JP7780146B2 - Test equipment and test method for confirming the effectiveness of ground improvement - Google Patents

Description

The present invention relates to a testing device and testing method for verifying the effectiveness of ground improvement using chemical injection methods, which involve injecting chemical or cement-based injection materials into the ground with the primary purpose of preventing liquefaction.

In a previous application (Patent Document 1), the applicant proposed a new method for confirming the effectiveness of ground improvement using a chemical grouting method. Specifically, after ground improvement, a small dynamic cone penetration test was used to obtain a depth distribution map of Nd values showing the relationship between depth and Nd values, and a primary confirmation of the effectiveness of the ground improvement was performed based on the increase in the Nd values before and after the ground improvement.
If the ground improvement effect is not confirmed by the primary effect confirmation, electrical logging is performed by inserting a measurement probe equipped with an electrode into the penetration hole of the small dynamic cone penetration test to measure the resistivity, and a resistivity depth distribution map showing the relationship between depth and resistivity is obtained, and a secondary effect confirmation is performed to confirm the ground improvement effect from the decrease in resistivity before and after the ground improvement.

Japanese Patent Application Laid-Open No. 2021-4473

However, the measurement method described in Patent Document 1 involves a dynamic cone penetration test in which a cone attached to the tip of a rod is penetrated by hammering, then the cone is completely removed and a measurement probe for electrical logging is then pressed into the same penetration hole using a press-in device.This means that the equipment needs to be installed twice - first, the equipment for penetrating the tip of the cone in the dynamic cone penetration test is installed, and then the press-in device for pressing in the measurement probe for electrical logging is installed.This requires a lot of time to re-install the equipment, resulting in poor measurement efficiency.

In addition, the press-in device used to press in measurement probes for electrical logging requires a significant amount of time to set up the reaction mount and anchors, and depending on the geology of the target ground, it may be necessary to prepare separate reaction weights, which also poses challenges to measurement efficiency.

Furthermore, electrical logging requires that the electrodes attached to the periphery of the measurement probe be in reliable contact with the borehole wall, but the electrodes often do not make good contact with the borehole wall, resulting in poor contact and a decrease in measurement accuracy. In Patent Document 1, a contact-promoting protrusion that protrudes outward is provided on the opposite side of the electrode to ensure that the outer electrode contacts the borehole wall when inserted into the penetration hole. However, when the measurement probe is pressed into place using the pressing device, this contact-promoting protrusion often comes into contact with the borehole wall and is worn and damaged, posing issues with its reusability.

The primary objective of this invention is to provide a testing device and testing method that improves measurement efficiency and measurement accuracy for confirming the effectiveness of ground improvement.

In order to solve the above problem, the present invention according to claim 1 provides a test device for confirming the effect of ground improvement,
The test device includes a measurement probe at the tip of a penetration rod that penetrates into the ground,
The measurement probe has a tip cone used for a dynamic cone penetration test at its tip, and an electrode unit equipped with an electrode used for electrical logging at an upper portion of the tip cone,
A test device for confirming the effect of ground improvement is provided, characterized in that an eccentric flange portion is provided at a circumferential position opposite to the circumferential position at which the electrode is arranged, which protrudes radially outward from the outer diameter of the electrode portion and does not protrude from the outer diameter of the tip cone.

In the invention described in claim 1 above, the measurement probe provided in the testing equipment has a tip cone used for dynamic cone penetration testing at its tip, and an electrode section equipped with an electrode used for electrical logging at the top of the tip cone. This makes it possible to conduct electrical logging while withdrawing the measurement probe that has penetrated the ground after conducting the dynamic cone penetration test. Therefore, the two press-in steps required in the past, where the rod is withdrawn after the dynamic cone penetration test and the measurement probe for electrical logging is inserted, are eliminated. Instead, both the dynamic cone penetration test and electrical logging can be performed in the process of inserting and withdrawing the measurement probe once, significantly improving measurement efficiency.

The measurement probe also has an eccentric flange at a circumferential position opposite the circumferential position where the electrode is located. The flange protrudes radially outward beyond the outer diameter of the electrode but does not protrude beyond the outer diameter of the tip cone. Therefore, after a dynamic cone penetration test, when electrical logging is performed while the measurement probe is being withdrawn, the eccentric flange comes into contact with the hole wall of the penetration hole, scraping away the natural ground on the hole wall, causing sediment to accumulate on top of the eccentric flange, which acts to push the measurement probe toward the side opposite the eccentric flange. This makes it easier for the electrode to come into contact with the hole wall, thereby improving the measurement accuracy of electrical logging.

The present invention, according to claim 2, provides a test device for confirming the effectiveness of ground improvement described in claim 1, in which the tip cone is configured to come off the measurement probe when the measurement probe is pulled out.

In the invention described in claim 2 above, when electrical logging is performed while the measurement probe is being withdrawn, the tip cone, which is formed with a larger diameter than the electrode portion to reduce contact resistance during dynamic cone penetration testing, is removed from the measurement probe, making it easier for the electrode portion's electrode to contact the borehole wall, further improving measurement accuracy.

The present invention, according to claim 3, provides a test device for confirming the effect of ground improvement as described in either claim 1 or 2, in which the tip cone is fitted onto the measurement probe body extending from the penetration rod, and is fitted onto an eccentric spacer with a flange having the eccentric flange at its base end.

In the invention described in claim 3 above, when the tip cone is attached to the tip of the measurement probe, the tip cone is fitted onto the measurement probe body extending from the penetration rod, and is fitted onto a flanged eccentric spacer having the eccentric flange at its base end. Because the eccentric flange is attached to the flanged eccentric spacer, if the eccentric flange is worn or damaged, the flanged eccentric spacer can be replaced and the eccentric flange can be reused any number of times.

As a fourth aspect of the present invention, there is provided a test device for confirming the effectiveness of ground improvement described in claim 3, in which the inner surface of the flanged eccentric spacer is provided with a positioning protrusion that fits into a notch provided on the outer surface of the measurement probe body.

In the invention described in claim 4 above, to ensure that the eccentric flange provided on the flanged eccentric spacer is positioned at a circumferential position opposite the circumferential position at which the electrodes of the electrode unit are positioned, a positioning notch and a protrusion that fits into this are provided on the inner surface of the flanged eccentric spacer and the outer surface of the measurement probe body, respectively.

The present invention, according to claim 5, provides a test device for confirming the effectiveness of ground improvement described in any one of claims 1 to 4, in which the electrode portion is an outer sleeve equipped with an electrode fitted onto the measurement probe body extending from the penetration rod.

In the invention described in claim 5 above, by providing the measurement probe body, the impact energy of the penetration rod can be reliably transmitted to the tip cone through the measurement probe body during a dynamic cone penetration test. Furthermore, by encasing the measurement probe body in an exterior sleeve, the measurement probe can be easily withdrawn during electrical logging.

The present invention, according to claim 6, provides a test device for confirming the effect of ground improvement as described in claim 5, in which the outer sleeve is fixed in its circumferential rotation by its fitting portion fitting into a circumferential fixing protrusion provided on the circumferential surface of the measurement probe body.

In the invention described in claim 6 above, when the outer sleeve is attached to the measurement probe body, in order to align the electrodes of the electrode unit body with the electrodes of the outer sleeve and to prevent relative circumferential rotation between the measurement probe body and the outer sleeve, circumferential fixing convex portions provided on the circumferential surface of the measurement probe body engage with fitting portions provided on the outer sleeve, thereby preventing circumferential rotation of the outer sleeve.

According to a seventh aspect of the present invention, there is provided a test method for confirming a ground improvement effect using the test device according to any one of the first to sixth aspects,
A test method for confirming the effectiveness of ground improvement is provided, which is characterized by conducting a dynamic cone penetration test in which the tip cone is driven into the ground by hitting it with a hammer, and then conducting electrical logging while withdrawing the penetrated measurement probe.

The invention described in claim 7 above is a testing method for confirming the effectiveness of ground improvement using the above-mentioned testing device, in which a dynamic cone penetration test is performed by hammer striking, and then electrical logging is performed while the measurement probe is withdrawn. Therefore, with a single penetration of the measurement probe, a dynamic cone penetration test can be performed during penetration and electrical logging can be performed during withdrawal, significantly improving measurement efficiency.

As explained above in detail, the present invention can significantly improve measurement efficiency and measurement accuracy.

1 is a cross-sectional view showing a state in which a dynamic cone penetration test is being performed using the test device 1 according to the present invention. 1 is a cross-sectional view showing a state in which electrical logging is being carried out using the test device 1 according to the present invention. 1A and 1B show a measurement probe 3, in which (A) is a front view and (B) is a side view. FIG. 2 is an exploded view of the measurement probe 3. 1A and 1B show a measurement probe body 8, in which FIG. 1A is a front view and FIG. 1B is a side view. FIG. 2 is an enlarged perspective view of the tip of the measurement probe 3. 10 is a cross-sectional view showing the state of the tip of the measurement probe 3 when it is pulled out of the insertion hole. FIG.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The present invention is a test device 1 for verifying the effectiveness of ground improvement using a chemical grouting method, in which a chemical-based or cement-based ground grouting material, such as water glass (sodium silicate), is injected into the ground to strengthen soft ground, such as reclaimed land.

As shown in Figure 1, the testing device 1 according to the present invention is equipped with a measurement probe 3 that penetrates into the ground at the tip of a penetration rod 2.

Tests using this testing device 1 involve conducting a dynamic cone penetration test to penetrate the measurement probe 3 into the ground, as shown in Figure 1, and then conducting electrical logging when the penetrated measurement probe 3 is withdrawn, as shown in Figure 2.

As shown in Figure 3, the measurement probe 3 has a tip cone 4 at its tip, which is used for dynamic cone penetration testing, and an electrode section 5 equipped with an electrode 6 used for electrical logging, located above the tip cone 4.

The dynamic cone penetration test can be performed using various sounding methods, such as the standard penetration test, Swedish penetration test, ram sounding, and small dynamic cone penetration test. However, large or medium-sized ram sounding (SRS, MRS) is preferred. Furthermore, any known operating method can be used, including fully automatic, semi-automatic, and manual. Therefore, the test device 1 according to the present invention can be used for a variety of ground conditions.

To conduct a dynamic cone penetration test using this testing device 1, as shown in Figure 1, the anvil 20 attached to the penetration rod 2 is struck axially with a hammer 21 with a predetermined striking force, driving the tip cone 4 into the ground and measuring the penetration depth and number of strikes. The tip cone 4 penetrates to the required depth by sequentially adding segments of the penetration rod 2, each segmented to a predetermined length.

The electrical logging uses the electrode 6 attached to the measurement probe 3 to measure the electrical resistance (resistivity) of the surrounding ground to confirm the effectiveness of the ground improvement work. Progress management of improved bodies using the chemical grouting method is generally carried out using the uniaxial compressive strength qu. However, the target strength of the improved body is not particularly high, at around qu = 50 to 100 kPa. This means that there is significant variation in strength due to disturbance caused by sampling and uneven ground conditions, making it difficult to quantitatively grasp changes in properties before and after improvement. Therefore, measuring electrical resistivity is effective in quantitatively grasping property values that are more sensitive than strength.

To perform electrical logging using this test device 1, resistivity measurements are taken during the process of withdrawing the penetration rod 2 using the withdrawal device 22, which is used to withdraw the penetration rod after conducting a dynamic cone penetration test. The withdrawal device 22 can take any form, but an example is one shown in Figure 2, in which pistons 23 that can freely extend and retract in the vertical direction are placed on both sides of the penetration rod 2, and a chuck 25 that clamps the penetration rod 2 is provided in the center of a platform 24 spanning the upper ends of the pistons 23. With the penetration rod 2 held by the chuck 25, the pistons 23 on both sides extend in unison, causing the platform 24 to move upward, thereby withdrawing the measurement probe 3.

The measurement probe 3 will be described in more detail below.
The measurement probe 3 has a rod-like appearance with a substantially circular cross section, and a threaded portion (not shown) is formed at the upper end for connection to the penetration rod 2, so that it can be screwed into the threaded portion provided at the lower end of the penetration rod 2. Also, below the threaded portion is provided an electrode portion 5 in which a plurality of the electrodes 6 are arranged in a row at predetermined circumferential positions along the axial direction at predetermined intervals, and the tip cone 4 is disposed below this electrode portion 5.

As shown in Figure 4, the measurement probe 3 is composed of a measurement probe main body 8 connected to the penetration rod 2, an outer sleeve 9 fitted over the electrode portion 5 of the measurement probe main body 8, a flanged eccentric spacer 10 fitted over the lower end of the measurement probe main body 8, and a tip cone 4 fitted over the flanged eccentric spacer 10.

As shown in Figure 5, the measurement probe body 8 is a rod-shaped member with a roughly circular cross-section made of metal strong enough to transmit the axial impact force input to the penetration rod 2 during a dynamic cone penetration test to the tip cone 4 at the lower end. A hollow section is formed in the axial section from the upper end to at least the section where the electrode 6 is located. A threaded section is formed on the inner surface of the upper end to be threadedly engaged with the penetration rod 2. An electric cable 7 extends from the upper end of the measurement probe body 8 through the hollow section to each electrode 6. The upper end of the electric cable 7 extends to the ground through the hollow section of the penetration rod 2, which has a hollow cylindrical cross-section over its entire length, and its tip is connected to a measuring device and a recording device.

In addition, one or more ring-shaped water-stopping members 11 are provided on the outer periphery of the upper and lower parts of the axial section of the measurement probe body 8 where the electrodes 6 are located, to prevent groundwater and the like from entering the gap between the outer sleeve 9 (Figure 4).

Furthermore, in the axial section of the measurement probe body 8 where the electrode 6 is arranged, a groove is provided along the axial direction and communicating with the hollow section. An insulating member 12 made of an electrically insulating material such as resin is fitted into this groove, and the electrode 6 is fixed to this insulating member 12.

The electrodes 6 may be arranged in a two-pole or three-pole manner, but a four-pole arrangement is preferred. In a four-pole electrode arrangement, as shown in Figures 3 to 5, four electrodes 6 are arranged in a row in the vertical direction (axial direction) at a predetermined interval, with the two electrodes 6A at each end in the vertical direction and the two in the middle being potential electrodes 6V. The center-to-center distance between adjacent electrodes is preferably 2.5 cm. Using the four-pole method has the advantage of eliminating the need for a ground electrode and stabilizing measurement values.

The electrodes 6 are made of a conductive metal material and are provided so as to provide electrical communication from the hollow interior of the measurement probe body 8 to the outer surface of the measurement probe 3. The lower ends of the electrical cables 7 are connected to the hollow interior of the measurement probe body 8.

The electrode section 5 has an outer sleeve 9 fitted onto the measurement probe main body 8 extending from the penetration rod 2, and the outer sleeve 9 has multiple electrodes 6 exposed on its circumferential surface. The electrodes 6 on the outer sleeve 9 are arranged in a row at predetermined intervals along the axial direction, similar to the electrodes 6 on the measurement probe main body 8. When the outer sleeve 9 is attached to the measurement probe main body 8, each electrode 6 on the outer sleeve 9 is electrically connected to the corresponding electrode 6 on the measurement probe main body 8.

The outer sleeve 9 is made of an electrically insulating material such as resin and is a substantially cylindrical member with both axial ends open. As shown in FIG. 3 , when the outer sleeve 9 is inserted into the measurement probe main body 8, its outer diameter is larger than the outer diameter of the measurement probe 3 (measurement probe main body 8) above the electrode portion 5. By making the outer diameter of the outer sleeve 9 larger than the outer diameter of the measurement probe 3 above the electrode portion 5, the electrode 6 exposed on the circumferential surface of the outer sleeve 9 is more likely to come into contact with the hole wall when the measurement probe 3 is pulled out, improving measurement accuracy and reducing damage to the measurement probe 3.

The outer sleeve 9 is prevented from rotating in the circumferential direction relative to the measurement probe main body 8 by fitting a circumferential fixing protrusion 14 provided on the circumferential surface of the measurement probe main body 8 into a fitting portion 15 provided on the outer sleeve 9. The circumferential fixing protrusion 14 is formed in an axially elongated, approximately rectangular or oval shape at the upper end of the electrode portion 5 of the measurement probe main body 8. The fitting portion 15 is formed in a corresponding shape at the upper end of the outer sleeve 9. When the outer sleeve 9 is inserted into the measurement probe main body 8, the fitting portion 15 fits into the circumferential fixing protrusion 14, thereby aligning the electrodes 6 provided on the measurement probe main body 8 and the electrodes 6 provided on the outer sleeve 9 and preventing circumferential rotation of the measurement probe main body 8 and the outer sleeve 9. This prevents misalignment between the electrodes 6 provided on the measurement probe main body 8 and the electrodes 6 provided on the outer sleeve 9 when the measurement probe 3 is inserted or removed.

As shown in Figures 3(B) and 6, the test device 1 according to the present invention has an eccentric flange 16 that protrudes radially outward from the outer diameter of the electrode portion 5 but does not protrude from the outer diameter of the tip cone at a circumferential position opposite the circumferential position at which the electrode 6 of the measurement probe 3 is located. The eccentric flange 16 is a flange-shaped protrusion that protrudes radially outward from the outer diameter of the measurement probe 3 within a predetermined circumferential range centered on the circumferential position opposite the circumferential position at which the electrode 6 is located. Outside of this predetermined circumferential range protruding radially outward from the outer diameter of the measurement probe 3, the eccentric flange 16 is formed to have approximately the same diameter as the outer diameter of the measurement probe 3, making it eccentric with respect to the central axis of the measurement probe 3.

By providing the eccentric flange 16, when electrical logging is performed while the measurement probe 3 is being withdrawn after the dynamic cone penetration test, as shown in Figure 7, the eccentric flange 16 comes into contact with the hole wall of the penetration hole, scraping away the natural ground on the hole wall surface and causing sediment to accumulate on top of the eccentric flange 16, which acts to push the measurement probe 3 to the side opposite the eccentric flange 16. This makes it easier for the electrode 6 provided on the side opposite the eccentric flange 16 to come into contact with the hole wall, thereby improving the measurement accuracy of electrical logging.

As mentioned above, to ensure that sediment accumulation on top of the eccentric flange 16 pushes the measurement probe 3 toward the electrode 6, it is preferable to locate the eccentric flange 16 below the section in which the electrode 6 is located. In the illustrated example, the eccentric flange 16 is located immediately below the outer sleeve 9 that includes the electrode 6, between it and the tip cone 4.

As shown in Figures 3(B) and 6, the eccentric flange 16 is preferably formed with a cross-sectional slope that gradually widens radially outward from the outer diameter of the outer sleeve 9 downward. By forming the eccentric flange 16 with such a shouldered cross-sectional shape, contact resistance with the hole wall can be reduced when the measurement probe 3 is pulled out, and soil that has accumulated on top of the eccentric flange 16 can be appropriately removed toward the hole wall without excessive accumulation, allowing for a smooth pulling-out operation.

The circumferential range in which the eccentric flange 16 is provided is preferably between 1/3 and 2/3, and particularly between 1/3 and 1/2, of the circumference, centered on the circumferential position opposite the circumferential position in which the electrode 6 is located. If it is less than 1/3, the effect of sediment accumulating on the eccentric flange 16 in pushing the measurement probe 3 toward the electrode 6 will be small. If it is more than 2/3, there is a risk that the resistance to pulling out the measurement probe 3 will be large.

The eccentric flange 16 protrudes radially outward from the outer diameter of the electrode portion 5, to the extent that it does not protrude radially outward from the outer diameter of the tip cone 4, so as not to create resistance during a dynamic cone penetration test. To achieve this, the central axis of the outer diameter of the part of the flanged eccentric spacer 10 where the tip cone 4 is mounted may be offset from the central axis of the inner diameter, thereby positioning the central axis of the tip cone 4 eccentrically from the central axis of the measurement probe main body 8. This positions the central axis of the tip cone 4 slightly offset from the central axis of the measurement probe main body 8, on the opposite circumferential side from the position where the electrode 6 is located.

As shown in Figure 4, the eccentric flange 16 is provided at the base end of the flanged eccentric spacer 10 onto which the tip cone 4 is fitted. In other words, the tip cone 4 is fitted onto the measurement probe body 8 extending from the penetration rod 2, and is fitted onto the flanged eccentric spacer 10, which has the eccentric flange 14 at its base end.

The flanged eccentric spacer 10 is a sleeve-like member made of resin or metal, formed in a generally cylindrical shape with both axial ends open, and with the flange-like eccentric flange 16 formed at the upper end (base end). The flanged eccentric spacer 10 is fitted to the lower end of the measurement probe body 8. The flanged eccentric spacer 10 is fixed to the measurement probe body 8 by a non-detachable fixing means so that it does not fall off the measurement probe body 8 when the measurement probe 3 is inserted or removed. Such fixing means include welding, or mechanical element connection to the measurement probe body 8 using screws, pins, rivets, etc.

The inner surface of the flanged eccentric spacer 10 is provided with a positioning protrusion (not shown) that fits into a notch 17 (Figure 5) provided on the outer surface of the measurement probe body 8. By fitting this positioning protrusion into the notch 17, the eccentric flange 16 provided on the flanged eccentric spacer 10 is positioned on the opposite side of the circumferential position of the electrode 6.

The tip cone 4 is fitted onto the flanged eccentric spacer 10 from the tip side. The tip cone 4 is not fixed to the flanged eccentric spacer 10 and is configured to come off the measurement probe 3 when the measurement probe 3 is withdrawn. The tip cone 4 is formed with an outer diameter larger than the outer diameter of the outer sleeve 9 and the eccentric flange 14. Therefore, when performing electrical logging while withdrawing the measurement probe 3, having the tip cone 4 attached may make it difficult for the electrode 6 attached to the outer sleeve 9 to contact the borehole wall. Therefore, it is recommended that the tip cone 4 be left at the bottom of the borehole after the dynamic cone penetration test is completed.

The tip cone 4 is shaped and sized to comply with the regulations for various dynamic cone penetration tests. The tip cone 4 has an outer diameter larger than the outer diameter of the measurement probe 3 above it, and is configured so that the portion of the measurement probe 3 above the tip cone 4 does not come into contact with the wall of the penetration hole formed by the tip cone 4 during a dynamic cone penetration test.

As shown in Figure 4, the measurement probe 3 is assembled by attaching the electrode 6 and electrical cable 7, and then inserting the outer sleeve 9 and flanged eccentric spacer 10, in that order, from the bottom end into the measurement probe body 8, which has a water-stopping member 11 attached. The flanged eccentric spacer 10 is then fixed to the measurement probe body 8, and finally, the tip cone 4 is fitted onto the flanged eccentric spacer 10 to complete the assembly.

To conduct a test to confirm the effectiveness of ground improvement using the test device 1 configured as described above, as shown in Figure 1, a dynamic cone penetration test is performed in which the tip cone 4 is driven into the ground by striking with a hammer 21 while the penetration rod 2 and electrical cable 7 are sequentially added. Then, as shown in Figure 2, electrical logging is performed while the measurement probe 3 driven in by the dynamic cone penetration test is extracted by an extraction device 22. In this way, electrical logging can be performed when the measurement probe 3 driven in by the dynamic cone penetration test is extracted, significantly reducing the effort required to relocate equipment and improving measurement efficiency. Furthermore, there is no need to install a press-in device to press in the measurement probe for electrical logging, and there is no need to prepare a weight for reaction force, which also improves measurement efficiency.

The effectiveness of ground improvement is confirmed by using the test device 1 to conduct dynamic cone penetration tests and electrical logging before and after ground improvement, and comparing the depth distribution maps of N values or Nd values before and after ground improvement obtained by the dynamic cone penetration tests with the decrease in resistivity before and after ground improvement obtained by electrical logging.

1...Testing device, 2...Penetration rod, 3...Measurement probe, 4...Tip cone, 5...Electrode portion, 6...Electrode, 7...Electrical cable, 8...Measurement probe body, 9...Outer sleeve, 10...Eccentric spacer with flange, 11...Water-stopping member, 12...Insulating member, 14...Circumferential fixing protrusion, 15...Fitting portion, 16...Eccentric flange, 17...Notch

Claims (7)

A test device for confirming the effect of ground improvement,
The test device includes a measurement probe at the tip of a penetration rod that penetrates into the ground,
The measurement probe has a tip cone used for a dynamic cone penetration test at its tip, and an electrode unit equipped with an electrode used for electrical logging at an upper portion of the tip cone,
A test device for confirming the effectiveness of ground improvement, characterized in that an eccentric flange portion is provided at a circumferential position opposite to the circumferential position at which the electrode is arranged, which protrudes radially outward from the outer diameter of the electrode portion and does not protrude from the outer diameter of the tip cone. A test device for confirming the effectiveness of ground improvement as described in claim 1, wherein the tip cone is configured to detach from the measurement probe when the measurement probe is pulled out. A test device for confirming the effectiveness of ground improvement as described in either claim 1 or 2, wherein the tip cone is fitted onto the measurement probe body extending from the penetration rod, and is fitted onto an eccentric spacer with a flange, the eccentric flange being provided at the base end. A test device for confirming the effectiveness of ground improvement as described in claim 3, wherein the inner surface of the flanged eccentric spacer is provided with a positioning protrusion that fits into a notch provided on the outer surface of the measurement probe body. A test device for confirming the effectiveness of ground improvement described in any one of claims 1 to 4, wherein the electrode portion comprises an outer sleeve equipped with an electrode fitted onto the measurement probe body extending from the penetration rod. A test device for confirming the effectiveness of ground improvement as described in claim 5, wherein the outer sleeve is fixed in its circumferential rotation by its fitting portion fitting into a circumferential fixing protrusion provided on the circumferential surface of the measurement probe body. A test method for confirming the effect of ground improvement using the test device according to any one of claims 1 to 6,
A test method for confirming the effectiveness of ground improvement, characterized by conducting a dynamic cone penetration test in which the tip cone is driven into the ground by striking it with a hammer, and then conducting electrical logging while withdrawing the penetrated measurement probe.