JPS6246230A - Automatic standard penetration test apparatus - Google Patents

Abstract

PURPOSE:To facilitate the measurement of a N-value (the impact number of times required in the penetration of a constant length), by automatically performing the falling of a hammer only by the control of compressed air. CONSTITUTION:When the valve 49 of a change-over valve 10 is opened and the valve 50 thereof is closed by the order from a microcomputer, compressed air is supplied from a supply port 12 and control valves 26, 27 are fallen against a spring 28 to close a transverse hole 32. At the same time, compressed air is supplied to a lower surface chamber 23 from the lower hole 22 of an air guide pipe 18 through an orifice 30 and a hammer 9 rises to exhaust air of an upper surface chamber 24. When the hammer 9 reaches the uppermost point, a plunger 37 is pushed up and a change-over switch 11 is operated and the valve 49 is closed while the valve 50 is opened. Because of this, the supply of air is cut off and the control valve 26 rises by the string 28 to open the transverse hole 32. Because air of the lower surface chamber 23 reversely flows through a pipe 18 and passes through the upper surface chamber 24 from the transverse hole 32 to be communicated with the open air, the hammer 9 falls freely in a cylinder 7. The impact of the hammer 9 is transmitted through a bottom plate 8 and a sampler is driven into ground. This operation is repeated to measure a N-value.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention is directed to automatic oscillation 4I! which is carried out for the purpose of measuring N value and wlrA of a sample. This invention relates to a device for penetration testing. More specifically, during boring, the sampler is driven into the soil using the impact force of a hammer, and a soil sample is collected. This relates to equipment for the so-called standard penetration test that measures the hardness and compactness of soil.

"Conventional technology" It is important to know the hardness and compactness of the soil when preparing foundations when constructing structures, and when excavating tunnels for subways, sewers, etc., and based on this knowledge, it is necessary to take measures to stabilize the ground, such as chemical injection, etc.
The selection of construction methods such as pile driving will be decided. A standard penetration test is generally used to measure the hardness, softness, and compactness of these soils.

In this standard penetration test, a hole is first drilled in the ground until the test start depth is reached, and a sampler and boring rod are connected to this hole and lowered to the bottom of the hole. Attach the knocking head to the top of the boring rod and gently place the hammer on top of the knocking head. The falling height of the hammer is 15c.
Make a preliminary strike as m or less. Keep the falling height of the hammer at 75 elm and let it fall freely. Blow 1
Penetration amount per time (10 if the penetration amount per time is less than 2 cm)
The number of blows N required to penetrate 30 cm is measured while recording the amount of penetration (each time).

However, three methods have been used in the past for hanging and dropping the hammer: the hopper method, the corn pull method, and the automatic drop method.

The dragonfly method involves suspending the bent part of an L-shaped dragonfly with a hanging ring.
This method involves suspending a hammer from the hook-shaped part and pulling the other end with a string to allow the hammer to fall freely.

The Khon Puri method is Khon Puri (commonly known as Candra).
This method involves wrapping a rope around the hammer and suspending it from the hammer.

The free fall method is a device that mechanically drops the hammer when it rises to a certain height (75 cm).

``Problems to be Solved by the Invention'' The above-mentioned tomb method is not only difficult, but also requires several people to pull up a 63.5 kg hammer dozens or hundreds of times using a hoisting rope. There was a problem in that the hammer had to be locked every time it fell, which was extremely troublesome.

The cone pulley method has a problem in that the edge of the rope and the hammer cannot be cut, so the falling energy is reduced due to friction between the rope and the pulley, and between the rope and the cone pulley. In order to prevent this, it is necessary to always lubricate the pulley and to completely release the rope from the pulley when the hammer falls, which is cumbersome. , it was easy to ensure a drop height of 75 cm inaccurately, and great care was required during the work.

Although the automatic dropping method is the most ideal, it still has many inconveniences, such as the height of the bowling tower becoming high and the entire device becoming heavy.

A more serious problem is that all of the above-mentioned methods have a structure in which the impact force is transmitted to the sampler at the tip via the rod, so as the measurement depth increases, the impact force is weakened due to the deflection of the rod. Therefore, it is necessary to correct it using a coefficient, which reduces the reliability of the N value.

``Means for Solving the Problems'' The present invention was made in order to solve the above-mentioned problems.A vertically long cylinder is attached to the upper end of the sampler, and a piston-shaped hammer is installed inside the cylinder. A switching control valve is provided in the compressed air supply path that is fitted to be vertically movable and raises the hammer by a predetermined length within the cylinder, and the switching control valve has a
It is composed of a switch that controls switching in response to the vertical movement of the hammer, and is used by suspending one device into the hole with a wire rope and setting it.

"Operation" The compressed air supply path is switched to the lower chamber side of the hammer by the switching control valve, compressed air is supplied to the lower part of the hammer, and the hammer is gradually raised. The hammer moves at a predetermined distance (75
cm) When the hammer rises, a switch is turned on and the switching control valve is switched over, opening the air supply path below the hammer to the atmosphere and allowing the hammer to fall freely.

Then, the impact of this hammer is applied to the knocking head via the cylinder, and further to the sampler via the boring rod. The number of hits required for the sampler to be driven 30 cm into the soil is measured, and this number is the N value.

"Example" Hereinafter, one embodiment of the present invention will be described based on the drawings.

(1) is a boring machine, this boring machine (1) is installed on the measuring ground (2), and a boring hole (3) is drilled at the measuring position of this sub-chamber ground (2), and it is located near the ground. The drive pipe (4) is fitted. A sampler (6) is set at the bottom of the hole, and a vertically long cylinder (7) is placed at the top end of the sampler (6).
) are combined. The bottom of this cylindrical body (7) constitutes a knocking head (8), into which a vertically movable hammer (9) fits, and the upper end includes a flow path switching control valve (1).
0) and a changeover switch (11), and an air supply path (12) at the upper end is connected to a pump (13).

Further, a wire (15) of a driving depth measuring device (14) is connected to the upper end of the cylinder (7).

To explain the inside of the cylindrical body (7) in more detail with reference to FIG. 3, a bottom opening (8) that also serves as a knocking head is airtightly attached to the lower end of the cylindrical body (7), and a
A lid body (16) and a valve body (17) are attached. An air guide pipe (18) is fixed in the center between the valve body (17) and the bottom hole (8), and a hammer (9) is fixed in the center.
) are fitted so that they can move up and down. The distance from the bottom surface of the valve body (17) to the top surface of the bottom hole (8) is 185 cm, and the length of the hammer (9) is 110 cm. 9) The falling height is 75cm. A gunmetal guide (19) is attached to the upper end of this hammer (9), and a packing (20) is attached to the lower end.
) is wound, and the central part forms a weight (21), and the hammer (9) has a total weight of 63.5 kg.

The lower hole (22) of the air guide tube (18) communicates with the lower chamber (23) of the hammer (9).

The valve body (17) has an upper chamber (24) of the hammer (9).
) A control valve hole (25) is bored in communication with the control valve hole (25), and within this control valve hole (25) are two upper and lower control valves (26) (
27) is provided with a coil spring (28) interposed therebetween, and the upper hole (29) of this control valve hole (25) is connected to the orifice (
The lateral hole (32) communicates with the upper hole (31) of the orifice (30), and the lower hole (33) communicates with the air guide pipe (18). There is.

Between the lid body (16) and the valve body (17), there is a changeover control valve (10) consisting of a solenoid valve and a changeover switch that changes over the changeover control valve (lO) in response to the vertical movement of the hammer (9). (
11) is provided. Further, an air supply port (12) is formed from the upper end of the lid (16).
2) the orifice (30) within the switching control valve (10);
It is branched into a supply port (34) and a discharge port (35) to the side, and these supply ports (34) and discharge ports (35) are equipped with valves (49).
(50), and the lid (16) is further provided with an exhaust port (36) to the atmosphere.

A plunger (37) is provided on the valve body (17) so as to be able to move up and down, the upper end of this plunger (37) faces the changeover switch (11), and the lower end is connected to a hammer ( 9) is provided so as to slightly protrude into the upper chamber (24).

Next, to explain the control circuit, the microcomputer (38) that forms the center of control has an R O
M (39), R A M (40) that stores data etc.
), printer (41), display unit (42) such as CRT,
An xy plotter (43) and an input/output section (44) are combined,
This input/output section (44) includes a keyboard (45) and a valve control section (46).

A driving depth input section (47) and an N value input section (48) are coupled.

Next, the operation of the device according to the present invention will be explained.

A preliminary boring hole (3) is drilled in the ground (2) using a boring machine (1), the start and end depths of the preliminary drilling are measured, and the result is passed through the input/output section (44) and the microcomputer (38). The data is displayed on the display section (42) and printed on the printer (41).

Next, the sampler (6) is connected to the lower end of the Pauline Blond (5) and lowered to the bottom of the borehole (3).

At this time, the sampler (6) is gently lowered to the bottom from about 1 m, which reaches the planned depth.

The measurement work order after inserting the sampler (6) is as follows.

(1) Measure whether the Pauline Blond (5) and the sampler (6) have sunk under their own weight, and if they have sunk under their own weight, record it in the RAM (40) and display it on the display section (42).

If the settlement is 45CI11 or more, the test is terminated.

(2) When the settlement is less than 45 cff1, attach the cylindrical body (7) of the present invention to the upper end of the Pauline Blond (5).

(3) When the sinking due to its own weight occurs, it is recorded in the RAM (40) and displayed on the display section (42). If the sinking is 45 cI11 or more, the test is terminated.

(4) If the settlement is less than 45 cm, lift the hammer (9) within the cylinder (7) to a height of 15 cm and allow it to fall freely.

(5) While recording the amount of penetration for each blow (if the amount of penetration per blow is less than 2 cm, the amount of penetration for every 10 blows) in RAM (40), calculate the number of blows (N value) required to penetrate 30 cm. Measure. In this case, the test ends after recording the cumulative amount of penetration 50 times, unless otherwise necessary.

(6) Rotate Pauline Blonde (5) and sampler (
6) Cut the edge of the soil inside and the ground.

(7) Pull up the sampler (6).

(8) Evaluate the sample length, soil type, color tone, content, etc., write it in the field notebook, and record it in the RAM (40) from the keyboard (45) via the microcomputer (38).

Next, the automatic dropping operation of the hammer (9) will be explained.

The switching control valve (10) is activated by commands from the microcomputer (38).
The valve (49) is opened and the valve (50) is closed. Then, compressed air from the pump (13) is supplied from the supply port (12), and the control valves (26) (27) are connected to the coil spring (28).
The horizontal hole (32) is closed by descending against the pressure. At the same time, the compressed air passes through the orifice (30) to the air guide tube (18).
), this air is further supplied from the lower hole (22) to the lower chamber (23) of the hammer (9), and the air is further supplied to the lower chamber (23) of the hammer (9).
9) gradually increases. At this time, the air in the upper chamber (24) of the hammer (9) is exhausted to the atmosphere.

When the hammer (9) reaches the highest point, the plunger (
37), actuates the changeover switch (11), closes the valve (49) of the changeover control valve (10), and opens the valve (50). Therefore, the supply of air from the pump (13) is cut off. , and the interior is open to the atmosphere. Therefore, the control valve (2
6) is raised by the coil spring (28) and enters the horizontal hole (32).
) opens. Then, the air in the lower chamber (23) of the hammer (9) flows back through the air guide tube (18) and enters the horizontal hole (3).
2) through the upper chamber (24) of the hammer (9) to the atmosphere, the hammer (9) falls freely within the cylinder (7). The impact of the hammer (9) is transmitted to the boring rod (5) and the sampler (6) via the bottom plate (8) which also serves as a non-king head, and the sampler (6) is driven into the soil.

Thereafter, the N value is measured by repeating the same operation.

Note that this N value may be determined by using a signal from the changeover switch (11).

"Effects of the Invention" Since the present invention is configured as described above, the hammer can be automatically dropped simply by controlling compressed air, and the N value can be easily measured. Also, since the device is equipped with a hammer inside a cylinder, a switching control valve, and a switching switch,
Compared to the conventional self-dropping method, there are extremely few errors during operation. 'The entire device is small and lightweight, so it can be suspended into a hole, eliminating the need to correct coefficients based on measurement depth.

[Brief explanation of the drawing]

The figures show an embodiment of the automatic standard penetration testing device according to the present invention, in which Fig. 1 is an overall block diagram, Fig. 2 is an explanatory diagram of an example of the display on the display section, and Fig. 3 is a cross section of the inside of the cylinder. FIG. 4 is a cross-sectional view of FIG. 3 when the hammer falls. (2)...Ground, (3)...Borehole, (5)
... Boring rod, (6) ... Sampler, (
7)...Cylinder body, (8)...Knocking head, (9
)・Hammer, (lO)...Switching control valve, (11)・
··switch. Applicant: Nippon Boring Co., Ltd. Tobu Denki Kogyo Co., Ltd.

Claims (2)

[Claims] (1) A vertically long cylindrical body is attached to the upper end of the sampler that is penetrated into a borehole drilled in the ground, a piston-shaped hammer is fitted into this cylindrical body so as to be able to move up and down, and this hammer is moved to a specified length within the cylindrical body. In the supply path of compressed air that raises only
An automatic standard penetration testing device comprising a switching control valve, and a switch coupled to the switching control valve for controlling switching in response to the vertical movement of the hammer. (2) The switching control valve is a solenoid valve.
Automatic standard penetration test equipment as described in Section.