JP2018017522A - Method for evaluating effect of improvement treatment on cracked rock and probe for rock under improvement treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for quantitatively evaluating the effect of an improvement treatment on cracked rock and a probe for rock under an improvement treatment.SOLUTION: The present invention includes: a body 2 having a contact part on each side; drooping means 24 for drooping the body into a borehole; a striking mechanism 28 connected to the body for striking a hole surface of the borehole; and a rigid expansion mechanism S which is expandable from one contact part to the other contact part of the body and exhibits rigidity at least when the striking mechanism strikes the hole surface, the rigid expansion mechanism including a vibration sensor 18.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for evaluating the effect of improvement processing of a rock having cracks, and a probe for the improved processing rock.

When excavating a bedrock layer containing an inclined crack and retaining both sides of the excavation site, depending on the direction of the crack and the degree of inclination, one of the excavation sites may become a flow bed and collapse.
In order to avoid such inconveniences, the present applicant has previously filed a patent application as Japanese Patent Application No. 2015-218766 (hereinafter referred to as “prior application”) for the invention of “the construction method of the rock retaining structure of the rock layer and the retaining structure” doing.
This mountain retaining structure is improved, for example, by the grouting method in the rock bed excavation part 104 of FIG. 1 where the side of the easy-to-collapse bed (the inclination angle of the crack in the direction of the slope collapse is larger than the internal frictional force of the crack part). It is. However, when the grout is not sufficiently filled into the crack due to some cause (for example, the soft viscous soil intervening in the crack remains as an inclusion after grouting), the safety of construction cannot be ensured.
Therefore, when improving the bedrock bedrock by grouting and constructing a retaining structure, quantitatively evaluate the degree of change (increase) in the deformation coefficient of the cracked part of the bedrock before and after the improvement. It is desirable to confirm.

As a conventional technique, there is a method for investigating defects in concrete by striking concrete in general, which measures and analyzes the state of propagation / attenuation of impact energy using sound waves and explores defects inside the concrete. (Patent Document 1).
On the other hand, as a technology related to ground improvement, a rubber tube having a height of about 50 cm is inserted into the bore hole shown in FIG. 9 (A) and water is injected into the bore, and the deformation coefficient is determined from the relationship between the hole diameter and load strength. What is to be evaluated is known (Non-Patent Document 1).
A method is also known in which a horizontal loading test in a hole using this device is performed to compare the deformation coefficients before and after grouting (Non-patent Document 2). In the CL grade rock mass, it is known that the deformation coefficient obtained by the in-hole horizontal loading test increases after grouting (see FIG. 9B). In homogeneous in-situ rock, the strength increases by an amount equivalent to [burden load x tanφ] as the depth increases, so the yield stress obtained in the borehole loading test increases linearly as the depth increases. To go.
A method for evaluating the adhesive strength c and the internal friction angle φ of the rock using this relationship has also been proposed (Non-patent Document 3).

JP2003-014709

“In-hole horizontal loading test” (JGS1421-2003) "Examination of mechanical improvement effect by grouting using in-hole loading test machine -for sandstone and shale alternate layer-" No.21, pp.44-52, 1966.3 “Consideration of c and φ of in situ rock mass required by in-hole loading test” (co-authored by Toshiaki Takeuchi and Ikuo Suzuki), Annual Report of Applied Geological Survey Office, No.2, pp.107-114, 1980.

Patent Document 1 is a technique for finding a defect in a concrete structure, and it is not known how much the state of the crack portion has been improved before and after the improvement process.
In Non-Patent Document 1, changes before and after improvement can be quantitatively measured as changes in the deformation coefficient of the rock mass.
However, in this method, the rubber tube has a certain vertical length. For example, when the hole diameter of the borehole is about 46 mm, the rubber tube is vertically long as shown in FIG. 9A, and the average deformation coefficient of the rock portion within this vertical length is measured. Value.
On the other hand, the rock generally has many cracks, and the width of the crack portion is generally as small as several millimeters. Therefore, the range of the vertical length includes both the crack portion and the healthy portion. Therefore, a larger range than the crack portion itself is evaluated, and the deformation coefficient of the crack portion itself cannot be evaluated.

A first object of the present invention is to provide a method and a probe for an improved processing rock mass which can quantitatively evaluate the effect of the improvement processing of a rock mass including a crack.
The second object of the present invention is to vibrate the rock portions above and below the improved crack mark and detect vibrations from these rock portions so that the soundness of the crack can be accurately determined.
A third object of the present invention is to provide an improved rock mass explorer having a non-bulky structure suitable for detecting vibration from the rock mass portion of the above-described improved crack mark.

The first means is
A method for evaluating the effect of improvement treatment of a rock mass having a crack by a change in a deformation coefficient near the crack,
A step of forming a borehole in the rock so as to cut through the crack marks by the improvement process;
Throwing a probe with contact portions at both ends of the main body into the boring;
Contacting one contact portion with a rock portion above one crack mark, and contacting the other contact portion with a rock portion under one crack mark,
Striking the hole surface of the boring hole above or below the crack mark in a state of contacting both rock portions through the contact portion;
Detecting the vibration of the spacecraft due to the hitting with a vibration sensor provided in a proper position of the spacecraft,
Comprising
The rigidity of at least the contact portion of the probe is larger than the rigidity of the rock mass,
The signal observed by the observation device is compared with the standard signal when the improvement process is appropriate to determine whether the effect of the improvement process is appropriate.

  This measure proposes a method to evaluate the effect of the improvement process of rocks with cracks by the change of deformation coefficient near the cracks. In order to evaluate the change of the deformation coefficient, as shown in FIG. 1, a borehole 108 is drilled in the flow bed portion of the rock 100 adjacent to the excavation part, and both sides of the spacecraft 1 inserted into the borehole 108. This is performed by striking the hole surface of the borehole 108 with the striking mechanism 28 of the probe 1 in a state in which the contact portion is in contact with the upper and lower sides of the crack mark 102a. Since the crack change coefficient is the object of observation, the effect of crack improvement can be evaluated more appropriately.

The “crack mark” is a mark of a crack appearing in the hole surface of the boring hole 108 that vertically cuts through the crack, and includes a part that has been properly cured by grouting and that is still insufficiently cured and remains flexible.
“Contact part”: It is a contact part with the rock, and is preferably made of a material having at least a rigidity higher than that of the rock, and is preferably brought into contact with the rock without using a soft material such as rubber. Further, in the preferred illustrated example, the vertical lengths of the contact portions E ₁ and E ₂ are made smaller than the hole diameter of the boring hole 108.

The second means has the first means, and the crack in the rock before the improvement is inclined,
One contact part that contacts the upper side of the crack mark is positioned on the lower side of the crack inclination direction, and the other contact part that contacts the lower side of the crack mark is positioned on the upper side of the crack inclination direction. Adjust the orientation of the spacecraft.

In this means, the lower side of the inclined direction of the crack which is inclined as shown in FIG. 4, the first contact portion E ₁ of the spacecraft above the crack trail 102a abuts the upper inclined direction of the crack, the crack trail the second contact portion E ₂ of the spacecraft below 102a is so as to abut, and adjust the orientation of the spacecraft. Thereby, a spacecraft can be positioned stably. In a preferred illustrated example, the two contact portions E ₁ are between the lowest height H2 at which the upper surface SU of the crack 102 appears in the hole surface and the highest height H1 at which the lower surface SL of the crack 102 appears in the hole surface. , are arranged _{E 2.}

The third means is a probe for improved processing rock,
A body having contact portions on both sides;
Drooping means for dripping this body into the borehole;
A striking mechanism connected to the main body for striking the hole surface of the boring hole;
With
It has a rigid expansion and contraction mechanism that can expand and contract from one contact part of the main body to the other contact part and exhibits rigidity at the time of hitting by at least the hitting mechanism,
A vibration sensor is provided in a part of this rigid expansion / contraction mechanism.

In this measure, we propose a spacecraft for improved processing. The searcher includes a main body 2 having a pair of contact portions E ₁ and E ₂ on both sides. A rigid expansion / contraction mechanism S, which is a vibrating body extending from the first contact portion E ₁ to the second contact portion E ₂ , is provided, and the main body 2 of the spacecraft 1 is suspended into the boring hole 108 via the drooping means 24. In the vicinity of the crack mark 102a, the two contact portions E ₁ and E ₂ are provided so as to protrude outward and come into contact with the inner surface of the boring hole 108. In this state, the striking mechanism 28 connected to the main body 2 strikes the inner surface of the boring hole 108, and vibration due to the striking is detected by the vibration sensor 18 provided in a part of the rigid expansion / contraction mechanism S.

The “main body” has contact portions E ₁ and E ₂ on both sides. While the conventional apparatus shown in FIG. 9 is vertically long in the vertical direction, it is preferable that the main body of the improved processing rock explorer of the present invention has a horizontally long shape. It is because it is suitable for evaluating the soundness of a crack location locally by it.
The “rigid extension / contraction mechanism” continuously extends and contracts between the two contact portions, and exhibits rigidity to the extent that rigidity can be exhibited at least during a striking operation.
The expansion / contraction means may be a gear type (gear box), a cam type, or the like, but in a preferred illustrated example, a pneumatic type (air cylinder +) is used to prevent the main body 2 from becoming bulky. A plunger is used. The pneumatic expansion / contraction means is configured to be in close contact with the boring hole at the time of hitting the boring hole, and to transmit the vibration of the rock mass above and below the crack mark 102 a to the vibration sensor 18.
The rigid expansion / contraction mechanism preferably has a structure that does not use a flexible material that absorbs vibration, such as a rubber cushion, at a position where vibration is transmitted.
The “dripping means” may be a drooping rod, but the drooping wire in the illustrated example is convenient and suitable for handling. The drooping rod is considered to be able to adjust the orientation of the main body more precisely, but a certain amount of orientation error is allowed for the purpose of measuring the deformation coefficient of the crack mark 102a.

The fourth means includes the third means, and means for adjusting the orientation of the main body with respect to the circumferential direction of the boring hole.

In this means, the orientation of the main body 2 with respect to the circumferential direction of the boring hole 108 can be adjusted. Thus, it is possible to appropriately select the contact points of the hole surface of the borehole 108 and the contact portion E _1, E _2.
The “direction of the main body” means the direction of the horizontal direction of the main body or the direction connecting the two locations where the main body contacts the hole surface of the boring hole 108.
“The means for adjusting the orientation of the main body is taken” is limited to the case where the main body orientation adjusting means has its own mechanism (for example, a device that changes the orientation of the main body with respect to the aforementioned hanging rod). In other words, it means that it is sufficient if the entire searcher has a structure suitable for adjusting the orientation of the main body 2. In the preferred illustrated example, as the drooping means 24, two wires 25 suspended from the ground are connected to both sides in the longitudinal direction of the main body 2, and the support positions of the two wires on the ground side are arranged in the circumferential direction of the boring hole. By changing the position, the position of the main body can be adjusted. That is, in the illustrated example, the drooping means 24 also serves as the main body orientation adjusting means T.
A crack position confirmation device 20 that can confirm the height of the crack mark 102a over at least a certain range in the circumferential direction (preferably the entire circumference in the circumferential direction) of the bore surface of the boring hole 108 together with the body orientation adjusting means T. It is desirable that the operator can adjust the orientation of the main body 2 while checking the position of the crack on the ground. A preferred example of the crack position confirmation device 20 is a borehole camera.

According to the first aspect of the invention, since the vibration of the spacecraft that comes into contact with the rock portion above and below the crack mark via the contact portion is detected, the quality of the crack mark improvement process can be accurately determined.
According to the invention relating to the second means, by adjusting the direction of the spacecraft and the direction in which the crack is inclined, the two contact portions can be installed on the upper side and the lower side so as to sandwich the crack. Thus, it is possible to obtain a highly reliable search result by performing a search with an appropriate contact.
According to the third aspect of the invention, there is provided a rigid expansion / contraction mechanism capable of expanding and contracting from one contact portion of the main body to the other contact portion and exhibiting rigidity at the time of striking by at least the striking mechanism. Since the vibration sensor is provided in a part of the rock, the vibration of the rock can be accurately detected.
According to the fourth aspect of the invention, since the means for adjusting the orientation of the main body with respect to the circumferential direction of the boring hole is provided, it is possible to obtain a highly reliable search result by searching in a more appropriate direction.

It is a conceptual diagram of the usage example of the spacecraft for improved processing rock according to the present invention. It is sectional drawing of the spacecraft for improved processing rock mass of FIG. It is explanatory drawing which shows the procedure of the method of evaluating the effect of the improvement processing of the rock which has a crack using the spacecraft for improved processing rock of FIG. 2, The figure (A) shows the step which excavates a borehole. Figure (B) shows the stage where the exploration machine for improved rock mass descends in the borehole, Figure (C) shows the stage where the exploration machine for improved rock mass is fixed in the borehole, and Figure (A) shows the stage where the borehole is drilled. The stages of striking with the striking mechanism of the improved processing rock explorer are shown. It is explanatory drawing of the positional relationship of the evaluation method of the effect of the improvement process of the rock mass of FIG. 3, The figure (A) shows the positional relationship seen from the side of a crack and the explorer for improved treatment rock masses. Shows the positional relationship between the crack and the spacecraft for improved processing as seen from above. It is a flowchart of the processing method of the rock mass including the method of evaluating the effect of the improvement processing of the rock mass of FIG. It is explanatory drawing of the procedure which determines c and (phi) among the methods of evaluating the effect of the improvement process of the bedrock of FIG. It is explanatory drawing of the procedure which determines a deformation coefficient among the methods of evaluating the effect of the improvement process of the bedrock of FIG. Fig. 4 is a schematic diagram of a test conducted to confirm the effectiveness of the method for evaluating the effect of the improvement process of the rock mass in Fig. 3. Fig. (A) shows the outline of the experimental device, and Fig. (B) shows the natural vibration. (C) shows the relationship between the natural frequency and the thickness of the inclusion, respectively. It is explanatory drawing of the method of the improvement effect of the conventional bedrock.

FIGS. 1 to 8 show a method for evaluating the effect of the improvement processing of a rock having a crack according to the first embodiment of the present invention and the spacecraft for the improved processing rock.
As shown in FIG. 1, the improvement process of the rock mass means that the flow bed 100 </ b> B of the excavation part 104 provided in the rock mass 100 having the crack 102 is grounded by grouting (referring to the filling of cement milk by a press-fitting device). Point to. A boring hole 108 is formed in the flow board 100B, and the improved processing rock explorer 1 is inserted into the boring hole to evaluate the effect of the improving process. For the convenience of explanation, first, an improved processing bedrock explorer will be explained.

  As shown in FIG. 2, the improved exploration rock bed explorer 1 includes a main body 2, drooping means 24, and a striking mechanism 28.

The main body 2 includes a casing 4, a plunger member 14, a vibration sensor 18, and a crack position confirmation device 20.
The casing 4 has a first end wall 6 </ b> A and a second end wall 6 </ b> B that close both ends of the horizontal cylindrical tube wall 5, and forms a cavity 8 therein.
The cylindrical wall 5 may be a rectangular tube (square tube) shape or a cylindrical shape, but in the preferred illustrated example, the vertical width is shorter than the cylindrical axis direction.
An insertion hole 10 is formed in the first end wall 6A, and a pair of ventilation holes 12 are formed in both sides of the upper wall portion of the cylindrical wall 5 in the cylinder axial direction (both end portions in the illustrated example).
Further, a locking portion 7 for fastening a below-described hanging wire is formed at an appropriate position (both portions in the cylindrical axis direction in the illustrated example) of the upper wall portion of the cylindrical wall 5.

A pair of contact portions E ₁ and E ₂ are provided on both sides of the main body 2. One or both of the contact portions E ₁ and E ₂ are preferably provided so as to protrude outward from the main body 2. Moreover, it is desirable that the rigidity of each of the contact portions E ₁ and E ₂ is greater than the rigidity of the rock mass. In the preferred illustrated example, the vertical widths of the contact portions E ₁ and E ₂ are set to be equal to or smaller than the vertical width of the main body 2.
In the present embodiment, the first contact portion E ₁ is provided as the plunger member 14, and the second contact portion E _{2 includes the} vibration sensor 18.
However, as shown in FIG. 4, a pair of contact portions E ₁ and E ₂ that also serve as support legs protruding from the main body 2 are provided separately from the vibration sensor, and these support legs are in contact with the boring holes 108 to support the main body 2. You may form so that it may do. Further, the contact portion may be provided separately from the support means of the main body.

The plunger member 14 is formed by attaching enlarged diameter portions 16 </ b> A and 16 </ b> B to both ends of the shaft turning arm portion 15. The plunger member 14 also serves as the first contact portion E _1, and is formed as a member of the easy rigid rod to transmit vibrations.
The shaft turning arm portion 15 is inserted into the insertion hole 10 in an airtight and slidable manner.
The first enlarged-diameter portion 16 </ b> A is a plate portion for contacting the hole surface of the boring hole 108, and is attached to the distal end side of the shaft turning arm portion 15.
The second enlarged diameter portion 16 </ b> B is a partition wall that divides the cavity 8 in the main body 2 into two parts (first space 8 a and second space 8 b), and is attached to the distal end side of the shaft rotating arm portion 15. At the same time, it is slidably and airtightly contacted to the inner surface of the cylindrical wall 5.
The plunger member 14 is
The plunger member 14 advances outward by exhausting air from the first space 8a and supplying air to the second space 8b.
The plunger member 14 is configured to retract inward by supplying air to the first space 8a and exhausting air from the second space 8b.

The vibration sensor 18 is fixed to the second end wall 6B of the main body 2. Vibration sensor 18 of this embodiment is built as previously described second contact portion E _2, the second contact portion E ₂ is formed as easily rigid box body to transmit vibrations. The vibration sensor 18 is connected to a signal detection device 34 placed at an appropriate position (on the rock in the illustrated example) by wire or wireless.

In the present invention, a portion extending from the first contact portion E1 to the second contact portion E2 in the configuration of the main body 2 is used as the rigid expansion / contraction mechanism S. Vibration sensor 18 described above may be provided in place of the rigid telescopic mechanism S, may not be shared with the second contact portion E ₂ as in the illustrated example.
It is preferable that the rigid expansion / contraction mechanism S has such a rigidity that it can detect vibrations of the rock portions on both sides of the crack 102 by hitting the hitting mechanism 28 described later. In particular, the first contact portion E ₁ and the second contact portion E ₂ of the foregoing it is preferable to have a more rigid rock.

The crack position confirmation device 20 is preferably for confirming the position of the crack 102 with respect to the main body 2, and is attached to an appropriate position on the outer surface of the main body 2 (in the illustrated example, the lower surface of the lower wall portion of the cylindrical wall 5). .
The crack position confirmation device 20 can be formed by optical means such as a borehole camera. An optical means such as a borehole camera can take an image of 360 ° inside the hole, thereby accurately grasping the crack position. An image taken by optical means is displayed in a developed view or the like by an image device (not shown) so that the height of the crack according to the direction in the hole can be confirmed.

The drooping means 24 is a means for dripping the main body 2 into the boring hole 108 and can be formed of a string-like member such as a wire 25, for example. A wire or the like is suspended from an appropriate holder 30 installed on the ground, and a lower end of the wire or the like is fastened to a locking portion of the main body 2.
In a preferred illustrated example, at least two string-like members are locked on both sides of the cylinder wall 5 of the main body 2 in the cylinder axis direction. In this example, the orientation of the main body 2 can be changed by operating two string-like members.

The striking mechanism 28 is attached to a proper position of the main body 2 and is formed so that the hole surface of the boring hole 108 can be hit. The striking mechanism 28 of the present embodiment includes a shaft portion 28a provided on the lower wall portion of the cylindrical wall 5 of the main body 2, a rotating arm portion 28b connected to the shaft portion 28a, and a distal end portion of the rotating arm portion 28b. It is formed by an attached weight portion 28c and a string 28d connected to the tip of the rotating arm portion 28b.
And it is comprised so that a striking operation can be performed by pulling up and releasing the string 28d.
In the present embodiment, the striking mechanism 28 is configured to strike against the direction connecting the two contact portions of the main body (in the illustrated example, the hole surface portion on the second contact portion side). However, the structure can be changed as appropriate.
Further, in the illustrated example, the hitting position by the hitting mechanism 28 is located below the installation position of the borehole camera.

Hereinafter, a method for evaluating the effect of the improvement treatment of the rock having a crack according to the present invention will be described.
In addition, as shown in the flowchart of FIG. 5, it is desirable that the evaluation method for the improvement process of the present invention is performed in a series of processes including additional measures when the evaluation is insufficient. Here, for convenience of explanation, only the method of the present invention will be described first.

(1) Drilling a boring hole After the flow bed 100B adjacent to the excavation part 104 of the rock 100 is improved by a grouting method to form a retaining structure, a boring hole 108 is drilled in the structure (FIG. 3A )reference).
The bore diameter of the bore hole 108 is usually about 46 mm, and in FIG. 1 and FIG.
Although it is desirable that the length of the boring hole 108 is approximately equal to the depth of the excavating portion 104, the length is not limited thereto. However, in order to use Equation 1 described later as an evaluation method, it is necessary to leave about 1 m from the ground surface. This is because L shown in Formula 3 is about 1 m.
In order to evaluate the effect of the improvement of the entire retaining structure, the boreholes 108 are desirably provided at intervals of about 3 m in the same manner as the boreholes for improving the rock mass.
(2) Introduction and preparation of improved processing rock explorer 1 in the borehole As a preparation for the introduction of improved processed rock explorer 1, improved processed rock explorer 1 is located near the hole of borehole 108. A holder 30, an air supply device 32, and a signal detection device 34 that can be suspended are prepared (see FIG. 3B).
In addition, these apparatuses are only drawn schematically in the drawings, and these apparatuses should not be interpreted in a limited manner from the drawings. Any structure is sufficient as long as each function can be performed. It is desirable that the signal detection device 34 also serves as a display device that displays an image from the borehole camera.
Then, the vent hole 12 and the air supply device 32 of the improved processing rock explorer 1 are connected by the vent pipe 26, the locking portion 7 of the main body 2 and the holding tool 30 are connected by the wire 25, and the striking mechanism 28 is further connected. The upper end of the string 28d is held at a suitable position on the ground so as not to fall into the boring hole 108, so that the improved exploration rock rock explorer 1 can be introduced into the boring hole 108.
In addition, since the depth of the crack mark 102a can be evaluated with high accuracy by a borehole camera which is a conventional technique, the depth distribution of the crack mark 102a can be grasped before measurement by using the borehole camera alone.
In addition, the slope direction of the crack in the rock should have been investigated at the stage of designing the retaining structure, so check the slope direction in advance.
Then, the improved exploration rock bed explorer 1 is suspended in the borehole 108 so that the orientation of the main body 2 (direction connecting the two contact portions) substantially coincides with the inclination direction of the crack (see FIG. 3B). .
(3) Adjusting and fixing the position of the improved processing rock explorer 1 After suspending the improved processing rock explorer 1 into the borehole 108, the crack position confirmation device 20 observes the hole surface of the borehole 108. Then, the spacecraft 1 for improved processing is lowered.
When the crack mark 102a is found, the position of the improved processing rock explorer 1 is adjusted so that the main body 2 can come into contact with the rock parts on both the upper and lower sides of the crack mark 102a. For example in the case of the illustrated example, inclined in the inclination direction lower side of the crack first contact portion E ₁ is located above the crack trail 102a, and the second contact portion E on the lower side of the crack trail 102a in the inclined direction upward _What is necessary is just to adjust height so that ₂ may be located.
Then, at this height, the air supply device 32 is operated so as to exhaust air from the first space 8a and supply air to the second space 8b, so that the first contact portion E1 is pushed outward and the first contact is made. part E ₁ and the second contact portion E ₂ is pressed against the two places on both sides of the hole surface of the borehole 108, to fix the posture of the main body 2 (see Figure 3 (c)).
(4) Blowing the borehole 108 to the hole surface After fixing the rock exploration machine 1 in the borehole 108, the string 28d is operated and the rocking mechanism 28 is used to strike the rock portion below the crack mark 102a. To do. At this time, the test is performed in a state where an air pressure of about 5 atm is applied to the second space 8b. As a result of actual measurement in this state, it has been experimentally confirmed that undesirable vibrations in the cylinder and the piston do not occur.
This striking causes the rock portion below the crack mark 102a to vibrate, and the vibration is transmitted to the upper vibration portion of the crack mark 102a through the crack.
Vibration sensor vibration of the lower rock portion of the crack trail 102a is transmitted to the vibration sensor 18 in the second contact portion E _2, while the vibration of the upper rock portion of the crack trail 102a via the first contact portion E ₁ It is transmitted to 18. The vibration detected by the vibration sensor 18 is sent to the signal detection device 34 as a signal.
When a striking operation is performed with one crack mark 102a, the air supply device 32 is operated to retract the first contact portion E1 inward to release the fixed state to the borehole 108, and further exploration for improved processing rock mass The machine 1 is lowered and the same operation is repeated. When the improved processing rock explorer 1 reaches the lower end of the borehole 108, the improved processed rock explorer 1 is lifted to the ground.
(5) Evaluation of the signal detected by the vibration sensor 18 When the grout is properly filled in the crack, the vibration patterns of the rock portions on both the upper and lower sides of the crack mark 102a are substantially the same, but the grout is appropriate in the crack. If it is not filled, the vibration pattern shifts and the vibration frequency f detected by the vibration sensor 18 changes.
The relationship between the vibration frequency and the deformation coefficient E is given by the following equation.
[Formula 1] E = a × f ² (where a is a constant determined from the test results)
The process of deriving this equation is described in Example 1.
FIG. 7 shows the result of the deformation coefficient E calculated from the detected frequency at the plurality of crack marks 102a. The estimated value Emeans of the deformation coefficient when the improved crack is healthy at a certain depth in the borehole 108 is indicated by a solid line, and the measurement value of the deformation coefficient when the improved crack is still unhealthy. Ef is indicated by a point on the dotted line. The deformation coefficient Ef of the unhealthy location is lower than Emeans.
Therefore, it can be seen at a glance that a further improvement treatment is necessary for the crack.
When obtaining the shear strength τ ″ of the crack from the deformation coefficient Ef of the crack, the following equation is used.
[Formula 2] τ ″ = [(Ef) / (Emeans)] × τ ′

The operation of the method for evaluating the effect of the improvement treatment of a rock having cracks according to the present invention will be described.
(1) First, before grouting,
If the crack near the measurement point is in close contact, or if no crack exists at the measurement point, it can be measured that the natural frequency is large and the deformation coefficient is large.
・ When a crack is open or a soft material such as clay is interposed, it can be measured that the natural frequency is small and the deformation coefficient is small.
Such an evaluation becomes possible.
(2) After grouting,
・ When the crack is filled by grouting, it can be measured that the natural frequency is large and the deformation coefficient is large.
・ If the crack is not fully filled after filling the open crack in the rock mass with grouting, it can be measured that the natural frequency near the measurement point is small and the deformation coefficient is small.
-After the cement crack is filled in the open crack in the rock mass by grouting, the inclusion 103 having a smaller deformation coefficient than the soft clay-like rock mass remains in a part of the crack (see Fig. 1). It can be measured that the natural frequency near the measurement point is small and the deformation coefficient is small.
It is possible to determine the effect of grouting.
The inclusion can be measured even if it is considerably thin. In the experiment, a thickness of 1 mm could be measured.

Hereinafter, experiments and embodiments supporting the present invention will be described as examples.
Example 1 Method for Evaluating Deformation Coefficient E of Crack Part In the present invention, as shown in FIG. 1, a test apparatus was installed on the upper and lower rocks with the crack part interposed therebetween, and the inside of the hole was hit. By measuring the natural frequency, the deformation coefficient of the crack near the test device is evaluated.
The natural frequency f (Hz) at the time of hitting an object can be obtained by the following equation as shown in the previous application.
[Formula 3]
Here, E: Deformation coefficient, g: Gravitational acceleration, I: Cross-sectional moment, A: Cross-sectional area, L: Vibration length, ρ: Density It is difficult to accurately define each constant by the above equation. When hitting the bedrock in the borehole, you will hit a part of the bedrock that is a continuum with a large mass. In this case, constants other than E can be considered to be approximately constant depending on the location of the impact. That is, the above-described formula 1 (E = a × f ² ) is established between the natural frequency f and the deformation coefficient E.
As is clear from Equation 1, the natural frequency increases when the deformation coefficient is large and the deformation is difficult.

In order to confirm this relationship, a hitting experiment was conducted using the rock model shown in FIG.
The experiment uses a 9cm x 9cm x 18cm granite block shown in the upper figure of Fig. 8, and the thickness of a rubber sheet sandwiched between the blocks (assuming that there is a low-strength filler such as viscous soil in the crack) Was performed as a parameter.
The result of evaluating the natural frequency is shown in FIG. It is confirmed that the natural frequency is lower at 1 mm and 4 mm (assuming that there is a low-strength filler in the opened crack) compared to the rubber sheet thickness of 0 mm (assuming that the crack is in close contact). did it.
It was also found that the natural frequency did not change even when the rubber sheet thickness changed. FIG. 8C shows the result of an experiment in which an air sheet (so-called bubble cushioning material) used as a packing material instead of a rubber sheet is sandwiched with a thickness of 4 mm.
Since the deformation coefficient of the air sheet is clearly lower than that of rubber, the measurement result shows that the natural frequency of the air sheet is the smallest. In the test shown in FIG. 8A, the tendency of the measured value of the natural frequency measured when there is a weak surface simulating a crack was obtained.
In other words, the measured natural frequency is considered to be strongly influenced by boundary conditions such as the effect of fixation due to its own weight when the test model is placed on the floor. It is impossible to directly determine the deformation coefficient of the air sheet.
On the other hand, when the measurement as shown in FIG. 9A is performed in the borehole, the boundary surface is the ground surface = the rock surface. Therefore, there is a possibility that the accuracy of measurement is inferior due to the influence of the boundary condition in the portion where the earth covering is small and close to the ground surface. However, if the impact energy is small as in the present invention, if it is about 1 m away from the ground surface. Since the influence of the boundary condition is considered negligible, it is considered that no problem occurs in the evaluation of the deformation coefficient of the crack.
From these things, the deformation coefficient of the crack part which could not be measured accurately by the prior art can be evaluated by the present invention.

The deformation coefficient of the CL grade rock mass to be improved by grouting is 6000 kg / cm ² or less, and the deformation coefficient of the CM grade rock mass that is the improvement rock grade after grouting is about 10,000 kg / cm ² (3000 to 20000 kg / cm ² ). ² ).
On the other hand, the deformation coefficient of the grouting material (cement milk with a uniaxial compressive strength of about 100 kg / cm ² at 28 days strength) is considered to be about uniaxial compressive strength × 150 times as in the cement-improved soil.
In this case, the modulus of deformation of the grouting material ^{100kg / cm 2 × 150 = 15000kg} / cm 2 becomes larger than the modulus of deformation of the CL class rock, a value comparable to the CM-grade rock improvement goals. Therefore, deformation coefficient of the rock after grouting is believed to rise to about 10000 kg / cm ² from 6000 kg / cm ² or less. The basic idea is to ensure that the grouting is properly construction the deformation coefficients after construction is considered may be confirmed by measurement according to the present invention that is about 10000 kg / cm ^2.

[Example 2] (Evaluation method of shear strength τ of rock mass)
Next, a method for evaluating the shear strength τ of the rock before grouting is described. In the prior art, the horizontal loading test in the hole was conducted at the depth of Z from the ground surface in the rock mass with unit volume weight γ, and the yield pressure (yield after the load strength increased linearly with the increase in hole diameter in the same test) Pressure). In this case, in the prior art, the minimum principal stress is the earth covering pressure γZ, and the maximum principal stress is the yield pressure. Using these two points, a mall circle is drawn as shown in FIG. This work is carried out with experimental results at various depths and various boreholes, and a group of mall circles as shown in the schematic diagram of Fig. 6 is drawn, and the envelopes that touch the average are set by the method of least squares, etc. To do. The section of the envelope is the average adhesion c of the rock, and the gradient φ of the envelope is the average internal friction angle.
If the angle formed by the crack with respect to the horizontal plane is α, the component perpendicular to the crack of the earth pressure (vertical stress) is γZ × cosα. Therefore, the horizontal axis in FIG. 6 represents the fracture envelope corresponding to γZ × cosα. The value is the shear strength τ ′ of the crack. For the rock after grouting, c and φ can be evaluated by the same procedure as described above.
In the present invention, it is the same until the average c and φ of the rock mass are obtained, but the rock mass and crack E obtained by the test apparatus shown in FIG. 3 are arranged as shown in FIG. The relationship between the average E and the earth covering pressure σ is obtained by a linear equation by the least square method or the like. FIG. 7 is a schematic diagram of the relationship between the deformation coefficient of the rock before grouting and the earth pressure. Before the grouting, a crack having an inclusion such as soft clay has a small deformation coefficient as shown in the lower part of FIG. Since the deformation coefficient and the shear strength are considered to be approximately proportional, the shear strength τ ″ of the cracked portion is evaluated as shown in Equation 2 from τ ′ obtained in FIG.
τ ″ = ((E of crack part) / (E _MEAN )) × τ ′
The shear strength can be similarly evaluated for the rock after grouting. By doing so, it becomes possible to accurately evaluate the shear strength of the cracked part, and it is possible to identify in advance the place where the effect of the rock mass improvement treatment by grouting is insufficient, so that the properties of the bedrock rock mass can be grasped. it can. For this reason, when constructing a retaining structure by grouting, insert a reinforcing bar into a boring hole having insufficient locations to increase shear strength, narrow the boring hole placement interval, and grouting. It is possible to take measures such as grouting by increasing the number of placements or grouting by widening the placement range of the boring holes, which greatly contributes to construction management.

[Example 3] (Use status of spacecraft for improved processing rock)
The present invention relates to a construction management method in the case where a flow bed rock is improved by grouting to form a retaining structure. The position of the crack and the running / tilting of the crack can be accurately evaluated by the conventional borehole camera.
The flow bed rock generally means that the crack is inclined by about 30 ° to 60 ° from the horizontal plane.
A typical diameter of a boring hole used for grouting is 46 mm. In this case, the difference in the height of the crack surface at the borehole (difference between the highest position and the lowest position) is 46 × tan 30 ° = 26.6 mm when the inclination is 30 °, and 46 × tan 60 ° when the inclination is 60 °. 79.7 mm.
Ideally, the spacecraft of this application shown in FIG. 2 should be installed in the direction of inclination of the flow board, that is, in the direction where the difference in height of cracks in the borehole is the largest. However, as shown in FIG. 4B, even if there is an error of ± 45 °, the difference in height of the crack is 26.6 / 2 = 13.3 mm when the inclination is 30 °. Absent.
Therefore, an error of ± 45 ° is allowed in the installation direction of the test apparatus in the horizontal plane. In the above-mentioned prior application, in order to accurately measure the diameter of a concrete pile, a measuring instrument is lowered into the borehole with a double tube rod, and the measurement is performed by fixing the device in a predetermined direction in a horizontal plane. Yes. On the other hand, in the present invention, as shown in FIG. 2, the test apparatus is suspended by a wire and lowered into the boring hole, and measurement is performed by fixing the test apparatus with air pressure. As a result, the time required to add the rod can be greatly reduced, and measurement with high work efficiency can be performed.

[Example 4] (Use status of spacecraft for improved processing rock)
FIG. 5 shows a procedure for processing the improved ground including the evaluation method of the present invention.
(1) Drill a borehole in the rock before grouting, insert a borehole camera into the borehole, and measure the depth of the crack. Further, the spacecraft 1 according to the present invention is installed at a plurality of points in the depth direction and hit with an iron ball, and the deformation coefficient is evaluated as schematically shown in FIG. At this time, measurement by the probe 1 is performed at the crack portion specified by the borehole camera. In addition, the in-hole loading test, which is the existing technology shown in FIG. 9, is performed at a plurality of depths, and the average c and φ of the rock mass before improvement are drawn as shown in FIG.
(2) Improve the rock mass by pressing cement milk into the borehole by grouting and filling the crack with cement milk.
(3) After improving the bedrock, the borehole is filled with cement milk, so drill the borehole again.
(4) Then, the depth of the crack in the borehole is measured again with the borehole camera.
(5) Then, an adhesive force c and an envelope gradient φ are obtained by a conventional in-hole loading test in the borehole, and the deformation coefficient E is measured by the method of the present invention.
(6) The shear strength τ ″ of the crack portion is obtained using Equation 2 above.
(7) The stability calculation of the slope (cracked surface) is performed to examine whether slip failure can occur.
(8) When it is determined that slip failure does not occur, it can be determined that the effect of rock mass improvement by grouting is obtained.
(9) On the other hand, when it is determined that slip failure occurs, it can be determined that the improvement effect by grouting is not sufficiently obtained. In this case, the adoption of a method of increasing the shear strength by inserting a reinforcing bar into the borehole will be considered.
By carrying out the above procedure before the main construction of grouting, it is possible to confirm in advance the improvement effect of the rock mass by grouting. If an improvement effect is obtained, this construction can be carried out as scheduled. When the improvement effect is insufficient, the main construction can be performed after taking countermeasures such as carrying out the main construction together with an auxiliary method such as inserting a reinforcing bar.

  The description of the above embodiment is one of the technical aspects of the present invention, and unless otherwise contradicted by the technical significance of the present invention, matters not described in the column of this embodiment are also the invention specific matters of the present invention. Should be interpreted as included.

DESCRIPTION OF SYMBOLS 1 ... Explorer for improved processing bedrock 2 ... Main body 4 ... Casing 5 ... Cylindrical wall 6A ... 1st end wall 6B ... 2nd end wall 7 ... Locking part 8 ... Cavity 8a ... 1st space 8b ... 2nd space 10 ... Insertion hole 12 ... Vent hole 14 ... Plunger member 15 ... Shaft rotating arm part 16A, 16B ... Diameter enlarged part 18 ... Vibration sensor 20 ... Crack position confirmation device (camera) 24 ... Dripping means 25 ... Wire 26 ... Vent pipe 28 ... Blow mechanism 28a ... Shaft 28b ... Rotating arm 28c ... Weight 28d ... Suspension 30 ... Holder 32 ... Air supply device 34 ... Signal detector 100 ... Rock 102 ... Crack 102a ... Crack mark 103 ... Inclusion 104 ... Excavation part 106 ...
108 ... borehole E 1 _... first contact portion E 2 _... second contact portion PR ... rubber sheet S ... rigid telescopic mechanism T ... direction adjusting unit V ... space W1, W2 ... wall Z ... bottom plate portion

Claims (4)

A method for evaluating the effect of improvement treatment of a rock mass having a crack by a change in a deformation coefficient near the crack,
A step of forming a borehole in the rock so as to cut through the crack marks by the improvement process;
Throwing a probe with contact portions at both ends of the main body into the boring;
Contacting one contact portion with a rock portion above one crack mark, and contacting the other contact portion with a rock portion under one crack mark,
Striking the hole surface of the boring hole above or below the crack mark in a state of contacting both rock portions through the contact portion;
Detecting the vibration of the spacecraft due to the hitting with a vibration sensor provided in a proper position of the spacecraft,
Comprising
The rigidity of at least the contact portion of the probe is larger than the rigidity of the rock mass,
It is characterized by judging the appropriateness of the effect of the improvement process by comparing the signal observed by the observation device with the standard signal when the improvement process is appropriate.
A method to evaluate the effect of improvement treatment of rock mass with cracks. Cracks in the bedrock before improvement are inclined,
One contact part that contacts the upper side of the crack mark is positioned on the lower side of the crack inclination direction, and the other contact part that contacts the lower side of the crack mark is positioned on the upper side of the crack inclination direction. The method for evaluating the effect of the improvement processing of a rock having a crack according to claim 1, wherein the direction of the spacecraft is adjusted. A body having contact portions on both sides;
Drooping means for dripping this body into the borehole;
A striking mechanism connected to the main body for striking the hole surface of the boring hole;
With
It has a rigid expansion and contraction mechanism that can expand and contract from one contact part of the main body to the other contact part and exhibits rigidity at the time of hitting by at least the hitting mechanism,
An exploration machine for improved processing rocks, characterized in that a vibration sensor is provided in a part of this rigid expansion / contraction mechanism. The exploration machine for improved processing rock mass according to claim 3, wherein means for adjusting the orientation of the main body with respect to the circumferential direction of the boring hole is provided.