KR100687630B1 - Ground packer test apparatus measuring porewater pressure at the hole - Google Patents

Abstract

The present invention is to install a water pipe in the borehole during the field test to measure the permeability of the ground and to seal the upper end of the test section to force injection at a predetermined pressure and observe the flow rate, etc. to calculate the lumen value It relates to the hydraulic test, which measures the pore water pressure in the test section of the borehole along with the pressure of the water forcedly injected from the ground, so that the effective injection pressure, which is the basis for calculating the lugeon value, can be accurately set.

Through the present invention, it is possible to obtain the effect of improving the reliability of the ground pressure test, and through the improvement of the overall precision of the ground survey it is possible to contribute to the accurate design and construction of the related construction projects.

Hydraulic test, pressured aquifer, pore pressure gauge, effective injection pressure

Description

Ground packer test apparatus measuring porewater pressure at the hole}

1 is a conventional ground pressure test progress diagram

2 is a conventional ground pressure test situation diagram

3 is a conventional ground hydraulic pressure test situation performed on the aquifer aquifer

Figure 4 is a ground pressure test situation diagram performed on the aquifer aquifer using the present invention

5 is a perspective view of one embodiment of the present invention

FIG. 6 is a perspective view illustrating a partially cut coupler of the embodiment of FIG. 5. FIG.

<Code Description of Main Parts of Drawing>

11: Free Water Aquifer

12: bedrock

13: underwater aquifer

21: water pump

22: flow meter

23: ground hydraulic pressure gauge

24: valve

31: air pump

32: air hose

40: water supply pipe

41: packer

42: ground pipe

49: casing

50: pore water pressure gauge

51: signal line

52: output device

60: coupler

61: outlet

62: packing

63: screw cap

The present invention is to install a water pipe in the borehole during the field test to measure the permeability of the ground and to seal the upper end of the test section to force injection at a predetermined pressure and observe the flow rate, etc. to calculate the lumen value It relates to the hydraulic test, which measures the pore water pressure in the test section of the borehole along with the pressure of the water forcedly injected from the ground, so that the effective injection pressure, which is the basis for calculating the lugeon value, can be accurately set.

The lumen value indicates the amount of injection per liter of injection length in liters at the pressure of 10kg / ㎠, which is an important factor to determine the permeability characteristics of the ground with relatively low permeability, as well as the basic construction of various structures, roads and underground structures. It is used as basic data for design throughout the construction.

Most field tests for permeability of the ground are performed by forming boreholes at the test target points and observing the inflow or outflow of groundwater in the boreholes, as shown in FIG. 1. In this case, the inflow and outflow of water in the rock 12 is observed through forced injection of water using a pump and a water pipe 40 to shorten the test time.

The general ground hydraulic test procedure is as follows.

First, to form a borehole in the test point, in the case of free water aquifer 11, which is a soil layer, it is difficult to maintain the empty wall, as shown in Figure 1, it is possible to install a casing 49, and then to the ground water pump 21, flow meter ( 22), a ground water pressure gauge 23, a valve 24, an air pump 31, and the like are installed, and a main water pipe 40 in which a packer 41 is installed at the distal end is inserted into the borehole.

The packer 41 installed at the distal end of the main water pipe 40 is connected to the ground through the air pump 31 and the air hose 32, and the compressed air is applied and expanded as the air pump 31 operates to expand the borehole. The top of the test section of the phase will be sealed.

As shown in FIG. 2, when the expansion of the packer 41 is completed and the sealing of the test section is completed, forced injection of water is started by the water feed pump 21, and then the predetermined injection pressure is gradually changed according to the detailed test method. The test is carried out according to the procedure in.

The basic concept of the ground hydraulic test is to calculate the lumen value by measuring the flow rate per unit area when water is injected into the ground at a specific pressure in the test section.The basis of the lumen value calculation is to increase and decrease step by step. It can be represented by the injection pressure (P).

This effective injection pressure P is a water pressure applied by the main water pump 21, and the main water pressure P0 measured by the ground water pressure gauge 23, and as shown in FIG. The elevation difference (h1) of the midpoint of the section, the free surface in the borehole and the elevation difference (h2) of the midpoint of the test section are determined by the following equation.

P = P0 + γ (h1-h2-hL) / 10

Here, γ and hL are the unit weight of water (in kg / cm 3) and the head of loss in the water pipe 40, respectively, and the units of pressure and length are in kg / cm 2 and m, respectively.

That is, the effective injection pressure (P) can be said to represent the pressure of the water actually penetrating the test section, which may have a significant difference from the main water pressure (P0) applied by the water pump 21 according to the test conditions, For the test, careful observation of the water level in the borehole is required, as well as careful control of the pressure by adjusting the output of the main pump 21 or the valve 24.

However, as shown in FIG. 3, when the pressure-bearing aquifer 13 is formed in the test section, only the free water surface formed in the borehole cannot reflect the groundwater head in the actual test section. Serious problems arise in the setting of (P).

That is, in the case of the pressure-bearing aquifer 13 as shown in FIG. 3, the actual borehole head to be applied to the effective injection pressure P may be referred to as h2 + Δh, not h2. Ignoring this, the error of applying h2 in the same way as the general ground was made, resulting in a distance from the actual lumen value.

As a method for measuring the actual head of the aquifer aquifer (13) can be thought of a separate borehole, that is, a method of perforating the observation well (觀測 井) around the periphery, but not only can escape the corresponding aquifer aquifer (13) However, it can be said that there is little field applicability since it takes considerable time to reach steady state level for significant observations.

The present invention has been made in view of the above-described problems, and the pore water pressure measurement in the borehole followed by the pressurized water is carried out by installing a pore water pressure gauge at the lower end of the main water pipe separately from the ground water pressure gauge. By applying the above-mentioned pore water pressure to the effective injection pressure setting, it is fundamentally prevented that the effective injection pressure frequently occurring in the aquifered aquifer is prevented.

In addition, in consideration of the test convenience, a coupler for connecting the main water pipe and the ground pipe is constituted, and the coupler forms an outlet through which a signal line connecting the pore pressure gauge and the output device passes, and the outlet is formed through a packing and a screw cap. The watertightness of was secured.

The detailed configuration and principle of the present invention will be described with reference to the accompanying drawings.

First, FIG. 4 illustrates a situation in which the present invention is applied to the case where the aqueous aquifer 13 is included in the test section of the ground hydraulic test, and the pore pressure gauge 50 in the lower portion of the main pipe 40 has a pore water pressure test section. The pore water pressure is measured before pressurized water, and the pore water pressure is usually measured in the saturated state of the surrounding ground, that is, in the pores of the granules. The principle is that the water is in a full state, in the water pressure test to which the present invention is applied, the aquifer aquifer 13 is not only saturated at all times, but also the excavation of the borehole and the inflow of surrounding groundwater. The pore water pressure measurement is not unreasonable, but if water does not occupy the test section, it is necessary to fill the test section with water by applying an appropriate amount of water in a non-pressurized state.

The measured pore water pressure (Pv, in kg / cm 2) is applied to determine the effective injection pressure (P) through the following equation.

P = P0-Pv + γ (h1-hL) / 10

In this way, the pore water pressure between the ground injection pressure and the borehole test section is parallel, so that the error of applying the free water head in the borehole to the ground hydraulic test of the aquifer aquifer 13 is avoided.

FIG. 5 illustrates the water supply pipe 40 according to the present invention, and connects the water supply pipe 40 and the water supply pump 21 and the ground pipe 42 installed with various measuring instruments and valves 24 to be inserted into the borehole. A coupler (60) is formed, and the outlet port 61 passes through the coupler 60, as shown in FIG. 6, so that the signal line 51 connecting the pore pressure gauge 50 and the output device 52 can pass therethrough. By forming a), the installation of the pore water pressure gauge (50) can be made at the same time as the injection of the main water pipe (40).

Particularly, as can be seen from FIG. 6, a packing 62 is installed at an outlet 61 having a screw formed on an outer circumferential surface thereof, and a screw cap 63 is formed to be combined with the outlet 61 to compress the packing 62. Thus, the watertightness of the coupler 60 was secured.

On the other hand, the main water pipe 40 of the ground hydraulic test is a single packer 41 type and the main packer with a single packer 41 is installed at the tip as shown in the example shown from the bottom of the packer 41 to the borehole bottom A pair of packers 41 are installed in the water pipe 40 at a predetermined distance apart, and may be classified as a double packer 41 having a plurality of holes formed in the main water pipe 40 of the separation section. The system 50 is installed between both packers 41.

Eventually, the technical gist of the present invention is provided with a packer 41 installed at a lower portion of the water supply pipe 40 to be injected into the borehole, and a water injection pump 21 connected to the water supply pipe 40 and the ground pipe 42 to inject water. ), And a ground hydraulic test apparatus including an air pump (31) connected to the packer (41) and the air hose (32) to supply air, the pore pressure gauge (50) at the lower end of the main water pipe (40) Is installed, and the pore pressure gauge 50 is connected to the output device 52 on the ground, and measures the pore water pressure in the test section of the borehole. Correlation 42 and the water supply pipe 40 is connected through the coupler 60, the coupler 60 is formed with a lead inlet 61 through which a screw is formed on the outer peripheral surface and the signal line 51 passes, the outlet 61 In the borehole pore water pressure side type, characterized in that the packing 62 is inserted, the screw cap 63 for pressing the packing 62 is coupled It is a ground hydraulic test device.

Through the present invention, it is possible to obtain the effect of improving the reliability of the ground pressure test, and through the improvement of the overall precision of the ground survey it is possible to contribute to the accurate design and construction of the related construction projects.

Claims (2)

delete Packer 41 is installed in the lower portion of the water supply pipe 40 is injected into the borehole, and the water supply pump 21 is connected through the water supply pipe 40 and the ground pipe 42 to inject water, the packer 41 And an air pump (31) connected to the air hose (32) to supply air, wherein the pore water pressure gauge (50) is installed at the lower end of the main water pipe (40), and the pore water pressure gauge ( In the borehole pore water pressure side pressure ground pressure test device, characterized in that 50 is connected to the ground output device 52, the pore water pressure in the test section of the borehole, Ground pipe 42 and the water pipe 40 is connected through a coupler 60, The coupler 60 is formed with a lead outlet 61 through which a screw is formed on the outer circumferential surface and the signal line 51 passes; Outlet (61) is inserted into the packing 62, the screw cap (63) for compressing the packing 62 in the borehole pore-pressure side-by-side ground hydrostatic pressure test apparatus.

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