Technology of sheet piling fencing of pits. Sheet piling technologies Sheet piling fencing of excavation walls types and calculations

In conditions of weak soils prone to loss of stability when dynamic influences are applied during pile driving, movement construction equipment, unloading building materials etc., both deformations of pit fencing and spacer structures, subsidence and uplift of soil into the underground structure, accompanied by soil subsidence and deformation of the foundation structures of buildings adjacent to the excavation pit being developed, can occur.

In this regard, taking into account the schemes presented in Fig. 3.3-3.12, we will consider the most common technical solutions for ensuring the stability of sheet piling.

Rice. 3.3.

a- console; b - with horizontal fastenings with steel beams; c - with anchor walls made of sheet piles; G- with horizontal anchor plates; 1 - sheet piling; 2 3 4 - anchor wall made of sheet piles; 5 - steel anchor rods; 6 - anchor plates laid on the ground

A. Open pit

• 1. Cantilever fencing, including those with stiffening belts made of steel beams of various sections, is used for pits up to 4-5 m deep, limiting dynamic impacts when moving construction equipment and prohibiting the storage of materials near the fence (Fig. 3.3, A). At the same time, in soft soil conditions, it is necessary to ensure that the sheet pile is buried below the bottom of the pit to at least 2/3 of its depth. To provide collaboration When installing a sheet pile along the top of the fence, a strapping beam made of rolled steel, mainly I-beams, paired channels, or tongues, must be installed (Fig. 3.3, 2).
• 2. Temporary spacers horizontal fastenings from metal cans of various sections (mainly pipes with a diameter of 450-720 mm, I-beams or sheet piles connected by welding) with a pit width of up to 15-20 m (Fig. 3.3, b). For large pits, intermediate rack piles made of sheet piles or column I-beams are used, as well as structural elements walls of the building, carried out before the development of the soil during the stage-by-stage excavation of the pit along the grips (Fig. 3.4, 3). Spacers are arranged in one or several tiers with a step determined by calculation, which is usually 4-6 m.

Rice. 3.4.

I - sheet piling; 2 - distribution belt (banding beam); 3 - horizontal steel beams; 4 - intermediate supports (piles-racks) made of sheet piles

Rice. 3.5.

a, c- strapping beams made of I-beams; b- assembly for fastening the anchor rod to the strapping beam made of channels; V- strapping beams made of two I-beams; d,f- strapping beams made of two and one sheet piling, respectively; / - tongue and groove; 2 - I-beam; 3 - steel pin; 4 - steel pipe or wooden beam; 5 - channel; b - steel supporting gusset; 7 - anchor rod; 8 - thrust steel plate; 9 - steel washer; 10 - screw; 11 - fixing steel wedge

Design solutions for fastening sheet piling fences for pits up to 10-15 m wide are presented in Fig. 3.5, A, for pits up to 20-30 m wide in Fig. 3.6.

3. To reduce metal consumption, inventory steel frame elements with replaceable end parts can be used as spacer systems for fastening sheet piles

Rice. 3.6.

(Fig. 3.7, A). Jacks are included in the outer rods adjacent to the sheet pile, allowing you to monitor the movements of the pit fencing and control the forces in the spacers.

Rice. 3.7.

A- steel inventory frames with jacks; b- reinforced concrete trusses; I- tongue and groove; 2 - strapping beams; 3 - steel inventory frame elements;

4 - jacks; 5 - reinforced concrete trusses (intermediate supports are not shown)

Frame structures in some cases are made of horizontal reinforced concrete trusses with intermediate posts

• (see Fig. 3.7). After developing the pit, such structures can be included in the ribbed floors of the underground floors of the structure. On trusses that cover pits of large spans, it is possible to place construction and technological equipment, as well as storing materials during the construction of the underground part of the building.
• 4. Fastening the fence to vertical anchor walls or horizontal slabs with steel rods at a distance of at least S = N k tg(45° - Нк - pit depth, c, d). Such a constructive solution for fencing requires additional areas beyond the boundaries of the pit. It does not provide horizontal stability below the bottom of the pit. The attachment point for the anchor rod to the fence is shown in Fig. 3.5, b. Anchor walls can also be constructed from groups of sheet piles (2-3 gypsum), immersed every 2-5 m along the contour of the fence. Anchor rods are made from reinforcing bars, which allows you to adjust their tension depending on the horizontal movements of the sheet piling. When the pit depth is over 6 m, anchor rods are installed in trenches laid 2-3 m below the ground level.
• 5. “Island” method with ground berms and braced fastenings made of steel beams or trusses resting on sections of the foundation slab or on temporary pile-columns made of sheet piles or I-beams, immersed in the bottom of the pit (Fig. 3.8, a-e). The pit is developed in stages: first, the soil is dug out to its full depth, with the exception of zones (soil prisms or berms) adjacent to the sheet piling, then corner horizontal struts from pipes are installed, sections of foundation slabs are made in the pit, into which the braced fasteners rest, on the second stage, the final completion of the pit is carried out and the underground structures of the building are erected. With the necessary design justification, the fastening of sheet piling can be done by supporting horizontal struts in the structure of the building under construction (floors or walls) (Fig. 3.8, V). Spacer structures are sequentially dismantled as the building structures are erected and the pit is backfilled.
• 6. Fastening sheet piling fences with soil injection anchors, buried in dense soils beyond the zones of active soil pressure on the fences and taking up pulling forces (Fig. 3.8, G). The amount of effort perceived individually

anchor for clay soils is in the range from 0.1 to 0.5 mN. Anchors are placed along the perimeter of the pit in increments of 0.8-3.0 m with a horizontal inclination angle of up to 30-60°. Anchor rods are made from drill pipes, reinforcing bars, ropes or pipes, which are used when drilling and flushing a well with cement, clay or polymer solution. For fastening with sheet pile wall holes are made in it, and the anchor rods are attached to a steel strapping beam made of a channel or I-beam. In conditions of weak soils, this solution has limited use, since it requires deepening to significant depths (over 25-30 m), and when installing anchors under existing utilities, roads or buildings, additional deformations may occur in the structures of the latter due to changes stress-strain state of the soil due to its interaction with the embedding of the anchor. This design solution, despite the increased requirements for the quality of work and qualifications of the contractor, high cost and labor costs, is effective for large-volume pits when it is not possible to use spacer structures installed inside the pit.

7. Strengthening the soil along the entire depth of the sheet pile, as well as creating soil-cement diaphragms over the entire area below the foundation pit using jet cementation technology (Fig. 3.8, d). To create continuous diaphragms up to 1500 mm thick, soil-cement piles are arranged on a grid of 600x520 mm, the design strength of the soil-cement material is assumed to be about 1.0 MPa, and the deformation modulus is 400 MPa. The consumption of materials per 1 m of drilling is: water 200-350 l, cement 300-650 kg; complex additives 7-12 kg.

Rice. 3.8.

a B C- with ground berms and struts into the foundation slab; G- with ground anchors; d- with soil-cement diaphragms made using jet technology; 1 - sheet pile fencing; 2 - distribution belt (banding beam); 3 - temporary, soil berm; 4 - steel strut or truss; 5 - foundation slab or piles; 6 - temporary anchor wall (solid or intermittent); 7 - load-bearing structures of the underground floor; 8 - horizontal steel beams; 9 - ground anchor;

10,11 -vertical and horizontal soil-cement massif

B. A closed pit in which sheet piling is a permanent structure that takes the loads fromdesigns building

I. Fastening the fence using horizontal floor discs, concreted using the “top-down” technology (top-down). With this technology, sheet piling can be combined with trench fencing concrete walls in the ground. The development of the soil is carried out through technological openings in stage-by-stage floors, concreted directly onto the formwork laid on the ground. For floor supports, permanent piles are used - columns, installed before the main contour of the pit fencing is completed.

To increase productivity when extracting soil and concreting floors, the so-called “semi-closed” method is used (semi top-down), when, along the contour of the sheet piling, cantilever sections of floors 3-6 m wide and large openings in the center are arranged, which are concreted after complete removal of the soil and installation of waterproofing of the lower level (Fig. 3.9, A). Overlappings along the perimeter of the pit are carried out using the “top to bottom” method, and in the central part, after removing the soil, classic scheme- "down up". The pit fencing is secured due to the spatial work of the perimeter sections of floors.

With this scheme, two options for performing work are possible.

Option 1. The installation of sections of floor discs along the perimeter is carried out in the process of stage-by-stage excavation of soil from the pit in the following sequence (Fig. 3.10):

• immersion of the sheet pile along the perimeter of the structure (Fig. 3.10, A);
• immersion of column piles (Fig. 3.10, b);
• concreting the floor slab of the first underground floor on the ground;
• within the contour of the slab, technological openings are arranged through which the soil will be extracted and descended necessary equipment and workers (Fig. 3.10, V);
• extraction of soil within the first underground floor to the surface and installation of an underlying monolithic floor with technological holes (Fig. 3.10, G);
• the specified operations of sequential soil extraction and installation monolithic floors repeat until the level is reached

Rice. 3.9. Methods for constructing underground structures using top-down technology: a- semi-closed method; b- with inventory steel trusses; 1 - tongue and groove; 2 - monolithic ceiling; 3 - intermediate piles-columns; 4 - technological hole for soil extraction; 5 - inventory farms

construction of the last underground floor by installing a monolithic slab on the ground with horizontal waterproofing (Fig. 3.10, d). On last stage excavation equipment and formwork are removed from the last underground level through technological holes, which are then concreted.

Option 2. Preservation of soil berms that prevent the movement of sheet piling until the installation of floors. The work is carried out in the following sequence (Fig. 3.11):

• the sheet pile is immersed around the perimeter of the structure (Fig. 3.11, o);
• from the level of the ground surface, outermost piles-columns are made (Fig. 3.11,5) to further support the floors along the perimeter of the sheet piling fence (Fig. 3.11, b);
• develop a pit to the design level while maintaining soil berms along the perimeter of the fence (Fig. 3.11, 7). From the level of the bottom of the pit, piles are made (Fig. 3.11,9), on which waterproofing and the foundation slab of the central part of the building are installed (Fig. 3.10, V);
• erect the frame structures of the central part of the building. In parallel, at the level of the ground surface, sections of floors along the perimeter of the sheet piling are concreted. To extract the soil, technological holes are left (Fig. 3.11, 7);
• in areas adjacent to the sheet pile, soil is removed through technological holes within the first underground floor. They arrange a monolithic ceiling, which I also connect! with the frame structure of the central part of the building (Fig. 3.11.6);

The specified operations of sequential soil extraction and installation of sections of monolithic floors are repeated until the level of the last underground floor is reached, with the installation of a monolithic slab. At the last stage, excavation equipment and formwork are removed from the last underground level through technological holes, which are then concreted (Fig. 3.11, e).

Rice. 3.10. Stages of technology for constructing underground structures using the “top-down” technology with load-bearing enclosing structures made of sheet piles: a d- stages of installation of underground structures; 1 tongue; 2 - jib crane; 3 - vibrating loader; 4 - intermediate piles-columns; 3 - drilling rig; b- grab; 7-technological hole for soil extraction; 8 - monolithic ceiling; 9 - excavator; 10 - support tables; 11 -concrete mixer truck; 12 - concrete pump; 13 - above-ground load-bearing structures; 14 - monolithic slab with horizontal waterproofing, foundations laid on the ground 69

Rice. 3.11.

/ - tongue and groove; 2 - jib crane; 3 - vibrator; 4 - drilling rig; 5 - column piles along the perimeter of the fence; 6 - grab; 7 - soil berms; 8 - foundation slab of the central part of the building; 9 - bored piles installed from the bottom of the pit; 10 - monolithic floors along the perimeter of the sheet piling; // - technological hole for soil extraction; 12 - monolithic ceilings of the central part of the building;

13,14 - concrete pump and fuel mixer truck, respectively; 15 - excavator

There are solutions developed by MIIOSP named after. Gersevanov, in which inventory equipment is installed in the upper tier of the pit metal constructions farms (see Fig. 3.9, 5). The trusses are supported by sheet piling, and the underground floors, concreted in stages as the soil is excavated, are suspended from the truss structures. After concreting the building frame elements, temporary suspension structures and trusses are dismantled.

The method makes it possible to minimize the influence of construction processes and underground soil development on the stress-strain state of the pound massif and structures located nearby buildings and structures. At the same time, this technology is the most expensive and requires high qualifications from a specialized construction organization.

The composition of machines that makes it possible to implement these technologies in a complex mechanized way is presented in Table. 3.4.

Table 3.4

List of machines and equipment used in the technology of constructing underground structures using the “top-down” technology with load-bearing enclosing structures made of sheet piles

Technological stage	Equipment used
Sheet piling	Vibrating loader on a crane, drilling rig or excavator
Device intermediate pile-columns	Drilling rig, pneumatic wheel crane, concrete pump, fuel truck
Device monolithic floors	Pneumatic wheel crane, welding unit, concrete pump, concrete truck
Removing soil from under floors	Mini-excavator on pneumatic wheels, grab on a crane. It is possible to extract soil to the surface through technological holes along belt conveyors installed on the floors of underground floors

Possible Constructive decisions The fastenings of monolithic floors to sheet piling fencing are shown in Fig. 3.12.

Based on the presented technological schemes Taking into account the analysis of the experience of working in difficult soil conditions on the installation of sheet piling fencing and their fastenings, the authors calculated technologically several options for fastening the fencing of a conditional PIT with a depth of 6 m with plan dimensions of 40x30 m. The length of the sheet pile is 18 m. The following technological options were considered:

• option 1 - installation of temporary horizontal spacer beams made of steel pipes with a diameter of 630 mm, mounted in increments of 6 m, with intermediate support on sheet piles; For all options, a strapping belt made of a steel I-beam with a height of 400 mm is installed around the perimeter of the fence;
• option II - “island” method with soil berms and braced fastenings made of steel pipes 12 m long with a diameter of 426 mm, installed in increments of 6 m and secured to sections of the foundation slab in the pit;
• option III - fastening sheet piling fences with ground injection anchors from rods with a diameter of 73 mm and a length of 30 m, performed in one row with a step of 2 m; anchors are provided using Titan technology (Ishebeck GMBH) ;
• option IV - fastening the fence with steel rods to a discontinuous anchor wall made of sheet piles (three sheet piles of the 4Z-36-700 Arcelor brand per pile) 9.5 m long. Rods with a diameter of 75 mm, a length of 15 m are laid in increments of 5 m in trenches with a depth of 2 .0 m;

Rice. 3.12.

a- on steel support tables; b, V- on monolithic reinforced concrete belts; 1 - tongue and groove; 2 - beam or floor slab, 3 - horizontal steel beam, 4 - support table welded to the tongue, 5-monolithic

reinforced concrete belt

option V - cementation of the soil along the entire depth of the sheet piling, as well as the creation of soil-cement diaphragms 2 m thick under the bottom of the pit with a pitch of 600x520 mm (close to the sheet piling with a pitch of 500x440 mm).

Cost indicators were adopted based on territorial current unit prices and data from suppliers of building materials. The timing of the work was calculated according to ENiR standards, taking into account the productivity of modern equipment. Manufacturability criteria were calculated using formulas (2.1)-(2.3).

Differential (simple) criteria for the manufacturability of the device for fastening sheet piles are presented in Table. 3.5.

Table 3.5

Simple criteria for the manufacturability of the installation of sheet piling reinforcements

Options		Simple criteria for manufacturability X.
		Cost, thousand rubles	Metal consumption, t	Cost of materials, thousand rubles	Labor costs	Area increase factor	Duration, days
	With horizontal struts
	With soil berms
	Unpaved anchors
	With anchor wall
	Jet cementation

Note: highlighted in the table best values according to the considered indicator of manufacturability; the area increase coefficient was calculated as the ratio of the area occupied by the fencing structures to the area of ​​the pit; When calculating the productivity for option 3, the work on developing the pit and installing sections of the foundation slab was taken into account.

Results of bringing simple criteria X in dimensionless quantities are given in table. 3.6

Table 3.6

Simple criteria in dimensionless form

Options		Simple criteria in dimensionless form: T" = x„ /xG % , T" = xG/x «
		Price	Metal intensity	Cost of materials	Labor costs	Increase	Duration
	With horizontal struts
	With soil berms
	Ground anchors
	With anchor wall
	Jet cementation

To calculate the generalized and integral criteria for manufacturability, the weight coefficients /-x, /^ were determined depending on the significance of each criterion according to the method of V. G. Gmoshinsky, adopted in engineering forecasting.

For example, for a test pit during the construction of the second stage of the Mariinsky Theater with the loosening of sheet piling steel pipe the value/^ was 1.3%, which required additional reinforcement of the sheet piling in the form of soil consolidation using jet grouting methods.

It should be noted that when installing sheet piling fencing for pits located near historical buildings in soft soils, values ​​of equivalent rigidity should be taken^

Taking into account the above in table. 3.10 presents modern experience in constructing sheet piling fencing for pits over 6 m deep in St. Petersburg, showing that the use of special, mainly vibration, technologies for driving sheet piles in combination with additional measures for the installation of various retaining systems ensures proper quality and stability of pit fencing.

The choice of technological parameters for the installation of sheet piling fencing and systems for ensuring their stability in conditions of weak dynamically unstable soils is an important technical task that requires, first of all, competent calculation justification based on modern techniques and software systems. The basic principles and methods for calculating sheet piling are discussed in the next section.

Examples of installation of sheet piling fencing for pits in St. Petersburg

Table 3.10

		Technology dives
TRC Gallery, Litovsky Ave.		Vibrating		Ground anchors and ground berms and struts supported on a foundation slab
Shopping center Stockman, Nevsky pr.				Ground-cement diaphragm at a depth of 17-20 m. Wall in the ground, floors arranged using top-down technology
Administrative building of the bank, Malookhtinsky Ave.
Second stage of the Mariinsky Theatre, Kryukov Canal				Overlapping using top-down technology, jet technology
Hotel complex Park Inn, Goncharnaya st.				Wall in the ground. Horizontal spacer beams
Office center, Pochtamtskaya st.				Soil-cement i diaphragm at a depth of 7-10 m. Horizontal spacer beams
Reconstruction of the building into a hotel complex, emb. R. Moiki, 73, 75, 77, 79		Indentation		Overlapping using top-down technology
Residential building, Deputatskaya st., 34A		Vibrating		Ground berms and horizontal bracing beams

End of table. 3.10

		Technology dives		Sheet piling fastening technology
Office center, Nevskaya Town Hall, Degtyarny ner.		Vibrating		Ground anchors 30 m long
Residential complex, Medikov Ave., 10				Horizontal spacer beams
Residential building, Rybatsky Ave.,			12-20	Ground berms and struts supported on a foundation slab
Residential building, st. Pobeda near the house 18 GG on Moskovsky Ave.		Indentation Vibrating		Horizontal spacer beams in two tiers on intermediate columns
Residential building, st. Smolny, 4, bldg. B-2, B-5, B-6		Vibrating		Horizontal spacer beams on intermediate columns
Automobile plant "Magna" in the village. Shushary, Moskovskoe highway.				Horizontal spacer beams

Note: //.. L- pit depth and sheet pile length, respectively.

Sheet piling fences are piles driven into the ground along the entire perimeter of the pit, made of wood or metal.

The installation of such structures is carried out in places where it is impossible to carry out work on slopes.

Purpose of structures– this is the protection of the pit and the lives of workers from soil collapse. The soil is reliably held and does not collapse during the construction of even the most complex objects.

Larsen tongue and groove

Protection from storm and groundwater, as well as from soil collapse, is carried out by special piles - Larsen tongue and groove. They bear the name of their founder and developer of this technology.

Larsen tongue and groove is a particularly spatial element with a box-shaped section and locking elements along the edges of the product.

When immersed in the ground, the clamp standing on one element is installed in a special groove of the other. This design implementation guarantees reliable docking.

Construction tongues are made from durable metal with carbon impurities. To protect against corrosion, manufacturers add copper particles to the metal product.

Save if necessary You can use sheet piles made of polyvinyl chloride, which are not inferior in strength and reliability to metal and reinforced concrete structures.

Among main advantages Larsen tongue and groove can be distinguished by its convenience when installing the material on site.

Possessing high strength and resistance to external factors, Larsen sheet piles, unlike conventional sheet piles, are used in the construction of complex objects. Among application examples The following can be noted:

• treatment facilities;
• protection of construction sites from water;
• strengthening the coastline of rivers and reservoirs;
• fencing areas with walls containing industrial waste;
• construction of dams, bridges and piers;
• soil strengthening with the threat of landslides.

Reliability is achieved through the manufacture of sheet piles from alloy steel, which has increased strength. Manufacturers set the thickness of the tongue in different ways during manufacture. U famous brands it varies from 15 to 23 mm.

Sometimes during operation Unforeseen situations happen, and the product, immersed in heavy soil, begins to malfunction: the connections in the locking elements are deformed, and the structure itself is bent.

The masters have only one way out - cut off part of the structure autogenous installation and leave it at the work site.

Larsen sheet piling is carried out using special equipment by shock and vibration influences. Installation is in many ways similar to installing fence piles.

Immersion using a vibrating element is carried out using a hinged module, through which the load is transmitted to the place of the head of the hinged element.

Additional equipment for installation is axial technology, which allows you to insert a pile into soil liquefied under the influence of a vibrating machine.

Reinforced concrete piles

Piles made of reinforced concrete structure, installed using locks, sealing the entire structure. Trapezoidal tongues and grooves are components of the lock elements. During installation work, piles are installed one into the other.

Installation of piles is carried out using driving technology with increased technical capacity. Piles made of reinforced concrete material are not removed for re-work, since they serve as outer shell foundation.

Such piles are often used in the construction of bridges and dams. Transportation aggravated by the appearance of cracks on the surface of the product. such products do not exceed sixteen meters.

Steel sheet pile supports

Metal material used repeatedly, and, moreover, it is easy to transport and install at a new facility. Steel sheet pile supports are used in modern construction, based on a number of reasons:

1. High strength to mechanical damage.
2. Convenient transportation and installation, compared to reinforced concrete structures.
3. Reusable and easy to remove from soil.
4. Wide range of materials from a profile, price-oriented different kinds object according to complexity.
5. Installation of profiles is carried out using equipment using vibration and impact technologies.

Installation of sheet piling for a pipe pit

Sheet piling fencing of a pit made of pipes is carried out at the initial stage of construction work in a transport, housing or hydraulic structure.

At the initial stage of work the pit may crumble and damage builders and equipment.

Prevention of such situations is successfully achieved pipe pile technique, consisting of dense wall, where the fastening elements are connected to each other by locks in the grooves.

Carrying out excavation work involves installing a structure for support; this can be a Larsen trough-shaped sheet pile or a tubular sheet pile.

Pipe sheet pile has the only drawback in which it is inferior to Larsen sheet pile - high cost for hardware with increased weight, and in other indicators better protection the pit cannot be found.

Main advantages installation of sheet piles from pipes in the pit:

• high stability The product allows the use of tubular sheet piles as permanent formwork;
• installation becomes more convenient due to the ability to crush boulders and other foreign bodies inside the pipe;
• stability is much higher than that of Larsen tongue and groove;
• the ability to install additional beams and channels inside the pipe;
• Used pipes can be dismantled and used in other construction work or sold on the secondary market.

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Standards in the technological map and SNIP

The standards for fencing using the sheet piling method are prescribed in technological map .

The map was developed based on experience in construction at similar sites with a repeating structure of buildings, structures with parts, as well as for buildings with unified dimensional schemes and standard designs.

In it the basics are covered high-quality execution work, fire and environmental safety and other important points and questions that arise during construction work of increased complexity.

The map is designed for foremen, construction workers and engineers involved in technical aspect in the construction of sheet pile structures.

Quality of work performed assessed according to SNIP – « building regulations and rules”, by which you can navigate and talk about the competence of the work and the construction of the fence in the pit.

It reflects the requirements for fire and environmental safety of work and the material and technical component, which must be aimed specifically at the norm, and not at deviation from it.

Formula for calculation

When digging up the soil, the balance of forces in the interaction is significantly disrupted. The pressure when removing soil increases on the cooling side of the walls.

Preventing wall destruction by fencing must be calculated using specific design characteristics: fencing, depth to which the material is immersed, sheet pile dimensions and interaction forces.

The calculation is made graphically (example in the photo below) or according to a certain formula. A special program is used for calculation. Technical information required for correct device and immersion of the tool, is given in paragraph 3.02.01-87 SNIP.

Characteristics, taken into account in the formula:

1. Ground pressure under overturning.
2. Vertical soil pressure force.
3. Resistance to rotating element.
4. Selected pit depth.

Calculation formula strength looks like this: M1 ≤ m/γ * M2, Where

• M1— the main moment of the overturning force.
• M2— counteraction to the force of overturning (holding moment).
• m— coefficient of working conditions (in general procedure it is equal to 0.95, for soft soils 0.7)
• γ — reliability coefficient (1.1 for an area covered with water).

The main points of strength can be calculated based on the formula:

• M1 (overturning moment) = Ea*Ca.
• M2 (holding moment) = En*Cn.
• Ea and En – graph resultant pressures active and passive types; Ca and Cn are the resultant arms with respect to point 0.

The calculation is carried out based on the lowest point of the sheet pile, since at a height it can be rotated or tipped over.

Calculation example

According to the calculated data for sheet pile fencing with the number of tiers equal to two or more “VSN 136-78”, for sandy soil the coefficient of active lateral soil pressure is 0.7, passive 1.42, the distance from the top of the sheet pile to the bottom of the layer will be 9 m.

For minimum depth sheet pile 28.9 m, the lateral pressure diagrams are: active 16.6 tf/m2, active 23.8 tf/m2.

Installation and strengthening of Larsen tongue and groove

Larsen dowels are easy to install and fasten, but Installation requires the help of special equipment. Before starting the installation, you need to invite a team of workers of three, or preferably four people, trained in the skills of carrying out such work.

During installation it is impossible to do without a vibrating hammer. If the vibrator is not available, the use of a vibrating hammer is allowed. This is a device without which not a single job of driving piles or strengthening a fence can be done.

If your financial capabilities do not allow you to purchase such useful equipment, you can rent it.

With the help of such a hammer, the tongue and groove are driven into the ground. Thanks to the sharp impact and technical force, the need to use heavy equipment disappears.

Tongues installed sequentially, so that the second fits neatly into the groove of the first. In this case, a turn is needed within a radius of 180 degrees in relation to the first one to form a continuous structure.

The technology of high-quality tongue-and-groove pressing is the most acceptable installation technique. It does not cause significant damage to the soil and nearby buildings, which cannot be avoided when using a hammer.

The process of immersion and removal of pipe piles is shown in the video below:

Unfortunately, quite often we are faced with ineffective design solutions regarding the installation of sheet piling. This article is intended to make it easier to understand various technologies and their price characteristics.

So, you finally have in your hands a long-awaited project with a positive expert opinion and a great desire to quickly get to the construction site and start work. But a positive conclusion does not mean at all that the design documentation was developed on the principles economic efficiency and reasonable sufficiency. In this article we will try to answer the most popular questions.

In 95% of cases, the main material for the construction of the load-bearing structure of sheet piling is Larsen sheet pile and used pipes. We often see in project documentation that the author of the project played it safe. And he did it at the expense of the customer. An incorrect choice of design and immersion method can increase the customer’s costs by 10 or 20 million rubles or even more, depending on the scope of work. To start short description technologies for driving sheet piles into the ground.

Vibration loading of sheet piles(pipes, Larsen sheet piling)

Vibration immersion is a modern, quite expensive technology that requires complex equipment and qualified specialists. The vibratory loader copes equally well with pipes of all diameters, Larsen sheet piles and its analogues, I-beams, etc. Equipment based on cranes (as in the photo) or based on excavators. Vibration immersion is a non-alternative method when working in sandy, water-saturated soils. The cost of vibro-immersion (work) for our conditional 500 sheet piles is around 700 rubles per linear meter. But when working in open field, far from existing buildings and structures, in the presence of clay soils, there are cheaper and faster ways to immerse sheet pile elements.

Driving the sheet pile (driving the sheet pile by driving it)

This is perhaps the simplest, fastest and cheap way sheet piling, which is used quite often, but has a number of limitations. Let's start with the pipe. Driving is carried out with a diesel hammer, similar to driving piles. A small hole is made in the pipe with a gas cutter so that it can be picked up with a hook and inserted into the head of the hammer. Next, the pipe is driven to the desired design level. It is possible to pre-drill a leader well if geological conditions require it. Wells, as a rule, do not collapse. IN in this case The problem is the water-logged sand, which quickly draws in the drilled well, but the pipe will overcome it under strong and forceful blows of the hammer.

The price of the issue, of course, depends on the diameter of the pipes and the volume of work, but let’s take a conditional 350 rubles per linear meter for a volume of work of about 500 pipes.

As for the Larsen tongue, it can also be driven in with a hammer. A special cap with a petal grip is put on the hammer and then the technology is no different, except that the Larsen must be immersed “in the lock.” The slightest error in the driving process and a powerful hammer blow pulls the tongue out of the lock. In this case, practically nothing can be corrected. Therefore, for Larsen sheet piles, vibration immersion is, of course, much preferable. The cost of driving Larsen sheet piling is about 500 rubles per linear meter due to the increased requirements for the quality and accuracy of the work.

Limitations of using the driving method: noise, dynamic loads from the hammer impact, it is more difficult to remove pipes due to high level pinching and increased soil compaction during driving. That is, the technology is not suitable for dense buildings (city center). But if the distances allow, and there are no plans to remove the pipes, plugging is the best option.

The essence of the technology comes down to drilling wells with a diameter slightly larger than the diameter of the pipe and lowering the pipe into the wells. For 219 pipes the auger is 250, for 325 - 350, for 426 - 450, etc. The technology is silent, fast, convenient and, in our opinion, optimal if the soil is not saturated with water. In water-saturated soils, the well will quickly silt up and the pipe will not be immersed without additional methods of influence. Drilling for pipes can be done with anything: a pile driver (in our case), a hole drill, small-sized self-propelled drilling rigs such as Berkut, a hydraulic drill based on an excavator, or a manipulator. The simplicity of the technology makes it the most widespread and frequently used. The absence of pinching of the pipe in the ground, contrary to the opinion of many “experts,” is not a disadvantage. Just look at the diagram below to understand that underground part will not allow the pipe to tilt, much less fall. The slope of the pipe is shown schematically here. In practice, it is not visible, the slope is within the immersion error and in accordance with SNiP tolerances. But a pipe immersed in this way is much easier to remove. True, if more than a year has passed since the immersion, the soil will compress the pipe as tightly as if it had not been drilled under.

Tongue Larsen is not immersed in this way, although leader drilling with a small diameter is sometimes also used under Larsen in order to disrupt the soil structure and facilitate the process of vibration immersion.

The cost of pipe immersion and drilling depends on the diameter and scope of work. With a nominal volume of 500 pipes, the cost of drilling for a pipe will range from 370 rubles for 219 pipes to 500 rubles for 426 pipes. Let us repeat, the technology has practically no disadvantages. But pipes, of course, will not replace Larsen sheet pile where it is needed. And it is correct to immerse Larsen using vibration immersion, and only with it.

There is perhaps only one limitation to this technology - heavily watered soils. Under such geological conditions, the newly drilled well is drawn in by silty and sandy soil and it is no longer possible to immerse the pipe there without additional manipulations.

Pressing in the tongue(Crushing)

Indentation is the quietest and most silent technology available. But you can’t do without shortcomings. Pressing installations are very cumbersome, require good preparation of the construction site, electricity 380V 50 kW, and are also quite slow. Hence the high cost of work, and most importantly, the cost of relocation, which constantly scares off customers with small volumes of work. The fact is that due to its enormous weight, the installation in the dismantled state is transported by 5-6 vehicles, and the main platform, even in the dismantled state, weighs 60-80 tons and is an oversized cargo in width. Installation of Larsen tongue and groove by pressing is possible only with certain restrictions, so before ordering installation it is necessary to consult with specialists. The cost of pressing sheet piles and pipes is from 700 rubles per linear meter.

The production enterprise "Arctic Hydro Stroy", specializing in piling work, will perform sheet piling fencing of the foundation pit in Moscow and the central regions of the Russian Federation.

During the construction process on “virgin land” it increases. It becomes deformed and can “float”. This leads to damage and even sometimes to the complete destruction of nearby buildings.

Therefore, within the city limits or in a built-up area, when constructing new objects, foundation pits are fenced with sheet piles.

In accordance with 3.02.01 SNiP (“Earth structures”), sheet piling fences must be installed in all pits from two meters deep.

The fencing also simplifies work at the site itself: it prevents soil from shedding and the collapse of the walls of the pit.

Why do they trust us?

• We strictly guarantee individual approach. We have been working for more than 10 years.
• We will offer the most suitable solution for you. More than 200 completed projects
• We have reasonable prices for all types of work. You will know what you are spending your money on.
• Free cost calculation and design of sheet piling fencing.
• All work is carried out by our employees. We have SRO approval.
• We have all the necessary equipment to carry out the work. Your own fleet of necessary equipment.
• We guarantee high quality materials used.

Experienced specialists of the ArktikGidroStroy company will construct high-quality sheet piling fencing of any level of complexity! In a short time and at an affordable cost.

What is fencing a pit with sheet piling?

The sheet pile fencing of a pit (or “”) is a wall, the load-bearing part of which is sheet piles immersed in the ground. It compacts the soil, localizes the area of ​​expected deformations, and limits their impact on neighboring buildings.

Sheet piling fencing for pits can be temporary or permanent - in the second case, they serve as permanent formwork for basement walls, foundations, and plinths. Used as for groundwater.

Possible uses:

• strengthening the sides of foundation pits, preventing walls from collapsing;
• restriction of the construction site;
• installation of hydraulic structures - dams, embankments, dams, bridges, etc.;
• strengthening foundations;
• creation of sealed tanks for industrial waste;
• fencing of landfills;
• strengthening railway tracks;
• protection of underground communications from groundwater, etc.

For your information

The depth of the pit at which tongue-and-groove fencing is necessary depends on the composition of the soil:

• sand – from 1 m;
• sandy loam – from 1.25;
• clay, loam – from 1.5;
• dense soil - from 2 m.

Types of piles for sheet piling fencing of pits

In the process of installing sheet piling for a pit, the following piles are used:

• wooden;
• reinforced concrete;

Wooden ones are knocked together from boards with a thickness of 4 centimeters or joined from bars using a tongue-and-groove method. Used at immersion depths within three meters. This is a one-time option, since wooden piles cannot be dismantled without damage.

The most difficult thing to drive is reinforced concrete piles. Due to the energy intensity of the process, this type is used only as a permanent fence; subsequently, reinforced concrete piles are part of the foundation. Manufactured with square section.

Metal ones can be used repeatedly (up to 20 cycles). They are made from profiled metal, pipes, and I-beams.

The Larsen tongue and groove looks in profile like a Russian L with rounded lower edges (tongue-and-groove locks).

The use of tubular sheet piles is preferable on unstable soils, which are characterized by horizontal movements. In such situations, the stability of the Larsen sheet pile may not be sufficient.

The strength and stability of the pipes is higher due to the large cross-section and wall thickness. Like Larsen tongues, tubular ones are equipped with tongue-and-groove locks on the side walls and can be connected into a single structure.

Installation is carried out using steel rotating elements (they allow you to create a wall with the desired spatial configuration).

Sheet piling technology for excavations

Sheet piling techniques:

• impact method;
• combinations of the first three.

Indentation

Indentation is the safest method for nearby buildings: constant monitoring of their condition during the work process is not required. Used in densely built-up areas, incl. on loose and marshy soils.

The disadvantage of this method is the bulky equipment, which is transported dismantled and assembled on site.

Vibration immersion

Vibration immersion is a fairly universal method.

Our vibratory submersible equipment copes with almost all types of sheet piles: pipes of any diameter, I-beams, Larsen sheet piles.

On sandy, water-saturated soil, the vibration method is often the only possible one.

But this technology is not among the cheapest due to the use of expensive equipment.

Hammering

Carried out with a hammer ( attachments for a pile driver), on dense soils - in pre-made leader wells. Restrictions for using the impact method are work in densely built areas.

When using sheet piling fencing for a pit, the price is the most affordable.

For your information

On so-called light soils, combinations of the above methods can be used. For example, a pile is initially driven using a vibration method, and is driven to the required depth level with a hammer.

Calculation of sheet pile fencing of a pit

During the process of digging a pit, the balance of interaction forces in the soil is disrupted: when excavating soil, the pressure on the fence from the walls increases. To prevent the walls from collapsing, the fence must have certain design characteristics. Stability depends on the magnitude of the impact forces, the size of the sheet pile, the depth of immersion, and the method of fencing.

The calculation can be performed using a graphical-analytical method or a numerical method (using a formula). There are special programs for this. Necessary Technical information(immersion standards, correction factors, etc.) are given in 3.02.01-87 SNIP.

The formula takes into account the features of the work:

• pit depth;
• overturning soil pressure;
• anti-torque;
• vertical soil pressure.

Formula for calculating strength in general view– M1< m/γ * M2, где

M1 – moment of rollover force;

M2 – anti-rollover;

m – operating conditions coefficient (from SNiP tables, for soft soils – 0.7);

γ – reliability coefficient (SNiP: 1.1 for dry soil, 1.2 – for high groundwater).

The calculation is performed at the lowest point of the sheet pile, since under pressure it will rotate (tip over) relative to this point.

Features of the fencing device

During the construction of the pit, its walls are strengthened. The latter consists of metal sheets either from edged boards. Subsequently, the backfill materials can be used as formwork when pouring underground structures. The intake is permeable, so when groundwater levels are high, dewatering is used. To create a waterproof fence, Larsen tongues are used. Connected together by tongue-and-groove locks, they form a solid, hermetic wall.

Often used before starting wall construction. It reduces the shock load required to deepen the sheet pile to the calculated depth, thereby reducing soil deformation and the risk of destruction of other structures due to shock vibration.

Used in the following cases:

• on soils with high density, if there is a risk of destruction of piles due to increased shock/vibration loads during immersion;
• if there are sandy layers in the soil section large thickness(from 2.5 meters), which can provoke soil displacement;
• to reduce vibration and shock loads to minimize the risk to nearby buildings;
• if without preliminary drilling it is impossible to load the piles to the design level.

Distribution belt technology for pit fencing

(otherwise known as strapping) is used to strengthen the installed wall. The function of the strapping is to distribute loads evenly between adjacent piles. It is made from channels or metal beams. Installed horizontally at a depth of no more than two meters from the surface.

System with anchorage can be lowered to the middle of the pit depth. When great depth There can be several belts at different levels.

In addition to spreader belts, struts and struts are used to enclose the structure.

The spacers are located horizontally in increments of about 5 meters, pushing apart the opposite walls of the fence. There must be at least four of them (in the corners of the pit). The struts are installed obliquely, supported on the foundation slab. In the absence of a foundation slab, installation of stops can be carried out on piles.

In the process of strengthening the wall, the strapping is installed first, the rest comes later.

Cost of sheet piling fencing for pits

Order tongue and groove fencing for the pit according to low prices it is possible in our company “Arctic Hydro Stroy”.

The final order amount depends on::

• on the number of piles, volume of work;
• remoteness of the object;
• complexity of terrain and working conditions.

Depending on your production needs and the characteristics of the facility, we will select a pile driver required power, on a wheeled or tracked chassis. We provide services construction companies and private developers, we load piles in any quantity in record time.

Sheet piling fencing for a pit in Sheremetevo, made by specialists from ArktikGidroStroy

Sheet piling in Moscow, made by specialists from ArktikGidroStroy

Sheet piling fencing of a pit made from Larsen sheet piles with spacers, made by specialists from ArktikGidroStroy

Indentation of the sheet pile performed by specialists from ArktikGidroStroy

Vibration driving of pipes and sheet piles during the construction of a temporary bridge, performed by specialists from ArktikGidroStroy

At the very beginning of construction, the soil is in a soft, uncompacted state. To ensure that the surrounding buildings or landscape are not damaged if the integrity of the soil is damaged, the foundation pit is strengthened with sheet piling. Most often, sheet piling is installed on large pits.

When constructing a private cottage or house, the need for fencing a pit arises infrequently: if the site has loose unstable soils or construction works begin during the rainy season. Then the soil may begin to wash away into the pit due to precipitation. A high-quality sheet piling will not only help retain soil, but will also retain water.

What is sheet piling

This is a series of piles driven into the ground and forming a fence. The use of such structures allows you to create a safe area for carrying out further work. Often, sheet piling remains in the ground to protect, for example, the foundation from the effects of groundwater.

The tongues are driven into the ground tightly to each other. Thanks to the density of placement and filling of joints with mortar, sheet piling becomes completely moisture-proof.

Types of sheet piling

There are several technologies for installing sheet piling fencing.

Which tongue and groove should I choose?

The choice of piles for sheet piling depends on the future load on the fence. Therefore, you first need to calculate the load, and only then select suitable piles. Then by selection method suitable option: the final option is selected based on price and ease of transportation.

Piles are selected according to the following parameters:

• Durability ─ the service life of metal piles depends on operating conditions; PVC piles are almost eternal.
• Speed ​​of installation - plastic piles are smooth, they have a low coefficient of friction, so installation is 2 times faster than other piles.
• Weight - PVC piles are not heavy, so their loading/unloading and transportation is cheaper.

How to install sheet piling

To install sheet piling fencing during construction on your site, you can rent Larsen sheet piles, which are very convenient for installation. They are easily driven into the ground and just as easily dismantled. However, in order to install Larsen sheet piles, you will need special equipment - a vibrating hammer and a team of 3-4 specially trained professionals. Upon completion of work related to soil strengthening, sheet piles are removed from the ground.

The vibratory hammer can be replaced with a manual vibratory hammer. A manual vibratory hammer is not the cheapest equipment, but if the farm plans to do a lot of work related to driving piles - installing a fence, pile foundation for outbuildings, strengthening the banks of a pond, etc., then you can purchase it. Otherwise, like Larsen sheet piles, you can rent them.

With the help of such a jackhammer with an impact head, the tongues are driven to the required depth. Thanks to the significant impact force of the hammer, the installation time for tongue and groove fencing is reduced and the need for heavy equipment disappears.

Larsen tongue and groove piles are driven into the ground sequentially: the second section is inserted from above into the locking groove of the first section. In this case, it should be rotated 180 degrees relative to the previous one, forming a continuous structure.

How to install wooden sheet piling fencing with your own hands

Can be adapted to strengthen the walls of a pit on quicksand soil unedged board a thickness of at least 4 cm. When installed, such formwork fits tightly together. The boards are fastened with cross bars. If during tongue and groove installation wooden fence the work is hampered by the constant flow of wet soil, it is necessary to use drainage pump. After installing the sheet piling, the soil will remain behind the walls, and the water will flow down to the bottom of the pit.

Beams and corners are installed to connect and strengthen the boards. To ensure the rigidity of the fence from the inside, it is reinforced with spacers made of 10 cm by 10 cm timber. The width of the board for the tongue and groove must be at least 15 cm. The length of the boards depends on the size of the pit. The lower pointed ends of the tongue and groove boards are driven into the ground to the depth of the pit with a sledgehammer.

Despite the apparent simplicity of installation, it is better to dig a pit, choose the type of sheet piles, and install sheet piles with a team of qualified professionals and special equipment.

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