Deep soil compaction method and device for carrying out same

Abstract

The invention relates to technology for the deep compaction of cohesionless and weakly-cohesive soil and can be used in various sectors of construction during the preparation of foundations and during underground construction work. A deep soil compaction method includes introducing rods into the soil and subjecting said rods to a vibratory effect in a horizontal plane. Once a given degree of compaction has been reached, the rods are removed from the soil. The vibratory effect is applied at a frequency close to or greater than the natural oscillation frequency of the particles of the soil undergoing compaction. The rods additionally undergo reciprocating motion in the horizontal plane, with a number of working elements moving in antiphase to other working elements. A device for deep soil compaction comprises rods, a means for transmitting vibration to said rods, and a compacting plate. The technical result consists in increasing the deep (bulk) density of cohesionless and weakly-cohesive soils to promote strength and deformation properties across the layers thereof, while reducing the time spent on compaction.

Description

[0001] METHOD OF DEEP SOIL COMPACTION AND DEVICE FOR ITS IMPLEMENTATION

[0002] AREA OF TECHNOLOGY

[0003] The invention relates to the field of construction, namely to the technology of deep compaction of non-cohesive and weakly cohesive soil, including multi-layer soils from layers of non-cohesive and weakly cohesive soil, and can find application in various branches of construction in the construction of foundations of buildings and structures, as well as in underground work.

[0004] PRIOR ART

[0005] The most important stage of the construction process (above ground, underground) is the stage of soil compaction, which consists of increasing its density in order to impart the required strength and deformation properties. If the soil density is insufficient during construction and after its completion, the soil may settle under the weight of the structures being erected, which will lead to additional costs for the maintenance of such structures or even to the destruction of such structures. Currently, almost all types of construction sites and construction projects use mechanical soil compaction methods. The following soil compaction methods are known from the state of the art:

[0006] - a method that involves acting on the upper surface of the layer being formed (static or vibration or periodic impact);

[0007] - a method that includes the introduction into the soil of various substances such as glue, water and / or chemical additives that affect the interaction between the particles of the layer (layers) being formed;

[0008] - a method using explosions in the ground;

[0009] - a method consisting of the forced introduction into the structure of a compacted soil layer of various devices that provide vibration and / or impact on particles of loose soil or material in the layer(s) being formed;

[0010] - combined methods, including the stages of the methods listed above.

[0011] The known methods are implemented using various devices, such as static, vibration and impact rollers or trailed devices. In particular, RU2382537, published 27.02.2010, describes an impact roller that includes a rotation axis and a geometric surface of a cylindrical roller. The plane of symmetry of the roller is located perpendicular to the axis of rotation of the roller. Elements acting on the surface being processed are discretely and regularly placed on the surface of the roller. The elements are formed by the ends of hollow pipes rigidly fixed at one end to a support pipe connected to the roller axis, radially directed and rigidly connected to each other, together with a device placed on the free end of each of the pipes. The device contains a working element acting on the surface being processed in the form of, for example, a spring-loaded wedge or rammer. The working element is mounted with the possibility of limited linear movement along the axis of the hollow pipe.On the opposite fixed end in the cavity of each pipe a shock-absorbing end pad, for example, made of rubber, is fixed. A hammer is placed inside each hollow pipe. The hollow pipe and the hammer placed in it are made with the possibility of temporary fixing of the hammer in the hollow pipe and release. Temporary fixing of the hammer in the hollow pipe is carried out in the area adjacent to the shock-absorbing end pad. Release of the hammer from fixing occurs in its upper position during rotational movement of the roller with the possibility of its free fall down inside the pipe and impact on the rear part of the working element.

[0012] However, the depth of the impact action of the roller's working parts is insignificant and soil compaction occurs only in its upper layers. Such surface action leads to non-optimal movement of particles due to their constraint with neighboring particles and, consequently, to unsatisfactory density of their placement relative to each other. In addition, the thickness of the layer to be compacted in this way using a roller is strongly limited by the strength of the soil particles: an increase in the force applied to the surface of the compacted layer, when attempting to compact to a greater depth, can lead to the destruction of the particles if the applied force exceeds the strength of the particles. The destruction of particles means their division into smaller parts and the formation of dust (even smaller fractions), which leads to a decrease in the stability of the working contacts between such particles when a surface load is applied and, accordingly, to a decrease in the resistance to deformations of such a compacted structure.All of the above taken together does not allow for the required degree and depth of soil compaction, which results in the low bearing capacity of the processed soil obtained in the described manner using a roller.

[0013] A method of volume compaction of a railway track ballast prism is known, in which the crushed stone is completely cut out and cleaned, then the bottom layer is poured, which is compacted by vertical static and dynamic action of wedge-shaped compactors in the areas between the sleepers, and then a new layer of crushed stone is poured, which is compacted with a chipping hammer and a dynamic stabilizer transmitting vibration to the rails and sleepers in assembly and to the crushed stone ballast (RU2400589, published 27.09.2010). The device for compacting the bottom layer is wedge-shaped compactors installed on a crushed stone cleaning machine, which perform continuous cyclic movement with continuous translational movement of the machine, and vertical movement with a depth of 150-200 mm from the foot of the sleepers.

[0014] However, the described method does not ensure obtaining a soil base with high bearing capacity, which is due to the following. The crushed stone layer is exposed to the action of wedge-shaped compactors in zones, locally (only in the areas between the sleepers). This leads to the fact that the particles change their position and orientation, compacting only in the projection of the wedge-shaped compactors, and the crushed stone in the zones located in the projection of the sleepers is unaffected, i.e. not compacted. During operation, under the train load, such a base, uneven in density, is subjected to vibration and pressure effects over the entire surface, including the zones under the sleepers. As a result, the particles under the sleepers change their position and orientation, compaction of these zones and subsidence of the layer under the sleepers occurs, which entails subsidence of the track. In addition, compaction in the zones between the sleepers occurs uncontrollably, i.e.the particles move (change their position and orientation) uncontrollably, and if the particle movements exceed the average particle size, this leads to a complete change in the position of the particles relative to their initial position, thereby preventing the formation of a layer (layers) resistant to deformations, which also negatively affects the operational characteristics of the soil base. In addition, the prototype method does not take into account the shape, size and other parameters of the particles included in the structural layer (the degree of contamination of the particles, their roundness, porosity at the micro level, strength, natural oscillation frequency, humidity), which does not allow achieving a high bearing capacity of the compacted layer throughout its thickness.

[0015] The closest in technical essence to the claimed method is the method of deep compaction of ballast railway track (RU2517407, published 20.01.2014). The method includes forced penetration of a tool into the ground, rotation of the tool in one direction and / or with a change in the direction of rotation, and subsequent extraction of the tool. In this case, additional vibration action is exerted on the compacted medium by means of the tool, and gas and / or liquid and / or gas-liquid mixture are supplied to the compacted soil. The tool used to implement the method is one or more rods, which can be made of various shapes, with protrusions, and can also be equipped with compaction plates, rigidly or movably installed above the working part of the tool and / or in the area of ​​the working part of the tool.In this case, the rods are located no less frequently than the maximum size of the particles of the compacted medium, which makes it possible to eliminate the leakage of particles of the medium between the rods.

[0016] The disadvantage of the known method chosen as a prototype is the impossibility of obtaining a soil base with high bearing capacity for several reasons. Accurate determination of soil fractions, in particular crushed stone, in the conditions of construction and maintenance of the base is very difficult. At the same time, even if the average maximum size of crushed stone in the compacted mass is identified and the rods are installed at a distance corresponding to this size, there is a high probability that crushed stone that exceeds the installation distance in size will get stuck between them. This in turn will lead to jamming of the mechanisms rotating the rods, failure of the device as a whole, as well as to the appearance of "unprocessed" soil areas and, accordingly, subsidence of the soil when an operational load is applied.If the crushed stone does not get stuck between the rods, then its sufficient compaction still cannot be achieved, since the rotating rods essentially only mix the particles in the total volume of the compacted layer, i.e. completely turn over and move the particles in space in a disorderly, chaotic manner, as a result of which the particles occupy a random unstable position, with a minimum number of stable working contacts. At the same time, the optionally applied vibrating effect cannot minimize the instability of such a position due to the mentioned minimum number of stable working contacts of the particles.

[0017] DISCLOSURE OF THE ESSENCE OF THE INVENTION

[0018] The objective is to develop a method and device for deep soil compaction to obtain soil foundations with high bearing capacity.

[0019] The technical result consists in increasing the depth (volume) density of loose and weakly bound soils in order to impart the required strength and deformation properties throughout the entire thickness of the layer (layers) while reducing the time spent on compaction.

[0020] The technical result is achieved in that in the method of deep compaction of soil, in which rods are introduced into the soil, a vibrating effect is given to them in a horizontal plane, the soil is compacted until a given degree of compaction is achieved, and then the rods are removed from the soil, according to the invention, the vibrating effect is given with a frequency close to or exceeding the frequency of natural oscillations of the particles of the soil being compacted, and the rods are additionally given a reciprocating motion in a horizontal plane, wherein one part of the elements of action moves in antiphase to the other part of the elements of action.

[0021] In a particular embodiment of the method, after removing the rods, the soil is additionally compacted; and / or compaction is performed with a frequency of 15-60 Hz and an amplitude of 5-100 mm.

[0022] The technical result is also achieved in that the device for deep compaction of soil, including rods, a means for imparting vibration to the rods and a tamping plate, according to the invention, contains two bases, on each of which half of the rods are installed in at least one row, wherein the bases are designed with the possibility of reciprocating movement relative to each other in a horizontal plane.

[0023] In a particular embodiment of the device, the bases contain a plurality of shelves and are arranged in such a way that the shelves of one base are located in the gap between the projections of the shelves of another base; and / or the bases are made U-shaped or U-shaped; and / or the tamping plate is made with openings and is installed movably in such a way that the rods pass through the openings.

[0024] The authors have experimentally established that the claimed modes of the method, as well as the design features of the applied device versions, are optimal for deep volumetric compaction of loose and weakly bound soils in a short period of time. This is due to the fact that the invention allows for the implementation of a combined mechanical deep effect on the soil in two or more directions. The first direction of action consists in creating the effect of compression and expansion on the volume of soil, extending over the entire depth of compaction at one time. This is achieved by forming a volumetric space in the form of triangular prisms limited by the trajectories of the rods moving in different directions. The second direction of action consists in non-directional vibration of the rods in one plane, and the third direction - in non-directional vibration of the rods in another plane (for example, in the horizontal and vertical planes, respectively).In this case, the frequency of such vibrations is of exceptional importance, which should be close to or exceed the natural frequency of oscillations of the compacted soil particles. The combination of multiple effects, implemented simultaneously, rather than sequentially, allows the particles to take an equilibrium position in the structure relative to neighboring particles, i.e. such a state that will be the most probable and stable for each particle, taking into account its geometric shape, size, weight and features of the surrounding conditions, which is essentially a controlled repacking of particles, i.e. the movement and change of orientation of particles relative to their initial position is limited. In this case, uncontrolled movements of particles (their mixing) are absent, since they are under external directed effects throughout the compaction process.The ramming action on the surface of the compacted layer following the above-mentioned actions allows for the elimination of voids left after the removed rods and for the "bringing" of the position of particles with a density greater than that already achieved, without destroying the soil particles, i.e. bringing them closer to each other in their most probable position in the layer massif with the maximum number of stable working contacts. Thus, in the shortest possible time, high soil density is achieved throughout the entire depth (throughout the entire volume), which determines the required strength and deformation properties and, consequently, high bearing capacity.

[0025] BRIEF DESCRIPTION OF DRAWINGS

[0026] The claimed invention is illustrated by drawings, where Fig. 1 shows a device for deep compaction of soil in general form, Fig. 2 is a view of the configuration and mutual arrangement of the bases and the tamping plate (without the supporting plate), Fig. 3 is a view of the configuration and mutual arrangement of the bases and the tamping plate (with the supporting plate), Fig. 4 is a bottom view of the tamping plate with rods passing through its openings, Fig. 5 is a model of an elementary volume of soil limited by the elements of action of the device for deep compaction, Fig. 6 is a top view of a layer of compacted soil, where the lines indicate the boundaries of the triangular prisms.

[0027] IMPLEMENTATION OF THE INVENTION

[0028] The device for deep compaction of soil is made in the form of a frame structure, in which the supporting plate 1 is connected to the tamping plate 2 by means of sliding bearings 3 through posts 4, which allows the tamping plate to be vertically movable (lowered for compaction and raised to the upper position). The tamping plate 2 is equipped with a vibrator 5, which can be installed, for example, on the supporting plate 1 and set a directed vibrating effect of a given frequency and amplitude through a vibrating bridge 6.

[0029] On the supporting plate 1, bases 7 and 8 with rods 9 are installed, made with the possibility of reciprocating movement relative to each other in a horizontal plane and installed relative to each other in such a way that the rows of rods 9 of each base 7 and 8 alternate. For this, bases 7 and 8 can be made in the form of flat elements of a complex geometric shape with a plurality of shelves (for example, U-shaped or W-shaped) and are located in such a way that the shelves of one base are in the gap between the projections of the shelves of the other base (Fig. 2).

[0030] The reciprocating movement of bases 7 and 8 is carried out using corresponding hydraulic cylinders 10, 11.

[0031] The rods 9 are installed in at least one row on each base 7 and 8. In this case, the rods of the base 7 are shifted relative to the rods of the base 8 in the horizontal plane in such a way that the points of their (the rods') attachment to the bases can be considered as a set of vertices of triangles, which are the bases of a set of prisms. A schematic representation of one such triangle is shown in Fig. 2. An approach based on dividing a large area (volume) into smaller parts is widely known and, in particular, is used in the finite element method for solving problems of engineering and mathematical models. In the claimed invention, such an approach makes it possible to predict the distribution of stresses from the rods to the particles inside the prism, to estimate the bearing capacity and other characteristics of the compacted medium placed inside one prism, based on the values ​​of normal and tangential stresses, as well as deformations occurring during the interaction of the prisms with each other.

[0032] The rods 9 are made with pointed ends, facilitating easy penetration into the compacted soil, and are made with a length corresponding to the specified compaction depth. Depending on the soil type, the rods can be made with a length from 10 cm to 1 m. The rods 9 can also be made of any shape, in particular, a triangular prism, a circular cross-section, a parallelogram, a parallelepiped, and / or be rotating and / or have channels for feeding any gaseous or liquid material into the volume of the compacted material in order to reduce the friction created between the particles of the compacted material, as well as between the vibrating elements themselves with the particles. The bases 7 and 8 are equipped with vibrators 12 and 13, transmitting non-directional high-frequency vibration of a specified frequency to the rods 9 to the corresponding bases. The vibration frequency can be from 15 to 60 Hz.

[0033] The tamping plate 2 is installed under the bases 7 and 8 and is made with openings 5 ​​14 through which the rods 9 pass.

[0034] The supporting plate 1 can be provided with lugs 15 or channels 16 to enable connection with a lifting and transport mechanism (for example, with a forklift).

[0035] The device for deep compaction of soil can be equipped with sensors 10 of any type for determining the degree of compaction at any stage and for determining the state of all working elements of the device, as well as a control unit and processing of data received from the said sensors, which facilitates effective control of the compaction process when monitoring the technical condition of the entire device.

[0036] The structural elements of the device (bearing plate, bases, tamping plate, rods) can be made of various materials that meet the required strength indicators.

[0037] The actuators (vibrators, hydraulic cylinders) can be equipped with power regulators to reduce the output power during compaction, if necessary. The actuators can be powered by any type of power plant, such as an internal combustion engine in combination with an electric generator and / or a hydraulic pump.

[0038] In addition, the device may be equipped with GPS and / or other sensors to determine its location, as well as a communication means for exchanging data with a remote data processing center about the location of the device and the compaction site, the degree of compaction achieved, and other status information in online mode.

[0039] The method of deep compaction of soil is carried out as follows. At the place of compaction of the soil on its surface, a device for compaction is placed, which can be installed on any transport vehicle (for example, on an excavator) or made in the form of a self-propelled vehicle on a wheeled chassis. 50 hydraulic cylinders 10, 11 and vibrators 12, 13 are switched on, under the action of which, as well as under the weight of their own weight, the bases 7 and 8 are lowered lower, as a result of which the rods 9 pass through the openings 14 of the ramming plate 2 and are driven into the soil. The reciprocating movement of the bases 7 and 8 is carried out in antiphase with an amplitude of 2-30 mm. In this case, the trajectories of the rods form a multitude of units of volumetric space (vertically oriented columns of soil) in the form of triangular prisms, in which the volume of soil is subjected to compressive-expanding effects (Fig. 5, 6).This effect, combined with high-frequency vibration (from vibrators 12, 13), allows the particles to take an equilibrium position in the structure relative to neighboring particles, i.e. a state that will be the most probable and stable for each particle, taking into account its geometric shape, size, weight and characteristics of the surrounding conditions, which is essentially a controlled repacking of particles, i.e. the movement and change of orientation of particles relative to their initial position is limited.

[0040] Next, the compaction plate 2 is lowered, which has a vibrating effect set by the vibrator 5, a given frequency and amplitude, which, depending on the parameters of the soil compaction requirement achieved by the stage, can be 15-60 Hz and 5-100 mm, respectively. Optionally, it is possible to regulate the compaction stage by adding a weight or by pressing force, for example, using a forklift on which the device is installed. The added weight depends on the depth of the compacted layer. As a result of the action of the compaction plate, the remaining voids are eliminated, and the position of the particles with a density greater than that already achieved is brought, without destroying the soil particles, i.e. they are brought closer to each other in their most probable position in the layer array, after which the rods are removed. An option is possible when, after removing the rods, the soil is additionally compacted in order to eliminate the voids left after the removed rods.Thus, in the shortest possible time, high soil density is achieved throughout the entire depth (throughout the entire volume).

[0041] The duration of the phase of action by vibrating elements (rods) depends on the initial parameters of the soil (degree of looseness, size of fraction, humidity, etc.) and can be limited by such a degree of compaction when vibration of rods 9 becomes difficult or impossible. An indicator of this can be a slowdown (or stop) in the operation of hydraulic cylinders 10, 11 due to increased resistance of the compacted material.

[0042] Thus, the claimed invention ensures the production of soil foundations with high bearing capacity by increasing the depth (volume) density of loose and weakly bound soils in order to impart the required strength and deformation properties throughout the entire thickness of the layer (layers) while reducing the time spent on compaction (per one cycle of the working pass of the tool).

Claims

CLAUSE OF INVENTION 1. A method of deep compaction of soil, in which rods are inserted into the soil, they are given a vibrating effect in a horizontal plane, the soil is rammed until a given degree of compaction is achieved, and then the rods are removed from the soil, 5 characterized in that - the vibrating effect is given with a frequency close to or exceeding the frequency of natural oscillations of the particles of the compacted soil, - the rods are additionally given a reciprocating motion in the horizontal plane, with one part of the impact elements moving in L0 is in antiphase with the other part of the impact elements.

2. The method according to paragraph 1, characterized in that after removing the rods, the soil is additionally compacted.

3. The method according to item 1, characterized in that the ramming is performed with a frequency of 15-60 Hz and an amplitude of 5-100 mm. 15 4. A device for deep compaction of soil, including rods, a means for imparting vibration to the rods and a tamping plate, characterized in that it contains two bases, on each of which half of the rods are installed in at least one row, wherein the bases are designed with the possibility of reciprocating movement relative to each other in a horizontal plane. 'O 5. The device according to item 2, characterized in that the bases contain a plurality of shelves and are arranged in such a way that the shelves of one base are located in the space between the projections of the shelves of the other base.

6. The device according to item 2, characterized in that the bases are made U-shaped or W-shaped. '5 7. The device according to item 2, characterized in that the tamping plate is made with holes and is installed movably in such a way that the rods pass through the holes.

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