JP2001032252A - Borehole loading test method, and functional hole holding pipe type borehole loading test apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for easily carrying out the horizontal borehole loading test and the shear test of a collapsible ground. SOLUTION: In boring the ground, a hole holding pipe 1 for preventing collapse of a hole wall with a hole wall pressurizing pipe 10 to be simultaneously bulged in the radial direction connected to a lower end thereof is inserted, and stopped at a specified depth, and the wall pressurizing pipe is bulged and closely attached to the hole wall to carry out the horizontal borehole loading test. In addition, the friction and shear test is carried out by applying the pull-up force to the hole wall pressurizing pipe with the hole wall pressurizing pipe closely attached to the hole wall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-hole load test apparatus for performing a horizontal load test or a shear test on a hole wall in a borehole for geological investigation and obtaining ground information by an in-situ test.

[0002]

2. Description of the Related Art Among in-situ in-hole tests, a "horizontal load test method in a hole" in which a hole wall is pressed by an inflatable cell to perform a horizontal load test is based on the standard (GJS1421-
1995). This test is a pre-boring method in which a cell is inserted into a hole after boring and a loading test is performed. In addition, there is a self-boring type in which a cutting shoe is attached to the lower end of the cell to set the cell while digging. In addition to the above, in addition to the above, a testing apparatus for performing a shear test in a state where the hole wall is pressurized to obtain an internal friction angle of the ground, an adhesive force, and a shear strength has been developed (for example, Patent No. 690755). No .: Ground shear test equipment).

[0003]

The pre-boring type horizontal loading test in a hole is based on the premise that the hole wall does not collapse after boring and before setting the cell. Therefore, it may not be possible to measure on collapsed ground. In addition, disturbance of the ground due to drilling, release of the ground pressure, and disturbance of the ground of the hole wall due to drilling mud are also problems. In order to overcome these drawbacks, a self-boring type, which is a digging type, has been developed (for example, Japanese Patent No. 1223556: a device for measuring the strength and deformation characteristics of soil using a boring hole wall). However, the focus of this development was to obtain more accurate ground information, which required advanced operation techniques such as minimizing changes in ground pressure as much as possible. Since it was a device, it did not spread.

On the other hand, a method of performing a shear test while pressing a hole wall has been used as a technique for obtaining ground information on a rubble-like ground where it is difficult to collect a sample without disturbing the ground.
However, in some cases, it is not possible to insert a cell for shear test after drilling on collapsible ground.Similar to horizontal loading test in the hole, self-boring method has been developed, but complicated mechanism and advanced operation It is not widely used because it is necessary.

[0005]

In order to solve such a problem, the present invention is capable of performing a test more reliably on collapsible ground rather than obtaining high-precision ground information with a focus on development, and is academically high. Although the evaluation cannot be expected, it was done by making it possible to easily obtain the ground information with the accuracy required in the design practice.

That is, in the test method of the present invention, a hole wall pressurizing tube bulging in the radial direction is simultaneously inserted into a hole wall preventing hole hole preventing tube connected to a lower end at the time of boring of the ground to a predetermined depth. After stopping, the hole wall pressurizing tube is expanded and brought into close contact with the hole wall to perform a horizontal loading test in the hole, and further, the hole wall pressurizing tube is kept in close contact with the hole wall. This is a method for testing the load in a hole, wherein a friction / shear test is performed by applying a pulling force to a hole.

Further, the test apparatus of the present invention is provided with a cutting shoe at the lower end, a hole wall pressing portion having a plurality of axial slits formed in the outer peripheral surface in the circumferential direction, and a drilling bit inside the lower end. A lower hole tube rotatably mounted, a hole / load transmission tube comprising an upper hole tube loosely connected to the lower tube, and a hole tube having the lower hole / load transmission tube coupled to a lower end; ,
A drilled rod which is inserted into the borehole pipe and the borehole / load transmission pipe and whose distal end is detachably connected to the borehole bit, and inserted into the borehole pipe and the borehole / load transmission pipe by the insertion rod. A pressurizing cell that presses the pressurizing portion closely to the hole wall by pressing the hole wall pressurizing portion of the lower perforated tube from the inside, and connects a connecting member to the lower perforated tube with the lower perforated tube. A connection member with the upper hole tube is provided so as to be freely engageable with the upper hole tube, and a connection member installation portion with the lower hole tube and a connection member installation with the upper hole tube And a pressure measurement device having an axial load cell mounted between the pressure measurement device and the pressure measurement device. And a tapered surface of a tapered shaft piston that moves up and down inside the pressure measuring device as a connecting member with the lower hole tube. It is good to use an inwardly urged shear key member that projects radially by engagement and has its tip portion loosely fitted into key grooves formed in the inner surface of the upper and lower hole tubes. is there.

[0008] The apparatus of the present invention is of a digging type to reliably perform an in-hole test even on collapsed ground. Then, unlike the conventional method, with the main focus on testing quickly without allowing collapse while accepting subtle ground disturbances such as the release of ground pressure, tow a borehole pipe to prevent hole wall collapse while digging And insert it underground,
The problem caused by collapse of the hole wall is solved by pulling up the drilling rod, which is a drilling tool, and then inserting and setting a pressurizing cell or other pressurizing measuring device into the borehole tube. That is, as shown in FIG.
A reaction force projection (2) is provided inside the lower part of the hole, a bit (4) is provided at the tip of a drilling rod (3), and a rotation projection (5) for pulling a hole pipe is mounted above the bit (4). Digging or drilling ahead of a bit so that the borehole pipe can be pulled,
In addition, the provision of a rotation sliding function on the projections so that the bored pipe does not rotate during rotary drilling makes it possible to reliably install the bored pipe.

Next, several slits (6) are formed in the outer peripheral surface of the bored pipe in the axial direction so that the bored pipe can be easily expanded in the hole diameter direction at the test position, and the bored pipe is easily deformed. Notches (7) were provided in the upper and lower portions of the slit as described above. A pressure cell (8) that expands in the diameter direction is inserted into the borehole tube, and a horizontal loading test is performed at the slit so that ground information can be obtained. The pressurization and the change of the diameter can be performed by a pressurization control / measurement / recording device of a generally used horizontal loading test device in a hole (not shown). The shear strength of the ground can be obtained from a shear test in which the above-mentioned pressurized cell is inserted into the borehole pipe and the borehole pipe is pulled up while pressurizing at the ground pressure. Furthermore, a shear test can be performed while sequentially changing the pressing force to determine the friction angle and adhesive strength of the ground, but if the outer surface of the borehole slit is slippery, the slip strength will be determined instead of the ground strength characteristics. Therefore, if necessary, an uneven portion (9) is provided on the outer surface to prevent slipping.

The pulling force of the borehole pipe can be measured with a jack (not shown) on the ground and measured with a load cell. In this method, the pulling force without pressurizing is measured before the shear test to determine the own weight and the borehole. It is necessary to measure and correct the friction of the entire underground part of the pipe. In this method, since there may be a problem of the identity between the test and the friction measurement in advance, a stress measuring unit (11) is provided on the slit (10) by attaching a strain gauge or the like as necessary. In this case, a problem in operation requires a secondary operation such as protecting the signal cable (12) from the stress measuring unit with a special sheath for curing.

In order to further improve the measurement accuracy, as shown in FIG. 2, a load cell (13) is mounted on the upper part of the pressurized cell, and a shear key (1) for transmitting a tensile force with the hole pipe is provided above and below the load cell (13).
4) is provided. A shear groove (15) matching the above-mentioned shear key is provided also in the borehole pipe, and a thrust portion (16) is provided so that a pulling load of the borehole pipe does not act between them.
In addition, a fall-prevention key or the like is provided in advance so that the hole retaining pipe does not separate at the time of installation and removal. In this method, the displacement during the shear test can be measured on the ground part of the rod (17) for the pressurized cell, and the load can be measured by using the borehole in the shear part, the lower shear key, the load meter, the upper shear key and Since the beam is transmitted through the hole pipe to the ground, no load is applied to the rod, and the measurement accuracy of the shear strain is improved.

The drilling bit for drilling differs depending on the type of the target ground, but is set slightly smaller than the outer diameter of the borehole or slightly larger in hard soil. The bit cannot pass through the borehole because of the wall thickness. Therefore, drilling is performed by attaching a bit in advance when setting the borehole tube, drilling and removing the rod at the upper part of the rotating projection at the time of the test, re-feeding after the test is completed, and drilling to the next depth. However, this method makes it difficult to select and replace bits that correspond to changes in the ground. Therefore, the drilling diameter is automatically changed according to the hardness of the ground. It becomes possible. In addition, this method can also be used in combination with a standard penetration test and other in-situ tests at the bottom of a borehole, thereby expanding the practical application range.

[0013]

According to the present invention, it is possible to reliably test even the ground which cannot be measured due to collapse of the hole wall by the prevailing pre-boring method. Further, when compared with the self-boring type which has been conventionally performed as a special test, there is a great advantage that the equipment is lightweight and the work can be performed without depending on a specific operator. In addition, the ability to perform tests at the bottom of a hole, such as a standard penetration test, a horizontal loading test in a hole, and a shear test in a hole in the same hole, has contributed to shortening the process and reducing the cost of investigation.

[0014]

Embodiments of the present invention will be described below. As shown in FIG. 3, the apparatus according to the present invention is connected to the lower end of the borehole pipe (1) to transmit the loading pressure and shear force to the wall of the borehole, and the borehole / load transmission pipe having the bit attached to the lower end. When,
In order to insert the hole and load transmitting tube shown in FIG. 4 which can be inserted and recovered into the hole and the hole and load transmitting tube in a predetermined search, the drill bit is transmitted by transmitting the rotational force and thrust to the bit. While applying a load pressure to the drilling rod (3), which is a drilling tool for pulling the borehole pipe, and the boring hole wall shown in FIGS. Consists of a measuring device.

The structure and function of the hole- holding / load-transmitting tube in FIG . 3 The hole- holding / load-transmitting tube (100) is an upper hole with a shear groove which is an upper hole-pipe connected to the hole-holding tube (1) by screws. Bore tube (2
3), shearing keys (14a) (14b) provided above and below the load cell (13) shown in FIG. 10
In order to facilitate the connection with the shear key grooves (15a) and (15b) of (0), the lower hole tube connected by the falling-off prevention pin (24) of the thrust portion (16) which can freely expand and contract in the axial direction. It is constituted by a certain lower shear grooved hole pipe (25), and a cutting shoe (18) connected to the lower end of the lower shear grooved hole pipe (25) by a screw.

A load meter (FIG. 6) of a pressure measuring device shown in FIG. 6 is used to measure the lifting force applied by a jack (not shown) on the hole tube (1) to the hole tube (23) having an upper shear groove. 13) The shear key (1
A shear key groove (15a) with which 4a) engages is provided. A load cell (1) is attached to the lower shear grooved holding pipe (25).
The shear key (14b) of the pressure measuring device shown in FIG. 6 for transmitting the lifting force from the hole tube (1) transmitted to 3) to the hole tube with lower shear groove (25) is engaged. And a plurality of slits (6) in the axial direction to facilitate diametrical expansion with expansion of the pressure cell (8) of the pressure measuring device shown in FIG. Notches (7a) and (7b) are provided on the upper and lower portions, and a portion which is in close contact with the hole wall is provided with an uneven portion (9) on the outer peripheral surface to prevent slippage with the ground. I have. FIG.
As shown in (1), a fixing key (19) for attaching a bit (4) to the cutting shoe (18) so as to transmit only thrust while preventing the rotational force of the drilling rod (3), a rotary sliding material (20), A bit joint (22) is attached.

In the above-mentioned hole / load transfer tube (100), a hole-piercing tube (23) with an upper shear groove and a hole-piercing tube (2) with a lower shear groove.
5) and the cutting shoe (18) transmit the thrust transmitted to the cutting shoe (18) by the drilling rod (3) to the upper retaining pipe (1) at the time of drilling / inserting, and at the same time, the collapse of the hole wall. It also plays the role of a hole-preventing tube for preventing the occurrence of air. Further, the cutting shoe (18) prevents the circulating water supplied to the bit (4) from flowing out of the hole retaining pipe during drilling. In addition, the upper and lower notches (7) of the slit portion (10), which is a hole wall pressurizing portion of the holding tube (25) with a lower shear groove.
a) The uneven portion (9) excluding (7b) is brought into close contact with the hole wall by the pressure cell (8) of the pressure measuring device shown in FIG. During the shear test, it becomes a part where frictional resistance of the hole wall is generated by the lifting force of the hole pipe (1). A thrust portion (1) for connecting the bored pipe with upper shear groove (23) and the bored pipe with lower shear groove (25)
6) The upper and lower shear key grooves (1) sandwiching the thrust portion
The load cells (1) mounted on the shearing keys (14a) and (14b) of the pressure measuring device shown in FIG.
In 3), the transmission of the frictional resistance generated in the uneven portion (9) by pulling up the hole retaining tube (1) is ensured.

[0018]Configuration and function of drilling rod in Fig. 4  The drilling rod (3) is fixed to the cutting shoe (18).
With a key that transmits torque and thrust to the specified bit (4)
A coupling (21) at the lower end. And with key
Connection (21) to the end of the drilling rod (3)
Into the hole pipe (1) and insert the cutting shoe (1).
Bit join at the upper end of bit (4) fixed to 8)
To the bit by inserting and connecting to the bit (22)
And thrust. Rotation added to drilling rod (3)
Force and thrust are provided by a ground drilling device (not shown).
Can be

[0019]Configuration and function of the pressure measurement device in FIG.  The pressurization measuring device is shown in FIG.
5) Inflate the uneven portion (9) to make it close to the hole wall.
With the lifting of the pressure cell (8) and the hole tube (1)
Resistance generated on the hole wall in contact with the uneven part (9)
Is constituted by a load cell (13) for measuring the load. Pressurized
(8) is expanded membrane solid at both ends of the pressurized cell core pipe (38).
Fix the cylindrical inflatable membrane (36) with the fixing ring (37)
And pressurized liquid between the pressurized cell core pipe (38) and the expansion membrane.
Inflated by pressurized fluid sent through circuit (39)
The lining (36) is expanded. Feed to pressurized liquid circuit (39)
Pressurized fluid to be connected to pressurized hose joint (29)
Shown connected to the other end of the pressurized hose (33)
Not supplied from the above-ground pressurizing device.

Above and below the load meter (13), the load meter (13) is inserted into the shear key grooves (15a) and (15b) of the upper shear grooved retention tube (23) and the lower shear grooved retention tube (25). ) Is provided with a shear key (14a) (14b), and a taper shaft piston (27) for internally moving a taper surface (26) engaged with the shear key from below is operated. Cylinder part (2
8) was provided inside the pressure measuring device.

The shear key grooves (15a) (15) (15) of the load cell (13) sandwiching the thrust portion (16) of the upper shear grooved holding tube (23) and the lower shear grooved holding tube (25).
The connection to b) is a tapered shaft piston section (27)
The shear key groove (14a) (14b) of the shear key (14a) (14b) pushed out by the change in the diameter of the piston part (27) accompanying the movement of the tapered surface (26) pushed down by the pressurized fluid supplied to the cylinder part (28). 15a)
(15b). The pressurized fluid to the cylinder part (28) is supplied from a not-shown above-ground pressurization device connected to the other end of the pressure hose (33) connected to the cylinder pressure hose joint (30). . As the tapered surface (26) is depressed, the spring (32) at the lower end thereof is compressed.
8) With the decompression of the pressurized fluid inside, the spring (32)
Pushes the taper shaft upward, and at the same time, the shearing keys (14a) (14b) are brought into the shearing key groove (15a) by a return member (31) such as a ring spring or an O-ring attached to the shearing keys (14a) (14b). ) (15
Deviates from b).

The shear key (14a) (14)
The other end of the signal cable (35) of the load cell (13), which is sandwiched between b), is pulled out from the cable draw-out joint (34) through the through-hole pipe to the ground, and is sent to a measuring device (not shown) on the ground. Connected and measured.

[0023]Operating procedure  1. At the end of the drilling rod (3), a keyed coupling (2
Insert the drilling tools with 1) into the borehole pipe (1)
And the cutting hole at the end of the hole / load transfer tube (100)
Bit join at the upper end of bit (4) attached to the menu
(22).

2. The rotation and thrust of a drilling tool for drilling and inserting a borehole / load transmission pipe (100) connected to the borehole pipe (1) and the lower end of the borehole pipe (1) in a predetermined search are shown. Not added by aboveground boring equipment.

3. The circulating water, which is supplied around the bit at the time of drilling / insertion to cool the bit and remove cutting earth and sand, is supplied from a circulating water pump (not shown) to the inner space of the drilling rod (3) or a retaining pipe. The water is supplied from the inner space of (1), and the inner hole of the hole (1) (when circulating water is sent from the inner hole of the drilling rod (3)) or the inner space of the rod (the hole (1)). ) When circulating water is sent from the inner space, the water is discharged to the ground.

4. After installing the borehole pipe (1) and the borehole / load transmission pipe (100) connected to the lower end of the borehole pipe (1) at a predetermined location, the drilling tools are separated from the bit joint (22) and placed on the ground. Pull up.

5. The pressure measuring device is connected to the insertion rod (17) and inserted into the hole tube (1).

6. A pressurized liquid is injected by a pressurizing device for shear key operation on the above-ground portion (not shown), and the shear key (1
4a) (14b) to shear key groove (15a) (15b)
And load cell (13) with hole and load transmission tube (10).
0).

7. A pressurized fluid is sent to a pressurizing cell (8) of a pressurizing and measuring device by a pressurizing cell pressurizing device (not shown) in the above-ground section, and is expanded at a predetermined pressure to form a through hole pipe (25) with a lower shear groove. The roughened portion (9) is brought into close contact with the hole wall, and is further pressurized stepwise or at a constant injection amount. At this time, the injection amount together with the injection pressure of the pressurized fluid is measured by a measurement mechanism of a pressurizing cell pressurizing device in the above-ground portion (not shown).

8. In the shear test on the hole wall, the concave and convex processed portion (9) of the holed pipe (25) with the lower shear groove is brought into close contact with the hole wall at a predetermined pressure, and then the above-mentioned ground portion (not shown) is maintained. Perforated pipe (1)
The hole tube (1) is lifted by a lifting device, and the lifting load detected by the load meter (13) of the pressure measuring device during the lifting process is measured by a measuring device (not shown) on the ground. At this time, the displacement of the insertion rod (17) at the upper end of the insertion rod (17) is measured by the displacement measuring device (not shown) (the amount of axial movement of the concave / convex processing portion (9) of the holed pipe (25) with a lower shear groove). Is measured).

9. The measured pressurized cell pressure, the fluid injection amount into the pressurized cell, the lifting load of the concave and convex processed portion (9) of the lower shear grooved holding tube (25), and the coaxial displacement are corrected with the following corrections. Obtain the physical properties of the wall. Pressure applied to the hole wall: Ph Ph = Pcmv-Piv Ph: pressure applied to the hole wall Pcmv: pressure applied to the pressurized cell (injection amount V of liquid injected into the pressurized cell at the time of pressurizing Pcmv) Piv: Pressure required for inflation of the inflatable membrane of the pressurized cell and the uneven portion at the liquid injection amount V ・ Resisting friction of the outer peripheral surface of the uneven portion at the pressure Ph applied to the hole wall: τ τ = T / A τ: unevenness The maximum value of the frictional resistance of the outer peripheral surface of the processed portion T: The maximum value of the pulling load of the uneven processed portion A: The outer peripheral area of the uneven processed portion

10. FIG. 8 shows an example of a test result by the device of the present invention.

[0033]

According to the existing in-situ loading test and friction / shear test technology for the borehole wall, In the method of setting the probe after boring, the ground of the hole wall is easily disturbed due to release of the ground pressure, scouring of the hole wall by the circulating fluid, etc., and it is difficult to apply the method to the collapsible ground. 2. The self-boring method requires advanced drilling and sample manipulation techniques, and reduces work efficiency. There are problems such as.

Although the present apparatus has a mechanism for making the probe diameter slightly smaller than the drill bit diameter in order to facilitate the insertion of the probe, the release of the earth pressure cannot be said to be negligible. The following effects can be expected by using a mechanism that integrates the test equipment installed in the pit with the borehole pipe and drilling tools. 1. By processing the circulating fluid in the borehole, disturbance due to scouring of the hole wall is small, and ground information with higher accuracy can be obtained as compared with the conventional pre-boring method. 2. Since the cell and the borehole can be inserted at the same time as drilling, ground information with sufficient accuracy in design practice can be obtained even on rubble ground or collapsible ground where it is difficult to sample without disturbance. 3. By reducing the peripheral surface resistance associated with cell insertion, the boring equipment adopts the usual inspection equipment, and it is possible to perform drilling and testing continuously, equivalent to the conventional pre-boring method The above work efficiency can be expected.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which a borehole pipe, a test device part integrated with the borehole pipe, and a drilling tool in the present invention are mounted.

FIG. 2 is an explanatory view showing a state at the time of a test in which a pressurization measuring device is provided in a well tube according to the present invention.

FIG. 3 is a side view showing a cross section of a main part of the hole retaining / load transmitting pipe in the embodiment of the present invention.

FIG. 4 is a side sectional view of a drilling tool according to an embodiment of the present invention.

FIG. 5 is a side view showing a cross section of a main part of a combination of a hole retaining / load transmission tube and a drilling tool according to an embodiment of the present invention.

FIGS. 6A and 6B show a pressure measuring device according to an embodiment of the present invention, wherein FIG. 6A is a sectional side view of the device, and FIG. 6B is an explanatory diagram showing a route of a signal cable of a load cell.

FIG. 7 is a side view showing a cross section of a main part in a state where the hole retaining / load transmission tube and the pressure measuring device in the embodiment of the present invention are combined.

FIG. 8 shows an example of a test result using the apparatus of the present invention, and is a curve showing a relationship between a frictional strength and an amount of shear displacement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hole pipe 3 Drilling rod 4 Bit 6 Slit 8 Pressure cell 9 Unevenness processing part 13 Load cell 14a, 14b Shear key 15a, 15b Shear key groove 16 Thrust part 17 Insert rod 18 Cutting shoe 23 Upper hole with upper shear groove Pipe 25 Lower Shear Groove Retaining Pipe 26 Tapered Surface 27 Tapered Shaft Piston 31 Return Material (Ring Spring or O-Ring) 32 Spring 33 Pressurized Hose 34 Cable Pull-Out Joint 35 Signal Cable 36 Expansion Film 37 Expansion Film Fixing Ring 38 Addition Pressure cell core pipe 39 Pressurized liquid circuit

Claims (3)

[Claims] At the same time, when drilling a hole in the ground, a hole wall pressurizing pipe connected to a lower end of the hole wall pressurizing pipe is inserted at a predetermined depth and installed at a predetermined depth. A horizontal loading test is performed in the hole by inflating the hole wall and bringing the hole wall into close contact with the hole wall. An in-hole loading test method characterized by performing a test. 2. A cutting shoe is provided at a lower end, a hole wall pressing portion having a plurality of axial slits formed in a circumferential direction is provided on an outer peripheral surface, and a drill bit is rotatably mounted inside the lower end. A lower hole pipe, a hole / load transmission pipe composed of an upper hole pipe loosely connected to the lower pipe, a hole pipe connected to the lower end of the hole / load transmission pipe, The ground is drilled and drilled into the drilling bit by inserting the tip into the drilling / load transmission pipe and removably connecting the tip to the drill bit, and transmitting the thrust and rotational force to the drill bit. A drilling rod for placing the pipe at a predetermined depth, and an insertion rod are inserted into the borehole pipe and the borehole / load transmission pipe, and the hole is pressed by pressing the hole wall pressing portion of the lower borehole pipe from the inside. A pressure cell is provided to swell the pressure portion to make close contact with the hole wall, and engage with the lower hole tube. An existing lower connecting member was provided, an upper connecting member capable of being engaged with the upper hole tube was provided, and an axial load meter was attached between the installation portion of the lower connecting member and the installation portion of the upper connecting member. A functional borehole-type in-hole loading test device, comprising a pressure measurement device. 3. An upper retaining hole in which the upper connecting member and the lower connecting member of the pressure measuring device protrude in the radial direction by engaging with a tapered surface of a tapered shaft piston that moves up and down inside the pressure measuring device. 3. The functional hole-loading test device according to claim 2, wherein the shear key member is a biased inward member whose tip portion is loosely fitted into a key groove formed on the inner surface of the tube and the inner surface of the lower hole tube. .