JP5231319B2 - Strength estimation method of ground improvement body - Google Patents

Description

  The present invention relates to a method for estimating the strength of a ground improvement body, and more specifically, the mixture is stirred and mixed by injecting a hardening material liquid from an injection nozzle of an injection rod penetrating to a predetermined depth in the ground by a high-pressure injection stirring method. It is related with the strength estimation method of the ground improvement object created by this.

  A high-pressure jet agitation method is known as a method of improving the ground by consolidating the soft ground by injecting a hardening material liquid into the soft ground, increasing the shear strength. The high-pressure jet agitation method is a method in which after the ground is drilled to a predetermined depth using an injection rod, the injection rod mounted on the lower end of the injection rod is pulled up while rotating or swinging the injection rod, A method to form a cylindrical or fan-shaped ground improvement body by injecting the liquid in the horizontal direction with ultra-high pressure while agitating and mixing the hardened material liquid and the soft soil forming the ground while cutting the existing ground. It is.

  In the ground improvement by the high-pressure jet agitation method, the quality of the ground improvement body is generally confirmed by performing check boring after the ground improvement body has hardened. Specifically, continuity is confirmed with a specimen sampled by core boring 1-2 weeks after construction, and strength is confirmed after 28 days.

  However, the method of confirming after the ground improvement body has hardened requires a large-scale apparatus and has a problem that it takes a considerable time to collect a sample. Moreover, when it was confirmed that the designed strength was not satisfied, it was necessary to perform additional construction or another kind of auxiliary construction method.

  Therefore, immediately after the construction of the ground improvement body by the high-pressure jet agitation method, uncured improved soil is sampled from the ground improvement body, and this specimen soil is filled into a formwork to prepare a specimen, which can be accelerated in a short period of time. There has been proposed a method for estimating the strength of the ground improvement body from the strength of the specimen subjected to curing and after accelerated curing (for example, Patent Document 1). Patent Document 1 collects the improved soil (soil cement body) immediately after construction built by the ground improvement construction method to produce a specimen, and performs accelerated curing with warm water for 1-2 days on this specimen, There is disclosed a method for obtaining the strength of a specimen after accelerated curing and estimating the specimen strength after curing for a normal period from the specimen strength after accelerated curing using a relational expression obtained in advance.

JP 2000-346768 A

  Japanese Patent Application No. 6-183294 (Japanese Patent Laid-Open No. 8-49490) and Japanese Utility Model Publication No. 3-54891 disclose the collection of unhardened improved soil that has been built by the ground improvement construction method immediately after construction. It is described that the sample collection device described can be used. Further, it is described that a method of collecting improved soil at an arbitrary depth with a backhoe or the like may be used.

  However, when the sample collection device described in Patent Document 1 is used, there is a problem that only the improved soil at a specific position can be collected (see FIG. 11).

  As shown in FIG. 11, in the high pressure jet agitation method, the hardening rod liquid is horizontally introduced from the injection nozzle attached to the lower end of the injection rod while penetrating the injection rod to a predetermined depth and pulling it up while rotating or swinging. A ground improvement body is created by spraying in the direction with ultra high pressure. And since the sampling device described in patent document 1 is attached instead of pulling up the injection rod, it is improved soil in the vicinity where the injection rod has penetrated, that is, a hatched line in FIG. Only the improved soil in the indicated range could be sampled.

  Further, although it has been disclosed to use a heavy machine such as a backhoe to collect improved soil at an arbitrary depth, there is a problem that the work becomes large and cannot be easily performed.

  When estimating the strength of the ground improvement body by accelerated curing using the improved soil collected from the unhardened ground improvement body immediately after construction by the high-pressure jet stirring method, the strength estimated only from the sample collected from a specific point Can estimate the strength of that particular point, but is not suitable for estimating the strength of other points in the ground improvement body. In order to estimate the strength of the ground improvement body with high accuracy, it is desirable to comprehensively judge the strength data obtained from samples of improved soil collected from a plurality of arbitrary points.

  The present invention has been made in view of the above problems, and provides a method for easily and accurately estimating the strength of a ground improvement body formed by a high-pressure jet stirring method in a short period after construction. It is an object.

  In order to solve the above-mentioned problem, the strength estimation method of the ground improvement body of the present invention is agitated and mixed by injecting a hardening material liquid from an injection nozzle of an injection rod penetrated to a predetermined depth in the ground by a high-pressure injection agitation method. A method for estimating the strength of the ground improvement body formed by collecting the improved soil from the ground improvement body at a point away from the penetration position of the injection rod before the hardening material liquid is hardened. An injection rod penetrating step for penetrating the injection rod provided with a sampling rod provided with a sampling portion to perform into the ground, an improved soil collecting step for collecting improved soil of the ground improvement body from the sampling portion, and the improved soil collection A strength measurement sample preparation step for preparing a strength measurement sample from the improved soil collected in the step, and the strength measurement sample preparation step. Accelerated curing step for accelerating the prepared strength measurement sample, strength measurement step for measuring the strength of the strength measurement sample after the accelerated curing step, and strength of the strength measurement sample obtained by the strength measurement step And a strength estimating step for estimating the strength of the ground improvement body based on the above.

  According to the present invention, since the injection rod provided with the sampling rod provided with the sampling section for collecting the improved soil from the ground improvement body is penetrated into the ground, the ground improvement creation machine used for the construction of the ground improvement body, etc. It is possible to collect the improved soil of the ground improvement body using as it is. Thereby, the improved soil can be collected easily and reliably in a short time.

  Moreover, the strength estimation method of the ground improvement body of the present invention uses an injection rod in which the sampling rod and the injection rod other than the sampling rod can be detached and attached, and in particular, the injection rod used for the construction of the ground improvement body. Has an injection rod provided with an injection nozzle. In the injection rod penetration step, the injection rod is used with the injection rod removed and the sampling rod attached.

  In order to solve the above-mentioned problem, the strength estimation method of the ground improvement body of the present invention is agitated and mixed by injecting a hardening material liquid from an injection nozzle of an injection rod penetrated to a predetermined depth in the ground by a high-pressure injection agitation method. This is a method for estimating the strength of the ground improvement body that is created by the camera unit and the ground improvement that can photograph the inside of the ground at a predetermined distance from the penetration position of the injection rod before the hardening material liquid hardens. An injection rod penetrating step for penetrating an injection rod having a video sampling rod provided with a sampling unit for sampling improved soil from the body into the ground, and an image display step for displaying an image taken by the camera unit on a ground monitor An improved soil collecting step for collecting the improved soil of the ground improvement body from the sampling unit, and the improved soil collected by the improved soil collecting step A strength measurement sample preparation step for preparing a strength measurement sample, an accelerated curing step for accelerated curing of the strength measurement sample prepared by the strength measurement sample preparation step, and an intensity measurement sample after the accelerated curing step. It has a strength measurement step for measuring strength, and a strength estimation step for estimating the strength of the ground improvement body based on the strength of the sample for strength measurement obtained by the strength measurement step.

  According to the present invention, since the injection rod having the video sampling rod provided with the video sampling rod provided with the camera unit capable of photographing the ground and the sampling unit for collecting the improved soil from the ground improvement body is penetrated into the ground, the ground improvement body It is possible to collect the improved soil of the ground improvement body using the ground improvement creation machine etc. used for construction of the ground as it is, and to collect the improved soil reliably while checking the ground improvement body in the ground by the camera unit it can. Thereby, the improved soil can be collected easily and reliably in a short time.

  Moreover, the strength estimation method of the ground improvement body of the present invention uses an injection rod in which a video sampling rod and an injection rod other than the video sampling rod can be attached and detached, and was used particularly for the creation of a ground improvement body. The injection rod has an injection rod provided with an injection nozzle. In the injection rod penetration step, the injection rod is removed and the injection rod with the video sampling rod attached is used.

  According to the present invention, since the injection rod in which the video sampling rod and the injection rod other than the video sampling rod are detachable and separable is used, the video sampling is performed on the injection rod used for the construction of the ground improvement body that has been conventionally used. By simply connecting the rods, the improved soil of the ground improvement body can be collected. Further, even when a defect occurs in the video sampling rod, repair and replacement can be easily performed by removing only the video sampling rod from the injection rod.

  Further, according to the strength estimation method for the ground improvement body of the present invention, the improved soil collecting step collects the improved soil at different positions within the design range of the ground improvement body.

  According to the present invention, the improved soil is sampled from a plurality of different positions within the design range of the ground improvement body to prepare a sample for strength measurement, and this is accelerated and cured to measure the strength. In addition, the strength can be estimated with high accuracy over the entire ground improvement body. As a result, even if a location that does not satisfy the design strength is found within the design range of the ground improvement body, measures such as re-construction can be taken immediately, and additional construction and other types of auxiliary construction methods are performed after the completion of the construction period. Things don't happen.

  In addition, the injection rod provided with the camera part penetrates to the deep part, and by confirming the presence of the curing material liquid based on the respective images taken at a plurality of points, not only the effective diameter of the improved body but also the continuous The property can also be reliably confirmed immediately after construction. As a result, even if a problem is found in the continuity of the ground improvement body, it is possible to immediately take measures such as re-construction, and a situation where additional construction or another kind of auxiliary construction method is performed after the completion of the construction period Does not occur.

  Furthermore, since the injection rod with the camera and sampling parts is inserted into the soft mud-like ground improvement body before the hardening material liquid hardens, the ground improvement can be done easily in a short time without requiring a large force. The injection rod can penetrate to the deepest part of the body. In addition, the inserted injection rod can be pulled up easily and in a short period of time. By moving to another position and inserting the injection rod, multiple locations of improved soil can be reliably collected in a short time. can do.

  Further, according to the strength estimation method of the ground improvement body of the present invention, the injection rod further includes a colorant spray port for spraying the colorant in the vicinity of the camera unit, and the image display step includes supplying the hardening material liquid from the colorant spray port. A coloring step of spraying a coloring agent that is colored so as to be distinguishable from earth and sand to color the hardening material liquid is included. In the image display step, an image of the colored hardening material liquid is displayed on the monitor.

  According to the present invention, since the colorant spraying port for spraying the colorant is provided in the vicinity of the camera unit, the curable material liquid in the region captured by the camera unit can be reliably captured even with a small amount of colorant. be able to. Thereby, cost reduction of a coloring agent can be achieved. Further, since the curable material liquid is colored so as to be distinguishable from the earth and sand, even when it is difficult to distinguish the earth and sand and the curable material liquid in the image, the colored curable material liquid can be reliably displayed. Thereby, it is possible to grasp the presence of the hardening material liquid and reliably collect the improved soil.

  Further, according to the strength estimation method of the ground improvement body of the present invention, the sampling portion is provided inside the video sampling rod, communicates with the improved soil storage portion capable of storing the improved soil, the improved soil storage portion, and improves the ground. An improved soil inflow pipe into which the improved soil collected from the body flows, and an opening in communication with the improved soil inflow pipe and provided with a sampling shutter on the side wall of the injection rod, the injection rod is a design of the ground improvement body After reaching a predetermined position within the range, the improved soil can be stored in the improved soil storage portion by opening the sampling shutter.

  According to the present invention, since the opening is opened by opening the sampling shutter after the injection rod reaches the target position within the design range of the ground improvement body, the improved soil at the target position can be reliably collected. And improved soil other than the target position is not mixed. Therefore, a strength measurement sample is prepared from the collected improved soil, and this is accelerated and cured to measure the strength, whereby the strength of the improved body at the collected position can be estimated with high accuracy.

  Further, the strength estimation method of the ground improvement body according to the present invention is such that the video sampling rod includes the improved soil downstream portion having the improved soil storage portion and the improved soil inflow pipe, the opening portion and the improved soil inflow. In the state where the improved soil upstream portion having a part of the pipe is detachable and separable, and the improved soil downstream portion and the improved soil upstream portion are connected, the improved soil inflow pipe and the improved soil upstream portion of the improved soil downstream portion are connected. The improved soil inflow pipe is connected.

  According to the present invention, the sampling portion of the video sampling rod includes the improved soil storage portion and the improved soil downstream portion having a part of the improved soil inflow pipe, and the improved soil upstream portion having a portion of the opening and the improved soil inflow pipe. Can be detached and moved, and after the improved soil is stored in the improved soil storage part, only the improved soil downstream part of the sampling part can be separated and moved to be used for the preparation of a sample for strength measurement. Even when the improvement soil is clogged in the inflow pipe, the clogging can be easily eliminated.

  In the ground improvement method according to the present invention, the position sensor is provided in or near the video sampling rod, and the position sensor detects the tilt angle and the tilt direction of the injection rod in the ground. A tilt detector and an azimuth meter are provided, and a position detecting step for detecting the position of the video sampling rod in the ground using the tilt angle information and the tilt azimuth information obtained from the tilt meter and the azimuth meter is included.

  According to the present invention, when passing through the normal ground from the ground surface to the upper end of the ground improvement body, there may be a deviation in inclination and azimuth, the deviation that occurred at this position after reaching the ground improvement body, As the depth gets deeper, the difference gradually increases. According to the present invention, since the position sensor is provided in or near the video sampling rod, the position of the video sampling rod in the ground can be detected three-dimensionally. Therefore, even if the penetration direction of the video sampling rod deviates from the vertical direction, it is possible to grasp three-dimensionally in which direction and how much the improved soil is sampled. Therefore, it is possible to prevent a decrease in accuracy due to a shift in the sampling position and maintain high accuracy.

  According to the strength estimation method of the ground improvement body of the present invention, it is possible to provide a method capable of easily and accurately estimating the strength of the ground improvement body formed by the high-pressure jet stirring method in a short period after construction. .

It is a schematic block diagram of the ground improvement body formation apparatus used for creation of the ground improvement body in one Embodiment of this invention. It is a side view of the injection rod provided with the nozzle. It is a figure explaining the flow path etc. in a connecting rod. It is a schematic block diagram of the improved soil sampling apparatus which extract | collects the improved soil of the ground improvement body in one Embodiment of this invention. (A) It is a front view of a video sampling rod. (B) It is side surface partial sectional drawing of a video sampling rod. (A) It is a figure which shows the opening part vicinity of a sampling rod. (B) It is a figure which shows the AA cross section of Fig.6 (a). (A) It is a figure which shows the camera part vicinity of a camera part rod. (B) It is a figure which shows the BB cross section of Fig.7 (a). It is a figure which shows CC cross section of FIG.5 (b). It is a schematic block diagram of the ground improvement body formation apparatus used for the strength estimation method of the ground improvement body of the modification of this invention. It is a flowchart of the strength estimation process of the ground improvement body in one Embodiment of this invention. It is a figure which shows the extractable range of the conventional improved soil.

  Hereinafter, an embodiment of a strength estimating method for a ground improvement body according to the present invention will be described with reference to the drawings. The present invention is a method for estimating the strength of a ground improvement body created by a high-pressure jet agitation method within a short period of time after the construction of the ground improvement body, and the improved soil at any position within the design range of the ground improvement body. Since it is possible to collect, the strength can be estimated with high accuracy over the entire ground improvement body. The “improved soil” is intended to include earth and sand, a hardening material liquid, and a mixture of earth and sand and a hardening material liquid existing within the design range of the ground improvement body. The “arbitrary position within the design range of the ground improvement body” means a point at an arbitrary depth at an arbitrary point on the ground surface within the planned range where the designed ground improvement body exists in the ground.

  FIG. 1 is a schematic configuration diagram of a ground improvement body creation device used for creation of a ground improvement body in one embodiment of the present invention, and FIG. 2 is a side view of an injection rod provided with a nozzle.

  First, by using the ground improvement body forming apparatus 100, the ground improvement body is obtained by injecting a hardening material liquid from the injection nozzle 2 of the injection rod 1 penetrated to a predetermined depth in the ground by a high-pressure injection stirring method and stirring and mixing. A method of creating the above will be briefly described.

  As shown in FIG. 1, the injection rod 1 is composed of an injection rod 3 (see FIG. 2) provided at the tip and a connection rod 4 (see FIG. 3) connected to the injection rod 3. The injection rod 3 is provided with four tip nozzles 101 to 104 and an air injection port (not shown) at the tip, and from the four tip nozzles 101 to 104 and the air injection port (not shown) through the injection rod 1. The supplied water (liquid) and air are jetted. An injection nozzle 2 is provided on the side surface of the injection rod 3, and cement milk (hardening material liquid) supplied through the injection rod 1 is injected from the injection nozzle 2. The connecting rod 4 is a hollow perforated tube, which is sequentially connected when the injection rod 1 penetrates into the ground so that the injection rod 1 can penetrate to a deep position. Here, the injection rod 1 is not only the one in which the injection rod 3 and the connection rod 4 are connected, but the injection rod 3 is removed from the injection rod 1 provided with the injection rod 3 and the connection rod 4, and a video sampling rod to be described later The injection rod 1 including the video sampling rod 5 and the connecting rod 4 is included. As is clear from FIGS. 1 and 2, the injection rod 3 and the connecting rod 4 are detachably connected.

  The ground improvement and construction machine 6 is a machine that supports the injection rod 1 and moves the injection rod 1 up and down and rotates. Thereby, the injection rod 1 can be rotated as well as moved up and down by the ground improvement and construction machine 6. As described above, the injection rod 1 is provided with nozzles (injection nozzle 2 and tip nozzles 101 to 104) on the end and side surfaces, and a swivel 7 is attached to the rear end. And in the injection rod 1, the water flow path 14 and the air flow path for supplying cement milk, air, and water (liquid) to the injection nozzle 2, the tip nozzles 101 to 104, and the air injection port (not shown), respectively. 15 and a cement milk flow path 16 are provided (see FIG. 3). Here, FIG. 3 is a diagram illustrating a flow path and the like in the connecting rod.

  The swivel 7 is connected to water, air, and cement milk supply pipes 11, 12, and 13 (hose) respectively supplied from a water supply source 8, an air supply source 9, and a cement milk supply source 10. Air and cement milk (hardening material liquid) are supplied to a water flow path 14, an air flow path 15, and a cement milk flow path 16 provided in the injection rod 1. Thus, the cement milk, air, and water respectively supplied from the water supply source 8, the air supply source 9, and the cement milk supply source 10 are supplied from the supply pipes 11 to 13, the swivel 7, and the flow paths 14 to 14, respectively. 16, and is ejected from nozzles (injection nozzle 2, tip nozzles 101 to 104) and the like.

  Thus, cement milk is injected from the injection nozzle 2 provided on the side surface of the injection rod 1, and cement milk and water (liquid) are supplied from the tip nozzles 101 to 104 and the air injection port (not shown) provided at the tip. By being sprayed, it is possible to form a cylindrical, fan-shaped, wall-like, or grid-like ground improvement body in the ground.

  Next, an apparatus for collecting the improved soil at an arbitrary position within the design range of the ground improvement body created using the high-pressure jet stirring method will be described. FIG. 4 is a schematic configuration diagram of an improved soil collecting device that collects improved soil of the ground improvement body in one embodiment of the present invention. In the improved soil collecting device 106 shown in FIG. 4, the ground improvement generator 6 of the ground improvement body generating device 100 shown in FIG. 1 is used.

  As shown in FIG. 4, when collecting the improved soil within the design range of the ground improvement body, the injection rod 1 includes the connection rod 4, the video sampling rod 5, and the tip bit 17. The injection rod 1 composed of the connecting rod 4, the video sampling rod 5 and the tip bit 17 removes the injection rod 3 from the injection rod 1 composed of the connection rod 4 and the injection rod 3 used for the construction of the ground improvement body, Instead, a video sampling rod 5 and a tip bit 17 are attached.

  The video sampling rod 5 includes a camera unit rod 20 having a camera unit 18 and a colorant spraying port 19, and a sampling rod 22 having a sampling unit 21 (see FIG. 5). Here, FIG. 5A is a front view of the video sampling rod, and FIG. 5B is a partial side sectional view of the video sampling rod.

  The sampling unit 21 includes an improved soil downstream part 37 having a part of the improved soil storage part 28 and the improved soil inflow pipe 29, and an improved soil upstream part 38 having a part of the opening 31 and the improved soil inflow pipe 29. The improved soil downstream portion 37 and the improved soil upstream portion 38 of the sampling rod 22 are configured to be detachable and detachable. In the state where the improved soil downstream portion 37 and the improved soil upstream portion 38 are connected, the improved soil inflow pipe 29 of the improved soil downstream portion 37 and the improved soil inflow pipe 29 of the improved soil upstream portion 38 communicate with each other. Moreover, the camera part rod 20 which has the camera part 18 of the video sampling rod 5, the coloring agent spraying port 19, and the sampling rod 22 which has the sampling part 21 are comprised so that attachment or detachment is possible.

  A sampling shutter 30 is provided in the opening 31 of the sampling unit 21. The sampling shutter 30 is supported by two air cylinders 39 (see FIG. 6). The air cylinder 39 is connected to the air supply source 9 by the air supply hose 32 via the sampling shutter opening / closing switch 33. When the sampling shutter opening / closing switch 33 is turned “ON”, the air cylinder 39 is extended and the sampling shutter 30 is opened. When the sampling shutter opening / closing switch 33 is “OFF”, the sampling shutter 30 is closed. Here, FIG. 6A is a view showing the vicinity of the opening of the sampling rod, and FIG. 6B is a view showing the AA cross section of FIG. 6A.

  The camera unit rod 20 is provided with a camera unit 18 and a colorant spraying port 19 (see FIG. 7). Here, Fig.7 (a) is a figure which shows the camera part vicinity of a camera part rod, FIG.7 (b) is a figure which shows the BB cross section of Fig.7 (a).

  The camera unit 18 captures an image of the ground, and is connected to a ground monitor (display unit) 24 by a camera cable 23. Thereby, the image of the hardening material liquid etc. in the ground image | photographed with the camera part 18 can be confirmed on the ground.

  The camera unit 18 includes a camera 40 capable of photographing the ground, a light source 41, and a window 42 (see FIG. 7B). One light source 41 is disposed on each side of the camera 40, and the light emitted from the light source 41 irradiates the outer earth and sand through the window 42, and the camera 40 captures the area irradiated with the light. Thereby, it becomes possible to visually observe the state of earth and sand in the ground with the monitor 24 on the ground. Here, the image photographed by the camera 40 is displayed on the ground monitor 24 as a still image or a moving image. The window 42 is made of a transparent material (for example, sapphire) that is difficult to be damaged because the outside contacts the earth and sand.

The colorant spraying port 19 sprays a colorant and is provided in the vicinity of the lower part of the camera unit 18. The colorant spray port 19 is connected to a colorant supply pump switch 26 by a colorant supply hose 25 via a colorant tank 27. When the colorant supply pump switch 26 is turned “ON”, the colorant in the colorant tank 27 is sprayed from the colorant spraying port 19, and the image of the curing material liquid colored by the colorant is displayed on the ground. It is displayed on the monitor 24.
Here, since the curing material liquid becomes alkaline, a pH indicator can be used as a colorant. The pH indicator is suitable as a colorant used in a method of coloring a narrow range and photographing immediately after coloring. Preferable pH indicators in the present invention include phenolphthalein. Phenolphthalein is colorless in the acidic and neutral regions and red in the alkaline region, so the region where the hardener liquid containing cement-based solidification material and earth and sand are mixed is colored red, and the hardened material containing cement-based solidification material. The earth and sand in the area where the material liquid has not reached is not colored. In addition, since phenolphthalein exhibits a red color instantaneously in an alkaline atmosphere, it is not necessary to consider the time lag until coloring. Therefore, it is possible to easily and reliably confirm the presence of the curing material liquid in the photographed image immediately after the phenolphthalein spraying.

  The tip bit 17 has a conical shape and is attached to the tip of the injection rod 1. The tip bit 17 is provided with a water jet port 34 for jetting water at the tip, and water supplied from the water supply source 8 is jetted through a water supply hose 35 and a water channel 36 (see FIG. 8). It is sent to the mouth 34 and injected outside. Thereby, the ground is cut and the injection rod 1 can be inserted into the ground. Here, FIG. 8 is a diagram showing a cross section taken along the line CC in FIG.

  In the present embodiment, the mode of using the injection rod 1 including the connection rod 4 and the video sampling rod 5 when collecting the improved soil within the design range of the ground improvement body has been described. The injection rod 1 in which the injection rod 3 and the video sampling rod 5 are sequentially connected to the connection rod 4 may be used when creating the ground improvement body and when collecting improved soil within the design range of the ground improvement body. Thus, by using the injection rod 1 in which the injection rod 3 and the video sampling rod 5 are connected to the connecting rod 4, a ground improvement body can be created and the improved soil of the ground improvement body can be collected as it is (see FIG. 9). FIG. 9 is a schematic configuration diagram of a ground improvement body generating device used in a method for estimating the strength of a ground improvement body according to a modification of the present invention.

  Next, the strength estimation method of the ground improvement body of this invention is demonstrated using FIG. FIG. 10 is a flowchart of the strength estimating process of the ground improvement body in one embodiment of the present invention.

[Ground improvement body creation step]
First, in S1, after the ground is drilled to a predetermined depth using the injection rod 1, the injection rod 2 is lifted while rotating or swinging, and the injection nozzle 2 attached to the lower end of the injection rod 1 is used. The existing ground is cut by spraying the hardened material liquid in the horizontal direction with ultra-high pressure, and the hardened material liquid and the soft soil forming the ground are agitated and mixed to form a cylindrical or fan-shaped ground improvement body. (High-pressure jet stirring method (see FIG. 1)). In this ground improvement body creation step, an injection rod 1 comprising an injection rod 3 provided with an injection nozzle 2 and a connecting rod 4 is used. In addition, since the strength estimation method of the ground improvement body of the present invention is performed on the premise that the ground improvement body is formed, the ground improvement body formation step is particularly included in the strength estimation method of the ground improvement body of the present invention. It does not have to be.

[Injection rod penetration step]
Next, the injection rod 1 is inserted into a predetermined position by S2. The injection rod 1 is penetrated before the hardening material liquid is hardened, and a point away from the position where the injection rod 1 is penetrated by the ground improvement body creation step (S1), that is, the improved soil of the ground improvement body. The injection rod 1 provided with the video sampling rod 5 provided with the camera unit 18 capable of photographing the ground and the sampling unit 21 for collecting the improved soil from the ground improvement body at the desired position to collect the ground is in the ground. (See FIG. 4), and through the normal ground until the tip of the video sampling rod 5 reaches the target depth, the connecting rod 4 is connected in succession. At that time, water is sprayed from the water injection port 34 of the tip bit 17 provided at the tip of the injection rod 1 until just before passing through the normal ground, the ground is drilled, and thereafter, a force is applied downward in the ground. The injection rod 1 is penetrated. Here, when the injection rod 1 penetrates, the ground improvement construction machine 6 used for the construction of the ground improvement body is used, and the injection rod 1 composed of the tip bit 17, the video sampling rod 5 and the connection rod 4 is used. It is done.

[Image display step]
Next, the image in the ground is displayed on the monitor 24 by S3. The image display (S3) of the hardening material liquid in the ground is performed in parallel with the penetration of the injection rod 1 described above. That is, in the image display, the image taken by the camera unit 18 provided on the injection rod 1 is displayed on the ground monitor 24 while the injection rod 1 penetrates into the ground. Here, in the present embodiment, in order to display an image of the curable material liquid on the monitor 24, the curable material liquid and the curable material liquid are introduced from the colorant spraying port 19 provided near the lower portion of the camera unit 18 while penetrating the injection rod 1. A colorant for distinguishing from earth and sand is sprayed (coloring step) to color the hardening material liquid. Thus, since the colorant spraying port 19 is provided in the vicinity of the lower part of the camera unit 18, the colorant is sprayed from the colorant spraying port 19 while the injection rod 1 is inserted, and then the colorant is sprayed. Since the camera unit 18 moves to the place, an image of the colored curable material liquid can be reliably displayed on the monitor 24 even with a small amount of colorant. In addition, although this embodiment demonstrated the aspect which sprays a coloring agent when penetrating the injection rod 1, not only this but you may make it spray a coloring agent when extracting the injection rod 1. FIG. In this case, the colorant spray port 19 is provided in the vicinity of the upper portion of the camera unit 18. In the present embodiment, in the image display of the hardening material liquid or the like, a colorant for distinguishing the hardening material liquid and the earth and sand is sprayed from the colorant spraying port 19 provided in the injection rod 1 (coloring step). However, you may carry out in the aspect which does not spray a coloring agent especially.

[Improved soil collection step]
Next, the improved soil is collected by S4. The sampling of the improved soil of the ground improvement body is performed by the sampling unit 21 of the sampling rod 22. More specifically, after the injection rod 1 reaches a predetermined position within the design range of the ground improvement body, that is, after reaching the desired position for sampling the ground improvement material of the ground improvement body, the sampling shutter opening / closing switch 33 is turned on. As a result, the sampling shutter 30 is opened. Since the sampling shutter 30 is opened upward, the improved soil enters the sampling unit 21 from the opening 31 when the injection rod 1 is pulled up, and the improved soil that has entered from the opening 31 passes through the improved soil inflow pipe 29. The improved soil storage unit 28 flows into the improved soil storage unit 28, and the improved soil storage unit 28 stores the improved soil. When it is determined that a desired amount of improved soil has been stored in the improved soil storage unit 28, the sampling shutter 30 is closed by turning off the sampling shutter open / close switch 33. The amount of the improved soil stored in the improved soil storage unit 28 may be obtained by arranging a plurality of pressure sensors (not shown) in the improved soil storage unit 28 and changing the pressure of each pressure sensor. . That is, there is no flow of the improved soil in the portion where the improved soil in the improved soil storage portion 28 is stored, and the pressure of the portion in contact with the improved soil in the improved soil storage portion 28 is increased. Using this property, the amount of the improved soil in the improved soil storage unit 28 can be determined.

  After the collection of the improved soil is finished, the injection rod 1 is pulled up to the ground. Then, the improved soil downstream portion 37 of the video sampling rod 5 is removed from the other injection rods 1, the vinyl chloride hollow tube 43 in the improved soil storage portion 28 is pulled out from the improved soil storage portion 28, and the hollow tube 43 Take out the improved soil (see Fig. 4). As described above, since the video sampling rod 5 has no opening other than the opening 31, no improved soil other than the target position is mixed when the injection rod 1 is pulled out.

[Sample preparation step for strength measurement]
Next, a sample for strength measurement is prepared in S5. In the production of the sample for strength measurement, the sample for strength measurement is produced by filling the mold with the improved soil collected in the improved soil collection step. The size and shape of the mold are not particularly limited, but if a strength measurement sample based on the standard is required in the strength measurement step described later, the strength measurement sample is prepared according to the standard. For example, when a uniaxial compression test is performed in the strength measurement step, a sample for strength measurement (specimen) having a diameter of 5 cm × a height of 10 cm, a diameter of 4 cm × a height of 8 cm, and a diameter of 3.5 cm × a height of 7 cm can be produced. A formwork is preferably used. Examples of mold types include a cast iron split mold, an epoxy resin mold, a metal or paper bottomed cylindrical can, a vinyl chloride can, and the like. The sample for strength measurement is manufactured according to the Geotechnical Society standard "Test specimen preparation method (JGST
821) ”.

[Accelerated curing step]
Next, accelerated curing of the sample for strength measurement is performed by S6. In the accelerated curing of the strength measurement sample, the strength measurement sample prepared in the strength measurement sample preparation step is accelerated and cured. The accelerated curing can be performed, for example, by storing the sample for strength measurement in an electric drying furnace (electric constant temperature machine) or a warm water curing apparatus (constant temperature water tank) while keeping the form and applying temperature. In order to prevent drying of the strength measurement sample, it is preferable to seal the strength measurement sample with a resin film or to heat the strength measurement sample after placing it in a sealed container. The temperature to be added may be a temperature exceeding the standard curing temperature (20 ± 3 ° C.) of the concrete specimen. Preferably they are 30 to 80 degreeC, More preferably, they are 40 to 60 degreeC. The curing time is appropriately selected depending on the applied temperature. Specifically, for example, a method of curing for 20 to 24 hours with a warm water curing device set at 55 ° C can be mentioned.

[Strength measurement step]
Next, in S7, the strength of the strength measurement sample is measured. In the strength measurement of the strength measurement sample, the strength of the strength measurement sample after the accelerated curing step is measured. Return the sample for strength measurement after accelerated curing to room temperature, remove the mold, and measure the strength. Examples of the strength measurement test include a uniaxial compression test, an ultrasonic test, a split test, and a dynamic deformation test. The uniaxial compression test can be performed according to JIS A1216 “Soil uniaxial compression test method” or JIS A1108 “Concrete compression test method”. The ultrasonic test is a test for measuring a P wave and an S wave, and can be performed with reference to JGS 2110-1998 “Ultrasonic velocity measurement method by pulse transmission method”. The split test is a test for measuring the tensile strength, and can be performed with reference to JGS 2551-2002 “Method of testing tensile strength of rock by crushing”. The dynamic deformation test is a test for measuring dynamic properties (such as stiffness reduction and damping) and can be performed with reference to JGS 0542-2000 “Repeated Triaxial Test Method for Determining Deformation Characteristics of Ground Material”. it can.

[Strength estimation step]
Next, the strength of the ground improvement body is estimated by S8. The strength of the ground improvement body is estimated based on the strength of the specimen obtained in the hardness measurement step. In general, the strength of the ground improvement body is estimated using an equation obtained based on past accumulated data. The formula used for estimating the strength of the ground improvement body is obtained from the relationship between the specimen strength after curing for a normal period (for example, at 20 ° C. for 28 days) and the specimen strength after accelerated curing (see Patent Document 1). By applying the strength of the specimen obtained in the previous hardness measurement step to the above-described relational expression, the strength of the ground improvement body can be estimated. And the intensity | strength in the wide range of the ground improvement body of the planned place can be estimated by extract | collecting and performing the improvement soil in the different position within the design range of a ground improvement body.

  As described above, according to the present invention, it is possible to collect the improved soil at an arbitrary position within the design range of the ground improvement body created by the high-pressure jet stirring method, and easily and reliably the improved soil at the target position. Since it can be collected, the improved soil is collected from a plurality of different positions within the design range of the ground improvement body to prepare a sample for strength measurement, and this is accelerated and cured to measure the strength. Among them, it is possible to estimate the strength with high accuracy over the entire ground improvement body.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Next, a modified example of the present invention will be described.
(1) In this embodiment, although the aspect which has not detected the position of the injection | pouring rod 1 in the ground was demonstrated, not only this but the position of the injection | pouring rod 1, especially the sampling part 21 in a ground is detected. May be. For example, a position sensor can be provided in the vicinity (or inside) of the video sampling rod 5. This position sensor detects an inclination angle and an inclination direction (east, west, north and south) of the injection rod 1 in the ground, and an inclinometer for detecting an inclination angle and an inclination direction (east, west, north, and south) of the injection rod 1 respectively. And compass. Note that a position information transmission cable is connected to the position sensor, and information on an inclination angle and an inclination direction detected by the inclinometer and the azimuth meter is transmitted to a computer on the ground. The computer uses the transmitted tilt angle and tilt direction information and the length of the injection rod 1 from the ground to the sampling unit 21 (opening), and displays the position of the sampling rod 22 (sampling unit 21) on the monitor.

  Thereby, since the position sensor is provided in or near the video sampling rod 5, the position of the video sampling rod 5 in the ground can be detected three-dimensionally. Therefore, even when the penetration direction of the video sampling rod 5 is deviated from the vertical direction, it is possible to grasp three-dimensionally in which direction and how much the improved soil is sampled, and the target sampling position and It is possible to prevent a decrease in accuracy due to an actual sampling position shift and maintain high accuracy.

DESCRIPTION OF SYMBOLS 1 Injection rod 2 Injection nozzle 3 Injection rod 4 Connection rod 5 Video sampling rod 6 Ground improvement construction machine 7 Swivel 8 Water supply source 9 Air supply source 10 Cement milk supply source 11 Water supply pipe 12 Air supply pipe 13 Cement milk supply pipe 14 Water channel 15 Air channel 16 Cement milk channel 17 Tip bit 18 Camera unit 19 Colorant spray port 20 Camera unit rod 21 Sampling unit 22 Sampling rod 23 Camera cable 24 Monitor 25 Colorant supply hose 26 Colorant supply pump switch 27 Coloring Agent tank 28 Improved soil storage unit 29 Improved soil inflow pipe 30 Sampling shutter 31 Opening 32 Air supply hose 33 Sampling shutter open / close switch 34 Water injection port 35 Water supply hose 36 Water flow path 37 Improved soil downstream portion 38 Sat upstream portion 39 the air cylinder 40 camera 41 source 42 window 43 hollow tube 100 soil improvement material reclamation apparatus 101 tip nozzle 102 distal nozzle 103 distal nozzle 104 distal nozzle 106 modified soil sampling device

Claims (9)

A method for estimating the strength of a ground improvement body formed by injecting a hardening material liquid from an injection nozzle of an injection rod that has been penetrated to a predetermined depth in the ground by a high-pressure injection agitation method, and stirring and mixing,
Before the hardening material liquid is hardened, the injection rod having a sampling rod provided with a sampling portion for collecting improved soil from the ground improvement body at a predetermined distance from the penetration position of the injection rod in the ground An injection rod penetration step that penetrates into,
Improved soil collecting step for collecting improved soil of the ground improvement body from the sampling unit;
A strength measurement sample preparation step of preparing a strength measurement sample from the improved soil collected by the improved soil sampling step;
An accelerated curing step of accelerating and curing the strength measurement sample prepared by the strength measurement sample preparation step;
An intensity measurement step for measuring the intensity of the sample for intensity measurement after the accelerated curing step;
A strength estimation step for estimating the strength of the ground improvement body based on the strength of the strength measurement sample obtained by the strength measurement step;
Strength estimation method for ground improvement body having A method for estimating the strength of a ground improvement body formed by injecting a hardening material liquid from an injection nozzle of an injection rod that has been penetrated to a predetermined depth in the ground by a high-pressure injection agitation method, and stirring and mixing,
A video provided with a camera unit capable of photographing the inside of the ground and a sampling unit for collecting the improved soil from the ground improvement body at a predetermined distance from the penetration position of the injection rod before the curing material liquid is cured. An injection rod penetration step for penetrating the injection rod with a sampling rod into the ground;
An image display step of displaying an image captured by the camera unit on a ground monitor;
Improved soil collecting step for collecting improved soil of the ground improvement body from the sampling unit;
A strength measurement sample preparation step of preparing a strength measurement sample from the improved soil collected by the improved soil sampling step;
An accelerated curing step of accelerating and curing the strength measurement sample prepared by the strength measurement sample preparation step;
An intensity measurement step for measuring the intensity of the sample for intensity measurement after the accelerated curing step;
A strength estimation step for estimating the strength of the ground improvement body based on the strength of the strength measurement sample obtained by the strength measurement step;
Strength estimation method for ground improvement body having   The ground injection body strength estimating method according to claim 2, wherein the injection rod is configured such that the video sampling rod and an injection rod other than the video sampling rod can be attached and detached. The injection rod used for creating the ground improvement body has an injection rod provided with the injection nozzle,
4. The method for estimating the strength of a ground improvement body according to claim 3, wherein, in the injection rod penetrating step, the injection rod is removed and the injection rod attached with the video sampling rod is used.   The ground improvement object strength estimation method according to claim 2, wherein the improvement soil collection step collects improvement soil at different positions within a design range of the ground improvement object. The injection rod is
A colorant spraying port for spraying a colorant in the vicinity of the camera unit;
The image display step includes a coloring step of coloring the curing material liquid by spraying a coloring agent that colors the curing material liquid so as to be distinguishable from earth and sand from the colorant spraying port,
3. The method for estimating the strength of a ground improvement body according to claim 2, wherein in the image display step, an image of the colored curable material liquid is displayed on the monitor. The sampling unit
An improved soil storage unit provided inside the injection rod and capable of storing the improved soil;
An improved soil inflow pipe that communicates with the improved soil storage unit and into which the improved soil collected from the ground improvement body flows,
Communicating with the improved soil inflow pipe, and having an opening provided with a sampling shutter on the side wall of the injection rod,
3. The ground improvement according to claim 2, wherein after the injection rod reaches a predetermined position within a design range of the ground improvement body, the improved soil can be stored in the improved soil storage portion by opening the sampling shutter. Body strength estimation method.   The video sampling rod includes an improved soil having a part of the improved soil storage part and the improved soil inflow pipe, a part of the improved soil inflow pipe, the opening and a part of the improved soil inflow pipe. When the improved soil downstream portion and the improved soil upstream portion are connected to each other, the improved soil inflow pipe of the improved soil downstream portion and the improved soil inflow tube of the improved soil upstream portion are The strength estimating method for a ground improvement body according to claim 7, wherein the ground improvement body is communicated. A position sensor is provided in or near the video sampling rod;
The position sensor includes an inclinometer and an azimuth meter for detecting an inclination angle and an inclination direction of the injection rod in the ground, respectively.
The ground according to claim 2, further comprising a position detecting step of detecting the position of the video sampling rod in the ground using the tilt angle information and the tilt direction information obtained from the tilt meter and the compass. Strength estimation method for improved body.

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