JPS6331610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sonde for a lateral loading test device that measures lateral ground strength using an excavated hole such as a borehole.

Conventionally, sondes for lateral loading test equipment can be roughly divided into rubber tube-type sondes, in which a rubber tube expands under fluid pressure inside and presses the hole wall, and sondes in which a metal loading plate is pressed with a jack to press the hole wall. There are two types of sondes: rigid plate type sondes that press against the ground. However, in the case of a rubber tube-type sonde, when loaded under high pressure, especially when the hole diameter is large and the amount of expansion is large, the rubber tube, especially its shoulders (near the attachment points at both ends of the rubber tube), may move along the hole wall. There is a drawback that high pressure cannot be applied because there is a risk of bulging in the axial direction of the hole, exceeding the strength limit of the rubber material and causing a puncture. To solve this problem, a steel mesh cover is placed over the outer peripheral surface of the rubber tube, and the strength of the steel wire is used to prevent punctures at the shoulder of the rubber tube. However, in order to inflate the rubber tube smoothly, it is not possible to use a wire that is too thick, so in the end it can only withstand pressures that are within the strength limit of a thin wire.Also, if the hole diameter is large, the shoulders will yield and the wire will collapse. In some cases, the diameter of the shoulder portion may not return to its original state, and even if the pressure is reduced, the diameter of the shoulder portion remains large, creating another problem in that there is a high risk of accidents such as jamming.

On the other hand, in the case of a rigid plate type sonde, a jack for pushing the loading rigid plate must be built inside the sonde, and due to space considerations, the shape and dimensions of the loading rigid plate cannot be increased, and the stroke length also increases. In addition to shortcomings such as being short, there are also economic problems such as the manufacturing cost being much higher than in the case of rubber tubes.

The present invention has been made in view of the actual state of the prior art, and its purpose is to reliably prevent damage to the shoulder portion, which is a drawback of rubber tube type sondes, and to prevent damage to the shoulder portion, which is a drawback of rubber tube type sondes. It is an object of the present invention to provide a sonde for an in-hole lateral loading test device that can utilize the advantages as they are, increase the range (pore diameter) that can withstand high pressure, and has a relatively simple structure.

In order to achieve this object, the sonde of the present invention has a rubber tube inserted into a cylindrical guide column, a loading plate removably fitted into an opening in the peripheral wall of the guide column, and a pressurized fluid supplied to the rubber tube. Guide me,
The expansion causes the loading plate to protrude outward and is configured to load laterally within the hole.

Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 shows an outline of the sonde according to the present invention, where A shows the shape of the sonde before pressurization, and B shows the shape of the sonde before pressurization.
1 and 2 respectively show the configuration of the sonde at the time of pressurized expansion. Also, Figure 2 A and B are respectively similar to Figure 1 A and B.
shows a cross section of The device mainly consists of a cylindrical steel guide column 1, a rubber tube 2 inserted into the guide column 1, and a loading rigid plate 3 built into the guide column 1. The cylindrical guide column 1 is provided with two elongated openings extending along the axial direction at opposing positions on its outer periphery, and the loading rigid plate 3 is provided with two elongated openings extending along the axial direction. It is fitted in such a way that it can appear freely.

The loading rigid plate 3 is axially divided into three parts: an upper rigid plate 3a, a central rigid plate 3b, and a lower rigid plate 3c, which are locked to each other, and the rubber tube 2 located inside has a sealing property. It is fixed with screws that take into consideration the following, and synchronizes with the movement of the rubber tube 2. Both sides of the loading rigid plate 3 are provided with guide columns 1
The rubber tube 2 expands only in the direction in which the loading rigid plate 3 is attached when pressurized, and the guide column surface is constructed such that it cannot expand due to the rigidity of the column.

In addition, as mentioned above, the loading rigid plate 3 divided into three
Of these, the upper and lower rigid plates 3a and 3b have a structure that prevents them from coming off the guide column 1, and suppress expansion of the shoulder portion of the rubber tube 2. Central rigid plate 3b
is sandwiched between an upper rigid plate 3a and a lower rigid plate 3c, and the contact surface thereof is a type of hinge joint that can freely rotate.

A displacement detection sensor 4 is provided inside the rubber tube 2 to detect the amount of movement of the central rigid plate 3b, convert it into an electrical signal, and lead it to the ground via a signal cable 5. Of course, a pressurizing tube 6 is attached to the rubber tube 2, and high pressure fluid is introduced from a pressurizing device on the ground.

Now, such a sonde is inserted into a borehole in the state shown in FIG. 1A and FIG. 2A. When a predetermined position in the hole is reached, high-pressure fluid is forced into the rubber tube 2 inside the sonde from the ground through the pressurizing tube 6. Then, rubber tube 2
expands, and the loading rigid plate 3 accordingly protrudes outward, exerting a lateral force on the hole wall (see FIGS. 1B and 2B). In addition, the rubber tube 2 is
Since it is surrounded by the cylindrical guide column 1 and the loading rigid plate 3, loading pressure can be transmitted to the loading rigid plate 3 without causing damage such as puncture due to high pressure. The amount of displacement of the ground is detected by measuring the amount of movement between the central rigid plates 3b using the displacement detection sensor 4. In this way, the strength constant of the ground can be detected in a stable manner by measuring the relationship between "pressure and displacement" ranging from low pressure to high pressure. After the measurement, the pressurized fluid in the rubber tube 2 is removed. Then, the rubber tube 2 returns to its original thickness, and since the loading rigid plate 3 is fixed to the rubber tube 2, the guide column 1 moves in sync with the movement.
1A and 2A, as shown in FIG. 1A and FIG. 2A. Therefore, after that, it is only necessary to move it to another point within the hole or pull it out.

An embodiment of the sonde according to the present invention is shown in FIG. Portions corresponding to the schematic diagram of FIG. 1 are given the same reference numerals, and description thereof will be omitted. The engagement E between the guide column 1 and the upper or lower rigid plates 3a, 3c is achieved by the protrusions 10, 1 facing each other with a gap in between.
1, and thereby the amount of displacement of the upper rigid plate 3a and the lower rigid plate 3c from the guide column 1 is regulated. Upper or lower rigid plates 3a, 3c
The locking F between the center rigid plate 3b and the ridge 12 and the groove 1
3, and can be bent to some degree at an arbitrary angle at the locking portion F like a hinge.

The remarkable point in this embodiment is that these loading rigid plates 3
An outer rubber tube 14 is further placed over the outside of the tube. Both ends of the outer rubber tube 14 are fixed to the guide column 1 by clamping fittings 16 via presser fittings 15, respectively. This outer rubber tube 14 prevents muddy water and other foreign matter from entering the joint between the separated loading rigid plates 3 or the boundary between the loading rigid plates 3 and the guide column 1. It functions to prevent interference with free movement of appearance and appearance.

Next, the connection relationship between the loading rigid plate 3 and the rubber tube 2 will be described. As shown in the enlarged view, the rubber tube tightening screw 21 is inserted into the rubber tube 2 via the seal washer 20, screwed onto the seal nut 22 on the inside, and the non-penetrating nut portion provided at the center of the rubber tube tightening screw 21 is connected to the load. The loading rigid plate 3 is fixed to the rubber tube 2 by plate fixing screws 23. Therefore, the sealing performance of the rubber tube 2 is maintained. Further, the guide column 1 is fixed to the sonde body so as not to be deformed by high pressure. As shown in the enlarged view below, the rubber tube 2 is screwed and sealed onto the sonde body 26 by a seal washer 20 and a rubber tube tightening screw 25, and a rubber tube tightening screw 25 is provided at the center of the rubber tube tightening screw 25. The guide column 1 is fixed by the nut portion and the guide column reinforcing screw 24.

The operation of the sonde shown in this example is the same as outlined in FIG.

As described above, the present invention has the following advantages: Since the rubber tube is surrounded by guide columns and rigid loading plates, there is no risk of the rubber tube being damaged, and high pressure loading tests are possible. Because it has a rigid plate-loaded structure, the effective displacement measurement amount can be larger than that of the conventional jack-type rigid plate-loaded sonde.
The structure is simple and economical, and the loading rigid plate is separated into three or more parts, so the central rigid plate detects the amount of displacement, and the rigid plates located at the upper and lower ends detect the displacement. Since it acts as a guide plate, it is possible to accurately measure the relationship between ground displacement and applied force.
Since the loading rigid plate is fixed to the rubber tube, it synchronizes with changes in internal pressure, returns to its original shape when the pressure is reduced, and has many excellent effects, such as preventing accidents such as jamming. It is something that can be played.

[Brief explanation of the drawing]

FIGS. 1A and 1B are schematic explanatory diagrams of the present invention, respectively;
2A and 2B are sectional views thereof, and FIG. 3 is an explanatory view showing one embodiment of the present invention. 1... Guide post, 2... Rubber tube, 3...
...Rigid plate for loading, 3a... Upper rigid plate, 3b... Center rigid plate, 3c... Lower rigid plate, 4... Sensor for displacement detection, 5... Signal cable, 6... Pressure tube.

Claims (1)

[Claims] 1. A cylindrical guide column having an opening extending along the axial direction formed on the outer periphery, a rubber tube inserted into the inside of the guide column, and a loading plate fitted in the opening so as to be freely retractable. The loading plate is divided into three or more parts in the axial direction and are locked to each other, and is fixed to the rubber tube surface, and the loading plates at both ends are locked to prevent them from falling off the guide column. Sonde for in-hole lateral loading test equipment.