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The phenomena of soil liquefience in the bases of
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012081
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AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
1
The phenomena of soil liquefience in the bases of hydraulic
structures
M A Kolosov, K P Morgunov
Admiral Makarov State University of Maritime and Inland Shipping, St. Petersburg,
Russian Federation
E-mail: morgunovkp@gumrf.ru
Abstract. The article presents the results of an analysis of the potential for the phenomenon of
soil liquefaction in the bases of hydrotechnical structures. The authors note that hydraulic
structures are usually built in the valleys of watercourses where the soil structure is highly
conducive to liquefaction processes. These are finely dispersed non-cohesive soils, usually
fine-grained, medium-grained or silty sands, sandy loam. Massifs under pressure hydraulic
structures are usually highly water-saturated. At the moment of liquefaction, the sandy soil,
which was previously stable due to the friction of the particles, becomes a suspension, i.e.
water with soil particles suspended in it, so structures located on such soils sink in this
suspension. The article provides examples of accidents in the hydraulic structures of Russia
caused by the liquefaction phenomena. The authors note that the main directions of protecting
the structures of hydraulic structures from the consequences of liquefaction are to prevent the
possibility of liquefaction and reduce the harmful effects of liquefaction. There are several
methods and ways of reducing the possibility of liquefaction - the creation of an effective
drainage system consisting of vertical drainage piles or vacuum wellpoints in the bases of
structures where there are prerequisites for liquefaction. The paper proposes the construction of
reinforced structures by resting on dense layers of soils below layers liable to liquefaction. It
notes the need to consider the phenomena of soil liquefaction of bases in the normative
literature on the design and operation of hydraulic structures.
1.Introduction
The phenomenon of soil liquefaction is well known in soil mechanics. Peculiarities of construction
and operation of structures erected on soils liable to liquefaction processes are considered in the works
of both domestic [1, 2, 3] and foreign authors [4, 5, 6]. However, we find that this process does not
receive sufficient attention in hydraulic engineering construction and operation of hydraulic structures
(HS).
Hydrotechnical structures - dams, hydroelectric plant buildings, ship culverts (locks, ship lifts) - are
usually massive structures that have a significant impact on the soils where they are located. Much of
the research into the processes involved in the bases of hydraulic structures focuses on the
consolidation of soils [7, 8]. As is known, soil consolidation is the delayed compaction (increase in
density) of a water-saturated soil layer over time, occurring due to the squeezing out of water or the
convergence of soil particles under load. The duration of the consolidation processes of the soils at the
base of the HS depends on the structure of these soils and the consolidation processes can take a
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
2
considerable amount of time. For example, the consolidation of soils at the base of the Gorodets locks
(Volga Basin Administration) lasted about 50 years, at the base of the Volga locks (Volgo-Don) the
consolidation period took about 30 years [7]. As noted in [9], in the presence of clayey soils in the
foundations, settlement of structures can develop throughout the life of the structure.
Liquefaction of soils is a qualitatively different process, the transformation of soils into a fluid state
as a result of a significant change (up to and including destruction) of the soil structure, irrespective of
the cause of this transformation. Such processes develop in non-cohesive soils whose pores are filled
with water. The dynamic action on these soils destroys the structural bonds between the particles and
the saturated soil acquires the properties of a heavy viscous fluid. As a result, earthen structures are
spread and heavy structures located on such soils sink in the liquefied soil. World practice knows
many examples of such accidents and disasters.
In 1912 in Revel (now Tallinn) the head of a breakwater made of ribs suddenly shifted by 2 metres
in totally calm weather and collapsed, sinking deep into the ground. A similar case occurred with the
rowing embankment in the port of Kandalaksha: rowing was installed and soil was backfilled between
the rowing and the shore to form the port area. Suddenly the ground turned into a liquid body that
spilled over a distance of several dozen metres and within two minutes the embankment was
destroyed; the ground took the rows of trees with it and they sank in it. There are also known ground
liquefaction-induced failures during the Niigata (Japan) earthquake in 1964 [10], the Bora Peak in
(USA) in 1983 [11], the Bhai and Ahmedabad in 2001 [12] and the Christchurch (New Zealand) in
February 2011 [13].
An analysis of the location of navigational hydraulic structures in operation in Russia revealed that
a large proportion of them are located on weak non-cohesive soils which are subject to liquefaction
phenomena under the right conditions. However, the current regulatory literature in the Russian
Federation defining the rules for the construction and operation of hydraulic structures does not reflect
the liquefaction processes.
2. Materials and Methods
Studies of liquefaction processes in soils mainly focus on the occurrence of such phenomena under
significant dynamic impact with high frequencies - earthquakes, vibrations and other forceful
influences [14, 15]. It is known that the ability of soil to liquefy, float and lose its strength completely
under the influence of shaking, vibration or other external influences is called thixotropy. But soils can
liquefy not only through vibration. The above mentioned accidents in Tallinn and Kandalaksha
confirm this.
Liquefaction occurs as a result of the breakdown of structural bonds between particles in water-
saturated dispersed soils under different types of stresses. This can cause the soil to lose all or part of
its load-bearing capacity and become fluid as a result of structural failure and movement of the
particles in relation to each other.
The liquefaction process generally consists of three stages: the destruction of the original soil
structure; the transition of the soil into a liquefied state; restoration of the structure and gradual
consolidation of the soil. Water-saturated fine sands, dusty sands and sandy loam are the most
commonly liquefied. The greater the porosity of the ground, the less dynamic stresses will cause
liquefaction. A prerequisite for liquefaction is complete or near complete saturation of the ground with
water [16]. When the ground is dynamically stressed, the pore pressure in the soil increases, which
leads to shear deformation and volumetric deformation. When there is a large amount of water in the
ground, it does not have time to leave the pores it was in, so pore back pressure occurs, which reduces
the shear resistance. Pressure dissipation at the ground surface and settling of particles leads to abrupt
settling of structures.
The strength and stability of
ground structures
depend on the following parameters:
- the angle of internal friction, which characterises the frictional force between the ground particles;
- cohesion, which characterises the resistance of soil particles to all movement and depends on the
structural bonds of the clay particles.
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
3
The angle of internal friction and cohesion together determine the shear resistance of soils. At the
moment of liquefaction, the sandy soil, which was previously stable due to the friction forces of the
particles, becomes a suspension, i.e. water with soil particles suspended in it, so structures located on
such soils sink in this suspension.
Research shows [17] that the natural angle of repose at 13 - 14 % moisture content is the same as in
the respective sands and sandy loam, and that the natural angle of repose decreases sharply with
increasing moisture content, reaching almost zero at 17 - 20 % moisture content. In addition, the
Archimedean weighing force acts on the ground particles, reducing the pressure between the particles
and therefore reducing the friction force. Soaking of the clay and dust particles that bind the coarse
grains also reduces the bonding force between them.
The coagulation structure formation processes occur simultaneously [18]. These phenomena are
typical of "transitional" (from pure sands to clays) soil varieties such as dusty sands, sandy loams and
some light loam varieties and are associated with the destruction under dynamic conditions of both
coagulation and mechanical contacts. Moreover, the specific composition of these soils contributes to
the mutual breakdown of both types of contact. Therefore, such soils in the liquefied state have the
lowest viscosity (lower than that of liquefied clays or sands) and the highest mobility of all dispersed
soils. The clay particles in the soil are the reason for their ability to remain in a liquefied state for a
long time.
After removing the dynamic load, there is a process of gravity compaction of the soil. In this case,
the soil particles tend to settle more densely, and this results in system consolidation.
One of the conditions for liquefaction is the presence of layers of granular particles in softer
materials in the soil column, which is common in many river sediments. Hydraulic structures generally
tend to be located in river valleys and are therefore characterised by this type of soil structure -
alternating layers of sand and loam. The construction of retaining structures - dams, dikes, locks -
creates level gradients in the watercourse (river, canal) channel, supported by the pressure front of the
waterworks, which ensures water saturation of the foundation and creation of filtration flows with
sufficiently high head gradients in them. The impeded outflow of groundwater from beneath structures
in the foundation soils creates conditions for liquefaction.
In some cases, there is incomplete liquefaction of the ground, called partial liquefaction in work
[1], where the overpressure in the ground does not reach the maximum limit value. Some compressive
stresses in the soil skeleton are retained and the ground has some load-bearing capacity.
The occurrence of basement liquefaction phenomena can provide a new perspective on the causes
of landmark accidents and negative trends in Russian hydraulic structures that have occurred in recent
years.
3. Results
Ship lock No. 5 of the Volga-Don Shipping Canal
Sedimentation of the chamber and head sections of the Volga-Don Shipping Canal (VDSC) lock No. 5
that started from the beginning of operation (1952) continued until 2016, reaching over 100 mm, with
the sedimentation of sections IV and V beginning to increase dramatically from 2006, the rate of
sedimentation increased to 10 mm/year, the intensity of sedimentation of other sections to 3.60
mm/year. The total precipitation of Sections IV and V from 2006 to 2016 reached 125 mm. The
increase in the settlement was accompanied by an increase in the horizontal deformation of these
sections, which differed markedly from that of the rest of the lock chamber. External signs of
deformation of the lock chamber foundation manifested in the form of settling cracks forming along
the chamber walls in the backfill. In April 2005, a griffin formed in the left-hand drainage basin with
quite an intense outflow of water and the formation of a soaking zone.
Based on the adopted safety criteria, the condition of the lock chamber was deemed to be pre-
emergency.
A set of research works in 2008, 2019 - 2020 revealed significant decompaction of the lock
chamber foundation soils, especially in the area of sections IV and V. Most of the chamber floor is cut
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
4
into the light water-saturated sandy loam of the Lower Bakinsky horizon, which is similar in
composition to dusty fine-grained sands. Fine sands with a particle size of up to 0.1 mm make up the
bulk of the soil almost all the way down to the bottom of the chamber (up to the clay buttress - 12 m).
The percentage of these sands in the samples is between 85-95%.
The water level in the ground of the lock is set at or above the downstream level, the bottom of the
chamber is significantly below this level, the ground below the chamber is constantly saturated with
water with significant head gradients (the head at the hydroelectric station is 9.5 m). The porosity
coefficients for all soil types (coarse, medium, fine and dusty sands) are determined by surveys as e >
0.8 p.u., which corresponds to a friable condition.
Therefore, the base of the lock chamber creates conditions for liquefaction of the soils, which
causes significant continuous settlement of the structure.
Ship lock No. 2 on the Volga-Baltic Waterway
The current final technical status of the Volga-Baltic Waterway's shipping lock No. 2 is assessed as
limited operational capability with a reduced level of safety. A major factor reducing the technical
condition and safety level of the structure is the occurrence and development of a crack at the top edge
of the left abutment and in the left lower head emptying gallery.
The problems that led to the crack in the concrete structure of the left abutment of the lower head
were already evident in the construction phase of the lock. The excavation of the lower head
excavation took place in waterlogged interbedded soft soil variations in the presence of pressurised
and unconfined aquifers. Excavation work under these conditions required special dewatering,
drainage and the selection of appropriate excavation patterns. It was not possible to reduce the
underbalanced surface below the bottom mark by deep-draining wells. The over-moistened soil lost its
adhesion under slight dynamic influences and turns into a floating mass, and leads to the suspension of
the basement preparation works. The executive survey of the excavation of the lower head on
01.06.1956 indicated the presence of liquefied base soil below the level of the excavation bottom up to
2.0 m. An area of liquefied soil has spread below the base of the lower head with a transition to the
adjacent section of cell no. 13.
To lower the level of the depression surface, it was decided to delineate the concrete preparation of
the lower head with wellpoints plants; only after these measures the groundwater level in the middle
part of the excavation was lowered. In addition, we had to install a collector with needles every 0.6 m
in the middle of the excavation of the lower head, only then the level in the middle part dropped 1 m
below the bottom of the excavation, which made it possible to start the concrete preparation work.
The base of the lock head was a clay packet of rocks underlain by sand. During construction, the
loamy soils uncovered at the base elevations of the bottom head of the lock were completely replaced
by sandy soils due to their low thickness and possible change of properties in the open trench. The
creation of the pressure front of the hydroelectric installation, the Belousovsky reservoir and the rise of
the groundwater level in the lock area resulted in the formation of seepage flow in the base soils from
the upstream to the downstream and from the upstream to the Vytegra river bed.
Filtration of fine clay particles from the base of the lower head, as well as suffosion of fine
fractions from the sandy soils began during the operation of the hydroelectric installation, which,
judging by the comparative analysis of the survey data up to 2020, continues. In addition to the
seepage flow, the operation of the lock (filling and emptying of the lock chamber, operation of the
working gate mechanisms) also had a dynamic effect on the characteristics of the soils. This created a
decompacted soil layer in the basement rock roof of the lower head.
As noted above, liquefaction of soils is caused by the following factors: the fine fractional
composition of soils, their high porosity and complete or close to complete saturation of the soil with
water.
Research showed that the content of particles smaller than 0.25 mm for the different layers of the
base soil of the lower head of lock no. 2 ranged from 93.3 % to 97.3 %. The porosity of the soils is
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
5
between 34.77 % and 41.04 %. The soils are fully water saturated as the downstream level is above the
base of the downstream head.
The process of weighting fine-grained soil particles occurs when the soil mass is saturated with
water. The "floating" soil particles reduce their gravitational properties by decreasing the force of
friction between them. The angle of internal friction at a natural humidity of 12.7 % is 31.5°; at a
humidity of 37.47 %, when all the pores in the ground are filled with water, the angle of internal
friction loses its value. There is almost no adhesion between the "floating" particles, the water-
saturated fine-grained soil turns into a "heavy" liquid.
This led to uneven settling of the left and right abutments of the lower head, with the abutment
settlement vectors pointing in different directions: the left abutment to the south-east; the right
abutment to the north-west. This inconsistent operation of the left abutment and the bottom of the
downstream end of lock No.2 resulted in a crack in the concrete. As the processes in the base soils
have not stopped, the crack in the concrete also continues to develop.
Moscow Canal flood-breaking dam between navigation locks No. 7 and No. 8
On 10 January 2019, the slope of the Moscow Canal embankment between shipping locks Nos. 7 and
8 swept away and liquefied soil started flowing into the Volokolamsk Highway. The official cause of
the accident was the inflow of water from the canal under the loam screen along the break between the
sheet pile and the tunnel, with further loam decompaction on the western dyke and the creation of a
failure on the outer slope. The reason is the poor quality of the construction and installation work.
In our opinion, the main cause of the accident was the liquefaction of the sandy soil in the tunnel
cavity structures. The dyke enclosing the canal consists of an impervious loam screen and a retaining
sand prism, and there is no drainage for filtered water. Water entering the sand prism from the channel
through the contact joint between the tunnel cover and the screen filled its entire volume. The absence
of contour drainage between the tunnel cover slab and the sand embankment contributed to the
complete water saturation of the prism, i.e. there was no good drainage (diversion of water) from the
dam. During the winter, the slope of the dyke with the plant soil and grass froze, stopping the outflow
of water from the prism and its evaporation. The ground "floated" when the traction forces exceeded
the thresholds.
Beloporozhskaya MHPP-2 unpaved dam
On March 22, 2020, there was a 7.1 to 20.5 m wide break in the crest at the base of the
Beloporozhskaya MHPP-2 channel earth dam (Kem River, Republic of Karelia). Part of the
downstream bank is destroyed and the ditch is filled with water. According to the experts' conclusions,
the breach was caused by an incorrect assessment of seepage strength during the geotechnical survey,
improper selection of materials and thickness of backflow preventers to the drainage prism. However,
after considering the experts' recommendations, when the reservoir was re-filled on 24 October 2020,
a breach occurred again in the left bank section of the earthen dam.
Soil liquefaction processes are also responsible for the breach of the Beloporozhskaya HPP-2
groundwater dam. The stability of the dam was calculated from the physical and mechanical properties
of the soil according to the current design standards. The seepage coefficient adopted in the design
ensures the seepage strength and stability of the structure when the dam body is backfilled with
moraine soils. The weir body does not have any impervious elements and the weir body is drained by
means of volumetric stone prisms located in the upstream and downstream reaches. However, the
filtration coefficient of moraine soils including fine sand and dust particles has a value of 0.005 -
0.0003 m/day. At these values, drainage is ineffective, resulting in water saturation of the earthen soil.
In addition, the drainage capacity is reduced if the drainage prisms are not properly executed (clogging
with other soils). The water-saturated soil of a dam acquires the properties of a "heavy" liquid.
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
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4. Discussion
To prevent the occurrence of zones of liquefaction of unbound soils dangerous to the stability, strength
and integrity of hydraulic structures, it is possible to propose several measures and structures. The
main areas of structural protection against liquefaction and its effects can be divided into two types:
- preventing the possibility of liquefaction;
- reducing the harmful effects of liquefaction.
Preventing the possibility of liquefaction
The hydraulic structures include large areas of unbound fine-grained soils at the base. It is therefore
effective to prevent liquefaction by compacting, consolidating soils at the base of structures.
1. One method known in practice for compacting fine-grained soils is drainage by diverting water
from the ground. In the Elbe floodplain in Germany, for example, Bauer prepared the base for an
airfield runway on muddy soils using vertical drains. The paper pipes were buried for 10 - 12 m by
paper tape indentation at 1.5 m intervals (Fig. 1, a).
Figure 1. Using paper pipes for drainage:
a - scheme of the arrangement of drenches;
b - scheme of seepage and compaction of the ground mass
When in the wet ground, the paper tape, saturated with moisture, straightened out and became
circular in cross-section. A filtration gradient was formed on the surrounding saturated ground and the
ground gave up water to the paper tube. Around the pipe, there was a zone (column) of dewatered
compacted soil (Fig. 1, b). This principle of capillary movement of groundwater towards the drainage
pipe is widely used in dewatering practice.
2. It is known to increase the gradient for water extraction by means of
vacuum
wellpoints [19].
The
vacuum
wellpoint sinks to a depth of 25 m and is vacuumed in soils with a low filtration
coefficient (K
f
less than 0.5 m/day). Such soils include fine-grained dusty and clayey soils. The
vacuum dewatering unit consists of a 4K-8 centrifugal pump and a GV-5c water jet pump. At a
sinking depth of wellponints of 8.5 m, the capacity of the plant is 40 m
3
/hour. Similar vacuum
dewatering systems were used in the construction of the Volga-Kama cascade of hydroschemes.
3. Since the thickness of the saturated soils is usually of the order of 8 - 15 m (e.g. at the Volgo-
Balt No. 2 and Volgo-Don No. 5 locks), it is also advisable to install vertical drainage. Drainage
includes a drainage column in the form of a perforated pipe, with the interior filled by a material that
absorbs groundwater. Two options are possible: a single-use or multiuse column.
The single use involves the construction of a hollow column in the ground (Fig. 2), which creates a
pressure differential between the water in the surrounding ground and the cavity inside the column.
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
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Figure 2. Diagram of the single-use operation of a depth drain:
a - plan; b - vertical section
1 - perforated pipe; 2 - water outflow boundaries into the pipe (drainage influence zone) 3 - porous
filler;
This difference causes the filtered water to move from the surrounding unbound soil mass into the
column cavity. Once the column is filled with water, the inflow of water from the soil stops, but a zone
of compacted soil with low water content is formed around the culvert - a zone of accelerated
consolidation. It is possible to fill the inside of the pipe with absorbent material: mineral wool, wood
fibre wool, etc. The purpose of this filling is to prevent the inner cavity of the drainage pipe from
being filled with fine-grained sediment.
Instead of completely filling the inner cavity with moisture-absorbing material, it is possible to use
internally lined pipes, with the porous filler material arranged as a layer on the inner surface of the
perforated pipe (Figure 3).
Reusable vertical drainage involves drawing filtered water from the surrounding soil mass into the
drainage pipe and pumping it out periodically. The most reliable design in this case is the twin-
cylinder tube, consisting of two co-axial perforated cylinders (Figure 4). It is necessary to pump the
water out of the inner cylinder as it fills up. The most convenient way to do this is to use vacuum
devices.
Figure
3.
Drainage pipe:
1 - perforated drainage shell; 2 - porous
material lining; 3 - collecting cavity for filtered
water
Fig
ure
4.
Cross section of a drainage pipe
with water pumped out:
1 - outer perforated cylinder; 2 - porous
filler (filter); 3 - inner perforated cylinder; 4 -
inner cylinder mounting (fixation) ribs
Such drainage devices should preferably cover the entire area under the structure, built up of
liquefiable soils, so that the zones of influence of the drains overlap. But often the installation of such
a drainage grid beneath the foundation is technically problematic, accessing it, much less drilling holes
for vertical drainage is very difficult, and sometimes simply impossible. However, usually the pressure
of massive hydraulic structures creates a very significant load on the base so the most dangerous areas
with regard to liquefaction potential are the unloaded peripheral areas of the structure, within which it
makes sense to organise dewatering and consolidation of the subsoil.
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
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In earthen dams, to prevent liquefaction, it is advisable to install drainage dikes or seals on the
underwater part of the slopes and where the underbalance curve is close to the downstream slope
surface. It is possible to use geotextiles, geogrids or rock fill as filter bedding.
Reducing the harmful effects of liquefaction
As noted above, a condition for liquefaction is the presence of a layer (mass) of fine-grained unbound
water saturated soils directly beneath the base of the hydraulic structure. However, the characteristics
of the substrate often make it possible to propose ways of partially or fully supporting the concrete
mass of the structure on layers of soil with a higher load-bearing capacity below the fine-grained
differences. As a rule, the depths from 10 to 20 m from the base of the structures have more dense
layers - clay, dense sands, etc.
It is possible to install a pile-deck to transfer the load from the concrete structures of the structure
to the stronger subsoil. A scheme of such a pile cap that can be proposed to strengthen the lower
downstream end of the Volga-Baltic Waterway lock No. 2 is shown in Figure 5. It includes 6 piles that
are driven along the periphery of the structure. The pile structure must rely on dense soils and transfer
the load from the concrete mass of the structure to them. The transfer of loads requires a special
mating unit (Fig. 6).
Figure
5.
Schematic diagram of the piling
arrangement at the lower head of navigable lock
No. 2 of the VBWW:
1 - lower downstream end of a lock; 2 - bored
piles; 3 –
breakstone
piles
Fig
ure
6
. Scheme of the interface node:
1 - pile tube; 2 - pile reinforcement frame; 3 -
anchors; 4 - concrete head structure
There are two pile variants suitable for waterborne erection conditions:
- bored piles;
- breakstone piles.
The design of these piles allows them to be built both from dry land and from the water. Drilling
piles after laying the concrete mixture assume the extraction of the pipe. Both concrete and breakstone
piles allow an increase in bearing capacity due to the friction between the pile and the surrounding
sand mass. Using breakstone piles can increase the number of piles from six to ten by installing them
in the junction area of the abutment with the flood bed.
To transfer the load from the foundations to the heads of the breakstone piles, it is necessary to
install a single concrete beam (foundation) at the heads of all piles, adjacent to the concrete bottom of
the structure (Fig. 7). The connection can be made using a steel beam fixed with anchors to the face of
the base of the structure.
AEGIS 2021
IOP Conf. Series: Earth and Environmental Science 868 (2021) 012081
IOP Publishing
doi:10.1088/1755-1315/868/1/012081
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Figure 7. Scheme for supporting the structure on breakstone piles:
1 – breakstone pile; 2 - reinforced concrete beam; 3 - anchor in beam; 4 - anchor in concrete base;
5 - steel beam; 6 - temporary excavation for installation work
We recommend the following characteristics for breakstone piles:
- pile depth is up to 12 m;
- pile diameter is 0.8 m;
- сrushed stone in fractions is 20 - 30 mm;
- anchor rods in flood bed d = 70 mm, length 0.8 m;
- anchor spacing is 1.0 m.
5. Conclusions
Thus, we should note that the phenomenon of soil liquefaction in bases is very often the cause of non-
design displacement and deformation of hydraulic structures. The presence of unbound fine-grained
soils at the base of structures, usually located in the valleys of watercourses, contributes to the
liquefaction of soils. After the construction of the retaining structures and the creation of the pressure
front of the waterworks, the base soils are saturated with seepage water with significant head
gradients. In the absence or difficulty of drainage from the soil masses, liquefaction conditions form in
the soil masses.
It is important to take these phenomena into account both at the design stage and during the operation
of hydraulic structures. The analysis has demonstrated that failure to consider the risk of liquefaction
leads to the disruption of structures and even to accidents.
In addition, considering the importance of hydraulic structures and the danger of severe consequences
of accidents on them, it is necessary to include the possibility of the phenomenon of liquefaction of
soils in the regulatory literature.
References
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[2] Voznesensky E A, Kovalenko V G, Kushnareva E S, Funikova V V 2005 Soil liquefaction
under cyclic loads (Moscow: Publishing house of Moscow State University)
[3] Boldyrev G G, Idrisov I H Assessment of the potential of soils for liquefaction Retrieved from:
https://www.geoinfo.ru/product/ocenka-potenciala-gruntov-k-razzhizheniyu
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