JP2017014829A - Chemical solution injecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical solution injecting method capable of injecting a chemical solution while quantitatively grasping an injection effect of the chemical solution.SOLUTION: A chemical solution injecting method injects a chemical solution into the foundation by dynamically changing a chemical solution injection speed. The method comprises: a process to determine an optimal amplitude value to increase and decrease the chemical solution injection speed for a target foundation into which the chemical solution is injected; a process to determine a dynamic coefficient d calculated from the amplitude coefficient α, which made a relationship between an average injection speed and the optimal amplitude dimensionless, and a frequency f of increase and decrease; and a process to inject the chemical solution based on the relationship between the dynamic coefficient d and the injection effect.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chemical solution injection method for injecting a chemical solution into the ground.

  As disclosed in Patent Document 1, there is known a chemical solution injection method in which the injection rate or injection pressure of a chemical solution is dynamically changed and injected into the ground. According to this dynamic injection method, it is possible to widen the permeation range of the chemical solution and to improve the ground efficiently.

  On the other hand, Patent Document 2 discloses a method capable of confirming the liquefaction countermeasure effect of the ground with simple experimental equipment in consideration of the strength of the improved body itself with respect to the ground improved by the chemical injection. Has been.

  Patent Document 3 discloses a chemical solution injection method in which a chemical solution injection speed or injection pressure is dynamically changed and injected into a viscous ground, and a split vein is formed in the viscous ground.

Japanese Patent No. 3731189 JP 2004-84392 A JP 2000-64266 A

  However, in the method of Patent Document 2, since the ground is repeatedly collected during the improvement and the quality is confirmed, the standby time increases and the construction period becomes longer. On the other hand, if the injection effect by the chemical injection can be quantitatively evaluated by a simple method, the chemical injection method with a high improvement effect can be easily applied.

  Then, this invention aims at providing the chemical | medical solution injection | pouring method which can be implemented after grasping | ascertaining quantitatively the injection | pouring effect of a chemical | medical solution.

  In order to achieve the above object, the chemical solution injection method of the present invention is a chemical solution injection method in which the injection rate or injection flow rate of the chemical solution is dynamically changed and injected into the ground, and the injection rate or injection flow rate of the chemical solution is controlled. A step of determining an optimum value of the amplitude to be increased / decreased for the target ground to which the chemical solution is injected, an amplitude coefficient α obtained by making the relationship between the average injection speed or flow rate and the optimal amplitude dimensionless, and the frequency f of the increase / decrease The method includes a step of determining a dynamic coefficient d obtained by calculating and a step of injecting a chemical solution based on a relationship between the dynamic coefficient d and an injection effect.

  Here, the injection effect is expressed based on the volume consolidated by the injected chemical solution when the target ground is sandy ground, and the chemical injection when the target ground is viscous ground It can be made to be expressed based on the number of split veins formed by.

  The optimum amplitude is preferably determined based on a result of a test in which the amplitude of the water injection is changed on the target ground.

  The chemical solution injection method of the present invention configured as described above is based on the dynamic coefficient d obtained by calculating the non-dimensional relationship between the average injection speed or average injection flow rate and the optimum amplitude, and the frequency f, and the injection effect. The chemical solution is injected under the conditions set using the relationship between

  For this reason, the injection | pouring effect of a chemical | medical solution can be grasped | ascertained quantitatively. If the injection effect of the chemical solution can be grasped quantitatively, it is possible to carry out the implementation by taking advantage of the construction method having a high injection effect, such as expanding the construction pitch of the injection pipe.

  Such injection effects are quantified by conducting an experiment in advance and using an indicator of the volume consolidated by chemicals for sandy ground and the number of split veins formed by chemical injection for viscous ground. Can be made.

  Furthermore, when determining the optimum amplitude, it is possible to estimate the injection effect with high accuracy by performing a test in which the amplitude of the water injection is changed on the target ground.

It is the figure which showed the relationship between the dynamic coefficient d in a sandy ground, and an injection | pouring effect, in order to demonstrate the chemical | medical solution injection | pouring method of embodiment of this invention. It is explanatory drawing which showed typically the structure of the apparatus used for a chemical | medical solution injection | pouring. It is explanatory drawing for demonstrating a limit injection rate test. It is explanatory drawing for demonstrating the method to determine the optimal amplitude. It is the figure which showed the relationship between the dynamic coefficient d in a viscous ground, and an injection effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the relationship between the dynamic coefficient d and the injection effect in the sandy ground for explaining the chemical injection method according to the present embodiment.

  On the other hand, FIG. 2 is a diagram showing a schematic configuration of an apparatus used in the chemical injection method of the present embodiment. First, the structure of the dynamic infusion pump 2 and its surroundings will be described with reference to FIG.

  As a preparation process for injecting the chemical solution, the injection pipe 1 is installed on the ground G using the boring machine 4. Here, when the injection tube 1 also serves as a drilling rod, the swivel head 11 of the boring machine 4 is connected to the head of the injection tube 1, and the injection tube 1 driven into the target ground is used as a chemical solution. Used for injection.

  On the other hand, when a dedicated drilling rod (not shown) is used, the drilling rod is first connected to the swivel head 11 of the boring machine 4, and the drilling rod is injected after the drilling is completed. It replaces with the pipe | tube 1 and will perform chemical | medical solution injection | pouring.

  The swivel head 11 is connected to a dynamic infusion pump 2 capable of performing a chemical liquid injection method of increasing or decreasing the chemical liquid injection speed, injection flow rate, or injection pressure with time. That is, the dynamic injection pump 2 is a pump capable of dynamic injection that changes the injection speed, the injection flow rate, or the injection pressure over time.

  The dynamic infusion pump 2 is mainly composed of an infusion pump 21 having an electric motor as a drive unit, a waveform generator 22 serving as a function generator, and a flow rate / pressure measuring device 23.

  The injection pump 21 can change the discharge flow rate (injection flow rate) by arbitrarily changing the rotation speed of the electric motor. Here, the value obtained by dividing the discharge flow rate by the cross-sectional area of the pipe used for feeding the chemical solution is the injection speed.

  For this reason, when the rotation speed of the electric motor is lowered, the injection speed is lowered accordingly. On the other hand, when the rotational speed of the electric motor is increased, the injection speed is increased accordingly.

  The waveform generator 22 is a device that creates a control waveform such as a SIN wave (sine wave), for example. The waveform generator 22 can adjust the frequency f and the amplitude B of the waveform. Here, the amplitude B is a difference between the maximum injection rate and the minimum injection rate (difference between the maximum flow rate and the minimum flow rate, difference between the maximum injection pressure and the minimum injection pressure).

  Furthermore, the flow rate / pressure measurement device 23 is a device that measures the flow rate and injection pressure of the chemical solution injected into the target ground (ground G) by the injection tube 1. From the flow rate value (L / min) measured by the flow rate / pressure measuring device 23, the injection flow rate (injection speed) of the chemical solution injected into the target ground can be grasped.

  In addition, the underground pressure can be estimated from the pressure value (kPa) measured by the flow rate / pressure measuring device 23. For example, when the pressure value measured by the flow rate / pressure measuring device 23 is increasing, it can be estimated that the underground pressure in the target ground is also increasing.

  The chemical solution injected by the dynamic injection pump 2 includes known chemical solution injection methods such as water glass solution type chemical solution, bentonite, high-concentration fine grout containing ultrafine cement, and mortar grout mixed with coarse particles. Various kinds of chemicals used in the above can be used.

  In addition, depending on the type of the chemical liquid to be injected, there are a liquid that is pumped immediately after mixing the two liquids and a liquid that is pumped in the state of one liquid. In FIG. 2, the structure which pumps immediately after mixing two liquids (A liquid, B liquid) is demonstrated.

  A chemical liquid mixer 3 is connected to the dynamic infusion pump 2. In the chemical liquid mixer 3, two liquids (A liquid and B liquid) are mixed. That is, the hardener (the raw material of the B liquid) conveyed from the hardener storage site 31, the water sent from the water storage tank 32, and the solution (A liquid) sent from the liquid storage tank 33 are contained in the chemical liquid mixer 3. Mix with.

  The curing material storage 31 is appropriately replenished with the curing material that has been carried to the site by the transport vehicle 311 or the like. Further, the water stored in the water storage tank 32 is supplied to the chemical mixer 3 by the water pump 321.

  Further, the solution transported by the tank lorry 333 or the like is stored in the liquid storage tank 33 and supplied to the chemical liquid mixer 3 by the liquid feed pump 331. Here, the amount of the solution supplied to the chemical mixer 3 is managed by the flow meter 332.

  Next, the chemical solution injection method of the present embodiment will be described in order.

  First, the limit injection speed in the target ground where the chemical solution is injected is obtained. The limit injection rate is a value at which it is said that a sufficient improvement effect can be obtained if the chemical injection method is less than this value.

  Various methods have been proposed for determining the limit injection rate. For example, it can be obtained from the result of an in-situ test (limit injection rate test) in which water is injected into the ground G.

  FIG. 3 is a conceptual diagram for explaining the limit injection rate test. When water is injected into the ground G, an ST1 interval in which the injection pressure increases linearly in proportion to the injection speed appears first. This ST1 section is considered to be mainly composed of osmotic injection, and the straight line of the initial gradient in this section is LN1.

  The relationship between the injection speed and the injection pressure in the ST2 section following the ST1 section is such that the injection pressure gradually decreases after reaching a gentle parabolic peak. This decrease in the injection pressure is considered to be caused by splitting of the ground G due to the increase in pore water pressure.

  Therefore, a straight line LN2 having a gradient of 30% of the initial gradient of the straight line LN1 is drawn from the origin, and divided into the ST2 section and the ST3 section at a position where it intersects the curve. This ST3 section is a section in which split injection is the main part, and ST2 section is a section in a transition state from osmotic injection to split injection. Then, the injection speed that becomes the boundary between the ST2 section and the ST3 section is determined as the limit injection speed LS0.

  Subsequently, an optimum value of the amplitude for increasing or decreasing the injection speed (or injection flow rate) of the chemical liquid is determined for the target ground on which the chemical liquid injection is performed. The optimum amplitude is determined based on the result of a test in which the amplitude of the water injection is changed on the target ground. If the limit injection speed and the optimum amplitude are obtained for each target ground, the nonuniformity of the ground can be taken into consideration.

  In order to perform these tests, first, as shown in FIG. 2, the injection tube 1 is driven to a predetermined depth of the ground G using a boring machine 4. Then, using this injection tube 1, a limit injection rate test for injecting water into the target ground is performed to obtain a limit injection rate LS0.

  Further, a water injection test is performed from the injection tube 1 to increase or decrease the injection rate over time. Here, if the cross-sectional area of the pipe used for water pumping is constant, the change in the injection rate is the same as the change in the injection flow rate (L / min).

  FIG. 4 is an explanatory diagram conceptually showing the result of the water injection test. The water injection test is performed with the average injection rate S0 set to the limit injection rate LS0. Further, the amplitude B for increasing / decreasing the injection rate is gradually increased as time t elapses.

  On the other hand, the injection pressure P indicating the underground pressure of the ground G during the water injection is measured by the flow rate / pressure measuring device 23 and illustrated as shown in the lower part of FIG. As shown in this figure, when the water injection is continued, the gap between the ground G is filled with water, so that the injection pressure P gradually increases.

  However, when the injection pressure P increases to a certain extent, a situation occurs in which the pressure rapidly decreases. This is thought to be due to a new splitting in the target ground due to an increase in the injection pressure P and a decrease in pressure.

Here, an amplitude coefficient α obtained by making the amplitude B dimensionless at the average injection speed S0 is defined. That is, the amplitude coefficient α can be expressed by the following equation.
Amplitude coefficient = (maximum injection rate−minimum injection rate) / average injection rate ie α = B / S0

  Then, the generation time of the injection pressure P1, which is the apex immediately before the injection pressure P suddenly decreases, is defined as t1. Further, the difference between the maximum injection speed S1 and the minimum injection speed S2 at the time t1 is set as the optimum amplitude B1 of the target ground. In short, the amplitude B immediately before split injection is the main component becomes the optimum amplitude B1.

Therefore, a value obtained by making the optimum amplitude B1 dimensionless by the average injection speed S0 is set as an optimum amplitude coefficient α1.
Optimal amplitude coefficient (α1) = optimal amplitude (B1) / average injection rate (S0) (1)

On the other hand, a management index using the amplitude coefficient α and the frequency f as parameters is defined as a dynamic coefficient d.
d = F (α, f) = α × f (2)

  FIG. 1 is a diagram in which the results of experiments conducted by injecting chemicals into the target ground, which is sandy ground, are organized. This experiment was conducted on several target grounds. In addition to dynamic injection, experiments using static injection (constant rate injection with an average injection rate) were also conducted for comparison.

The confirmation of the injection effect of the chemical solution in the sandy ground is expressed based on the volume of the ground solidified by the injected chemical solution. Here, the consolidation volume formed by dynamic injection is V, and the consolidation volume formed by static injection is V ₀ .

Then, a consolidated volume ratio RV (= V / V ₀ ) between dynamic injection and static injection is calculated as an experimental result performed on each target ground. Further, the amplitude coefficient α and the frequency f of the dynamic injection when the result of each consolidated volume V is obtained are recorded.

  In FIG. 1, the dynamic coefficient d, which is the product of the amplitude coefficient α and the frequency f, is plotted on the horizontal axis, and the consolidated volume ratio RV indicating the comparison result of the dynamic injection and static injection is plotted on the vertical axis. The relationship between the dynamic coefficient d and the consolidated volume ratio RV is shown.

Therefore, when the relational expression was derived by the least square method based on the plotted experimental results, the following expression was derived.
RV = K · d + 1 = 1.19d + 1 (3)

  From the results shown in FIG. 1, it can be seen that the consolidated volume is larger in the dynamic injection than in the static injection. That is, it can be seen that by performing dynamic injection, the injection effect of improving the permeability of the chemical solution and expanding the penetration range can be obtained. Further, as an injection effect, a quantitative evaluation can be performed such that an increase of about 20% of the consolidated volume can be expected at d = 0.168.

  On the other hand, FIG. 5 is a diagram summarizing the results of experiments conducted by injecting chemicals into the target ground, which is a viscous ground. In this experiment, not only dynamic injection but also static injection was performed for comparison.

Confirmation of the injection effect of the chemical solution in the viscous ground is expressed based on the number of split veins formed in the ground by the injected chemical solution. Here, the number of split裂脈formed by dynamic infusion is N, the number of split裂脈formed by the static injected N _0.

Then, the ratio RN (= N / N ₀ ) of the split veins of dynamic injection and static injection is calculated as the result of the experiment performed on the target ground. Further, the amplitude coefficient α and the frequency f of the dynamic injection when the result of the number N of split veins is obtained are recorded.

  FIG. 5 shows the dynamic coefficient d, which is the product of the amplitude coefficient α and the frequency f, on the horizontal axis, and the ratio RN of split veins showing the comparison results of the dynamic injection and static injection effects on the vertical axis. The relationship between the dynamic coefficient d and the split ratio RN number ratio RN is shown.

Therefore, when the relational expression was derived by the least square method based on the plotted experimental results, the following expression was derived.
RN = K · d + 1 = 14.6d + 1 (4)

  From the results shown in FIG. 5, it can be seen that the number of split veins increases in the dynamic injection compared to the static injection. That is, it can be seen that by performing dynamic injection, an injection effect is obtained in which the split pulse rate increases and a strong and uniform composite ground can be constructed. In addition, the injection effect can be quantitatively evaluated so that an increase of about 40% of the split pulse rate can be expected at d = 0.027.

  Therefore, chemical injection using such quantitative evaluation is performed. First, as shown in FIG. 2, the injection tube 1 is driven to a predetermined depth of the ground G using a boring machine 4. Although not shown in the figure, a large number of injection pipes 1,... Are actually installed on the ground G with a wide area.

  And the chemical | medical solution will be inject | poured in the ground G using the installed injection tube 1. FIG. At this time, the optimum amplitude coefficient α1 has been found as described above for the target ground into which the chemical solution is injected.

  On the other hand, the waveform generator 22 usually adjusts the frequency f at 1 Hz or less. For example, it is assumed that the target ground is sandy ground, the limit injection speed is 10 (L / min), and the optimum amplitude coefficient α1 is determined to be 0.5 by the water injection test.

  When these values are applied to the above equation (1), the optimum amplitude B1 of the injection rate is 5 (L / min). When the frequency f is set to 0.1 Hz, the dynamic coefficient d is 0.05. When this dynamic coefficient d is applied to the above equation (3), the consolidation volume ratio RV is 1.06, and it is found that the injection effect can be improved by 6% compared with the static injection.

  Here, it is assumed that the construction pitch of the injection pipes 1... Is designed based on the injection effect of static injection. In such a case, if it can be quantitatively shown that the injection effect is improved by 6% by dynamic injection, the construction pitch can be expanded accordingly.

  Then, the injection tube 1 performs injection with the injection speed increased or decreased over time with the optimum amplitude B1. Here, if the cross-sectional area of the pipe used for feeding the chemical liquid is constant, the change in the injection speed is the same as the change in the injection flow rate (L / min).

  For this reason, “managing with the injection rate” and “managing with the injection flow rate (discharge flow rate)” can be synonymous. Therefore, the injection rate can be managed by the measurement value of the flow rate / pressure measurement device 23.

  The average injection speed S0 can be adjusted by changing the number of rotations of the injection pump 21. The average injection rate S0 is set to a limit injection rate LS0 = 10 (L / min) here.

  On the other hand, the increase / decrease in the injection rate is adjusted by the waveform generator 22. That is, a sine wave having a difference between the maximum injection rate S1 and the minimum injection rate S2 as an amplitude (optimal amplitude B1 = 5 (L / min)) is used as a control waveform. The waveform generator 22 also sets the frequency f (0.1 Hz).

Next, the effect | action of the chemical injection method of this Embodiment is demonstrated.
The chemical solution injection method of the present embodiment configured as described above is based on the dynamic coefficient d obtained by calculating the optimum amplitude coefficient α1 and the frequency f obtained by making the relationship between the average injection speed S0 and the optimum amplitude B1 dimensionless, and the injection effect. The chemical solution is injected under the conditions set using the relationship between

  For this reason, the injection | pouring effect of a chemical | medical solution can be grasped | ascertained quantitatively. If the injection effect of the chemical solution can be grasped quantitatively, it is possible to carry out an implementation taking advantage of the construction method having a high injection effect, such as increasing the construction pitch of the injection pipes 1.

  Such an injection effect can be quantitatively shown by a solidification volume V or a solidification volume ratio RV consolidated by a chemical solution in the case of sandy ground by conducting an experiment in advance. In the case of a viscous ground, it can be quantified using an index called the number N of split veins or the ratio RN of split veins formed by chemical injection.

  Furthermore, when determining the optimum amplitude B1, it is possible to estimate the injection effect with high accuracy by performing a test in which the amplitude B by water injection is changed on the target ground.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the above-described embodiment, the case where the injection management is performed at the injection speed has been described. However, the present invention is not limited to this, and the injection management can be similarly performed according to the injection flow rate.

  In the above-described embodiment, the case where the injection speed is increased or decreased with a sine wave has been described. However, the present invention is not limited to this, and various waveforms such as a rectangular waveform and a sawtooth waveform can be used as the control waveform.

  Furthermore, in the above-described embodiment, the dynamic coefficient d is expressed as a product of the amplitude coefficient α and the frequency f. However, the present invention is not limited to this, and the function F calculated using the amplitude coefficient α and the frequency f is not limited thereto. (Α, f) may be used.

  In the above-described embodiment, the method for determining the optimum amplitude B1 and the optimum amplitude coefficient α1 by performing a test by water injection on the target ground for chemical injection has been described, but the method is not limited thereto. When there is a ground result similar to the target ground, the optimum amplitude B1 and the optimum amplitude coefficient α1 can be determined using values obtained from the ground.

G ground α amplitude coefficient α1 optimal amplitude coefficient B1 optimal amplitude f frequency d dynamic coefficient RV consolidation volume ratio (injection effect)
RN number ratio (injection effect)
S0 Average injection rate S1 Maximum injection rate S2 Minimum injection rate

Claims (3)

A chemical solution injection method for dynamically changing the injection rate or flow rate of a chemical solution and injecting it into the ground,
Determining the optimum value of the amplitude for increasing or decreasing the injection speed or injection flow rate of the chemical solution for the target ground to be injected with the chemical solution;
Determining a dynamic coefficient d obtained by calculating an amplitude coefficient α obtained by making a non-dimensional relationship between an average injection speed or an average injection flow rate and the optimum amplitude, and the increase / decrease frequency f;
A chemical solution injection method comprising a step of injecting a chemical solution based on the relationship between the dynamic coefficient d and the injection effect.   The injection effect is expressed based on the volume consolidated by the injected chemical when the target ground is sandy ground, and formed by chemical injection when the target ground is viscous ground. The chemical injection method according to claim 1, wherein the chemical injection method is expressed based on the number of split veins.   The said optimal amplitude is determined based on the result of having performed the test which changed the magnitude | size of the amplitude by water injection with respect to the target ground, The chemical | medical solution injection construction method of Claim 1 or 2 characterized by the above-mentioned.