JP2007009689A - Ground improvement method and ground improvement machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground improvement method having a high quality and excellent economical efficiency by actively changing fluidity at each treating depth. <P>SOLUTION: The ground improvement method mixes and agitates soil with a solidifier while excavating the present place ground. A mixing agitating head given a backhoe is penetrated into the ground and the ground is improved and treated as the ground improvement method. (a) The treating depth fluidity characteristic of treating ground is predetermined so that the fluidity of the treating ground is improved with the increase of the treating depth, a fluidity characteristic value as a target when the treating depth of an object region is specified is obtained from the characteristic and the fluidity of the treating ground immediately after treatment in the object region reaches the fluidity characteristic value in this case. (b) The rotational speed of a mixing agitating blade in the case of an actual mixing agitation is not made lower than half the rotational speed of the mixing agitating blade in the case of a non-loading. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention performs excavation of the current soil (raw soil) and mixing and stirring treatment while injecting a milky solidified material or a powdered solidified material mixed with water and a solidified material such as cement into the ground. The present invention relates to a ground improvement method for increasing the strength of the treated soil and a ground improvement machine used for the method.

  Determination of the amount of milky solidification material in the ground improvement method in which a milky solidification material kneaded in advance with a solidification material such as cement is mixed and stirred with the raw soil to be treated while being injected into the ground. Is an important factor in terms of processing quality, economy and workability. Therefore, in the past, the site soil (current soil or raw soil) to be treated was first collected, the amount of solidified material that would achieve the target strength was determined, and the mixing ratio with water was changed. Measure the strength of multiple milk-like solidified material patterns and create a correlation graph. Based on the graph, finally, you can achieve the target strength and obtain the most economical amount of solidified material. I want to ask.

For example, in Patent Document 1, as shown in FIG. 28, when the target strength of a specific raw soil to be treated is 160 kN / m ² , the mixing ratio W / of the water (W) and the solidified material (C). After empirically estimating the values of C as 70%, 90%, and 110%, respectively, the respective strengths were measured and graphed. From the graph, the amount of solidified material that can satisfy the target strength of 160 kN / m ² , 71 kg / m ³ is obtained when W / C = 70%, 93 kg / m ³ when W / C = 90%, and 111 kg / m ³ when W / C = 110%. And considering the workability and economic efficiency at the site, the strength development becomes more remarkable as the water content is smaller, so in many cases, the target strength can be achieved with the amount of solidified material with the smallest water content. As a result, 71 kg / m ³ when W / C = 70% is finally selected.

However, the determination of the amount of solidified material as described above is based solely on the target strength in the indoor soil test using the raw soil sample and faithfully reflects the depth of improvement and workability, etc. at the actual site. Therefore, in many cases, the actual construction is performed assuming that the strength of the room is about 75 to 50%.
Japanese Patent Application No. 2002-82436

  However, even if the amount of solidification material to be mixed is determined after collecting a sample of the raw soil as described above, the adhesiveness is too high depending on the actual properties of the raw soil at the site, and sufficient mixing and stirring can be performed. In particular, when the depth is greater than about 3 m, a restraint pressure due to earth pressure is also applied, and the mechanical load may be too large to perform sufficient mixing and stirring, resulting in uneven mixing, which may lead to quality deterioration. . On the other hand, it is not preferable to perform mixing and stirring so as to satisfy the required quality because it takes more time than necessary, which is uneconomical.

  The present invention has been made paying attention to such a problem. In consideration of the mechanical load due to ground improvement, an improved treatment depth-fluidity characteristic or an improved treatment depth-wet density-fluidity characteristic of the soil is determined in advance. In addition, by performing an improvement treatment so as to achieve the target fluidity characteristic value obtained from these characteristics, for example, the milk-like solidified material and the raw soil can be mixed and stirred uniformly, and by the mixing and stirring, It is intended to provide a ground improvement method and a ground improvement machine that do not require compaction as a post-treatment by setting the treated soil to a fluidized state.

  That is, in general, soil changes as “solid- (shrinkage limit) -semi-solid- (plastic limit) -plastic body- (liquid limit) -liquid” depending on the water content ratio, and the water content ratio is Even in a small and relatively stable state, it changes to soft soil that exhibits liquefaction as the water content ratio increases. This indicates that water content is the main factor governing soil mechanical properties. On the other hand, the ground improvement method that mixes and stirs with the raw soil while injecting the milk-like solidified material into the ground is generally treated later because the treated soil is fluidized by water replenishment by mixing and stirring with the milk-like solidified material. Although it is said that it is a construction method that does not require compaction of the treated soil as a treatment, as described above, depending on the soil properties of the raw soil, mixing unevenness and voids are inevitably generated.

  Therefore, the degree of hardness of the soil and the strength of the adhesion are ascertained from various properties such as the water content ratio and liquid limit of the soil obtained by soil tests, and no mechanical load is applied at each improvement depth according to the degree. It is an object of the present invention to improve the quality by actively fluidizing the treated soil immediately after mixing and stirring by increasing the amount of water contained in the milk-like solidified material to such an extent that fluidity can be secured.

  Furthermore, the fluidity is changed according to the depth in order to optimize the degree of mixing that most affects the strength expression of the treated soil by always fluidizing the treated soil, and the construction is performed under the most economical fluidity. An object of the present invention is to provide a ground improvement method and a ground improvement machine that are high quality and excellent in economic efficiency.

  According to the first aspect of the present invention, in the ground improvement method for increasing the strength of the current position soil by mixing and stirring with the solidified material while excavating the current position soil having a depth of 15 m or less, the tip of the arm of the construction machine functioning as a mother machine In addition, a mixing and stirring head equipped with a mixing and stirring blade that orbits in the vertical direction is installed, and the following conditions (a) and (b) are satisfied when the mixing and stirring head penetrates into the ground and is subjected to an improvement treatment. The improvement process is performed as described above.

  (A) As the relationship between the degree of fluidity of the treated soil immediately after the improvement treatment and the improvement treatment depth, which are considered to be favorable at least in terms of economy and workability, the fluidity of the treated soil increases as the improvement treatment depth increases. Thus, the improved processing depth-fluidity characteristic is determined in advance, and based on this improved processing depth-fluidity characteristic, a target fluidity characteristic value is obtained when the improved processing depth of the processing target area is designated, and processing is performed. The fluidity of the treated soil immediately after the improvement treatment in the target area should be the above fluidity characteristic value.

  (B) The average rotational speed of the mixing and stirring blade during actual mixing and stirring should not be less than one half of the rotational speed of the mixing and stirring blade during no load.

  In addition, the invention according to claim 2 is characterized in that, instead of the improved treatment depth-fluidity characteristic, the degree of fluidity of the treated soil immediately after the improved treatment and the improved treatment, which are good at least in terms of economy and workability. In relation to the depth, the fluidity of the treated soil increases as the depth of the improved treatment increases, and the fluidity of the treated soil increases as the wet density of the raw soil increases. Based on this improved treatment depth-wet soil wet density-fluidity characteristics, the target fluidity characteristics when the improved treatment depth and wet soil density of the target area are specified A value is obtained, and the improvement processing is performed so that the fluidity of the treated soil immediately after the improvement processing in the processing target region becomes the fluidity characteristic value.

  In this case, as an index indicating the degree of fluidity, for example, a flow value in a flow test (table flow test) in accordance with JIS R 5201, a slump value in accordance with a slump test in JIS A 1101, or a degree of viscosity, etc. Parameters can be used.

  Furthermore, at the time of actual construction, from the viewpoint of improving the quality of ground improvement processing, the improvement processing shall be performed with the addition amount of the solidifying material necessary to satisfy the target strength after the predetermined curing period has elapsed. In addition, as described in claims 3 and 4, it is desirable to perform the improvement process while measuring the revolution speed of the mixing stirring blade and the improvement processing depth by the mixing stirring head in real time.

  Moreover, in the invention of Claims 1-4, in performing a more efficient ground improvement process, as described in Claim 5, mixing stirring is carried out under the movement locus | trajectory of a substantially rectangular wave in planar view. It is assumed that the improvement process is performed by continuously moving the head.

  More specifically, as described in claim 6, the movement of the mixing and agitation head, which is a substantially rectangular wave-shaped movement locus, is a forward movement operation and a backward movement operation in the arm length direction in a plan view. The shift operation between the positions is set as one cycle, and these are repeated a plurality of cycles. The shift operation of the mixing and stirring head is performed within the processing width dimension of the mixing and stirring head in a plan view.

  In this case, whether the mixing and stirring head is continuously moved under a substantially zigzag movement locus in a plan view, instead of the movement locus having a substantially rectangular wave shape in a plan view, as described in claim 7. Further, as described in claim 8, the improvement processing may be performed by continuously moving the mixing and stirring head under a substantially N-shaped movement locus in plan view.

  Moreover, as the ground improvement machine used for the ground improvement construction method according to any one of claims 1 to 8, as described in claim 9, the improvement treatment depth by the mixing stirring head, the verticality of the mixing stirring head, and the mixing stirring It is desirable to have a means for measuring at least one of the circulatory speeds of the blades. In particular, the means for measuring the improved processing depth by the mixing and stirring head and the means for measuring the vertical degree of the mixing and stirring head are both. It is desirable to use together. Furthermore, as described in claim 10, it is more desirable to have both means for measuring the improvement processing depth by the mixing and stirring head, the verticality of the mixing and stirring head, and the circumferential speed of the mixing and stirring blade.

  According to the first and second aspects of the present invention, the improved treatment depth-fluidity characteristics or the improved treatment depth-wet density of the soil-fluidity characteristics are determined in advance, and the target flow obtained from these characteristics is determined. By performing the ground improvement process so that it has a fluidity characteristic value, that is, a fluidity characteristic value according to the improved treatment depth, the processing machine operates without any problem, so there is no variation in processing quality, and no mixing irregularities or voids are generated. In addition to improving the processing quality, a large amount of work per unit time can be secured, so that the economy is excellent and the cost can be reduced.

  In addition, according to the third and fourth aspects of the present invention, the processing quality is further improved by performing the improvement processing while measuring the circumferential speed of the mixing stirring blade or the improvement processing depth by the mixing stirring head.

  According to the fifth to eighth aspects of the invention, the mixing and stirring head, which is a processing machine, is moved in a substantially rectangular wave shape, zigzag shape or substantially N shape in a plan view in the ground to perform the improvement process. Thus, the work can be performed more efficiently than the conventional method in which the mixing and stirring head is repeatedly penetrated into the ground and pulled up repeatedly.

  According to the ninth and tenth aspects of the present invention, there is provided means for measuring at least one of the improved processing depth by the mixing and stirring head, the verticality of the mixing and stirring head, and the circumferential speed of the mixing and stirring blade. The improved processing depth and the degree of mixing and agitation are stabilized, and the processing quality is further improved. In particular, when a means for measuring the verticality of the mixing and agitation head is provided, construction with excellent vertical accuracy can be performed.

  1 to 5 show a construction system for ground improvement as a preferred embodiment of the present invention, and particularly FIGS. 1 to 3 show the overall structure of a ground improvement machine using a backhoe 1 as a base machine (base machine) as a construction machine. 4 and 5 show details of the structure, respectively. Although FIG. 1 and FIG. 2 are the same, they are divided into two drawings in order to avoid complication of the drawings.

  As shown in FIG. 1, at the tip of the arm 2 of the backhoe 1 that is a base machine, a hydraulic drive type mixing machine as a processing machine called a chain drive type so-called trencher type for excavating soil and mixing agitation. A stirring head 3 is detachably mounted.

  As shown in FIGS. 4 and 5, the trencher-type mixing and stirring head 3 wraps an endless drive chain 7 between a chain sprocket 5, which is the driving theory of the upper part of the frame 4, and a driven wheel 6 on the lower part, A plurality of mixing agitating blades 8, 8... Are mounted on the outer periphery of the drive chain 7 at an equal pitch, and a plurality of cutter blades 9 are projected from each mixing agitating blade 8 as shown in FIG. A solidified material discharge port 10 is provided at the front end of the frame 4 so that, for example, a slurry-like or powdery solidified material that has been pumped through a pipe 11 by a grout pump (not shown) or the like is discharged. . Then, by starting the hydraulic motor 12 provided at the upper part of the frame 4, the mixing stirring blades 8, 8... Move together with the drive chain 7, and at the same time, the mixing stirring head 3 is grounded by the thrust of the backhoe 1. By penetrating into the soil, excavation of the soil and mixing and stirring with the slurry-like solidified material or the powdery solidified material discharged from the solidified material discharge port 10 described above are performed.

  Here, a rotation sensor 13 such as a rotary encoder is provided coaxially with the hydraulic motor 12, and the rotation sensor 13 detects the rotation speed N (rpm) of the chain driving hydraulic motor 12. ing. The drive wheel for driving the drive chain 7 needs to be a chain sprocket 5 that meshes with the drive chain 7, but the driven wheel 6 does not necessarily need to be a chain sprocket.

  In the ground improvement method using the mixing and stirring head 3 as described above, first, the soil to be ground improvement is collected and subjected to a blending test in advance, and the target strength is achieved based on the graph of FIG. The water / cement ratio (W / C) required to do this is determined, and then the solidifying material addition amount, for example, the cement addition amount is determined. In addition, it cannot be overemphasized that this solidification material addition amount is a solidification material addition amount required in order to satisfy the target intensity | strength after predetermined curing period progress.

  Furthermore, the load of the trencher type mixing and agitating head 3 that controls the in-situ excavation and mixing and agitation processing as described above is always 65% or less regardless of the depth of the improvement processing depth to be constructed. Furthermore, the improvement process shall be performed by changing the fluidity of the treated soil immediately after the improvement process according to the improvement process depth. More specifically, Av represents the load resistivity of the mixing and stirring head 3 during mixing and stirring, B (m / sec) represents the circumferential speed of the mixing and stirring blade 8 when no load is applied, that is, the circumferential speed of the drive chain 7, and When the average speed of the drive chain 7 at C is C (m / sec), the load resistivity Av of the mixing and stirring head 3 calculated from the following formula (1) is reduced to 65% or less. The improvement treatment is performed by changing the fluidity of the treated soil immediately after the improvement treatment according to the treatment depth.

Av = {(BC) / B} × 100 (%) (1)
However,
Av: Load resistivity of the mixing agitation head during mixing agitation B: Circulation speed of the mixing agitation blade at no load C: Circulation average speed of the mixing agitation blade at the time of mixing agitation B (M / sec) is the following, assuming that the rotational speed of the hydraulic motor 12 detected by the previous rotation sensor 13 is N (rpm) and the circumferential dimension of the drive chain drive chain sprocket 5 is K (m). Calculated by equation (2).

B (m / sec) = (N × K) / 60 (2)
Further, the average rotational speed C (m / sec) of the drive chain 7 at the time of the above mixing and stirring varies due to the mixing and stirring resistance unlike the case of no load. For example, a trial run or the like is performed in advance for a predetermined time (for example, 10). The speed C1 (m / sec) of the drive chain 7 in minutes) is stored or recorded, and is calculated in advance as the average speed C (m / sec) of the drive chain 7 within the predetermined time. And

  In order to perform construction so that the value of the load resistivity Av of the mixing and stirring head 3 calculated by the above formula (1) satisfies the condition that it is 65% or less, the drive chain 7 (mixing and stirring blades) at the time of actual mixing and stirring is used. Since the construction is such that the rotational speed C1 of 8) is not less than half the rotational speed B (m / sec) of the drive chain 7 when there is no load, the actual speed will be described later. The rotation speed C1 of the drive chain 7 at the time of mixing and stirring is visually displayed in real time, for example, in the cabin of the backhoe 1, and the rotation speed C1 at the time of actual construction is shown to the operator as the rotation speed B (m / sec at no load). ) Encourage the construction work to be carried out without being less than half the size.

  More specifically, as shown in FIG. 3, for example, one area E (hereinafter referred to as one division) E divided into a rectangular shape having a width L and a length M in plan view is taken as one unit. When performing the ground improvement process, as shown in FIG. 6A, a so-called idling operation is performed in a state where the mixing and stirring head 3 is raised above the ground surface, and the mixing and stirring blade 8 is in a substantially no-load state. , 8... Are rotated together with the drive chain 7 and the peripheral speed B of the drive chain 7 at that time is measured based on the above equation (2). Here, it is assumed that, for example, 1.4 (m / sec) is measured as the circulation speed B.

  Next, with respect to the designated 1 division E, the actual construction is performed at a predetermined improvement processing depth as shown in FIG. 3B, and the processing for the predetermined division E (for example, 10 minutes) or 1 division E is performed. The actual rotational speed C1 (m / sec) of the drive chain 7 until the end is measured continuously in real time, and the value is stored or recorded. After that, after the work is finished, the lap average speed C (m / sec) is calculated. Here, it is assumed that the circular average speed C was 1.2 (m / sec).

Based on the values of the rotational speed B = 1.4 (m / sec) and the average rotational speed C = 1.2 (m / sec) of the drive chain 7 thus obtained, the above equation (1) is used for verification. Based on the above, the load resistivity Av of the mixing and stirring head 3 is calculated. That is, the load resistivity Av is Av = {(1.4−1.2) /1.4} × 100 = 14.3 (%)
It becomes.

  The value of load resistivity Av = 14.3% calculated here satisfies the requirement that the load resistivity Av is 65% or less as described above. In other words, from the above equation (1), even during the actual construction, care should be taken so that the rotational speed C1 of the drive chain 7 does not fall below one half of the rotational speed B of the drive chain 7 when there is no load. For example, the load resistivity Av always satisfies the requirement of 65% or less.

  Therefore, in the above example, in the subsequent actual construction, that is, the ground improvement process, it corresponds to a half of the rotation speed B of the drive chain 7 at no load as the construction condition for the operator = 1.4 (m / sec). The management target value of 0.7 (m / sec) is presented as the data to be processed, and the processing is instructed to be processed at the rotational speed of the drive chain 7 that is equal to or higher than the management target value. On the other hand, the rotational speed C1 of the drive chain 7 under construction is measured in real time and then displayed visually in the cabin of the backhoe 1 as will be described later. As a result, the operator visually confirms the visually displayed data. However, if the construction is carried out so that the management target value is 0.7 (m / sec) or more, the required load resistivity Av of the mixing and stirring head 3 can be satisfied.

  Furthermore, as a correlation between the improved treatment depth that would at least achieve both economic efficiency and workability during actual construction and the fluidity of the treated soil immediately after the improved treatment, the improved treated depth-fluidity characteristics as shown in FIG. This graph is prepared in advance. This graph is empirically determined from past construction data such as past construction results, that is, various soil types and improvement processing depths. The horizontal axis shows the improvement processing depth, and the vertical axis shows the flow immediately after the improvement processing. The flow value of the table test (conforming to JIS R 5201), which is an index of sex, is indicated. Here, the allowable lower limit value of the flow value at the improved processing depth of 3 m is set to 100 mm, and the allowable upper limit value is set to 140 mm. The allowable lower limit value of the flow value at the improved processing depth of 15 m is set to 180 mm, and the allowable upper limit value is also set. After setting the length to 220 mm, draw two parallel lines with a predetermined gradient so as to connect the allowable lower limit values and the allowable upper limit values, and within the range of the two parallel lines, an index of fluidity immediately after the improvement process Is set as an allowable range of flow values. As is clear from the figure, the fluidity of the treated soil immediately after the treatment is set higher as the improved treatment depth becomes larger.

  As can be seen from the graph of the figure, when the improvement processing depth is less than 3 m, the allowable range of the flow value is set to be the same as when the improvement processing depth is 3 m. In the case of exceeding 15 m, the allowable range of the flow value is set to be the same as that when the improvement processing depth is 15 m from the viewpoint of preventing breathing.

  And according to the depth of an actual construction location (the ground which is the target of ground improvement) in order to perform construction so as to satisfy the condition that the value of the load resistivity Av of the mixed stirring head 3 described above is 65% or less. The corresponding flow value is selected from the graph of FIG. 7, and the construction is performed by changing the fluidity of the treated soil immediately after the improvement processing for each improvement processing depth so as to satisfy the flow value condition. This selection of fluidity has priority over the amount of solidifying material added (cement added amount) based on the water / cement ratio (W / C) initially determined based on FIG. For example, when the improved processing depth is 15 m, the flow value is selected from the range of 180 mm to 220 mm as the flow value from the graph of FIG. 7, and the fluidity is adjusted using the median value of 200 mm as the target value.

  In other words, the fluidity immediately after the improvement treatment is positively changed according to the improvement treatment depth in order to optimize the mixing degree that has the greatest influence on the strength expression of the treatment soil by always fluidizing the treatment soil, and the most economical. Construction shall be performed under fluidity.

  By doing so, the mixing and stirring head 3 performs the mixing and stirring process without difficulty and stably, so that there is little variation in quality, and a large amount of work per unit time can be secured. Cost can be reduced.

  As a matter of course, when an extremely soft ground is to be constructed, it is assumed that the construction is performed by directly discharging the powdered solidified material into the ground instead of the slurry solidified material.

  In addition, in the case where the construction target location is rarely very soft ground, the required amount of solidifying material added may extremely increase when trying to satisfy the allowable range of the flow value of the graph shown in FIG. is expected. In such a case, emphasis is placed on economy, and as an exception, construction may be performed in a state where the flow value deviates upward from the allowable range of the graph shown in FIG.

FIG. 8 shows a correlation graph used in place of that of FIG. 7 as a modification of the present embodiment, and FIG. 7 shows the correlation between the improved processing depth and the table flow value that is an indicator of the fluidity of the treated soil. On the other hand, in FIG. 8, the table flow value which is an index of the improved processing depth and the fluidity of the treated soil, and the wet density ρt (t / m ³ ) which is an index of the physical properties (physical property values) of the raw soil The correlation is shown.

This graph is also empirically determined from past construction data, such as past construction results, that is, various soil types and improvement processing depths. The horizontal axis shows the improvement processing depth, and the vertical axis shows the immediately after the improvement processing. In addition to the flow value of the table test, which is an index of fluidity, the wet density ρt (t / m ³ ), which is a physical property value of the raw soil, is indicated.

  The flow value, which is an index of fluidity in actual construction, is preferably a high value that reduces the mixing agitation resistance from the viewpoint of workability (the mixing agitation resistance and the flow value of the treated soil are inversely proportional), and in terms of quality In order to improve the mixing and stirring property, it can be said that a higher value is desirable as the flow value (the flow value of the treated soil is directly proportional to the workability). However, in order to satisfy the target strength at a higher flow value, a large amount of solidifying material is used, which is uneconomical (addition amount of solidifying material necessary to satisfy the flow value of the treated soil and the target strength) Is inversely proportional). Therefore, the above-described correlation graph of FIG. 8 is used in determining a flow value that is a desirable flow value in terms of construction, quality, and economy.

  As described above, the correlation graph of FIG. 8 uses FIG. 7 in that the wet density ρt of the raw soil is used as a physical property value of the raw soil in addition to the table flow value that is an index of the improved processing depth and fluidity. Different from the ones.

  It is known that the mixing stirring resistance at the time of actual construction increases and decreases in direct proportion to the improved treatment depth and the wet density ρt of the raw soil. It is also known that the mixing stirrability is directly proportional to the mixing stir resistance, and the amount of solidifying material added necessary to satisfy the wet density ρt of the raw soil and the target strength is inversely proportional.

  Therefore, as in the previous case, in order to perform the construction so that the load resistivity Av value of the mixing and stirring head 3 satisfies the condition that it is 65% or less, the actual construction location (the ground subject to ground improvement) is the depth. 8 is selected from the graph of FIG. 8 according to the value of wet density ρt of the raw soil, and the fluidity of the treated soil immediately after the improvement treatment is changed for each improvement treatment depth so as to satisfy the flow value condition. It shall be constructed.

  By doing so, as in the previous case, the mixing and stirring head 3 performs the mixing and stirring process without difficulty and stably, so that there is little variation in quality and a large amount of work per unit time is ensured. As a result, not only can the cost be reduced, but also the workability, processing quality and economy can be satisfied.

  A measurement display panel 14 as a construction management device is detachably mounted on, for example, an instrument panel in the cabin of the backhoe 1 shown in FIGS. As shown in FIG. 9, the measurement display panel 14 includes first and second display units 16 and 17 and a setting device 18 that display various data necessary for construction in addition to the arithmetic processing unit 15. Various data necessary for construction are displayed on the first and second display units 16 and 17 in real time, and the data necessary for calculating the various data is set as necessary. It can be preset from the device 18 by manual operation. In the present embodiment, the value of the circumferential dimension K of the chain sprocket 5 for driving the drive chain 7 of the mixing and agitation head 3 described above is preset by the setting device 18 and taken into the arithmetic processing unit 15. Note that the measurement display board 14 has a time measuring function unit 19, for example, the time from pressing the start button (not shown) to the current time at an arbitrary timing, and the same time after pressing the start button. It is possible to measure the time until the outer stop button is pressed.

  Further, the backhoe 1 includes an angle sensor 20 for detecting the rotation angle of the arm 2, an angle sensor 22 for detecting the rotation angle of the boom 21, and the swirl turning direction (θ direction) of the mixing and stirring head 3. The angle sensors 23 for detecting the vertical degree of each are provided, and the detection output of each of the angle sensors 20, 22, 23 is the detection output (drive) of the rotation sensor 13 on the side of the mixing and stirring head 3 described above. The rotation number N (rpm) of the chain driving hydraulic motor 12 is input to the arithmetic processing unit 15 of the measurement display panel 14. In addition, as said angle sensor 20,22,23, the thing of the well-known structure called what is called a torque balance system is used.

  The arithmetic processing unit 15 of the measurement display panel 14 performs a predetermined calculation based on the detection output from the rotation sensor 13 and the angle sensors 20, 22, and 23 and the preset data, for example, as shown in FIG. As a result of the calculation, the chain speed and the accumulated travel distance and depth per division E are visually displayed on the first display unit 16 in real time as two forms of a numerical value and an accumulated cumulative waveform, respectively, as shown in FIG. Further, the vertical degree of the mixing and stirring head 3 is visually displayed on the second display unit 17 in real time.

  Here, since the chain speed is nothing but the circulating speed of the mixing stirring blades 8, 8,..., The rotational output N (rpm) of the rotation sensor 13 and the circumference K (m) of the chain sprocket 5 are calculated. Based on the previous equation (2).

  On the other hand, the cumulative travel distance per section E is not only the total travel distance of the drive chain 7 required for the ground improvement processing of the section E shown in FIG. , 8...) And the time required for the ground improvement process for the first division E. That is, it is assumed that the drive chain 7 is constantly moving around with the mixing agitating blades 8, 8... When the ground improvement in the first section E is performed, and the current (current) It is calculated by measuring the accumulated work time up to (time) and multiplying the accumulated work time (seconds) by the chain speed (m / sec). The accumulated work time can be reset at an arbitrary timing by operating a reset button (not shown).

  Further, as shown in FIG. 1, the depth H (m) is the depth of construction from the ground to the tip (lower end) of the mixing and stirring head 3, and is calculated by the following equation (3). This depth can also be reset at an arbitrary timing by operating a reset button (not shown).

H = D1-D2-α (3)
D1 = L1 × sin θ1
D2 = L2 × sin θ2
However,
D1: Vertical distance depending on the angle of the arm 2 D2: Vertical distance depending on the angle of the boom 21 L1: Distance (constant) from the upper end of the mixing and stirring head 3 to the connecting portion of the arm 2 and the boom 21
L2: Distance from the connecting portion of the arm 2 and the boom 21 to the vehicle fixing portion of the boom 21 (constant)
C: Offset amount by reset button operation Here, as described above, in the construction of one section E of width M × length L, as shown in FIG. It is assumed that the work is carried out while being overlapped by a predetermined amount each time after being divided into the narrow areas of (9).

  More specifically, as shown in FIG. 10, if the mixing and stirring head 3 having an effective processing width W is inserted into the first end portion of the first section E, the mixing and stirring head 3 is continuously moved in the width direction L in the direction of the arrow a1. As a ground improvement process, excavation and mixing agitation will be performed. Then, when the stroke end in the direction of the arrow a1 is reached, the mixing agitating head 3 is shifted by half the effective processing width W to the method of the arrow b1 in FIG. The same processing is performed by continuously moving in the direction of arrow a2 in FIG. When the mixing and stirring head 3 reaches the stroke end in the direction of the arrow a2, the mixing and stirring head 3 is shifted in the direction of the arrow b2 in the figure by half the effective processing width W, and thereafter, as shown in FIG. The same operation is repeated until the end of the first division E.

  In this case, while the operator confirms the second display portion 17 (see FIGS. 2 and 9) of the measurement display panel 14 installed in the cabin of the backhoe 1, the mixing and stirring head 3 is always in the vertical direction (the first display in FIG. 2). The orientation of the display unit 17 is controlled so as to be oriented in the direction of 0 degrees of the second display unit 17.

  That is, the movement of the mixing and stirring head 3 in the direction of the arrow a1 in FIGS. 10 to 13 is the forward movement, the movement of the mixing and stirring head 3 in the direction of the arrow a2 is the backward movement, and the movement of the mixing and stirring head 3 in the directions of the arrows b1 and b2. When the shift operation is performed, the forward and backward operations, the shift operation, and the shift operation are set as one cycle, and these operations are repeated a plurality of times to move the mixing and agitation head 3 along a movement path of a substantially rectangular wave in plan view. Construction shall be performed. Then, by shifting by half the effective processing width W of the mixing / stirring head 3 during the shift operation, at least two mixing / stirring processes are performed for any part of the section E. As a result, the processing quality can be improved and uniformized.

  Here, at the time of the first forward movement and the final forward movement or backward movement of the first section E, the moving speed of the mixing and stirring head 3 is set to about one half of the normal speed, and processing is performed at an extremely low speed. To do. By carrying out like this, the process equivalent to the case where it passes twice in spite of one pass of the mixing stirring head 3 can be performed. As a result, as shown in (B) of FIGS. 10 to 13, although there is a part e <b> 1 in which the mixed stirring process is performed three times in the first division E after the treatment, the entire area of the first division E On average, at least two mixing and stirring processes were performed.

  Here, instead of performing the mixing and stirring process under the movement locus of the substantially rectangular wave-shaped mixing and stirring head 3 in a plan view as described above, a substantially zigzag in a plan view as shown in FIGS. The same effect can be obtained even if the mixing and stirring process is performed under the movement trajectory.

  As shown in FIG. 18, when the improvement processing depth t is larger than the effective length t1 of the mixing and stirring head 3, the upper end of the mixing and stirring head 3, more specifically, the chain sprocket 5 for driving the chain. It is assumed that the construction is carried out while positively moving the entire mixing and stirring head 3 up and down until the radial dimension t2 of about 2 mm comes to the surface. By carrying out like this, even if the effective length t1 of the mixing stirring head 3 is smaller than the improvement processing depth t, a more uniform construction can be performed in the depth direction.

  19 to 23 show other construction examples. In this construction example, the construction is performed so that the moving trajectory of the mixing and stirring head 3 is substantially N-shaped in a plan view.

As shown in FIG. 19, in the construction of the first section E, the four poles 29, 29. To mix and stir. By performing the construction at a speed that is 1/2 of the construction basic speed, the same effect as that obtained when the mixing and stirring treatment is substantially performed twice for the construction area e11 in the first lane can be obtained.
Next, as shown in FIG. 20, similarly, the poles 29, 29,... Are marked, and the second lane region e12 is slanted at the basic construction speed so that the half overlaps with the first lane construction region e11. Construct about. As a result, a total of three mixing and stirring processes are performed in the overlap region e13.

  Subsequently, as shown in FIG. 21, the construction is performed straight at the construction basic speed for the area e14 in the third lane so that the half of the construction area e12 in the second lane overlaps. As a result, a total of two mixing and stirring processes are performed in the overlap region e15. Thereafter, the same construction as in FIGS. 20 and 21 is sequentially repeated.

  Here, when constructing the area e20, which is the lane at the end of the work for one day, construction is performed at a speed that is ½ of the basic construction speed as shown in FIG. By doing so, in the overlap region e19 with the adjacent lane where the construction was completed immediately before that, the mixing and stirring treatment was substantially performed three times in total.

  On the other hand, for the construction of the area e21 in the first lane on the next day, adjacent to the area e20 of the last construction lane on the previous day where partial solidification is in progress, the construction basic speed is 1 as in the case of FIG. Construction is performed at a speed of / 2, and thereafter, construction exactly the same as in FIGS. 20 to 23 is sequentially repeated.

  In this construction method as well, although there is a part where the mixed stirring process is performed three times in the first section E after the treatment, at least two mixed stirring processes are averaged over the entire area of the first section E. It has been given.

  24 to 26 show a second embodiment of the present invention.

  In the first embodiment, the rotation speed 13 of the chain driving hydraulic motor 12 is detected by the rotation sensor 13 provided in the mixing and stirring head 3, and the rotation of the drive chain 7 is determined based on the detected output. In contrast to calculating the speed C1 and managing the construction at the rotational speed C1 of the drive chain 7, in the second embodiment, mixing and stirring is performed from the hydraulic power unit 30 mounted on the backhoe 1. The construction management is performed with the discharge pressure of the hydraulic oil to the head 3. The depth management is the same as that in the first embodiment.

  As shown in FIG. 25 in addition to FIG. 24, the hydraulic motor 12 of the mixing and stirring head 3 is driven by the supply of hydraulic oil from the hydraulic power unit 30 mounted on the backhoe 1. A pressure sensor 31 is attached to the hydraulic pump, which is the main element, and the discharge pressure of hydraulic oil supplied to the hydraulic motor 12 of the mixing and stirring head 3 is detected by the pressure sensor 31.

  Since the hydraulic pump of the hydraulic power unit 30 is generally a variable displacement pump, the PQ characteristic that is the correlation between the discharge pressure P (MPa) and the flow rate Q (liters / min) is shown in FIG. Like 25. Since the amount of oil discharged from the variable displacement hydraulic pump changes according to the load, the mixing and agitation head 3 is based on the discharge pressure P shown in FIG. It is intended to calculate the load resistivity.

  Note that the hydraulic oil discharge pressure P of the hydraulic power unit 30 is visually displayed in real time as two forms of a numerical value and a cumulative integrated waveform on the second display unit 16 of the measurement display panel 14, as shown in FIG.

  And the load of the trencher type mixing and agitation head 3 that controls the in-situ excavation and the mixing and agitation process as described above is always 65% or less regardless of the depth of the improvement process depth to be constructed. Furthermore, the improvement process shall be performed by changing the fluidity of the treated soil immediately after the improvement process according to the improvement process depth. More specifically, the load resistivity of the mixing and stirring head 3 at the time of mixing and stirring is Ap, the hydraulic oil discharge pressure of the hydraulic power unit 30 at the time of no load is Pa (MPa), and the hydraulic oil discharge of the hydraulic power unit 30 at the time of mixing and stirring. When the pressure is Pd (MPa), the load resistivity Ap of the mixing and stirring head 3 calculated from the following equation (4) is 65% or less so that the value immediately after the improvement process depends on the improvement process depth. It shall be improved by changing the fluidity of the treated soil.

Ap = {1- (Pa / Pd)} × 100 (%) (4)
However,
Ap: Load resistivity of the mixing agitation head at the time of mixing agitation Pa: Hydraulic oil discharge pressure of the hydraulic power unit at the time of no load Pd: Hydraulic oil discharge pressure of the hydraulic power unit at the time of mixing agitation In this case, the hydraulic power unit 30 at no load As shown in FIG. 26A, the hydraulic oil discharge pressure Pa (MPa) is rotated as a so-called idle operation with the mixing and stirring head 3 pulled up to the ground, and the hydraulic oil discharge pressure Pa ( MPa) is measured and recorded in advance.

  Further, the hydraulic oil discharge pressure Pd (MPa) of the hydraulic power unit 30 at the time of mixing and stirring fluctuates due to the mixing and stirring resistance unlike when no load is applied, and therefore, for example, as shown in FIG. A trial operation for the section E is performed, and the hydraulic oil discharge pressure Pd (MPa) of the hydraulic power unit 30 at the time of actual mixing and stirring is stored or recorded in real time, and an average value thereof is obtained in advance.

  In order to perform the construction so that the value of the load resistivity Ap of the mixing and stirring head 3 calculated by the above formula (4) satisfies the condition of 65% or less, the hydraulic oil of the hydraulic power unit 30 at the time of actual mixing and stirring is used. Since the construction is such that the discharge pressure Pd does not exceed a specific pressure value, the hydraulic oil discharge pressure Pd of the hydraulic power unit 30 at the time of actual mixing and agitation is set, for example, in the cabin of the backhoe 1 as described later. The above-mentioned specific pressure value is presented to the operator at the same time.

  More specifically, for example, as shown in FIG. 26A, when the so-called idling operation is performed and the mixing stirring blades 8, 8... It is assumed that the hydraulic oil discharge pressure Pa is, for example, 10 MPa.

  When this is applied to the above equation (4), the hydraulic oil discharge pressure Pd at which the load resistivity Ap is 65% is 28.6 MPa. Therefore, a pressure of 28.6 MPa is presented to the operator as a control limit value, and the hydraulic oil discharge pressure of the hydraulic power unit 30 that will be displayed in real time in the cabin during actual mixing and stirring as described above. Instruct to perform construction so that Pd does not exceed the above control limit value. As a result, the operator can visually confirm the hydraulic oil discharge pressure Pd of the hydraulic power unit 30 to be visually displayed in real time in the cabin, and perform the construction so that the value does not exceed the control limit value, The required load resistivity Ap of the mixing and stirring head 3 can satisfy the condition of 65% or less.

  For example, as shown in FIG. 26 in addition to FIG. 25, the hydraulic oil discharge pressure Pa of the hydraulic power unit 30 at no load was 10 MPa, and the hydraulic oil discharge pressure Pd of the hydraulic power unit 30 at the time of actual mixing and stirring was 23.5 MPa. In this case, when the above equation (4) is applied, the load resistivity Ap of the mixing and stirring head 3 is represented by the following equation (5). The above numerical value of 23.5 MPa is nothing but the result of the operator performing the construction so as not to exceed the control limit value (= 28.6 MPa) presented in advance.

Ap = {1- (10 / 23.5)} × 100 (%) = 57.4% (5)
Thus, the numerical value of the load resistivity Ap = 57.4% sufficiently satisfies the requirement that the value Ap is 65% or less.

  Here, as the first display unit 16 of the measurement display board 14 which is a construction management device, the first embodiment substantially shown in FIG. 1 and the second embodiment shown in FIG. As shown in FIG. 27, it is also possible to visually display the chain speed, the one-division cumulative movement distance, the depth, and the hydraulic oil discharge pressure in two forms of a numerical value and a cumulative cumulative waveform, as shown in FIG. .

BRIEF DESCRIPTION OF THE DRAWINGS Whole explanatory drawing which shows the outline of the construction system for ground improvement as preferable embodiment of this invention. The whole explanatory view showing the outline of the construction system for ground improvement similarly. Plane explanatory drawing of FIGS. It is an enlarged view of the mixing and stirring head shown in FIGS. 1 and 2, (A) is a front explanatory view, and (B) is a side explanatory view. (A) is explanatory drawing which expand | deployed the drive chain shown in FIG. 4, (B) is explanatory drawing only with a mixing stirring blade. Explanatory drawing which shows the construction procedure in the construction system shown to FIG. The graph which shows the correlation with the improvement processing depth and the flow value of a table test. The graph which shows the correlation with the improvement processing depth, the flow value of a table test, and the wet density of a raw soil. The functional block circuit diagram of the measurement display board shown to FIG. Explanatory drawing which shows the more detailed construction procedure in the construction system shown to FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing which shows another construction procedure in the construction system shown to FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing which shows another construction procedure in the construction system shown to FIG. Explanatory drawing which shows the further another construction procedure in the construction system shown to FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Explanatory drawing of the construction procedure following FIG. Whole explanatory drawing which shows the outline of the construction system for the ground improvement as the 2nd Embodiment of this invention. The PQ diagram which shows the correlation with the pump pressure P and the flow volume Q in the hydraulic power unit of the backhoe shown in FIG. Explanatory drawing which shows the construction procedure in the construction system shown in FIG. Explanatory drawing which shows the modification of the display part of the construction management apparatus shown in FIG. The graph which shows the relationship between target intensity | strength and solidification material addition amount.

Explanation of symbols

1 ... Backhoe as a construction machine (base machine or mother machine)
2 ... Arm 3 ... Mixing and stirring head (processing machine)
7 ... Drive chain 8 ... Mixing stirring blade 13 ... Rotation sensor (detection means)
DESCRIPTION OF SYMBOLS 14 ... Measurement display board 15 ... Operation processing part 16 ... 1st display part (display means)
17 ... 2nd display part (display means)
20. Angle sensor (detection means)
22 ... Angle sensor (detection means)
23. Angle sensor (detection means)
30 ... Hydraulic power unit 31 ... Pressure sensor (detection means)

Claims (10)

In the ground improvement method to increase the strength of the in-situ soil by mixing and stirring with the solidified material while excavating the in-situ soil with a depth of 15 m or less,
At the tip of the arm of the construction machine that functions as a mother machine, a mixing agitation head equipped with a mixing agitation blade that moves around in the vertical direction is installed.
A ground improvement method characterized by performing an improvement process so as to satisfy the following conditions (a) and (b).
(A) As the relationship between the degree of fluidity of the treated soil immediately after the improvement treatment and the improvement treatment depth, which are considered to be favorable at least in terms of economy and workability, the fluidity of the treated soil increases as the improvement treatment depth increases. Thus, the improved processing depth-fluidity characteristic is determined in advance, and based on this improved processing depth-fluidity characteristic, a target fluidity characteristic value is obtained when the improved processing depth of the processing target area is designated, and processing is performed. The fluidity of the treated soil immediately after the improvement treatment in the target area should be the above fluidity characteristic value.
(B) The average rotational speed of the mixing and stirring blades during actual mixing and stirring should not be less than one half of the rotational speed of the mixing and stirring blades when there is no load. Instead of the above improved processing depth-fluidity characteristics,
As the relationship between the degree of fluidity of the treated soil immediately after the improvement treatment and the improvement treatment depth, which are considered to be favorable at least in terms of economy and workability, the fluidity of the treated soil increases as the improvement treatment depth increases and the raw soil In order to increase the fluidity of the treated soil as the wet density of the soil increases, the improved treatment depth-wet density of the raw soil-fluidity characteristics are determined in advance.
Based on this improved treatment depth-wet density of the soil-fluidity characteristics, obtain the target fluidity characteristic value when the improved treatment depth of the treatment target area and the wet density of the raw soil are specified,
The ground improvement method according to claim 1, wherein the improvement treatment is performed so that the fluidity of the treated soil immediately after the improvement treatment in the treatment target region becomes the fluidity characteristic value.   The ground improvement method according to claim 1 or 2, wherein the improvement treatment is performed while measuring the circumferential speed of the mixing stirring blade.   The ground improvement method according to claim 1 or 2, wherein the improvement treatment is performed while measuring the improvement treatment depth by the mixing stirring blade.   The ground improvement construction method according to any one of claims 1 to 4, wherein the improvement process is performed by continuously moving the mixing and stirring head under a movement path having a substantially rectangular wave shape in plan view. The movement of the mixing and agitation head, which is a substantially rectangular wave-shaped movement trajectory, repeats a plurality of cycles, with the forward movement operation and the backward movement operation in the arm length direction in a plan view and the shift operation between both operation positions as one cycle. Shall be
6. The ground improvement method according to claim 5, wherein the shifting operation of the mixing and stirring head is performed within a processing width dimension of the mixing and stirring head in a plan view.   6. The improvement process is performed by continuously moving the mixing and stirring head under a substantially zigzag-like movement locus in a plan view instead of a substantially rectangular wave-like movement locus in a plan view. Or the ground improvement construction method of 6.   The improvement processing is performed by continuously moving the mixing and stirring head under a substantially N-shaped movement locus in a plan view instead of a substantially rectangular wave-like movement locus in a plan view. The ground improvement construction method according to 5 or 6. A ground improvement machine for use in the ground improvement method according to any one of claims 1 to 8,
A ground improvement machine characterized by comprising means for measuring at least one of the improvement processing depth by the mixing stirring head, the verticality of the mixing stirring head, and the circumferential speed of the mixing stirring blade.   The ground improvement machine according to claim 9, further comprising means for measuring an improvement treatment depth by the mixing agitation head, a vertical degree of the mixing agitation head, and a circumferential speed of the mixing agitation blade.

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