JPH0326729B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for measuring the amount of ground subsidence in soft ground improvement work and the like.

(Conventional technology) Conventionally, in the improvement work of soft clay ground using the paper drain construction method, etc., paper drain materials, etc. are driven into the improved ground, and then a loading embankment is carried out in the improved area, and the soft clay is poured through the paper drain. The pore water in the ground was drained, and the subsidence of the improved layer due to this drainage was continuously measured, and the completion of the improvement work was determined when the amount of subsidence reached the target value.

In order to measure the amount of ground subsidence, holes are drilled at appropriate locations in the improved area, a screw settling plate, etc. is buried, and the subsidence of this settling plate is measured at regular intervals using a leveling instrument. was measuring.

(Problem to be Solved by the Invention) However, this type of method for measuring the amount of ground subsidence requires a large number of borings, which not only requires considerable time and expense, but also requires a leveling survey to measure the amount of subsidence. Because it is a manual process, it is not something that anyone can easily do, and it is difficult to automate.

The present invention has been made with attention to these points, and by eliminating the need for boring for burying screw sink plates, it significantly reduces the time and cost required for boring, and allows anyone to easily perform measurements. The purpose of this project is to provide a method for measuring the amount of ground subsidence that can be automated.

(Means for Solving the Problems) The means of the present invention for solving the above-mentioned problems is based on a method for measuring the amount of ground subsidence and a method for measuring the amount of ground subsidence in soft ground improvement work, etc. is made of a flexible non-magnetic material that bends appropriately as the ground on which it is cast sinks, and magnetic markers, which are energized by electricity, are arranged and fixed at predetermined intervals on this long member. Then, the long member is driven into the improved ground by a drain material driving machine, and a measuring tube made of a non-magnetic material is driven in parallel to the long member in the vicinity of the long member. , a magnetic detector that detects the magnetic field generated by the magnetic marker is suspended in this measurement tube, and the magnetic field of the magnetic marker that is successively energized by an external power source is measured by the magnetic detector, and the measured value indicates a maximum value. A method for measuring the amount of ground subsidence, characterized by measuring the amount of ground subsidence based on each hanging depth of a magnetic detector.

(Function) In the method for measuring the amount of ground subsidence of the present invention configured as described above, a highly flexible long member on which magnetic detectors are fixedly arranged at predetermined intervals is cast by a drain material casting machine. By doing so, it is possible to eliminate the need for boring for burying screw settlement plates, etc., making it possible to significantly reduce the time and cost required for this boring work, and to measure the amount of settlement according to the degree of consolidation of the improved ground. This is achieved by sequentially measuring the maximum value of the magnetic field from a magnetic marker on a long member that bends with a magnetic detector suspended inside the measurement tube.This method not only makes it easy for anyone to perform measurement tasks, but also automates the work. It also made it possible.

(Example) Next, an example of implementation of the present invention will be described with reference to the drawings. The drawings are explanatory diagrams for explaining one embodiment of the method for measuring the amount of ground subsidence according to the present invention, with Fig. 1 showing the state immediately after pouring, and Fig. 2 showing the state after a predetermined period of time has elapsed. It is something.

In the drawing, 1 is a long member, which is a belt-shaped drain material used in normal ground improvement work.
For example, it may be made of paper drain material made of paper, chemical drain material made of synthetic resin and chemical fiber non-woven fabric, or other drain material itself with a plastic core, or it may be made of a highly flexible band-shaped non-magnetic material. As the improved ground 2 is consolidated, it bends appropriately.
Reference numeral 3 denotes a magnetic marker fixedly arranged at each of measurement points set at a predetermined interval on this elongated member 1, and is constituted by, for example, an electromagnet as a magnetic field generating means, and 4 is a magnetic marker fixedly arranged at each measurement point set at a predetermined interval. This is a cable that supplies current from the power supply 5 to the power supply 5.

Further, reference numeral 6 denotes a measuring tube, which is constructed of a non-magnetic pipe such as a hard vinyl chloride pipe or a stainless steel pipe. Reference numeral 7 denotes a magnetic detector for detecting the magnetic field generated by the magnetic marker 3. For example, a magnetic sensor using a ring core flux gate method is used for detecting a minute magnetic field. This magnetic detector 7 is connected to the measuring tube 6 by means of a hanging wire 8.
It is slidably suspended inside. A display section 9 displays the detection results of the magnetic detector 7, and is connected to the magnetic detector 7 via a cable 10. Further, reference numeral 11 is an imaginary line indicating a reference level for measuring the amount of ground subsidence.

Next, the measurement procedure will be explained.

First, N measurement points are set on the elongated member 1 at predetermined intervals, and a magnetic marker 3 is fixedly arranged at each of the measurement points. The elongated member 1 to which the magnetic marker 3 is attached is placed on improved ground 2 such as soft clay ground using a drain material placing machine in the same way as paper drain material.
It will be poured inside. At this time, the cables 4 from each magnetic marker 3 are extended from the upper end of the elongated member 1 to the ground, and are connected to a power source 5 as necessary. Next, the measuring tube 5 is placed close to the elongated member 1 and parallel to the elongated member 1. At this time, the distance between the measuring tube 5 and the long member 1 is
Good results were obtained when the length was 40 cm or less. FIG. 1 shows the state immediately after being cast in this manner.

Next, the cable 4 connected to the uppermost magnetic marker 3 is connected to a power source 5 and energized. As a result, the uppermost magnetic marker 3 is excited and generates a predetermined magnetic field around it. Here hanging wire 8
While lowering the magnetic detector 7 by lowering the magnetic detector 7, the magnetic field is successively measured and the position where the measured value shows the maximum value is determined. At this time, each suspension depth of the magnetic detector 3 is also measured using a rotary encoder or the like (not shown). Based on the depth value indicating the maximum value at this time, a depth measurement value from the virtual line 11 indicating the reference level of the uppermost measurement point is obtained.

Hereinafter, the cable 4 from the magnetic detector 3 connected to the power source 5 is sequentially connected to the lower one, and the magnetic detector 7 is lowered, and the same measurement is performed at each measurement point to determine the depth of each measurement point. Measure.
As a result, an initial value of the depth of each measurement point is obtained.

The improved ground 2, on which a large number of paper drain materials and the like are placed and loaded with earth, is consolidated by draining pore water through the paper drains over time. As a result, the improved ground 2 sinks, and the cast long member 1 bends in the improved ground 2 according to the amount of the sinking. FIG. 2 shows the state after such a certain period of time has elapsed.

By bending the elongated member 1, the vertical distance between each measurement point is shortened. The depth of each measurement point from the virtual line 11 indicating the reference level is measured by sliding the magnetic detector 7 up and down inside the measurement tube 6, as in the case described above. In this case, since the measuring tube 6 is made of a pipe made of hard vinyl chloride, stainless steel, etc., as described above, it will not bend like the elongated member 1.

Hereinafter, the above-mentioned measurements are sequentially repeated every predetermined period of time, and the depth measurement value from the virtual line indicating the reference level of each measurement point at that time is compared with the initial value of each measurement point. When it is confirmed that the amount of subsidence of the improved ground has reached the target value, it is decided to end the improvement work.

Although the embodiments have been described in detail in accordance with the illustrated embodiments, it goes without saying that the present invention is not limited thereto.

In addition, the long members to which magnetic markers are fixed are not limited to belt-shaped members similar to paper drain materials, etc.;
It may be of any other shape, such as a cylindrical shape, as long as it has the flexibility to bend appropriately as it is consolidated. In that case, the shape of the mandrel of the drain material casting machine etc. needs to be changed accordingly. Furthermore, the elongated member is not necessarily cast separately from the measuring tube as in the previous embodiment, but the elongated member and the distal end of the measuring tube are connected with a separately prepared member, and then the drain is connected. They may also be cast simultaneously by a timber casting machine. In this case as well, the structure of the drain material placing machine needs to be changed accordingly, as described above.

(Effects of the Invention) The present invention is constructed as described above, and has a structure in which a flexible elongated member in which magnetic markers are arranged at predetermined intervals can be cast by a drain material casting machine. Boring for burying the screw plate can be eliminated, and the time and cost required for boring can be significantly reduced. Furthermore, the measurement process is extremely simple: detecting the maximum magnetic point of the magnetic marker while moving the magnetic detector up and down, and measuring the amount of ground subsidence based on the hanging depth of the magnetic detector at that time. Not only can anyone easily carry out measurement work, but the work can also be automated, providing excellent results. Furthermore, by forcibly exciting the magnetic marker at the measurement position with an external power supply to generate a magnetic field, it is possible to select and measure only the magnetic marker at the measurement position from among multiple magnetic markers. Accurate measurements can be made without magnetic interference from markers.

[Brief explanation of drawings]

The drawings are explanatory diagrams for explaining one embodiment of the method for measuring the amount of ground subsidence according to the present invention, with Fig. 1 showing the state immediately after pouring, and Fig. 2 showing the state after a predetermined period of time has elapsed. It is something. 1... Long member, 3... Magnetic marker, 6...
Measuring tube, 7...magnetic detector.

Claims (1)

[Claims] 1. In a method for measuring the amount of ground subsidence in soft ground improvement work, etc., a long member is formed of a non-magnetic material with flexibility to bend as appropriate according to the subsidence of the ground on which it is cast, and this long member is Magnetic markers that are energized by energizing the member are arranged and fixed at predetermined intervals, and the long member is driven into the improved ground by a drain material driving machine, and a measuring tube made of a non-magnetic material is installed. A magnetic detector that detects the magnetic field generated by the magnetic marker is suspended in the measurement tube, and the magnetic marker is successively energized by an external power source. A method for measuring the amount of ground subsidence, comprising: measuring a magnetic field with the magnetic detector; and measuring the amount of ground subsidence based on each hanging depth of the magnetic detector when the measured value shows a maximum value.