JP6218079B2 - In-hole loading test equipment - Google Patents

Description

  The present invention relates to an in-hole loading test apparatus for grasping mechanical characteristics such as a ground reaction force coefficient (K value).

When performing the basic design of a structure, it is important to accurately grasp in advance the mechanical characteristics such as the ground reaction force coefficient (K value), deformation coefficient (E value), and ultimate support force.
For this reason, in order to investigate the mechanical characteristics of the ground, the method of in-hole loading test has been standardized in the Japan Geotechnical Society Standard (JGS).

  This in-hole loading test is a kind of in-situ test, in which an elastic tube called a sonde is placed in a hole formed in the ground by boring, and liquid pressure is applied to the sonde to expand it, and at that time From the relationship between the pressure and the displacement of the hole wall, the mechanical properties of the ground such as the ground deformation coefficient, ground reaction force coefficient, yield pressure, ultimate pressure, and static earth pressure are obtained.

FIG. 4 shows a conventional test apparatus used for the in-hole loading test.
As shown in FIG. 4, the rubber sonde 1 disposed in the borehole of the ground, the pressure water supply means 2 for supplying pressure water into the sonde 1, and the cell pressure for detecting the pressure in the sonde 1 This is generally composed of three.

  Here, the pressure water supply means 2 includes a tank 4 for storing water, and a nitrogen gas cylinder 5 for supplying pressurized nitrogen gas to the upper portion of the tank 4, and the regulator 6 is connected to the nitrogen gas cylinder 5. The pressurized nitrogen gas is supplied into the tank 4 through the pressure, and the pressurized water thus supplied is supplied into the sonde 1.

According to the in-hole loading test apparatus, the change in the pressure in the sonde 1 is measured by the cell pressure gauge 3, and the amount of displacement of the inner wall of the hole is calculated by measuring the water level change ΔH in the tank. Using the relationship between the pressure and the displacement amount, the ground deformation coefficient (E value) and the horizontal ground reaction force coefficient (K value) can be obtained.
Patent Document 1 below also discloses this type of in-hole loading test apparatus.

JP 2002-24830 A

  By the way, in the conventional in-hole loading test apparatus shown in FIG. 4, it is necessary to supply approximately 3 Mpa of pressure water into the sonde 1, although it varies depending on the soil soil. For this reason, a nitrogen gas cylinder having a nitrogen gas pressure of about 15 MPa is usually used as the nitrogen gas cylinder 5, and the tank 4, the pipe 7a from the nitrogen gas cylinder 5 to the tank 4, the pipe 7b from the tank 4 to the sonde 1, and the cell from the sonde 1 As the pipe 7c to the pressure gauge 3, one having a pressure resistance of about 3Mpa is used.

  For this reason, the tank 4 corresponds to a high-pressure gas production facility stipulated in the High-Pressure Gas Safety Law, and the nitrogen gas cylinder 5 and the pipes 7a, 7b, and 7c must be handled in accordance with various laws and regulations. Since it is necessary to submit a proper pressure-proof inspection and various reports, there is a problem in that work based on many laws and regulations occurs accompanying actual construction.

  In addition, since the tank 4 and the nitrogen gas cylinder 5 which are pressure-resistant containers each have a weight of 20 to 40 kg, there is a problem that a lot of labor is required for transportation, installation and dismantling to the test location. Moreover, since nitrogen gas which is a compressive fluid is used as a pressurizing source of pressure water, there is also a problem that it is difficult to stabilize the internal pressure of the sonde 1.

  The present invention has been made in view of the above circumstances, and it is possible to perform a hole loading test with high accuracy by stably holding the internal pressure of the sonde by a light and simple device that does not correspond to a high-pressure gas production facility. It is an object of the present invention to provide an in-hole loading test apparatus that can be used.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a sonde disposed in a test hole formed in the ground, a pressurized liquid supply means for supplying a pressurized liquid into the sonde, and the above In the in-hole loading test apparatus comprising a pressure detecting means for detecting the pressure in the sonde and a measuring means for detecting the displacement of the inner wall of the test hole by the sonde, the pressurized liquid supply means has a stroke of a piston rod. There the same two double acting pump, a tank for supplying liquid to the cylinder chambers of the front and rear of these double-acting pump piston, a motor for the piston rod of a double acting pump reciprocating, the double the pressurized liquid from each cylinder chamber of the dynamic pump will and a discharge side pipe for introducing into said sonde, and two of said piston rod, one of the piston than the other of the piston 1 In four cycles delayed position with being connected to said motor so as to perform the reciprocating, the measuring means may be installed in the tank is a water level sensor for detecting a liquid level of the liquid Is.

According to the first aspect of the present invention, the double-acting pump serving as the pressure generating source for the sonde pressurization does not correspond to the high-pressure gas production facility defined in the High-Pressure Gas Safety Law. Periodic inspections based on various laws such as the Gas Safety Act and submission of various reports are no longer necessary. As a result, it is possible to omit many procedures and the like accompanying the actual construction, and to improve the efficiency of the work.

In addition, since a heavy pressure-resistant tank, a high-pressure gas cylinder, or the like is not required, the entire apparatus can be significantly reduced in weight, and transportation, installation, and disassembly work are facilitated.
Further, in addition to alternately supplying liquid pressurized in each cylinder chamber before and after the piston of the double-acting pump to the sonde, the liquid ignores compressibility compared with conventional nitrogen gas. Therefore, the internal pressure of the sonde can be stably controlled.

Further, since the pressurized liquid is directly supplied into the sonde from the double-action pump, the volume change amount of the liquid in the tank supplied to the double-action pump is always equal to the volume change amount of the sonde. For this reason, the volume change amount of the sonde can be accurately grasped by a simple water level sensor installed in the tank without using an expensive flowmeter compatible with high accuracy and high pressure.
The

Moreover, because it is moved back and forth by the motor piston rod of a double acting pump, it is possible to further labor saving. In this case, two double-acting pumps are provided, and the two piston rods are connected by the motor so that the reciprocating motion is performed at a position where one piston is delayed by a quarter cycle from the other piston . Therefore, the pressure fluctuation of the pressurized liquid supplied to the sonde can be reduced.

It is a schematic block diagram which shows 1st Embodiment of the in-hole loading test apparatus which concerns on this invention. It is a schematic block diagram which shows the 2nd Embodiment of this invention. The result of an Example is shown, It is a graph which shows the change of the pressurization elapsed time and the pressure in a sonde by the 1st and 2nd embodiment and a comparative example. It is a schematic block diagram which shows the conventional in-hole loading test apparatus.

(First embodiment)
FIG. 1 shows a first embodiment of an in-hole loading test apparatus according to the present invention. The in-hole loading test apparatus includes a sonde 10 disposed in a test hole formed in the ground, and the sonde 10. A manual double-action pump (pressurized liquid supply means) 11 for supplying pressurized water therein and a tank 12 for supplying water to the double-action pump 11 are schematically configured.

  The sonde 10 is an elastic tube made of rubber and is a general-purpose one used in a general in-hole loading test apparatus. A pressure gauge (pressure detection means) 13 for detecting the internal pressure is attached to the upper end of the sonde 10.

  The double-acting pump 11 is provided with a piston 15 movably provided in the cylinder 14 and a piston rod 16 extending outside the cylinder 14 is connected to a manual pressurizing handle 17 so as to be added. The piston 15 is reciprocated in the cylinder 14 by swinging the pressure handle 17 around the fulcrum 17a.

  Supply lines 18a and 18b from the tank 12 are connected to the suction ports of the front and rear cylinder chambers 14a and 14b with the piston 15 of the double-acting pump 11 interposed therebetween, respectively. Here, check valves 19 a and 19 b that allow only a flow from the tank 12 to the double-acting pump 11 and a shutoff valve 20 are interposed in the supply lines 18 a and 18 b.

  The tank 12 is a container having a constant cross-sectional area, in which water W is stored, and the liquid level is at atmospheric pressure. Further, a magnetostrictive water level sensor (measuring means) 21 is provided in the tank 12, and an indicator 21a of the magnetostrictive water level sensor 21 is disposed on the upper lid 12a.

  On the other hand, discharge side pipes 22a and 22b are connected to the discharge ports of the cylinder chambers 14a and 14b of the double-acting pump 11, respectively, and a pressurized water supply pipe 22 joined by the discharge side pipes 22a and 22b is connected to the inside of the sonde 10. Has been introduced. Here, the discharge side pipes 22 a and 22 b are provided with check valves 23 a and 23 b that allow only the flow from the double-acting pump 11 to the sonde 10, and the supply pipe 22 is provided with a shut-off valve 24. Yes.

  Furthermore, a pressure gauge 25 for measuring the pressure of pressurized water by the double-acting pump 11 is attached to the supply pipe 22 via an accumulator 26, and a relief valve when the internal pressure of the supply pipe 22 exceeds a certain pressure. A return line 28 is provided for returning the pressurized water to the tank 12 by operating 27. In the figure, reference numeral 29 denotes a recovery line in which a shutoff valve 29a for returning the water in the sonde 10 to the tank 12 is interposed.

  In the in-hole loading test apparatus having the above-described configuration, first, the shutoff valve 29a is closed, the shutoff valves 20 and 24 are opened, and the pressurizing handle 17 is swinged to reciprocate the piston 15. Then, due to the reciprocating motion of the piston 15, the inside of the cylinder chambers 14a, 14b alternately becomes negative pressure, the water in the tank 12 flows from the check valves 18a, 18b, and then pressurized and discharged on the discharge side pipes 22a, 22b. Is sent to the supply pipe 22 through the check valves 23 a and 23 b and supplied into the sonde 10.

Thereby, the rubber | gum of the sonde 10 is pressurized and expansion | swelling is started. Next, the pressure handle 17 is operated to gradually increase the pressure in the sonde 10 to a predetermined pressure, and at the same time, the water level sensor 21 records the water level in the tank 12.
From the relationship between the change in the internal pressure of the sonde 10 thus obtained and the amount of water supplied, the ground deformation coefficient (E value) and the horizontal ground reaction force coefficient (K value) are obtained.

  As described above, according to the in-hole loading test apparatus configured as described above, the double-acting pump 11 that does not correspond to the high-pressure gas production facility defined in the High-Pressure Gas Safety Law is used as a pressure generation source for pressurizing the sonde 10. As a result, regular inspections based on various laws and regulations such as the High Pressure Gas Safety Law and submission of various notifications are no longer necessary, thus eliminating many procedures associated with actual construction. Work efficiency can be improved.

  In addition, since there is no need for a heavy pressure-resistant tank or high-pressure gas cylinder, the overall device can be significantly reduced in weight, making it easy to carry, install and dismantle, as well as manual double-acting Since the pump 11 is used, coupled with the light weight, for example, it is possible to easily cope with the investigation of the ground in a place where it is difficult to secure a power source.

  Furthermore, in the in-hole loading test apparatus, water, which is an incompressible fluid supplied from the tank 12, is pressurized by the double-acting pump 11 and supplied into the sonde 10, so that the internal pressure of the sonde is stabilized. Can be controlled. Moreover, since the volume change amount of the water in the tank 12 is always equal to the volume change amount in the sonde 10 as it is, the volume change amount of the sonde 10 is accurately grasped by the magnetostrictive water level sensor 21 installed in the tank 12. Can do.

(Second Embodiment)
FIG. 2 shows a second embodiment of the in-hole loading test apparatus according to the present invention, and the same components as those shown in FIG.
This in-hole loading test apparatus is different from that shown in the first embodiment in the number of double-acting pumps and the driving form thereof. That is, in this in-hole loading test apparatus, two double-acting pumps (pressurized liquid supply means) 30, 31 and a motor 34 for reciprocating the piston rods 32, 33 of these double-acting pumps 30, 31 are provided. It has been.

  The motor 34 includes two output shafts 36 that rotate synchronously via a gear box 35, and a disk 37 is integrally formed at the tip of each output shaft 36. The piston rods 32 and 33 of the double-acting pumps 30 and 31 are connected to each disk 37 in a crank shape.

  Here, the double-acting pumps 30 and 31 are of the same type in which the capacities of the cylinders 38 and 39 and the strokes of the piston rods 32 and 33 are equal, and the tip 32a of one piston rod 32 is the other piston rod. It is connected on the disk 37 so as to be at a position advanced by 90 ° in the central angle of the disk 37 from the tip 33a of 33. Thereby, the piston 41 of one double-action pump 31 is connected so as to perform the above-described reciprocation at a position delayed by a quarter cycle from the piston 40 of the other double-action pump 30.

  In the in-hole loading test apparatus configured as described above, when the motor 34 is rotated and the piston rods 32 and 33 of the two double-acting pumps 30 and 31 are reciprocated, one piston 41 is driven by the other piston 40. In order to perform the reciprocating motion at a position delayed by 1/4 cycle, the cylinder chamber 38a of one double-acting pump 30 and the cylinder chamber of the other double-acting pump 31 are sequentially provided from the water supply pipe 22 into the sonde 10. 39a, pressurized water is supplied from the cylinder chamber 38b of one double-acting pump 30 and the cylinder chamber 39b of the other double-acting pump 31.

  Therefore, this in-hole loading test apparatus can obtain the same effect as that shown in the first embodiment, and the piston rods 32 and 33 of the two double-acting pumps 30 and 31 are further moved by the motor 34. Since it is reciprocated, further labor saving can be achieved. In addition, since the piston 41 of one double-acting pump 31 is arranged so as to perform the above-described reciprocating motion at a position delayed by a quarter cycle from the piston 40 of the other double-acting pump 30 by the motor 34, The effect that the pressure fluctuation of the pressurized water supplied to the sonde 10 can be suppressed small is also acquired.

  In the first and second embodiments described above, only the case where the magnetostrictive water level sensor 21 is installed in order to measure the water level in the tank 12 has been described. However, the present invention is not limited to this. Instead, the water level in the tank 12 may be recorded visually using a general scale.

  The in-hole loading test apparatus using the manual double-acting pump 11 shown in the first embodiment and the two double-acting pumps 30 and 31 shown in the second embodiment are connected to the motor 34 by a quarter cycle. Using the in-hole loading test apparatus driven by the phase difference and the in-hole loading test apparatus of the comparative example in which one double-acting pump was driven by a motor, the pressure change in the sonde and the flow rate of the pressurized water were measured.

FIG. 3A shows the result of the first embodiment, FIG. 3B shows the result of the comparative example, and FIG. 3C shows the result of the second embodiment.
From these figures, in the first embodiment using the manual double-acting pump 11, since the pressure handle 17 is operated by a person, the fluctuation range of the pressure is not regular, but the fluctuation range is substantially zero. It can be seen that it is stable within 2 Mpa.

  On the other hand, in the comparative example in which one double-acting pump is motor-driven, the pressure fluctuation shows a regular sine waveform, but the fluctuation width is 0.3 Mpa, which is a larger value than in the first embodiment. . On the other hand, in the second embodiment in which two double-acting pumps are motor-driven with a phase difference, it can be seen that the fluctuation range is 0.1 Mpa, and finer control is possible.

10 Sonde 11, 30, 31 Double acting pump (pressurized liquid supply means)
12 tanks 13 pressure gauge (pressure detection means)
14a, 14b, 38a, 38b, 39a, 39b Cylinder chamber 15, 40, 41 Piston 16, 32, 33 Piston rod 21 Magnetostrictive water level sensor (measuring means)
22a, 22b Discharge side piping

Claims (1)

A sonde disposed in a test hole formed in the ground; a pressurized liquid supply means for supplying a pressurized liquid into the sonde; a pressure detection means for detecting the pressure in the sonde; In-hole loading test apparatus provided with a measuring means for detecting displacement of the inner wall of the test hole
The pressurized liquid supply means includes a stroke identical two double-acting pump of the piston rod, a tank for supplying the liquid to the cylinder chambers of the front and rear of these double-acting pump piston, these double acting pump A motor for reciprocating the piston rod, and a discharge side pipe for introducing pressurized liquid from the cylinder chambers of the double-acting pump into the sonde.
The two piston rods are connected to the motor so that one of the pistons performs the reciprocating motion at a position delayed by a quarter of the cycle of the other piston. An in-hole loading test apparatus which is a water level sensor which is installed in a tank and detects the liquid level of the liquid.

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