JP7299138B2 - POSITION DETERMINATION SYSTEM OF GROUND SUPPORTING LAYER AND SOIL IMPROVEMENT METHOD - Google Patents

Description

The present invention relates to a ground support layer position determination system and a ground improvement method, and more particularly, a ground that can more reliably grasp the depth position of the support layer of the target ground without performing complicated processing on construction equipment. The present invention relates to a support layer position determination system and a ground improvement method using this system.

A CDM (Cement Deep Mixing) construction method is known for improving soft ground to firm ground by stirring and mixing soft soil and an improvement material to solidify the ground. In the CDM construction method, a ground improvement device equipped with a rotationally driven stirring blade is used (see, for example, Patent Document 1). This stirring blade is attached to a long rod and moves up and down in the ground. As the construction process, first, the ground is excavated to the depth of the support layer by moving the stirring blade downward in the ground while rotating. After that, while supplying the improvement material into the ground, the stirring blade is rotated and moved upward. As a result, the improvement material is injected into the ground and mixed to improve the ground.

Conventionally, when excavating the ground to the depth of the support layer, the depth position of the support layer is determined based on the torque required to rotate the stirring blades and the load acting on the processing machine that suspends the stirring blades. Indirectly estimated. Therefore, there is room for improvement in accurately grasping the depth position of the support layer. Since the improved ground is stabilized by being supported by the support layer, it is important to accurately grasp the depth position of the support layer when performing ground improvement work.

JP 2007-224645 A

An object of the present invention is to provide a ground support layer position determination system and a ground improvement method using this system that can more reliably grasp the depth position of the support layer of the target ground without performing complicated processing on construction equipment. is to provide

In order to achieve the above object, the ground support layer position determination system of the present invention is a ground support used in a ground improvement device in which a plurality of shafts equipped with stirring blades for stirring a target ground are placed adjacent to each other and vertically moved in an upright state. A layer position determination system, comprising: a cone penetration tester; a stirring blade monitor unit that grasps the position of the stirring blade in a plan view; and a control unit that receives data grasped by the stirring blade monitor unit , the probe of the cone penetration test device is arranged at a standby position above each of the stirring blades provided on at least two target shafts of the plurality of shafts, and cone penetration by the cone penetration test device When performing the test, the control unit based on the grasped data forms a moving region in which the probe can move downward without interfering with the respective stirring blades provided on the respective target shafts. The rotation angle position of the target shaft is controlled, and the cone penetration test is performed by moving the probe at the standby position downward through the stirring range of the target ground by each of the stirring blades, and this cone Based on the result of the penetration test, the depth position of the support layer of the target ground is grasped, and it is arranged above each of the stirring blades provided on each of the target shafts and moves up and down in the stirring range. The probe at the standby position is housed in the guide pipe so as to be retractable from the lower end opening of the guide pipe, and a cover material that closes the lower end opening of the guide pipe is provided, and when performing the cone penetration test The probe at the standby position is moved downward to penetrate the cover material and protrude downward from the lower end opening .

The ground improvement method of the present invention is characterized by forming an improved ground using the ground improvement device on the support layer whose depth position is grasped using the above-described ground support layer position determination system. .

According to the ground support layer position determination system of the present invention, at least for the ground improvement device, a cone penetration test device, a stirring blade monitor unit for grasping the position of the stirring blade in plan view, and the stirring blade A control unit to which data grasped by the monitor unit is input may be provided. Then, when performing a cone penetration test by the cone penetration test device, using the data grasped by the stirring blade monitor unit, the control unit causes the probe to interfere with each of the stirring blades provided on each of the target shafts. Since the rotation angle position of at least one target shaft is controlled so as to form a movement area that can be moved downward without moving, there is no need to perform complicated processing on construction equipment (soil improvement equipment). Then, the depth position of the support layer of the target ground is determined based on the results of actually conducting a cone penetration test by moving the probe downward through the stirring range of the target ground by each of the stirring blades. can be grasped with certainty.

According to the ground improvement method of the present invention, by forming the improved ground on the support layer of the target ground whose depth position is more reliably grasped, it is possible to ensure higher stability of the formed improved ground.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram illustrating a position determination system for a ground support layer according to the present invention; It is explanatory drawing which illustrates the vicinity of the stirring blade of FIG. 1 by the side view. FIG. 3 is a view taken along the line AA of FIG. 2; FIG. 4 is an assembly diagram illustrating the structure of the tip of the guide pipe; It is explanatory drawing which illustrates the preliminary|backup detection process of the depth position of a support layer. 6 is an explanatory diagram illustrating a state in which the stirring blades of FIG. 5 are moved upward; FIG. FIG. 5 is an explanatory diagram illustrating the position of each stirring blade in plan view when the rotation angle position of the target shaft is controlled. It is explanatory drawing which illustrates the process which is implementing a cone penetration test. FIG. 4 is an explanatory diagram illustrating a probe penetrating a cover material; FIG. 4 is a graph diagram illustrating the results of a cone penetration test; FIG. 9 is an explanatory diagram illustrating a state in which the probe in FIG. 8 is moved upward; It is explanatory drawing which illustrates the process of ground improvement construction. FIG. 4 is an explanatory diagram illustrating a process of discharging and mixing an improvement material onto a target ground; It is explanatory drawing which illustrates the formed improved ground. FIG. 5 is an explanatory diagram illustrating another embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION A ground support layer position determination system and a ground improvement method according to the present invention will be described below based on embodiments.

A ground support layer position determination system 1 (hereinafter referred to as a position determination system 1) of the present invention illustrated in FIGS. 1 to 3 is applied to a ground improvement device 7 that performs ground improvement work such as deep mixing treatment. . Then, the ground improvement method of the present invention improves the target ground B using the position determination system 1 of the present invention.

The ground improvement device 7 has a plurality of shafts 8A, 8B, 8C, 8D provided with stirring blades 9 for stirring the target ground B. A plurality of shafts 8A-8D are joined adjacent to each other and supported by a vertically extending mast 8M. These shafts 8A to 8D vertically move integrally along the tower 7a in an upright state. Each shaft 8A-8D is rotationally driven by a drive motor 8 attached to each shaft 8A-8D. Along with this, the stirring blades 9 attached to the respective shafts 8A to 8D are rotationally driven about the shaft axes of the attached shafts 8A to 8D.

Stirring blades 9 are attached to each of the shafts 8A to 8D at a plurality of vertically spaced positions. A plurality of stirring blades 9 are arranged on each shaft at intervals in the circumferential direction around the axis of the shaft. In this embodiment, the stirring blades 9 are attached to each of the shafts 8A to 8D at three vertically spaced locations, and two stirring blades 9 are arranged at equal intervals in the circumferential direction at each location. It is That is, six stirring blades 9 are attached to each shaft. The stirring blades 9 can be attached to a desired number of locations, not limited to three locations vertically spaced on each of the shafts 8A to 8D, and the number of stirring blades 9 arranged at each location is limited to two. can be any desired number. In addition, the intervals in the circumferential direction of the stirring blades 9 arranged at each location can also be set to desired intervals. The number of shafts 8A to 8D is not limited to four, and may be any desired number such as two, four, or eight.

The stirring blades 9 of the shafts 8A to 8D arranged adjacently overlap each other in a rotational operation range in plan view about the axis of each shaft. The stirring blade 9, the shafts 8A to 8D and the drive motor 8 are integrally raised and lowered by winding and unwinding the wire by the winch 10. FIG.

In each of the shafts 8A to 8D, a discharge port 9a is installed in the stirring blade 9 at a predetermined position (the uppermost position and the lowermost position in this embodiment). An improvement material C for ground improvement is supplied from a supply tank installed on the target ground B to the discharge port 9a. The discharge port 9a can be directly formed in the stirring blade 9, or the opening at one end of a supply pipe for the improving material C attached to the stirring blade 9 can be used as the discharge port 9a. A known material is used as the improving material C, and a specific example thereof is cement milk.

The position determination system 1 includes a cone penetration test device 2, a stirring blade monitor unit 3 that grasps the position of each stirring blade 9 in plan view, and a control unit 6 to which the grasped data by the stirring blade monitor unit 3 is input. I have. This embodiment further includes a guide pipe 4 arranged above each stirring blade 9, a cover material 5 for closing the lower end opening of the guide pipe 4, and a display 6a.

The cone penetration test device 2 has a probe 2a, a rod 2b connected to the upper end of the probe 2a, a probe advancing/retreating mechanism 2c, and a measuring section 2d. The probe 2a is a tip cone that is penetrated into the ground to be measured by the probe advance/retreat mechanism 2c. A hydraulic cylinder or the like is used for the probe advancing/retreating mechanism 2c. The measurement unit 2d measures data such as resistance (N value) when the probe 2a penetrates the ground. The cone penetration tester 2 is a known one, and for example, an electric cone penetration tester is used. In this embodiment, the probe 2a at the standby position is accommodated in the guide pipe 4 so as to be able to advance and retreat from the lower end opening 4a of the guide pipe 4. As shown in FIG.

The position of the probe 2a in plan view is set within the rotation operation range in plan view of each stirring blade 9 provided on at least two target shafts among the respective shafts 8A to 8D. As illustrated in FIG. 3, in this embodiment, the position of the probe 2a in plan view is set within the rotation operation range in plan view of each of the stirring blades 9 provided on the shafts 8A and 8B, and each of the shafts 8C and 8D is provided. is set outside the rotational operation range of the stirring blade 9 in plan view. Therefore, in this embodiment, the shafts of interest are shafts 8A and 8B.

In this embodiment, the probes 2a are arranged in standby positions above the respective stirring blades 9 of the shafts 8A to 8D, respectively, but the probes 2a are at least the respective stirring blades provided on the target shafts (shafts 8A and 8B). It suffices if it is arranged at a standby position above 9 . Therefore, for example, when the position of the probe 2a in plan view is set within the rotation operation range in plan view of each of the stirring blades 9 provided on the shafts 8A, 8B, 8C and 8D, the probe 2a is positioned on the shaft 8A to It is arranged at a standby position above each stirring blade 9 of 8D. The position of the probe 2a in plan view is within the rotational movement range of the respective stirring blades 9 provided on the shafts 8C and 8D and outside the rotational movement range of the respective stirring blades 9 provided on the shafts 8A and 8B. , the probe 2a is arranged at a standby position above at least the stirring blades 9 of the shafts 8C and 8D. Similarly, the guide pipe 4 may also be arranged at a standby position above at least the stirring blades 9 provided on the target shafts (shafts 8A and 8B).

As the stirring blade monitor unit 3, for example, an angle sensor is used for detecting the rotation angle (rotation angle position) of each of the shafts 8A to 8D about the shaft axis. In this embodiment, the position of each of the stirring blades 9 provided on all the shafts 8A to 8D is grasped in plan view. In this embodiment only the respective stirrer blades 9 provided on the shafts 8A and 8B) are sufficient.

Guide pipes 4 are fixed to mast 8M and extend along respective shafts 8A-8D. The guide pipe 4 moves up and down integrally with the respective shafts 8A-8D.

As illustrated in FIG. 4, a cover member 5 is detachably attached to the lower end opening 4a of the guide pipe 4 by means of an annular flange member 4b or the like. As the cover material 5, for example, a resin film or a rubber film that is pierced by the downwardly moving probe 2a is used.

The controller 6 and the display 6a are communicably connected by wire or wirelessly. Data input to the control unit 6, data calculated by the control unit 6, and the like are displayed on the display 6a.

Grasped data indicating the position of each stirring blade 9 in plan view grasped by the stirring blade monitoring unit 3 is sequentially input to the control unit 6 . The positions of the respective shafts 8A to 8D in plan view are known, the mounting positions of the respective stirring blades 9 on the respective shafts 8A to 8D, and the size and shape of the respective stirring blades 9 in plan view are also known. The planar view position and planar view size and shape of the probe 2a are also known. These known data are stored in the control section 6 . The control unit 6 calculates the position of each stirring blade 9 in plan view based on the input data detected by the stirring blade monitoring unit 3 and the stored data. The control unit 6 performs various arithmetic processing based on these data.

Next, an example of the procedure for judging the depth position of the target ground B by this position judgment system 1 will be described.

As exemplified in FIG. 5, the wire of the winch 10 is let out and the respective shafts 8A to 8D are rotated and moved downward as in the conventional case. As a result, the target ground B is stirred by the respective stirring blades 9 to form the stirring range Rm (the range of the two-dot chain line). In this step, the torque required to rotationally drive each of the shafts 8A to 8D (each of the stirring blades 9) and the load acting on the wire suspending each of the shafts 8A to 8D are sequentially detected. Based on these detection data, it is estimated whether or not the tips of the shafts 8A to 8D have reached the strong support layer B1.

When the torque becomes excessive or the load becomes too small, it is assumed that the tips of the shafts 8A to 8D have reached the support layer B1, and the depth position of the support layer B1 is preliminarily determined. to detect. The estimation of the depth position of this support layer B1 is the same as the conventional method.

Next, as illustrated in FIG. 6, the wire of the winch 10 is wound up and moved upward to a predetermined position while rotating the respective shafts 8A to 8D. As a result, the target ground B is further stirred by the respective stirring blades 9 .

A cone penetration test is then performed. At this time, the control unit 6 controls the rotation angle position of at least one of the target shafts 8A and 8B based on the grasped data grasped by the stirring blade monitor unit 3, and rotates the respective shafts 8A to 8D. to stop.

More specifically, as illustrated in FIG. 7, the control unit 6 forms a moving region Z in which the probe 2a in the standby position can move downward without interfering with the stirring blades 9 provided on the respective target shafts 8A and 8B. , the rotation angle position of the target shaft 8A, the target shaft 8B, or the target shafts 8A and 8B is controlled to stop the rotation. The positions of the stirring blades 9 provided on the target shafts 8A and 8B in a plan view can be visually grasped by displaying them on the display 6a.

When the positions of the stirring blades 9 provided on the target shafts 8A and 8B in plan view are in the state illustrated in FIG. 3, the probe 2a at the standby position interferes with the stirring blades 9 provided on the target shafts 8A and 8B. Cannot move downward. Therefore, in the present invention, the position of the target stirring blade 9 in a plan view is grasped. It is preferable to control the rotation angle position of at least one of the target shafts 8A and 8B so that the planar view area of the moving region Z is maximized.

Next, as illustrated in FIG. 8, the probe 2a at the standby position is moved downward through the stirring range Rm by each stirring blade 9 (each stirring blade 9 of the target shafts 8A and 8B) to perform a cone penetration test. I do. More specifically, the probe 2a is moved downward by pressing the rod 2b downward by the probe retraction mechanism 2c. The downwardly moving probe 2a breaks through the cover material 5 and protrudes downward from the lower end opening 4a of the guide pipe 4 through the cover material 5, as illustrated in FIG. Through holes 5 a are thereby formed in the cover member 5 . The probe 2a moving further downward passes through the stirring range Rm by each stirring blade 9 (each stirring blade 9 of the target shafts 8A and 8B), and a cone penetration test is performed.

In the cone penetration test, as illustrated in FIG. 10, test data D of the tip resistance q acting on the probe 2a is measured by the measuring section 2d. When the probe 2a breaks through the cover material 5 (at the depth position d1), the tip resistance q increases slightly, and when the probe 2a reaches the support layer B1 after that, the tip resistance q greatly increases. The amount of downward movement of the probe 2a from the standby position is grasped by the measuring section 2d. Further, the depth of the standby position is input to the control unit 6 based on the length of the wire drawn out from the winch 10 and the like. Therefore, the depth position d2 of the support layer B1 is grasped based on the result of this cone penetration test. After the cone penetration test is performed, the probe 2a is moved upward via the rod 2b by the probe advancing/retreating mechanism 2c and accommodated in the guide pipe 4, as illustrated in FIG.

As described above, according to this position determination system 1, at least the cone penetration test device 2, the agitating blade monitor unit 3, and the agitating blade monitor unit 3 Grasp data are input to the ground improvement device 7 A control unit 6 may be provided. When performing the cone penetration test, the control unit 6 uses the data grasped by the impeller monitor unit 3 to set the rotation angle position of at least one of the target shafts 8A and 8B so as to form the movement region Z described above. Since it is sufficient to control, there is no need to perform complicated processing on the ground improvement device 7. It can be applied to the existing soil improvement device 7 without great difficulty.

Since the depth position d2 of the support layer B1 is based on the results of an actual cone penetration test, it can be grasped more reliably. Further, during the cone penetration test, the probe 2a is moved downward through the stirring range Rm that is relatively softened by stirring, so the load on the probe 2a (cone penetration test device 2) can be reduced.

Furthermore, by comparing the depth position of the support layer B1 estimated in the process illustrated in FIG. 5 and the depth position d2 grasped by the position determination system 1, the validity of the grasped depth position d2 can be determined. . That is, the depth position of the support layer B1 can be determined by double-checking the depth position of the support layer B1 estimated by the conventional method and the depth position d2 of the support layer B1 grasped by the position determination system 1.

In this embodiment, since the guide pipe 4 is provided, the probe 2a and the rod 2b are protected. Therefore, the probe 2a can be easily moved up and down in the target ground B without being damaged.

In addition, by providing the cover material 5, earth and sand do not come into direct contact with the probe 2a when the guide pipe 4 is moved downward in the target ground B, which is more advantageous for protecting the probe 2a. Furthermore, since earth and sand do not enter the inside of the guide pipe 4, clogging of the probe 2a in the guide pipe 4 is avoided. Therefore, the probe 2a can be smoothly protruded from the guide pipe 4. As shown in FIG.

By using a resin film or a rubber film as the cover material 5, the through hole 5a of the cover material 5 formed by the probe 2a penetrating therethrough and the outer peripheral surface of the probe 2a can be sealed by the cover material 5. . As a result, even after the through hole 5a is formed in the cover material 5, even if the guide pipe 4 is moved up and down in the target ground B, it is advantageous for avoiding the entry of earth and sand into the inside of the guide pipe 4. Become.

After grasping the depth position of the support layer B1, ground improvement work is performed in earnest. Therefore, as illustrated in FIG. 12, the wire of the winch 10 is let out to rotate and move the shafts 8A to 8D downward. Each of the shafts 8A to 8D is moved downward to the grasped depth position d2 of the support layer B1. As a result, the target ground B is further stirred by the respective stirring blades 9 to form the stirring range Rm.

Next, as exemplified in FIG. 13, the wire of the winch 10 is wound up, and while the respective shafts 8A to 8D are rotated and moved upward, the improving material C is discharged from the discharge port 9a to improve the stirring range Rm. Inject material C. As a result, the earth and sand in the stirring range Rm and the improvement material C are stirred and mixed. It should be noted that the improving material C can also be discharged from the discharge port 9a in the process illustrated in FIG.

Through this process, the soft target ground B is improved to a strong improved ground R illustrated in FIG. 14 . This improved ground R is formed on the depth position that is accurately grasped as the position where the support layer B1 exists. That is, since the improved ground R is formed in a state of being directly placed on the strong support layer B1, high stability can be ensured.

In the above-described embodiment, the target ground B is land ground, but the target ground B can also be the water bottom ground of the sea or rivers and lakes. In this case, as exemplified in FIG. 15, the position determination system 1 and the ground improvement device 7 are mounted on a work boat 11 or the like. The procedure for grasping the depth position of the support layer B1 and the construction procedure for forming the improved ground R are the same as in the previous embodiment.

1 position determination system 2 cone penetration test device 2a probe (tip cone)
2b Rod 2c Probe advancing/retreating mechanism 2d Measurement unit 3 Stirring blade monitor unit 4 Guide pipe 4a Lower end opening 4b Flange member 5 Cover material 5a Through hole 6 Control unit 6a Display 7 Soil improvement device 7a Turret (leader)
8 Drive motors 8A, 8B, 8C, 8D Shaft 8M Mast 9 Stirring blade 9a Discharge port 10 Winch 11 Work ship B Target ground B1 Support layer Rm Stirring range R Improved ground C Improved material Z Moving area

Claims (3)

A position determination system for a ground support layer used in a ground improvement device in which a plurality of shafts equipped with stirring blades for stirring the target ground are placed adjacent to each other and vertically moved in an upright state,
Equipped with a cone penetration test device, a stirring blade monitor unit that grasps the position of the stirring blade in plan view, and a control unit that receives data grasped by the stirring blade monitor unit, the probe of the cone penetration test device is arranged at a standby position above each of the stirring blades provided on at least two target shafts out of the plurality of shafts,
When performing a cone penetration test by the cone penetration test device, the control unit determines a movement area in which the probe can move downward without interfering with each of the stirring blades provided on each of the target shafts based on the grasped data. a rotational angular position of at least one of said subject shafts is controlled to form;
The cone penetration test is performed by moving the probe at the standby position downward through the stirring range of the target ground by each of the stirring blades, and the target ground is supported based on the results of the cone penetration test. The depth position of the layer is grasped, the guide pipe is arranged above each of the stirring blades provided on each of the target shafts and moves up and down in the stirring range, and the probe at the standby position is housed in the guide pipe so as to be able to appear and retract from the lower end opening of the guide pipe, and is provided with a cover material that closes the lower end opening of the guide pipe, and when the cone penetration test is performed, the probe at the standby position is moved downward A position determination system for a ground support layer, characterized in that it penetrates the cover material and protrudes downward from the lower end opening . 2. The structure according to claim 1, wherein a resin film or a rubber film is used as the cover material, and a through hole of the cover material through which the probe penetrates and an outer peripheral surface of the probe are sealed by the cover material. Position determination system for ground bearing layers. A ground improvement method for forming an improved ground using the ground improvement device on the support layer whose depth position is grasped using the ground support layer position determination system according to claim 1 or 2 .

Images