Shore protection methods - abstract. Scientific electronic library What is a thrust beam in bank protection works

Bank protection works- a set of measures to protect the banks from the dynamic and static destructive effects of water (more precisely, erosion of the channel and banks of water bodies).

Bank protection can be divided into capital and decorative. Both the first and the second carry with it a reduction in damage to the coastal strip.

Capital bank protection associated with the use special technologies and materials that guarantee maximum effect in the protection of the coastal zone. This is the use of hydraulic grades of concrete, gabions, sheet piles, special volumetric reinforced concrete structures. It is also possible to build up the coastal territory by backfilling with soil and hydraulic fill. These methods have long been proven and reliable.

decorative coast strengthening suitable for those for whom, in addition to practical properties, bank protection structures should be aesthetically pleasing. In this case, natural durable materials- natural stone and larch. Before decorating the coastal zone with a stone, it is necessary to provide a limiting support, otherwise the stone will inevitably slide into the channel.

Natural stone on the shore, whether it is a densely packed boulder or dumped river pebbles, does not prevent soil contact with water, but practically reduces the destructive effect of the wave to zero. It is important when using this technology not to miscalculate with seasonal and daily changes in the water level. The water's edge must always rest against bank protection structure. Bank protection works using natural stone are often used for strengthening areas of short duration, as this is the fastest and most inexpensive way.

The specialists of the Hydrostroy company professionally perform bank protection on various technologies. Construction of coastal protection structures of any degree of complexity, in all types of water areas.

Bank protection works- an important and responsible event, which, alas, is often started in a very neglected situation - when the coast has already been destroyed, and landslides threaten nearby buildings. Lack of attention to the problem bank protection can lead to catastrophic consequences. Therefore, if you are the owner of real estate bordering water bodies, we advise you to take a responsible attitude to the condition of the shoreline of the reservoir.

Carried out by specialists of the Gidrostroy company bank protection is carried out according to a pre-prepared project, taking into account all necessary requirements and technological features hydrotechnical construction.

The protection of the coastal territory from erosion is carried out by bank protection structures, which can be made in the form of reinforcement clothes of one type or another, laid on a properly planned slope of the coast or in the form of embankment walls.

A bank protection structure of any type must be stable, durable and, no less important, simple in execution. For bank protection structures, it is desirable to use local Construction Materials which can significantly reduce the cost of their construction.

Slope bank protection can be completed faster and at a much lower cost than the construction of embankment walls. However, bank protection structures of this type cannot always be applied. It must be borne in mind that if the river bank to be strengthened is high enough and complicated by weak rocks, then to ensure the stability of the slope, it will be necessary to allocate a strip of territory of considerable width (for example, with a bank height of 15 m above water level and an average slope of 1: 3, the lost strip of territory will be 45 m). It is not always possible to refuse to use such a significant strip of coastal territory with a limited size of the construction site.

Slope strengthening of the shore is also not possible; it can be used if it is necessary to use the shoreline for mooring ships and organizing loading and unloading operations.

When improving the coastal strip within locality can be used as slopebank protection structures, and embankment walls, depending on the architectural and planning solution of the coastline.

When carrying out bank protection works in the zone of green spaces, combined two-tier bank protection structures are used, consisting of a low retaining wall flooded by flood waters and a slope fixed with sod cover and shrub vegetation. Embankments of this type, in addition to their main purpose as bank protection structures, can also be used to organize recreation for the population.

The complex of city embankments, in addition to bank protection structures, includes special devices in the form of descents - moorings, stairs, etc. The walls of city embankments are covered withsidewalk level with cornice stone and fenced with gratings or parapets.

When designing bank protection structures of a slope type, two main issues must be resolved: the choice of a transverse profile and the type of slope support.

The main parameters of the slope are the height, which is determined by the difference between the marks of the edge of the bank and the bottom of the river, the inception - the length of the horizontal projection of the slope line and the slope, which expresses the ratio of the height of the slope to its inception.

In the practice of bank protection works, single slopes (the slope is equal to its height), one and a half, double and triple, i.e. slopes with slope angles equal to 45 °, 34 °, 27 ° and 18 °, respectively, have the greatest use.

The choice of slope angle is made on the basis of the study physical and mechanical properties soils that make up the coastal area.

For interception surface water flowing to the slope on the coastal territory, it is necessary to arrange an upland ditch, and to drain precipitation falling directly onto the slope of the coast within the berms, ditches should be provided that divert water along the slope, and then dump them along concrete trays into the river.

The design of slope protection, as a rule, is carried out in two stages - an extended design assignment and working drawings.

Based on field survey data, topographic and geodetic surveys of the coastal area, the study of the geotechnical properties of soils that make up the coastal strip, and materials that illuminate the hydrological and hydrogeological characteristics of the area of ​​bank protection, reasonable decisions should be made on the boundaries of the coastal strip to be strengthened in the design assignment. , on the magnitude of the slopes of the reinforcedcoast,ensuring its stability, the need to install berms according to the height of the slope, as well as decisions on the choice of type of fastening separate zones slope (underwater, flooded, non-flooded) and adjacent to the spit section of the bottom of the reservoir.

In addition to these basic decisions, measures should be worked out to streamline the removal of surface water from the adjacent territory and from the surface of the slope itself, as well as proposals for organizing work in terms of cutting and leveling the slope, supplying and laying materials into the slope cover to be strengthened, etc.

In the working drawings, the design of the fastening of the coastal slope is developed in detail. In the case of a slope fastening device with reinforced concrete slabs, the dimensions of the slabs, their reinforcement, the concrete grade, the arrangement and filling of longitudinal and transverse seams, the preparation device for concrete slabs, etc. are established, and the specifications of the necessary materials are also drawn up.

Wave walls.

Such walls differ in functions and operating conditions depending on their location in protected (port) water areas or on open coasts.

Port vertical walls. In addition to coastal protection, they often serve as moorings for small ships. Working in conditions of relatively small waves (h = 1.0–1.5 m), they are relatively simple in design.

Gravity walls are made, as a rule, from the masonry of rubble-concrete massifs with a stone prism and a crushed stone counterfilter (Fig.), sheet pile walls - in the form of an anchored bolter (Fig.). Common disadvantage of these structures is their ability to reflect waves, which leads to the formation of crowds in the port water area.

a - port gravity from concrete massifs; b - the same, sheet pile with an unloading rear prism; c - off-port without a beach (berms); d - the same, with a beach area; 1 - arrays; 2 - fastening the slope with a cobblestone; 3 - anchor rod; 4 - sheet pile wall.

Off-port seawalls work in conditions of storm waves in open areas of the coast. They are much more complex and varied in structure. In order to mitigate wave impacts and reduce the height of splashes, as well as to throw masses of water from the protected coast or the construction of the front face of the walls, a complex curvilinear shape is often given, which is developed as a result of preliminary laboratory research and learning from operating experience of existing facilities. The walls are subjected to intense abrasive action of sand and gravel during storm waves, so their front faces are covered with an appropriate anti-abrasive lining. The intensity of wave action largely depends on the presence or absence of a beach strip, berm or other protective zone in front of the construction.

Walls without a beach (berms) are subjected to especially strong wave shocks, accompanied by high surges, high scouring velocities and intense abrasion particulate matter. They are erected with small disturbances. To protect against underwashing to increase stability, the berms are either buried in the ground, or supported by a powerful resistant array, or equipped with a tooth (Fig.).

The walls with the beach zone (Fig.) are significantly less affected by the waves that extinguish part of their kinetic energy and the protective beach zone. With a sufficient width of the beach, such walls are affected by waves only during strong storms.

Walls with a protective berm are erected in the absence of a beach area. The berm weakens the impact of the wave on the wall, but does not reduce the abrasive action of solid particles, since the speed and strength of the wave flow under these conditions can increase noticeably.

A wall with a coastal barrier experiences softened wave impacts and reduced flow effects. Structurally, the coastal barrier is usually made in the form of a massive outline.

All types of wave-breaking walls experience, in addition to wave loads and impacts, the expansion pressure of the soil from the shore.

Slope bank protection structures and fortifications differ among themselves, first of all, in the design of the protective layer (clothing) of the slope, made of stone, concrete slabs or arrays various kinds synthetic materials etc.

Rock-filled sloping structures are the simplest in terms of arrangement. They represent an aligned inclined or stepped two-layer ( upper layer from stone weighing 0.75 - 100 kg, lower - 30 kg) stone throw with a thickness of about 1, underlain by a counterfilter of crushed stone or gravel (Fig.) on open coasts, the mass of stone, the number of layers and the thickness of the throw can increase noticeably.

Facing slopes with single or double cobblestone, clinker or cobbled (hewn stones) paving on gravel and crushed stone preparation (Fig.) is more difficult to manufacture. Perform its flat, broken and curvilinear outlines of the cross section. Due to the high labor intensity, cladding is rarely used at present.

Slope covers come in a variety of options constructive solutions(fig.): precast concrete or flat reinforced concrete or stepped slabs, asphalt concrete pavements, protective coverings from stone laying with filling of gaps with mortar, shaped blocks, etc. To improve the wave-damping qualities of the coating, its surface is often made with artificial roughness in the form of separate protrusions, steps, etc.

Massive masonry is also quite widespread in sloping bank protection structures, both from arrays correct form, and shaped blocks. It is usually placed on a stone prism with a gravel-crushed stone counterfilter; can form both flat and stepped slope shapes.

Massive sketch, usually two-layer, requires greater thickness The protective layer, however, having a large porosity and, in the case of shaped blocks, increased hooking and not reacting to uneven precipitation, is a very reliable structure with high wave-damping qualities. The consumption of concrete per unit length of a structure from a massive outline can be significantly reduced, and the preparation over the outline can be significantly simplified and cheaper when using special shaped blocks (Fig.).

Combined sloping structures consist of separate parts structures discussed above. The relatively complex technology of erecting these structures is sometimes justified by the overall final indicators of the technical and economic feasibility of their construction.

Bunes, spurs, traverses. The effectiveness of the nano-retaining action of the bun depends, first of all, on the profile (contour) of the structure.

The profile of the groin on the shores with pebble sediments should overlap with its contours the equilibrium profile of the stable formation of alluvial material, which is always deposited on the windward (upper) side of the groin. Such a structure is called a full profile buna (Fig.). If the contour of the groin does not overlap the equilibrium profile of the beach in height (low buoy) or length (short groin), then such a beach is not preserved, the alluvial material is driven through the section that is not blocked by the groin. Under conditions of a sandy coast, sediments are deposited not only from the windward (upstream) side of the buna, but mainly in zones with low velocities along the coastal currents from its leeward (downstream) side. According to their structure, the groins can be gravity, pile and combined.

Gravity groins and spurs can be in the cross section of the slope profile: rock-throw, from massive riprap (from ordinary or shaped blocks), from local materials; vertical profile: from massive large-block masonry (regular or shaped), from giant arrays, etc.

Pile piles can be the simplest single-row construction - from wooden or reinforced concrete piles or metal pipes etc.; two-row - filled with sand, gravel, crushed stone, stone; a complex prefabricated pile-wall - with spans made of reinforced concrete beams, shields and other elements; combined - gravity and pile.

Underwater shore-protecting breakwaters delay and store alluvial material in the space between the breakwater and the shore, which is thrown by storm waves from the sea into a fenced protected water area.

Underwater breakwaters: a - from concrete massifs with a front inclined edge (ordinary gravity); b - fixed by columns - shells; c - two-course (two-tier); g - lightweight design; 1 - berm arrays; 2 - piles.

The effectiveness of the breakwater largely depends on the level of its crest. When the crest is above water, the alluvial material is thrown over the crest with low intensity. If the ridge is set too low, previously deposited beach material, especially sand, can be stolen. In construction practice, gravity and slop underwater breakwaters are most often encountered.

The combined construction of a bun with breakwaters is called traverses.

Gravity structures can be of several types. Masonry from massifs weighing up to 100 tons with a front inclined edge is the most common design in domestic practice (Fig.) On dense bedrock, massifs can be installed directly on the bottom, previously leveled by divers. With eroded soils, they are located on a bed of stone weighing up to 100 kg with a pebble-crushed stone counterfilter with a thickness of about 1 and 0.5 m, respectively.

The berm of the structure, if necessary, is immersed in berm arrays or slabs. To increase stability, arrays are sometimes fixed with piles (Fig.). At considerable depths, the masonry can be two-tiered (Fig.). Thin-walled reinforced concrete structures(Fig.) are used less often.

Throw underwater breakwaters, which are more common in foreign practice, usually consist of a stone core covered with massifs, shaped blocks or slabs.

To protect the shoreline of reservoirs and streams, as well as berths and other hydraulic structures in ports and coastal timber warehouses from the effects of currents, waves, ice and other natural factors shore protection structures are being erected.

Manifold artificial measures used to protect the coast, can be reduced to two fundamentally various methods- active and passive. Bank protection structures, capable of retaining and accumulating sediments due to changes in the hydraulic structure of the flow, are active, or sediment-retaining. These are bank-protecting spurs, groins, underwater breakwaters with traverses and some others.

Structures in the form protective coatings, the main function of which is the direct protection of the coast from the destructive action of waves and currents, are called passive or wave-protective.

Bank protection structures are of three types: heavy, light and in the form of a vertical wall. The heavy type includes structures made of concrete and reinforced concrete slabs, asphalt pavements, rock fill, etc. Bank protection structures light type they are built in the form of gravel, crushed stone or sand filling, fascin and brushwood coatings, plantings of various plants.

One of the most common ways of fastening coastal slopes is rockfill. Usually, a medium-sized ragged stone (from 15 to 70 cm) is used for these purposes, since the use of small stones does not ensure the stability of the slope, and large stones form large gaps that violate the integrity of the slope. The riprap anchor (fig. 4.1) consists of a return filter or drainage layer of sand, crushed stone and gravel, on which is placed a layer of stone. The riprap is usually supported by a thrust prism, the purpose of which is to prevent rocks from sliding and soil being washed out. Typically, riprap fastening is used under the following conditions: the height of the underwater slope is from 2 to 8 m; estimated ship wave height - up to 1 m, wind wave height from 0.7 to 2 m; soils that make up the slope, sandy and clayey; ice thickness - up to 1 m.

Sometimes boxes and cages made of various materials are used to protect slopes, as well as bags made of wire mesh, called gabions, which are filled with stone. Gabions have dimensions: length - 1.5-2 m, width - 1/3 of the length and height of 1/8-1/10 of the length. Gabions laid on a slope long side parallel to the edge. The advantage of gabion masonry is that, being flexible, this type of bank protection does not collapse with uneven soil precipitation, well keeps the soil from being washed out and freely passes water. On the seas and reservoirs, to protect the coast, a sketch of shaped blocks is used: dipods and tetrapods. Such blocks have good wave damping ability and stability, they are recommended to be used
at wave heights over 2 m.

Reinforced concrete and asphalt slabs are often used for fixing slopes.

Rice. 4.1 - Rockfill bank protection options:
a - in the form of a stone prism; b - in the form of a layer of stone:
1 - fixing the bottom with crushed stone or gravel; 2 - a sketch of a stone; 3 - emphasis;
4 - surface slope cover; 5 - backfilling the slope with sandy soil;
6 and 7 - bedding at the base of the outline; 8 - rockfill;
9 - border of the main fastening; 10 - lightweight mount

On fig. 4.2 shows the scheme for fastening slopes with precast concrete split slabs. For this type of fastening, plates of various sizes and shapes are used: rectangular, hexagonal, ribbed, solid and with holes. Slabs 1 are laid on a three-layer return filter, the lower layer of which is 10 cm thick consists of coarse sand 4, the middle (also 10 cm layer) is made of fine crushed stone or gravel 3, and the upper layer 15 cm thick is made of coarse crushed stone 2.

Between themselves, the plates are fastened with hinged clamps or welding of reinforcement outlets. A stone prism or reinforced concrete thrust slab serves as a support for slab bank protection. This type of fastening is used at wave heights up to 1.5 m and ice thickness up to 0.6 m.

A relatively simple type of shore fastening is asphalt concrete pavement, which is distinguished by the absence of a return filter, low cost and ease of repair. Such coatings are monolithic and prefabricated. Monolithic asphalt concrete pavements are applied to a pre-planned and compacted slope. Prefabricated asphalt pavements in the form reinforced slabs they are laid on the surface slope, after which the reinforcing bars are welded and the seams between the plates are filled with hot bitumen. Asphalt slabs are laid overlapping on underwater slopes.

Bank protection made of brushwood is flexible and due to this it is well preserved when the base is deformed. The simplest design is brushwood lining, consisting of several layers of brushwood (Fig. 4.3). On top of each layer, rod ropes are laid, fixed with willow stakes hammered into the ground. To prevent the brushwood lining from floating up, it is overloaded with stones.

Rice. 4.2 - Scheme of fastening slopes with precast concrete split slabs:
1 - national team reinforced concrete slab; 2 - large crushed stone; 3 - small crushed stone or gravel;
4 - coarse sand; 5 - stone prism; 6 - hinge clamp

Brushwood mattresses and reed carpets are often used to strengthen the banks. A brushwood mattress is an elastic structure consisting of scattered brushwood, laid in two intersecting layers and pulled together with two nets of brushwood ropes or wire.

The reed carpet consists of reed canvases, on which reed fascines are laid (fascines are called a bundle of reeds or brushwood, tied in two or three places with wire or wicks). Cloths together with fascines are placed on a frame made of welded reinforcing mesh.

In some cases, expensive types of bank protection can be replaced by planting vegetation on the slope. The germinating root system of shrubs, as well as their branches and leaves, protect the coastal slopes from the effects of waves and currents. Due to the vegetation on the coastal slope, the roughness of the channel increases, which leads to a decrease in the speed of the current in areas adjacent to the coast and softens the blows of ice floes.

Bank protection by sowing grasses and sodding is used on surface slopes that are flooded only in high water. This type of fortification protects coastal slopes from erosion by rainwater and wind erosion.

Rice. 4.3. Strengthening slopes with brushwood lining:
1 - mattress with stone loading in wattle cages; 2 - lining;

Below low water levels - 2.5-4.0;

From low water to maximum spring floods - 7-20;

From maximum floods to the level of wave run-up - 4-10;

Before pairing with the shore 1.5-2.5.

Bank protection structures in the form of a thin wall are piles or sheet piles driven in a row tightly to each other. To prevent the wall from tipping over, it is often reinforced with anchor ties installed 3-4 m apart.

Rice. 4.4. Bank protection design option in the form of a vertical wall:
1 - reinforced concrete sheet pile; 2 - cap beam; 3 - stone covering; 4 and 7 - bedding
from sand; 5 and 6 - surfaces of slopes from sand and clay soil; 8 - design bottom;
9 - medium building level; 10 - wall clogging level

To protect the banks, vertical walls of unanchored or anchored reinforced concrete sheet piles are currently used. The bank protection design in the form of a vertical wall made of unanchored tee sheet pile (Fig. 4.4), developed by the Giprorechtrans Institute, is recommended for soils that allow sheet pile driving at an underwater anchorage height of up to 3.5 m and a wave height of 0.7 to 2.0 m.

We bring to your attention the journals published by the publishing house "Academy of Natural History"