JP2008255765A - N-value detection method, n-value detector, and pile hole drilling unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a pile hole is obliquely formed because a presently mainstream pile hole drilling unit employing a hydraulic motor as a driving source cannot detect a precise N-value in real time during ground drilling operations, and because a direction of a drilling bucket is changed when the pile hole drilling unit collides with an undrillable obstacle such as a rock in the ground. <P>SOLUTION: The N-value of the ground midway through the drilling operation is detected from an input pressure value of the hydraulic motor as the driving source of the drilling bucket for drilling the ground, and a value of a rotational period of the hydraulic motor. Additionally, the N-value is monitored in real time during the drilling operation, so that the obstacle, a hard stratum, etc. in the ground can be detected to prevent the oblique formation of the pile hole. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an N value detection method, an N value detection device, and a pile provided with an N value detection means that are useful when excavating a pile hole in a work for excavating a pile hole for a built pile or an existing pile on site. The present invention relates to a hole drilling device.

  There are two methods for excavating a pile hole in the ground and erecting a pile in this pile hole: a method of building a pile in the field and a method of erecting a pile already formed in the shape of the pile in the pile hole.

  In-situ constructed piles form a pile by excavating a pile hole using a drilling device, and inserting concrete into the pile hole after inserting a reinforcing bar and tremy pipe. On the other hand, a prefabricated pile is a method of installing a pile by a method of driving a formed pile into a hole excavated or a method of screwing a pile whose tip is threaded into the ground. Either method requires drilling holes for piles in the ground.

  For the pile hole, the ground layer with a hardness of N value or more is determined as the support layer of the pile hole based on the ground condition previously grasped by the boring survey, and at least the pile hole with the depth up to this support layer is defined. It is necessary to drill. Therefore, it is necessary to grasp the N value of the stratum at the excavated position along with information on the depth of the pile hole.

  Moreover, it is necessary to form the pile hole for forming the built-up pile correctly vertically, and if this pile hole is inclined and formed from the vertical line, it will have to be excavated again, resulting in great costs. There is a problem that.

  The reason why the pile hole is tilted is that the excavation bucket bends against a rock or other obstacle that cannot be excavated in the ground, or the excavation bucket gradually bends due to the inclination of the hard stratum in the ground. There are many cases. If the N value of the ground excavated during excavation work and changes in the N value can be known in real time, it will be possible to predict the occurrence of defects that occur when the pile hole is tilted. Useful. Moreover, it is an effective excavation method for excavating an accurate pile hole to advance the excavation work of the pile hole while comparing the N value grasped in real time with the result of the drilling survey carried out in advance.

  As a conventional technique, Japanese Patent Application Laid-Open No. 2006-348515 discloses a method of grasping an N value while excavating. The above publication relates to a drilling device using an electric motor, and determines the integrated value of the current that flows to the electric motor when excavating the ground, and the hardness of the stratum being excavated by determining the load for excavating the ground from that value Discloses a method of grasping the N value, which is an index of the above.

  Currently, many types of excavators for pile holes use a hydraulic motor, and the method for detecting the N value disclosed in the above publication is applicable to excavators using a hydraulic motor. I can't. In a conventional pile hole excavator that uses a hydraulic motor as the drive source for the excavating bucket, the operating conditions of the excavator during operation by the operator and the experience received by the operator are known, and the ground conditions are accurate. There was a problem that the N value could not be grasped in real time.

  JP 2006-348515 A

  There is a problem that an accurate N value cannot be detected in real time during excavation work on the ground for a pile hole excavation apparatus that uses a hydraulic motor that is currently mainstream as a drive source. In addition, when hitting an obstacle that cannot be excavated such as a rock in the ground, the direction of the excavation bucket may be bent, and as a result, the pile hole is inclined and formed.

  In view of the above-described problems, the present invention provides an N value detection method and a detection device thereof capable of detecting the N value of the ground in real time during excavation work of a pile hole excavator using a hydraulic motor as a drive source for the excavation bucket. An object of the present invention is to provide a pile hole excavating apparatus provided with the N value detection method, which can prevent the pile hole from being inclined and formed.

  In order to achieve the above object, an N value detection method according to a first solving means of the present invention includes a excavation bucket for excavating the ground, and the excavation bucket is rotated by a hydraulic motor. It is characterized in that the pressure for driving the motor and the rotation cycle of the excavation bucket are detected, and the N value of the ground is calculated from the pressure and the rotation cycle.

  According to the first solution described above, the N value of the ground can be detected only by determining the input pressure value of the hydraulic motor that drives the excavation bucket and the value of the rotation period of the hydraulic motor. The N value of the ground can be detected.

  A second solving means of the present invention is the N value detection method of the first solving means, characterized in that the rotation cycle of the excavation bucket is obtained from pressure fluctuations of a hydraulic motor, and the rotation cycle of the excavation bucket No special detector is required to determine the device, and the configuration of the apparatus is simplified.

  An N value detection device according to a third solution of the present invention includes a excavation bucket for excavating the ground, and the excavation bucket detects a pressure for driving the hydraulic motor in a ground excavation device that is rotationally driven by a hydraulic motor. A pressure detection unit; a rotation cycle detection unit that detects a rotation cycle of the excavation bucket; and an N value calculation unit that calculates an N value of the ground from the pressure and the rotation cycle. The N value of the ground can be detected only from the input pressure value of the hydraulic motor to be operated and the value of the rotation cycle of the hydraulic motor.

  A fourth solving means of the present invention is the N value detecting device of the third solving means, wherein the rotation period detecting means excavates at a rotational speed obtained from a rotational speed sensor that measures a rotational speed of the excavating bucket. The rotation period of the bucket is calculated.

  A fifth solving means of the present invention is the N value detecting device of the third solving means, wherein the rotation period detecting means obtains a rotation period of the excavation bucket from a pressure fluctuation of a hydraulic motor. .

  A pile hole excavation apparatus according to a sixth solution of the present invention includes a excavation bucket for excavating the ground, and the excavation bucket is a pile hole excavation apparatus that is rotationally driven by a hydraulic motor, and the pressure that drives the hydraulic motor. Pressure detection means for detecting the rotation, rotation period detection means for detecting the rotation period of the excavation bucket, N value calculation means for calculating the N value of the ground from the pressure and rotation period, and the N value calculated by the calculation means A pile hole excavating apparatus comprising ground information management means for managing ground information including

  The seventh solving means of the present invention is a pile hole excavating apparatus of the sixth solving means, wherein the ground information management means detects an abnormal value of N value, and deposits that cannot be excavated in the ground. It is provided with a warning function that warns that it exists.

  An eighth solving means of the present invention is the pile hole excavating apparatus of the sixth solving means, wherein the rotation period detecting means excavates at a rotational speed obtained from a rotational speed sensor for measuring a rotational speed of the excavating bucket. The rotation period of the bucket is calculated.

  A ninth solving means of the present invention is the pile hole excavating apparatus of the sixth solving means, wherein the rotation period detecting means obtains the rotation period of the excavation bucket from the pressure fluctuation of the hydraulic motor.

  As described above, the N value detection method of the present invention can be obtained if the input pressure value of the hydraulic motor that is the drive source of the excavation bucket that excavates the ground and the value of the rotation period of the hydraulic motor are known. The N value of the ground can be easily detected.

  Furthermore, the rotation cycle of the excavation bucket can be determined from the pressure fluctuation of the hydraulic motor, that is, the pulsation caused by the rotation of the hydraulic motor, and it is necessary to provide a detection means for determining the rotation cycle of the excavation bucket. In addition, the configuration of the device for detection can be made simpler.

  As a result, the N value of the ground can be known in real time during excavation work, and the configuration of the detection method can be very simple, so that a great effect can be achieved despite the low cost.

  The N value detection method, N value detection device, and pile hole excavation device of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by a present Example.

  FIG. 1 is an explanatory view showing an essential part of an N value detection method and apparatus and an excavation bucket used in a pile hole excavation apparatus and a drive unit for driving the excavation bucket, and FIG. It is explanatory drawing which shows the whole excavation apparatus.

  A pile hole excavating apparatus 1 used for excavating a pile hole in the ground called an earth drill method is provided with a excavation bucket 2 at the tip of a kelly bar 3 suspended from the tip of a boom that extends as shown in FIG. Composed. The excavation bucket 2 has a structure in which a excavation cutter for excavation is provided on a bottom portion of a cylindrical bucket shape, and the earth and sand of the ground is taken into the excavation bucket 2 by rotationally driving the excavation bucket 2. The ground is excavated by continuously rotating the excavation bucket 2, and the earth and sand accommodated in the excavation bucket 2 is sequentially discharged to the ground to advance the excavation work. The kelly bar 3 that supports the excavating bucket 2 is suspended from the tip of the boom of the pile hole excavating device 1 and is held by the kelly winch 6 so as to be movable in the vertical direction.

  When viewed from the bottom of the excavation bucket 2 and the excavation direction, a cutter for excavation is provided at the tip, and a side cutter is provided at the side of the excavation bucket 2, and excavation is performed in the depth direction of the pile hole by the excavation cutter. At the same time, a pile hole having a predetermined diameter is formed by the side cutter.

  The hydraulic motor 4 that rotationally drives the excavation bucket 2 is connected to a hydraulic unit 41 as shown in FIG. 3, and operates by discharging hydraulic oil of a predetermined pressure and taking in hydraulic oil discharged from the hydraulic motor 4. Circulate the oil. The pressure of the hydraulic oil entering the hydraulic motor 4 is detected by the pressure sensor 42.

  The rotation speed of the excavation bucket 2 is detected by a rotation speed sensor 7 (not shown). If the rotation speed of the excavation bucket 1 is known, the rotation cycle of the excavation bucket 1 can be easily derived.

  Next, a procedure for detecting the N value will be described. In the earth drilling method, first, the kelly bar 3 of the pile hole excavating apparatus 1 is first aligned with the center position of the pile hole, and excavation is started. If excavation is carried out to the depth where the surface casing that protects the pile hole near the surface is built, the surface casing is installed. By injecting a stable liquid suitable for the soil, the pile hole that was excavated is prevented from collapsing, and it advances to the support layer of the pile, and it is embedded in the support layer (a hole of a predetermined depth excavated in the support layer). Then, the excavation work of the pile hole is completed.

  It is necessary to excavate the pile to a stratum of a specified hardness, and that stratum should be used as a support layer for the pile hole, but in conventional excavation work, the drilling depth and drilling investigation and discharge performed in advance were performed. In the present invention, the N value of the formation being excavated can be known in real time by calculating the N value according to the following procedure.

The N value is obtained by the following equation (A).
N = a · p · T−b (A)
Here, N is the N value, p is the pressure of the hydraulic oil input to the hydraulic motor, T is the rotation period of the excavation bucket 2, and a and b are constants related to the excavation conditions. . Since a and b can be known in advance from the excavation conditions, the N value can be easily obtained using the above equation (A) if the pressure p applied to the hydraulic motor and the rotation period T of the excavation bucket 2 are known.

Next, the grounds for obtaining the N value using the formula (A) will be described. N value and viscosity coefficient of earth and sand in the ground are defined by different methods, but their physical meanings are correlated within a range where earth and sand can be regarded as a viscous body, and viscosity coefficient μ and N value are shown below ( Approximation is made using equation (1).
N = c · μ (1)
Here, N is the N value of the formation and c is a constant. Strictly speaking, the N value and the viscosity coefficient may not be expressed by a simple linear relationship such as the equation (1), but since the value of the N value is not strictly defined originally, It is considered that there is no problem in practical use.

Torque T _B required for driving the bucket 2 excavating sediment, if the speed of the bucket 2 is low may ignore the force due to dynamic pressure, given only torque generated by the frictional force ( 2) Expressed by the formula.
T _B = μ · A · ω (2)
Here, μ is a viscosity coefficient, ω is a rotation angular velocity of the excavation bucket 2, and A is a constant determined by the length of the cutting blade of the excavation bucket 2. On the other hand, the relationship between the drive torque T _B of the excavation and the generated torque T _P of the hydraulic motor is represented by the following formula (3).
T _P = T _B + T _M (3)
Here, _TM is the loss torque of the mechanical system.

Loss torque T _B of generated torque T _P and mechanical hydraulic motor can be expressed by each (4) and (5).
T _P = (V / 2π) · p (4)
T _M = D _M · ω (5)
Here, V is the volume of the hydraulic motor, D _M are constants that cause the loss of the mechanical system.

From the expressions (2) to (5), the N value can be expressed by the following expression (6).
N = (V · π ² · pT−D _M ) / cA (6)
In the equation (6), p is the pressure of the hydraulic oil, and T is the rotation period of the excavation bucket 2. Since all other parameters are constants, the N value can be obtained by detecting the above two parameters.

  The expression (A) is obtained by arranging the expressions (6) and arranging the pressure p and constants other than the rotation period T.

  In the above description, the N-value induction formula (6) is obtained on the assumption that the hydraulic motor directly drives the excavation bucket 2 without using a transmission. n is only included as a new constant in the equation (6), and is still calculated by two parameters of the hydraulic oil pressure p and the rotation period T of the excavating bucket 2.

  FIG. 5 is an explanatory diagram showing a flow of detecting the N value and managing the information, and FIG. 5 detects the N value by obtaining the rotation period of the excavation bucket 2 based on the rotation speed detected by the rotation speed sensor 7. An example is shown. The hydraulic motor 4 has a valve opening / closing cycle every rotation, and pulsation occurs in the pressure acting on the hydraulic motor 4 as shown in FIG. The pressure value used for the detection of the N value is the pressure value p that is the average value of the pressure obtained by the pressure average value calculation means 81, and the rotation period of the excavation bucket 2 calculated from the rotation speed detected by the speed sensor 7. At the same time, the N value calculation means 82 obtains the value using equation (A).

  The N value calculated by the N value calculation means 82 is recorded by the ground information management means 83 including the depth information obtained by the depth detection means (not shown). When an abnormal value such as a sudden change in the value of N is indicated, the ground abnormality warning means 84 issues a warning. Further, the excavation information such as the N value, the excavation depth, and the warning information is clearly displayed on the display device 85 to the operator.

  FIG. 6 shows an example in which the N value is detected by obtaining the rotation period T from the pressure fluctuation of the hydraulic motor, that is, the pulsation caused by the rotation of the hydraulic motor, without providing the angular velocity sensor as the angular velocity detecting means. As shown in FIG. 4, the input pressure of the hydraulic motor 4 obtained from the pressure sensor 42 pulsates every rotation, and the period of one rotation of the hydraulic motor 4 can be detected by detecting the extreme value. The rotation cycle detection unit 91 is a detection unit that detects the rotation cycle of the hydraulic motor 4 by detecting the extreme value of the pulsation of the hydraulic motor 4, and includes a dedicated detector for detecting the rotation speed of the hydraulic motor 4. The rotation period of the hydraulic motor 4 can be detected without providing it.

  In a pile hole excavator using a hydraulic motor as a driving means for the excavation bucket 2 as in the pile hole excavator of the present invention, when the hardness of the ground changes, the rotational speed of the excavation bucket 2 changes and is input to the hydraulic motor. The pressure applied also changes. Therefore, it is possible to easily detect the N value of the formation by detecting these two parameters.

  As shown in FIGS. 5 and 6, in the ground information management means 83, the vibration information obtained from the depth detection means (not shown) is combined with the N value to obtain the relationship between the depth of the ground and the N value. In the drilling survey conducted in advance, it is soil information of only a part of the construction section, and accurate information on the ground at the position of the pile hole can be obtained.

  As for the support layer of the pile hole, depth information and the N value of the support layer are known by a boring investigation conducted in advance. Since the depth information and the N value information can be understood in real time by the pile hole excavation device of the present invention, it is possible to accurately excavate the depth to be excavated after reaching the support layer. The confirmation work is no longer necessary, and the work becomes more efficient.

  When there are obstacles such as rocks in the ground, if these obstacles are hard, the cutters provided on the bottom and side surfaces of the excavation bucket 2 may be damaged. In addition, the excavation path may be bent by an obstacle, and the verticality of the pile hole may not be maintained. If excavation is performed while the pile hole is tilted, the pile hole is inclined and formed, which necessitates re-excavation of the pile hole, resulting in a great expense.

  The pile hole excavation device of the present invention includes a ground abnormality warning means for discriminating the state of the ground from the information obtained by the N value detection means and warning the operator. In addition to displaying the N value on the monitor, warning that there is an obstacle in the ground that may cause damage to the cutter or cause the pile hole to be skewed by flashing the buzzer or warning lamp. To do. In other words, it is possible to prevent work delays due to cutter breakage and re-excavation due to inclined pile holes.

  For pile hole drilling equipment that uses a hydraulic motor as the mainstream at present, it is impossible to detect an accurate N value in real time during ground excavation work, so obstacles such as rocks in the ground that cannot be excavated This causes problems such as damage to the excavation bucket and tilting of the excavated pile hole due to obstacles in the ground. As a result, enormous costs are incurred.

  The present invention provides an N value detection method and a detection device thereof capable of detecting the N value of the ground in real time during excavation work of the pile hole, and the pile hole is formed to be inclined by providing the N value detection method. Provided is a pile hole drilling device that can prevent this. Even if there are obstacles that cannot be excavated, such as rocks in the ground, the N-value detection means can quickly detect the presence of the obstacles, prevent damage to the excavation bucket, and tilt the pile holes due to obstacles in the ground. It is possible to detect the formation. As a result, it is possible to secure high productivity by preventing breakage of the cutting bucket due to obstacles in the ground, and to suppress the cost of re-digging due to the tilted formation of pile holes Can contribute greatly to the industry.

  It is explanatory drawing which shows the principal part of the pile hole excavation apparatus of a present Example.   It is an external view which shows the whole pile hole excavation apparatus of a present Example.   It is explanatory drawing which shows the relationship between an excavation bucket, a hydraulic motor, and a drive part.   It is explanatory drawing which shows the fluctuation | variation of the input pressure of a hydraulic motor.   It is explanatory drawing which shows the flow which detects N value.   It is explanatory drawing which shows the flow by another method regarding N value detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pile hole excavator 2 Excavation bucket 3 Kelly bar 4 Hydraulic motor 5 Kelly bar support stand 6 Kelly winch 7 Rotational speed sensor 8 Management device 9 Management device 41 Hydraulic unit 42 Pressure sensor 81 Pressure average value calculation means 82 N value detection means 83 Ground information Management means 84 Ground abnormality warning means 85 Display device 91 Rotation period calculation means

Claims (9)

  In a ground excavator that includes a excavating bucket for excavating the ground, and the excavating bucket is rotationally driven by a hydraulic motor, a pressure for driving the hydraulic motor and a rotation cycle of the excavating bucket are detected, and the pressure and the rotation cycle are detected. An N value detection method characterized by calculating an N value of the ground.   The N value detection method according to claim 1, wherein the rotation period of the excavation bucket is obtained from pressure fluctuations of a hydraulic motor.   In a ground excavator provided with a excavating bucket for excavating the ground, wherein the excavating bucket is rotationally driven by a hydraulic motor, a pressure detecting means for detecting a pressure for driving the hydraulic motor, and a rotational period for detecting a rotational period of the excavating bucket An N value detecting device comprising: a detecting means; and an N value calculating means for calculating an N value of the ground from the pressure and the rotation period.   The N value detection device according to claim 3, wherein the rotation period detection unit calculates a rotation period of the excavation bucket based on a rotation speed obtained from a rotation speed sensor that measures the rotation speed of the excavation bucket.   The N value detection device according to claim 3, wherein the rotation period detection unit obtains a rotation period of the excavation bucket from a pressure fluctuation of a hydraulic motor.   A pile hole excavating apparatus that includes a excavating bucket for excavating the ground, the excavating bucket being rotationally driven by a hydraulic motor, and a pressure detecting means for detecting a pressure for driving the hydraulic motor, and detecting a rotation period of the excavating bucket A rotation period detecting means for performing, an N value calculating means for calculating an N value of the ground from the pressure and the rotation period, and a ground information managing means for managing ground information including the N value calculated by the calculating means. Pile hole drilling device characterized by.   The pile hole excavation according to claim 6, wherein the ground information management means includes a warning function that detects an abnormal value of N value and warns that there is a sediment that cannot be excavated in the ground. apparatus.   The pile hole excavating apparatus according to claim 6, wherein the rotation period detecting means calculates a rotation period of the excavation bucket based on a rotation speed obtained from a rotation speed sensor that measures the rotation speed of the excavation bucket.   The pile hole excavating apparatus according to claim 6, wherein the rotation period detecting means obtains a rotation period of the excavation bucket from a pressure fluctuation of a hydraulic motor.

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