JPH06294116A - Water permeability tester of base rock - Google Patents

Abstract

PURPOSE:To measure water permeability of a base rock, by enclosing a certain length along the logitudinal direction of a boring hole with a packer to set a test race and measure the pumped water volume and pressure combined with each other by driving a water pump. CONSTITUTION:A sonde within a hole, composed of a packer 2, a water pump 3, a pressure gauge 4, etc., is inserted in an existing boring hole 1. When it reaches a specified depth, the packer 2 is swollen to contact with pressure the wall of boring hole and close a testing range of depth and then the sonde is equipped. The pressure at a steady state is regarded as the initial pore water pressure of the testing range and the water pump is driven to set several stages of pumping pressure and to measure combined figures of pumping water volume and pressure. This measuring is carried out at a plurality of points of the same boring hole and also a plurality of different boring holes. And the entirely water permeability is evaluated. And further, evaporated gas is separated and the pumping actuation is kept normal by providing a gas chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rock permeability test apparatus used for investigating the water permeability characteristics of rock mass.

[0002]

2. Description of the Related Art In constructing a rock structure, it is often indispensable to grasp the permeability characteristics of the natural ground such as the permeability coefficient. Conventionally, the water permeability characteristics of rock mass have been evaluated mainly based on the results of the Lugeon test, which is classified as a water injection test among the water permeability tests that use boring holes. However, when the bedrock structure is an underground cavity such as a tunnel or underground power plant, it is considered that the depressurization-pumping type permeability test faithfully reflects the actual water flow rather than the pressurization-water injection type permeability test. .

The pumping type water permeability test is a test frequently used for aquifers of soil ground, and the groundwater level of the surrounding ground is lowered by pumping water from the pumping well, and a plurality of observation wells provided around the pumping well. This is a method to obtain the hydraulic characteristics of the ground by observing the change in groundwater level over time.

In the case of bedrock, the groundwater flow path is mainly through the joints of rock bed and discontinuous surfaces such as crush zones, so that the water permeability is largely inhomogeneous and the longitudinal direction of the borehole. Shows a non-uniform distribution along. Therefore, it is not possible to directly apply the pumping type permeability test for soil to the permeability test of rock.

Most of the boreholes are bored vertically from the surface of the earth. Therefore, if a pumping pump is installed on the surface of the earth, if the groundwater level becomes 10 m or more lower than the surface of the earth, further pumping is not possible. Can't do.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended for rock mass and can be used even when the groundwater level is deep, and the water permeability of rock mass having heterogeneity is measured along the length direction of the boring hole. An object of the present invention is to provide a rock permeation test device that can be used. Further, the rock permeability test apparatus of the present invention enables setting of an arbitrary test pressure in an arbitrary section in the boring hole.

[0007]

According to a first aspect of the present invention, a packer for closing a test section is provided in a boring hole drilled in rock, a pressure gauge is provided in the test section, and pumping is performed near the test section. A rock permeability test apparatus provided with a pump and a pressure measuring device, a pumping amount measuring device, and a pump control device on the ground surface. The second invention is for blocking a test section in a borehole drilled in the rock. A packer is provided, a gas chamber communicating with the test section is provided near the test section, a pump is provided above the gas chamber, and a pressure gauge is arranged in the test section.
Place a differential pressure gauge (measure the water level in the gas chamber) in the gas chamber,
Equipped with a gas supply and exhaust pipe in the gas chamber, pressure measuring equipment, pumping volume measuring equipment, water level measuring equipment, pump control equipment,
And a rock permeation test apparatus provided with an air supply / exhaust device, wherein the third invention further comprises a water injection pump with a flow rate measuring device for injecting water into the gas chamber or the test section on the ground surface. It is the bedrock water permeability test device described in 2.

The first gist of the first invention is characterized by inhomogeneity by closing a fixed length along the length direction of the boring hole with a packer and using the closed section as a test section. With respect to the rock mass, it is possible to accurately grasp the permeability of each test section along the length of the boring hole.By separating this test section with a packer, conventional soil soil is targeted. As a result, the pumping type water permeability test that has been carried out will be applicable to rock.

A second important point of the first invention is that a pump having a relatively small diameter is installed near the test section in the boring hole, so that a pumping type water permeability test can be performed even if the groundwater level is low. Will be able to.

The gist of the second invention is that, in addition to the first invention, a gas chamber communicating with the test section is provided. By providing the gas chamber, the turbulence of the flow rate (pulsation etc.) caused by the operation of the pump is prevented. By reducing the pressure, the pressure or flow rate in the test section can be easily adjusted.

The gist of the third invention is that a pressurizing / water-injecting function by a water injection pump is added to the first and second inventions.
As a result, the pressure in the test section can be set arbitrarily, and it can be used as it is as a water injection test device without operating the pump.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of the first invention. The installation and operation of the first invention will be described below.

(1) The packer 2, the pumping pump 3, the pressure gauge 4, and the accompanying conductor and conduit in the hole are inserted into the existing boring hole 1 to reach a predetermined depth. The packer 2 is inflated and pressed against the wall of the boring hole to close the test section, and a sonde is installed.

(2) Wait for the pressure in the test section to reach a steady state. The pressure at the steady state is the initial pore water pressure in the test section.

(3) The pumping pump 3 is operated and the pumping pressure (initial pore water pressure-test section pressure) is set in several stages,
The combination of the pumping amount and pumping pressure at that time is measured.

(4) The operations of (1), (2), and (3) are performed for a plurality of places in the same boring hole and for a plurality of boring holes to measure the water permeability characteristics, and evaluate the overall water permeability characteristics.

FIG. 1 shows an example in which the test section is closed by two packers 2. However, since the hole bottom is closed at the deepest part of the boring hole 1, the packer 2 is located at the upper part.
Only one is enough.

FIG. 2 is a vertical sectional view of the second invention. In the second invention, in addition to the devices of the first invention, a gas chamber 10 communicating with the test section is provided, and accompanying it, a differential pressure gauge 11, a supply / exhaust device 7, a water level measuring device 8, a pump pump control. The device 9 is additionally installed. The functions and operations added in the second invention will be described below. When the pump 3 is operated, the pressure in the test section drops, and the gas that had been dissolved in the groundwater up to that point is vaporized.
Sucks gas together with the groundwater, which hinders the operation of the pump 3. In such a case, the exact relationship between the pressure in the test section and the pumping rate cannot be grasped. At this time, when the gas chamber 10 is provided, the vaporized gas is immediately separated from the groundwater and is not sucked into the pump 3, so that the pump 3 is kept operating normally.

Further, when it is desired to set the pressure in the test section to a predetermined value, the gas is allowed to flow into and out of the gas chamber 10 from the air supply / exhaust device 7 through a float type check valve 12 (a valve that allows gas to pass but not liquid). Let At this time, the gas chamber 10
The water level inside is measured by the water level measuring device 8 through the differential pressure gauge 11, and the result is transmitted to the pumping pump control device 9 to control the pumping amount of the pumping pump 3 to keep the groundwater level in the gas chamber 10 constant. To do. By this operation, it is possible to easily measure the relationship with the pumping rate at a predetermined test section pressure and the temporal change of the pumping rate under a predetermined test section pressure. Set the test zone pressure to several levels and perform the above operation.

FIG. 3 is a longitudinal sectional view of an example of the third invention,
In addition to the devices of the first aspect of the invention, a water injection pump 13 with a flow rate measuring device is provided, and a conduit, a check valve 14 and the like are additionally installed. In this example, in addition to the operation of the first invention, the pressure in the test section can be arbitrarily set. FIG. 3 shows an example in which the water injection pump 13 with the flow rate measuring device is provided in addition to the devices of the first invention, but also in the case where the water injection pump 13 with the flow rate measuring device is provided in addition to the devices of the second invention. Similarly, it is possible to set an arbitrary test section pressure by a method different from the second invention. Second
When the water injection pump 13 is additionally installed in the invention, the end of the conduit of the water injection pump 13 and the check valve 14 are installed in the gas chamber 10.
It is placed in the groundwater inside.

[0022]

INDUSTRIAL APPLICABILITY The apparatus of the present invention can be used even when the groundwater level is deep, and can measure the water permeability of rocks having heterogeneity along the length of the borehole. Disturbance of measured value due to pulsation of pumping pump can be eliminated.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view in which the device of the first invention is installed.

FIG. 2 is a vertical cross-sectional view in which the device of the second invention is installed.

FIG. 3 is a vertical cross-sectional view in which the device of the third invention is installed.

[Explanation of symbols]

1 ・ ・ Boring hole, 2 ・ ・ Packer, 3 ・ ・ Pumping pump, 4 ・ ・ Pressure gauge, 5 ・ ・ Pressure measuring device, 6 ・ ・ Pumping amount measuring device, 7 ・ ・ Supply / exhaust device, 8 ・ ・ Water level measurement Equipment, 9
..Pump control device, 10 ... Gas chamber, 11 ... Differential pressure gauge, 12 ... Float type check valve, 13 ... Water injection pump with flow rate measuring device, 14 ...

Claims (3)

[Claims] 1. A packer for blocking a test section is provided in a boring hole drilled in rock, a pressure gauge is provided in the test section, a pump is provided in the vicinity of the test section, a pressure measuring device and pumping are provided on the surface of the ground. Rock permeability tester equipped with volume measuring equipment and pump control equipment 2. A packer for closing the test section is provided in a boring hole drilled in rock, a gas chamber communicating with the test section is provided above the test section, and a pumping pump is provided in the vicinity of the gas chamber. A pressure gauge is placed inside, a differential pressure gauge (measuring the water level in the gas chamber) is placed inside the gas chamber, a gas supply / exhaust pipe is provided in the gas chamber, and a pressure measuring device, a pumping amount measuring device, and a water level measuring device on the ground surface. Rock permeation test equipment equipped with equipment, pump control equipment, and air supply / exhaust equipment 3. The rock permeation test apparatus according to claim 1 or 2, further comprising a water injection pump with a flow rate measuring device for injecting water into the gas chamber or the test section on the surface of the earth.