JP2013256753A - High pressure injection method and soil improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high pressure injection method with which a ground can be efficiently cut to enlarge a cutting range and mud can be softened uniformly by mixing cut mud and water uniformly, and a soil improvement method employing the high pressure injection method.SOLUTION: When cutting a ground by injecting high pressure water J into the ground G, according to a high pressure injection method, the high pressure water is injected at a temperature higher than a mud temperature within the ground by 20°C or more and lower than a water boiling temperature.

Description

  The present invention relates to a high-pressure injection method for injecting high-pressure water in the ground and a ground improvement method using this high-pressure injection method.

  In the high-pressure jet stirring method such as the column jet grout method, the ground is improved by cutting the ground with high-pressure water and then injecting a solidified material to create an improved body in the ground.

  For example, in Patent Document 1, high pressure water is injected from a high pressure liquid injection nozzle provided at the tip of an injection pipe inserted into the ground to loosen the target ground to form mud, and then solidified material slurry or the like in the loose ground A ground improvement method is disclosed in which a self-hardening material to which is added is pressed into the mud to remove the loose mud and is replaced with the self-hardening material to create a ground improvement body.

  Patent Document 2 proposes a soil stabilization method in a cold region that uses high-temperature cement slurry so that the stabilized soil does not freeze. Patent Document 3 proposes a soft geological improvement method using bored in the depth direction by high-pressure injection using hot water or using cement slurry divided into hot water.

Japanese Examined Patent Publication No. 7-111052 JP 2010-180691 A JP 58-168717 A

  According to the conventional construction method, there is a limit to the range of ground that can be cut by one high-pressure injection, and an efficient cutting method has been demanded. Moreover, the mixing of the clay and water in the cutting range after cutting may not be uniform, and the improvement of the quality of the improved body produced after that was one of the problems.

  In view of the above-described problems of the conventional technology, the present invention can efficiently cut the ground to increase the cutting range, and can uniformly cut soft mud by uniformly mixing the cutting mud and water and the high pressure. It aims at providing the ground improvement construction method using the injection method.

  In order to achieve the above object, the high-pressure injection method according to the present embodiment is a high-pressure injection method in which high-pressure water is injected into the ground to cut the ground, and the high-pressure water is discharged from the mud temperature in the ground. It is characterized by spraying at a temperature of ℃ or higher and lower than the water boiling temperature.

  According to this high-pressure injection method, by using high-temperature high-pressure water that is 20 ° C. or more higher than the mud temperature in the ground, the jet flow attenuation is reduced and the jet reachability is improved, so the ground is efficiently cut. The cutting range can be increased. Moreover, the temperature of the high-temperature water is lower than the water boiling temperature and is not high enough to boil, so that temperature management is easy. Moreover, since the cutting mud and water are easily mixed uniformly, the mud can be uniformly softened without leaving an unmixed soil mass. As a result, the work efficiency and the quality of the improved body created in the ground can be improved.

  Preferably, a temperature sensor is disposed in the vicinity of the injection nozzle that injects the high-pressure water, and the temperature of the high-pressure water is controlled to be a predetermined temperature based on the measurement result of the temperature sensor. Thereby, the temperature of high temperature water can be reliably controlled and managed.

  An injection apparatus comprising: a rod through which the high-pressure water passes; and first, second, and third injection nozzles that are sequentially arranged in the longitudinal direction of the rod and that inject the high-pressure water in a horizontal direction. It is preferable to perform the said injection using.

  When the three-point injection type injection nozzle is used, the nozzle diameter of the second injection nozzle arranged at the center is smaller than the diameters of the first and third injection nozzles arranged at both ends thereof. Is preferred. Thereby, the reachability of a jet can be improved further.

  The ground improvement method according to the present embodiment uses the above-described high-pressure spraying method to perform ground cutting by injecting the high-pressure water in the ground to be improved, thereby forming a soft mud zone, and an improved body in the soft mud zone. It is characterized by creating.

  According to this ground improvement method, by using high-temperature high-pressure water that is 20 ° C or more higher than the mud temperature in the ground, the jet attenuation is reduced and the jet reachability is improved, so the ground can be cut efficiently. The cutting range can be increased. Moreover, since the temperature of high-temperature water is less than the water boiling temperature and is not high enough to boil, temperature management is easy. Moreover, since the cutting mud and water are easily mixed uniformly, the mud can be uniformly softened without leaving an unmixed soil mass. As a result, it is possible to improve the work efficiency and the quality of the improved body created in the improvement target ground.

  In this specification, the mud temperature in the ground means the temperature of the soil (consisting of soil particles, pore water, and air) constituting the ground to be cut.

  According to the present invention, there is provided a high-pressure injection method capable of efficiently cutting the ground and increasing the cutting range, and uniformly mixing the cutting mud and water and uniformly softening mud, and a ground improvement method using this high-pressure injection method. Can be provided.

It is the schematic for demonstrating the main process (a) (b) (c) of the ground improvement construction method using the high-pressure-injection method by 1st Embodiment. It is a block diagram which shows the high pressure injection system for performing the high pressure injection method in FIG. It is principal part sectional drawing which shows the temperature sensor position attached to the injection nozzle vicinity of the rod which performs the high pressure injection of FIG. It is the front view (a) and side view (b) which show the rod and injection nozzle by the modification of this embodiment. It is the schematic for demonstrating the main processes of the ground improvement construction method using the high pressure injection method by 2nd Embodiment. It is the schematic of the experimental water tank which performed Experimental example 1. FIG. It is a graph which shows the relationship between the distance from the jet nozzle in Experimental example 1, and the measured flow velocity. It is a graph which shows the relationship between the water temperature in Experimental example 2, and the measured vane shear strength.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram for explaining main steps (a), (b), and (c) of a ground improvement method using the high-pressure injection method according to the first embodiment. FIG. 2 is a block diagram showing a high-pressure injection system for executing the high-pressure injection method in FIG. FIG. 3 is a cross-sectional view of the main part showing the position of the temperature sensor attached to the vicinity of the injection nozzle of the rod that performs high-pressure injection in FIG.

  The ground improvement method of the present embodiment is to create an improved body by cutting the ground to be improved using high-temperature and high-pressure water and filling the ground with a filler. A high-pressure injection system 20 for this purpose will be described with reference to FIGS.

  As shown in FIG. 2, the high-pressure injection system 20 includes a high-pressure pump 21 that sends high-pressure water to the injection nozzle, a tank 22 that can supply high-temperature water to the high-pressure pump 21, and a water supply pipe that supplies water to the tank 22 from the outside. 23, a heater unit 24 installed in the tank 22 for heating the water in the tank 22 to a predetermined temperature, a power supply unit 25 for energizing the heater unit 24, a temperature sensor 27 for measuring the temperature in the vicinity of the injection nozzle, and a temperature sensor And a control unit 26 that maintains the water temperature in the tank 22 at a set temperature by controlling the energization amount to the heater unit 24 of the power supply unit 25 based on the measurement result of 27.

  As shown in FIG. 3, an injection nozzle 13a is provided on a high pressure water injection rod 12 made of a pipe. The temperature sensor 27 is attached to the inner surface of the rod 12 in the vicinity of the upper portion of the injection nozzle 13a. A lead wire 28 from the temperature sensor 27 extends from the inner surface of the rod 12 to the outside and is connected to the control unit 26 in FIG. As the temperature sensor 27, for example, a thermocouple type temperature sensor can be used. The mounting position of the temperature sensor 27 may be the outer surface of the rod 12.

  The ground improvement method according to the present embodiment will be described with reference to FIGS.

  First, a hole is drilled from the ground surface S using a boring tool, and a hole A ′ is formed in the ground G as shown in FIG.

  Next, as shown in FIG. 1A, the tool 10 is inserted into the hole A 'from the ground surface S in a state of being attached to the backhoe BH.

  The tool 10 has a rod 12, and the rod 12 has an injection nozzle 13a provided for injecting high-pressure water on the side of the monitor 13 on the tip side, and a tip for feeding the filler into the ground and filling it. And a filling port 13b provided on the side, and has a double tube structure.

  Next, the high-pressure injection system 20 of FIG. 2 is operated, and high-temperature water from the tank 22 is sent to the rod 12 by the high-pressure pump 21, and the high-temperature high-pressure water J is supplied from the injection nozzle 13 a of the monitor 13 as shown in FIG. Is sprayed horizontally. At this time, the temperature of the high-pressure water is set to be lower than the water boiling temperature by 20 ° C. or more than the mud temperature in the ground, and the control unit 26 in FIG. Control the energization amount.

  As shown in FIG. 1B, the ground G is cut with a predetermined radius by rotating the tool 10 in the rotation direction d while injecting the high-temperature and high-pressure water J. Then, the filler is sent out from the filling port 13b at the tip of the monitor 13 while the tool 10 is pulled upward c. In this way, the ground G is cut at a predetermined radius and a lifting height to form a relaxation space by rotating the tool 10 and ejecting the high-temperature and high-pressure water J from the ejection nozzle 13a while pulling up at a constant speed. While the inside is mud, the filler is filled into the relaxation space from below by sending out the filler from the filling port 13b and press-fitting it. When the filler is press-fitted, as shown in FIG. 1B, the filling port 13b at the tip of the monitor 13 is preferably in the filled filler. The filler may be a slurry obtained by adding a solidifying material such as cement to, for example, mud extruded from the relaxation space.

  In the middle of the above-described cutting and filling process, as shown in FIG. 1B, the filler is filled by press-fitting from the lower portion B1 of the improvement target portion in the ground G and is sequentially filled into the upper portion B2. . At this time, the mud in the upper part B2 is pushed up to the upper b as the lower part B1 is filled with the filler, and finally pushed out to the ground surface S and removed.

  As shown in FIG. 1C, when the tools 10 are pulled up by a predetermined length and filled with a filler in the relaxation space, the filling is completed and the tools 10 are pulled up. Thereby, the improved body B can be created in the ground G. Thus, the improved ground can be created by press-fitting the filler into the ground.

  As described above, in this ground improvement method, high-temperature and high-pressure water is sprayed from the spray nozzle 13 a in the monitor 13 of the tool 10 to cut the ground to make mud, and the filler is filled from the filling port 13 b at the tip of the monitor 13. The filling mud is filled from the lower end of the cutting mud and the cutting mud on the filling material is discharged to the outside, so the cutting mud can be replaced with the filling material without mixing the cutting mud and the filling material. it can.

  In addition, by jetting high-pressure water of 20 ° C. or higher than the mud temperature in the ground to cut the ground, the effect of reducing the attenuation of the jet flow from the jet nozzle 13a is reduced, the cutting range is increased, and the cutting diameter is increased. Have For this reason, the diameter of the improved body B becomes large, and the large improved body B can be created in the ground G.

  Also, because the high temperature water mixes well with the cut clay, etc., the mud is easy to soften, and when mixed with the solidified material to return the cut mud discharged outside as a filler, the solidified material and the cut mud Can be uniformly mixed, and a uniform filler can be obtained. Further, since the cutting mud with high-temperature water has a low specific gravity and is easily separated from the filler, it is possible to produce a high-quality improved body.

  As described above, when the temperature of the high-pressure water jetted from the jet nozzle 13a increases, the reason why the attenuation of the jet is reduced is that water generally becomes less viscous as the temperature increases. As a result of the reduced frictional resistance in the pipe, the injection flow rate increases, and the attenuation of the flow velocity of the jet flow becomes smaller than usual, so that the reachability of the jet flow is improved.

  Moreover, as a reason why cutting mud is easily softened by high-temperature water, a phenomenon that water generally increases in volume and viscosity decreases as the temperature increases. For this reason, when high-temperature water is used for ground cutting, the temperature of pore water that fills the gap in the soil skeleton structure rises. Due to the effect of decreasing the viscosity, the adsorbing power of clay particles and water particles decreases. As a result of improving the ease of mixing clay and water, the unmixed soil mass is reduced, and the clay in the cutting zone is uniformly softened.

  As described above, the diameter of the improved body can be increased and the homogeneous improved body can be created by cutting and softening the ground by high-pressure jetting of mud temperature in the ground + 20 ° C or higher in the horizontal direction. be able to. The high-temperature water used for ground cutting is not boiling water in which the ground splits due to thermal steam, so that temperature management is easy and the high-temperature water device does not increase in size.

  Next, as a modification of the present embodiment, a configuration example in which the injection nozzle provided on the rod is a three-point injection type will be described with reference to FIG. FIG. 4: is the front view (a) and side view (b) which show the rod and injection nozzle of a modification.

  As shown in FIGS. 4A and 4B, the injection nozzles 1, 2 and 3 are arranged side by side in the longitudinal direction of the rod 9. A high pressure pump 21 (FIG. 2) is connected to one end of the rod 9. The shape of the injection nozzles 1, 2, 3 when viewed from the front as shown in FIG.

  When the rod 9 is set in the vertical direction, the injection nozzles 1, 2 and 3 are arranged in the vertical direction, and the high pressure liquid is jetted from the injection nozzles 1 to 3 as jets J1, J2 and J3 by the high pressure pump. To do. The injection nozzles 1, 2, 3 are formed independently of each other on the outer surface of the rod 9. For this reason, the jets J1, J2, J3 jetted from the jet nozzles 1, 2, 3 are independent.

  The injection nozzles 1, 2 and 3 are arranged in a line in the longitudinal direction of the rod 9, and the diameter of the injection nozzle 2 arranged at the center is smaller than the diameter of the injection nozzles 1 and 3 arranged at both upper and lower ends thereof. ing.

Moreover, equal the diameter of the injection nozzle 1 and the diameter of the injection nozzle 3, the nozzle of the each cross-sectional flow area A ₀ of the injection nozzle 1 and 3, the cross-sectional flow area A _i of the injection nozzle 2 arranged in the center The water flow cross-sectional area ratio (A ₀ / A _i ) is preferably about 1.4 to 2.

  4A, the interval L between the center position of the injection nozzle 1 and the center position of the injection nozzle 2 and the interval L between the center position of the injection nozzle 2 and the center position of the injection nozzle 3 are A maximum of 15 mm is preferred.

  4 (a) and 4 (b), when high-pressure water is supplied from the high-pressure pump to the rod 9 set in the vertical direction, as shown in FIG. 4 (b), the injection nozzles 1, 2, 3, jets J1, J2, J3 are ejected in the horizontal direction. Compared to the one-point injection type, three injection nozzles are arranged in the vertical direction, of which only the central injection nozzle 2 is the injection nozzle 1 at both ends. , 3, the presence of the jets J1, J3 by the jet nozzles 1, 3 at both ends exerts the effect of suppressing the shaking and meandering of the main stream jet J2, and as a result, the jets J1- The arrival efficiency of J3 improves and increases. Accordingly, the diameter of the improved body B in FIG. 1 (c) becomes larger, and a larger improved body B can be created in the ground G.

  In addition, in a three-point injection type in which only the central injection nozzle 2 is smaller in diameter than the injection nozzles 1 and 3 at both ends, the distance L between the injection nozzles 1, 2 and 2 and 3 is 15 mm or less. The efficiency is high, and the jet liquid can reach farther.

Second Embodiment
FIG. 5 is a schematic view for explaining main steps of the ground improvement method using the high-pressure injection method according to the second embodiment.

  The ground improvement method of this embodiment is basically based on the column jet grout method. The ground to be improved is cut using high-temperature, high-pressure water and compressed air, and a solidified material slurry is injected into the ground to create an improved body. To do.

  As shown in FIG. 5, in the same manner as in FIG. 1A, drilling is performed from the ground surface S using a boring tool to form a hole A ′ in the ground G, and then the triple tube 30 is formed in the hole A ′. It penetrates inside.

  The triple pipe 30 has a triple structure so that the solidified material slurry, the high pressure water, and the compressed air pass through. The solid monitor slurry nozzle 31a, the high pressure water injection nozzle 31b, And a jet nozzle 31c for compressed air. The ground can be cut by injecting high-temperature high-pressure water in the horizontal direction from the injection nozzle 31b at the tip of the triple tube 30 and injecting compressed air in the horizontal direction from the injection nozzle 31c. High-temperature high-pressure water can be supplied to the triple pipe 30 using the high-pressure injection system 20 of FIG.

  As shown in FIG. 5, the ground tube G is moved to a predetermined direction by rotating the triple pipe 30 in the rotation direction d while jetting high-pressure water and compressed air having a temperature 20 ° C. higher than the mud temperature in the ground and pulling it upward c. The cutting space F is formed by cutting with a radius and discharging slime through the hole A ′ by a vacuum pump (not shown) from the discharge pipe 32 provided between the upper part of the hole A ′ and the ground surface S. Into this cutting space F, a slurry (solidifying material slurry) to which a solidifying material such as cement is added is injected from the nozzle 31a of the monitor 31.

  As described above, the triple pipe 30 is pulled up to a predetermined height, the cutting space F is filled with the solidified material slurry, and an improved body is created in the ground G. Since the attenuation of the jet flow from the injection nozzle 31b is reduced, the cutting range is increased, and the diameter of the cutting space F is increased, the diameter of the improved body B is increased, and a large improved body can be created in the ground G. .

  Moreover, since high temperature water and the cut clay etc. are mixed well and it is easy to soften, when discharging | emitting as slime, it becomes easy to discharge | emit from the discharge pipe 32, and while it can aim at the work efficiency, Even if a part of the material remains in the cutting space F, it is well mixed with the solidified slurry, so that the quality of the improved body can be improved.

(Experimental example)
Next, the present invention will be specifically described with reference to experimental examples. Experimental Example 1 is a high-pressure jet experiment, in which high-pressure water having different water temperatures is injected horizontally into the experimental water tank (water temperature: 12 ° C.) shown in FIG. 6, and the jet flow velocity after injection is electromagnetic at a predetermined position in the horizontal axis direction. Measured with a current meter (ACM-200, manufactured by Alec Electronics). A grout pump (maximum output: 3.5 MPa) was used for high-pressure water injection. There are two cases of high-temperature water: normal temperature (12 ° C, equivalent to water temperature in aquarium) and high temperature (50 ° C). The high temperature case is (mud temperature + 30 ° C) when the mud temperature in the ground is 20 ° C.

  FIG. 7 shows the relationship between the distance from the injection port and the measured flow velocity in Experimental Example 1. From the results shown in FIG. 7, the jet flow velocity in the high temperature (50 ° C) case is larger than that in the normal temperature (12 ° C) case, regardless of the distance from the injection port, and the distance attenuation is small. It turns out that the nature is high.

  The degree of mixing of water and clay according to the water temperature was confirmed by Experimental Example 2. In Experimental Example 2, in order to add water with a water content of 126% (mud temperature 20 ° C) and adjust the water content to 200%, the vane shear strength of the clay after adding water at each water temperature and stirring for 1 minute at 250 rpm Was measured. The water temperature was 5, 21, 30, 43, and 58 ° C in 5 cases. The vane shear strength was determined based on the “In-situ Vane Shear Test Method” of the Japan Geotechnical Society Standard (JGS 1411-2003).

  FIG. 8 shows the relationship between the water temperature and the measured vane shear strength in Experimental Example 2. From FIG. 8, as a result of uniform mixing as the temperature increased, a decrease in ground strength was confirmed. That is, the shear strength of clay (after water addition and stirring) decreased by about 15% at (mud temperature + about 20 ° C) and about 25% at (mud temperature + about 40 ° C), whereas (mud temperature + 10 ° C) ) Showed almost no change in shear strength. Since a decrease in shear strength was observed at (mud temperature + 20 ° C or higher), it was found that + 20 ° C or higher was appropriate for the temperature difference from the mud temperature in the ground.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the high-pressure injection method of the present invention is applied to the ground improvement method as shown in FIGS. 1 and 5, but the present invention is not limited to this, and can be applied to other methods of cutting the ground with high-pressure water. Of course there is.

12 Rod 13a Injection nozzle 13b Filling port 20 High pressure injection system 21 High pressure pump 27 Temperature sensor 1, 2, 3 Injection nozzle 9 Rod 30 Triple pipe 31b Injection nozzle B Improved body F Cutting space G Ground

Claims (5)

A high-pressure injection method in which high-pressure water is injected into the ground to cut the ground,
A high-pressure injection method characterized by injecting the high-pressure water at a temperature of 20 ° C. or more below the mud temperature in the ground and below the water boiling temperature.   The temperature sensor is arrange | positioned in the vicinity of the injection nozzle which injects the said high pressure water, The temperature of the said high pressure water is managed so that it may become predetermined temperature based on the measurement result of the said temperature sensor. High pressure injection method.   Using an injection device having a rod through which the high-pressure water passes and first, second, and third injection nozzles that are arranged in the longitudinal direction of the rod and inject the high-pressure water in the horizontal direction. The high-pressure injection method according to claim 1 or 2, wherein the injection is performed.   4. The high-pressure injection according to claim 3, wherein a nozzle diameter of the second injection nozzle arranged at the center is smaller than a diameter of the first and third injection nozzles arranged at both ends thereof. Method.   Using the high-pressure spraying method according to any one of claims 1 to 4, performing ground cutting by spraying the high-pressure water in the ground to be improved, forming a soft mud area, A ground improvement method characterized by creating an improved body.