JP2012246658A - Construction management system in ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction management system in a ground improvement method, which enables speedy calculating an estimated amount of excavated soil with high reliability.SOLUTION: An inventive construction management system is applied to a ground improvement method in which a screw rod equipped with an agitation blade at its tip is penetrated into the ground, a ground improvement material is injected into the ground, the screw rod is pulled out while the ground improvement material and sediment are agitated/mixed together by rotation of the agitation blade, and the sediment equivalent to the amount of the injected ground improvement material is removed. In the construction management system, a depth, the number of revolutions, penetration speed, and pulling-out speed of the screw rod, and an injection amount of the ground improvement material are detected and monitored. Then, a ratio of the injection amount of the ground improvement material slurry to the ground to be improved is regarded as a ground improvement material mixing ratio, an earth removal factor is set on the basis of a predetermined ground improvement material mixing ratio from a relationship between a preliminarily obtained ground improvement material mixing ratio and earth removal factor, an estimated amount of soil excavated by the screw rod is calculated on the basis of the set earth removal factor and the number of revolutions, and the estimated amount of excavated soil is monitored as a management item.

Description

  The present invention relates to a construction management system applied to a ground improvement method that belongs to the category of deep mixing treatment method.

  The deep mixing treatment method is based on the fact that a large number of improved piles are formed in the original ground by injecting a ground improvement material such as cement slurry into the original ground and agitating and mixing with the earth and sand, thereby increasing the strength of the original ground. This is a ground improvement method.

  FIG. 6 is a schematic diagram of the processing machine 1 applied to such a deep mixing processing method and a construction management system applied thereto. The processing machine 1 vertically supports a screw rod 3 having a stirring blade 2 at the tip by a base machine 4 and rotates the screw rod 3 by a driving device 5 to penetrate to the deepest part in the range to be improved. Pulling out the screw rod 3 while injecting cement slurry as a ground improvement material into the ground from the discharge port provided at the tip of the rod 3 and stirring and mixing the injected cement slurry and earth and sand with the stirring blade 2 It is configured to form an improved pile.

  Moreover, the construction management system in the case of forming an improved pile by the processing machine 1 includes a slurry flow meter 6, a shaft tachometer 7 of the screw rod 3, a current detector 8 of the drive device 5, a depth meter 9 of the screw rod 3, and An elevation speed meter 10 is provided, and detection values from these sensors are input to the management device 11 so as to monitor the amount of cement slurry injected, the number of rotations of the screw rod 3, the depth of penetration, the penetration speed, and the withdrawal speed as management items. It is configured. Reference numeral 12 denotes an operation monitor installed in the base machine 4, and 13 denotes a data storage personal computer.

  Here, in the conventional general deep mixing method as described above, it is inevitable that the volume of the original ground increases because a large amount of ground improvement material (cement slurry) is injected into the original ground. As a result, there were concerns that the ground would swell and adversely affect the surrounding ground.

  Therefore, as a measure to prevent adverse effects on the surrounding ground in the above-mentioned deep mixing treatment method, soil equivalent to the injection amount (discharge amount) of ground improvement material (cement slurry) is discharged from the original ground. The present applicant has also proposed a soil-excluded deep mixing process method and its construction management system for avoiding volume expansion of the original ground (see, for example, Patent Document 1). An important point in this ground improvement method is whether the amount of ground improvement material injected and the amount of soil discharged are balanced, and it is the point of construction management to grasp both amounts. However, the amount of ground improvement material injected can be measured with a flow meter, but it is difficult to grasp the actual amount of soil discharged during construction. Therefore, in Patent Document 1, in an actual measurement test, an actual measured amount of soil V1 and a value of (screw cross-sectional area S) × (screw pitch P) × (shaft rotation speed N) are obtained, and K = V1 / ( The soil removal coefficient K was obtained based on (S × P × N). Specifically, several points of the value of V1 with respect to the value of (S × P × N) are dropped on the orthogonal coordinates having (S × P × N) as the horizontal axis and V1 as the vertical axis. From these points, a first order approximate expression is obtained. The slope in this linear approximation is K. Then, from the set soil discharge coefficient K and the S, P, N values that can be actually measured in the subsequent work, the estimated amount V of soil discharged in the work is calculated according to the calculation formula V = K × S × P × N. I was looking for.

Japanese Patent No. 3583307

  However, this actual measurement test needs to be performed at least three times for each construction site and every soil, which is time-consuming and time-consuming. In addition, a considerable number of data is required to ensure reliability, but it has been difficult to obtain a considerable number of data in an actual test.

  Then, this invention is made | formed in view of the said situation, and provides the construction management system in the ground improvement construction method which can calculate the estimated amount of soil removal with high reliability rapidly.

  In order to solve the above-mentioned problem, the invention described in claim 1 is to insert a screw rod having a stirring blade at a tip portion into the ground and inject a ground improvement material into the ground through the screw rod. The ground improvement is performed by pulling out the screw rod while stirring and mixing the ground improvement material and the earth and sand by the rotation of the stirring blade, and discharging soil equivalent to the injection amount of the ground improvement material from the ground by the screw rod. In the construction management system, which is applied when carrying out a construction method and detects and monitors the depth, rotation speed, penetration speed and drawing speed of the screw rod, and the injection amount of the ground improvement material, the ground improvement material for the improved ground Let the ratio of slurry injection amount be the ground improvement material mixing rate, and determine the predetermined ground improvement material mixing rate from the relationship between the ground improvement material mixing rate and the soil removal coefficient determined in advance. A soil removal coefficient is set based on the estimated soil removal amount by the screw rod based on the set soil removal coefficient and the rotation speed, and the estimated soil removal amount is monitored as a management item. It is characterized by that.

  According to the invention described in claim 1, it is possible to set the soil removal coefficient based on the soil improvement material mixing rate, and to calculate the estimated soil removal amount based on the soil removal coefficient, By setting it as a management item, it is possible to quickly calculate an estimated amount of soil removal with high reliability. As a result, there is an effect that it is possible to contribute to the construction period and cost while suppressing the displacement of the original ground.

  The invention described in claim 2 is characterized in that the estimated amount of soil removal is compared with the injection amount of the ground improvement material to determine whether construction is good or bad.

  According to the invention described in claim 2, the construction reliability can be sufficiently ensured by determining the construction quality by comparing the estimated amount of soil removal with the amount of the ground improvement material injected, and it is necessary to carry out correction construction. Sex becomes clear.

  According to the construction management system in the ground improvement method of the present invention, it is possible to set the soil removal coefficient based on the soil improvement material mixing rate, and to calculate the estimated soil discharge amount based on the soil removal coefficient. By using the soil volume as a management item, it is possible to quickly calculate the estimated soil discharge volume with high reliability. As a result, there is an effect that it is possible to contribute to the construction period and cost while suppressing the displacement of the original ground.

It is a figure which shows the outline | summary of the construction management system which is embodiment of this invention. It is a figure which shows the determination method of the soil discharge coefficient (in the case of cohesive soil) used in the system. It is a figure which shows an example of the management data in the same system. It is a figure which shows the other example of the management data in the same system. It is a figure which shows the determination method of the soil discharge coefficient (in the case of sandy soil) used in the system. It is a figure which shows the outline | summary of the processing machine and construction management system in the conventional deep mixing processing method.

  Hereinafter, a specific embodiment of the construction management system of the present invention will be described with reference to FIG. The ground improvement method to which the construction management system of the present embodiment is applied is a soil-discharging type deep mixing treatment method using the improvement machine 1 shown in FIG. That is, in the improvement machine 1 of FIG. 6, while rotating the screw rod 3 provided with the stirring blade 2 into the ground, and without injecting cement slurry (ground improvement material slurry) composed of water and cement to a predetermined improvement depth. Then, the screw rod 3 is rotated to improve the bottoming of the deepest portion, and the screw rod 3 is rotated to rotate the slurry discharge port at the tip of the screw rod 3 (in FIG. 6, the slurry discharge port is illustrated). 6, the slurry discharge port is provided in the vicinity of the lower end position of the screw rod 3 and the uppermost stirring blade 2 among the plural stages of the stirring blades 2. When the bottoming is improved, the slurry at the lower end of the screw rod is provided. The ground improvement material slurry is injected from the discharge port. The ground improvement material slurry is injected when the screw rod 3 is pulled out. In the ground improvement method in which the ground improvement material slurry is pulled out while the ground is stirred and mixed with the stirring blades 2 while the ground improvement material slurry is being injected from the nearby slurry discharge port. By doing so, it is a method of reducing the ground displacement accompanying the ground improvement material slurry injection. The construction management system according to the present embodiment is based on the conventional construction management system shown in FIG. 6, but adds the “soil discharge amount” that is different from the calculation method to the management items and uses the improved machine 1. By monitoring the amount of soil discharged and maintaining it properly, it is configured to prevent displacement of the original ground (swelling and adverse effects on the surrounding ground). Furthermore, in the construction management system of the present embodiment, the “blade cutting frequency” is also a management item in the same manner as in the past in order to quantitatively grasp the stirring and mixing state of cement slurry and earth and sand and manage them appropriately.

  That is, the construction management system of the present embodiment sets “material”, “combination”, and “mixing (number of blade cuttings)” as control items for quality control, as shown in FIG. “Positioning position”, “Placement depth”, and “Bottom” are set as management items for management, and “Soil discharge amount” is set as a management item for displacement management of the ground.

  Among the management items common to the past, “material” is used to manage the state of cement slurry (cement amount and water amount) as a ground improvement material, and “mixing” is the slurry injection amount detected by the slurry flow meter 6 and the elevation The “placement position” is used to control whether the injection amount per unit depth is appropriate based on the lifting speed of the screw rod 3 detected by the speedometer 10. What is managed, “placement depth” is the one that detects the position of the screw rod 3 by the depth meter 9 and manages it, and “bottom” is the operating state of the drive device 5 detected by the ammeter 8 and the lifting speed. Whether or not the tip of the screw rod 3 has reached the deepest part of the improvement target range is managed based on the penetration speed detected by the total 10.

  Among the management items added in the present embodiment, the “soil removal amount” is calculated by calculating the estimated soil removal amount based on the rotational speed of the screw rod 3 detected by the shaft tachometer 7, the screw shape and the soil removal coefficient. , It is managed so as to be equivalent to the slurry injection amount.

In the present embodiment, the estimated amount of soil removal is performed as follows. The estimated soil removal amount V is a function of the screw cross-sectional area S, the screw pitch P, and the rotation speed N, and is expressed as follows, with the proportionality constant as the soil removal coefficient K.
V = K · S · P · N (1)
V: Estimated amount of soil removed (m ³ )
K: soil removal coefficient S: screw cross-sectional area (m ² )
P: Screw pitch (m)
N: Shaft rotation speed (times)
In the above equation (1), the screw cross-sectional area S and screw pitch P are inherent constants of the improved machine 1, so once the value of the soil removal coefficient K is determined, the shaft rotational speed N from penetration to withdrawal is measured. It is possible to calculate the estimated soil discharge amount V only by doing.

Here, the inventors of the present application think that there is a correlation between the soil removal coefficient K and the ground improvement material mixing rate x, and based on a large number of construction results, the soil removal coefficient K and the ground improvement The correlation with the material mixing rate x was examined. As a result, a correlation between the ground improvement material mixing rate x and the soil discharge coefficient K as shown in FIG. 2 was obtained. FIG. 2 shows the number of data n = 99, from which the following equation (straight line in FIG. 2) is obtained.
K = 0.5116x + 0.0066 (2)
x: Ground improvement material mixing rate (%)
Note that the above equation (2) is an equation when the ground is cohesive soil, and it can be said that there is a strong correlation since the correlation coefficient r = 0.81. A similar correlation equation can be obtained in advance for each soil condition.

Further, the ground improvement material mixing rate x is a volume ratio of the injection amount of the ground improvement material slurry to the improved ground, and is determined by how much the strength of the improved ground is made. The addition amount (kg) of the ground improvement material added to the unit improvement ground (1 m ³ ) is determined in advance. For example, the addition amount per 1 m ^{3 of the} improvement ground is about 100 kg. The ground improvement material is injected as a ground improvement material slurry (cement slurry) in which water is added to cement. The addition ratio W / C of water (W) to cement (C) is also taken into account in consideration of workability. Set it. In general, W / C is set to about 100%. In this case, the improvement material slurry corresponding to the added amount of 100 kg is about 133 liters (specific gravity of cement is 3). When 133 liters of the improved material slurry is injected and mixed in 1 m ^{3 of the} improved ground, the ground improved material mixing ratio x = 0.133 (13.3%). Thus, the ground improvement material mixing rate x is determined in advance. Then, x = 0.133 is substituted into the above equation (2) to calculate the soil removal coefficient K = 0.075.

  As described above, the soil removal coefficient K is calculated and set from the above equation (2) based on the predetermined ground improvement material mixing rate x. Alternatively, the soil removal coefficient K corresponding to the ground improvement material mixing rate x is set on the drawing from the straight line of the above equation (2) based on the orthogonal coordinates of the soil removal coefficient K and the ground improvement material mixing rate x. Then, if the set soil removal coefficient K, the screw cross-sectional area S, and the screw pitch P are input to the management device 11, the rotational speed N detected by the shaft tachometer 7 is only input to the management device 11. The estimated soil discharge amount V is calculated and calculated by the above equation (1). It is preferable that the output of the shaft rotational speed N from the shaft tachometer 7 is automatically input to the management device 11. By doing so, the estimated soil removal amount V is immediately calculated and calculated after the screw rod 3 is pulled out with the soil removal coefficient K, screw cross-sectional area S, and screw pitch P inputted in advance. And in the construction management system of this embodiment, every time one improved pile is constructed, the estimated amount of soil removal V is calculated, and the construction is compared with the amount of slurry injected detected by the slurry flow meter 6. The quality is judged. Note that, if the rotational speed N is adjusted, the estimated soil removal amount V can be increased or decreased, and if necessary, the estimated soil removal amount V can also be controlled momentarily.

  In addition, the “number of blade cuttings” which is another management item in the present embodiment is a value indicating the number of times blade cutting is performed by each stirring blade 2 when the screw rod 3 is pulled out by a unit length. It is represented by

T = M × n / v (3)
T: Number of blade cuts (times / m)
M: Total number of stirring blades (sheets)
n: Number of rotations (times / minute)
v: Pulling speed (m / min)

  Since the total number M of the stirring blades 2 in the above equation (3) is a constant unique to the improved machine, the number of blade cuttings is determined by the rotational speed n detected by the shaft tachometer 7 and the drawing speed v detected by the speedometer 9. T can be obtained based on the above equation, and the management device 11 automatically calculates and calculates the blade cutting frequency T when the total number M of stirring blades is input, and the blade cutting frequency is within a predetermined management range value. You can see if there is.

  Each of the above management items is input to the management device (computer) 11 for evaluation, that is, whether the construction is good or bad, and based on the judgment, correction construction is performed as necessary. Then, the construction data is stored in the personal computer 13, and appropriate management data, for example, a “construction result table” as shown in FIG. 3 and a “pile placing daily report” as shown in FIG. 4 are printed out as necessary.

  According to the construction management system of this embodiment described above, in addition to being able to perform the same quality control and finished shape management as before when performing ground improvement by the soil removal type deep mixing treatment method, It is possible to quickly estimate the amount of soil that is discharged near the earth, which enables high-precision construction management and contributes to the improvement of construction efficiency.

  In addition, in the construction management system of the present embodiment, the degree of stirring and mixing of cement slurry and earth and sand can be quantitatively grasped by managing the number of blade cuttings, so that an excellent ground improvement effect can be obtained. .

  In addition, the calculation of the soil removal coefficient K is automatically performed if a plurality of correlation equations for each soil type are programmed in the construction management system, and the soil improvement material mixing rate x is selected by selecting the soil type in the construction management system. It is possible to calculate and set the soil discharge coefficient K by manual calculation using a separate computer, and input the calculated value of the soil discharge coefficient K to the construction management system. May be. The subsequent method of calculating the estimated soil discharge amount V from the soil discharge coefficient K is as described above. The “construction result table” in FIG. 3 is an output example of a system that automatically calculates the estimated soil discharge amount V when the ground improvement material mixing rate x is input.

  The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific structure and configuration described in the embodiment are merely examples, and can be changed as appropriate.

For example, in the present embodiment, the calculation formula for the soil removal coefficient when the ground is a viscous soil is shown. it can. FIG. 5 is a graph showing the correlation between the soil improvement material mixing rate x and the soil discharge coefficient K in the case of sandy soil. FIG. 5 shows the number of data n = 16, from which the following equation (straight line in FIG. 5) is obtained.
K = 0.4935x−0.0252 (4)
Note that since the above equation (4) has a correlation coefficient r = 0.858, it can be said that there is a strong correlation. In this way, the estimated soil removal rate can be calculated quickly by obtaining a formula for calculating the soil removal factor in advance for each soil condition or by creating a setting chart. However, the correlation equation described in the present embodiment can be changed by taking in more data from the implementation. In addition, the soil discharge coefficient calculation method of the present embodiment can also be applied to the ground improvement method in which the ground improvement material slurry is injected into the ground and stirred when the screw rod penetrates.

  DESCRIPTION OF SYMBOLS 1 ... Improvement machine 2 ... Stirring blade 3 ... Screw rod 6 ... Slurry flow meter 7 ... Shaft tachometer 8 ... Current detector 9 ... Depth meter 10 ... Speedometer 11 ... Management device

In order to solve the above-mentioned problem, the invention described in claim 1 is to insert a screw rod having a stirring blade at a tip portion into the ground and inject a ground improvement material into the ground through the screw rod. The ground improvement is performed by pulling out the screw rod while stirring and mixing the ground improvement material and the earth and sand by the rotation of the stirring blade, and discharging soil equivalent to the injection amount of the ground improvement material from the ground by the screw rod. In the construction management system, which is applied when carrying out a construction method and detects and monitors the depth, rotation speed, penetration speed and drawing speed of the screw rod, and the injection amount of the ground improvement material, the ground improvement material for the improved ground the ratio of slurry injection volume and soil improvement material mixing rate, the relationship between the pre-ground conditions by on the obtained soil improvement material mixing rate and earth removal coefficient, a predetermined ground Set the soil removal coefficient based on the good material mixing rate, calculate the estimated soil removal amount by the screw rod based on the set soil removal coefficient and the rotation speed, and monitor the estimated soil removal amount as a management item It is characterized by having a configuration to do.

Claims (2)

A screw rod having a stirring blade at the tip is inserted into the ground, a ground improvement material is injected into the ground through the screw rod, and the ground improvement material and earth and sand are stirred and mixed by rotation of the stirring blade. While pulling out the screw rod while applying the ground improvement method of discharging soil equivalent to the injection amount of the ground improvement material from the ground by the screw rod, the depth of the screw rod, the rotation speed, In the construction management system for detecting and monitoring the penetration speed and the drawing speed, and the injection amount of the ground improvement material,
The ratio of the ground improvement material slurry injection amount to the improved ground is the ground improvement material mixing rate,
From the relationship between the ground improvement material mixing rate and the soil removal coefficient determined in advance, set the soil removal coefficient based on the predetermined ground improvement material mixing rate,
In the ground improvement method characterized in that the estimated soil removal amount by the screw rod is calculated based on the set soil removal coefficient and the rotation speed, and the estimated soil removal amount is monitored as a management item. Construction management system.   The construction management system in the ground improvement method according to claim 1, wherein the estimated soil discharge amount is compared with the injection amount of the ground improvement material to determine whether the construction is good or bad.

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