JPS6324122A - Laying method for magnetic field producing cable for position measurement by underground drilling machine - Google Patents

Abstract

PURPOSE:To obtain the real quantity of horizontal displacement by laying going and returning lines of a magnetic field producing loop cable across the construction plan line of an underground drilling machine on the ground surface at intervals of distance corresponding to the construction plan depth of the underground drilling machine. CONSTITUTION:The reception level ratio R of a magnetic field detecting element provided in the underground drilling machine 4 to the equal quantities of horizontal displacement of a magnetic field detecting element is right affected inverse ways by the depth D of the element and the laying interval l of the magnetic field producing cable to the construction plan line on the ground surface to each other. Consequently, the going and returning lines of the magnetic field producing cable 6 are laid in a loop across the construction plane line 7 on the ground surface 1 so that the interval is increased at a constant rate initially from a starting vertical shaft 2 to an arrival vertical shaft 3 corresponding to the depth variation of the digging-depth program line 5, held equal from the point where the digging depth is largest to the point where the depth begins to decrease, and decreased at the same rate with the depth variation until the arrival vertical shaft 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of laying a magnetic field generating cable installed to measure the underground position of an underground excavator on the ground surface.

(Prior Art) When excavating underground using an underground excavator, an important issue is whether or not the excavation can be carried out according to the construction plan.

For this reason, conventionally, the position of the excavator is constantly monitored during excavation work, and if something deviates from the construction plan, the position of the excavator is immediately corrected.

This monitoring means generally uses the straightness of laser light to control the excavator's attitude, or oscillates electromagnetic waves from within the excavator and tracks them on the ground surface to confirm the underground position of the excavator. Measures such as doing this have been adopted. However, in this case, although it is possible to adopt the former when the construction plan line is a straight line, it is difficult to use it when the construction plan line is a curve, and in the latter case, it is difficult to use it when the construction plan line is curved. However, this is often impossible due to terrain etc.

Therefore, new means have been proposed to replace these conventional monitoring means. For example, there is a device described in Japanese Patent Application Laid-Open No. 60-23049.8.To briefly introduce this, it is a device that is parallel to both sides of the construction plan line on the ground surface, and that has a separation distance from the plan line. A single magnetic field generating cable is equally laid in a loop 7, both ends of which are connected to an AC power source, while a magnetic field detector is attached to the underground excavator and a current is passed through the magnetic field generating cable laid on the ground surface. This system generates a magnetic field, which is detected by a magnetic field detector installed on an excavator working underground, and the signal is calculated by a controller that issues a command to correct the excavator's attitude.

Compared to existing similar devices, this proposed underground position measuring device for excavators can be automated, does not require tracking and scanning of the excavator, and is not limited to straight-line excavation. There are devices that can also perform curved excavation, but when installing the reciprocating lines of the magnetic field generation cable on the ground surface, they are simply laid across the construction line of the underground excavator on the ground surface at equal intervals on both sides. Currently, this method does not take into account the depth of the excavator underground.

On the other hand, according to research by the inventors, the method of laying magnetic field generating cables as described above has been improved, and the magnetic field generated from the magnetic field generating cable is received by a magnetic field detection element installed in an underground excavator. Even if we try to find the horizontal displacement (the amount of deviation from the construction plan line), it will inevitably be affected by the depth at the current position of the underground excavator, and it turns out that the true horizontal displacement cannot be found. Ta. To accurately determine this, it was necessary to provide depth information and perform correction calculations each time.

(Problems to be Solved by the Invention) In this way, when attempting to perform measurements using the previously proposed position measuring device for an underground excavator, it is difficult to determine the depth of the underground excavator when laying a magnetic field generating cable. Because no consideration is taken, it is not possible to determine the true amount of horizontal displacement of the underground excavator, especially when the construction plan line is changed to a depth of 6 degrees, making the measurement unreliable. The present invention has been researched and developed in view of this point, and even if the planned construction line is one where the depth is changing, the magnetic field generating cable can be connected in consideration of the change in depth. Based on the knowledge that if the magnetic field detection element installed in the underground excavator is installed, the true amount of horizontal displacement can be obtained by using the data detected by the magnetic field detection element installed in the underground excavator without any correction. To this end, the present invention attempts to provide a new method for laying a magnetic field generating cable for position measurement of an underground excavator.

(Means for Solving the Problem) Therefore, the present invention lays a reciprocating line of a magnetic field generation cable on the ground surface to generate a magnetic field, and receives the magnetic field with a magnetic field detection element in an underground excavator. To measure the underground position of an underground excavator, place a magnetic field on both sides of the planned construction line of the underground excavator at a distance corresponding to the planned construction depth of the underground excavator. This is a solution to the above problem by installing a reciprocating line of the generation cable.

(Function) For example, the ratio of the strength of the magnetic field from the ground surface that each pair of magnetic field detection elements receives changes depending on the amount of horizontal displacement of the magnetic field detection elements, and also depends on the depth of the detection elements from the ground surface. Change. In addition, this value also changes depending on the distance between the round trip lines of the magnetic field generating cables that sandwich the construction plan line on the ground surface.

There is a correlation between the horizontal displacement amount, the depth, and the distance between the two magnetic field detection elements.

Therefore, by setting the separation distance of the reciprocating lines in order to cancel the influence of the depth on the ratio of the magnetic field strength received by the pair of magnetic field detecting elements, and by laying the reciprocating lines according to the depth, the reception by the pair of magnetic field detecting elements is The value of the ratio of magnetic field strength directly corresponds to the true amount of horizontal displacement.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

First, prior to the explanation, we will briefly explain how the underground depth obtained through research by the inventors affects the amount detected by the magnetic field detection element.

FIG. 3 is a diagram showing the positional relationship of the magnetic field generating cable laid on the ground surface, the construction plan line on the ground surface, and the magnetic field detection element underground.

1 indicates the ground surface, 6a and 6b are the return lines and return lines of the magnetic field generating cables that are laid in a reciprocating manner at equal distances between the construction planned line 7 on the ground surface, 11a, + ll
b is a pair of magnetic field detection elements underground. It is assumed that the detection directions of the magnetic field detection elements 11a and 11b are orthogonal to each other, and each moves at an inclination of 45° with respect to the perpendicular line.

Now, in the same figure, the distance from the magnetic field generation cables 6a and 6b to the construction line on the ground surface is L/2, and the distance (depth) from the intersection center point of the magnetic field detection elements 11a and llb to the ground surface is D, and magnetic field detection element 11a,
The amount of horizontal displacement of the intersection center point of llb from the construction plan line 7 is X, and the horizontal distance between the center point and the magnetic field generating cables 6a and 6b is each X2. X, , the distance from the concentric point to the magnetic field generating cables 6a, 6b is γ7. R1 magnetic field generating cables 6a and 6b are respectively centered, and the angles formed by the perpendicular lines thereof and the intersection center points of magnetic field detection elements 11a and llb are respectively θ.
2. Let θ be.

At this time, if the horizontal displacement amount X of the magnetic field detection elements 11a and 11b is set to the right direction with the construction plan line as the origin, then the following equation holds true.

X, =-CX-L/2), X2=(X+L/2
) 1 Also, each magnetic field detection element 11a at this time,
Regarding the strength of the magnetic field received by llb, since the magnetic field detection element has directivity and receives the magnetic fields from the two magnetic field generating cables 6a and 6b, the following relational expression holds true.

Here, vll is the electromotive force generated when the magnetic field detection element 11b receives the magnetic field generated from the magnetic field generation cable 6b.+2 is the electromotive force generated when the magnetic field detection element 11a receives the magnetic field generated from the magnetic field generation cable 6b. The electromotive force generated when the magnetic field generated from the magnetic field generating cable 6a is received by the magnetic field detection element Llb is the electromotive force generated when the magnetic field generated from the magnetic field generation cable 6a is received by the magnetic field detection element 11a.
V22 Each pressure K Common coefficient I/2π(I
: cable current, π: pi) are omitted.

From the above relational expressions, it can be seen that the amount of magnetic field received by each magnetic field detection element 11a, llb is greatly influenced by D and L.

If the ratio of the strength of the magnetic fields received by each magnetic field detection element is defined as the reception level ratio R, then it can be expressed by the following equation.

Here, assuming L+: 4(H) and I>1.2.3(m), the diagram obtained by substituting and plotting each equation is the calculation 4 diagram.

The horizontal axis is the horizontal displacement tX of the magnetic field detection element.

As is clear from the figure, when the distance between the magnetic field generating cable and the construction plan line on the ground surface is constant (L = 4"), the reception becomes poor due to variations in depth (1, 2, 3 inches). It can be seen that the value of R is greatly affected.

Similarly, it will be understood that even if the depth is kept constant and the distance between the construction plan line and the magnetic field generating cable on the ground surface is changed, the reception level ratio will vary.

Therefore, if we investigate the correlation between the separation distance and depth and find the separation distance that cancels out the influence of depth, we can obtain the true horizontal displacement without making any correction for depth changes based on the reception level ratio of the magnetic field detection element. 8 However, the point to keep in mind here is that although the above illustrated example was based on various assumptions, a schematic D relational expression was obtained, but in general, Since the number, arrangement, orientation, etc. of the magnetic field detection elements to be installed are determined by the design goals of the position measurement system, the relationship between the depth and separation distance described above will change from time to time. The reason is that there is no fixed relationship between them.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a side sectional view of this embodiment, and FIG. 2 is a plan view of the same as seen from the ground surface.

In the diagram, 1 is on the ground surface, 2 is the starting shaft, 3 is the arrival technique,
Reference numeral 5 indicates an underground excavation exploration planned line, and 7 similarly indicates an excavation construction planned line on the ground surface, and the underground excavator 4 starts excavation from the starting shaft 2, and excavates along the planned line to reach the planned line. Reach Tatewaza 3.

In this embodiment, as shown in the figure, the excavation plan line excavates from the starting shaft 2 while gradually increasing the depth at a constant rate, and after reaching a predetermined depth, proceeds parallel to the ground surface, and then continues to the predetermined position. The plan is to advance the distance and increase the depth by 7 at a constant rate from the top until reaching Tatewaza 3. Construction plan line 7 on ground surface 1
is a straight line.

Here, in this embodiment, the reception level ratio R of the magnetic field detection element installed in the underground excavator 4 is determined by the magnetic field generation relative to the depth and the construction plan line on the ground surface for the same horizontal displacement amount of the magnetic field detection element. There is an inversely proportional relationship between the cable laying interval l and the top layer.

Therefore, the magnetic field generating cables 6 sandwich the construction planned line 7 on the ground surface 1, and initially the interval increases at a constant rate from the starting shaft 2 to the arrival vertical shaft 3 in response to the depth change of the excavation depth planned line 5. The distance between the point where the excavation depth is the deepest and the point where the same depth begins to decrease is set at equal intervals, and from then on, the loop shape is formed with a reciprocating line so that it narrows at the same rate as the depth change until reaching the third step. will be laid down.

By laying the magnetic field generating cable 6 in this way, the cable 6
When an alternating current is supplied to the magnetic field generating cable 6, a concentric magnetic field 8 is generated at the center of each reciprocating line, and this magnetic field is detected by a plurality of magnetic field detection elements equipped on the underground excavator 4. . The magnetic field detected by each magnetic field detection element is input to an arithmetic controller (not shown), and is compared and calculated in the arithmetic controller to determine the reception level ratio R. This reception level ratio R is compared with a preset reception level ratio to measure the amount of displacement of the horizontal position of the magnetic field detection element, that is, the underground excavator 4, and if there is a change, the position is corrected. A command is issued. At this time, the amount of variation in the horizontal position is determined by taking into consideration the depth change of the underground excavator 4 in advance, and setting the installation interval between the magnetic field generating cable 6 and the construction planned line on the ground surface in order to cancel the effect. Therefore, there is no effect of depth on the reception level ratio, and therefore, there is no need to perform correction based on depth when calculating the reception level ratio, and the value as it is can be converted into the amount of horizontal position displacement. will be used.

In the illustrated embodiment, the reception ratio of the magnetic field detection element is
We have described the case where there is a proportional relationship in the direction between the depth of the underground excavator and the spacing between the magnetic field generating cables on the ground surface, which cancels out their effects, but the relationship between the two is not always uniform. Since it changes depending on the number, arrangement, orientation, etc. of the magnetic field detection elements installed in the underground excavator 4, it is necessary to take these into consideration and understand their characteristics and correlation in advance, and then use them at the actual construction site. Immediate response 1. It is necessary to make a final copy of the drafting letter for the magnetic field generation cable (no changes to the content).

(Effects of the invention) The detailed VCM9 Mei 1. According to the present invention, the influence of the depth of the reception characteristics of the magnetic field detection element in the underground excavator is canceled out, the installation interval between the magnetic field generation cable and the construction planned line on the ground surface is set, and the magnetic field generation cable is Since the value detected by the magnetic field detection element can be directly converted into the amount of displacement in the horizontal position, there is no need for complicated correction calculations, and therefore the position measurement circuit in the arithmetic controller can be Not only can the results be easily determined, but the reliability of the results can also be further increased.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the ground showing the installation state of the magnetic field generating cable for position measurement of an underground excavator according to an embodiment of the present invention, Fig. 2 is a plan view of the same ground surface, and Fig. 3 shows the magnetic field generating cable and the ground. FIG. 4 is a schematic diagram showing the positional relationship of the magnetic field detection elements inside the underground excavator, and FIG. 4 is a diagram showing the influence of the magnetic field reception level due to changes in the depth of the underground excavator. Explanation of the main parts of the diagram 4. Underground excavator 5. Excavation depth planning line 6.
Magnetic field generation cable D...Depth! ... Construction plan line on the ground surface and installation interval (distance) of the magnetic field generation cable

Claims (1)

[Claims] A reciprocating line of a magnetic field generation cable is laid on the ground surface to generate a magnetic field, and the magnetic field is received by a magnetic field detection element inside the underground excavator. A position of an underground excavator characterized by laying a reciprocating line of a magnetic field generating cable on both sides of the intermediate excavator's planned construction line at a distance corresponding to the planned construction depth of the underground excavator. How to lay the magnetic field generation cable for measurement.