JP5278856B2 - Ground improvement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inject a chemical liquid independently in required points in a support foundation of an existing building, to enhance a local consolidation degree of a ground by forming a solidified structure in a required part of a soil under the support foundation of a structure, and to enhance a ground proof stress to stably support the structure reasonably. <P>SOLUTION: A chemical liquid injection rod 3 is inserted in a required position, in a lower foundation soil of a base 1 of the structure, an instantaneously solidified chemical liquid material is pumped in intermittently while applying a load due to the base 1 as a mount load by the chemical liquid injection rod 3, a homogeneous gel part of a solidified body 20a injected previously to be under solidification is brokenly cracked by the post-injected chemical liquid material, the chemical liquid material is infiltrated into a peripheral soil of the solidified body 20a, the breaking cracking and/or the infiltration are repeated further, the solidified structure 20 by the chemical liquid material and a soil particle is formed in a lower side of the base 1, a foundation soil is consolidated independently by the solidified structure 20, to enhance the ground proof stress. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention independently injects a chemical injection material into the soil under the support base of the structure in a required distribution, increases the pressure density at the important points of the soil, and strengthens the ground strength against the support base, thereby stabilizing the ground. This is related to the ground improvement method.

  As a means to strengthen the foundation soil that supports the structure, in addition to injecting chemicals into the soil to increase the pressure density and strengthen the soft ground, to prevent uneven settlement of the ground due to soil liquefaction, etc. The chemical injection method is adopted. In this chemical injection method, a known chemical solution material is pressed into the soil with a chemical solution injection rod of a known structure, and the pressure density of the soil is increased in a wide range by combining the injected chemical solution material with the sand grains in the soil, and the ground is improved. For example, Patent Document 1 discloses a technique for improving the ground by such chemical injection.

  In addition, as a method of applying a chemical solution injection method to restore a structure inclined on unevenly subsidized ground, there is a method (restoration method) known from Patent Document 2, for example. In this restoration method, the chemical injection rod is inserted and arranged at multiple intervals in the soil below the foundation of the structure, and the operation of injecting the instantaneously setting chemical liquid material at the chemical injection site by the chemical injection rod, This injection operation is repeated by sequentially switching from one chemical injection site to the next chemical injection site at a required interval to split the homogel portion of the chemical solution previously injected at each injection location, and further around the homogel portion. The reaction force is increased by forming a solidified structure that is expanded by injecting chemicals into the soil of the soil, increasing the ground strength and pushing up the structure on the base, restoring the inclined structure to normal There is to let it be. Further, in the chemical solution injection method implemented in the above manner, a plurality of types of chemical solution materials having different gelation times are used for the chemical solution injection material to be injected. A method of performing an injection operation by switching alternately is known from Patent Document 3.

  However, the chemical solution injection method known from Patent Document 1 is an improvement method of the foundation ground to be constructed before construction of the structure, in which the chemical solution material is dispersed and infiltrated into the soil that is the foundation of the structure. Therefore, depending on the geology, it is necessary to inject a large amount of chemicals to consolidate and strengthen the soil. And this improved construction method is generally constructed before the construction of the structure, and there is a problem that the workability is impaired as a means for reinforcing and stabilizing the support ground of the building after construction. Therefore, there is a problem that a sufficient strengthening function is difficult to be exhibited, the cost is increased, and economic efficiency is impaired.

  In addition, in the chemical solution injection means in the structure restoration method known from Patent Documents 2 and 3, since the emphasis is on ensuring lifting force for the structure on the ground, it becomes multi-point injection, Since it is an operation to lift the foundation together, there is a problem that the injection amount of the chemical liquid material inevitably increases, and it is often unsuitable for performing general ground strengthening and improvement.

Japanese Patent No. 3418069 Japanese Patent No. 3126896 Japanese Patent No. 36553305

  The problem to be solved by the present invention is that the chemical solution is injected independently to the required base with respect to the support base of the existing structure, and the load is sequentially applied to the important points in the soil under the support base using the load of the structure. The purpose of the present invention is to improve the ground strength by forming a consolidated structure so as to be in equilibrium with the ground and increasing the local pressure density of the ground, so that the structure can be reasonably supported stably.

In order to achieve the above object, the ground improvement method of the present invention is:
During foundation under basic soil structure, the liquid injection rod inserted placed at the required position, construct a consolidated body liquid injector rod instantaneous formation of chemical materials by the intermittently press-fitted operation in the soil and evaporated to Wari裂by chemical material that is subsequent press-Homogeru portion of the consolidated body which is being solidified is injected earlier, is entering the chemical material around the soil of the consolidated body, Wari裂and / or infiltration Repeatedly, in the ground improvement method to form a consolidated structure by the chemical material and soil grains under the base independently, and to consolidate the foundation soil by this consolidated structure and strengthen the ground strength ,
The chemical solution injection rod installation position is set at a plurality of locations by sharing the position away from the load action center of the structure, with the diagonal end position of the base on the diagonal passing through the load action center at the time of injection as a fulcrum, It is characterized in that the injection operation is performed so that a loading load larger than the central acting load due to the base of the structure is applied to the chemical injection site .

The loading position of the chemical injection rod in the invention is urged to be larger than the load action center position on a line passing through the load action center of the structure with respect to the base formation projection surface of the structure on the ground. at a position biased in a direction, the solid fine granulated bodies are reclamation is provided at a plurality of locations at intervals that do not interfere with each other, it is preferable to allow the injection of sequential chemical materials by changing the liquid injection position. Therefore, when the base of the structure is a “solid base”, it is distributed to multiple sections according to the projected area of the base, and placed in each of the sections so that the load described above acts on the chemical material injection part. In addition, it is preferable to supply and inject the chemical liquid material to the chemical liquid injection rod at a required interval.

According to the ground improvement method of the present invention, the instantaneously setting chemical solution material is intermittently applied to the soil while being balanced with the uneven load caused by the load (loading load) of the structure corresponding to the base of the constructed structure. By injecting, a solidified structure is formed by combining the chemical liquid material and soil particles at a required position under the base, and a supporting force corresponding to the uneven load is obtained, and this operation is performed at a plurality of locations corresponding to the base. By carrying out in order, consolidation and strengthening of the balanced soil of the entire foundation ground can be achieved, and a stable ground can be formed with a ground strength corresponding to the structure.

  In addition, it is a construction method that increases the earth strength by injecting chemicals only to the important points in the soil under the foundation corresponding to the base of the structure, thereby increasing the earth strength, so it does not use excessive chemicals and has an economic effect. Can also be improved.

FIG. 1 schematically shows an embodiment of the ground improvement method according to the present invention. FIG. 2 is a diagram schematically showing an enlarged form of one form during a chemical solution injection operation. FIG. 3 is a plan view showing an embodiment in which a chemical liquid material injection position is set by dividing into a plurality of bases of a rectangular structure, (a) showing the distributed injection section, and (b) to (g). Diagram showing the mode of each injection section

  Next, an embodiment of the ground improvement method according to the present invention will be described with reference to the drawings.

  The ground improvement method of the present invention basically reinforces the ground 2 (soil) on the lower side of the base 1 of the already constructed structure, and the load of the structure acting on the ground 2 as its basic operation. In a state where the chemical material injection position is assigned to multiple positions away from the center of action (eccentric) and the loading load at the time of injection is increased, a quick-setting chemical liquid material is injected and fixed in the soil. A bonded structure is created, and this operation is sequentially performed at a plurality of locations to obtain a supporting force and at the same time increase the pressure density of the ground.

  In this embodiment, as illustrated in FIG. 3 (a), the division section is determined by dividing into a plurality of distributions corresponding to the projection surface shape of the base 1 of the structure (in this embodiment, the division section is divided into six sections). Set the chemical material injection position at the center position of each section, perform the injection operation by intermittently injecting the chemical liquid material for each section in the selected order, and then move this operation to other sections in order. To do. FIG. 1 shows an embodiment in which a chemical liquid material is injected into a required location under the base of the structure.

  At this time, if the base 1 of the structure is a so-called “solid foundation”, depending on its planar shape or the like, if it is square as shown in FIG. The chemical material injection position is set in at least one place in the middle part. Of course, a chemical liquid material injection position is also arranged on the inner side surrounded by the periphery as necessary. These chemical liquid material injection positions are preferably distributed so that the consolidated structure 20 formed by the injected chemical liquid material is independently formed. The inner injection position is selected according to the shape of the projection surface of the base 1 of the structure.

  As the chemical solution injection rod 3 to be used, a known double tube structure rod is used. The liquid injection rods 3 are supplied with the liquid A and the liquid B from the liquid supply tanks 11 and 12 of the chemical liquid supply unit 10 through the on-off valves 14 and 14 'by the high-pressure pumps 13 and 13'. Supply pipes 15 and 16 (for example, hoses) are piped. When the chemical injection rods 3 are provided at a plurality of locations from the high-pressure pumps 13 and 13 ', a switching valve (not shown) is provided in the piping to each chemical injection rod 3 to control the switching valve / open / close valve. The supply of the chemical solution can be automatically switched by operating by means (not shown).

  On the other hand, the chemical liquid material to be injected by the chemical liquid injection rod 3 is a quick-setting chemical liquid material. For example, as the A liquid, sulfuric acid (75%), sodium silicate (No. 5) and water are approximately 6:34. : 200 liters at a ratio of 60, and B liquid is 200 liters of calcium aluminosilicate, slaked lime, cement, sodium bicarbonate and water at a ratio of 10: 10: 75: 3: remaining amount. A grout having a gelation time of about 1 to 3 sec is used by mixing and injecting the liquid and the liquid B at a ratio of 1: 1. In addition, about the component of this chemical | medical agent, the thing of the component suitable for maintaining the bond strength while changing gelation time is not employ | adopted as the said component.

  Such a chemical liquid material is sequentially applied to each chemical liquid injection rod 3 at a discharge rate of about 10 to 20 liters / min at high pressure by the high pressure pumps 13 and 13 ′ of the liquid A and the liquid B of the chemical liquid supply unit 10. Or supply selectively. As for the injection pressure, when the soil is a sandy layer and the injection speed is relatively high, the injection can be performed at a low pressure. Moreover, since the resistance at the time of injection increases in clay soil, it is necessary to increase the injection pressure.

  When the chemical solution is injected at the required pressure, the A solution and the B solution are mixed at the discharge port 3a of the chemical solution injection rod 3 and are injected into the soil. The injected and mixed chemical liquid materials (A liquid and B liquid) are ejected from the discharge port 3a of the chemical liquid injection rod 3 and kept in a liquid state within the range of the gelation time to freely flow and permeate and bond with the soil particles. First, the consolidated body 20a in the initial stage is formed. In the outer peripheral portion of the solidified body 20a formed in this way, it is injected first and entraps and accumulates earth and sand (soil grains) in the soil. However, since the solidified body 20a is in the process of developing strength, it is easily pulsated. A part of the subsequent chemical liquid material that splits and ejects from the split part 21 penetrates into the soil. The infiltrated chemical liquid material is mixed with the soil particles and solidified at the portion, and a new consolidated layer 20b is formed around the previously formed consolidated body 20a, and the consolidated body 20a is increased ( (See the enlarged illustration in FIG. 2). Since the chemical liquid material is intermittently injected from the chemical liquid injection rod 3 at a required interval, the chemical liquid injection rod 3 is press-fitted into the consolidated layer 20b expanded from the inside of the initial solidified body 20a to the surroundings, and further as described above. It cleaves around the formed consolidated layer and is also diffused into the surrounding soil.

In the chemical material injection position thus injected, first, the setting position of the division section away from the load action center position P of the structure, for example, the position A in FIG. 3B (hereinafter referred to as “first injection position”). The chemical solution injection rod 3 is inserted as shown in FIG. 1 through the base 1 of the structure, and the discharge port 3a is opened toward the lower soil of the base 1. The When the above-described chemical liquid material is supplied to the chemical liquid injection rod 3 and press-fitted into the soil, the chemical liquid material is dispersed and infiltrated around the discharge port 3 a of the chemical liquid injection rod 3. The consolidated structure 20 is formed by the bonding (condensation). At this time, the chemical liquid material is injected so that the applied load greatly acts on the required range of the chemical liquid material injection position. That is, the base 1 of the structure that covers the upper layer of the ground 2 is regarded as a loading board, and the load action center with one end Q (an end opposite to the chemical solution injection position (first injection position P ₁ )) as a support point. A ratio (L: L ′) between the distance L to P and the distance L ′ from the one end Q to the chemical injection position (first injection position P ₁ ) on a line (diagonal line) passing through the load acting center P, expanding the load sharing so that the mounting load is applied largely to the required range of the first injection position P _1. As a result, the pressure density with respect to the surrounding soil of the consolidated structure 20 to be created is further increased.

In the process of performing this injection operation, as schematically shown in FIG. 3B, the fulcrum Q of the base 1 in a free state with the formation of the solidified structure 20 by the chemical injection under the base 1. A load reaction force is generated on the (end) side, and a portion of soil corresponding to the end Q of the base 1 is consolidated and consolidated. In addition, in the lower part of the base between the part to be consolidated and the formation part of the consolidated structure 20, the load is radially directed to the intermediate part centering on the chemical solution injection position (first injection position P ₁ ). It is distributed and energized in a gradually decreasing manner (this manner is represented by hatching density). In addition, at the time of injection | pouring of this chemical | medical solution material, it carries out, measuring the level of the base | substrate 1 and maintaining an equilibrium state.

The splitting / penetration action varies depending on the geology of the ground where the work is performed. For example, when the ground is a sandy layer, the chemical liquid material that splits the homogel portion of the consolidated body 20a is the same as that of the split consolidated body 20a. penetrate into the surrounding soil condense involving the sand, by its behavior is intermittently repeated, the Katayuitai 20a is expanded reclamation. Moreover, when the ground geology is a clayey layer, since the injection resistance of the chemical liquid material is increased, the chemical liquid material is intended to split the homogel portion of the previously formed solidified body 20a and enter the surrounding soil. Energizes the injection pressure to the soil and pushes it to a balanced state, expanding and forming the consolidated body 20a, compressing the surrounding soil, and consolidating the soil as a result. Note that, depending on the geology, splitting and / or infiltration is repeated in parallel with respect to the behavior of the chemical liquid material, and the consolidated body 20a can be enlarged and formed.

In this way, the liquid injector operations in one place it is finished, then as shown in FIG. 3 (c), the liquid injection position (second injection position of the plane symmetrical positions from the first injection position P ₁ The chemical solution injection rod 3 is installed at P ₂ ), and the chemical solution material is injected as described above. By injection of the liquid medicine materials, as described above in the soil, the ends of the base 1 mounting load to liquid injection position P ₂ acts as a fulcrum Q _2, together with solid fine Zotai 20 to the position is Construction , compaction of soil around is made strong.

In the subsequent, as shown in FIG. 3 (d), the implanting the second injection position P ₂ and the diagonal positions (third injection position P ₃₎ by installing a liquid injection rod 3 in the same manner as described chemical material To do. In the chemical solution injection operation in this state, the fulcrum Q ′ of the base 1 serving as the loading board is positioned on the consolidated structure 20 previously formed. mounting load in the injection position P ₃ acting the way functions effectively, can enhance the reclamation effect of solid fine Zotai 20 by the liquid injector. Next, at the fourth injection position P ₄ (see FIG. 3 (e)), which is a symmetrical position, the chemical solution injection operation is performed in the same manner as the third injection position P _3, and the consolidated structure 20 is formed. Is done.

Thus after the solid fine Zotai 20 below the ground of the square corners of the base 1 is reclamation is FIG. 3 (f), the as shown in (g), the first injection position P ₁ and the third injection position _{P 3,} and performs liquid injection operation in the second injection position _{P 2} and the intermediate position between the fourth injection position _{P 4} (and the fifth injection position _{P 5} sixth injection position _{P 6).} In each of the fifth and sixth injection positions P ₅ and P ₆ , the opposite side of the base 1 on a line passing through the load acting center position P of the structure and the fifth or sixth injection positions P ₅ and P _6. parts mounting load will act as a fulcrum Q "a. in this state, already Construction of solid fine Zotai 20 in the first injection position P ₁ to the fourth injection position P ₄ is performed, each solid fine granulation Since the surrounding soil of the body 20 is consolidated and strengthened, when the chemical injection operation is performed as described above on the soil that is in a lower pressure dense state than the strengthened portion generated between the consolidated structures 20, The consolidated structure 20 is created within a range until the corresponding soil is balanced, and the surrounding soil is consolidated.

  When the consolidated structure 20 is formed in the lower soil of the base 1 in this way, the surrounding soil is united with the consolidated structure 20 by these consolidated structures 20, or the soil is pushed away to the surroundings. As a result, the soil in the peripheral portion is consolidated, and the consolidated structure 20 becomes a support structure, and the ground strength of the ground is enhanced by the functions of both. Therefore, by distributing the chemical liquid material injection locations to the required locations corresponding to the size of the base 1 of the structure, the chemical liquid material injection operation with the respective chemical liquid injection rods 3 is sequentially performed at desirable intervals. Then, the foundation ground of the target structure can be strengthened and stabilized.

  In the above-described embodiment, the case of using a quick-setting chemical liquid material as the chemical liquid material to be injected has been described. However, the quick-setting chemical liquid material and the slow-setting chemical liquid material are used by switching according to the situation in the field. Is also possible. Examples of the slow-binding chemical liquid material include 200 liters of 30:70 ratio of sodium silicate (No. 5) and water as the A liquid, and calcium aluminosilicate, slaked lime, cement, and sodium bicarbonate as the B liquid. A grout having a gelation time of 30 to 60 sec, in which a mixture of 10: 10: 75: 3: the remaining amount is 200 liters and the mixture is injected at a ratio of 1: 1, is used. Of course, the component of the chemical liquid material is not limited to the above, and a component suitable for changing the gelation time and maintaining the bonding strength can be employed.

  The ground improvement method of the present invention is not limited to general buildings as structures, but also provides structural foundations for civil works such as embankment L-shaped retaining walls and foundations for construction waterways or box culverts. It can be applied as a stabilizing means for the supporting ground.

1 structure of the substrate 2 Ground 3 liquid injector rod 3a discharge port 10 the chemical solution supply unit 13, 13 'high-pressure pump 20 solid fine Zotai 20a Katayuitai 20b Katayuiso 21 percent cleft partial load operating center P ₁ ~ P-structure P ₆ chemical injection position

Claims (3)

During foundation under basic soil structure, the liquid injection rod inserted placed at the required position, construct a consolidated body liquid injector rod instantaneous formation of chemical materials by the intermittently press-fitted operation in the soil and evaporated to Wari裂by chemical material that is subsequent press-Homogeru portion of the consolidated body which is being solidified is injected earlier, is entering the chemical material around the soil of the consolidated body, Wari裂and / or infiltration Repeatedly, in the ground improvement method to form a consolidated structure by the chemical material and soil grains under the base independently, and to consolidate the foundation soil by this consolidated structure and strengthen the ground strength ,
The chemical solution injection rod installation position is set at a plurality of locations by sharing the position away from the load action center of the structure, with the diagonal end position of the base on the diagonal passing through the load action center at the time of injection as a fulcrum, A ground improvement method characterized by performing an injection operation so that an applied load larger than an action center load by the base of the structure is applied to a chemical injection site . The installation position of the chemical solution injection rod is biased in a direction in which the loaded load is urged larger than the load action center position on a line passing through the load action center of the structure with respect to the base formation projection surface of the structure on the ground. in position, soil improvement according to claim 1, wherein the solid fine granulated bodies are reclamation is provided at a plurality of locations at intervals that do not interfere with each other, to allow injection of sequential chemical materials by changing the liquid injection position Construction method. When the base of the structure is a “solid base”, the position of the chemical injection rod is allocated to a plurality of sections according to the projected area of the base, and is arranged for each of the divided sections. The ground improvement construction method according to claim 1 or 2, wherein the ground material improvement part is operated by supplying the chemical liquid material to the chemical liquid injection rod at a predetermined interval and injecting the chemical liquid material.

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