JPH0516488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an apparatus for an automatic standard penetration test performed for the purpose of measuring the N value and observing a sample. 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 starting depth is reached, and a sampler and boring rod are connected to this hole and lowered to the bottom of the hole. Attach the knotting head to the top of the boring rod,
Gently place the hammer on this notching head. Perform a preliminary strike with the hammer falling height 15 cm or less. The falling height of the hammer
Keep it at 75cm and let it fall freely. 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), measure the number of blows N required to penetrate 30 cm.

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

The Khonpuri method is a method in which a rope is wrapped around a Khonpuri (commonly known as Giyandra) and a hammer is suspended and dropped.

The free fall method is a device that mechanically causes the hammer to fall 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 hammer weighing 63.5 kg dozens or even hundreds of times using a hoisting rope. However, 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 completely release the rope from the pulley when the hammer falls, which is cumbersome. Because the rope was manipulated, it was easy to be inaccurate in ensuring a fall height of 75 cm, 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 lowers the reliability of the N value.

"Means for Solving the Problems" The present invention has been made 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 a compressed air supply path that is fitted to be able to move up and down and raises the hammer by a predetermined length within the cylinder, and this switching control valve controls switching in response to the up and down movement of the hammer. This device is used by suspending and setting the device into the hole using a wire rope.

``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. When the hammer rises a predetermined distance (75 cm), a switch is turned on and the switching control valve changes, 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 notching head through 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” An example of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a boring machine, and this boring machine 1 is installed on a measuring ground 2. A boring hole 3 is excavated at the measurement position of the measuring ground 2, and a drive pipe 4 is fitted near the ground. A sampler 6 is set at the bottom of the hole, and a vertically elongated cylinder 7 is connected to its upper end. The bottom of this cylindrical body 7 constitutes a knotting head 8, into which a vertically movable hammer 9 is fitted, and the upper end is provided with a flow path switching control valve 10 and a changeover switch 11. Air supply path 12 is connected to 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 plate 8 which also serves as a knocking head is airtightly attached to the lower end of the cylindrical body 7, and a lid body 16 and a valve body 17 are attached to the upper end. installed. Between the valve body 17 and the bottom plate 8, there is a
The air guide tube 18 is fixed, and the hammer 9 is fitted so as to be vertically movable. In addition, valve body 1
The distance from the bottom surface of 7 to the top surface of bottom plate 8 is 185 cm.
The length of the hammer 9 is 110 cm, so the falling height of the hammer 9 when it reaches the highest point is 75 cm. A gunmetal guide 19 is wound around the upper end of this hammer 9, a packing 20 is wound around the lower end, and a weight 21 is formed at the center part, so that the hammer 9 as a whole has a 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.

A control valve hole 25 is bored in the valve body 17 so as to communicate with the upper chamber 24 of the hammer 9. Inside the control valve hole 25, two upper and lower control valves 26 and 27 are arranged with a coil spring between them. The upper hole 29 of the control valve hole 25 communicates with the upper hole 31 of the orifice 30, the lateral hole 32 communicates with the lower hole 33 of the orifice 30, and the lower hole 33 communicates with the air guide. It communicates with the pipe 18.

Between the lid body 16 and the valve body 17, there is provided a switching control valve 10 consisting of a solenoid valve, and a switching switch 1 that switches the switching control valve 10 in response to the vertical movement of the hammer 9.
1 is provided. Further, an air supply port 12 is formed from the upper end of the lid body 16, and this air supply port 12
is branched into a supply port 34 and a discharge port 35 to the orifice 30 side within the switching control valve 10, and these supply port 34 and discharge port 35 are provided with valves 49 and 50, respectively. An outlet 36 to the atmosphere is provided.

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

Next, to explain the control circuit, the microcomputer 38 that plays a central role in control includes a ROM 39 that stores programs, a RAM 40 that stores data, etc.
A printer 41, a display section 42 such as a CRT, an XY plotter 43, and an input/output section 44 are combined, and the input/output section 44 includes a keyboard 45, a valve control section 46, a driving depth input section 47, and an N value input section 48 are combined.

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 by the boring machine 1, the start depth and end depth of the preliminary drilling are measured, and the data is displayed on the display section 42 via the input/output section 44 and the microcomputer 38. and is printed on the printer 41.

Next, the sampler 6 is connected to the lower end of the boring rod 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 boring rod 5 and 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 subsidence is 45cm or more, the test will be terminated.

(2) When the settlement is less than 45 cm, attach the cylindrical body 7 of the present invention to the upper end of the boring rod 5.

(3) When it sinks under its own weight, record it in RAM40,
This will be displayed on the display unit 42, and if the settlement is 45 cm or more, the test will end.

(4) If the settlement is less than 45 cm, move the hammer 9 to the cylinder 7.
Lift it up to a height of 75cm inside and let it fall freely.

(5) The number of blows required to penetrate 30 cm (N value) while recording the amount of penetration for each blow (or the amount of penetration for every 10 blows if the amount of penetration per blow is less than 2 cm) in RAM40.
Measure. In this case, unless otherwise required, 50
The test is completed by recording the cumulative amount of penetration.

(6) Rotate the boring rod 5 and sampler 6
Cut the edge between the inner soil and the ground.

(7) Pull up sampler 6.

(8) Observe sample length, soil type, contained substances, etc.
The information is entered in a field notebook and further recorded 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 a command from the microcomputer 38.
valve 49 is opened and valve 50 is closed. Then, compressed air from the pump 13 is supplied from the supply port 12, and the control valves 26, 27 move down against the coil spring 28 to close the horizontal hole 32. At the same time, compressed air is supplied to the air guide pipe 18 through the orifice 30, and this air is further supplied to the lower chamber 23 of the hammer 9 through the lower hole 22, so that the hammer 9 gradually rises. 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, it pushes up the plunger 37, operates the changeover switch 11, closes the valve 49 of the changeover control valve 10, and opens the valve 50, so that the supply of air from the pump 13 is cut off.
And the inside is open to the atmosphere. Therefore, the control valve 26 is raised by the coil spring 28 and 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 communicates with the atmosphere through the horizontal hole 32 and the upper chamber 24 of the hammer 9, so the hammer 9 falls freely within the cylinder 7. . The bottom plate 8 serves as a knocking head for the hammer 9.
It is transmitted to the boring rod 5 and the sampler 6 through the hole, 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. Furthermore, since the device is equipped with a hammer inside a cylinder, a changeover control valve, and a changeover switch, the error during operation is extremely small compared to the conventional self-dropping method. Since the entire device is small and lightweight, it can be suspended into a hole, eliminating the need to correct coefficients based on measurement depth.

[Brief explanation of drawings]

The figure shows an embodiment of the automatic standard penetration testing device according to the present invention, and FIG. 1 is an overall block diagram;
FIG. 2 is an explanatory view of an example of the display on the display section, FIG. 3 is a sectional view of the inside of the cylinder, and FIG. 4 is a sectional view of FIG. 3 when the hammer falls. 2... Ground, 3... Boring hole, 5... Boring rod, 6... Sampler, 7... Cylindrical body, 8... Knocking head, 9... Hammer, 10... Switching control valve,
11...Switch.

Claims (1)

[Claims] 1. A vertically elongated cylindrical body is attached to the upper end of the sampler that is penetrated into a borehole drilled in the ground, and a piston-shaped hammer is fitted into this cylindrical body so as to be able to move up and down, and this hammer is inserted into the cylinder. A switching control valve is provided in the supply path of compressed air that is raised by a predetermined length within the body, and a switch is coupled to the switching control valve to control switching in response to the vertical movement of the hammer. Automatic standard penetration testing equipment. 2. The automatic standard penetration testing device according to claim 1, wherein the switching control valve is a solenoid valve.