Determination of kinematic and geometric parameters of multi-scraper chain trange excavators on the basis of the semi-blocked critical depth regime of soil cutting

Trench excavators with a chain-scraper working body became widespread in the construction of linearly extended objects. Increasing workloads and rising energy prices call for optimizing the parameters of construction machinery. The most important component of the process of digging the soil with a chain-scraper working body is cutting the soil with scrapers (knives).When calculating the cutting forces, the working body is taken as a complex mechanical system of traction chains and transverse beams, on which in a certain order are arranged and fixed scrapers-knives with known angular parameters. Separation of chips from the soil is carried out by each scraper in the conditions of blocked, semi-blocked and free cutting of the soil. It should also be borne in mind the change in resistivity and energy consumption of soil cutting with a change in chip thickness. The minimum energy consumption of soil destruction takes place at a critical depth of cut. To reduce the energy consumption of the soil destruction process, a method of calculating the parameters of chain-scraper working bodies of trench excavators is proposed, which is based on critical depth cutting of soils. The initial data for the calculation are: technical productivity, m3 / h; maximum trench depth, m; trench width, m; physical and mechanical characteristics of soils (coefficient of adhesion, specific gravity, angles of internal and external friction). The proposed calculation method allows to determine the technological and geometric parameters of the chain-scraper working body with critical depth cutting of soils.

Stress-strain state of a borehole determined analytically using drilling-out as a technology of reducing differential settlement

The existing approaches for reducing the differential settlements of buildings and structures have their own advantages and disadvantages. Lowering of a building or part of it is one of the promising methods to reduce the differential settlements of shallow foundations resting upon weak silt-loam soils. The effect is achieved by drilling-out vertical boreholes in the immediate vicinity of the foundation from the minimal settlements. Method: Russian and foreign scientists have been involved in the development of calculation procedures for horizontal and inclined drilling-out of boreholes. It has been important to determine drilling parameters when using this technology and how soil characteristics and stress state of soils around the borehole influence the reduction of differential settlements. The paper discusses the influence of the strength characteristics of soils on the stress state of the soil massif around the borehole, as well as the influence of the borehole radius on the formed areas of limit state. The analytical solution is based on the well-known ratio used to determine the stress state around the borehole during pressure tests. Tangential and radial stresses are determined from this ratio; next, they are checked according to the condition of the strength law, and thus, the stress state around the borehole becomes evident. Result: The stress state of the soil around the boreholes has been calculated by the given method; it has made it possible to calculate the areas of soil destruction and determine the parameters of boreholes and their geometry depending on the purposes when regulating the settlements of slab foundations. It has been established that drilling behind the foundation contour in relation to drilling in the foundation contour makes it possible to increase the radius of the plastic deformation zone up to two times under the same soil conditions and well geometry.

Сomparative analysis of efficiency of use a screw drill on frozen soil

Introduction. Drilling of frozen and permafrost soils is one of the complex and energy-intensive processes of earthworks. Drilling tools used on frozen soils implement the process of drilling the soil by deformation of cutting or crushing action. Current drilling tools are not efficient enough to use because they implement energy-intensive drilling processes and are not always suitable for various types of soils. A screw drill is considered, which implements the process of soil destruction by shear and shear deformation, which is less energy intensive.Materials and methods. On the basis of theoretical studies of the interaction of 3 types of drilling tools with frozen soil, a comparative analysis was carried out to determine the efficiency of a screw drill use. The technical and economic indicators of the drilling process were compared. A method for determining the efficiency of the use a screw drill based on the analysis of special target functions is presented.Results. The results of a comparative analysis of drilling tools have been obtained. Depending on the nature of soil deformation, the effectiveness of one drilling tool over another is determined. As a result of a comparative analysis of the drilling speed and the energy intensity of the drilling process, the efficiency of the screw drill was established.Discussions and conclusion. In the course of the comparative analysis, the efficiency of the screw drill was determied, which implements shear deformation and soil separation, justifying the feasibility of further research.

Determination of the regularities of the soil punching process by the working body with the asymetric tip

The presence of analytical dependencies describing the process of static soil puncture by a working body with a conical asymmetric tip is necessary to create installations with the ability to control the trajectory of the soil puncture. The paper considers the features of the process of interaction of an asymmetric conical tip with the ground. Analytical relationships were obtained to determine its reactions during a static puncture, the deviation of the head trajectory from a straight line, to determine the size of the soil compaction zone and the magnitude of the destructive force that acts on adjacent communications and other underground objects. It was found that with an increase in the value of the displacement of the top of the cone, for example, from its axis from 0.02 m to 0.08 m with a borehole diameter of 0.2 m, the value of soil resistance increases almost four times. The greatest resistance is achieved when piercing a hard sandy sand. It was found that with an increase in the displacement of the tip of the tip cone, the deviation of the trajectory increases. The piercing head achieves the greatest deviation from the straight trajectory of movement with a sharper cone and a greater asymmetric deviation of its top, and, for example, in hard sandy loam can be up to 0.17 m with a span of 10 m. It was found that the size of the soil destruction zone will be almost 1.8 times larger than the tip in the form of a symmetrical cone and reaches from 8 to 12 borehole diameters, depending on the type of soil. The maximum pressure on adjacent objects can reach from 0.06 MPa in hard-plastic clay to 0.09 MPa in hard sandy loam. The calculated dependences obtained for determining the power and technological parameters depending on the geometric dimensions of the asymmetric tip of the working body can be used to create installations with a controlled static puncture for use in the most common soil conditions.

Reducing the soil structure destruction along the rut and increasing the traction properties of the tractor by using the rear grouser of the track link

The traditionally used mixed grouser of the metal track link causes a decrease in the traction qualities of the agricultural tractor. The use of a rear grouser on the track link, in our opinion, will significantly improve the traction properties of an agricultural tractor with a metal track and reduce the soil destruction. When the rear grouser is immersed in the soil, an additional horizontal deformation of the soil occurs, which changes the law of horizontal deformation distribution along the support surface of the trackdrive, which ensures the alignment of the link shares in the implementation of the tangential traction force. This leads not only to a reduction in the trackdrive skidding, but also to a reduction in tractor rolling losses. Comparative tests of the T-4A tractor with a serial track, and a track on which links the front grousers were removed showed that the maximum traction power increases from 59 to 65 kW, the skidding with a hook load of 40 kN decreases from 14.6 to 9.4%, the rolling resistance coefficient decreases from 0.093 to 0.072, eliminates the “scissors” effect, which will reduce the number of erosive-dangerous particles in the track trace to 30...40%, which is 5.6...4.25 times less than in agricultural tractors with a mixed grouser, which confirms the effectiveness of their use.

Analysis of research on soil destruction criteria during its interaction with working bodies

Under the action of the working surface of the tillage unit, three mutually perpendicular stresses and corresponding deformations occur in the soil layer, which are characterized by different time functions. The finding of these functional relationships is the fundamental task of agricultural mechanics, with the help of which the process of soil crumbling with different physical and mechanical properties can be described in interaction with working bodies. The article presents an analysis of the results of studies of domestic and foreign scientists of the process of soil destruction in its interaction with working bodies. When considering the process of soil destruction from the point of view of stress theory, the Coulomb-Mohr theory of destruction is most often used. It is proposed to expand the consideration of the process of soil destruction by adding elements to the theory of strength that will describe the rate of change of the acting loads.

THE ANALYTICAL DETERMINATION OF THE PARAMETERS OF THE WELL WHILE ELIMINATING UNEQUAL SETTLEMENT OF FOUNDATIONS METHOD OF DRILLING-OUT OF THE SOIL

Existing approaches which allow to reduce the settlement unevenness of buildings and structures have their own advantages and disadvantages. One of the promising methods for reducing shallow foundations the settlement unevenness, which are based on soft dust and clay soil, is the building or its part lowering. The effect is achieved by drilling vertical wellbores in the immediate proximity to the existing foundation from the side of the least settlement. At different times, domestic and foreign scientists were engaged in to the methods of horizontal and inclined drilling of wellbores, an important issue, when applying this technology, is the determination of drilling parameters, the influence of soil characteristics and the stress state of the soil around the well, on the roll reduction process. The article considers the influence of the soil strength characteristics on the stress state of the soil which are surrounding the wellbore, and the effect of the drilled wellbore radius on the formation of the critical state regions. The analytical solution is based on the use of the well-known relationship for determining the stress state around the well during pressiometric tests. From this ratio, tangential and radial stresses are determined, which are then checked according to the condition of the law of strength, thereby forming a picture of the stress state around the well. According to the presented methodology, the stress state of the soil around the wells was calculated, which allows calculating the zones of soil destruction and thereby determining the parameters of the wells and the geometry of their location depending on the goals, when regulating the sediment of slab foundations.

The Mathematical Model of Forestry Machines Impact on Cryolitozone Forest Soils

In the Russian Federation, the permafrost zone are gaining increasing importance due to wood procurement operations. Active timber harvesting, accompanied by the simultaneous development of wood processing enterprises in the Far Eastern Federal District, leads to the depletion of available and exploitable forests in southern and central Siberia, Buryatia, and Khabarovsk territory. The exploitation of modern forestry machines, wheeled forwarders, in particular, broadens the question of their effectiveness. In specific production and geotechnical conditions, the cross-country ability and technological productivity of wheeled forwarders are of particular relevance. These circumstances, combined with the need to minimise technological pressure on the ecological environment raise the problem of optimisation of the forest machines. We developed a mathematical model for calculating parameters of the defrosting soil destruction process occurring at the border with the permafrost zone. The mathematical model allows assessment of the possible value depth of the induced track at the stage of the project design. The assessment is conducted with the account of the forest machine’s technical and maneuvering capabilities in specific natural and industrial conditions.

Mapping the Recovery Process of Vegetation Growth in the Copper Basin, Tennessee Using Remote Sensing Technology

The Copper Basin (CB) of southeastern Tennessee, known as the Ducktown Mining District, is a classic example of forest and soil destruction due to extensive mining and smelting operations from the mid-1800s until 1987. The smelting operation released a sulfur dioxide by-product that formed sulfuric acid precipitation which, in combination with heavy logging, led to the complete denudation of all vegetation covering 130 km2 in CB. The area has since been successfully revegetated. This study used remote sensing technology to map the different episodes of this vegetation recovery process. A time series of Landsat imagery acquired from 1977 through 2017 at 10-year intervals was used to map and analyze the changes in vegetation cover in CB. These maps were used to generate a single thematic map indicating in which 10-year period each parcel of land was revegetated. Analysis shows that the extent of non-vegetated areas continuously decreased from about 38.5 to 2.5 km2 between 1977 and 2017. The greatest increase in vegetation regrowth occurred between 1987 and 1997, which was the period when all mining and smelting activities ceased. This research could be very useful to better understand the recovery process of areas affected by mining and smelting processes.