JP6969110B2 - Ground judgment method and drilling device - Google Patents

Description

The present invention relates to a ground determination method and a drilling device for determining whether or not the ground has been reliably rooted during ground reinforcement work.

In the ground reinforcement work, a grout material such as cement milk or cement mortar is pressure-injected after performing drilling work by a tip-driven drilling system until it reaches the support layer in the ground (for example, Patent Document). 1 and Patent Document 2). Generally, in the above-mentioned drilling work, it is determined whether or not the soil-removed slime component discharged at the time of drilling and the existing columnar chart have reached (rooted) the support layer in the ground. doing.

Japanese Patent No. 2592079 Japanese Patent No. 5695307

In recent years, stricter rooting management in ground reinforcement work has been required. Therefore, in addition to the state of soil drainage slime used in the past and the existing columnar chart, various data obtained at the time of drilling are not used as a qualitative ground determination method with reference to the speed at the time of drilling (drilling speed). It is necessary to develop a new quantitative ground determination method using (numerical value).

The present invention is to newly provide a quantitative ground determination method and a drilling device using various data obtained at the time of drilling.

In order to solve the above-mentioned problems, the ground determination method of the present invention is a ground determination method for drilling holes and placing steel pipes using a double pipe type down-the-hole hammer, and uses a drilling bit. For the drilling in the first drilling step and the first drilling step of performing the drilling while keeping the feeding force at the time of drilling and the rotation speed of the drilling bit constant. The acquisition process for acquiring the number of rotations of the bit, the rotational torque applied to the drilling bit, the drilling speed in the drilling bit, and the depth of the drilling bit, the coefficient for ground determination is α, and the drilling The bottom area of the drilling bit is A, the rotation speed of the drilling bit obtained by the acquisition step is N, the rotational torque applied to the drilling bit is T, and the drilling speed of the drilling bit is B. Based on the step of calculating the rotational energy represented by the following equation (1) and the fluctuation of the rotational energy, it is determined whether or not the drilling and the placement of the steel pipe have reached the support layer in the ground. It is characterized by having an evaluation process to be performed.
Rotational energy = α ・ (2π ・ N ・ T) / (A ・ B) ・ ・ ・ (1)

Further, at least the index among the rotation speed of the drilling bit, the rotational torque applied to the drilling bit, the drilling speed in the drilling bit, the depth of the drilling bit, and the index is displayed. It is characterized by having a display process.

Further, the first drilling step includes an estimation step of estimating the depth of the support layer in the ground and a second drilling step of drilling holes to a depth near the support layer in the ground. , The second drilling step is subsequently carried out.

The drilling is characterized by being carried out using a small diameter steel pipe pile method.

Further, the drilling device of the present invention is a drilling device for drilling holes and driving steel pipes until it reaches the support layer in the ground using a double pipe type down-the-hole hammer . The acquisition unit that acquires the number of rotations of the bit, the rotational torque applied to the drilling bit, the drilling speed in the drilling bit, and the depth of the drilling bit, the coefficient for determining the ground is α, and the drilling Let A be the bottom area of the drilling bit, N be the rotation speed of the drilling bit obtained by the acquisition unit, T be the rotational torque applied to the drilling bit, and B be the drilling speed of the drilling bit. , An evaluation unit that calculates the rotational energy represented by the following equation (2), and an evaluation that determines whether or not the drilling and the placement of the steel pipe have reached the support layer based on the fluctuation of the rotational energy. It is characterized by having a part and.
Rotational energy = α ・ (2π ・ N ・ T) / (A ・ B) ・ ・ ・ (2)

According to the present invention, it is possible to newly provide a quantitative ground determination method using various data obtained at the time of drilling.

It is a side view which shows an example of the drilling apparatus used in the small-diameter steel pipe pile construction method. It is a perspective view which shows the shape of the simulated ground. It is a graph which shows the fluctuation of the drilling speed, the feeding force, the rotational torque, the rotational speed, and the rotational energy obtained in the drilling test when the soft rock ground is used as the simulated ground. It is a graph which shows the fluctuation of the drilling speed, the feeding force, the rotational torque, the rotational speed, and the rotational energy obtained in the drilling test when the medium hard rock ground is used as the simulated ground. It is a table summarizing the correlation of the data obtained by the drilling test. (A) A table summarizing the average value, standard deviation, and coefficient of variation of various data obtained in the drilling test using soft rock ground, and (b) Average of various data obtained in the drilling test using medium-hard rock ground. It is a table that summarizes the values, standard deviations, and coefficients of variation. It is a graph which shows the change of the rotational torque, the rotational energy, and the power.

Hereinafter, the present invention will be described with reference to the drawings. As shown in FIG. 1, the drilling device 10 is a device for drilling holes by using a dry double pipe method using a down-the-hole hammer as an example. The drilling device 10 includes a traveling carriage 11, a rotating ring slide base 12, a guide cell 13, a drifter 14, and a centricer 15. In the present embodiment, an example of a tracked vehicle type traveling vehicle is given as the traveling vehicle 11, but a wheeled vehicle type traveling vehicle may be used. Reference numerals 16 and 17 are outriggers that stabilize the posture of the traveling bogie 11 during construction.

The rotary ring slide base 12 has a base portion 25 on which a support rod 21 supported by the traveling carriage 11 and a hydraulic cylinder 22 are pivotally supported, and a rotary ring portion 26 that is rotatable with respect to the base portion 25. The base portion 25 is pivotally supported by the support rod 21 and the hydraulic cylinder 22 supported by the traveling carriage 11, and is tilted by the expansion and contraction of the hydraulic cylinder 22 and the rotation of the support rod 21 due to the expansion and contraction of the hydraulic cylinder 23.

The rotary ring portion 26 is driven by the hydraulic cylinder 27 to rotate with respect to the base portion 25. The rotary ring portion 26 has a hydraulic cylinder 28 connected to the upper end portion of the guide cell 13. The hydraulic cylinder 28 changes the relative position of the guide cell 13 with respect to the rotating ring portion 26. As an example, the hydraulic cylinder 28 slides the guide cell 13 in an upright position with respect to the ground surface in the vertical direction to change the relative position of the guide cell 13 with respect to the rotating ring portion 26.

The guide cell 13 slidably supports the drifter 14 in the longitudinal direction. Although not shown, the guide cell 13 has a slide mechanism (not shown) that slides the drifter 14 along the longitudinal direction of the guide cell 13. Examples of the slide mechanism include a mechanism composed of a chain, a sprocket, a motor, and the like.

The drifter 14 has, for example, a shank rod that is rotationally driven by a hydraulic motor and a hammer (not shown) that is driven by hydraulic or pneumatic pressure and strikes the upper end of the shank rod. The drifter 14 gives rotation to the inner rod connected to the shank rod, and also gives a striking force to the steel pipe to be driven. A drilling bit is attached to the tip of the inner rod.

The centriser 15 is fixed to the lower end of the guide cell 13. The centriser 15 grips the steel pipe to be driven, the threaded joint of the steel pipe, and the threaded joint of the inner rod connected to the drilling bit.

The drilling device 10 has a construction management device 30. The construction management device 30 has a measurement control unit 31 and an operation panel 32. The measurement control unit 31 is connected to various sensors such as a rotary encoder, a pressure sensor, a current exchanger, an electromagnetic flow meter, an inclination sensor, and a depth sensor provided in the drifter 14 of the drilling device 10, and drilling using the drilling device 10. Receives detection signals from various sensors during hole work. The measurement control unit 31 calculates and processes the detection signals obtained from various sensors to generate measurement data, and stores the measurement data in a storage device (not shown). The measurement data at the time of construction is stored in the storage device provided in the measurement control unit 31, and is also transmitted to the data management device connected to the construction management device 30. Further, the measurement control unit 31 instructs the operation panel 32 to display using the measurement data.

The operation panel 32 is, for example, a display device having a touch panel. The operation panel 32 collectively displays the measurement data at the time of construction for each item, or displays the measurement data of only the necessary items as a graph. The display switching on the operation panel 32 is performed by an input operation on the touch panel provided on the operation panel 3.

Next, in order to establish the ground determination method, the simulated ground 40 is installed on the local ground so that the simulated ground 40 and the ground of the land (hereinafter referred to as the local ground) are in this order from the ground surface side, and the above-mentioned drilling is performed. A drilling test was performed by a small-diameter steel pipe pile method using the device 10.

As shown in FIG. 2, the simulated ground 40 used in the drilling test is a block-shaped ground having a width W = 1.5 m, a depth D = 1.0 m, and a height H = 1.5 m. The simulated ground 40 consists of two parts: a simulated ground that imitates the case where the ground is soft rock (hereinafter, soft rock ground) and a simulated ground that imitates the case where the ground is medium hard rock (hereinafter, medium hard rock ground). Created two simulated grounds. Strength of soft rock ground is set to 18N / mm ^2, the strength of the medium hard rock ground was set to 40N / mm ^2. The local ground has an N value of, for example, about 5, which is an index indicating the hardness of the ground. In the drilling test, drilling is performed at four locations on the upper surface of the simulated ground 40. In FIG. 2, the locations to be drilled are indicated by two-dot chain lines, and the reference numerals 40a, 40b, 40c, and 40d are attached to each location. In the drilling test, one steel pipe pile with a diameter of 165.2 mm and a length of 1.0 m and three steel pipe piles with a diameter of 165.2 mm and a length of 0.75 m were used, and the maximum length was 3.25 m (in FIG. 1). Drilling was performed to a depth of reference numeral H _max). Further, in the above-mentioned drilling test, the rotation speed and the feeding force of the drilling bit were kept constant. Specifically, the rotation speed of the drilling bit is 20 rpm, and the feeding force is 2 kN.

FIG. 3 is a graph showing fluctuations in drilling speed, feeding force, rotational torque, rotation speed, and rotational energy obtained in a drilling test when the soft rock ground is used as a simulated ground. As described above, in the drilling test, since the rotation speed and the feeding force of the drilling bit are held at a constant value, the fluctuation of the rotation speed and the feeding force of the drilling bit is small. It is considered that the parts where the rotation speed and the feeding force of the drilling bit fluctuate greatly are affected by the slipping and biting of the drilling bit with respect to the ground. Further, the drilling speed, the rotational torque, and the rotational energy fluctuate due to the influence of slippage and biting of the drilling bit with respect to the ground.

Then, when the drilling bit reaches the boundary between the soft rock ground and the local ground and shifts from the drilling of the soft rock ground to the drilling of the local ground (when the depth in the drilling work exceeds 1500 mm), the feeding force and The rotation speed of the drilling bit changes at almost the same value as that obtained when drilling the soft rock ground. On the other hand, the drilling speed increases due to the difference between the hardness of the soft rock ground and the hardness of the local ground, and the rotational torque and the rotational energy decrease.

FIG. 4 is a graph showing fluctuations in drilling speed, feeding force, rotational torque, rotation speed, and rotational energy obtained in a drilling test when a medium-hard rock ground is used as a simulated ground. In the case of the drilling test using medium-hard rock ground, as in the drilling test using soft rock ground, the rotation speed and feeding force of the drilling bit are maintained at constant values, so drilling is performed. Fluctuations in the number of revolutions of the bit and the feeding force are small. It is considered that the parts where the rotation speed and the feeding force of the drilling bit fluctuate greatly are affected by the slipping and biting of the drilling bit with respect to the ground. Further, the drilling speed, the rotational torque, and the rotational energy fluctuate due to the influence of slippage and biting of the drilling bit with respect to the ground. Since the medium-hard rock ground is harder than the soft rock ground, the drilling speed and the rotational torque are smaller than the values obtained in the drilling test using the soft rock ground. In addition, the drilling test using medium-hard rock ground is more susceptible to the effects of slipping and biting of the drilling bit on the ground than the drilling test using soft rock ground, so the rotation of the drilling bit Fluctuations in number, feeding force, drilling speed, rotational torque and rotational energy are expected to increase.

Then, when the drilling bit reaches the boundary between the medium-hard rock ground and the local ground and shifts from the drilling of the medium-hard rock ground to the drilling of the local ground (when the depth in the drilling work exceeds 1500 mm), The feeding force and the rotation speed of the drilling bit change at almost the same values as those obtained when drilling the medium-hard rock ground. On the other hand, the drilling speed increases due to the difference between the hardness of the medium-hard rock ground and the hardness of the local ground, and the rotational torque and the rotational energy decrease.

The above-mentioned rotational energy is calculated by the following equation (1) when the coefficient for determining the ground is α, the rotation speed is N, the rotation torque is T, the drilling bottom area is A, and the drilling speed is B. Will be done.

Rotational energy = α ・ (2π ・ N ・ T) / (A ・ B) ・ ・ ・ (1)

Further, the power (power) is calculated by the following equation (2).

Power (power) = (2, π, TN) / 60 ... (2)

FIG. 5 is a table summarizing the correlation of the data obtained by the drilling test. The table shown in FIG. 5 shows a correlation function obtained by correlating two data out of the four data of drilling speed, feeding force, rotational torque, and rotational speed by using, for example, the minimum square method. Further, the soft rock 1 shows the case where the drilling test is performed at the place of reference numeral 40a of the simulated ground 40 shown in FIG. 2, and the soft rock 2 shows the case where the hole is drilled at the place of reference numeral 40b of the simulated ground 40 shown in FIG. The case where the test was performed is shown. The soft rock 3 shows the case where the drilling test is performed at the position indicated by the reference numeral 40c of the simulated ground 40 shown in FIG. 2, and the soft rock 4 shows the case where the drilling test is performed at the position indicated by the reference numeral 40d of the simulated ground 40 shown in FIG. The case where the test was performed is shown. Further, the medium hard rock 1 shows the case where the drilling test is performed at the portion of the simulated ground 40 shown in FIG. 2 at the location of the reference numeral 40a, and the medium hard rock 2 is the location of the simulated ground 40 shown at FIG. The case where the above drilling test is performed is shown in. The medium hard rock 3 shows the case where the drilling test is performed at the position indicated by the reference numeral 40c of the simulated ground 40 shown in FIG. 2, and the medium hard rock 4 is the position indicated by the reference numeral 40d of the simulated ground 40 shown in FIG. The case where the above drilling test is performed is shown in.

In FIG. 5, when it is determined that there is a correlation between the two data when the correlation coefficient is 0.7 or more in the correlation using the two data, the rotation occurs in each part of the soft rock ground and the medium hard rock ground. It can be determined that there is a correlation between the number and the rotational torque.

FIG. 6A is a table summarizing the average value, standard deviation, and coefficient of variation of various data obtained in the drilling test using soft rock ground. Further, FIG. 6B is a table summarizing the average value, standard deviation, and coefficient of variation of various data obtained in the drilling test using the medium-hard rock ground. The number of data (number of samples) used to obtain these values was 1824 in the drilling test using soft rock ground and 2143 in the drilling test using medium hard rock ground. The number of samples differs between the soft rock ground and the medium hard rock ground because, of the obtained data, for example, only the data whose feeding force is close to 2 kN is used.

Here, the propulsion energy shown in FIG. 6 is obtained by the following equation (3).

Propulsion energy = β × (feeding force / drilling cross-sectional area) ・ ・ ・ (3)

The symbol β represented by the equation (3) is a propulsion coefficient.

As described above, in the drilling test, since the feeding force and the rotation speed of the drilling bit are constant, the coefficient of variation of the feeding force, the rotation speed, and the propulsion energy can be determined even if the simulated ground is soft rock ground. , Even in medium-hard rock ground, the value is small. On the other hand, the coefficient of variation of drilling speed, rotational torque, rotational energy and power is high regardless of whether the simulated ground is soft rock ground or medium hard rock ground.

Finally, the relationship between rotational torque, rotational energy, and power will be described with reference to FIG. 7. In FIG. 7, the symbol “■” indicates rotational torque, the symbol “●” indicates rotational energy, and the symbol “▲” indicates power. The value of the rotational torque is shown on the left vertical axis, and the unit of the rotational torque is kNm. The value of the rotational energy is shown on the right vertical axis, and the unit of the rotational energy is kN / cm ² (= ^{kN cm / cm 3} ). Further, the value of power is shown on the right vertical axis, and the unit of power is kW. Although the units of the rotational energy and the power are different, since the numerical ranges are similar, the values of the rotational energy and the power are shown on the right vertical axis in FIG. 7.

As shown in FIG. 7, the coefficient of variation of the power is small regardless of whether the simulated ground is soft rock ground or medium hard rock ground, and the fluctuation with respect to the difference in hardness of each simulated ground is small. On the other hand, the rotational energy has a large coefficient of variation in each of the simulated grounds, and also has a large variation with respect to the difference in hardness of each simulated ground. Further, the coefficient of variation of the rotational torque is small in each of the simulated grounds, but the fluctuation with respect to the difference in hardness of each simulated ground is large. However, depending on the ground, the drilling bit may slip and torque may not be applied. In this case, it is necessary to consider the drilling speed. Therefore, the hardness of the target ground can be determined by a quantitative ground determination method using rotational energy, which has a large coefficient of variation but a large variation with respect to the difference in hardness of the simulated ground.

As a result, in the present embodiment, by performing the above-mentioned drilling test, the drilling work is performed while observing the transition of the rotational energy calculated from various data in the ground reinforcement work, and the rotational energy fluctuates significantly ( Since the hardness of the support layer in the ground is harder than the hardness of the ground near the ground, the rotational energy actually increases when it reaches the support layer in the ground), and it reaches the support layer in the ground. I found a way to determine if it was done (whether it was rooted or not).

Therefore, using the drilling device 10 shown in FIG. 1, it is possible to carry out ground reinforcement work using the ground determination method of the present embodiment. Specifically, when the drilling device 10 shown in FIG. 1 is used to drill a hole and place a steel pipe, the measurement control unit 31 of the construction management device 30 calculates and processes the acquired detection signal for measurement. The data is calculated, and the calculated measurement data is displayed on the display unit of the operation panel 32. Further, the measurement control unit 31 of the construction management device 30 determines whether or not the drilling and steel pipe placing work has reached the support layer in the ground from the rotational energy and depth displayed on the display unit of the operation panel 32. Judgment (evaluation). This determination is a determination as to whether or not the rotational energy has changed significantly. Then, when it is determined that the measurement control unit 31 of the construction management device 30 has reached the support layer in the ground, the measurement control unit 31 of the construction management device 30 displays a display to that effect on the display unit of the operation panel 32. conduct. When making the above determination, the measurement control unit 31 of the construction management device 30 stores in advance the amount of fluctuation of the rotational energy when it reaches the support layer in the ground as a threshold value. When the construction management device 30 stores the threshold value, the measurement control unit 31 of the construction management device 30 can automatically determine (evaluate) whether or not the drilling work has reached the support layer in the ground using the threshold value. The construction manager may make the above determination.

At the time of the above-mentioned ground reinforcement work, the depth (depth) from the existing columnar chart or the like to the support layer in the ground may be predicted (calculated). In such a case, the drilling work is performed without keeping the rotation speed and feeding force of the drilling bit constant up to the vicinity of the support layer in the ground, and the drilling work and the steel pipe driving work are performed to the desired depth. After the drilling, the drilling and the casting of the steel pipe can be performed by keeping the rotation speed and the feeding force of the drilling bit constant.

In the present embodiment, the hardness of the target ground is determined by quantitative ground determination using rotational energy, but the value obtained by adding the rotational energy and the propulsion energy (hereinafter referred to as the added value) is used to determine the hardness of the target ground. It is also possible to determine the hardness. For example, when the drilling work is performed with the feeding force constant, the value of the propulsion energy becomes a substantially constant value. As a result, it is considered that the fluctuation of the added value is not the fluctuation of the propulsion energy but the fluctuation of the rotational energy. Therefore, in this case as well, the hardness of the target ground can be determined in the same manner as in the present embodiment.

In this embodiment, the small-diameter steel pipe pile method is taken as an example of the ground reinforcement method, but if it is a method of forming a synthetic pile after drilling work until it reaches the support layer in the ground, this method is used. It is possible to apply the invention.

10 ... Drilling device, 30 ... Construction management device, 31 ... Measurement control unit, 32 ... Operation panel, 40 ... Simulated ground

Claims (5)

It is a ground judgment method when drilling holes and placing steel pipes using a double pipe type down-the-hole hammer.
The drilling using the drilling bit, and the first boring step of executing holds KyuSusumu force during drilling and the rotational speed of the drilling bit constant,
Acquisition step for acquiring the rotation speed of the drilling bit, the rotational torque applied to the drilling bit, the drilling speed of the drilling bit, and the depth of the drilling bit in the first drilling step. When,
The coefficient for determining the ground is α, the bottom area of the drilling bit is A, the rotation speed of the drilling bit obtained by the acquisition step is N, the rotation torque applied to the drilling bit is T, and the above. Rotational energy represented by the following equation (1), where B is the drilling speed of the drilling bit. Rotational energy = α · (2π · N · T) / (A · B) ... (1)
And the process of calculating
An evaluation step of determining whether or not the drilling and the placement of the steel pipe have reached the support layer in the ground based on the fluctuation of the rotational energy.
A ground determination method characterized by having. In the ground determination method according to claim 1,
At least the rotational energy of the number of rotations of the drilling bit, the rotational torque applied to the drilling bit, the drilling speed of the drilling bit, the depth of the drilling bit, and the rotational energy is displayed. A ground determination method characterized by having a display process. In the ground determination method according to claim 1 or 2.
An estimation process that estimates the depth of the support layer in the ground, and
A second drilling step of drilling to a depth near the support layer in the ground, and
Have,
The ground determination method, characterized in that the first drilling step is executed following the second drilling step. In the ground determination method according to any one of claims 1 to 3,
The ground determination method is characterized in that the drilling is performed by using the small-diameter steel pipe pile method. In a drilling device that drills holes and drives steel pipes until it reaches the support layer in the ground using a double-tube down-the-hole hammer.
An acquisition unit that acquires the rotation speed of the drilling bit for drilling, the rotational torque applied to the drilling bit, the drilling speed of the drilling bit, and the depth of the drilling bit.
The coefficient for determining the ground is α, the bottom area of the drilling bit is A, the rotation speed of the drilling bit obtained by the acquisition unit is N, the rotation torque applied to the drilling bit is T, and the above. Rotational energy represented by the following equation (2), where B is the drilling speed of the drilling bit. Rotational energy = α · (2π · N · T) / (A · B) ... (2)
And the calculation unit that calculates
An evaluation unit that determines whether or not the drilling and the placement of the steel pipe have reached the support layer based on the fluctuation of the rotational energy.
A drilling device characterized by having.

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