JPH03161610A - Pressure variable type water pouring device into boring pit - Google Patents

Abstract

PURPOSE:To measure section pressure accurately by combining a centrifugal pump, a return piping and a flow regulating valve, arbitrarily adjusting the flow rate of discharge and pressure and supplying an in-pit pressure adding section inserted into a boring pit. CONSTITUTION:A continuous discharge type centrifugal pump 10, a return piping 12 and flow regulating valves 16a, 16b are combined, and the flow rate of discharge and pressure to a water discharge piping 24 can be adjusted arbitrarily. Upper and lower pneumatic-packers 42a, 42b are installed and a hydraulic-pressure adding section is set, and an in-pit pressure adding section with a water impregnating pipe 44 opened to said adding section and pressure transducers 46a, 46b is provided. The in-pit pressure adding section is inserted into a boring pit 40, the discharge piping 24 is connected to the water pouring pipe 44, and fixed hydraulic pressure or required variable hydraulic pressure is supplied for a prolonged time. The pressure of the hydraulic-pressure adding section responding to the supply of fixed hydraulic pressure or required variable hydraulic pressure is measured by the pressure transducers 46a, 46b.

Description

Detailed Description of the Invention 1 2 [Industrial Application Field] The present invention relates to a device for injecting pressurized water into a borehole, and more particularly, to a device that can freely vary the pressure inside the hole when water enters and enters the borehole. It is something. This device can be used, for example, for permeability tests to investigate the flow of water in the ground. [Conventional technology] A sinusoidal test is a test for determining the permeability of rock. This is a technique in which pressurized water that changes in a sine wave is injected from a transmitting hole formed in the rock mass, and the response pressure is measured at the receiving hole.This technology assumes a rock mass model and calculates the hydraulic conductivity of cracks through analytical solutions. be. The test is being conducted at a radioactive waste geological disposal experimental site in Sweden. The above test shows a very small hydraulic conductivity (on average 1.
The target is rock formations (below 0 x 10cm/sec).In order to generate a sine wave-like water pressure change, the water injection device has an intermittent discharge system that uses the reciprocating motion of a piston to draw in water, compress it to a predetermined pressure, and send it out. [Problems to be Solved by the Invention] The conventional piston-cylinder type reciprocating pump has the advantage of relatively easy adjustment of changes in pressure. However, in the general civil engineering field, it is possible to test special rock masses with extremely low permeability coefficients.However, it is a problem in the general civil engineering field (e.g., V containing fractures: the water activity coefficient of the plate is l.OXIO- '~I.OXIO-'cm/sec), the amount of water that infiltrates increases, and a commensurate Norinda volume is required, so conventional equipment inevitably has to grow in size. Specifically, a cylinder capacity ID of several hundred liters, for example, may be required, which is impractical for this type of test equipment that is carried out outdoors and by moving from place to place. In addition, in the piston-cylinder method, the discharge capacity per stroke is fixed, so if the water infiltration into the ground is large, the pressurization time will naturally become shorter, resulting in the inconvenience of not being able to perform tests under the necessary conditions. Ru. The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to improve the permeability coefficient in general civil engineering fields (for example, tunnels, dam 1!E foundation rock, slopes, I5 foundations, rock around underground cavities, etc.). It has a large water supply capacity that is sufficient to handle large geological formations, can apply constant or arbitrarily variable pressure to the water supply over a long period of time, is relatively compact, and has excellent mobility. An object of the present invention is to provide a variable pressure water injection device into a borehole. [Means for Solving the Problems] In the present invention, a pump serves as a large capacity water supply source and at the same time has a variable pressure generation function. In other words, the present invention, which can solve the above-mentioned technical problems, uses a continuous discharge type pump, A return pipe that branches from the discharge side and returns to the suction side, and a fi installed in the return pipe.
This is a variable pressure water injection device into a borehole, which is equipped with an lffl control valve and a discharge pipe that guides pump discharge water into the borehole. In practice, it is preferable to install a $21 on-off valve and a flow meter in the discharge piping. In addition, a volute pump is preferable from the viewpoint of principle, structure, and operating performance. In the permeability test, an in-hole pressure applying section is inserted into the borehole. This device consists of upper and lower pasocars that are water-blocked to set the water pressure addition section, a water injection pipe that is located approximately in the center and opens only in the water pressure addition section, and a pressure that directly measures the pressure in the water pressure addition section. A transducer is provided, and the water inlet pipe is connected to a discharge pipe.

[Function] Firstly, as long as the pump is operated at the rated power with a constant water head condition, both the discharge water volume and the discharge pressure will be constant values. The discharge water volume and discharge pressure during rated power operation change as the discharge water volume increases when the discharge pressure is low, and their absolute values are determined by the formal performance of the pump. The amount of water that permeates into the stratum increases or decreases in proportion to the water pressure, but in the water seepage test, a freely changing pressure is applied to the inside of the cell, regardless of the relationship between the pump's discharge water volume and discharge pressure, and the water volume at that time is determined. It is necessary to know the change and pressure propagation velocity. In the present invention, the water discharged from the pump is branched into two directions, one of which is provided with a flow control valve, and returned to the suction side. The discharged water then passes through the on-off valve and reaches the borehole. When the on-off valve and the flow M control valve are opened, the resistance of the return water flow is reduced and the suction force of the pump is applied, so most of the discharged water circulates through the return piping pump, reducing the pressure in the borehole and the inflow. The amount of water used will be very small. On the other hand, if the flow rate control valve is completely closed, the return water volume is cut off, allowing the full pumping capacity to be applied to the hole. Therefore, by controlling the flow rate control valve between these, it is possible to freely adjust the water volume and pressure to match the geological conditions within the hole. However, in order to completely block the flow into the borehole side, close the on-off valve installed in the discharge pipe.
+7! -There is a point. Therefore, if you adjust the flow adjustment button t to obtain the pressure necessary for wiping, and open and close the pressure adjustment button t using the opening/closing intermediary in the required time cycle, then at a predetermined pressure, the pressure is proportional to the force. It can be added to the wave-like permanent change GrL of the current time cycle of the shear amount. Also, open the on-off valve and /AF! i Is the opening of the control valve controlled according to a predetermined program pattern? By adding water, it is possible to add water in various patterns (for example, sinusoidal) in which the pressure and volume change continuously. In the borehole, water Y [by setting an additional section, the pressure pattern of each insertion can be applied to a section of a predetermined limited depth and limited length. (2) Water is discharged from the opening of the sweat pipe.The pressure at that time (1) is detected by the pressure transducer → J.The reason for measuring the pressure in the water pressure application section in the hole is that the water While moving through the discharge piping and water injection pipe from the pressure generating part of the pipe to a predetermined section in the inside, resistance depending on the material of the pipe and the flow rate occurs, and the pressure loss due to this resistance causes the pressure generating part and the pressure adding device to This is because there is a pressure difference between the two.The pressure that is really needed to evaluate the permeability of a geological formation is the actual pressure that is applied inside the hole, and it can be accurately detected using a pressure transducer. It is also possible to control the pressure generating section on the ground so that this pressure detection value becomes a predetermined pressure fluctuation. [Embodiment] An embodiment of the variable pressure type water injection device according to the present invention is shown in Fig. 1. This device has a vortex pump 10 and a return pipe I2 that branches its discharge water into two directions and returns one to the suction side.There are four systems of return pipes I2, each with a manual control valve 14 and an automatic control valve. 16a, 16b, safety valve 18 is incorporated. Automatic control valve +62 is for large capacity, and automatic control valve 16b is for small capacity, both of which are controlled by a program controller. Reference numeral 20 indicates a water tank. Homaki pump 1O
is controlled by the pump control panel 22.

The other branched discharge water is guided into the boring rL by the discharge piping 24. The discharge piping 24 is provided with a pressure gauge 26, an accumulator 2B, a needle on-off valve 30, a flow rate measurement system 32, and a pressure gauge 34. The flow measurement system 32 has 4
Is there a system, each one? T magnetic flowmeter 36a.・・・． 36
d and manual switching j↑38a,...,38d. These electromagnetic flow meters 36a.・・・． Each 36d has a different capacity. An in-hole pressure applying section is inserted into the borehole 40. This is provided with an upper pneumatic tank car 423 and a lower pneumatic tank car 42b, and a water injection pipe 4 between them.
Make sure that there are 4 openings. The area separated by both pneumatic pumps and puff forces -422 and 42b is the area where the water pressure is applied by 4t. Within that section and below lower pneumatic packer 42b are respective pressure transducers 46a. 46b and program those signals.
Leads to controller and pressure indicator. The reference numeral 48 indicates a gas supply device for expanding the Pneumatic Ha7h-42a and 42b. In this example, a spiral pump is used. When performing a water permeability test by applying rectangular wave-like water M fluctuations at the maximum pressure of the pump, the control valves 14, 16a and 16b of the return piping are fully idle, and the on-off valve 30 is opened and closed, but the on-off valve 30 When it is closed, the pump discharge is completely suppressed during operation.

Therefore, even in that case, the Il
It is necessary to use a similar type of pump. We selected a volute pump from this point of view. However, other types of pumps may be used as long as the above conditions are met.

Automatic control valve 16a. Reference numeral 16b is used to continuously change the pressure and flow rate applied to the inside of the hole, and the opening degree is automatically adjusted according to a predetermined program while detecting the pressure with the pressure transducer 46a. Control the pressure applied to the At this time, the twenty-one-dollar on-off valve 30 is left open. Also, if there is a simple pressure fluctuation, the automatic control valve 16a. 16b (leave it completely idle), and check the pressure detected by the pressure transducer 46a while adjusting the manual control valve l.
You can also adjust the opening with 4. The reason why there are two I"IvJ control valves is that they can be used for cases where the pressure fluctuation width is large and when the added pressure is high and the fluctuation width is small. When adding rectangular wave-like pressure fluctuations, the manual control valve is used. After adjusting the pressure using l4, the needle on-off valve 30 is opened and closed using a signal from a timer, etc. At this time, a water hammer is used in which the pressure increases instantaneously in the front and rear regions of the on-off valve 30 due to rapid opening and closing. There is a possibility that this phenomenon will occur. This phenomenon is undesirable in terms of measurement and may cause damage to the device. Therefore, a 21-dollar type valve is used as the on-off valve 30, in which this phenomenon is unlikely to occur. However, Any valve with performance that prevents this phenomenon from occurring is sufficient, and is not limited to the 21-dollar type.The safety valve 18 and the accumulator 28 are also provided as a defense in the unlikely event that water hammer occurs.Accumulator 28 also has the function of absorbing fluctuations such as the pulsation of the pump 10 and smoothing out the amount of water discharged.The amount of water flowing into Satsunai varies from several ml to 3 ml depending on the geological condition.
0 0 ml, which changes significantly. It is impossible to measure this accurately with one flow meter, and in this embodiment, four fLffl meters 36a. ...,
I am using 36d. The selection of which flowmeter to use is determined based on the results of preliminary tests, and manual switching valves 38a.
..., switch the route at 38d. The pressurized water that has passed through the lffi meter is led to the hole pressure application section. Pressurized water is in upper pneumatic tank 7 bunker 4
2a and the lower pneumatic packer 42b, and a predetermined type of pressure fluctuation is applied to that section. The pressure transducer 46a detects the pressure applied to the water pressure application section. When applying continuous pressure changes to the interior, the pressure signal is fed to the program controller to enable highly accurate program control. The pressure transducer 46b measures the pressure in the hole below the lower pneumatic bunker 42b, and from this the water distribution situation in the lower pneumatic bunker 42b is known.
This can be useful for analyzing permeability results. Figure 2 shows a conceptual diagram of a water permeability test using the water injection device of the present invention. A transmitting hole 52 and a receiving hole 54 are drilled in the fissure rock 5150 that is the object of analysis. The crack is indicated by No. 71 5L. Generally, a plurality of receiving holes 54 are formed at different positions. Upper and lower pneumatic puff force in the transmission hole 52 -55a,
55b, a four-water transmission section 56 is set, and pressurized water is injected from the water injection gzss on the ground surface. Here, the reception hole 54 is divided into a plurality of reception sections by a large number of bunkers 59, and a pressure transducer 60 is provided in each reception section, and the detection signal is sent to a recording/analysis device 6.
Sent to 2. The signals detected by each pressure transducer 60 represent temporal changes in the received pressure, and the data is stored in the recording and analysis device i1f.
62 is analyzed. This method of simultaneously detecting response pressure in multiple receiving sections can reduce the number of tests performed in the same analysis target area, which can shorten test work time.
It also reduces the amount of water injected into the analysis target area, which has the advantage of minimizing changes in the rock mass due to increased water injection. [Effects of the Invention] As described above, the present invention improves the pump so that it becomes a large-capacity water supply source and has a variable pressure generation function, and guides the discharged water to a predetermined section in the borehole to suppress pressure fluctuations. Since it is an additional device, the amount of water can be increased and it can be used in ground with a high permeability coefficient. It is possible to apply a constant or variable pressure to the supply water over a long period of time, and the pressure can be changed in various ways. For this reason, it is extremely suitable as a device for groundwater surveys and permeability tests in the general civil engineering field, and since it uses a continuous discharge pump, it can be made compact in relation to the volume of water, and it has excellent portability to test sites. In addition, the in-hole pressure application section that guides pressurized water into the borehole tag of the formation and applies pressure can be made very small and thin, making it possible to concentrate pressurized water only in a predetermined section of the borehole, and to apply pressure to that section. Pressure can be measured accurately. 4. [．． ;! 1 is a system diagram showing an example of the variable pressure water injection device according to the present invention, and FIG. 2 is a conceptual diagram of a water permeability wiping test using the same.

Claims (1)

[Claims] 1. A continuous discharge type pump, a return pipe that branches from the discharge side and returns to the suction side, a flow rate control valve provided on the return pipe, and guides the pump discharge water into the borehole. A variable pressure water injection device into a borehole equipped with discharge piping. 2. The water injection device according to claim 1, wherein the discharge piping is provided with an on-off valve and a flow meter. 3. It has an in-hole pressure applying part that is inserted into the borehole, and the in-hole pressure applying part is located approximately in the center of the upper and lower packers that block water in order to set the water pressure adding section, and the in-hole pressure applying part is located approximately in the center and 3. The water injection device according to claim 1, comprising a water injection pipe that is open only in the addition section, and a pressure transducer that directly measures the pressure in the water pressure addition section, and wherein the water injection pipe is connected to a discharge pipe.