Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Earth stresses
Reexamination Certificate
2000-06-28
2003-03-11
Raevis, Robert (Department: 2856)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Earth stresses
C340S690000
Reexamination Certificate
active
06530284
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sensing unit for sensing geographical displacement such as the displacement of the ground, a snow accumulation section, an underground water level or the like, and a monitoring apparatus for monitoring a landslide, a snowslide or the like using the sensing units.
There has been a pressing need for the development of a system capable of predicting the occurrence of disaster, such as a landslide caused by a heavy rain or a snowslide in a snowy area.
One conventional means for sensing the softening of the ground is such as to sense whether any of the previously stretched wires on the ground have been broken by the movement of the ground. With this type of sensing unit, however, wires have to be stretched over a wide area, which needs not only a lot of time and labor but also has the difficulty in determining the place and direction in which the ground has been displaced, resulting in a problem that it is impossible to estimate the degree of displacement.
To overcome the problems, ground sensing units using various measuring instruments have recently developed. One of them is such as to estimate the displacement of the ground, the depth of the landslide surface, and the amount of slide by use of a servo inclinometer where a weight is supported horizontally by a case via springs, or by use of a pipe strain gauge.
In the case of a ground sensing unit using the servo inclinometer, pipes are put in the holes bored in the ground and servo inclinometers are inserted into the pipes stepwise in such a manner that they can be hoisted. As the servo inclinometers are hoisted, the tilt angles are measured automatically on the basis of the displacements of the springs. By measuring the side displacement, the displacement of the ground or a continuous underground wall, i.e., a landslide can be measured.
In the case of a ground sensing unit using a pipe strain gauge, a large number of vinyl chloride pipes are inserted vertically into holes bored in the ground, while being connected to one another with intermediate pipes. Strain gauges have been stuck to suitable portions of the pipes. The resulting assemblies are fixed in place by filling the space around them with sand. By measuring the amount of bending strain while changing the strain gauge on the vinyl chloride pipe from one depth to another, the magnitude and depth of a slide can be estimated.
Such ground sensing units, however, require a large number of measuring instruments to be installed in a place where a landslide collapse may take place. Therefore, the installation work needs a lot of time and labor. The ground sensing units installed in the different positions must be connected to each other with a power cable and a communication cable.
Because the ground sensing unit using a servo inclinometer needs a moving section, it requires a large space as a whole. In the case of the ground sensing unit using pipe strain gauges, vinyl chloride pipes must be inserted vertically, while being connected to each other with intermediate pipes, and the space around the pipes must be filled with sand. Therefore, it is difficult to install a large number of pipes over a wide area in a mountainous region.
Furthermore, in the case of the ground sensing unit using the servo inclinometer or pipe strain gauge, because the side displacement of and the amount of bending strain of the ground can be measured but the position of each ground sensing unit buried in the ground cannot be sensed, they cannot be measured when all the ground has been displaced.
With this backdrop, there have been demands for a monitoring apparatus which is easy to bury in the ground and can predict the occurrence of disaster, such as a mudslide in the ground or a snowslide in a snowy region, by use of sensing units capable of sensing the displacement exactly even when the whole of the ground or the snow accumulation section has been displaced, and for a sensing unit to be used in the apparatus.
Moreover, there has been demands for a ground monitoring apparatus which is capable of sensing the displacement of the ground, regardless of the places of installed sensing units, and of predicting the occurrence of disaster, such as a mudslide in the ground, and for a sensing unit to be used in the apparatus.
As a means of predicting the occurrence of disaster, such as a mudslide in the ground, there is an underground water level sensing unit which measures the penetrating water level of rainfall in, for example, a mountainous region or a slope area or measures the position of a water vein in the ground and the state of the infiltration from the water vein. An example of the configuration of such an underground water level sensing unit is shown in FIG.
1
.
In
FIG. 1
, numeral
21
indicates foundation concrete laid in the ground. In the foundation concrete
21
, a through hole that extends from the surface of the earth into the ground is made. Numeral
22
is a cylindrical member buried in the ground in such a manner that the member is inserted into the through hole in the foundation concrete
21
. The cylindrical member
22
can be adjusted so as to have a suitable length according to how deep the cylindrical member is buried. Holes that penetrate through the member are arranged in the direction of its axis.
Numeral
23
is a case placed on the foundation concrete
21
, with the cylindrical member
22
in the center of the case. In the upper part of the case
23
, a float driving unit
24
is provided. The float driving unit
24
holds a wire
26
in such a manner that the wire can move vertically in the cylindrical member
22
. A float
25
is attached to the tip of the wire
26
. The float driving unit
24
rolls up or down the wire
26
as the float
25
moves up or down according to the level of the water accumulated at the bottom of the cylindrical member
22
.
In the lower part of the case
23
, a measuring instrument
27
and a transmitter
29
are provided. The measuring instrument
27
measures the level of the water accumulated at the bottom of the cylindrical member
22
from the movement of the wire
26
rolled up or down by the float driving unit
24
. The transmitter
29
transmits the data measured at the measuring instrument
27
to a base station (not shown) via an output cable
28
laid in the ground.
In the underground water level sensing unit constructed as described above, when rainwater has permeated into the ground, the water passes through the holes arranged in the direction of the axis of the cylindrical member
22
and collects at the bottom of the cylindrical member
22
. The level of the water accumulated at the bottom of the cylindrical member
22
is measured by the measuring instrument
27
from the movement of the wire
26
rolled up or down according to the up-and-down movement of the float
25
.
Such an underground water level sensing unit, however, can measure only the water accumulated at the bottom of the cylindrical member
22
but cannot judge how much the water has come from how depths of the stratums.
In a landslide danger zone, such as a slope area, it is important to measure how much rainwater has permeated into the ground and judge whether the rainwater has reached a stratum that is liable to cause a landslide. According to the conventional float-type water level sensing unit, however, the water which has come from all of an upper stratum, an intermediate stratum and a lower stratum is accumulated at the bottom, so that it is impossible to judge how much the water has come from how depths of the stratums, which prevents effective prediction of a landslide.
The float-type water level sensing unit has another problem: when the cylindrical member
22
has been deformed and the float
25
has come into contact with the inner wall of the cylindrical member
22
, this prevents the float
25
from making up-and-down movement and makes it difficult to accurately measure the water level.
Moreover, in installation, a hole must be bored vertically with high accuracy so that the float
25
may no
Ikeda Takaaki
Oogawara Takashi
Tambo Eitarou
Lackenbach & Siegel LLP
Mitsui Bussan Plant & Project Corporation
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