Patent Application
20110103898
1. Field of Invention
The present invention relates generally to methods for hydraulic infrastructures reinforcement and rehabilitation, and more particularly to a directional fracture grouting method with polymer for seepage control of dikes and dams.
2. Description of Related Arts
The safety of hydraulic infrastructures such as reservoirs is one of the top priority safety concerns. If a reservoir collapses, it could cause heavy damages to properties or even casualties. Seepage, a problem commonly associated with dams or dikes, is generally considered as a hidden danger. Many dam disasters were caused by the failure of their seepage control systems. Various solutions have been proposed. Among the available options, fracturing or splitting grouting is a commonly used method or technique.
The theory base for fracturing grouting is that the minimum principal stress plane is parallel or in the same direction as the axial direction of a dike or dam. Based on this theory and the principles of hydraulic fracturing, the technique of fracturing grouting comprises drilling holes along the axis of a dike or dam where the reinforcement mechanism is supposed to be installed. A grout composition is then injected into the holes. Under the hydraulic fracturing effect and the injecting pressure energy, the grout composition forces its way into hidden cracks, holes, fills up the voids and gets the soil compacted. As a result, it forms vertical, continuous, and impermeable barriers inside the dike or dam, thus achieving seepage control and dam reinforcement. Cement slurry is commonly used in the fracturing grouting technique, which has the following shortcomings:
It is clear that the existing fracturing grouting technique can't satisfactorily meet the requirements for seepage control of dikes and dams. Developing a better and more effective technique for seepage control for dikes and dams has become imperative.
Grouting with polymer, a technique developed since 1970s, allows rapid treatment for foundation repair. It has been used to reinforce foundations, fill up hollow spaces underground, or elevate floor by injecting two-component polymer materials into the foundation which then expands under chemical reaction and then coagulates. At present, grout polymer has been applied mostly in foundation repair or road maintenance. There is no report about techniques of directional fracture grouting with polymer for dikes and dams.
An object of the present invention is to provide a directional fracture grouting method with polymer for seepage control of dikes and dams to use non-water reacted two-component polymeric material to form super thin polymer segments. The segments overlap each other so as to construct a continuous super-thin polymer seepage control system inside a dike or dam.
Another object of the present invention is to provide a directional fracture grouting method with polymer for seepage control of dikes and dams to construct a polymer seepage control system which has improved impermeability and durability.
Another object of the present invention is to provide a directional fracture grouting method with polymer for seepage control of dikes and dams to construct a polymer seepage control system which is a fast reinforcement technique as the polymer composition achieves more than 90% of its full strength under chemical reaction in about 15 minutes after being injected.
Another object of the present invention is to provide a directional fracture grouting method with polymer for seepage control of dikes and dams to construct a polymer seepage control system of which its thickness and density of the curtain can be optimized in accordance to project-specific requirements, making rooms for cost saving.
Another object of the present invention is to provide a directional fracture grouting method with polymer for seepage control of dikes and dams to construct a polymer seepage control system which is able to produce polymer grout curtains just a few millimeters thick and has minimal disturbing impact to dikes and dams during construction.
Thereby, in order to accomplish the above objects, the present invention provides a directional fracture grouting method with polymer for seepage control of dikes and dams, comprising the steps of:
Thereby, under the chemical reaction of the two components of the polymer, the mixed material expands and becomes foamed solid from liquid, generating an expanding power inside the soil of the dike or dam. When the expanding force exceeds the tensile strength of soil, the soil is fractured along the intended splitting directions guided by the two wings of the special drilling tool, and the material forms a super thin polymer segment. The polymer segments are overlapped each other, and the seepage control system is constructed inside the dike or dam.
These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.
Referring to
Thereby, under the chemical reaction of the two components of the polymer, the mixed material expands and becomes foamed solid from liquid, generating an expanding power inside the soil of the dike or dam. When the expanding force exceeds the tensile strength of soil, the soil is fractured along original splitting directions guided by the two wings 22 of the special drilling tool 20, and the material forms a super thin polymer segment 50. Finally, the polymer segments are overlapped each other, and the seepage control system 60 is constructed inside the dike or dam. (61 shown in
As a side note—the field tests and theory modeling done by the inventor have shown that if the drilling holes were round, due to the non-homogeneous nature of soil, the expanding force generated by the injected polymer material under chemical reaction will fracture the soil from the relatively weak zones first, and then goes wherever the splitting or cracking goes. Because of the complexity of soil, the splitting or fracturing directions can not be determined or controlled.
In summary, the present invention provides a novel concept and technique for guiding the polymer grout to fracture the soil in a directional manner. Different from the conventional splitting grouting holes, the directional fracture grouting holes are not round. They are formed by using a special drilling tool 20 to split the soil at two sides of the round hole according to a predetermined angle. The effect is that once the polymer material is injected into the directional fracture grouting hole and expanded under the chemical reaction, the soil is fractured by the expanding force, along the intended splitting directions guided by the special drilling tool 20. Then as the polymer material further expands within the hole and the split soil, the soil will be further fractured generally along the intended splitting direction.
Because the directional fracture grouting holes are not round, they cannot be formed by the common drilling tools and methods. The present invention provides a direct pushing method and uses a hydraulic equipment such as a static cone penetration system to push a special drilling tool 20 into a predetermined depth of the soil, and thus to form the directional fracture grouting hole 10.
The special drilling tool 20 comprises a cylindrical drill bit 21 and two wings 22 welded at two sides thereof according to a predetermined angle, respectively. When the drilling tool 20 is pushed into the soil, the two wings 22 split simultaneously the soil to form each of the directional fracture grouting holes 10. Each of the two wings 22 is designed to have a triangle-like shape such as an equilateral triangle, a semicircle, or any other shapes of suitable to be pushed into soil, a height of which is 6-8 cm in general and is adjustable according to the characteristics of soil.
As mentioned above, the two wings 22 are welded at the cylindrical drill bit 21 according to a predetermined angle α23. In order to lap conveniently, the predetermined angle 23 is set to 160-170 degrees facing upstream and is adjustable.
Preferably, the predetermined distance between two adjacent directional fracture grouting holes 10 is about 1 m, and is adjustable. If the predetermined distance is too far, it is difficult for the super-thin polymer segments 50 to lap over each other. If the predetermined distance is too close, the efficiency of constructing the super-thin polymer seepage control system 60 is lowered.
In general, a length of the hole-sealing grouting pipe 30 is set to 1 m below the ground surface, and is adjustable. A length of the fracture grouting pipe 40 is determined according to actual situation of project.
Compared with the traditional methods for seepage control of dikes and dams, the directional fracture grouting method with polymer for seepage control of dikes and dams provided by the present invention has following characteristics of:
All in all, the present invention provides a directional fracture grouting method with polymer for seepage control of dikes and dams, and develops a novel method to combat seepage problems associated with dikes or dams. Some of the advantages include faster construction turnaround time, better impermeability, lower cost, and minimal disturbing impact to dams and dikes.
One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.
It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200910066334.8 | Nov 2009 | CN | national |
| 200910227699.4 | Dec 2009 | CN | national |
