JP6942521B2 - Chemical injection device and ground injection method - Google Patents

Description

The present invention relates to a chemical solution injection device and a ground injection method used for ground improvement work.

In recent years, various techniques for improving the ground have been provided. As the ground injection method to be constructed at the time of ground improvement, for example, in addition to the strainer injection method in which the chemical solution is injected through a large number of injection ports formed on the peripheral surface of the strainer injection pipe, a binding thin pipe built in the drilled part is used. Uses a binding thin tube multi-point injection method that injects chemicals using it, or an inner tube (injection pipe) with a packer built inside an outer tube (for example, a pipe called a manchette tube) inserted in the drilled part. Then, a double pipe double packer method for injecting a chemical solution can be mentioned.

The injection form of the chemical solution to be injected into the ground for ground improvement is, for example, "osmosis injection" in which the pore water is permeated so as to replace the chemical solution (injection solution or grout material) without moving the soil particles in the ground, and the soil particles are injected. It is roughly divided into "split injection" in which the drug solution is injected while moving. In "split injection", the chemical solution is injected into the part other than the improved range, and there is a possibility that an unimproved part may occur in the improved range. Ideally, it should be injected within the improved range of. Therefore, when improving the ground, the chemical solution is statically injected at a low pressure so that the chemical solution is in a state of "penetration injection" into the ground.

In the ground injection method such as the strainer injection method and the double pipe double packer method described above, it is common to inject into the improved range until the injection amount of the chemical solution reaches a predetermined injection amount while keeping the injection rate constant. Is the target. Further, in recent years, as a ground injection method for ground such as cracked rock containing a large number of microcracks, a dynamic method of injecting a chemical solution by superimposing a pulsating pressure having a specific frequency or several kinds of frequencies on the injection pressure. The effectiveness of the target injection method has been confirmed (see Patent Documents 1 to 3).

For example, in Patent Document 1, when a cement or bentonite-based chemical solution (grout material) is injected into a cracked bedrock, a pulsating pressure having a specific frequency selected from a frequency range of 5 to 30 Hz is superimposed on the injection pressure. In addition to, a technique for exciting constituent particles of a drug to improve permeability is disclosed. Further, in Patent Document 2, in grouting in which a chemical (grout material) is injected into cracked rock and sandy ground that is uniform in the vertical and horizontal directions, the injection pressure is a long wave of 0.04 to 0.08 Hz and a long wave of 1 to 6 Hz. Disclosed is a technique for improving the permeability by superimposing the pulsating pressure due to the complex wave of the short wave of the above to excite the constituent particles of the chemical solution. Further, Patent Document 3 describes "split injection" by increasing or decreasing the injection rate in a cycle of 7 to 15 seconds and increasing the maximum value and the minimum value of the injection pressure each time the injection rate is repeatedly increased or decreased. It discloses a technique for suppressing the occurrence and efficiently infiltrating the injection material into the target range.

Furthermore, in recent years, in addition to the dynamic injection method, the injection pressure generated when the drug solution is injected is dissipated by repeating the process of suspending the injection of the drug solution for a predetermined time and then injecting the drug solution again, so that "split injection" is performed. An inching injection method for suppressing the occurrence of "" has also been devised (see Patent Document 4).

Japanese Patent No. 3096244 Japanese Patent No. 5089430 Japanese Patent No. 3757400 Japanese Unexamined Patent Publication No. 2015-25293

However, for example, in the double-tube double packer method, when the chemical solution is injected, the pore water pressure between the injection positions tends to increase, and "split injection" tends to occur. When "split injection" occurs, the ground rises due to the injection pressure of the chemical solution, so it is necessary to interrupt the injection of the chemical solution and dissipate the injection pressure of the chemical solution remaining in the ground. Therefore, in the double pipe double packer method, there is a problem that the work efficiency (availability) is deteriorated and the construction period related to the ground improvement is lengthened. Double pipe When considering that the construction period for ground improvement is to be carried out in a short period of time using the double packer method, it is conceivable to inject the chemical solution into multiple positions (hereinafter referred to as the injection position) at the same time, but the double pipe In the double packer method, the above-mentioned "split injection" is likely to occur, so it is unlikely to be a solution to shorten the construction period related to ground improvement.

Further, in the dynamic injection method and the inching injection method, the average injection rate of the chemical solution is set to be slower than the injection rate of the chemical solution in the double tube double packer method, so that the occurrence of "split injection" can be suppressed. However, in these construction methods, the injection rate of the chemical is set to be slower than that in the double pipe double packer construction method, so that the construction period for ground improvement is prolonged as in the double pipe double packer construction method. When the drug solution is injected into a plurality of injection positions at the same time in these construction methods, the peak (maximum value) of the injection rate of the drug solution injected into each injection position may coincide in time. When the peak (maximum value) of the injection rate of the chemical solution injected at each injection position coincides in time, the injection pressure of the chemical solution becomes high, and the above-mentioned "split injection" occurs. Therefore, even in the case of the dynamic injection method and the inching injection method, injecting the chemical solution into a plurality of injection positions at the same time is unlikely to be a solution for shortening the construction period for ground improvement.

An object of the present invention is to provide a chemical injection device and a ground injection method for reliably improving the ground in a short period of time without splitting the ground.

According to one viewpoint, the chemical injection device of the present invention switches between an injection outer pipe having a plurality of chemical liquid discharge ports for discharging the chemical liquid, an injection inner pipe inserted into the injection outer pipe, and a flow path of the chemical liquid. In a chemical injection device having a flow path switching device, the injection inner pipe is arranged between two expandable packer rubbers provided at predetermined intervals and the two packer rubbers to discharge the chemical liquid. It has a plurality of packer mechanisms having a discharge port, and a connecting rod provided between two adjacent packer mechanisms among the plurality of packer mechanisms and connecting the two adjacent packer mechanisms. Of the two adjacent packer mechanisms, the packer mechanism located above includes a first flow path for feeding the chemical solution toward the discharge port of the packer mechanism located above, and a packer mechanism located below. A packer located below the packer having a second flow path for feeding the chemical solution toward the surface and a third flow path for feeding air inside the two packer rubbers of the packer mechanism located above the packer mechanism. The mechanism is a fourth flow path for feeding the chemical solution toward the discharge port of the packer mechanism located below, and a fifth flow path for sending air inside the two packer rubbers of the packer mechanism located below. When the two adjacent packer mechanisms are connected via the connecting rod, the connecting rod communicates with the second flow path and the fourth flow path. The flow path switching device has a sixth flow path, a seventh flow path that communicates the third flow path and the fifth flow path, and the flow path switching device allows the chemical solution to flow through the first flow path. A device that switches the flow path of the chemical solution so as to flow into either the path or the fourth flow path, and the first after the injection speed of the chemical solution flowing into the first flow path becomes a constant speed. When the time elapses, the flow path of the chemical solution is switched so that the chemical solution flows into the fourth flow path, and after the injection speed of the chemical solution flowing into the fourth flow path becomes a constant rate, the second When the time elapses, the chemical solution operates to switch the flow path of the chemical solution so that the chemical solution flows into the first flow path .

Further, the maximum outer diameter of the packer mechanism located above is larger than the maximum outer diameter of the packer mechanism located below .

Further, the connecting rod is an adjusting member capable of adjusting the distance from the discharge port provided in one of the two adjacent packer mechanisms to the discharge port provided in the other packer mechanism. It is a feature.

According to the present disclosure, it is possible to obtain a reliable ground improvement effect in a short period of time without splitting the ground.

It is a block diagram which shows an example of the structure of the construction system of this invention. It is a perspective view which shows an example of the structure of the injection tube which the chemical liquid injection apparatus has. It is an xz cross-sectional view of the 1st packer. It is a cross-sectional view of yz of the 1st packer. It is an xz cross-sectional view of the 2nd packer. It is an xz cross-sectional view of the connecting rod. It is a flowchart which shows the flow of building an injection outer pipe. It is a figure which shows an example of the process of assembling the injection outer pipe. It is a graph which shows the injection method of a chemical solution. It is a graph which shows the time change of the discharge rate in the injection pump, and the time change of the injection rate of the drug in the flow path A and the flow path B when the injection amount of the drug solution at the two injection positions is the same. It is a flowchart which shows the flow of injecting a chemical solution. It is a figure which shows the flow at the time of injecting a chemical solution into two adjacent injection positions. It is a figure which shows the flow at the time of injecting a chemical solution into two injection positions different from FIG. In the graph which shows the time change of the discharge rate in the injection pump and the time change of the injection rate of the drug in the flow path A and the flow path B when the full opening time of the flow path is set to a different time for each flow path. be. In the graph which shows the time change of the discharge rate in the injection pump and the time change of the injection rate of the drug in the flow path A and the flow path B when the discharge amount of the injection pump is set to a different discharge amount for each flow path. be.

Hereinafter, this embodiment will be described with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a construction system that implements the ground injection method of the present invention. Note that in FIG. 1, the configuration of the drilling machine and the control unit that controls the drilling machine is omitted. As shown in FIG. 1, the construction system 10 of the present embodiment includes a dynamics management device 11, an injection management device 12, a recording PC 13, and a chemical solution injection device 20.

The dynamic control device 11 receives measurement data from the measuring instruments 15 installed at a plurality of locations on the ground from the recording PC 13, and uses the received measurement data to limit the rotation speed of the injection pump 21 of the chemical solution injection device 20. , Make a stop instruction judgment. The dynamic control device 11 sequentially compares the regulation value and the measurement data, and when the measurement data exceeds the regulation value, the injection management device 12 is instructed to regulate the multiplication factor between 0 and 99%. conduct. The multiplication factor can be changed by the injection pump 21.

The injection control device 12 is connected to the dynamic control device 11 in a local area. The injection management device 12 acquires measurement data of flow rate pressure, instantaneous flow rate, and integrated flow rate from the flow rate / pressure measuring device 16, and displays the measurement data of flow rate pressure, instantaneous flow rate, and integrated flow rate on a monitor or the like.

The injection management device 12 is connected to the inverter 22 included in the chemical injection device 20, and transmits an ON / OFF signal to the injection pump 21 and a frequency control signal to the inverter 22. Further, when the dynamic control device 11 transmits a limit / stop instruction signal (multiplier) for the rotation speed of the injection pump 21, the injection control device 12 multiplies the set flow rate by the injection flow rate of the injection pump 21. The frequency control signal is output to the inverter 22 so as to be a numerical value. Further, the injection management device 12 drives the flow path switching device 23 of the chemical solution injection device 20 based on the measurement data of the flow rate pressure, the instantaneous flow rate, and the integrated flow rate acquired from the flow rate / pressure measuring device 16 to drive the chemical solution. Switch the flow path.

The recording PC 13 acquires measurement data from the measuring instrument and displays stress and displacement data at the time of injection of the chemical solution on a monitor or the like. Further, the recording PC 13 records the measurement data and transmits the measurement data to the dynamics management device 11.

The measuring instruments 15 are provided at a plurality of locations on the ground and measure stress and displacement of the ground during injection of a chemical solution.

The flow rate / pressure measuring device 16 is provided on, for example, a hose connecting the injection pump 21 and the injection pipe 24, and measures the injection amount and pressure of the delivered chemical solution and the like.

The chemical injection device 20 includes an injection pump 21, an inverter 22, a flow path switching device 23, an injection pipe 24, and the like. The injection pump 21 is provided, for example, between the grout mixer and the flow rate / pressure measuring device 16, and sends the drilling water toward the injection pipe 24 at the time of drilling the chemical solution. The inverter 22 drives and controls the injection pump 21. As an example, the flow path switching device 23 is a switching valve that switches the flow path of the chemical solution from the injection pump 21 by electronic control.

As shown in FIG. 2, the injection tube 24 has an injection outer tube 31 and an injection inner tube 32. The injection outer tube 31 is, for example, a manchette tube used in the double tube double packer method. The injection outer pipe 31 is provided with a discharge port 34 at regular intervals (L1 in FIG. 2) in the longitudinal direction. In FIG. 2, as an example, a case where the discharge ports 34 are provided at four locations in the longitudinal direction of the injection outer pipe 31 is shown. The distance L1 between adjacent discharge ports 34 is, for example, 500 mm. The discharge ports 34 are arranged on the outer peripheral surface of the injection outer pipe 31 at intervals of, for example, 90 degrees. The discharge ports 34 provided at four locations in the longitudinal direction of the injection outer pipe 31 are shielded by the rubber sleeves 35 attached to the injection outer pipe 31. Although not shown, the rubber sleeve 35 is fixed to one end side of the injection outer tube 31 in the longitudinal direction by a binding band. The inner diameter of the injection outer tube 31 is 40 mm as an example.

The rubber sleeve 35 is elastically deformed by the pressure received from the injected chemical solution, and is between the discharge port 34 and the open end of the rubber sleeve 35 (the end opposite to one end fixed by the binding band). Create a gap. By forming this gap, the chemical solution is discharged radially. Further, by closing the discharge port 34 of the injection outer pipe 31, the rubber sleeve 35 is pressed against the discharge port 34 against external pressure and comes into close contact with the rubber sleeve 35, so that backflow to the injection outer pipe 31 from the outside and water Prevent intrusion.

Next, the configuration of the injection inner tube 32 will be described with reference to FIGS. 2 to 6.
As shown in FIGS. 2 to 6, the injection inner tube 32 includes a first packer (corresponding to a packer mechanism) 41, a second packer (corresponding to a packer mechanism) 42, and a connecting rod connecting these packers 41 and 42 (corresponding to the packer mechanism). It has (corresponding to an adjusting member) 43.

As shown in FIGS. 3 and 4, the first packer 41 includes an upper packer 55, a lower packer 56, and a nozzle 57. The upper packer 55 has two chemical liquid pipes (inner pipes) 81 and 82 to which the chemical liquid is sent, and an outer pipe 83 for accommodating these chemical liquid pipes 81 and 82 inside.

Of these pipes, the outer pipe 83 has its upper end fixed to the holding member 84 by, for example, screwing. In a state where the outer pipe 83 is fixed to the holding member 84, the two chemical liquid pipes 81 and 82 are held by the holding member 84 at one end on the upper end side. The holding member 84 is a cylindrical member. The holding member 84 holds two chemical solution adapters 86 and 87 and an air adapter 88 on the upper surface. Therefore, in a state where one end on the upper end side of the two chemical liquid tubes 81 and 82 is held by the holding member 84, the chemical liquid adapter 86 and the chemical liquid pipe 81 are communicated with each other, and the chemical liquid adapter 87 and the chemical liquid pipe 82 are connected to each other. Communicate. Further, the holding member 84 has a through hole 89 communicating with the air adapter 88. Although not shown, in a state where the holding member 84 is fixed to the outer pipe 83, a gap is provided in a part between the holding member 84 and the outer pipe 83. Therefore, the air flowing in from the air adapter 88 is sent into the gap and the inside of the outer pipe 83 through the through hole 89.

The support member 90 is a cylindrical member. The support member 90 is fixed to the holding member 84 by, for example, screwing. The support member 90 sandwiches the upper end portion of the packer rubber 59 with the stopper 91. In the state where the support member 90 is fixed to the holding member 84, the support member 90 forms a gap with the outer pipe 83. Therefore, the air flowing into the gap between the holding member 84 and the outer pipe 83 is sent into the gap generated between the support member 90 and the outer pipe 83.

The holding member 92 is held on the outer peripheral surface on the lower end side of the outer pipe 83. The holding member 92 holds the support member 94 that sandwiches the lower end portion of the packer rubber 59 with the stopper 93 on the upper side.

The nozzle 57 is fixed to the holding member of the lower packer 56. The nozzle 57 has a tubular body 98 and a flow path forming member 99. The tubular body 98 fixes the lower end portion of the outer pipe 83 constituting the upper packer 55 by, for example, screwing. The tubular body 98 has four discharge ports 62 on the outer peripheral surface, for example, at intervals of 90 °. The flow path forming member 99 is housed inside the tubular body 98, and the two chemical liquid tubes 81 and 82 constituting the upper packer 55 are fixed. The flow path forming member 99 has two passages 100 and 101. The passage 100 is a passage for flowing the chemical solution sent into the inside of the chemical solution pipe 81 toward the discharge port 62 of the tubular body 98 when the flow path forming member 99 is housed inside the tubular body 98. Become. The passage 101 is a passage for delivering the chemical solution sent into the inside of the chemical solution pipe 82 toward the second packer 42 when the flow path forming member 99 is housed inside the tubular body 98. Reference numeral 102 is a connecting pipe, and the connecting pipe 102 communicates with the passage 101 included in the flow path forming member 99.

Further, when the flow path forming member 99 is housed inside the tubular body 98, a passage 103 that sends the air sent from the outer pipe 83 toward the lower packer 56 is provided between the flow path forming member 99 and the tubular body 98. It is formed.

The lower packer 56 has a chemical solution pipe 105, an outer pipe 106, and holding members 107, 108, 109.

The holding member 107 is a columnar member. The holding member 107 fixes the tubular body 98 of the nozzle 57 at the upper end and the upper end of the outer tube 106 at the lower end. In the state where the outer pipe 106 is fixed to the holding member 107, the chemical liquid pipe 105 is held by the holding member 107 at one end on the upper end side. The holding member 107 has a through hole 110 communicating with the connecting pipe 102 and a through hole 111 communicating with the passage 103 formed inside the nozzle 57.

Therefore, in a state where the upper end portion of the chemical liquid pipe 105 is held by the holding member 107, the connecting pipe 102 and the chemical liquid pipe 105 are communicated with each other. Further, although not shown, in a state where the holding member 107 is fixed to the outer tube 106, a gap is provided in a part between the holding member 107 and the outer tube 106. As a result, the air sent through the through hole 111 of the holding member 107 is sent into the gap provided between the holding member 107 and the outer pipe 106 and the inside of the outer pipe 106.

The holding member 107 fixes the cylindrical support member 112 on the lower side. The support member 112 is a member that sandwiches and holds the upper end portion of the packer rubber 61 with the stopper 113. Here, when the support member 112 is fixed to the holding member 107, a gap is formed between the support member 112 and the outer tube 106. Therefore, the air flowing through the gap provided between the holding member 107 and the outer pipe 106 is sent into the gap formed between the support member 112 and the outer pipe 106. Therefore, the packer rubber 61 of the lower packer 56 expands.

The holding member 108 is held on the outer peripheral surface on the lower end side of the outer pipe 106. The holding member 108 holds the support member 115 that sandwiches the lower end portion of the packer rubber 61 with the stopper 114 on the upper side.

The holding member 109 fixes the lower end of the outer pipe 106. In a state where the lower end of the outer tube 106 is fixed to the holding member 109, the chemical solution tube 105 is held by the holding member 109. The holding member 109 has a through hole 109a and sends air flowing inside the outer pipe 106 toward the connecting rod 43. The connecting member 116 is fixed to the holding member 109. The outer tube of the connecting rod 43 is fixed. In the internal space of the connecting member 116, the holding member 109 has a connecting member 117 into which the inner tube 141 of the connecting rod 43 is inserted. The connecting member 117 is a member that communicates the chemical liquid pipe 105 with the inner pipe 141 of the connecting rod 43.

As shown in FIG. 5, the second packer 42 has an upper packer 71, a lower packer 72, and a nozzle 73. The upper packer 71 has a chemical solution tube 120 and holding members 121 and 122. The holding member 121 fixes the connecting rod 43 on the upper end side and the support member 123 on the lower end side. The holding member 121 has a connecting member 124 that communicates with the inner pipe 141 of the connecting rod 43. Further, the holding member 121 holds the upper end portion of the chemical liquid pipe 120 on the lower surface side. When the chemical liquid pipe 120 is held by the holding member 121, the chemical liquid pipe 120 and the connecting member 124 are communicated with each other. Therefore, the chemical solution flowing down the connecting member 124 is sent into the chemical solution pipe 120. Further, the holding member has a through hole 125. Here, when the support member 123 is fixed to the holding member 121 and the holding member 121 holds the chemical liquid pipe 120, a gap is formed between the support member 123 and the chemical liquid pipe 120. As a result, the air flowing through the through hole 125 is sent into the gap formed between the support member 123 and the chemical solution pipe 120. The support member 123 sandwiches the upper end portion of the packer rubber 75 with the stopper 126. Therefore, the packer rubber 75 expands due to the air sent.

The holding member 122 holds the lower end portion of the chemical liquid pipe 120 and fixes the support member 127. The holding member 122 has a through hole 128 penetrating from the upper surface side to the lower surface side. Further, in a state where the holding member 122 holds the chemical liquid pipe 120, a gap is formed between the support member 127 and the chemical liquid pipe 120, and these through holes 128 communicate with the gap. Therefore, the air flowing between the chemical liquid pipe 120 and the support member is sent to the lower packer 72 through the through hole 128.

The nozzle 73 is a member fixed to the holding member 122. The nozzle 73 has a discharge port 78 for discharging the chemical solution flowing through the chemical solution pipe. Discharge ports 78 are provided at four locations at intervals of 90 degrees in the circumferential direction. The nozzle 73 has a through hole 129, and sends the air sent from the through hole 128 of the holding member 122 to the lower packer 72.

The lower packer 72 has a connecting pipe 131 and support members 132, 133. The connecting pipe 131 is a tubular member. The connecting pipe 131 sends the air sent from the through hole 129 of the nozzle 73 into the packer rubber 77. The connecting pipe 131 sandwiches and holds the upper end portion of the packer rubber 77 with the stopper 134. The support member 133 sandwiches and holds the lower end portion of the packer rubber 77 with the stopper 135. Reference numeral 136 is a cap, and the cap 136 fixes the support member. As a result, the air flowing inside the connecting pipe 131 expands the packer rubber 77 through the gap between the support member 132 and the support member 133.

As shown in FIG. 6, the connecting rod 43 is arranged between the first packer 41 and the second packer 42. The connecting rod 43 has an inner pipe 141 and an outer pipe 142. Although details are omitted, the outer tube 142 holds the inner tube 141 inside so as to be coaxial. The upper end of the outer pipe 142 of the connecting rod 43 is fixed to the connecting member 116 of the lower packer 56 of the first packer 41. At this time, the inner pipe 141 of the connecting rod 43 is connected to the connecting member 117 of the holding member 109 of the lower packer 56.

The lower end of the outer tube 142 of the connecting rod 43 is fixed to the holding member 121 of the second packer 42. At this time, in the inner pipe 141 of the connecting rod 43, the connecting member 143 provided at the lower part of the inner pipe 141 is fitted with the connecting member 124 held by the holding member 121 of the upper packer 71 of the second packer 42.

Here, the passage formed by the chemical liquid adapter 86, the chemical liquid pipe 81, the passage 100 of the flow path forming member 99, and the discharge port 62 corresponds to the first flow path. Further, the chemical liquid adapter 87, the chemical liquid pipe 82, the passage 101 of the flow path forming member 99, the connecting pipe 102, the through hole 110, the chemical liquid pipe 105, the connecting member 117, the inner pipe 141, the connecting member 143, the connecting member 124, and the chemical liquid pipe. The flow path formed by 120 and the holding member 122 corresponds to the second flow path.

Further, the air adapter 88, the through hole 89 of the holding member 84, the gap provided in a part between the holding member 84 and the outer pipe 83, the gap generated between the support member 90 and the outer pipe 83, and the chemical liquid pipe 81. , 82 and the gap between the outer pipe 83, the passage formed in the nozzle 57, the through hole 111 provided in the holding member 107, the partially generated gap between the holding member 107 and the outer pipe 106, and the support member 90 and the outside. The passage formed by the gap formed between the pipe 83 and the pipe 83 corresponds to the third flow path.

Further, the flow path formed by the connecting member 124 and the chemical liquid pipe 120 included in the holding member 121 corresponds to the fourth flow path.

Further, the through hole 125 of the holding member 121, the gap formed between the chemical liquid pipe 120 and the support member 123, the gap formed between the chemical liquid pipe 120 and the support member 127, the through hole 128 of the holding member 122, and the nozzle 73 The passage formed by the through hole 129, the connecting pipe 131, and the support member 132 having the through hole 129 corresponds to the fifth flow path.

Further, the passage formed by the inner pipe 141 of the connecting rod 43 corresponds to the sixth passage. The gap between the inner pipe 141 and the outer pipe 142 of the connecting rod 43 corresponds to the seventh flow path.

The connecting rod 43 described above is used by using any one rod of rods having a plurality of different lengths (for example, 1 m, 2 m, 3 m) or a combination of a plurality of rods. Therefore, the connecting rod 43 can adjust the distance L2 between the discharge port 62 of the nozzle 57 of the first packer 41 and the discharge port 70 of the nozzle 67 of the second packer 42. It is also possible to connect the first packer 41 and the second packer 42 without using the connecting rod 43. FIG. 2 shows a case where the first packer 41 and the second packer 42 are connected by using a connecting rod 43 having a length of 315 mm as an example. In this case, the distance L2 between the discharge port 62 of the nozzle 57 of the first packer 41 and the discharge port 70 of the nozzle 67 of the second packer 42 is 1000 mm.

Although not shown, the injection inner tube 32 described above has a maximum outer diameter of the first packer 41 set to be larger than the maximum outer diameter of the second packer 42. Specifically, the maximum outer diameter of the first packer 41 is 35 mm, and the maximum outer diameter of the second packer 42 is 29.5 mm.

Next, an example of the step of assembling the injection outer pipe 31 will be described with reference to FIGS. 7 and 8.

Step S101 is a drilling step. For example, a casing pipe 171 and a rod 172 are used to drill a hole at a position to be targeted for ground improvement (see FIG. 8A). This step is carried out by a drilling machine (not shown).

Step S102 is a step of filling the sealing material. The injection pipe 173 is inserted into the casing pipe 171 and the gel-like sealing material 174 is filled inside the casing pipe 171 (see FIG. 8B).

Step S103 is an insertion step of the injection outer tube 31. In step S102, after filling the inside of the casing pipe 171 with the gel-like sealing material 174, the injection outer pipe 31 is inserted into the inside of the casing pipe 171 (see FIG. 8C).

Step S104 is a casing drawing step. After inserting the injection outer pipe 31 into the casing pipe 171, the casing pipe 171 is pulled out. Then, the gel-like sealing material 174 is cured until it hardens (see FIG. 8D).

After that, the injection inner tube 32 is inserted into the injection outer tube 31, and a process of injecting the chemical solution is performed.

Next, a method of injecting a drug solution will be described. As a method of injecting the drug solution, as shown in FIG. 9, static injection in which the drug solution is injected at a constant injection rate, or pulsating pressure having a specific frequency or several kinds of frequencies is superimposed on the injection pressure. In addition to the dynamic injection for injecting the drug solution, there is an inching injection (intermittent injection) in which the operation of injecting the drug solution and the operation of suspending the injection of the drug solution are repeated. In the ground injection method of the present invention, the chemical solution is alternately injected into each of the two injection positions by inching injection, and the chemical solution is simultaneously injected into the two injection positions. The middle dotted line in FIG. 9 shows the injection pressure when the inching injection is performed.

First, a case where the injection amount of the drug solution injected into the two injection positions is the same will be described. Hereinafter, of the two injection positions, the flow path provided for one of the injection positions will be referred to as the flow path A, and the flow path provided for the other injection position will be referred to as the flow path B.

As shown in FIG. 10, in the step of injecting the chemical solution into the ground, the injection management device 12 operates the injection pump 21. When the injection pump 21 is driven, the chemical solution is discharged from the injection pump 21 and the chemical solution flows into either the flow path A or the flow path B. For example, when the flow path switching device 23 is set so that the chemical solution flows into the flow path A, when the injection pump 21 is driven, the chemical solution flows into the flow path A. When the injection speed of the chemical solution discharged from the injection pump 21 becomes a constant speed, the injection speed in the flow path A also becomes a constant speed. When the time T1 (fully open time T1) elapses after the injection speed in the flow path A becomes a constant speed, the injection management device 12 drives the flow path switching device 23, and the flow path through which the chemical liquid flows flows from the flow path A. Switch to B. In the process of switching the flow path through which the chemical solution flows from the flow path A to the flow path B, the injection speed of the chemical solution flowing into the flow path A decreases, while the injection rate of the chemical solution flowing into the flow path B increases from 0. Then, when the flow path through which the chemical solution flows is switched from the flow path A to the flow path B, the injection speed of the chemical solution flowing into the flow path A becomes 0, and the injection speed of the chemical solution flowing into the flow path B becomes a constant speed.

Then, when the time T2 (fully open time T1 = T2) elapses after the injection speed in the flow path B becomes a constant speed, the injection management device 12 drives the flow path switching device 23, and the flow path B through which the chemical solution flows flows. To switch to flow path A. In the process of switching the flow path into which the chemical solution flows from the flow path B to the flow path A, the injection speed of the chemical solution flowing into the flow path B decreases, while the injection rate of the chemical solution flowing into the flow path A increases from 0. Then, when the flow path through which the chemical solution flows is switched from the flow path B to the flow path A, the injection speed of the chemical solution flowing into the flow path B becomes 0, and the injection speed of the chemical solution flowing into the flow path A becomes a constant speed.

The operation of switching the flow path by the flow path switching device 23 described above is repeatedly executed until the injection amount of the chemical solution with respect to the two injection positions reaches the target injection amount. Then, when the injection amount of the drug solution with respect to the two injection positions reaches the target injection amount, the injection management device 12 stops the drive of the injection pump 21.

The step of injecting the above-mentioned chemical solution is repeatedly executed.

As shown in FIG. 10, in the method of injecting a chemical solution, the injection speed in the injection pump 21 is constant, and the chemical solution is injected into each of the two injection positions while switching between the two flow paths. Therefore, in the process of injecting the drug solution using the flow path A, the drug solution is not injected using the flow path B. As a result, since the peaks of the injection speeds when each flow path is used do not match, it is possible to prevent the occurrence of split injection due to the injection pressure generated in the ground. Further, since the increase in the injection pressure of the chemical solution can be suppressed even when the flow path is switched by the flow path switching device 23, it is possible to prevent the occurrence of split injection due to the injection pressure generated in the ground.

Hereinafter, the position of the discharge port 34 provided in the injection outer pipe 31 in the longitudinal direction of the injection outer pipe 31 fixed to the ground by hardening of the sealing material is referred to as an injection position. Hereinafter, as shown in FIG. 12A, each injection position will be described with reference numerals P ₁ , P ₂ , P ₃ , and P ₄ from the surface side of the ground. In the following, a case of injecting a chemical solution while pulling up the injection inner pipe 32 from the deepest side of the ground, that is, a so-called step-up method, will be described. It may be the case of the step-down method in which the chemical solution is injected while lowering the pressure. Examples of the chemical solution to be injected into the ground include a water glass-based solution type chemical solution (injection material) and an ultrafine spherical silica injection material having excellent permeability.

As shown in FIG. 11, the step of injecting the chemical solution is the following step.

Step S201 is a step of inserting the injection inner tube into the injection outer tube. The injection inner tube 32 is inserted into the injection outer tube 31 fixed to the ground by curing, and the injection inner tube 32 is inserted to the target injection position.

Step S202 is a step of sending air to the air pipe. The injection pump 21 is driven to send air to the first packer 41 and the second packer 42 via the air adapter 88. As a result, the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 expand.

Step S203 is a step of injecting a chemical solution. The injection pump 21 is used to alternately inject the chemical solution into the 86 and the chemical solution adapter 87. As a result, the drug solution is injected into two different injection positions. As an example, the injection step of the chemical solution is executed in the order of 1st injection, stop of the injection pump 21, and 2nd injection. Here, the pump stop time between the 1st injection and the 2nd injection is about ten and several seconds to several minutes. When this process is executed, the air in the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 is depressurized, and these packer rubbers are contracted.

Step S204 is a process of determining whether or not the drug solution is injected at all the injection positions. When the drug solution is injected at all the injection positions, the determination process in step S204 is Yes. Therefore, the process shown in FIG. 11 ends. In this case, the injection inner tube 32 is pulled out from the injection outer tube 31. On the other hand, when the drug solution is not injected at all the injection positions, the determination process in step S204 is No. In this case, the process proceeds to step S205.

Step S205 is a step of adjusting the position of the injection inner tube. In this case, the injection inner tube 32 is pulled up until the target injection position is reached. When this process is executed, the process returns to step S202.

The injection position for injecting the drug solution will be described below.

<Example 1>
As shown in FIG. 12 (a), injecting a chemical liquid injection position of the two positions adjacent to the injection position P ₃ and an injection position P _4. In this case, the injection inner pipe 32 is used by directly connecting the first packer 41 and the second packer 42 without using the connecting rod 43. Even if the injection position P ₃ and the injection position P ₄ are adjacent to each other, when the first packer 41 and the second packer 42 are directly connected, the discharge port of the nozzle 57 of the first packer 41 is provided. 62 and the distance L2 to the discharge port 78 of the second packer 42 has a nozzle 73 is shorter than the distance L1 between the injection position _{P 3} and an injection position _{P 4} includes a first packer 41 and the second packer 42 It is possible to attach and use the connecting rod 43 between the two.

As shown in FIG. 12 (b), injecting the tube 32 is inserted into the injection outer tube 31, the discharge port 62 is injection position _{P 3} of the nozzle 57 with the first packer 41, a nozzle 73 in which the second packer 42 has until the discharge port 78 coincides with the injection position P _4, injected into tube 32 is inserted into the infusion outer tube 31. Since the outer diameter of the second packer 42 is smaller than the outer diameter of the first packer 41, the injection inner tube 32 is inserted into the injection outer tube 31 or the injection inner tube 32 with respect to the injection outer tube 31. It is possible to suppress the frictional resistance between the injection inner pipe 32 and the injection outer pipe 31 when the injection inner pipe 32 is raised and lowered when the position of the injection inner pipe 32 is adjusted.

After inserting the injection inner pipe 32, air is sent to the first packer 41 and the second packer 42 via the air adapter 88. As a result, in the first packer 41, the packer rubber 59 of the upper packer 55 and the packer rubber 61 of the lower packer 56 expand respectively. At the same time, in the second packer 42, the packer rubber 75 of the upper packer 71 and the packer rubber 77 of the lower packer 72 expand respectively. Since the maximum outer diameter of the first packer 41 is larger than the maximum outer diameter of the second packer 42, the packer rubbers 59 and 61 of the first packer 41 are the packer rubbers 75 of the second packer 42. , 77 is brought into close contact with the inner wall surface of the injection outer tube 31 before.

As shown in FIGS. 12 (b) and 12 (c), the chemical solution is alternately injected into the chemical solution adapter 86 and the chemical solution adapter 87. Thus, the chemical liquid from the discharge port of the infusion outer tube 31 positioned between the injection position P ₃ in the injection position P ₄ is penetrated into the soil. As an example, the injection of the drug solution is executed in the order of 1st injection, stop of the injection pump 21, and 2nd injection. After injecting the chemical solution, the air sent to the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 is depressurized to shrink each packer rubber.

After each packer rubber is contracted, pulling the infusion inner tube 32, a discharge port 62 to the injection position P ₁ of the nozzle 57 in which the first packer 41 has, injection position the discharge opening 78 of the nozzle 73 to the second packer 42 has Match P _2. After the injection inner pipe 32 is pulled up, air is sent to the first packer 41 and the second packer 42 via the air adapter 88. As a result, each of the packer rubbers of the first packer 41 and the second packer 42 is expanded by the air sent in, and the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 are formed. Each of them comes into close contact with the inner wall surface of the injection outer tube 31 (see FIG. 12 (d)).

In this state, the chemical solution is alternately injected into the chemical solution adapter 86 and the chemical solution adapter 87. Thus, the chemical liquid from the discharge port 34 of the infusion outer tube 31 positioned to the injection position P ₁ and the injection position P ₂ is penetrated into the soil. As shown in FIGS. 12 (d) and 12 (e), the injection of the drug solution is executed in the order of 1st injection, pump stop, and 2nd injection.

Then, after injecting the chemical solution, the air sent to the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 is depressurized to shrink each packer rubber, and the injection inner tube 32 is inserted. Pull up.

As described above, the maximum outer diameter of the first packer 41 is larger than the maximum outer diameter of the second packer 42. Therefore, when the packer rubbers are contracted, the packer rubbers 75 and 77 of the second packer 42 contract before the packer rubbers 59 and 61 of the first packer 41.

When the injection pump 21 is stopped, the chemical solution remains inside each pipe of the chemical solution adapter 86 and the chemical solution adapter 87, and even when the injection pump 21 is stopped, the chemical solution is discharged from the nozzle 57 at the discharge port 62. And the discharge port 78 of the nozzle 73. As described above, the packer rubbers 75 and 77 of the second packer 42 shrink before the packer rubbers 59 and 61 of the first packer 41. As a result, a space for flowing the chemical solution can be secured between the second packer 42 and the injection outer tube 31. Therefore, when the chemical solution remaining in the vicinity of the discharge port 62 of the nozzle 57 of the first packer 41 flows from the discharge port 62 into the inside of the injection outer tube 31, the chemical solution is retained up to the upper end of the injection inner tube 32. Can be prevented. As a result, when the injection inner tube 32 is pulled up, the event that the cured chemical solution is caught between the packer and the injection outer tube 31 can be prevented, and the resistance when the injection inner tube 32 is pulled up can be suppressed. It becomes.

<Example 2>
In Example 1, has been described a case of injecting the chemical solution injection position of the two positions adjacent, as shown in FIG. 13, the drug solution in two injection positions of the injection position P ₂ and an injection position P ₄ after the injection, it may be carried out injection of the drug solution at two injection positions of the injection position P ₁ and the injection position P _3. In this case, the injection inner tube 32 is used with the connecting rod 43 mounted between the first packer 41 and the second packer 42.

FIG. 13 (a) and 13 as shown in FIG. 13 (b), injecting the tube 32 is inserted into the injection outer tube 31, the discharge port 62 is injection position _{P 2} of the nozzle 57 first packer 41 has a second the discharge port 78 of the nozzle 73 which packer 42 has the match the injection position _{P 4.} After inserting the injection inner pipe 32, air is sent to the first packer 41 and the second packer 42 via the air adapter 88. As a result, in the first packer 41, the packer rubber 59 of the upper packer 55 and the packer rubber 61 of the lower packer 56 expand respectively. At the same time, in the second packer 42, the packer rubber 75 of the upper packer 71 and the packer rubber 77 of the lower packer 72 expand respectively. Since the maximum outer diameter of the first packer 41 is larger than the maximum outer diameter of the second packer 42, the packer rubbers 59 and 61 of the first packer 41 are the packer rubbers 75 of the second packer 42. , 77 is brought into close contact with the inner wall surface of the injection outer tube 31 before.

As shown in FIGS. 13 (b) and 13 (c), the chemical solution is alternately injected into the chemical solution adapter 86 and the chemical solution adapter 87. Thus, the chemical liquid from the discharge port of the infusion outer tube 31 positioned to the injection position P ₂ and the injection position P ₄ is penetrated into the soil. As an example, the injection of the drug solution is executed in the order of 1st injection, stop of the injection pump 21, and 2nd injection.

After performing 1st injection, pump stop, and 2nd injection using the discharge port 34 of the injection outer pipe 31 at the injection position P ₂ and the injection position P ₄ , the packer rubbers 59, 61 and the second packer rubber 59, 61 and the second packer 41 of the first packer 41 have. The packer rubbers 75 and 77 of the packer 42 are contracted.

After shrinking the packer rubber, pulling the infusion inner tube 32, a discharge port 62 to the injection position P ₁ of the nozzle 57 in which the first packer 41 has, injection position the discharge opening 78 of the nozzle 73 to the second packer 42 has P Match ₃ After the injection inner pipe 32 is pulled up, air is sent to the first packer 41 and the second packer 42 via the air adapter 88. As a result, each of the packer rubbers of the first packer 41 and the second packer 42 is expanded by the air sent in, and the packer rubbers 59 and 61 of the first packer 41 and the packer rubbers 75 and 77 of the second packer 42 are formed. Each of them comes into close contact with the inner wall surface of the injection outer tube 31 (see FIG. 13 (d)).

In this state, the drug solution is alternately injected into the first drug solution tube and the second drug solution tube. Thus, the chemical liquid from the discharge port 34 of the infusion outer tube 31 positioned to the injection position P ₁ and the injection position P ₂ is penetrated into the soil. As shown in FIGS. 13 (d) and 13 (e), the injection of the drug solution is executed in the order of 1st injection, pump stop, and 2nd injection. After injecting the chemical solution, the packer rubbers of the first packer 41 and the second packer 42 are contracted, and then the injection inner tube 32 is pulled up.

In this case as well, the same effect as in Example 1 can be obtained.

In the above-described embodiment, the case where the injection amount of the chemical solution to be injected at the two injection positions is the same is described, but the injection amount of the chemical solution depends on the injection position where the chemical solution is injected due to the structure of the ground. May differ depending on the injection position. Hereinafter, a case where the chemical solution is injected into two injection positions where the injection amount of the chemical solution injected through the flow path A is twice the injection amount of the chemical solution injected through the flow path B will be described.

As shown in FIG. 14, in the step of injecting the chemical solution into the ground, the injection management device 12 operates the injection pump 21. When the injection pump 21 is driven, the chemical solution discharged from the injection pump 21 flows into the flow path A. When the time T3 (fully open time T3) elapses after the injection speed in the flow path A becomes a constant speed, the injection management device 12 drives the flow path switching device 23, and the flow path through which the chemical liquid flows flows from the flow path A. Switch to B. Then, when the time T4 (fully open time T4 = T3 / 2) elapses after the injection speed in the flow path B becomes a constant speed, the injection management device 12 drives the flow path switching device 23 to flow the flow path through which the chemical solution flows. Switch from road B to flow path A. As a result, the flow path through which the chemical solution flows is switched from the flow path B to the flow path A. In this case as well, the operation of the injection pump 21 is stopped after the above processing is repeatedly executed until the injection amount of the drug solution for the two injection positions reaches the target injection amount.

As a result, the injection amount of the chemical solution to be injected is different from the injection amount at each injection position of the injection position where the drug solution is injected through the flow path A and the injection position where the drug solution is injected through the flow path B. It becomes possible to do.

When the drug solution is injected into two injection positions where the injection amount of the drug solution injected through the flow path A is twice the injection amount of the drug solution injected through the flow path B, the injection time of each flow path is set. Based on this, the flow path into which the chemical solution is poured is switched, but the rotation speed when the injection pump 21 is driven is adjusted (specifically, the discharge speed (or discharge amount) from the injection pump 21 is changed). Therefore, the injection amount of the chemical solution injected through the flow path A and the injection amount of the chemical solution injected through the flow path B may be different injection amounts.

As shown in FIG. 15, in the step of injecting the chemical solution into the ground, the injection management device 12 operates the injection pump 21. When the injection pump 21 is driven, the chemical solution discharged from the injection pump 21 flows into the flow path A. When the time T5 (fully open time T5) elapses after the injection speed in the flow path A becomes a constant speed, the injection management device 12 drives the flow path switching device 23, and the flow path through which the chemical liquid flows flows from the flow path A. Switch to B. For example, when the injection pump 21 is driven to reach half the maximum speed of the chemical solution flowing into the flow path A, the rotation speed of the injection pump 21 is reduced to 1/2. Then, when the time T6 (fully open time T6 = T5) elapses after the injection speed in the flow path B becomes a constant speed, the injection management device 12 drives the flow path switching device 23, and the flow path B through which the chemical solution flows flows. To switch to flow path A. At the same time, the rotation speed of the injection pump 21 is doubled. In this case as well, the operation of the injection pump 21 is stopped after the above processing is repeatedly executed until the injection amount of the drug solution for the two injection positions reaches the target injection amount.

The above-mentioned full opening time is adjusted according to the soil quality of the ground. Therefore, the fully open time when injecting the drug solution into the flow path A and the fully open time when injecting the drug solution into the flow path B may be set to the same time or may be set to different times. ..

In the present embodiment, the injection inner tube having two packers, the first packer 41 and the second packer 42, is taken as an example, but the number of packers in the injection inner tube may be three or more. ..

In the present embodiment, the drug solution injection device having the injection tube 24 composed of the injection outer tube 31 and the injection inner tube 32 has been described, but the drug solution injection device having only the injection inner tube 32 of the present embodiment as the injection tube. You may.

In the present embodiment, the case where the chemical solution is injected into two injection positions among the plurality of injection positions having different depths is described, but the injection outer pipes are built and built in at a plurality of positions on the ground. By inserting the injection inner tube into any two of the injection outer tubes, it is possible to inject the drug solution into two injection positions.

10 ... construction system, 20 ... chemical injection device, 21 ... injection pump, 24 ... injection pipe, 31 ... injection outer pipe, 32 ... injection inner pipe, 41 ... first packer, 42 ... second packer, 43 ... connecting rod, 55,71 ... Upper packer, 56,72 ... Lower packer, 57,73 ... Nozzle, 59,61,75,77 ... Packer rubber, 62,78 ... Discharge port, 86,87 ... Chemical solution adapter, 88 ... For air adapter

Claims (3)

In a chemical solution injection device having an injection outer tube having a plurality of chemical solution discharge ports for discharging chemical solutions, an injection inner tube inserted into the injection outer tube, and a flow path switching device for switching the flow path of the chemical solution.
The injection inner tube
A plurality of packer mechanisms having two expandable packer rubbers provided at predetermined intervals and a discharge port arranged between the two packer rubbers to discharge the chemical solution.
Of the plurality of packer mechanisms, a connecting rod provided between two adjacent packer mechanisms and connecting the two adjacent packer mechanisms,
Have,
Of the two adjacent packer mechanisms, the packer mechanism located above is
A first flow path for feeding the chemical solution toward the discharge port of the packer mechanism located above, a second flow path for feeding the drug solution toward the packer mechanism located below, and a second flow path located above the chemical solution. A third flow path for sending air inside the two packer rubbers of the packer mechanism, and
Have
The packer mechanism located below is
A fourth flow path for feeding the chemical solution toward the discharge port of the packer mechanism located below, and a fifth flow path for sending air inside the two packer rubbers of the packer mechanism located below. When,
Have,
The connecting rod
When the two adjacent packer mechanisms are connected via the connecting rod, the sixth flow path that communicates the second flow path and the fourth flow path, and the third flow path. A seventh flow path communicating with the fifth flow path and
Have,
The flow path switching device is
A device that switches the flow path of the chemical solution so that the chemical solution flows into either the first flow path or the fourth flow path.
When the first time elapses after the injection speed of the chemical solution flowing into the first flow path becomes constant, the flow path of the chemical solution is switched so that the chemical solution flows into the fourth flow path.
When the second time elapses after the injection speed of the chemical solution flowing into the fourth flow path becomes constant, the flow path of the chemical solution is switched so that the chemical solution flows into the first flow path.
A chemical injection device characterized in that it operates in such a manner. In the chemical injection device according to claim 1,
A chemical injection device characterized in that the maximum outer diameter of the packer mechanism located above is larger than the maximum outer diameter of the packer mechanism located below. In the drug solution injection device according to claim 1 or 2.
The connecting rod
A chemical injection device characterized by being an adjusting member capable of adjusting the distance from a discharge port provided in one of the two adjacent packer mechanisms to a discharge port provided in the other packer mechanism.

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