JP2007177447A - Removal method for existing underground structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a removal method for an existing underground structure, which enables an underground structure as a removal object to be demolished/removed under a stable behavior, without being associated with complicated construction management, on a small construction site, by using inexpensive materials and equipment, without the need for the installation of large-scale or special equipment and the like. <P>SOLUTION: After a peripheral friction reducing layer 10a is formed between the underground structure 2a and ground, a self-hardening fluid 12a is press-fitted into a section between the batholith 2c and the ground by using a boring machine 7d, so that a solidified layer 12b with a thickness HQ can be formed and so that the underground structure 2a can be pushed upward. After that, the self-hardening fluid 12a is hardened so that the attitude and behavior of the underground structure 2a can be stabilized, and an upper section of the underground structure 2a is demolished from the ground depending on the amount (lift amount) HL of the motion of pushing the underground structure 2a. The above steps are repeated a plurality times, so that the underground structure 2a can be sequentially demolished and removed in order from the upper section to the lower one. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for removing an existing underground structure that pushes up and removes a structure existing underground.

  The dismantling / removal work of underground structures installed in the ground such as foundation structures and container structures has a problem that it takes both cost and time compared to the work of structures existing on the ground. In addition, the dismantling / removal work of such an underground structure has a problem that the workability is extremely poor because the degree of freedom of the work space is limited.

  10 (A) to 10 (C) are cross-sectional views showing a typical example of a conventional method for removing an underground structure. Conventionally, as a method of removing an existing underground structure, there is a method of pulling out the structure from the ground. This technology is applicable to columnar foundations such as piles that can be easily pulled out because of the small size of the structure. However, container structures and bridges and other heavy-duty structures constructed for the purpose of utilizing space. The foundation structure built to support an object inevitably increases the scale of the structure, so it is extremely difficult to remove it from the ground.

  Therefore, at present, such a large underground structure is being removed by a method as shown in FIGS. The method shown in FIG. 10 (A) is a method of excavating the surrounding area of the underground structure 2a from the ground surface 1a so that the ground surface around the underground structure 2a intended for removal becomes the slope 1c. After the side wall 2b of the underground structure 2a is completely exposed and the bottom plate 2c of the underground structure is placed on the excavation surface 1b, dismantling and removal are performed, and after the underground structure 2a is further removed, the excavated soil is removed. It is a method of backfilling.

  Further, in the method shown in FIG. 10B, a retaining wall is temporarily installed with a steel sheet pile 3 or the like so as to surround the underground structure 2a, and the space between the steel sheet pile 3 and the side wall 2b of the underground structure 2a is excavated. By doing so, the underground structure 2a is exposed, and the underground structure 2a is dismantled and removed. Furthermore, the method shown in FIG. 10C aims to improve work efficiency by chemically treating the dismantling process in FIG. 10B with blasting and an expanding agent. For example, when dismantling by blasting, the steel sheet pile 3 is temporarily installed so as to surround the underground structure 2a, and the crushing agent 4 is embedded in the side wall 2b and the bottom board 2c of the underground structure 2a. Disassemble the object 2a. In such a method, since an excavation process becomes unnecessary, work efficiency can be improved. In such a method, since the dismantling process can be shortened particularly in a large structure, the working efficiency is improved.

  On the other hand, conventionally, as a method for removing small foundation piles, etc., a method has been proposed in which a double-structure casing is built around the pile length on the outer periphery of the foundation pile, and the inner pipe and foundation pile of this casing are pulled out together. (For example, refer to Patent Document 1). In addition, after building the casing around the foundation pile to a position deeper than its bottom, high pressure water is injected from the upper end to the lower end of the drilling hole formed in the foundation pile, and this high pressure water causes There has also been proposed a method in which a foundation pile is lifted and pulled out by buoyancy (see, for example, Patent Document 2). Furthermore, as a method of lifting the foundation pile from the ground, besides the method of using water, a method of installing an inflatable bag body below the foundation pile and press-fitting the consolidated material into the bag body has been proposed. (For example, refer to Patent Document 3).

JP 2003-64680 A JP 2004-131923 A Japanese Patent Laid-Open No. 9-158235

  However, the removal method shown in FIG. 9 (A) requires a vast construction site and has a problem that it is difficult to apply in urban areas because it has a great influence on other underground objects. There is a point. Further, the removal method shown in FIG. 9 (B) has a problem that the scale of construction of the retaining wall becomes large, so that the burden of temporary material costs including support work is large. Furthermore, the removal method shown in FIG. 9 (C) requires a retaining wall, it is necessary to observe the influence of explosive pressure on other underground buried objects, and the generated dust, etc. There are problems such as the need to take environmental measures.

  Therefore, it is expected that the method of pulling out large underground structures from the ground will be applied to the method of dismantling and removing large underground structures as well as small foundation piles. The point that the size of the working machine required for ground equipment can be easily increased, the point that appropriate foundation work is required for the installation of these machines, and the point that the cost increase is inevitable. There are many problems that are difficult to solve in practice.

  For example, applying the methods described in Patent Documents 1 to 3 described above to a relatively large structure means that the capacity and number of jacks for pulling out, the casing that grows large, and the labor required to install these temporary devices, etc. Considering the above, it is not realistic, and it is not suitable for work types that require reduction of construction costs such as removal work.

  The present invention has been devised in view of the above-mentioned problems, does not require the installation of large-scale or special equipment, and does not involve complicated construction management at a low construction site by inexpensive materials and equipment. Furthermore, it aims at providing the removal method of the existing underground structure which can dismantle and remove the underground structure to be removed under stable behavior.

  In order to solve the above-described problems and achieve the object, the present invention is configured as follows.

  In the method for removing an existing underground structure according to the present invention, a self-hardening fluid is press-fitted between the bottom of the existing underground structure and the ground located below the existing underground structure, and the existing underground structure is moved upward. In accordance with the amount of pushing of the existing underground structure, and the step of stabilizing the posture and behavior of the existing underground structure by curing the self-hardening fluid. And disassembling the upper part from the ground.

  In this method of removing the existing underground structure, the step of controlling the amount of pushing of the existing underground structure by adjusting the amount of press-fitting of the self-hardening fluid to push the existing underground structure, the existing underground structure The step of stabilizing and the step of dismantling the existing underground structure can be repeated in this order, and the existing underground structure can be dismantled in multiple steps.

  In addition, before the step of pushing the existing underground structure, a peripheral friction reducing material that reduces frictional resistance generated between the existing underground structure and the ground may be injected.

  Further, before injecting the peripheral surface friction reducing material, water is injected between the side wall of the existing underground structure and the ground, and the frictional resistance generated between the outer surface of the side wall and the ground surface is temporarily increased. It can also be reduced. At that time, water may be injected between the bottom and the ground of the existing underground structure to temporarily reduce the frictional resistance generated between the outer surface of the bottom and the ground.

  According to the present invention, the self-hardening fluid is injected below the underground structure to push the underground structure upward, and the upper part of the underground structure is dismantled and removed after the self-hardening fluid is hardened. No need for installation of scale or special equipment, and dismantling / removing the underground structure to be removed under stable behavior without complicated construction management at low construction sites with inexpensive materials and equipment. Can do.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings, taking as an example the case of dismantling and removing a relatively large underground structure. FIG. 1 is a flowchart showing a method for removing an existing underground structure according to this embodiment. As shown in FIG. 1, in the method for removing an existing underground structure of the present embodiment, first, as a preparation stage, a hollow portion (hereinafter referred to as a middle wall) is formed in the underground structure, and load water is contained therein. Is stored (step S1), and the friction generated between the outer surface of the underground structure and the ground surface is temporarily reduced (step S2). Next, the bottom plate of the underground structure is drilled, and an injection pipe for injecting the friction reducing material and the self-hardening fluid is installed (step S3). And after injecting a friction reducing material between the outer surface of the underground structure and the ground surface from the injection pipe (step S4), a self-hardening fluid is injected into the lower part of the underground structure from the injection pipe. The underground structure is pushed upward (step S5). Next, after the injected self-hardening fluid is hardened, the portion pushed up to the ground of the underground structure is dismantled (step S6). Subsequently, the self-hardening fluid press-fitting process in step S5 and the dismantling process in step S6 are repeatedly performed (step S7), and after all the dismantling / removal of the underground structure is completed, the ground is leveled (step S8). Hereinafter, each process mentioned above is demonstrated in detail.

Step S1: Middle drainage (preparation)
FIG. 2 is a cross-sectional view illustrating a middle drainage step (step S1) in the method for removing an existing underground structure according to an embodiment of the present invention. As shown in FIG. 2, the underground structure 2a is not only constructed for the purpose of a container such as a basement, but it is constructed as a foundation. Instead, the intermediate collar 2d is formed. When the underground structure 2a is a container, the middle rod 2d is of course hollow. However, when the underground structure 2a is used as a foundation, a load up to the same level as the water level of the groundwater 5b is loaded inside. Many structures are designed to be filled with water 5a. Therefore, in the method for removing the existing underground structure of the present embodiment, as a preparation process for removal, the drainage pump 6a installed on the ground surface 1a and the drainage pipe 6b connected to the drainage pump 6a The load water 5a stored in 2d is drained. Thereby, in the subsequent processes, work from the inside of the intermediate roof 2d can be performed, and the entire weight of the underground structure 2a can be reduced.

Step S2: Reduction of peripheral friction (preparation)
FIG. 3 is a cross-sectional view showing a peripheral friction reducing step (step S2) in the method for removing an existing underground structure according to the embodiment of the present invention. As shown in FIG. 3, in this peripheral surface friction reducing step, the frictional force of the peripheral surface in contact with the ground surface in the underground structure 2a is temporarily reduced, and preparation for injecting the friction reducing material in step S4 is performed. Arrange.

  Specifically, a water storage tank 7e in which water 7g is placed on the ground surface 1a is installed, and one end of the water conduit 7f is connected to the water storage tank 7e through a valve 8. Furthermore, an injection pipe 7b having a jet nozzle 7c attached to the tip is connected to the other end of the water conduit 7f via an injection pump 7a capable of generating high pressure. Then, the valve 8 is opened, the water 7g in the water storage tank 7e is pumped up by the injection pump 7a, and the water 7g is discharged from the jet nozzle 7c to the entire side wall 2b of the underground structure 2a via the water conduit 7f and the injection pipe 7b. Spray onto the required area of the outer surface or part of it. Thereby, the surrounding surface friction of the outer surface of the side wall 2b and a ground surface can be reduced temporarily.

  In addition, when the adhesion between the ground and the underground structure 2a is extremely large, or when the work from the ground is inefficient or difficult due to the construction depth of the underground structure 2a, A drilling machine 7d may be installed in the middle rod 2d of the structure 2a, and this drilling machine 7d may be used as an injection machine to spray water from the inside of the underground structure 2a toward the ground. In this case, the operator 9 operates the drilling machine 7d to drill the side wall 2b of the underground structure 2a, and then continues to use the drilling machine 7d as an injection machine, and the jet attached to the tip of the injection pipe of the drilling machine 7d. Water 7g is sprayed from the nozzle 7c toward the ground.

  Furthermore, as shown in FIG. 3, when the work from the ground and the work from the inside of the underground structure 2a are used in combination, the efficiency and accuracy during construction can be further increased. Whether the peripheral friction reduction operation is performed from the ground or from the inside of the underground structure 2a can be selected as appropriate based on the scale of the underground structure 2a, the properties of the ground, the construction period, and the like.

  Further, in the case of the underground structure 2a having a large cross-sectional scale, it may be better to perform the friction reduction work similarly between the outer surface of the bottom plate 2c and the ground surface. In that case, for example, the bottom plate 2c is drilled in a direction perpendicular to the surface thereof (not shown) by the drilling machine 7d shown in FIG. 3, and the water 7g is sprayed in the same manner as described above over a plurality of locations. Do. On the other hand, when working from the ground, the work can be effectively performed by changing the injection direction of the jet nozzle 7c protruding from the tip of the injection pipe 7b from a vertically downward direction to a horizontal direction in advance.

  And at the time of the completion | finish of the operation | work in this surrounding surface friction reduction process, a surrounding surface friction reduction layer is temporarily formed between the outer surface of the underground structure 2a, and a ground surface. Here, the reason for “temporarily” is that, in this process, the ground is stirred with 7 g of water by the above-described series of operations, and the surrounding of the underground structure 2 a is only in a high water content state, and is long-term. This is because the expectation of the friction reducing effect is poor.

Step S3: Injection Pipe Construction FIG. 4 is a cross-sectional view showing an injection pipe construction process (step S3) in the method for removing an existing underground structure according to the embodiment of the present invention. As an injection machine for injecting the friction reducing material and the self-hardening fluid between the underground structure and the ground, for example, a drilling machine 7d can be used. In that case, as shown in FIG. 4, the drilling machine 7d is installed on the bottom board 2c of the underground structure 2a, and the operator 9 makes the bottom board 2c perpendicular to the ground surface on which the structure 2a is installed. And the injection pipe of the drilling machine 7d is built in the bottom plate 2c. In step S2, when the peripheral friction reducing layer 10 is formed below the bottom 2c of the underground structure 2a, the drilling machine 7d and the injection pipe used at that time can be used as they are. The process can be omitted.

Step S4: Friction reducing material injection FIG. 5 is a cross-sectional view showing a friction reducing material injection step (step S4) in the method for removing an existing underground structure of the embodiment of the present invention. In the friction reducing material injecting step, as shown in FIG. 5, a step for stably extending the life of the peripheral surface friction reducing layer 10 formed in step S <b> 2 and increasing the strength and pushing up the underground structure 2 a upward. Step on.

  Specifically, first, as a ground facility, a pipe is connected to an adjustment tank (not shown) for adjusting the concentration of mud water 11a serving as a friction reducing material on the ground surface 1a, and the underground structure 2a contacts the adjustment tank. A mud storage tank 7h that contains mud water 11a adjusted to a concentration that does not collapse even when replaced with the ground to be installed is installed. And the mud storage tank 7h and the injection pipe of the drilling machine 7a built in the underground structure 2a in step S3 are pipe-connected by the injection pipe 7b. At that time, a valve 8 and an injection pump 7a capable of generating high pressure are disposed in the middle of the injection pipe 7b. The muddy water 11a used here refers to a non-self-hardening fluid such as bentonite muddy water, and functions as a friction reducing material (sliding material) between the surface of the underground structure 2a and the ground surface.

  Next, the valve 8 is opened, and the muddy water 11a is pumped toward the drilling machine 7d by the injection pump 7a. Thereby, the muddy water 11a is sent to the lower part of the bottom board 2c of the underground structure 2a via the injection pipe 7b and the injection machine 7d. Thereafter, the muddy water 11a that has been fed mud flows into the periphery of the side wall 2b from below the bottom plate 2c of the underground structure 2a, using the peripheral friction reduction layer 10 formed in step S2 as a water conduit, and further the underground structure 2a. It flows over the entire circumferential surface in contact with the ground. And finally, it flows out to the ground surface 1a in the form of excess mud water 11b. If the excess mud water 11b that has flowed out to the ground surface 1a is expected to be insufficient in the mud storage capacity, it is returned to the adjustment tank by installing a separate pump, etc., adjusted again to a predetermined concentration, and reused as the mud water 11a It can also be disposed of when unnecessary.

  When a series of operations in the above-described friction reducing material injecting step is completed, the peripheral friction reducing layer 10 formed in step S2 is replaced with a mud water 11a acting as a friction reducing material (peripheral friction reducing layer 10a). Thus, even when the mud is stopped, the effect of reducing the peripheral friction is prolonged and increased in strength.

  In FIGS. 4 and 5, the circumferential friction reduction layers 10 and 10 a are described so as to ensure a certain layer thickness, but this is due to document notation, and is described below. This is the same in the figure. The actual peripheral friction reduction layers 10 and 10a are muddy water films that are in close contact with the outer surfaces of the side wall 2b and the bottom plate 2c of the underground structure 2a and have a thickness of about 1 to several tens of millimeters. When the layer thickness (film thickness) of the peripheral friction reduction layers 10 and 10a is increased more than necessary, the lateral displacement of the underground structure 2a caused by the peripheral friction reduction layers 10 and 10a increases, and the underground structure 2a. Therefore, the thickness of the peripheral surface friction reducing layers 10 and 10a is stable and within the range in which the underground structure 2a can be pushed in the press-fitting process of the self-hardening fluid described later. It is desirable to make it as thin as possible.

Step S5: Self-hardening fluid press-fitting FIG. 6 is a sectional view showing a self-hardening fluid press-fitting step (step S5) in the method for removing an existing underground structure according to the embodiment of the present invention. As shown in FIG. 6, in the self-hardening fluid press-fitting step, the self-hardening fluid 12a is injected into the lower part of the peripheral friction reduction layer 10a formed in step S4, and the solidified layer 12b is formed, thereby forming an underground structure. Stabilize the posture and behavior of 2a.

  Specifically, first, a solidification material tank 7i for storing a self-hardening fluid 12a that acts as a solidification material is installed on the ground. And the solidification material tank 7i and the injection pipe of the drilling machine 7a built in the underground structure 2a in step S3 are pipe-connected by the injection pipe 7b. At this time, as shown in FIG. 6, the injection pipe 7b connected to the solidifying material tank 7i is connected to the injection pump 7a provided in the pipe of the mud storage tank 7h installed in step S4 via the valve 8. You can also. In that case, by operating the valve 8 and switching the piping system, the self-hardening fluid 12a is injected into the lower portion of the circumferential friction reduction layer 10a formed below the underground structure 2a. Although FIG. 6 shows a case where the piping system for injecting the muddy water 11a and the piping system for injecting the self-hardening fluid 12a are partially in common, the present invention is not limited to this. Of course, it is possible to construct a plurality of injection facilities as a whole by using these as completely independent single injection lines.

  Then, the self-hardening fluid 12a is pumped by the injection pump 7a and injected into the lowermost portion of the circumferential friction reduction layer 10a via the injection pipe 7b and the injection pipe of the injection machine 7d. At this time, it is desirable to inject the self-hardening fluid 12a at a low rate in order to proceed the injection operation without damaging the circumferential friction reduction layer 10a, which is a muddy water film, as much as possible. Further, as the self-hardening fluid 12a, a material having a specific gravity larger than that of the muddy water 11a forming the peripheral friction reduction layer 10a, such as soil mortar and fluidized soil, is used.

  As the self-hardening fluid 12a is injected by the above-described method, the friction reducing effect between the surface of the base plate 2c of the underground structure and the surface of the side wall 2b and the ground surface by the peripheral friction reducing layer 10a, and the injection of the self-hardening fluid 12a. Due to the generation of the pressing force, the underground structure 2a is gradually pushed upward vertically, and a solidified layer 12b is formed below the underground structure 2a. At this time, the muddy water 11a of the peripheral surface friction reducing layer 10a that forms a mud film on the outer peripheral surface of the underground structure 2a is also pushed at the same time and flows out from the ground surface 1a as surplus muddy water 11b. What is necessary is just to process by the method similar to a friction reduction material injection | pouring process (step S4). In addition, the operator 9 can further protect the circumferential friction reduction layer 10a by operating the injection tube of the injector 7d according to the injection amount of the self-hardening fluid 12a and sequentially stepping down.

  Next, when the underground structure 2a is pushed upward, that is, when the underground structure lift amount HL reaches a predetermined value, the injection of the self-hardening fluid 12a is stopped and the valve 8 is operated. The piping system is switched to the mud storage tank 7h in which the mud water 11a is accommodated. Then, the muddy water 11a pumps the self-hardening fluid 12a remaining in the injection pump 7a, the injection pipe of the punching machine (injection machine) 7d, and the injection pipe 7b disposed therebetween, and injects it into the solidified layer 12b. To do. Thereafter, by pulling up the injection pipe of the drilling machine (injector) 7d to the inside of the underground structure 2a, all of the self-hardening fluid 12a inside the mechanical equipment is discharged, and problems due to sticking or the like are avoided. In that case, it is more desirable to once remove the equipment from the underground structure 2a and clean the inside with water or the like. Further, after the injection of the self-hardening fluid 12a is completed, the muddy water 11a is injected again into the peripheral friction reduction layer 10a formed around the underground structure 2a, thereby improving the durability of the peripheral friction reduction layer 10a. It can be ensured more stably and safely.

  After a series of operations in the above-described self-hardening fluid injection process, when a predetermined time has elapsed, the solidified layer 12b develops sufficient strength as a supporting ground for the underground structure 2a, and the underground structure 2a is installed extremely stably. It becomes a state. At this time, the relationship between the lift amount of the underground structure 2a and the injection amount of the self-hardening fluid 12a is partly influenced by the ground around the underground structure 2a. Since the thickness (solidified layer thickness) HQ of the layer 12b becomes substantially equal, by controlling the injection amount of the self-hardening fluid 12a, the underground structure lift amount HL can also be managed at the same time. This leads to labor saving in terms of management.

  In addition, the self-hardening fluid 12a is preliminarily determined so that the strength of the solidified layer 12b after curing is equivalent to or higher than the strength of the surrounding ground, thereby suppressing ground collapse. Furthermore, since the shape and scale of the underground structure 2a are the main factors and the time required for the dismantling process to be described later is affected, it is necessary to consider the curing time as an element for determining the formulation of the self-hardening fluid 12a is there.

Step S6: Dismantling FIG. 7 is a cross-sectional view showing a dismantling step (step S6) in the method for removing an existing underground structure according to the embodiment of the present invention. In addition, in FIG. 7, illustration about the injection-related equipment mentioned above is omitted. As shown in FIG. 7, in the dismantling process, the side wall 2b of the underground structure 2a is dismantled and removed by the amount HL of the underground structure by the crusher 13 installed on the ground surface 1a on the ground. At this time, since the underground structure 2a is installed in an extremely stable state by the solidified layer 12b formed by injecting the self-hardening fluid 12a below the bottom plate 2c in step S5, the underground structure is formed on the ground. It is not necessary to install facilities such as a support for supporting 2a. As a result, the workability of a large heavy machine or the like frequently used in dismantling work can be remarkably improved, and effects such as improvement of safety and reduction of work man-hours can be obtained.

  Basically, the demolition shell that has been demolished and crushed will be transported and carried out each time. However, when the weight of the underground structure 2a is relatively light, the injection machine installed in the intermediate rod 2d. It is also possible to adopt a method in which the dismantled shells are accumulated inside the intermediate rod 2d after all the work is completed (protection) for 7d and piping facilities, etc., and all the work is completed. it can. In FIG. 7, the breaker type crusher 13 is shown as the equipment used for dismantling, but the present invention is not limited to this, and the dismantling equipment includes the shape of the underground structure 2 a and the working environment. In addition to the crusher 13, for example, a hydraulic split rocker, a blasting and wire sawing machine, or the like can be used.

Step S7: Repetitive Construction FIG. 8 is a cross-sectional view showing a repeated construction process (step S7) in the method for removing an existing underground structure according to an embodiment of the present invention. In the removal method of the existing underground structure of this embodiment, the process of forming the solidified layer 12b by injecting the self-hardening fluid 12a and pushing the underground structure 2a upward, and the ground surface of the underground structure 2a The process of disassembling the portion pushed up at a position higher than 1a, that is, a series of operations in steps S5 and S6 is repeated.

  Specifically, as shown in FIG. 8, first, after the disassembly work of the side wall 2b of the first underground structure 2a is completed, the self-hardening fluid 12a is placed on the solidified layer 12b formed first. The second solidified layer 12b is formed by pouring. Then, similarly to the first time, the underground structure 2a is pushed upward by the underground structure lift amount HL. Then, the crusher 13 dismantles and removes the pushed-up portion of the side wall 2b of the underground structure 2a. After the second dismantling operation is completed, the third self-hardening fluid 12a is injected and solidified, and the underground structure 2a is disassembled. In this way, the side wall 2b of the underground structure 2a is dismantled and removed at the final stage of the dismantling process by repeatedly performing the self-hardening fluid injection process of step S5 and the dismantling process of step S6. To do. Thus, a plurality of solidified layers 12b having a thickness of HQ are formed and stacked on the portion where the underground structure 2a has been installed.

Step S8: Leveling FIG. 9 is a cross-sectional view showing the final state of the solidified layer formation stage and the leveling condition at the completion of construction in the method for removing an existing underground structure according to the embodiment of the present invention. As shown in FIG. 9, in the leveling process, after the removal of the underground structure 2a is completed, the topsoil 1d is buried so that the portion where the underground structure 2a is installed is at the same height as the ground surface 1a. Return and level. After completion of the repeating step of step S7, a plurality of solidified layers 12b are laminated, and a solidified material finishing layer 12c having a thickness of ΣHQ integrated as a whole is created. When the use is clear, according to the purpose, for example, by reducing the thickness ΣHQ of the solidified material finishing layer 12c and increasing the amount of backfilling soil, the land can be delivered smoothly.

  As described above, the removal method of the existing underground structure of this embodiment does not depend on the method of pulling out from the upper part, and it is not necessary to install large equipment and equipment such as dedicated heavy machinery on the ground. Construction in a place where it is difficult to secure a construction site is possible. In addition, it is not necessary to pre-process underground facilities such as buried objects other than the target existing underground structures, and it is not necessary to temporarily install earth retaining walls with sheet piles, etc. Costs and temporary construction costs can be reduced. In addition, in the method for removing the existing underground structure of the present embodiment, construction can be performed without using special materials and expensive materials, so that not only reduction of construction cost but also procurement of materials and equipment is easy. Become. Further, in the process of moving (pushing) the existing underground structure upward, the lowermost surface of the structure is always supported, so it is safer than the construction method that supports the side or upper part of the underground structure 2a. In addition, it is excellent in terms of environmental conservation because it can work with low noise.

  Furthermore, in the method for removing an existing underground structure according to the present embodiment, it becomes possible to simultaneously perform the removal of the existing underground structure and the backfilling process of the ground after the removal, thereby reducing the number of steps. In addition to simplifying the construction management, the work environment can be maintained without requiring any special measures even if unexpected events such as construction interruption occur. Furthermore, foundations, containers, large-sized, small-sized, or special-shaped structures can be removed without depending on the type of existing underground structure, and the applicable range is wide. Due to the above effects, according to the method for removing an existing underground structure of the present embodiment, it is possible to remove the existing underground structure that is safer and wider in application range than the conventional technology.

  In addition, when sufficient ground for construction can be secured on the ground part, and the injection pressure of the injection pump 7a is less than the design, for example, a crane or the like is installed on the ground part, and the drawing from the upper part is used as an auxiliary. The underground structure 2a can be easily removed. As described above, the combined use of the above-described construction method and the pulling-out construction method makes it possible to correct the inclination of the underground structure 2a, so that it can be applied to the removal of existing underground structures that have subsided and / or inclined due to ground subsidence or the like. be able to.

  Further, in the present embodiment, it has been described that dismantling and removal can be performed without depending on the scale and shape of the existing underground structure. However, for example, embedded concrete is filled in the lowermost part of a frame such as a pneumatic caisson. In addition, when there is a concern about insufficient strength in the bonding state between the side walls of the structure or between the side wall and the bottom board, such as when the adhesive strength with the main body structure is expected to be reduced, and when the underground structure is built, the sheet pile If there is a lack of unity between the foundation structure or the foundation structure and the incidental structure of this structure, such as a property that leaves a temporary earth retaining wall, etc. Application of the present technology becomes more effective by using an existing structure such as anchoring each other to form an integral structure.

  In addition, what is necessary is just to implement the middle waste draining process (step S1) mentioned above, a surrounding surface, and a friction reduction process (step S2) as needed, and also the structure of the removal method of the existing underground structure of this embodiment. It is within the scope of the present invention to carry out design changes as appropriate.

It is a flowchart figure which shows the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the middle drainage process (step S1) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the surrounding surface friction reduction process (step S2) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the injection pipe erection process (step S3) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the friction reduction material injection | pouring process (step S4) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the self-hardening fluid injection | throwing-in process (step S5) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the dismantling process (step S6) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the repeated construction process (step S7) in the removal method of the existing underground structure of embodiment of this invention. It is sectional drawing which shows the final state of the solidification layer formation stage in the removal method of the existing underground structure of embodiment of this invention, and the leveling condition at the time of completion of construction. (A)-(C) are sectional drawings which show the typical example of the removal method of the conventional underground structure.

Explanation of symbols

1a Ground surface (ground surface)
1b Ground surface (excavated surface)
1c Ground surface (slope)
1d Topsoil 2a Underground structure 2b Underground structure (side wall)
2c Underground structure (bottom)
2d Medium 3 Steel sheet pile 4 Fracturing agent 5a Loaded water 5b Groundwater level 6a Drain pump 6b Drain pipe 7a Injection pump 7b Injection pipe 7c Jet nozzle 7d Punching machine (injection machine)
7e Water storage tank 7f Water transfer pipe 7g Water 7h Mud storage tank 7i Solidified material tank 8 Valve 9 Worker 10, 10a Circumferential friction reducing layer 11a Mud water 11b Excess mud water 12a Self-hardening fluid 12b Solidified layer 12c Solidified material finishing layer 13 L Underground structure lift amount HQ solidified material layer thickness ΣHQ solidified material finishing layer thickness

Claims (5)

A step of press-fitting a self-hardening fluid between the bottom of the existing underground structure and the ground located below the existing underground structure to push the existing underground structure upward;
Curing the self-hardening fluid to stabilize the posture and behavior of the existing underground structure;
A step of dismantling the upper part of the existing underground structure from the ground according to the amount of pushing of the existing underground structure.   The step of controlling the amount of pushing of the existing underground structure by adjusting the amount of press-fitting of the self-hardening fluid, the step of pushing the existing underground structure, the step of stabilizing the existing underground structure, and the existing underground structure The method for removing an existing underground structure according to claim 1, wherein the steps of dismantling the object are repeated in this order to disassemble the existing underground structure in a plurality of times.   Before the step of pushing the existing underground structure, a peripheral friction reducing material for reducing frictional resistance generated between the existing underground structure and the ground is injected. Item 3. A method for removing an existing underground structure according to item 1 or 2.   Before injecting the peripheral surface friction reducing material, water is injected between the side wall and the ground of the existing underground structure to temporarily reduce the frictional resistance generated between the outer surface of the side wall and the ground surface. The removal method of the existing underground structure of Claim 3 characterized by the above-mentioned.   Further, before injecting the peripheral surface friction reducing material, water is also injected between the bottom and the ground of the existing underground structure, and the frictional resistance generated between the outer surface of the bottom and the ground is temporarily increased. The method for removing an existing underground structure according to claim 4, wherein the existing underground structure is removed.

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