JP2003213662A - Grout injection method and confirmation method of bag expansion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grout injection method capable of easily judging that a bag is sufficiently expanded in a drilled hole to the degree that a desired function can be exhibited as a bag buried matter and properly judging the stop timing of grout injection. <P>SOLUTION: In this grout injection method to the bag 1a when inserting the bag 1a into the drilled hole 3 of ground E and injecting grout 1b to the bag 1a to form a buried matter 1, the stop timing of grout injection is judged by managing the change in injection pressure in the injection of the grout 1b to the bag 1a. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injecting grout into a bag body inserted into a hole drilled in the ground to use it as an anchor, compaction of the ground, and the like, and a diameter expansion of the bag body. It is related to the confirmation method.

[0002]

2. Description of the Related Art An embedding material for inserting a bag into a hole drilled in the ground, injecting grout into the bag, and compacting the anchor or the ground (hereinafter referred to as "bag embedding"). Is often used as. In such a method of injecting grout into the bag, the bag is sufficiently expanded in the drilling hole at the time when a predetermined amount of grout that has been determined in consideration of the bag volume is injected. It is common to stop the grout injection, presuming that it is present.

However, depending on various conditions such as the type of bag, the state of grout to be injected, the state of the ground in which the buried object of the bag is buried, the bag is sufficiently expanded in the drilled hole to achieve the desired pull-out resistance. The amount of grout that can exert functions such as strength changes. Further, in order to sufficiently expand the diameter of the bag body within the drilled hole, if too much grout is injected, the bag body may be broken. On the other hand, if the bag body is warned too much and the grout is not sufficiently injected, the bag body will not be sufficiently expanded in diameter and the desired function as the bag body embedded object will not be exhibited. Therefore, it is the actual situation that it is necessary to rely on a skilled construction manager to determine the timing of stopping the grout injection.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides that the bag body is sufficiently expanded in the drilling hole to the extent that the bag body can exhibit a desired function. It is an object of the present invention to provide a grout injection method and a bag body diameter expansion confirmation method that can be easily confirmed and can appropriately determine the stop timing of grout injection.

[0005]

According to a first aspect of the present invention, there is provided a grout injection method, wherein a bag is inserted into a hole drilled in the ground and the bag is injected with the grout. A method of injecting grout into the bag when
It is characterized in that the timing of stopping the grout injection is determined by managing the change in the injection pressure when the grout is injected into the bag.

According to this structure, the injection state of grout into the bag can be grasped by managing the grout injection pressure into the bag. That is, when the grout is injected into the bag, the bag is filled with the grout, the bag is filled with the grout and then the diameter is expanded while the ground is being expanded, and the bag is sufficiently expanded. The fiber undergoes various states such as the state where the fiber is under tension, but these states can be grasped by managing the change in the injection pressure. Thereby, it is possible to easily confirm that the bag body is sufficiently expanded in the drilling hole to the extent that the bag buried object can exhibit a desired function, and it is possible to appropriately determine the grout injection stop timing. .

According to a second aspect of the present invention, in the grout injection method according to the first aspect, the critical pressure at which the bag breaks is reached after the change rate of the injection pressure once decreases and then increases again. It is characterized by stopping the grout injection before reaching.

According to this structure, first, it is possible to grasp the timing at which the fibers of the bag body start to be tensioned after the bag body expands the ground by expanding the ground sufficiently by the grout filling the bag body. That is, when the rate of change of the grout injection pressure once decreases, it is possible to grasp the timing when the grout is filled in the bag body, and when it starts to increase again later, the bag body pushes the ground and expands sufficiently. It is possible to grasp that the fibers of the bag have begun to be tense by expanding the diameter. Then, by stopping the injection of grout before reaching the critical pressure at which the bag breaks, it is possible to inject the grout until the function as a bag buried object can be fully exerted without damaging the bag. You will be able to

According to a third aspect of the present invention, in the grout injection method according to the first or second aspect, the change in the injection pressure is an injection pressure change managed with respect to the change in the grout injection amount.

According to this structure, it is possible to more accurately grasp the state of grout injection in the bag body. That is, since the change in the grout injection pressure is largely influenced by the volume of the bag, the change in the injection pressure with respect to the change in the grout injection amount is managed to more clearly understand the change in the injection pressure. be able to.

According to a fourth aspect of the present invention, in the grout injection method according to any one of the first to third aspects, the injection pressure change is managed while being displayed in real time.

According to this structure, when the injection stop timing judged from the change in the grout injection pressure comes, the injection stop can be immediately dealt with, and the injection can be stopped at an appropriate timing.

According to a fifth aspect of the present invention, in the grout injection method according to any one of the first to fourth aspects, a time point at which the rate of change of the injection pressure once decreases and then increases again is detected using an automatic determination means. In addition, it is characterized by automatically stopping after this detection.

According to this structure, it is possible to prevent the human error from occurring in the judgment of the grout injection stop timing and the stop operation, and it is possible to surely perform the construction management.

According to a sixth aspect of the present invention, in the grout injection method according to any one of the first to fifth aspects, the upper limit of the injection pressure is set, and when the upper limit of the injection pressure is reached, the injection of grout is stopped. It is characterized by doing.

According to this structure, even when the surrounding ground is particularly hard, or conversely, when the ground is extremely soft, it is difficult for the change in the grout injection pressure to appear clearly,
The grout injection can be stopped without causing damage to the bag.

According to a seventh aspect of the present invention, in the grout injection method according to any one of the first to sixth aspects, an upper limit value of the grout injection amount is set, and when the injection amount is reached, the grout injection is stopped. Is characterized by.

According to this structure, even if the bag body is damaged without the change in the grout injection pressure being apparent, the outflow of the grout to the surrounding ground can be suppressed. Therefore, an efficient grout injection method can be provided in terms of environment and economy.

According to the method for confirming the expansion of the bag body according to claim 8, when the bag body is inserted into a hole drilled in the ground, and the grout is injected into the bag body to be an embedded object, the bag body is desired. A method for confirming that the bag has been expanded by a certain amount, which is a rate of change in the injection pressure when the grout is injected into the bag after the completion of the grout injection, and then once decreases and then increases again. It is characterized in that it is confirmed that the bag body is expanded by a desired amount by confirming that the time when the bag was present was present.

According to this construction, after the bag body has sufficiently expanded its diameter while expanding the ground by the grout filled in the bag body, the grout injection is stopped after the fiber of the bag body starts to be tensioned, It can be confirmed after grout injection. That is, it can be confirmed after the completion of construction that the bag body is sufficiently expanded in the drilling hole to the extent that the bag body embedded article can exhibit a desired function.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 shows an example of the bag-embedded object used in the present embodiment. 2A shows a state in which the bag body embedded object 1 of FIG. 2A is embedded in the ground E as a bag body anchor 1 which is a component of a foundation for supporting a structure or the like.
The bag body embedded object 2 of (b) is a schematic diagram showing a state of being buried in the ground E for compaction of the ground.

In FIG. 2 (a), the bag anchor 1 is obtained by injecting the grout 1b from the injection metal fitting 1c into the bag 1a inserted into the hole 3 formed in the ground to solidify the bag. It is formed. The bag body 1 a is formed as a tubular woven fabric and has a diameter larger than the inner diameter of the drilled hole 3. The bag body 1a made of this tubular woven fabric can be expanded in diameter by pouring the grout 1b so that the volume thereof is almost doubled. As shown in FIG. 2A, the bag body anchor 1 functions as an anchor by expanding the bag body 1 to have a diameter larger than the drilled diameter. Note that FIG. 2 (a) shows the one provided with the reinforcing bar injection pipe 1d. The reinforcing bar injection pipe 1d serves as a strength member and also serves as a supply path for injecting grout into the bag 1a through the inside of the injection pipe.

The bag body embedded object 2 shown in FIG. 2 (b) is also provided with a bag body 2a made of a tubular woven fabric, like the bag body anchor 1, and the grout 2b is inserted in the bag hole 2a. It is formed by injecting and solidifying. This bag body buried object 2 is
Unlike the bag anchor 1, it is used for compaction of the ground E, and thus is formed in a shape that matches the improvement range of the ground E. Inside the bag body 2a, a rebar injection pipe 2d communicating with the injection fitting 2c is provided. This rebar injection pipe 2
d has a plurality of holes 2e, and the grout 2b
Is injected into the bag body 2a through the hole 2e through the rebar injection pipe 2d. Bag 2 with grout injected
The diameter a is larger than the inner diameter of the drilled hole 3, and the ground E is compacted.

The present invention provides a grout injection method which is mainly used when forming a bag-burying object as described above.

First, construction management means for carrying out the grout injection method according to this embodiment will be described. Figure 1
Shows an outline of the construction management means 10, the bag anchor 1, the ground E and the like. A plurality of drilled holes 3 are formed in the ground E, and the bag body 1 a is formed in each drilled hole 3.
Are inserted, and grout is injected and solidified, whereby the bag anchor 1 is formed. The grout to be injected into the bag 1a is supplied from the mixing pump 4. The mixing pump 4 includes a mixer 4a and a grout injection pump 4b.
An injection hose 5 is connected to b, and the tip of the injection hose 5 is connected to the above-described rebar injection pipe 1d (not shown). The infusion pump 4b is connected so as to be able to receive a signal from the controller 8 of the construction management means 10 which will be described later, and can stop its operation based on a command from the controller 8.

The construction management means 10 is a sensor unit 6
And an amplifier 7 and a controller 8. First, the sensor unit 6 is provided in the middle of the injection hose 5 and includes a pressure gauge and a flow meter (not shown) for measuring the grout injection pressure and the injection amount, respectively. The sensor unit 6 is connected to an amplifier 7 that converts an analog signal from the pressure gauge and the flow meter into a digital signal, and the amplifier 7 is further connected to a controller 8. The controller 8 is stored in advance in the storage unit, a storage unit that stores and stores the measurement results of the grout injection pressure and the injection amount transmitted from the amplifier 7, a display unit that displays the measurement results as a graph on the screen, and a storage unit in advance. The measurement result is processed by the automatic judgment means consisting of a program to judge the injection stop timing,
And a processing unit that gives an operation stop command to the grout injection pump 4b of the mixing pump 4.

In the grout injection method according to this embodiment,
The construction management means 10 described above is used to manage the change in the injection pressure when the grout is injected into the bag 1a to determine the grout injection stop timing. Hereinafter, the grout injection method according to the present embodiment will be described.

FIG. 3 shows the procedure for constructing the bag anchor 1, and FIG. 4 shows an example in which the change in the grout injection pressure after the start of injection is plotted against the change in the grout injection amount. The graph shown in FIG. 4 is obtained by displaying the injection pressure and injection amount measurement results received by the controller 8 in the construction management means 10 on the screen in real time, for example. First, in FIG. 3, a hole 3 having a diameter smaller than that of the bag 1a is formed in the ground E (step I). And
A bag body 1a in which a rebar injection pipe 1d is inserted into the drilled hole 3
Is inserted (step II). In this state, the injection hose 5 is attached to one end of the reinforcing bar injection pipe 1d exposed from the drilled hole 3. As described above, the sensor unit 6 of the construction management means 10 and the mixing pump 4 are connected to the injection hose 5 (see FIG. 1).

From this state, the injection pump 4b of the mixing pump 4 is activated to start the injection of the grout 1b into the bag 1a (step III). The grout 1b flows into the bag body 1a from the tip 1e of the reinforcing bar injection pipe 1d and is injected. When the bag 1a is filled with the grout 1b, the bag 1a
Is in a state of being in close contact with the hole wall 3a of the drilled hole 3 (step I
V). Furthermore, if you continue to inject grout 1b,
Moisture in the grout is partly pressurized and dehydrated from between the textures of the bag body 1a, and the internal pressure of the bag body 1a rises with the initial expansion of the bag body 1a.

At this time (steps III and IV), the change in the grout injection pressure with respect to the change in the grout injection amount changes as shown by the solid line (a) in FIG. That is, after the start of the injection, the injection amount increases with the lapse of time, but the injection pressure hardly increases and remains low (step III). However, when the bag 1a is filled with the grout 1b and the bag 1a comes into close contact with the hole wall 3a (step IV), the injection pressure passes through the inflection point A where the injection pressure suddenly rises. . After passing through the inflection point A, the injection pressure also increases as the internal pressure of the bag body 1a increases. In the construction management means 10, by displaying the graph as shown in FIG. 4 in real time, it is possible to confirm that the bag body 1a is in close contact with the hole wall 3a (passing the inflection point A). The construction manager can know at almost the same time.

Again, referring to FIG. 3, when the bag 1a is in close contact with the hole wall 3a and the pouring of the grout 1b is continued while increasing the internal pressure, the internal pressure is sufficient to spread the ground. When this internal pressure is reached, the bag body 1a expands as the grout 1b is injected, and the ground forming the hole wall 3a that is in close contact with the bag body 1a is expanded accordingly, and the drilled diameter gradually increases. The diameter is reduced (step V).

At this time, the graph shown by the solid line (a) in FIG. 4 shows that a gradual pressure rise occurs from the process (step IV) in which a sudden pressure rise occurs at the time when the internal pressure is reached to spread the ground. Inflection point B that changes to the existing process (process V)
Pass through. That is, by grasping the occurrence of the inflection point B from the graph that is displayed in real time, the construction manager can confirm that the injection state is such that the bag body 1a spreads the ground and expands the drilling diameter. You can know that you have transitioned. Further, after passing through the inflection point B, the gradual pressure increase continues, so that the construction manager can proceed with the work while confirming that the bag body 1a is steadily expanding the drilled hole 3. .

In the processing section of the controller 8,
The existence of the inflection point B is grasped by processing the measurement result (p) of the grout injection pressure and the measurement result (q) of the injection amount by the above-described automatic determination means as follows.

First, the change rate of the injection pressure (p ') and the change rate of the injection amount (q') are calculated according to the following equations and, respectively. p ′ = Δp / Δt q ′ = Δq / Δt Here, Δt is the calculation cycle unit time, and Δp and Δq are the change amounts of the injection pressure and the injection amount between Δt, respectively. The second-order differential equivalent value of the injection pressure (p) with respect to the injection amount (q), that is, the rate of change of the injection pressure change with respect to the injection amount (d ² p / dq ² ) is calculated according to the following equation. (D ² p / dq ² ) = {Δ (p ′ / q ′) / Δt} / q ′ where Δ (p ′ / q ′) is (p ′ / q ′) during the calculation cycle time Δt. The amount of change in value. Δ from the above formula
Second derivative equivalent value (d ² p / dq ² ) calculated every t hours
However, once it becomes a negative value, the processing unit of the controller 8 recognizes that it has passed the inflection point B. That is, it is understood that the rate of change of the injection pressure with respect to the injection amount has once decreased.

Since the grout injection pump 4b is constantly operated and the injection rate change rate (q ') does not take a negative value, the second derivative equivalent value (d ² p / dq ² )
Does not need to recognize the inflection point B when N becomes a negative value. For example, the previously calculated value of Δ (p ′ / q ′) (Δt
The inflection point B may be recognized by comparing the previous calculation value before time) with the current calculation value to make an increase / decrease decision.
Moreover, since the injection speed (the discharge amount per unit time) from the grout injection pump 4b is usually constant (that is,
q '= constant), Δp' / Δt becomes a negative value, or the inflection point B is recognized by comparing the previous calculated value and the current calculated value of Δp 'to increase or decrease. May be Note that Δp ′ is the amount of change in p ′ during Δt.

Referring again to FIGS. 3 and 4, after passing through the inflection point B and further continuing the gradual increase in the grout injection pressure, the bag body 1a is completely inflated by the injection of the grout 1b, The fibers of the bag body 1a start to be tense. Then, the bag body 1a is in a state of being sufficiently expanded in diameter within the drilled hole 3 (step VI). At this time, the graph indicated by the solid line (a) in FIG. 4 changes from a gradual pressure increase to a rapid pressure increase via the inflection point C. That is, when the fibers of the bag body 1a start to be tense, the inflection point C comes and the pressure rises sharply. When the inflection point C is generated, that is, when the rate of change of the injection pressure with respect to the injection amount once decreases (passes the inflection point B) and then starts to increase again, the bag body 1a is drilled. It becomes possible to judge that the diameter is sufficiently expanded within 3.

Whether the vehicle passes the inflection point C can be judged by the construction manager from the graph showing the relationship between the injection pressure and the injection amount displayed in real time on the controller 8 (see FIG. 4). It is also detected by the automatic determination means in the processing section as follows.

First, as described above, when the second-order differential equivalent value (d ² p / dq ² ) calculated for each Δt time by the equation once becomes a negative value, it passes through the inflection point B. Recognize what you have done. Then, the inflection point C is recognized when the (d ² p / dq ² ) value, which was a negative value, turns to a positive value again. The controller 8 recognizes the inflection point C as follows.
In the same way as when the inflection point B is recognized, Δ (p ′ /
q ') is compared with the previous calculated value and the current calculated value to make an increase / decrease judgment, or Δp' / Δt is a positive value, or the previous calculated value of Δp 'is compared with the current calculated value. It may be carried out by determining increase / decrease by

As described above, by detecting that the controller 8 has passed the inflection point C, the grout injection stop timing is determined, and a pump operation stop command is transmitted to the grout injection pump 4b. Thereby, the bag 1
The injection of grout 1b into a is stopped, and the diameter expansion of the bag body 1a is completed in the state shown in step VI of FIG. After that, the grout 1b injected into the bag body 1a is solidified, so that the bag body anchor 1 is formed. There is no particular problem with the setting of the grout injection stop timing after the point of passage of the inflection point C, but as shown by point VI on the solid line (a) of FIG. It is desirable to stop immediately (for reference, the transition of the graph when not stopped is also shown in FIG. 4). Then, it is necessary to set the injection stop timing at least before reaching the critical pressure at which the bag body 1a breaks.

The above is the description of the grout pouring method according to the present embodiment. However, when the surrounding ground is particularly hard or, conversely, it is very soft, the change in the grout pouring pressure does not appear clearly. Further, during the grout injection, the bag 1a may be damaged without a change in the injection pressure being apparent. For example, when the surrounding ground is very hard and cannot be spread by the bag 1a, the graph changes as shown by the dotted line (b) in FIG. When the ground is very soft or the bag 1a is damaged, the graph changes as shown by the dotted line (c) in FIG.

In consideration of these cases, it is desirable to preset the upper limit value of the grout injection pressure and the upper limit value of the injection amount. The upper limit of injection pressure is set, and when this value is reached, the grout injection is stopped even if it does not pass through the inflection point C, so that the graph changes as shown by the dotted line (b) in FIG. Even if it does, bag 1
It is possible to prevent the damage of a. In consideration of the safety factor of the bag body 1a, it is desirable to set the injection pressure upper limit value to about 70 to 80% of the breaking pressure when the grout is injected into the bag body 1a in the air instead of in the hole. . By the way, the breaking pressure of the bag 1a differs depending on the woven structure. In addition, in the grout injection method according to the present embodiment, since the grout injection is stopped by determining that the inflection point C has been passed, a bag body that withstands an excessively high breaking pressure is used as in the conventional case. You don't have to. Therefore, since the allowable breaking pressure can be determined and the bag body can be selected with reference to the pressure generated at the inflection point C,
It is also advantageous in terms of cost.

Similarly to the injection pressure upper limit value, the injection amount upper limit value is set, and when this value is reached, the grout injection is stopped even if the inflection point C is not passed, Even in the case where the graph changes as shown by the dotted line (c), it is possible to prevent the bag 1a from being damaged or to prevent the grout from flowing out to the surrounding ground even if it is damaged. it can. In addition, in general, even if dehydration from the bag 1a is taken into consideration, it is unlikely that the bag 1a will be filled with grout that is more than twice the volume of the bag 1a.
When the injection amount exceeds twice the volume of the bag 1a, the bag 1a
May be damaged. Therefore, if the injection is stopped when the volume exceeds twice, the outflow of grout to the surrounding ground is small and it is efficient in terms of environment and economy.

As described above, the grout injection can be automatically stopped by using the construction management means 10. However, even after the grout injection, the construction manager further determines the bag body as described below. Bag 1 according to the expansion confirmation method
It can be confirmed that the diameter a is expanded by a desired amount.

When the grout injection is stopped by the automatic injection stop, the information of the measurement result of the grout injection pressure and the injection amount transmitted from the amplifier 7 is stored and stored in the storage section of the controller 8. By displaying a graph showing the transition of the injection amount and the injection pressure shown in FIG. 4 on the screen of the measurement result on the display unit of the controller 8, the construction manager can inject the grout into the bag 1a. It can be confirmed that the rate of change of pressure had a time point (inflection point C) at which the pressure once decreased and then increased again. This makes it possible to confirm that the bag body 1a has a desired diameter after the grout injection.

Next, an example based on this embodiment will be described. The bag 1a has a diameter of 200 m
m with an effective length of 1500 mm, drilling diameter of 90
It formed in mm and implemented. Further, a diaphragm type pressure gauge was attached to the rebar injection pipe 1d of the bag body 1a, an analog signal from the pressure gauge was amplified by a dynamic strain measuring instrument, and collected by a data collecting system machine. The collected data is data observation software (example: WAVE S manufactured by KEYENCE CORPORATION)
HOT! 2000) and downloaded to a personal computer.
The data taken into the personal computer was displayed in real time on the screen from the start of the injection, with the injection amount on the horizontal axis and the injection pressure on the vertical axis. The bag 1a was injected with grout at an injection rate of 20 liters / minute.

FIG. 5 shows the same graph displayed on the screen in this embodiment. Upon visually observing the graph displayed in real time at the time of grout injection, it was confirmed that the inflection points A, B, and C occurred in order. In addition, inflection points A to C and steps are shown in FIG.
The symbols III to VI are attached to the corresponding portions.

Further, after the inflection point C was visually confirmed, it was also confirmed that the injection was automatically stopped by the construction management means 10. As shown in FIG. 5, the injection pressure when stopped was about 0.5 MPa, and the injection amount was about 55 liters. The construction management means 10 used in this example was provided with a buzzer that sounds at the same time when the injection is stopped, in order to notify the construction manager of the injection stop. Therefore, after visually confirming the passage of the inflection point C on the screen, the buzzer sounds,
The construction manager was able to quickly recognize that the grout injection had stopped automatically. In this embodiment, the pressure gauge is attached to the reinforcing bar injection pipe 1d, but the bag 1a is
It is preferable to attach it at a position close to. This is because if the pressure gauge attachment position (pressure measurement position) is separated from the bag body 1a, an error due to pressure loss and a time lag may increase. When the bag body 1a was dug up for confirmation after the grout was cured, the bag body 1a was filled with the cured grout, and the bag body 1a was in close contact with the hole wall 3a of the drilled hole 3 and was sufficiently expanded in diameter. It was in a state of being. The bag 1a was not damaged.

As another embodiment, the construction management means 10 of the above embodiment was used to prevent the automatic injection from being stopped, and the other operations were performed under the same conditions. In this other embodiment, the injection is stopped when the injection pressure reaches 70% of the breaking pressure of the bag 1a. Then, after the injection was stopped, confirmation was performed based on the bag body diameter expansion confirmation method according to the present embodiment. That is, after the injection was stopped, the relationship between the grout injection amount and the injection pressure was graphed on a personal computer and confirmed. As a result, it was confirmed that it passed through the inflection point C during the injection, and it was determined that the grout injection was stopped in the state where the bag body 1a was sufficiently expanded in the hole.

The embodiment of the present invention is not limited to the above description, but may be modified as follows, for example. (1) In the present embodiment, an example in which the grout injection pump is automatically stopped based on a command from the controller provided in the construction management means has been described. However, the transition of the injection pressure and the injection amount displayed in real time is described. By visually observing the graph shown, it is possible to grasp that the inflection point C has been passed,
The construction manager may stop the grout injection pump by himself. Also in this case, the injection can be stopped immediately after passing through the inflection point C.

(2) In the present embodiment, an example was described in which the horizontal axis represents the grout injection amount and the vertical axis represents the grout injection pressure. However, this is not necessarily the case, and for example,
The grout injection amount and the injection pressure may be graphed separately. Also in this case, the same effect as the present invention can be obtained.

(3) The relationship between the injection pressure and the injection amount when the grout is injected into the bag body in the air, not in a state where the bag body is inserted into the soil (drilling) prior to the grout injection work. In advance, and based on this measurement result, the inflection point C
May be determined. FIG. 6 shows the results of a comparative experiment in which the bag 1a used in the above example was injected with grout in air and in soil, where the horizontal axis represents the time from the start of injection and the vertical axis represents Is shown as the injection pressure. In this comparative experiment, the injection rate was changed from that in the above-mentioned example, but the injection rate was constant.

As shown in FIG. 6, in the case of injection in the air (solid line in the figure), the position corresponding to the inflection point C generated during injection in the soil (dotted line in the figure) (FIG. Among them, the time axis shows the correspondence, but the supply amount also corresponds), and there is a tendency that the pressure rise becomes remarkable. this is,
It is thought that this is because the amount of injection that the fibers of the bag begin to become tense is close to the air and the soil. Therefore, by measuring the relationship between the injection amount of grout and the injection pressure in the air in advance and grasping the injection amount at which the pressure rise becomes remarkable, it is possible to estimate the injection amount in the soil (during drilling) in advance. Inflection point C during injection at
It is possible to accurately estimate the injection amount that occurs. Accordingly, when the construction manager determines the inflection point C on the real-time display graph, the inflection point C can be more accurately determined.

(4) The grout injection method according to the present invention is
In addition to the use of expanding in the ground as in the present embodiment, "Japanese Patent Laid-Open No. 2000-45260: Ground reinforcement", "Japanese Patent Application No. 11-356793: Pile with a bag attached only to the tip, jack for supporting work""Japanese Patent Application Laid-Open No. 9-4389: Justification of segment back surface", "Japanese Patent Application No. 2001-127708: Adjustment of unevenness of slope", "Japanese Patent Application Laid-Open No. 8-109633: Justification of abdomen and ground", "Japanese Patent Publication No. -6208: Correction of unequal settlement of buildings "," Japanese Patent Application No. 11-356793: Jack of support work "," Japanese Patent Application Laid-Open No. 11-350494: Horizontal horizontal beam ",
"JP-A-11-304300: Bag-filled concrete columns"
Etc. can be widely used for the method of injecting grout into the bag body.

[0054]

According to the first aspect of the present invention, the injection state of grout into the bag can be grasped by controlling the grout injection pressure into the bag. That is, when the grout is injected into the bag, the bag is filled with the grout, the bag is filled with the grout and then the diameter is expanded while the ground is being expanded, and the bag is sufficiently expanded. The fiber undergoes various states such as the state where the fiber is under tension, but these states can be grasped by managing the change in the injection pressure.
Thereby, it is possible to easily confirm that the bag body is sufficiently expanded in the drilling hole to the extent that the bag buried object can exhibit a desired function, and it is possible to appropriately determine the grout injection stop timing. .

According to the second aspect of the present invention, first, it is possible to grasp the timing at which the fibers of the bag body start to be tensioned after the bag body expands the ground sufficiently while expanding the ground by the grout filling the bag body. . That is, when the rate of change of the grout injection pressure once decreases, it is possible to grasp the timing when the grout is filled in the bag body, and when it starts to increase again later, the bag body pushes the ground and expands sufficiently. It is possible to grasp that the fibers of the bag have begun to be tense by expanding the diameter. Then, by stopping the injection of grout before reaching the critical pressure at which the bag breaks, it is possible to inject the grout until the function as a bag buried object can be fully exerted without damaging the bag. You will be able to

According to the third aspect of the invention, it is possible to more accurately grasp the state of grout injection in the bag body.
That is, since the change in the grout injection pressure is largely influenced by the volume of the bag, the change in the injection pressure with respect to the change in the grout injection amount is managed to more clearly understand the change in the injection pressure. be able to.

According to the invention of claim 4, when the injection stop timing judged from the change in the grout injection pressure comes, the injection stop can be immediately dealt with, and the injection can be stopped at an appropriate timing. .

According to the fifth aspect of the present invention, it is possible to prevent the human error from occurring in the judgment of the grout injection stop timing and the stop operation, and to reliably perform the construction management.

According to the invention of claim 6, even when the surrounding ground is particularly hard or, conversely, when the ground is very soft, even if the change in the grout injection pressure is difficult to appear clearly, the bag body The grout injection can be stopped without causing damage to the grout.

According to the seventh aspect of the present invention, even if the bag body is damaged without a change in the grout injection pressure being apparent, the outflow of the grout to the surrounding ground can be suppressed. You can Therefore, an efficient grout injection method can be provided in terms of environment and economy.

According to the invention of claim 8, the bag is expanded sufficiently while the bag is expanding the ground by the grout filled in the bag, and then the grout injection is stopped after the fiber of the bag starts to be tensioned. Can be confirmed after grout injection. That is, it can be confirmed after the completion of construction that the bag body is sufficiently expanded in the drilling hole to the extent that the bag body embedded article can exhibit a desired function.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an outline of construction management means for implementing a grout injection method according to an embodiment.

FIG. 2 shows an example of an embedded bag body to which the grout injection method according to the present embodiment is applied.

FIG. 3 is a diagram illustrating a procedure for constructing a bag anchor.

FIG. 4 is a graph for managing changes in injection pressure in the grout injection method according to the present embodiment.

FIG. 5 is a graph showing the relationship between the grout injection pressure and the injection amount according to the present embodiment.

FIG. 6 is a diagram showing a comparison of changes in grout injection pressure into a bag in air and in soil.

[Explanation of symbols]

1, 2 bag buried object 1a, 2a bag 1b, 2b grout 1d, 2d rebar injection pipe 3 drilling 4 mixing pumps 5 injection hose 6 sensor unit 7 amplifier 8 controller 10 Construction management means A, B, C inflection point E ground

Claims (8)

[Claims] 1. A method of injecting grout into a bag body when the bag body is inserted into a hole drilled in the ground and the grout is injected into the bag body to be an embedded object. A grout injection method characterized in that the timing of stopping the grout injection is judged by managing the change of the injection pressure when performing. 2. The injection of grout is stopped after the rate of change of the injection pressure once decreases and then increases again and before the critical pressure at which the bag body breaks is reached. The grout injection method according to claim 1. 3. The grout injection method according to claim 1, wherein the change of the injection pressure is a change of the injection pressure managed with respect to the change of the grout injection amount. 4. The injection pressure change is managed while being displayed in real time during injection.
The grout injection method according to any one of 3 above. 5. The automatic determination means is used to detect when the rate of change of the injection pressure is once decreased and then is increased again, and is automatically stopped after the detection. 5. The grout injection method according to any one of 4 to 4. 6. The grout injection according to claim 1, wherein an upper limit value of the injection pressure is set, and when the injection pressure upper limit value is reached, the grout injection is stopped. Method. 7. The grout injection according to claim 1, wherein an upper limit value of the grout injection amount is set, and when the injection amount upper limit value is reached, the grout injection is stopped. Method. 8. A bag body for confirming that the bag body is expanded in a desired amount when the bag body is inserted into a hole drilled in the ground and grout is injected into the bag body to be a buried object. It is a method of confirming the diameter expansion, and after the grout injection is completed, it is confirmed that there is a point in time when the rate of change of the injection pressure when the grout was injected into the bag body was once decreased and then increased again. In this way, it is confirmed that the bag body is expanded by a desired amount.