Technogenic soil group. Non-cohesive technogenic soils

General provisions. For the construction of highway subgrades and airfield soil foundations, it is possible to use technogenic soils in all cases where such use provides an environmental or economic effect. Technogenic (artificial) soils include natural rocks that have undergone mechanical processing (waste mining industry); rocks metamorphosed during the combustion of hydrocarbons contained in their composition, including during the production of metal (ash and slag), as well as processed rocks and organic, including artificial, dispersed materials of organic composition (construction waste, non-toxic industrial waste, household waste) .

The new substrates have good plant growth properties such as their nutrient levels, sufficient acidity and stability organic matter in mixtures. In terms of plant yield, the results show that the most high yields obtained in technosols from mixtures where untreated aerobic sludge is used.

Artificial soils, also known as tenosols, technosols or technosoils, are soils made from mixtures of various non-hazardous wastes and by-products. These technologies are usually complemented by other raw materials for their application, both in improving agricultural soils and in restoring degraded areas.

Technogenic soils, as a rule, are not capable of forming fertile soil. Their dumps serve as a source of pollution of adjacent areas with mineral dust and sometimes with toxic substances. In most cases, their storage worsens the environment and makes it difficult or impossible to use the areas for agriculture and housing construction.

On the one hand, the development of mixtures for their production has a dual purpose: on the one hand, the amount of waste is assessed, minimizing the potential environmental impact resulting from poor management of them, and on the other hand, degraded soils are restored without excessive costs.

The idea is to take advantage of all available resources in the market to evaluate them and transform them into the best amendments, fertilizers and techno-technologies needed for optimal management of agricultural soils or for the proper restoration of soil and environmentally degraded spaces. This method also creates wealth and avoids the unnecessary disposal of numerous residues and products that are currently underutilized, suitable for their reintegration into a new life cycle, supporting an environmentally and economically sustainable model that also contributes to the fight against climate change.

The purpose of using technogenic soils in roadbeds may be to reduce the cost of work; clearing the territory occupied by dumps; burial of soils and materials containing toxic impurities; changing the quality of local soils with unfavorable properties using improving additives.

The goal is to create soils of choice and modify agricultural soils in response to various problems. In this project, technologies will be obtained from sewage sludge, which will be complemented by other raw materials, such as sugar foam, mussel shells, coffee and trimmings, as well as other additives.

One of the main innovative elements will be the inclusion of encapsulated bacteria for their beneficial effects in the field: improving fertility due to their ability to fix nitrogen. In short, we believe that the production and use of artificial soils will increase in predominantly agricultural areas, as well as in the garden areas of cities, as they fix atmospheric pollutants and help reduce greenhouse gas emissions into the atmosphere. Another step towards creating a cleaner and healthier environment for everyone.

The replacement of natural soils with industrial waste should be provided for project documentation, and if a replacement is proposed by the builders during the work process, it is agreed with the author of the project.

A feasibility study for replacing natural soils with technogenic ones is carried out according to complex criteria and must contain an assessment of effectiveness in the following areas:

This is some of the most fertile land in the world, but its feature should not be “natural” soil. It was created -800 to 500 from a pre-Columbian civilization that disappeared. Terra Petra is characterized by its black soil, very rich in carbon, ranging from 50 cm to 2 meters in thickness, and its ability to self-renew itself at a rate of 1 cm per year.

However, this land consists of more than just a lump of coal. You would think that modified soil with more or less active carbon would be completely sterile, and coal is known for its germicidal properties. For this land there is a land that is basically alive because more than a thousand microorganisms are involved in the fertility and structuring of the soil.

comparison of transport costs for moving natural soil from designated reserves (quarries) and technogenic soil from dumps (storages);

comparison of the costs of land acquisition for reserves (quarries) with their subsequent reclamation and additional costs of transporting material from industrial dumps, tailings dumps, etc.;

This is probably the reason why current populations ignore the reproducibility of this land and only practice post-deforestation hamlet harvesting, as they cannot hope to produce more than two years on deforestation because the yellow Amazon land requires a plucking period of 8 to 10 years to renew its low production capacity.

It has been shown that with the addition of fertilizer, the yellow soil that became terrata reached 800%. It has even been demonstrated that its soils can remain productive for 40 years without external input. The whole paradox of deforestation exists because if this method of culture were transferred, the "native" would not need to reduce the Amazon to ash in order to survive, the additional deforested areas would remain perennial rather than seeing bare soils and ash being washed away by heavy tropical rainfall.

taking into account the improvement of the sanitary condition of the area due to the elimination of waste containing toxic inclusions and their burial in road embankments;

taking into account the reduction in the cost of production of waste-generating industries by reducing fees for waste disposal;

taking into account the possible technological and structural complication of the roadbed when replacing natural soils with technogenic ones.

In fact, the desire to use terra preta cannot be limited to the poorest soils, since agronomists who only know the fertility of the soil over the years, in the light of our intensive and environmentally unfriendly cultivation regimes, are dying out due to the gradual sterilization of microbial biotopes.

Here the pre-Columbian example demonstrates that this civilization was possible in large quantities, necessary for a large population, for civilization, and not just for agriculture. It is said that this Amazonian civilization living in these black lands was the source of the legend of El Dorado, the land of gold, of course, but also and especially the land of plenty, or everything growing in abundance and without difficulty.

When assessing the suitability of technogenic soils, including industrial waste, the following data must be taken into account: the source of their formation (waste production technology); method of obtaining (from a dump, storage, loading device); composition (mineral, chemical, organic); output state (granular composition - aggregation, density, humidity).

Thus, to promote terra preta as the first means of any will for sustainable production, dead letters must remain. For it is impossible to think about a strong agriculture in the future, losing in methods that reduce the ability of the soil to both produce and provide healthy production and quality.

The progressive expansion of urban areas, often in low-density areas, implies a greatly accelerated process of soil imperviousness due to the constant covering of man-made materials for the construction of buildings, buildings, infrastructure or other artifacts. This is a phenomenon that affects only a part of the settlement, which generally maintains a degree of permeability due to the presence of gardens, urban parks and other open spaces. This phenomenon also includes buildings in agricultural and natural areas outside the traditional urban settlement.

When using industrial, ore and other wastes and by-products, their composition must be checked for the content of toxic and radiation inclusions. If harmful properties are detected, coordination with local sanitary authorities must be carried out.

Waste from coal mining and processing. Waste from the coal industry is divided into waste mine rocks (DMW) and coal preparation waste (CW). Dump mine rocks can be represented by overburden and interstratal rocks that do not contain coal inclusions that affect their properties. In this case, the technology for using OSP does not differ from conventional coarse soils.

Therefore, the indiscriminate spread of artificial land use typologies leads to the degradation of ecosystem functions and changes in ecological balance and should be understood as an environmental cost. The productive functions of waterproofed soils are inevitably lost, as well as their ability to sequester and store carbon, support and support the biotic component of the ecosystem to provide biodiversity or, often, social enjoyment. The area also increases fragmentation and degradation of habitats and ecological networks.

In most cases, CHP is concentrated in industrial waste dumps. Depending on the degree of metamorphism, coal content and storage method in the dumps, spontaneous high-temperature processes occur that change the properties of rocks.

Methods for developing mine dumps correspond to the nature of the deposits. When developing overburden dumps and mine dumps that do not contain coal inclusions, the following rules must be observed: general rules, ensuring high productivity and safety.

In urban areas, loss of vegetation cover and reduction in evapotranspiration, combined with heat generated by air conditioning and traffic, and absorption solar energy asphalt or concrete surfaces, contribute to changes in the local climate, causing the “heat island” effect.

Soil compromised by the expansion of artificial and waterproof surfaces with reduced vegetation and the presence of compacted surfaces can no longer retain and store a good portion of precipitation and thus contribute to the regulation of its surface outflow, with a direct impact on the hydrological cycle and an increase in the frequency and intensity of alluvial and erosion phenomena. Precipitation infiltrated into the soil significantly increases the flow time required to reach rivers, reducing peak flow.

When developing old mine dumps, in which high-temperature processes occurred that led to the burning of rocks, it is necessary to take into account the heterogeneity of their composition. Only non-burning dumps are developed.

The development of dumps with an excavator begins from the upper marks, with a stepped arrangement of the faces from top to bottom. In case of partial removal of the dump, development with a bulldozer and loading into dump trucks with a loader or excavator is allowed.

In addition, severe pressure on urban water resources can lead to changes in the ecological status of watersheds, altering ecosystems and the services they offer. The decline of wetlands, natural wells, and permeable soils, coupled with urban expansion on floodplains and coastal plains, often located along coastlines or riverbanks, increases the risk of flooding, also considering possible consequences additions to climate change.

Flooding of soils and artificial surfaces by surface water and increasing runoff rates also lead to increased solid loads and contaminant levels, which have a strong impact on the quality of surface water and aquatic life, especially when the first rainwater is not properly treated, with its additional pollution load that, during dry periods, is deposited in the mixed sewers that characterize most of our urban areas.

At high soil temperatures, as well as during heavy dusting, development is carried out with simultaneous watering using hydraulic equipment high pressure.

It is advisable to transport burnt rocks and burnt rock mixtures to the highway in the autumn-winter period, store them on the right-of-way in a layer no more than 1.0-1.5 m thick, and carry out the embankment construction work in the spring-summer period. The impact of precipitation, temperature changes, and freeze-thaw cycles in a layer of unconsolidated rock contributes to the destruction of non-water-resistant low-strength inclusions. When using lightly burned and unburned rocks, it is recommended to cyclically soak and dry them, which leads to the destruction of weak inclusions.

It should be added that the deterioration of the territory also occurs where there is no direct change of the soil, because non-artificial transitions, however, are difficult to restore and many soil functions are blocked. Therefore, considering the influence of artificial covering of part of the soil on indirect effects and disturbances, the availability of free and quality soil is further compromised.

Community guidelines and conservation of soil consumption in Italy. . This strategy places an emphasis on preventing further land degradation and maintaining its functions, emphasizing the need to implement best practices to reduce the adverse effects of soil consumption and, in particular, its most obvious and irreversible form: waterproofing.

In order to maximize the destruction of non-waterproof low-strength inclusions, the work technology should provide for two-stage compaction with mixing. On first stage compaction with crushing is carried out with heavy lattice rollers weighing 25-30 tons or cam vibratory rollers weighing more than 17 tons. The number of roller passes depends on the initial content of fine earth and is approximately 4-6 passes for unfired rocks and 5-8 for lightly burned rocks. The final number of passes is determined by trial compaction. To ensure uniform distribution of fine earth throughout the thickness of the layer, after the first stage of compaction, it is loosened and mixed with rock.

Next year also outlines action priorities and guidelines to be followed to achieve this goal by defining action strategies to limit, mitigate and compensate for soil waterproofing. In other words, Member States will have to prioritize limiting waterproofing by reducing the conversion rate and conversion of agricultural and natural land and reusing already urbanized areas by setting realistic targets for soil consumption at national and regional levels and in activities such as the concentration of new urban development in designated areas.

Second phase compaction is carried out after additional humidification by the amount of evaporation losses. At the second stage, compaction is carried out with heavy rollers on high-pressure pneumatic tires weighing 25-30 tons or smooth drum combined rollers. The approximate number of roller passes along one track is 8-12. When compacting burnt rocks and burnt rock mixtures, the greatest effect is achieved by vibrating rollers weighing 8-12 tons with 4-6 passes along one track or vibrating tamping machines with 2-3 passes.

Only when soil loss is unavoidable can mitigation measures be put in place to maintain essential soil functions and reduce negative environmental impacts. Finally, all the inevitable new measures to underground waterproofing must be compensated, for example, by requalifying already waterproofed lands or, in as a last resort, in the form of economic fees, provided that they will be required to use them in soil protection measures. The Community Guidelines, the growing awareness of the ecological importance of soils and land and the need to counteract its progressive degradation while ensuring the restoration of the ecosystems it guarantees, have led to a number of normative proposals for guidance in last years sustainable and protective of Italian soils, mainly aimed at curbing soil consumption, protecting agricultural and natural areas and promoting the reuse and regeneration of already urbanized areas.

The first stage of compaction-crushing can be omitted by introducing the required amount of fine earth into the rock composition and thoroughly mixing the mixture. Sandy and sandy loam soils, flotation waste, crushing waste, and slag screenings can be used as fine aggregate.

In order to protect softened materials from weathering on the slopes and at the base of the embankment, the design may provide for the installation of protective layers. As each layer of waste embankment is erected, a layer of cohesive soil of the same thickness is added to the slope side, giving the surface of the slope an appropriate slope. The compaction of the protective layers is carried out simultaneously with the compaction of the waste layer.

Technogenic soils, consisting of fragments of varying strength and water resistance, are divided into 4 types according to their aggregate strength (Table 17).

Table 17

Note. Aggregate strength A is characterized by the amount of residue on a 2 mm sieve after wet sieving of a material sample compacted in a Soyuzdorniy standard compaction device in a water-saturated state: A o - for a sample that is not subjected to soaking-drying; A 3 - with 3 cycles of soaking and drying; And 10 - the same, for 10 cycles

When using technogenic soils for the construction of a roadbed, the most appropriate work scheme is to obtain coal waste from the storage bins of processing plants and transport them to the construction site using the company's vehicles.

After hydraulic enrichment, the moisture content of coal preparation waste (COW) is 8-14%, which may be close to optimal. When humidity exceeds the optimum by 3% or more, it is necessary to take measures to reduce it by drying or adding drier soil from waste heaps or mines. When using waste after pneumatic beneficiation methods, its moisture content is close to the initial moisture content of the coal-bearing seams (1-4%), therefore such OS require additional moisture to the optimum moisture content before compaction.

When compacting conditionally aggregate-strong OUs, it is necessary to achieve a dense structure in which the voids between the fragments contain 30-40% (or more) of fine-grained aggregate. This prevents possible subsidence during the destruction of large fragments. An increased content of fine soil is achieved by adding the missing amount of fine soil or by destroying large fragments.

When constructing protective layers from cohesive soils it is possible to leave waste with a reduced content of fine earth in the core of the embankment. In this case, for conditionally aggregate-strong type 1 OSs, the most rational option is the two-stage compaction technology. As a result of the first stage of compaction, a significant amount of fine earth is formed in the upper part of the layer (layer up to 10 cm), which can serve as material for the protective layer. This layer is moved by a bulldozer to the slope part of the embankment and then, after leveling, the second stage of compaction of the entire layer is carried out.

Waste fuel combustion- these are ash and slag from thermal power plants (fly ash, ash from oil shale, coal, peat), including from dumps. Fuel combustion waste can be used in the roadbed and soil foundations both with and without binder reinforcement.

For large-scale use of ash and slag mixtures from industrial dumps, a complex must be carried out preparatory work, consisting of laying access roads, face equipment, power supply for lighting, water supply, household and sanitary facilities.

On dry ash and slag dumps, an important operation is the systematic watering of the developed massif. For irrigation, it is advisable to use high-pressure equipment, which provides a larger area and more uniform wetting.

When developing ash and slag dumps for hydraulic transportation, it is necessary to take into account the technological segregation of slag during the reclamation process. Based on the requirement of homogeneity of the rock type across the backfilled layers in the work execution plan (WPP), the priority for developing the material is determined according to individual maps, within which it is relatively homogeneous.

Development and loading of ash and slag mixtures into dump trucks is carried out using a tractor loader or single-bucket excavator. In dry weather, the face and loading area should be systematically irrigated with water to suppress dust. It is advisable to carry out the development of dry dumps in winter.

Compaction of ash and slag mixtures is carried out using heavy pneumatic rollers with preliminary rolling with rollers weighing 4-6 tons. The use of vibration compaction is effective.

The number of roller passes and the need for additional moisture are determined by trial rolling.

Chemical and household waste. In the lower layers of embankments, the use of solid waste from metallurgical, energy, and chemical production (sludge, slag, cinders, etc.) is allowed, taking into account the established sanitary restrictions. At the same time, the possibility of removal of soluble compounds by precipitation and runoff water is prevented by the use of protective layers of clay soil at the base of the embankment, on its surface and slopes. The thickness of the protective layers is established by the project from the condition of practically preventing filtration.

Solid household waste, ash from burning household waste can be placed in the lower part of the embankment in compliance with established sanitary restrictions regarding proximity to sources and water intake areas, boundaries of populated areas, etc. The construction of protective layers of clay soil in these cases is mandatory.

Solid chemical and household waste is laid in layers, the thickness of which is determined by test compaction, based on the absence of subsidence of the surface under the drum of a heavy roller. The protective layer on the slopes is laid simultaneously with the layers of waste to the appropriate thickness. Compaction with rollers is carried out over the entire surface of the layer, including protective layers on slopes.

When using solid household waste of high porosity (containing paper, containers, etc.) and the impossibility of rolling it to a sediment-free state, a closing layer of soil 30-50 cm thick should be created and compaction should be carried out with a heavy falling load.

Use of ash materials. According to the method of removing fuel ashes and slags from places of accumulation in steam power units, they are divided into dry selection ash, ashes and slags of separate and joint hydraulic removal. With the joint hydraulic removal of ash and slag in dumps, they form technogenic heterogeneous masses of material called ash and slag mixtures.

Depending on the type of fuel burned, ash materials are divided into lignite, coal, peat and oil shale.

Dry fly ash is a fairly homogeneous material in its chemical and granulometric composition, while possessing a certain chemical activity. It is advisable to use them in the construction of subgrades from soils of high humidity as an additive for their drainage and improvement.

Due to hydration, hydraulic removal products lose their chemical activity, especially free calcium oxide and other compounds that provide independent hardening.

Ashes and ash and slag mixtures have a number of advantages compared to soils, analogues of which they are in certain cases. They can be used either independently for the construction of a subgrade or for draining (as dry inert additives) structural layers from soils of high humidity.

Inactive ash, as well as ash and slag mixtures, do not have astringent properties and contain almost no clinker materials. Their hydraulic module is less than 0.05; The pH of the aqueous extract lies in the range of 4.5-11.5. The main indicators by which their use in embankment structures is regulated are indicators of composition and condition. Based on these indicators, ash and ash and slag mixtures as technogenic formations are classified as analogues of the corresponding types of soil (GOST 25100-95) and requirements are imposed on them SNiP 2.05.02-85.

Ash and slag mixtures have a very different granulometric composition: from fine to crushed. Their chemical and mineralogical composition is also different. Therefore, in certain cases, ash and slag mixtures are recommended to be used in the roadbed instead of sandy soil or sand-gravel mixtures.

The use of ash materials in subgrade structures is carried out on the basis of a comprehensive geotechnical and technological assessment. In accordance with this assessment, the places of their selection are determined for a specific source of ash materials; carry out their classification according to their soil analogues; establish in the laboratory the corresponding standard compaction curves and use them to adjust the values and range of permissible humidity levels; perform an assessment based on the degree of heaving and swelling. The degree of heterogeneity of these materials is established on the basis of statistical processing of indicators of physical and mechanical properties, primarily in terms of composition and condition.

When developing a project for the construction of a roadbed from ash materials, the following recommendations are adhered to. The working layer must be constructed from non-heaving and non-swelling types of ash or ash and slag mixtures. The low density of particles of ash and ash and slag mixtures, as well as very low adhesion values, determine the significant tendency of slope parts made from the materials under consideration to erosion as a result of erosion, and therefore the steepness of the slopes should be no more than 1:2, and the thickness of the fertile or protective layer on them the surface is increased accordingly to 0.2-0.5 m. Technological operations for leveling the surface of slopes or installing protective layers before sowing grass should be carried out immediately after the construction of the embankment with minimal interruptions.

When constructing embankments from ash and slag mixtures on terrain of types 2 and 3, according to moisture conditions, it is recommended to carry out the following measures: in type 2 terrain, the lower part of the embankment to the height of flooding must be constructed from draining soils in the form of a capillary-interrupting layer; in areas of the 3rd type of terrain, provide for the installation of a berm at the bottom of the embankment with a width of at least 1 m in order to protect the slope parts of ash and slag mixtures from flooding by long-term standing waters.

Preparatory work for the construction of embankments from ash and ash and slag mixtures includes the preparation and testing of ash dumps, the installation of temporary drainage, communications for the movement and settling of construction vehicles, the organization of places for stacking ash materials if they need to be stored or dried; performing input control elements to assess geotechnical properties and compare them with design data; preparation of plant or clay soil for the installation of protective layers on slopes and roadsides.

The development of dumps or ash material reclamation maps is carried out using excavators with any type of bucket equipment, and the soil is transported by dump trucks. Transportation and unloading are carried out on a prepared base or on pre-filled and planned soil layers (provided for by the project).

The maximum permissible moisture content of ash and slag mixtures for the passage of construction vehicles is (1.35-1.40) W wholesale

Filling is done in layers using the “pull” method. It is recommended to carry out leveling with bulldozers layer by layer with a layer thickness of 20-80 cm, depending on the type of roller used for further compaction and the results of test rolling. When using filling using the “longitudinal transportation” method, leveling is carried out with a heavy motor grader. The thickness of the layer of loose ash and slag mixture should be 1.1-1.3 times greater than the design one, respectively, for dusty and coarse-grained mixtures.

The layer of ash and slag mixture is compacted at optimal humidity or close to permissible humidity.

Depending on the natural moisture content of the ash and slag mixture placed in the embankment, it must be dried or moistened to a moisture content close to the permissible one. Drying of ash and slag mixtures is carried out by loosening and mixing with a bulldozer or motor grader, adding layers of dry sandy soil, adding quicklime or active ash additives. Drying of ash materials can also be carried out directly at the places where they are received by preliminary development into a dump under favorable climatic conditions, and by installing drainage structures. Additional moistening of the ash and slag mixture layer is carried out immediately before compaction with a watering machine.

After the construction of an embankment of ash and ash and slag mixtures, the top layer must not become over-dry and dusty. To do this, it is recommended to lay a closing layer of soil 10-20 cm thick, strengthening the slopes with a layer of vegetable soil with sowing grass or another type.

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Features of designing the foundations of structures erected on technogenic soils

Tman-madeeprimings - natural soils and soils modified and displaced as a result of industrial and economic activity . Tman-madeeeducation - solid waste from industrial and economic activities, as a result of which radical changes in the composition, structure and texture of natural mineral and organic raw materials occurred.

Most artificial soils are confined to industrial and urban areas and are formed as a result of military operations.

Technogenic soils are used as grounds buildings and structures, as well as material for construction various engineering structures(earth dams, road embankments and railways etc.). The volume of technogenic deposits in various structures is measured in hundreds of billions of cubic meters: during mining, processing and combustion solid fuel every 5 years, about 40 billion m 3 of waste (for open-pit mining - overburden) rocks and 2 billion m 3 of ash and slag are placed in dumps; out of 100 kg of extracted raw materials, 99 kg are returned to the environment as waste.

Engineering-geological properties technogenic soils are determined by the composition of the parent rock or waste from industrial and economic activities and the nature of human impact on them. In accordance with the generally accepted classification of soils GOST 25100--95 "Soils. Classification", technogenic soils are allocated to a separate class.

Classification of technogenic soils includes six taxonomic units, distinguished according to the following groups of characteristics:

Class - (rocky, dispersed, frozen) according to the nature of structural connections;

Group - (rocky, non-rocky, connected, disconnected, ice) according to the nature of the structural connections (taking into account their strength);

Subgroup - (natural formations altered under natural conditions; natural displaced formations altered by physical, thermal, physicochemical effects; bulk, alluvial, altered by physical (thermal) etc. effects) - by origin and conditions of formation;

Type - according to material composition;

Type - by soil name (taking into account particle sizes and property indicators);

Variety - according to quantitative indicators of the material composition and structure of soils.

This classification is not without shortcomings and requires clarification.

Cultural layers - formation of a unique composition, determined by the geological conditions of the area and inclusions, which are determined by the nature of economic and cultural activities. They have a heterogeneous composition in area and vertically; with the growing scale of urban planning and urbanization, they are widely involved in construction practice. Construction on multi-meter cultural layers requires, during engineering and geological surveys, the development of methods and instruments that will allow construction in the areas of dumps of construction waste, household and industrial waste. Construction is prohibited in the territories of old cemeteries; as well as at cattle burial grounds.

Natural displaced images calling - natural soils removed from their natural locations and partially subjected to industrial processing in this process. They are formed from dispersed cohesive and non-cohesive soils. Rocky and semi-rocky soils are first subjected to crushing and move as dispersed coarse-clastic soils. The same applies to class frozen soils. According to installation methods they are divided into bulk and alluvial.

Bulk soils According to educational technology, they are divided into planned and unplanned dumping (construction and industrial). To bulk construction include soils of embankments of roads and railways, dams and dikes, embankments under the foundations of buildings and structures, soils backfill during the construction of underground linear structures. To industrial - mined rocks of the mining industry, overburden rocks, rocks from mine workings.

They are formed from the soils of neighboring excavations or from material delivered from specially laid pits, quarries and cuts to the construction site.

The engineering and geological features of the soils of embankments and dumps include:

Disturbance of the soil structure in the body of the embankment, causing a decrease in strength (compared to its natural occurrence);

Soil fractionation and self-leveling of dump slopes;

Change in strength over time (shear resistance increases due to compaction or decreases when the embankment is moistened);

The appearance of pore pressure in water-saturated clay soils of the embankment, which is a factor in the development of landslides of various types.

In the process of preparing soils for excavation and during excavation and loading, transport and dumping operations, they are loosened. The coefficient of sand loosening (the ratio of density in natural conditions and in the embankment) is 1.1--1.25; for clays it can increase to 1.6.

Depending on the lithological composition there are homogeneous and heterogeneous embankments. The heterogeneity of the embankment can be caused by the natural fractionation of soils during their filling. In this case, small and large fractions are concentrated in the upper and lower parts of the embankment, respectively. This type of embankment also occurs when dumping soils of heterogeneous composition, such as sand and clay. The sandy mass is concentrated in the upper part of the embankment, and pieces and lumps of clay roll down. The same thing happens when sand contains inclusions of coarse material.

Strength characteristics of bulk soils must be determined taking into account the conditions for the formation of bulk slopes, the service life of which is usually short. Therefore, when calculating the stability of an embankment, the base or body of which is composed of clayey water-saturated soils, one should take into account the incomplete compaction of soil masses, assessed from the results of shear tests clay soils for various stages of compaction.

The influence of the time factor on the condition of the embankment soils is reflected in the acquisition of compaction and cohesion by these soils. The amount of “secondary” adhesion depends on the composition of the rocks, the time of existence of the embankment and the strengthening load.

Time for soils to acquire natural density

Alluvial soil - are created by means of hydromechanization using a pipeline system. Perform organized and unorganized alluviums. With organized Alluviums, which are carried out for engineering and construction purposes, create soils with predetermined properties. This is how high-density layers of sand are washed, intended to serve as the foundation of buildings and structures, medium-pressure dams and dikes, and road embankments. When unorganized in alluvium, the problems of moving soil to free up working areas are solved (stripping work in mineral deposits and building materials).

The construction of ground structures and territories using hydromechanization methods includes:

Hydraulic development of soil (dredgers, hydraulic monitors);

Hydrotransport of soil (through main and distribution pipelines);

Alluvium of soil into earthen structures or alluvial areas.

Engineering-geological properties A alluvial soils are determined by their composition and the physicochemical interaction of mineral particles with water. The composition of the soil in a hydraulic dump depends on the composition and conditions of occurrence of the rock in natural conditions, technological factors (method of hydraulic stripping operations; method of releasing hydraulic mixture onto the alluvial map; intensity of alluvial work) and chemical composition pore waters. The properties depend on physical and geographical factors - bed topography and climate, engineering and geological properties of the soils at the base of the alluvial structure - the composition, condition and properties of the soils underlying the alluvial structures.

Compound mineral and organic components of alluvial soils determines the nature of structural bonds and the time they acquire specified physical and mechanical properties. During alluvium, the hydraulic mixture (water-soil) is divided into fractions. Coarse particles are concentrated near the outlet of the hydraulic mixture, i.e., where the near-slope (beach) zone is formed, predominantly fine sandy silty particles make up the intermediate zone and the finest (clayey and silty) particles form the pond zone of the hydrofill structure.

Highlight three stages of formation of properties of alluvial soils: compaction, strengthening and stabilized condition.

After the formation of alluvial soils - sedimentation associated with the precipitation of mineral particles from the flow of hydraulic mixture entering the alluvial map, the soil is in a state close to complete water saturation and has a very loose composition (degree of water saturation Sr alluvial sands in this case does not fall below the value of 0.8) - begins compaction stage. Increased density is achieved through gravitational compaction; filtration compression of soil in the process of intensive water loss; capillary-meniscus compression of the soil under the influence of capillary pressure. During this period, the main part of the self-compaction of alluvial soils occurs. For most alluvial sands, the duration of the stage does not exceed 1 year.

Hardening stage characterized by the continued acquisition of strength properties of alluvial soils due to infiltration compression of sand and static pressure of the upper tiers of alluvium and clogging. Various types of cementation bonds arise between the particles, and increased strength and dynamic stability are acquired. The duration of the stage is from 1.5 to 3 years.

At the stage of stabilization soil strengthening continues to develop due to the formation of water-resistant cementitious bonds. The process is fading. At the end of the stage, alluvial sands already belong to the category of significantly strengthened ones and, according to strength data, are close to late Quaternary alluvial sands. The duration of the stage reaches 10 years or more.

Techn. genic formations - solid waste from industrial and economic activities, as a result of which there was a radical change in the composition, structure and texture of natural mineral or organic raw materials. These include: household waste, concentrating on city and town landfills, and industrial waste, including construction waste, slag, sludge, cinders, cinders, etc.

The formation is associated with the geological and geomorphological conditions of the area, with the history of the city or town, with characteristic industrial, economic and cultural activities. Technogenic formations are specific soils, the study of which should take place using a combination of engineering-geological, historical-archaeological, technological and geoecological research methods.

The accumulation (storage) of formations occurs due to the dumping or alluvium of various garbage (formation of a “cultural layer”), in specially designated areas for city dumps of solid household waste and construction waste, in filtration fields, within the tailings of large industrial enterprises (metallurgical plants, thermal power plants and thermal power plants, mining and processing plants, etc.). Due to this by accumulation method technogenic formations are divided for bulk, alluvial and frozen(in harsh climates and in areas where permafrost occurs).

Technogenic formations have a unique composition that is formed in the process of their accumulation. For most urban landfills, there is extreme heterogeneity of composition in the vertical and horizontal directions, and great variability in thickness along strike (from a few centimeters to 15-20 m). For bulk and alluvial formations in tailings ponds, the composition of sediments can be highly homogeneous (slag, ash, etc.).

Basic engineering-geological properties technogenic formations depend on their mineralogical and granulometric composition, depth (thickness), presence or absence of organic residues, water saturation, mineralization groundwater, duration of existence, relief and nature of the natural underlying soils. It is difficult to erect buildings and structures on the soils of household dumps. In recent years, technologies have been developed for the reclamation of solid waste landfills, eliminating uncontrolled emissions of biogas and toxic leachate. This will make it possible to effectively use the areas alienated for landfills. What all soils have in common is underconsolidation, water saturation, and the ability to be highly compressible.

Approximate time periods required for natural compaction various types technogenic formations: 1) slag dumps, molding soil, waste from processing plants, ash, depending on the composition - 10-20 years; 2) landfills for waste from various industries and household waste, depending on the composition - 10-30 years.

The soils of any technogenic formations, especially large-scale ones, cause various loads on the geological environment, in many cases change the conditions of its “life” and, interacting with other geospheres, can lead to a disruption of the equilibrium state of the geological environment and cause undesirable environmental changes.

When storing and constructing structures, the complex task of predicting the engineering-geological and hydrogeological conditions of the territories allocated for their storage, changes in the properties of these soils over time, the activation or occurrence of unfavorable engineering-geological processes, and the development of optimal measures for the protection of the natural environment should come to the fore.

Environmental protection schemes vary and largely depend on the right choice places of their storage. They should be optimally placed:

In areas with engineering-geological and hydrogeological conditions that require the least cost for environmental protection measures;

Below places of drinking water intakes; fish farms and fish spawning areas;

On lands not suitable for agriculture, industrial and civil construction.

Improved soils. Natural soils whose properties have deteriorated during the process construction work(artificially loosened, moistened, etc.) are called deteriorated soils. The properties of soils, mainly strength and deformation characteristics, can be artificially changed for the better with the help of technical soil reclamation. In this case they are called improved soils.

Improvement of soil properties is carried out under natural conditions or after appropriate processing and subsequent placement, for example, in the base of an object. Each improved soil has predetermined properties and becomes quite suitable for solving construction problems. For industrial and civil construction, improved soils are most often used as foundations for buildings and structures. Improved soils are most widely used in the construction of objects on permafrost and subsiding loess soils.

Foundations composed of bulk soils must be designed taking into account their significant heterogeneity in composition, uneven compressibility, the possibility of self-compaction, especially under vibration influences, changes in hydrogeological conditions, soaking, and also due to the decomposition of organic inclusions.

In bulk soils consisting of slag and clay, it is necessary to take into account the possibility of their swelling when soaked with water or chemical waste from production.

The uneven compressibility of bulk soils should be determined based on the results of field and laboratory research, carried out taking into account the composition and composition of bulk soils, the method of filling, and the removal of material constituting the main part of the embankment. The deformation modulus of bulk soils, as a rule, should be determined on the basis of stamp tests.

The total deformation of the foundation should be determined by summing the settlement of the base from the external load and additional settlement from the self-compaction of bulk soils and the decomposition of organic inclusions, as well as the settlement (subsidence) of the underlying soil from the weight of the embankment and loads from the foundation.

Preliminary dimensions of foundations of structures erected on compacted bulk soils may be assigned based on the values of the calculated resistance of the foundation soils R0.

If the calculated deformations of the foundation composed of bulk soils are greater than the maximum or the foundation’s bearing capacity is insufficient, the following activities are envisaged :

Surface compaction of foundations with heavy tampers, vibrating machines, rollers;

Deep compaction with soil piles, hydraulic vibration compaction;

Construction of soil cushions (sand, crushed stone, gravel, etc.);

Cutting through bulk soils with deep foundations;

Constructive activities.

Foundations composed of alluvial soils , should be designed taking into account their heterogeneity (multilayers, variability of composition and properties in plan and depth), the ability to change physical and mechanical properties over time, including due to fluctuations in groundwater levels, sensitivity to vibration influences, as well as possible sediments of the underlying layers.

As a rule, sandy soils should be used for reclamation.

Alluvium of soils on subsidence (in soil conditions of type I), swelling and saline soils is permitted with appropriate justification.

Strength and deformation characteristics of alluvial soils, as a rule, should be established based on the results of field and laboratory studies of undisturbed soils, taking into account the age of the alluvial soil, i.e. the time elapsed after the end of alluvium, as well as the time difference between the period of engineering and geological surveys and the start of construction.

For preliminary calculations of foundations, as well as final calculations of the foundations of buildings and structures of class III, it is allowed to use the values of the strength and deformation characteristics of soils obtained from their physical characteristics depending on the age of alluvial soils.

Calculation of foundations composed of alluvial soils must be carried out in accordance with the requirements of Section. 2.

If the thickness of alluvial soils is underlain by biogenic soils or silts, in the calculations of the foundations the requirements of Section. 5. In this case, use columnar foundations not allowed.

Values of strength characteristics of alluvial soil ( II and c II) should be taken as appropriate for the start of construction.

The complete deformation of the foundation composed of alluvial soils should be determined by the summation of the settlement of the foundation due to external load, self-compaction of the thickness of alluvial soils and additional settlements due to the incomplete consolidation of the underlying soil layers loaded with alluvium. man-made reinforced soil

When the calculated deformations of the foundation composed of alluvial soils are greater than the maximum or the bearing capacity of the foundation is insufficient should be provided:

Compaction of alluvial soils (vibrating machines and rollers, deep hydraulic vibration compaction, use of explosion energy, compaction, excessive soil alluvium in the building area, etc.);

Fixing or reinforcing alluvial soil;

Constructive activities.

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Technogenic soil group. Non-cohesive technogenic soils

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