Method for blending earth materials

Abstract: The invention relates to a method and apparatus for blending a mixture material directly into earth materials present in the soil. Cutter drums (4) rotatable at the end of a sinking shank (5) are used to effect blending of a mixture material (2) into an earth material (1) and, concurrently with the blending, to effect displacement of the blending materials by repeatedly moving the rotating drums (4) in the same direction while it is buried in the earth material.

Description: The present invention relates to a method for blending earth or soil materials, especially for blending a mixture material directly with earth materials present in the ground. A method of the invention can be applied e.g. in the following instances: 1. Load-bearing slabs or road-beds are constructed by blending on-site soil layers with suitable mixture materials, such as cement as a binder, power plant ashes for an improved density, and chemicals which, upon reacting, promote the setting and stabilization of the mixture compound. 2. The microbiological decontamination of earth can be initiated or it can be intensified by introducing microbes into the earth or soil or by modifying conditions to become favourable for decomposition activity. Hence, the question is about blending or mixing various microbes or chemicals within soil materials present in the ground. 3. The stabilization of earth materials is carried out by using suitable additives for solidifying or setting the earth materials, whereby contamination particles can be set in a less mobile condition for thus reducing the diffusion of contamination, such as toxins or oil. 4. In bentonite insulation, the bentonite used as an insulating material can be blended within on-site earth materials. The above list of examples is not exhaustive in terms of possible practical applications for a method of the invention. Thus far, there has been no available method capable of blending the mixture materials in a sufficient efficiency and to a sufficient depth directly within on-site earth or soil materials. However, the above-listed practical applications manifest that there is a major demand for such a method. In civil engineering, it can be used to replace piling and mixing at concrete stations. In stabilization or microbiological decontamination, it can be used for eliminating the need for lifting and replacing masses of soil. JP 59 122619 A shows ground improvement work without moving the excavated soil from the ground portion to the other places. The improving agent and soil and sand are stirred and mixed by large numbers of stirring blades turned by a motor in a bucket which is immersed into the ground. DE 30 23 002 A shows an apparatus for stabilization of earth materials directly on the ground. A rotatable blending shaft has projecting tools, which penetrate the ground. The blending depth and efficiency are limited. US 5 379 534 shows a soil improvement method using an excavation machine having its bucket equipped with a mixing device disposed therein. The mixing device can be rotated while the earth materials blended in the bucket fall through an opening formed through the bottom surface of the bucket. The object of the present invention is to obtain a method for blending earth materials effectively in deep and uniform layers. The characterizing features for a method of the invention are set forth in the annexed claim 1. The non-independent claims disclose preferred embodiments of the invention. The invention will now be described in more detail with reference made to the accompanying drawings, in which fig. 1 illustrates a blending process with a method of the invention and figs. 2 and 3 depict in more detail an apparatus for carrying out the blending in a front and side view, respectively. The way of implementing the method is described first in reference to fig. 1. A mixture material layer 2 is laid on the ground directly on top of an earth material 1 to be blended. A blending apparatus, designated generally with reference numeral 3, is mounted on the end of the boom of an excavating machine 11. In the illustrated case, the boom comprises arm elements 7 and 9, which are attached to each other by means of a hinge joint 14. The blending apparatus 3 connects to the arm element 7 by way of a hinge joint 13. A cylinder 8 can be used for maneuvering the blending apparatus 3 around the hinge joint 13 relative to the arm element 7 and a cylinder 10 can be used for maneuvering the arm element 7 around the hinge joint 14 relative to the arm element 9. The basic components of the blending apparatus 3 are a sinking shank 5 and a cutter drum 4 mounted on the end thereof, which can be driven around a horizontal axis in the rotating direction in which the top portion of the cutter drum 4 travels in the advancing direction of the working machine 11. The working machine 11 advances on top of a blended earth or soil material 12 towards the mixing or blending site. The actual blending is carried out in such a way that, while rotating, the cutter drum 4 is sunk in the layers 1 and 2 to be blended and is displaced from an initial condition shown in dash lines along a curving path indicated by an arrow A across the blending site towards the working machine 11, i.e. in a reverse direction relative to the advancing direction of the working machine 11. This displacement of the rotating cutter drum 4 while buried in earth materials to be blended carries the blending earth or soil material in front of it towards the blended layer 12, while some of the blending earth material returns along an overhead path above the cutter drum 4 back to the blending site. The earth material moving in front of the drum 4 will also be effectively blended or mixed. When the blending apparatus 3 is repeatedly worked thise way in the direction of the arrow A, the layers 1 and 2 to be blended can be displaced across the blending site to form the blended layer 12. The cutter drum 4 has a rotating speed within the range of 50-150 rpm. At lower speed, the mixing efficiency would remain insignificant and at higher speed the centrifugal force would sling material to be blended unnecessarily far or would return too much material over the drum 4 backwards and the progress of work would decelerate. The sinking shank 5 must have a sufficient length in order to bury the drum 4 to a sufficient depth. The shank 5 must have a length which exceeds the diameter of the drum 4 in order to establish a sufficient burying depth and a possibility of blending by slinging some of the mass over the drum 4 back to the blending site. A structural design of the blending apparatus 3 is depicted in figs. 2 and 3. Two cutter drums 4 are journalled around the opposite ends of a common carrier roll 9. Between the drums 4, the roll body 19 is fitted with the sinking shank 5, the other end of which is provided with fastening elements 6 for securing the same to the boom of a working machine. In the illustrated case, the fastening elements 6 include flanges 6a and 6b, which define therebetween a housing for a hydraulic motor 17. The flange 6b is fitted with an apertured engagement bracket 6c and an engagement bracket provided with a clamping slot 6d. Inside the sinking shank 5 extends a transmission shaft 18 parallel thereto, which is driven by the hydraulic motor 17. On the other hand, the shaft 18, through the intermediary of bevel gears (not shown) placed inside the carrier roll, rotates the cutter drums 4, both of which rotate in the same direction. The sinking shank 5 has a length which is chosen according to a desired application. In practice, the bottom surface of the cutter drums 4 has a maximum sinking depth within the range of 1,5-2 m. In practice, the required blending depths are within the range of 0,5-2 m. The shank 5 is provided with pipe 15 (fig. 3) for delivering to the blending site a variety of mixture materials, such as chemicals or microbial solutions. The hydraulic motor 17 can also be placed inside the roll body 19, the hydraulic hoses extending within the sinking shank 5. The hydraulic hoses are provided with couplings 16 which must be included in the top end of the shank 5, since the subsurface part of the apparatus cannot be provided with fragile components. The outer surface of the cutter drums 4 is provided with blades 20, which are cog-like or conical projections and extend in a direction which constitutes an acute angle relative to the radial direction of the cutter drum 4. The outer ends of the cutter drums 4 are provided with elements 21 in the shape of a truncated cone, which terminate in an auger-like drill bit 22. Thus, the cutter drums 4 do not become jammed between uncrushed flanking soil layers. In the present case, each cutter drum 4 has an axial length which is substantially equal to its diameter. However, the ratios between these dimensions may fluctuate to some degree according to a given application, depending on a required mixing depth and hardness of the ground. In order to facilitate the mixing actions of the apparatus, the shank 5 is flatter in the axial direction of the cutter drums 4 than in a direction perpendicular thereto for an easier passage of earth materials on either side of the shank 5. As shown in fig. 1, in a typical working position of the apparatus, the shank 5 is held in a substantially vertical position and manipulated on either side of a vertical line. Another essential feature of the invention is that the working direction A of the apparatus 3 during a mixing or blending action proceeds towards the working machine 11 and is reversed relative to the advancing direction of the working machine 11. The method of the invention can be implemented by using an apparatus, whose structural details differ in many ways from the above-described exemplary embodiment. All that is necessary for an apparatus implementing the method is that it includes one or more rotatable cutter drums mounted on the end of a sufficiently long sinking shank 5.

Claims: A method for blending earth materials, in which method a cutter drum (4) mounted on the end of a sinking shank (5) fastened to a boom (7-10) of a working machine (11) is rotated while buried in earth material to thus effect blending of earth materials and/or blending of a mixture material (2) into an earth material (1), characterized in that the working machine (11) advances on top of a blended earth material (12) towards the blending site; manipulation of one or more arm elements (e.g. 7) included in the boom (7-10) is used for maneuvering the cutter drum (4) within the blending site, while sunk in the earth material (1) to be blended, repeatedly towards the working machine (11) while the cutter drum (4) is rotating; and the cutter drum (4) is rotated around a horizontal axis, the rotating direction being such that the top portion of the drum (4) travels in the same direction as the advancing direction of the working machine (11). A method as set forth in claim 1 for blending a mixture material directly into earth materials present in the soil, characterized in that the mixture material (2) is laid prior to a blending process on top of the earth material (1) to be blended and/or is sprayed on the blending site during a blending process. A method as set forth in claim 1 or 2, characterized in that , during a blending process, the rotating cutter drum (4) has a sinking depth within the range of 0,5-2 m and a rotating speed within the range of 50-150 rpm. A method as set forth in any of claims 1-3, characterized in that the shank (5), which is used for sinking the cutter drum (4) in the ground, is held in a substantially vertical position and maneuvered on either side of a vertical line during a blending process.

Inventors: JONNINEN MARKKU, JONNINEN, MARKKU
Applicants: IDEACHIP OY
Application year: 1998
Main classification: E01C21
IPC codes: E01C21, E02D3