JP2006118631A - Easily crushed land burial pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily crushed land burial pipe used for an investigation pipe for investigating the nature of the soil or ground water, a water service pipe, a water feed pipe, and a land burial pipe for injecting a liquid chemical to the ground, and capable of being easily crushed after achieving the using object. <P>SOLUTION: Cellulose fiber is contained in thermoplastic resin, the resin easily crushed is obtained, and the resin is formed as the material, or entire or partial thereof is formed of biodegradable plastics, the cellulose fiber is contained in it, and the resin easily crushed is obtained, and the resin is formed as the material. Even when the land burial pipe is left behind in the ground, the land burial pipe is crushed without being caught by a blade of an excavator in excavating work of a shield method, and decrease in working efficiency can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an easily pulverized underground pipe that is used in water or in the soil and is easily pulverized during excavation, and more particularly, a survey pipe, a distribution pipe, a water supply pipe, and a chemical solution for the ground. It is used for underground pipes for injection, etc., and is related to easily ground ground pipes that are easily pulverized after the purpose of use has been achieved.Furthermore, even if left in the ground and buried, The present invention relates to a buried underground pipe that can be easily crushed without being concerned about the workability being degraded by pulverizing even when entangled with a blade of an excavator during ground excavation work such as a shield method.

  When excavating tunnels in medium and hard rocks, explosive excavation with gunpowder has been the most common method, but recently mechanical excavation has become more common. Mechanical drilling does not loosen the ground and requires less excavation, noise vibration is much smaller than blasting, and there are fewer security deposits because no explosives are used. Recently, the construction examples have been steadily growing.

  In addition, recent trends in excavation methods have focused on working with face sections as large as possible. For this reason, as a supplementary construction method, there is often a face stabilization countermeasure that can be dealt with by mechanical equipment employed in normal construction, such as chemical injection, and that can be put within the cycle time of excavation work. Underground pipes will be installed in underground structures, underground structures, wells, etc. In addition, soil and water quality surveys on the planned excavation ground are also conducted in the survey wells.

As underground pipes such as the survey pipes, water distribution pipes, water supply pipes, underground pipes, etc., injection made by thermoplastic resin such as vinyl chloride, ABS resin, etc., by extrusion molding or injection molding. A tube is used. However, this type of injection tube has the property of a material that it is difficult to rot in the soil when buried in the ground and is easy to stretch without breaking when force is applied. For this reason, the resin of the material is entangled with the blade surface of the excavator, and the workability is lowered.
Japanese Patent No. 2514875 Japanese Patent No. 3406567

  The subject of the present invention is used in survey pipes for geological and groundwater surveys, water distribution pipes, water supply pipes, underground pipes for injecting chemicals into the ground, etc., which are easy to grind after use and buried in the ground. Even if it is left as it is, it is easy to crush the ground buried pipe that does not get entangled with the blade of the excavator during the ground excavation work, and is improved with the disadvantages of the above-mentioned known techniques. It is to provide.

  In order to solve the above-described problems, according to the underground pipe of the present invention, a thermoplastic resin containing cellulose fibers is used as a resin that can be easily pulverized, and this resin is used as a raw material, and an injection pipe that is easily pulverized. It is characterized by doing.

  Furthermore, in order to solve the above-mentioned problem, according to the underground pipe of the present invention, all or part of the pipe is made of biodegradable plastics, contains cellulose fiber and is easily pulverized, and this resin The injection tube is molded as a material and can be easily pulverized.

  The above-described buried pipe in the present invention is formed from a resin containing cellulose fibers in a thermoplastic resin, or all or a part thereof is made of biodegradable plastics and contains cellulose fibers therein. Because it is formed from resin, it is easy to be crushed or easily biodegraded in the soil, so it is easy to grind the underground pipe without tangling the excavator blade during excavation. The effect that it is done can be produced.

  As described above, the underground pipe according to the present invention contains cellulose fiber in a thermoplastic resin and is easily pulverized, and this resin is molded as a material pellet at a temperature of 300 ° C. or less by an extrusion molding machine or an injection molding machine. Processed and used for survey pipes for investigation of geology and groundwater, water distribution pipes, water supply pipes, underground pipes for injecting chemicals into the ground.

  Examples of the thermoplastic resin used in the present invention include polyethylene, polypropylene, polyacetal, polystyrene, nylon, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, polyethylene terephthalate, and polybutylene terephthalate. Then, one or more of these are used.

Examples of the cellulose fiber used in the present invention include fibers obtained by defusing plant fibers such as waste paper, wood flour, hemp, cotton pulp, and wood pulp. In the present invention, such cellulose fibers are kneaded into a thermoplastic resin at a moisture content of 5 to 40% and granulated. Alternatively, the cellulose fiber is kneaded with a thermoplastic resin in the presence of water whose moisture content of the cellulose fiber does not cut below the lower limit of 5%, and the obtained kneaded product is made in the range of 5 to 40% of the moisture content of the cellulose fiber. Grain.

  In the present invention, when cellulose fibers are used, it is important to fully consider the behavior of cellulose fibers during pellet production. Cellulose is a typical hydrophilic polymer substance that absorbs and desorbs moisture very much, and its properties change depending on the state of moisture absorption and desorption. That is, it swells and softens due to moisture absorption and becomes flexible and easily deformed, while it becomes keratinized and hardened by dehumidification, becomes brittle and difficult to deform.

  The reinforcing fiber used in the present invention is a vegetable fiber as described above, but after defibration or directly in a molten or softened thermoplastic resin at around 100 ° C. or higher, a strong shearing force is applied. Knead uniformly while applying. Under these conditions, the plant fiber mainly composed of cellulose loses moisture and becomes completely dry, so that it becomes keratinized and becomes brittle. Therefore, when kneaded by applying a strong shearing force in this absolutely dry state, the cellulose fiber is pulverized until it is uniformly dispersed in the thermoplastic resin, and the fiber shape is not retained.

  This tendency is more conspicuous in the case of a thermoplastic resin having a high melting temperature or softening temperature, and is not only affected by the deterioration of the fibers during the kneading but also by the further deterioration of the fibers and carbonization. Sometimes. In order to avoid this state, the underground pipe of the present invention is formed by injection molding or extrusion molding of a thermoplastic resin added with reinforcing fibers using a mold.

  Table 1 shows a comparison of properties between a conventional injection tube material and the injection tube material of the present invention, that is, a thermoplastic resin added with reinforcing fibers.

  As shown in Table 1, the material used in the present invention has a tensile strength equal to or higher than that of the material used in the conventional injection tube, but has a high elongation rate. In the excavation method using a conventional machine, when the elongation rate of the material of the injection pipe is high, if the blade hits the pre-filled injection pipe, it is not cut and deformed by external pressure. Therefore, it becomes entangled with the blade of the excavator, and it becomes difficult to dig the ground having a large surface of the blade, thereby reducing workability. Since the material used for the underground buried pipe of the present invention has a low elongation rate, it does not stretch even when an external pressure is applied, and it is easy to break. Thereby, the above-mentioned subject can be solved.

  The results of a destructive test of an injection tube made of a mixed material of vinyl chloride, paper and lactic acid polymer are shown below.

1. Sample a Injection tube made of vinyl chloride, inner diameter 40.2 x outer diameter 44.07 x height 101.67 (mm)
b Injection tube made of a mixture of paper and lactic acid polymer (biodegradable plastics tube)
Inner diameter 40.38 x outer diameter 45.33 x height 96.52 (mm)

2. Test method Cut the injection tube in half in the longitudinal direction and apply pressure from the lateral direction with a single screw compressor to break the tube. Observe the compression force and fracture shape at that time.

3. Experimental result
An injection tube made of vinyl chloride and an injection tube made of a mixture of paper and lactic acid polymer were cut in half from the longitudinal direction, and pressure was applied to the tube from the lateral direction by a uniaxial compressor. The photographs on the left side of FIGS. 1 and 2 show photographs of underground pipes before the uniaxial compression test. The photographs on the right side of FIGS. 1 and 2 show the state of destruction of the underground pipe after the uniaxial compression test. 1 and 2, the top is an injection tube made of vinyl chloride (sample A), the bottom is an injection tube made of a mixture of paper and lactic acid polymer of the present invention (sample B). Pressurized more.

Pressure was applied to the injection tube made of vinyl chloride and the injection tube made of a mixture of paper and lactic acid polymer from the lateral direction by a single screw compressor. The relationship between compressive strength (kgf / cm ² ) and strain distance (mm) is shown in the graph of FIG. As is apparent from FIG. 3, when a pressure of about 300 kgf / cm ² or more is applied to an injection tube made of vinyl chloride, the tube itself is deformed laterally from the point where the pressure is received, and the tube itself is destroyed. There was no. On the other hand, the injection tube made of a mixture of paper and lactic acid polymer according to the present invention was cracked at the point where the pressure was applied when a pressure of about 300 kgf / cm ² or more was applied. From this, it can be seen that the present invention obtains a high breaking strength in a region with a small strain. Therefore, it was proved that when excavating with sufficient strength as a buried pipe, it can be destroyed with a small strain, so that it becomes a buried pipe that can be easily crushed by excavation.

  Furthermore, the underground buried pipe of the present invention may be formed entirely or partially from biodegradable plastics, containing cellulose fibers therein to be easily pulverized resin, and this resin as a raw material.

  The above-mentioned biodegradable plastics used in the present invention is a polymer compound that is degraded by microorganisms, preferably thermoplastic, and can be processed by conventionally known extrusion molding, and has mechanical strength as an injection tube. Say things. Water-soluble plastics, particularly plastics that dissolve under alkaline conditions, are easily decomposed by living organisms and are preferred in the present invention.

  The chemical structure is (1) the main chain is aliphatic and has an ether bond or ester bond, (2) the main chain (or side chain) has a hydroxyl group or a carboxyl group, or (3) plastic. It is a plastic with good biodegradability by containing additives that induce and accelerate photodegradation and microbial degradation of starch, specifically starch-based, cellulose acetate-based, polylactic acid-based, aliphatic polyester-based, Examples thereof include biodegradable plastics such as polyvinyl alcohol. To these main raw materials, other polymer compounds such as plastics such as polyethylene and polypropylene, plasticizers, stabilizers, colorants and the like are added as necessary for the purpose of improving performance or imparting flexibility. You can also

  The compound (2) having a hydroxyl group or a carboxyl group is preferably an aliphatic compound. Specific examples of these biodegradable plastics include “Pionore” (aliphatic polyester of polyol and dicarboxylic acid) (Showa Polymer Co., Ltd. and Showa Denko Co., Ltd.), “Cell” Examples of “green” (cellulose acetate, polycaprolactone) (Daicel Chemical Industries, Ltd.), “lacty (lactic acid)” (Shimadzu Corporation), (2), “Poval” (polyvinyl alcohol) (Ltd.) Examples of (Kuraray) and (3) include “Wonder Starken” (corn starch and polyethylene) (Wonder Corporation) and the like.

  By blending the above biodegradable plastics with high melting point biodegradable plastics such as polyhydroxypropylate, polylactic acid, polyglycoside, etc., the processability is improved, and a woven fabric or non-woven fabric is used as a bag. Can also be used. These main raw materials are decomposed in the soil by bacteria for, for example, about 90 to 300 days.

  Biodegradable plastics is a surface reaction between the molded product and an enzyme that is metabolized from the body of the microorganism. Therefore, the thicker the molded product, the longer the degradation time. On the other hand, when the injection material is alkaline, biodegradable plastics having an ester bond are susceptible to hydrolysis. Moreover, the injection | pouring ground exists in various different conditions, such as acidic to alkaline or seawater penetration, and also changes with injection | pouring of injection | pouring materials. Therefore, the decomposition rate of the injection pipe cannot be generally determined, but when it is not excavated, it can be said that it is sufficiently short even for one year. Also, when drilling after injection, it is preferable to use more brittle biodegradable plastics.

  The biodegradable plastics according to the present invention can be decomposed or reduced in strength by reducing the weather resistance as required. When such an injection tube is used, particularly before the injection operation. For example, it is preferable to avoid exposure to direct sunlight for a long time or leaving it in the rain as much as possible.

  As the biodegradable plastics, tensile strength at break, tensile elongation at break, and degradation evaluation were measured for cellulose acetate type and polyester type, and the results are shown in Table 2.

  The underground buried pipe of the present invention is used in the underground or underground, such as a survey pipe, water distribution pipe, water supply pipe, underground chemical pipe for injecting chemical solution into the ground, and after reaching the purpose, It is easily destroyed by excavation work. For this reason, the fall of workability | operativity can be reduced in excavation works, such as a shield construction method, and its applicability is high in the technical field which uses the above-mentioned underground pipe.

It is a photograph of the underground pipe before uniaxial compression. It is a photograph of the underground pipe after uniaxial compression. It is the graph which showed the relationship between compressive strength (kgf / cm < ² >) and strain distance (mm).

Claims (8)

 A buried underground tube that is easily pulverized and made of a thermoplastic resin containing cellulose fiber to make it easily pulverized.   An easily pulverized underground pipe formed entirely or partially of biodegradable plastics, containing cellulose fibers therein to be easily pulverized, and made of this resin as a raw material.   3. The soil according to claim 1 or 2, wherein the underground pipe is a survey pipe, a water distribution pipe, a water supply pipe, or a underground pipe for injecting a chemical solution for investigation of geology and groundwater. Inside buried pipe.   The thermoplastic resin according to claim 1, wherein the thermoplastic resin is selected from the group consisting of polyethylene, polypropylene, polyacetal, polystyrene, nylon, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, polyethylene terephthalate, and polybutylene terephthalate. The underground pipe according to claim 1, which is a seed.   The underground tube according to claim 1 or 2, wherein the cellulose fiber is a fiber obtained by defibrating waste paper, wood flour, hemp, cotton pulp, or wood pulp plant fiber.   3. The underground pipe according to claim 2, wherein the biodegradable plastic is a thermoplastic polymer compound that is decomposed by microorganisms.   3. The underground pipe according to claim 2, wherein the biodegradable plastic is a plastic that dissolves under alkaline conditions. The underground pipe according to claim 2, wherein the biodegradable plastics is 1, 2 or 3 below.
(1) The main chain is aliphatic and has an ether bond or an ester bond.
(2) Those having a hydroxyl group or a carboxyl group in the main chain or side chain,
(3) Plastics with good biodegradability by containing additives that induce and promote photodegradation and microbial degradation of plastics, starch-based, cellulose acetate-based, polylactic acid-based, aliphatic polyester-based And biodegradable plastics selected from the group of polyvinyl alcohols.

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