JP6710807B2 - Method of manufacturing improved body - Google Patents

Description

The present invention discharges a solidifying agent while excavating the ground in order to increase the strength of the ground supporting the building or the like when constructing a building or a structure on the ground such as soft ground or low strength, and the solidifying agent The present invention relates to ground improvement work in which an excavated earth and sand are mixed and stirred to provide an improved body in which they are solidified.

Conventionally, in the ground improvement work, a ground improvement device having an excavation shaft and an excavation blade at least near the tip thereof is used, and the tip (lower end) of the excavation shaft is rotated while the excavation shaft is rotated with the ground (ground surface) as the excavation start surface. While pushing into the ground and lowering it, the ground is excavated in a columnar shape, and while the solidifying agent (solidifying agent) in the form of slurry such as cement milk is discharged from the vicinity of its tip, for example, Mixing and stirring are performed, and the excavating shaft is moved up and down appropriately or a suitable number of times to mix and stir the solidifying agent and the excavated soil over a predetermined depth, and then the excavated soil is solidified (solidified) into a columnar shape (cylinder). It is known that a columnar improved body is formed in the ground by binding (Japanese Patent Application Laid-Open No. 8-120665). That is, in such ground improvement work, in order to obtain the necessary ground strength according to the weight of the building or structure to be constructed on the ground, etc., with a predetermined diameter and a predetermined height in the ground ( A depth improvement body (columnar solidified body) is provided. In such ground improvement work, the simplest pile type consisting of one improved body, a plurality of improved bodies in plan view, with appropriate intervals, or in plan view, part of which is in contact (circle contact) Further, an improved body according to the design is provided such as a wall type in which parts are partially overlapped with each other, for example, a wall type in which they are arranged in series, or a block type in which groups are arranged vertically and horizontally in a grid pattern.

In such ground improvement work, the above-mentioned one improved body or a group of a plurality of improved bodies (hereinafter, also simply referred to as an improved body) formed in the ground (under the ground), etc. (hereinafter, floor) (Also called attachment surface), the foundation that supports the columns and walls of buildings and structures is formed. On the other hand, the flooring surface, which is the upper end of such an improved body, may be set at a position where it can be dug down to a predetermined depth below the ground. FIG. 4 is an explanatory view schematically showing the improvement body 201 provided in the ground 100. The improvement body 201 is formed at a predetermined height (H2) in the ground 100, and is the upper end of the floor attachment. A state in which the surface 205 is below the ground surface 101 by a predetermined dimension (H1) and the foundation K is formed on the flooring surface 205 is shown. Note that FIG. 4 illustrates a block-type improved body (9 improved body group) composed of the 3×3 improved bodies 201 in a plan view (FIG. 4-B) and arranged in a grid pattern vertically and horizontally.

The formation of the improved body 201 with the formation (finishing, formation) of the flooring surface 205 has been conventionally performed as follows. That is, conventionally, as shown in FIG. 5A, from the ground 101 to the ground 100, a predetermined position (up to a depth H (H1+H2) that becomes a lower end surface (improved bottom) 202 of the improved body (columnar body) ( In the plan view (9 locations), the above-described ground improvement device 300 performs the above-described excavation and mixing and stirring to form a temporary improved body (hereinafter referred to as an intermediate improved body). On the other hand, in the step of forming the intermediate improvement body, as shown in FIG. 5B, the upper end 203 thereof is raised above the ground 101 before excavation due to the excavation of the ground and the mixing and stirring of the soil. Therefore, the intermediate improvement body 200 including the upper end portion as well is subjected to the finishing work thereafter so that the upper end portion reaches the level of the flooring surface 205 located below the ground 101 by a predetermined (design) depth (H1). Are removed and drilled down. As a result, the improved body 201 is formed as shown in FIG. 5-C. As a result, the improvement body 201 is provided in the ground 100 with a predetermined height (H2) with the floor forming surface 205 for foundation formation, which is a predetermined depth (H1) below the ground 101, as the upper end. On the flooring surface 205 which is the upper end surface of the improved body 201 thus finished, flooring work for forming a foundation K as shown in FIG. 4 is then performed, and a building or structure is formed on the foundation K. The body is built.

In the formation of the improved body by the soil improvement work, as shown above, due to the excavation of the ground for forming the intermediate improved body 200 before being finished as the improved body and the mixing and stirring of the earth and sand, as shown in FIG. As shown, the upper end 203 of the intermediate improvement body 200 rises above the ground 101 at the excavation site. That is, in such ground improvement work, since the solidifying agent is added in addition to the mixing and stirring of the sand and sand, the bulk of the intermediate improvement body (columnar body) 200 mainly composed of the sand and sand increases during the formation process. Therefore, the upper part of the intermediate improvement body 200 is raised so as to be higher than the ground 101 before construction. Therefore, as shown in FIG. 5C, in order to form the improvement body 201 in which the floor forming surface 205 for forming the foundation, which is the upper end, is located below the ground 101 by a predetermined depth, In addition to the earth and sand in the area that is raised above, it is necessary to remove the earth and sand in the area above the intermediate improvement body 200 below the ground 101, that is, the earth and sand located above the designed flooring surface 205.

JP-A-8-120665

On the other hand, the improved body formed in the ground improvement work as described above, by the solidifying action by the solidifying agent in the form of slurry such as cement milk, because the mixed sand is solidified, the improved body and In the finishing work that forms the flooring surface that forms the upper end, the earth and sand that is the target earth and sand to be removed in the intermediate improved body (earth and sand to be removed), which is raised above the ground and is raised, is also dug down from the ground. The soil in the area to be treated also contains lumps in a solidified state by a solidifying agent such as cement milk, or they are mixed, so they should be treated as industrial waste (hereinafter also referred to as industrial waste). .. For this reason, in the above-mentioned finishing work, not only the work for removing and excavating (digging up) the soil to be removed, but also because it is industrial waste, it is necessary to crush and process the ground. There was a problem that the cost of construction (manufacturing of the improved body) was increased.

The present invention has been made to solve such a problem, and an industrial waste is disposed in a ground improvement work in which an improvement body whose upper end serving as a flooring surface is located at a predetermined depth below the ground is provided in the ground. It is an object of the present invention to provide a new and useful method for producing an improved body, which is effective in reducing the production cost of the improved body by reducing the generation of the soil to be removed as an object and the treatment cost thereof.

In the invention according to claim 1, the solidifying agent is discharged while excavating the ground, and the solidifying agent and the excavated earth and sand are mixed and stirred to form an intermediate improved body which is solidified in the ground. Of the improved body, the removal target site above the design flooring surface is removed, and the improved body is provided in the ground such that the upper end of the flooring surface is located at a predetermined depth below the ground. In the manufacturing method of the improved body,
Before excavating the ground, in the area where it will not be deeper than the floor depth of the design, the ground is dug down at the planned construction site to provide a recess,
After forming the recessed portion, when forming the intermediate improved body, the excavation is started with the bottom surface of the recessed portion as an excavation start surface, the solidifying agent is discharged while excavating, and the solidifying agent and the excavated earth and sand are mixed. In the recess, the upper end of the intermediate improver, which is agitated and solidified in the ground, is located above the position where the upper surface of the intermediate improver is the designed flooring surface, and moreover, before the recess is dug down. Formed so that it is located below the ground,
After the formation of the intermediate improved body, the part to be removed of the intermediate improved body, which is above the designed flooring surface, is removed, and the upper end of the flooring surface is at a predetermined depth below the ground. It is characterized in that the improved body located at is provided in the ground .

The invention according to claim 2 is the same as that according to claim 1, in which a recess is provided by digging down the ground at a planned construction site in a range that does not become deeper than the designed flooring surface depth,
It is a method for manufacturing an improved body, characterized in that a recess is formed by digging down the ground at a planned site to a designed flooring depth.

As another invention (hereinafter, referred to as “reference invention”) different from the inventions described in claims 1 and 2, a solidifying agent is discharged while excavating the ground, and the solidifying agent and the excavated earth and sand are mixed and stirred. Form an intermediate improved body that is solidified in the ground, and remove the part to be removed of the intermediate improved body that is above the design flooring surface so that the upper end that becomes the flooring surface is In the method for manufacturing the improved body, the improved body located at a predetermined depth below the ground is provided in the ground.
Before the ground is excavated, the depth is deeper than the designed flooring surface depth, and due to the increase in the bulk of the intermediate improver caused in the step of forming the intermediate improver, the upper end of the intermediate improver is In the depth range above the flooring surface, the ground is dug down at the planned construction site to provide a recess, and when forming the intermediate improvement body, excavation is started with the bottom surface of the recess as the excavation start surface. There are things that are characterized by that.

The present invention according to claim 1, wherein an improved body having a predetermined height whose upper end is a designed flooring surface for forming a foundation, which is a predetermined depth below the ground, is produced in the ground. Instead of starting the excavation from the ground (ground surface) before the start of construction to form the intermediate improvement body, before the main work, that is, before excavating the ground, ) The ground is dug down within a range that does not become deeper, and a recess is provided in the planned construction site. When the intermediate improvement body is formed, the bottom of the recess is used as an excavation start surface to start excavation. For this reason, in the intermediate improvement body, by the finishing work for removing the removal target portion above the position (height position) that becomes the designed floor attachment surface, the upper end that becomes the floor attachment surface has a predetermined depth from the ground. When an improved body located below is installed in the ground, it is subject to industrial waste treatment including the upper end of the intermediate improved body to be removed, as compared to the case where the intermediate improved body was formed by excavating from the ground as in the past. The amount of earth and sand (earth and sand for industrial waste treatment) can be reduced.

That is, in the method for manufacturing the improved body of the present invention, before starting the excavation of the ground, the recess is provided, and the bottom surface thereof serves as the excavation start surface, so that the ground is used as the excavation start surface without providing such a recess. As compared with the case where the intermediate improved body is formed, the amount of the earth and sand subject to industrial waste treatment to be removed can be reduced even if the bulk is increased. Therefore, since the processing cost can be reduced, the manufacturing cost (construction cost) of the improved body can be reduced. Since the earth and sand generated in the step of forming the recess is not industrial waste, it can be treated as usual residual soil, or can be used for backfilling the foundation in the subsequent step.

In the formation of the concave portion, it is preferable that the bottom surface of the concave portion is close to the designed position (height) of the flooring surface in order to reduce the amount of industrial waste to be treated. As described above, it is more preferable to dig into the recessed portion until the bottom surface reaches the designed flooring surface depth. Even if it is dug down to the floor depth of the design, after forming the intermediate improved body by excavating the bottom surface as the excavation start surface, due to the increase in the above-described bulk that occurs in the step of forming the intermediate improved body, The upper end of the intermediate improvement body does not become lower than the designed flooring surface, and in this way it is possible to reliably reduce the amount of earth and sand to be removed, and also to set the depth of the recess when digging. This is because there are no mistakes and the construction can be carried out smoothly and quickly.

Note that, as in the above-mentioned “reference invention” , due to the increase in the bulk of the intermediate improved body, which is deeper than the designed flooring surface depth before the ground is excavated and occurs in the step of forming the intermediate improved body. Then, the upper end of the intermediate improved body is dug into the ground at a planned construction site to provide a recess in a depth range above the designed flooring surface, and in forming the intermediate improved body, By starting the excavation with the bottom surface of the concave portion as the excavation start surface, it is possible to more efficiently reduce the earth and sand to be removed in the finishing work after the intermediate improvement body is formed.

That is, in the case of providing the recess, even if the depth is deeper than the designed flooring surface depth, if the depth is within a certain range from the designed flooring surface Due to its increased bulk, the upper end of the intermediate improvement formed can be located above the designed flooring surface. Therefore, when the concave portion is provided as in the above-mentioned “reference invention” , the amount of the industrial waste processing target earth and sand to be removed in the finishing work can be reduced more efficiently than in the case of claim 2. Therefore, the cost can be greatly reduced. Further, according to this reference invention, the excavation start of the bottom surface of the recess is a drilling start surface, even begin discharging solidifying agent (on), when the bottom surface of the concave portion is shallower than the floor with surface depth of design Compared with the above, since the amount of the solidifying agent used can be reliably reduced, the use cost of the solidifying agent is not increased, and an improved product of high quality (high strength) can be obtained. It should be noted that the depth to which the depth of the floor surface to be designed is to be dug may be obtained and set as follows, for example.

First, a trial formation of the intermediate improved body (test drilling) is performed, and in the intermediate improved body after the formation, the growth rate α (where α>1) for increasing the volume, which is a certain rate of increase in bulk, is investigated. From the depth from the ground to the designed flooring surface (H1) and the designed underground height (H2) of the improved body to be formed with the flooring surface as the upper end, the depth of the recess recessed from the ground The height F is based on F≦(H1+H2)−H2/α, and in the range of deeper than (H1), the upper end of the intermediate improved body is It may be set so as to be surely located above the designed floor mounting surface.

That is, the numerical values (dimensions) of the design depth (H1) to the floor mounting surface and the design ground height (H2) of the improved body to be formed with the floor mounting surface as the upper end are (By design) On the other hand, in calculation, if this underground height (H2) is divided by this increase rate α, and the underground height (H3) corresponding to the numerical value obtained is formed as an intermediate improvement body as an excavation target, the increase in bulk results in Thus, an intermediate improved body having the same height as the designed underground height (H2) can be obtained. Here, the intermediate improved product having the same height as that of the improved product is obtained when the increase rate is α and the bulk is increased. Therefore, from the numerical value (H1+H2) obtained by adding the designed depth (H1) of the flooring surface to the designed underground height (H2) of the improved body, the calculated underground height (H1+H2) The depth of the numerical value obtained by subtracting (H3) is dug down as the depth of the recess, and the bottom surface thereof is used as the excavation start surface, and the depth of (H3) obtained as described above is excavated from the bottom surface. The intermediate improved body obtained by mixing and stirring is an intermediate improved body of the same height as the improved body of the underground height (H2) whose upper end is located at the designed floor depth (H1) in calculation. Becomes That is, when the recess is dug down at the depth (F1) obtained by the formula (H1+H2)-H2/α to form the intermediate improvement body, the sediment to be removed becomes 0 (none) in the calculation. From the above, the digging depth F is in a range deeper than (H1), and is based on the numerical value obtained from F1=(H1+H2)−H2/α, in consideration of variations in increase in bulk, etc. The upper limit of (F1) may be set appropriately smaller than (F1) so that it is surely positioned above the designed flooring surface.

It is a typical longitudinal cross-sectional view of the construction ground explaining the process of the embodiment which materialized the manufacturing method of the improvement body of Claim 1, Comprising: A is the state which formed the recessed part, B is an intermediate improvement body. The formed state, C is a schematic vertical cross-sectional view illustrating a state in which the sand (industrial waste) in a portion above the designed flooring surface of the intermediate improved body is removed to form the improved body. It is a typical longitudinal cross-sectional view of the construction ground explaining the process of the example of embodiment which materialized the manufacturing method of the improvement body of Claim 2, A is the state which formed the recessed part, B is an intermediate improvement body. The formed state, C is a schematic vertical cross-sectional view illustrating a state in which the sand (industrial waste) in a portion above the designed flooring surface of the intermediate improved body is removed to form the improved body. It is a typical longitudinal section of construction ground explaining the process of the example of an embodiment which materialized the manufacturing method of the improvement object of "reference invention." A is a state where a crevice was formed, B is an intermediate improvement object. FIG. 3C is a schematic vertical cross-sectional view for explaining a state in which the soil is formed, C is an improved body by removing earth and sand (industrial waste) in a portion of the intermediate improved body above the designed flooring surface. It is a schematic diagram explaining the state which installed the foundation to the improvement body provided in the ground, and the flooring surface which is the upper end by the conventional manufacturing method of a improvement body, A is a schematic longitudinal cross-sectional view, B Is a schematic plan view. FIG. 5 is a schematic vertical cross-sectional view illustrating a process of providing the improved body of FIG. 4, where A is the depth (H1) from the ground to the designed flooring surface before construction (construction plan) and the flooring Schematic vertical cross-sectional view for explaining the ground height (H2) of the improved body to be formed below the surface, B is excavated from the ground downward to a depth (H) of (H1)+(H2) Is a schematic vertical cross-sectional view of a state in which the intermediate improved body is formed, and C is a state in which the sand and sand (industrial waste) in a portion of the intermediate improved body above the designed flooring surface is removed to form the improved body. The typical longitudinal cross-sectional view explaining.

An example of an embodiment embodying the method for manufacturing the improved body of claim 1 will be described with reference to FIG. However, in this example, when the same improvement body 201 as shown in FIG. 4 is formed in the ground 100, a predetermined depth (H1) from the ground (reference ground) 101, for example, 1.2 m below the ground, It is assumed that the improved body 201 having a predetermined height (H2) (for example, 4.0 m) is formed in the ground 100 with the designed flooring surface 205 for foundation formation set as above as the upper end. Further, the improved body 201 is a columnar one having a diameter of 1 m and a circular cross section, and is constructed in a block form in a contacting circle state, in total, 9 places, which are three places at a pitch of 1 m vertically and horizontally in plan view. (See FIG. 4-B). In addition, also in the following other embodiments, the ground is improved under the same conditions.

In such ground improvement, as a step of forming a recess before the main construction (before excavation of the ground), as shown in FIG. 1-A, deeper than the depth (H1) of the designed flooring surface 205. The depth (F) of the range that does not become, for example, the depth from the ground 101 is 1.0 m, and the ground 101 is dug down in the range of 3 m square in plan view, and the recess 120 is provided at the planned construction site. The bottom surface 123 of the recess 120 is appropriately leveled and flattened, and the next step of the main work (excavation, mixing and stirring) is performed. The rate of increase in bulk when forming an intermediate improvement in this ground improvement work is expected to be, for example, 15%. In addition, including the following description, numerical values such as the increase rate of the bulk, the designed depth (H1) of the flooring surface 205, the digging depth of the recess 120, and the mathematical formulas based on these are used in the formation of the intermediate improvement body. It is described only for the purpose of facilitating understanding of the increase in the bulk and the height of the earth and sand to be removed, and the unit is m (meter), but it is omitted as appropriate.

After providing the recesses 120 as described above, a suitable ground improvement apparatus 300 having, for example, an excavation shaft and an excavation blade near at least its tip as shown in FIG. Using the bottom surface 123 of the recess 120 as an excavation start surface, to the improved bottom (lower end surface) 202 which is the designed lower end of the improved body 201 to be formed, that is, from the bottom surface 123 of the recess 120 with a depth F of 1 m. Below 4.2 m (H1+H2-F), while excavating the excavation shaft in a column shape by rotating the excavation shaft, the solidification agent in the form of a slurry is discharged from the tip of the excavation shaft into the soil to solidify the solidification agent and excavated soil. Mix and stir. In this excavation process, the excavation shaft is appropriately moved up and down, the mixture is stirred, and then the apparatus 300 is pulled up. This is carried out at the above 9 places.

As the time elapses after the implementation, the excavated soil (mixed agitated earth and sand with the solidifying agent) excavated in a columnar shape and mixed and agitated is solidified, so that as shown in FIG. The intermediate improvement body (group) 200 is formed in which the lower end surface 202 is located at a predetermined depth (H1+H2) from the ground 101. The intermediate improved body 200 thus formed has an increase in its volume caused by mixing and stirring the excavated soil and the solidifying agent in the forming step, that is, in this example, the increase rate of the bulk is 15%. Due to the increase, the height (underground height) to the improved bottom (lower end surface) 202, which is the designed lower end of the intermediate improved body 200, is 4.2×1.15 from the calculation, 4 It will be 0.83m. Thereby, the upper end 203 of the intermediate improvement body 200 rises from the excavation start surface by 0.63 m from 4.83-4.2, from 1-0.63 below the ground 101, at a level of 0.37 m (height). Position). On the other hand, in this example, the flooring surface 205 is 1.2 m below the ground 101. Therefore, the height (H5) of the removal target earth and sand above the floor-mounting surface 205 level from the upper end 203 of the intermediate improvement body 200 toward the bottom (H5) is 1.2-0.37, which is 0. It is a part of 83m.

Thus, in this example, in order to obtain the improved body 201 shown in FIG. 1-C in which the flooring surface 205 is located 1.2 m below the ground from the intermediate improved body 200, as shown in FIG. 1-B. However, it is sufficient to remove the earth and sand containing the solidifying agent at the height portion of 0.83 m, which is the height (H5) portion including the upper end portion 203 of the intermediate improvement body 200, as the removal target. As a result, in the present example, the amount of industrial waste processing amount, which is the earth and sand containing the solidifying agent to be removed when the concave portion 120 is not provided, can be reliably reduced by the amount of providing the concave portion 120. Incidentally, in the case of forming the improved body 201 shown in FIG. 1-C in which the floor attachment surface 205 is located 1.2 m below the ground without providing the recessed portion 120 as in the conventional case, the ground is excavated as a start surface. As a result, an intermediate improved body is formed with the design improved bottom as the lower end. Therefore, the intermediate improved body has a calculated height of (1.2+4)×1.15=5.98 m due to an increase in bulk. Therefore, from 5.98-5.2, the earth and sand containing 0.78 m of the solidifying agent will rise on the ground. Of course, in reality, this is not the case because the rising sand flows around, but it is the case where there is no such flow. As a result, conventionally, in addition to the removal of such rising soil (sand containing a solidifying agent), the soil containing the solidifying agent of 1.2 m, which is the depth (H1) from the ground to the designed flooring surface. That is, assuming that there is no flow to the surroundings, it is necessary to remove the height of 1.98 m from 0.78+1.2 as the removal target. On the other hand, in this example, since the height of 0.83 m should be removed as the removal target, the amount of industrial waste that is the removal target soil can be greatly reduced compared to the conventional case.

Next, an example of an embodiment embodying the method for manufacturing an improved body according to claim 2 will be described with reference to FIG. 2. However, there is no essential difference in the work content (process) from the previous example, and there is a difference. Is only the following points. That is, in the step of forming the recessed portion 120 in the previous example, the bottom surface (excavation start surface) 123 of the recessed portion 120 has a depth (1.0 m) that is not deeper than the designed flooring surface 205 (H1) and the ground 101. While the concave portion 120 is provided by digging in, the bottom surface 123 of the concave portion 120 is located at the depth F ((H1)=1.2 m) in the design, that is, F=H1. The only difference is that the ground surface 101 is dug down to provide the recess 120. Therefore, in FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The same applies to the next embodiment. In this example, it is clear that the amount of industrial waste can be further reduced by increasing the digging depth as compared with the previous example.

That is, even in this example as described above, although the bulk is increased in the step of forming the intermediate improved body, it is located above the designed flooring surface 205 by the amount that the bottom surface 123 of the recess 120 is lowered as compared with the previous example. The height H5 of the part including the upper end 203 of the intermediate improvement body 200 can be reduced (see FIGS. 2-A and B). Therefore, in obtaining the improved body 201, the amount of the earth and sand to be industrially waste-treated that includes the solidifying agent of the height H5 portion including the upper end 203 portion of the intermediate improved body 200 to be removed can be reduced as compared with the previous example (FIG. 2-B, (See C). By the way, if this is shown by a numerical value, the intermediate improved body 200 formed in the present example has an improved bottom (lower bottom) which is the designed lower end of the intermediate improved body 200 due to the increase in the bulk that occurs in the forming process. The height of the ground up to the end surface) 202 is 4.6 m from 4×1.15, and the upper end 203 of the intermediate improvement body 200 is from 5.2-4.6 to a level of 0.6 m below the ground 101. Becomes On the other hand, since the flooring surface 205 is 1.2 m below the ground 101, the industrial waste sand (height H5) to be removed in the intermediate improvement body 200 is 0.6 m from 1.2-0.6, It can be further reduced from 0.83 m in the previous example.

Now, an example of an embodiment embodying the method for manufacturing the improved body of the reference invention will be described with reference to FIG. In this example, as shown in FIG. 3-A, the bottom surface (excavation start surface) 123 of the recess 120 in the recess forming step is deeper than the designed flooring surface 205 depth (H1) and the intermediate improved body. Due to the increase in the bulk that occurs in the forming step of the intermediate improver, the upper end 203 of the intermediate improver 200 formed in the forming step of the intermediate improver has a depth that is expected to be located above the designed flooring surface 205. The ground surface 101 is dug down within the range to provide the recess 120. Then, in the step of forming the intermediate improved body, the bottom surface 123 is used as the excavation start surface, and the same drilling, mixing and stirring are performed as described above to form the intermediate improved body 200 as shown in FIG. 3-B. . As a result, even in the intermediate improvement body 200, a portion having the height H5 to be removed is formed at the upper end portion thereof, which is above the designed flooring surface 205 level due to the increase in the bulk. The height is smaller than that in each of the above examples. As a result, also in this example as described above, after the formation of the intermediate improvement body 200, the earth and sand to be removed (the portion at the height H5) is removed, so that the upper end has the floor-attached surface 205 as shown in FIG. Although the improved body 201 that makes up the above is obtained, since the height H5 is low, the industrial waste treatment amount can be further reduced from the above examples.

The depth F of the recessed portion from the ground is based on F≦(H1+H2)−H2/α, as described above, and in a range deeper than (H1), in consideration of variations in bulk increase, It suffices to set the upper end of the intermediate improvement body to be surely positioned above the designed flooring surface due to the increase in the bulk. That is, when the recess is dug down at the depth (F1) obtained by the formula (H1+H2)-H2/α to form the intermediate improvement body, the sediment to be removed becomes 0 (none) in the calculation. Therefore, the digging depth F is in a range deeper than (H1), based on the numerical value obtained from F1=(H1+H2)−H2/α, in consideration of variations in increase in bulk, etc. The upper end may be set appropriately smaller than F1 so that it is surely located above the designed flooring surface. Note that the deeper the digging depth F of the recessed portion, the smaller the amount of earth and sand to be removed (the portion having the height H5) can be reduced, but specifically, it may be set as follows.

For example, a test intermediate improvement is formed (test drilling), and the rate of increase in the bulk of the intermediate improvement after the formation is investigated, and the increase rate α of the volume which is recognized to be surely increased (where α>1 ). This increase rate α is obtained from the rate of increase of the excavation depth (height) in the improved cylinder of the same diameter. The rate of increase in bulk of 15% exemplified in each of the above-mentioned examples is certain even if the variation in increase in bulk is taken into consideration, and in the formation of the intermediate improved body, the intermediate improved body has the same increase ratio (α=1.15). Is formed, the digging depth (F1) of the recess 120 where the upper end 203 of the intermediate improvement body 200 is at the same position (height) as the designed flooring surface 205 is F1=(H1+H2)-(H2 )/Α, in the above example, F1=(1.2+4)-4/1.15≈1.72. Therefore, the recess 120 may be dug within a range of 1.2 m to 1.7 m in depth from the ground. For example, assuming that the recess 120 is dug at a depth F from the ground 101 of 1.5 m, the distance from the ground 101 to the lower end surface (improved bottom) 202 of the improvement body 201 is 5.2 m. The excavation depth from the bottom surface 123 to the bottom is calculated from 5.2-1.5 to 3.7 m, and the height of the intermediate improvement body formed in that case is the lower end surface (improved bottom) 202. From above to 3.7×1.15=4.255. On the other hand, since the height (H2) from the improved bottom 202 of the improved body 201 is 4 m, the upper end 203 of the intermediate improved body 200 is located only 0.255 m above the designed flooring surface 205, Since this is the earth and sand to be removed in the production of the improved body, the earth and sand to be removed can be greatly reduced compared to the above examples. In this example, it is clear that the closer the depth of the recess 120 to the bottom surface 123 is to 1.7 m, the greater the reduction of the sand to be removed.

As described above, in this example, the recess 120 is dug deeper than the depth (H1) from the ground 101 to the flooring surface 205 of the designed foundation, and the bottom surface 123 is excavated as the excavation start surface to perform the intermediate improvement body 200. Although the upper end 205 of the intermediate improvement body 200 to be formed is positioned above the floor surface 205 of the design foundation without being positioned below the floor surface 205 of the design foundation due to the increased bulk, Since the improved body having the desired height H2 with the flooring surface 205 as the upper end can be obtained, and the industrial waste to be removed can be reduced more reliably than the above-mentioned examples, the manufacturing cost of the improved body can be greatly reduced. ..

As is clear from the above description, according to the method for manufacturing an improved body of the present invention, in the ground improvement work in which the improved body located below the predetermined depth from the ground is provided in the ground, the conventional method is used. Compared with the above, since it is possible to surely reduce the generation of the sand to be removed that becomes industrial waste, it is possible to reduce the manufacturing cost of the improved body. Further, the improved body to be manufactured is not limited to the block type in which the planar view as in the above example and the grid arrangement are arranged in the vertical and horizontal directions, and is a pile type consisting of one simple improved body, a plurality of improved bodies. In plan view, with appropriate spacing, or in plan view, manufacture of various types of improved bodies such as a wall type that is a series arrangement of partially contacting (circulating) or partially overlapping arrangements Widely applicable to.

100 Ground 101 Ground 120 Recess 123 Bottom of Recess (Excavation Start Surface)
200 Intermediate Improvement Body 201 Improvement Body 203 Upper End 205 of Intermediate Improvement Body 300 Flooring Surface 300 Ground Improvement Device H1 Designed Flooring Surface Depth

Claims (2)

The solidifying agent is discharged while excavating the ground, and the solidifying agent and the excavated earth and sand are mixed and stirred to form an intermediate improved body which is solidified in the ground. By removing the removal target site above the position to be the attachment surface, the upper end to be the floor attachment surface, to provide an improved body located a predetermined depth below the ground in the ground, in the method of manufacturing an improved body,
Before excavating the ground, make a recess by digging down the ground in the planned construction site within a range that does not become deeper than the designed floor depth,
After forming the recess, in forming the intermediate improved body, the bottom of the recess is used as an excavation start surface to start excavation, and the solidifying agent is discharged while excavating to mix the solidifying agent with the excavated earth and sand. In the recess, the upper end of the intermediate improver, which is agitated and solidified in the ground, is located above the position where the upper surface of the intermediate improver is the designed flooring surface, and moreover, before the recess is dug down. Formed so that it is located below the ground,
After the formation of the intermediate improved body, the part to be removed of the intermediate improved body, which is above the designed flooring surface, is removed, and the upper end of the flooring surface is at a predetermined depth below the ground. A method for producing an improved body, characterized in that the improved body located in the ground is provided in the ground . In claim 1, instead of digging the ground in the planned construction site to provide a recess within a range that does not become deeper than the designed flooring depth,
A method for manufacturing an improved body, characterized in that a recess is formed by digging down the ground at a planned construction site to a designed flooring depth.

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