01 to 02, 03, 04. Pointed boundaries are drowned by a logarithmic spiral as shown in fig. 2.
It should be noted that the growth of an uniformly distributed load q at the time of the formation of sublimit stress state zones reduces the sizes of sublimit stress state and changes the boundaries outline of the sliding surfaces. This process continues until the width of limit stress state zone won't reach of the value B.
CONCLUSIONS
The most important factor affecting on the assessment of the reactive capacity of the soil bases of gravity-type quay walls and on the determination of work of the "structure- soil base" system is lateral soil pressure. Thus, the study of the reactive capacity of the soil base on the basis of the calculation model proposed of the "structure-soil base" system is an important task. The findings of studies can be used in the design and the construction of considered structures and so for the analysis of the technical condition of the operation structures including rigid retaining walls.
References
1. Khoneliia N.N., Dolinskaia N.B. The main directions of development of methods for calculating of the bearing capacity of the soil bases of port waterfront structures. Collection of Scientific Works. Building constructions. Kyiv: State Research Institute of Building Structures, 2014, no.2(75), pp. 404 - 411 [Published in Ukrainian].
2. Malyshev M.V., Savenkov A.S., Elizarov S.A. Development of areas of limit state in the soil base of a
square stamp. Bases, Foundations and Soil Mechanics. NIIOSP, 1991, pp. 15-17 [Published in Russian].
3. Iakovlev P.I. Results of experimental studies of the interaction of waterfront structures with soil. Collection of Scientific Works. Vladivostok, 1989, pp. 134 - 140 [Published in Russian].
4. Kushner S.G. Calculations of the bases of structures with using of limit stress state theory. Bases, Foundations and Soil Mechanics. NIIOSP, 2002, No. 1, pp. 2-8 [Published in Russian].
5. Zaretskii Yu. K. Bearing capacity of sandy bases of the foundations. Bases, Foundations and Soil Mechanics. NIIOSP, 2006, no. 3, pp. 2 - 8 [Published in Russian].
6. Khoneliia N.N. Lateral soil pressure on a retaining wall with a stone prism of improved shape. Collection of Scientific Works. Kyiv: State Research Institute of Building Structures, 2004, no. 61, pp. 219-225 [Published in Ukrainian].
7. Iakovlev P.I. Engineering calculation methods of the interaction of waterfront structures with soil on the basis of limit stress state theory. Training manual. Mortekhinformreklama, 1986, 50p. [Published in Russian].
OZONATION AS AN EFFECTIVE DISINFECTION METHOD FOR CHEESE RIPENING
CHAMBERS
Salodkaya K.,
Bachelor student, Grodno State University Trotskaya T.
PhD, Professor, Grodno State University
Abstract
A major advantage of ozonation over traditional thermal and chemical disinfection methods is that it is an effective, modern, and efficient means of dry, low-temperature ripening chamber treatment. The disinfecting effects of ozone on cheese ripening chambers ensure the necessary sanitary and hygienic conditions of air microflora.
Keywords: ozonation, disinfection of cheese ripening chambers, ozone in cheese technology, cheese storage, Penicillium, Cladosporium and Aspergillus molds in cheese production.
Ozonation is a modern and efficient method of dry low-temperature treatment for technological equipment, production premises and raw materials at food industry enterprises. Ozone is able to provide high-efficiency sanitary treatment and to destroy even those microorganisms that are resistant to chlorine, due to its strong disinfectant properties.
Ozone disinfection is simple and cost effective. The simplicity of the method lies in the fact that ozone is generated directly from the air, no additional reagents are required to obtain ozone. Ozone is synthesized from oxygen within a few seconds and quickly destroys microorganisms, 300-3000 times faster than disinfectants, ultraviolet lamps and chlorine-containing chemicals. [1]
Ozonation can be called one of the most cost-effective disinfection methods. For disinfection, only an ozonizer is needed, which will be used repeatedly in the
future. This technology does not require the use of water, consumes less electricity, results are quickly achieved, environment friendly method and does not require any special reagents or other means — all mentioned above shows the economic feasibility of using ozonation.
Ozonation is an eco-friendly disinfection method for both people and the environment, because decomposes into harmless oxygen and water within a short time. After airing, the rooms become absolutely clean and harmless to people. Chemical disinfectants, unlike ozone, do not destroy all bacteria and viruses, not all have sporicidal activity, and the reagent is also able to remain on the surface after treatment.
The dairy industry uses ozone for processing cheeses, specifically for sterilizing cheese ripening chambers. [2]
