Method for measuring compaction characteristics

Abstract

To further correctly evaluate quality of a structure.SOLUTION: A compaction property measuring method which measures a compaction property of soil material mixture 20 manufactured by mixing unwashed excavated soil materials, cement and water includes: a storing step of storing mixed soil material mixture 20 in a container 22; a primary compaction step of compacting the soil material mixture 20 stored in the container 22 within one hour after manufacturing of the soil material mixture 20; a secondary compaction step of compacting the soil material mixture 20 stored in the container 22 after elapse of predetermined lapse time which is one hour or longer after manufacturing of the soil material mixture 20; and a property measuring step of measuring a compaction property of the soil material mixture 20 compacted in the container 22. The compaction energy imparted to the soil material mixture 20 in the secondary compaction step is larger than the compaction energy imparted to the soil material mixture 20 in the primary compaction step.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The present invention relates to a compaction characteristic measurement method for measuring the compaction characteristics of a soil material mixture.

Background Art

[0002] Patent Document 1 discloses a CSG construction method in which cement and water are added to and mixed with in-situ generated materials (excavated soil materials), which are then transported to the construction site, spread evenly with a bulldozer, and compacted with a vibrating roller to construct a structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a CSG construction method such as the invention described in Patent Document 1, it may take a relatively long time from the production of CSG to its compaction. If the time until compaction is long, the compaction characteristics of CSG, such as the degree of compaction, may deteriorate due to the progress of cement coagulation. Since the length of the time until CSG is compacted varies depending on the location where CSG is spread evenly, it is difficult to accurately evaluate the quality of the entire structure only by grasping the compaction characteristics of CSG after a specific time has elapsed since production.

[0005] An object of the present invention is to more accurately evaluate the quality of a structure.

Means for Solving the Problems

[0006] The present invention relates to a compaction characteristics measurement method for measuring the compaction characteristics of a soil material mixture produced by mixing at least unwashed excavated soil material, cement, and water, comprising: a storage step of placing the mixed soil material mixture in a container; a primary compaction step of compacting the soil material mixture placed in the container within one hour after the production of the soil material mixture; a secondary compaction step of compacting the soil material mixture placed in the container after a predetermined elapsed time of one hour or more has elapsed after the production of the soil material mixture; and a characteristics measurement step of measuring the compaction characteristics of the compacted soil material mixture in the container, wherein the compaction energy applied to the soil material mixture in the secondary compaction step is greater than the compaction energy applied to the soil material mixture in the primary compaction step.

[0007] Furthermore, the present invention relates to a method for measuring the compaction characteristics of a soil material mixture produced by mixing excavated soil material, in accordance with JIS A 1204 "Method for Testing Particle Size of Soil", in which the mass fraction of particles passing through a sieve with a nominal size of 0.15 mm exceeds 3%, cement, and water, comprising: a storage step of storing the mixed soil material mixture in a container; a primary compaction step of compacting the soil material mixture stored in the container within 1 hour after the production of the soil material mixture; a secondary compaction step of compacting the soil material mixture stored in the container after a predetermined elapsed time of 1 hour or more has elapsed since the production of the soil material mixture; and a characteristic measurement step of measuring the compaction characteristics of the compacted soil material mixture in the container, wherein the compaction energy applied to the soil material mixture in the secondary compaction step is greater than the compaction energy applied to the soil material mixture in the primary compaction step.

[0008] Furthermore, the present invention relates to a compaction characteristics measurement method for measuring the compaction characteristics of a soil material mixture produced by mixing unwashed excavated soil material, cement, and water, comprising: a spreading step of spreading the mixed soil material mixture; a compaction step of compacting the spread soil material mixture after a predetermined elapsed time of at least one hour has elapsed since the production of the soil material mixture; and a characteristics measurement step of measuring the compaction characteristics of the compacted soil material mixture, wherein the compaction energy applied to the soil material mixture in the spreading step is smaller than the compaction energy applied to the soil material mixture in the compaction step.

[0009] Furthermore, the present invention relates to a method for measuring the compaction characteristics of a soil material mixture produced by mixing excavated soil material, in accordance with JIS A 1204 "Method for Testing Particle Size of Soil", in which the mass fraction of material passing through a sieve with a nominal size of 0.15 mm exceeds 3%, cement, and water, comprising: a spreading step of spreading the mixed soil material mixture; a compaction step of compacting the spread soil material mixture after a predetermined elapsed time of at least one hour has elapsed since the production of the soil material mixture; and a characteristics measurement step of measuring the compaction characteristics of the compacted soil material mixture, wherein the compaction energy applied to the soil material mixture in the spreading step is smaller than the compaction energy applied to the soil material mixture in the compaction step. [Effects of the Invention]

[0010] According to the present invention, the quality of structures can be evaluated more accurately. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-section of a trapezoidal CSG dam. [Figure 2] This is a front view of the trapezoidal CSG dam, seen from the upstream side. [Figure 3] This is a cross-sectional view showing the cross-section of the CSG layer that makes up the trapezoidal CSG dam. [Figure 4]This figure shows the steps for preparing a test specimen in chronological order in the method for measuring the compaction characteristics of a soil material mixture according to the first embodiment of the present invention. [Figure 5] This figure shows, in chronological order, the steps for preparing a test structure in a method for measuring the compaction characteristics of a soil material mixture according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0012] The following describes a method for measuring the compaction characteristics of a soil material mixture according to an embodiment of the present invention, with reference to the drawings. In this embodiment, the case in which the structure to be evaluated for quality by the compaction characteristics measurement method is a trapezoidal CSG dam 100 constructed by the CSG (Cemented Sand and Gravel) method will be described.

[0013] First, the trapezoidal CSG dam 100 will be described with reference to Figures 1 and 2. Figure 1 is a longitudinal section (upstream-downstream section) of the trapezoidal CSG dam 100, and Figure 2 is a front view of the trapezoidal CSG dam 100 as seen from the upstream side (a view of the trapezoidal CSG dam 100 as seen from the left side in Figure 1).

[0014] As shown in Figure 1, the trapezoidal CSG dam 100 is a trapezoidal dam with a roughly trapezoidal cross-section in the upstream-downstream direction. It is constructed by covering the surface of the dam body, which is made of trapezoidal CSG piled up, with protective concrete. Furthermore, as shown in Figure 2, the trapezoidal CSG dam 100 is anchored to bedrock 102 and 103 on its left and right sides, respectively. For the sake of explanation, the left-right direction shown in Figure 1, that is, the direction in which the river flows, will be referred to as the upstream-downstream direction of the trapezoidal CSG dam 100.

[0015] The CSG (Cement-Based Stabilizer) used for the dam body of the trapezoidal CSG Dam 100 is a soil material mixture (cement-based compound) produced by mixing water and cement with excavated soil materials (locally sourced materials) consisting of sand, gravel, and rock fragments readily available around the construction site. As aggregate, it contains coarse aggregate such as crushed stone and coarse gravel with a particle size of about 80 mm, which is larger than the maximum particle size (40 mm) of aggregates used in typical ready-mixed concrete. Although the excavated soil materials may be processed to remove oversized pieces or to crush them, classification, particle size adjustment, and washing are not generally performed. In other words, CSG, which uses excavated soil materials as its main raw material, can be continuously manufactured using simpler equipment than that used for manufacturing concrete, and the construction of the trapezoidal CSG Dam 100 does not require equipment such as aggregate manufacturing equipment that is necessary for the construction of typical concrete dams. Regarding cement, there are various types such as Portland cement, blended cement, and special cement, but Portland cement and blended cement (such as blast furnace cement and fly ash cement) are used for CSG and the CSG method. In particular, moderate-heat Portland cement, blast furnace cement (Type B), a mixture of Portland cement and fly ash, or a mixture of moderate-heat Portland cement and fly ash cement can be used.

[0016] The trapezoidal CSG dam 100 is constructed by stacking CSG layers 10, each equivalent to one lift, from bottom to top, formed by pouring CSG, which is a soil material mixture as described above. The height of each CSG layer 10, i.e., the lift height h, is approximately 75 cm to 100 cm.

[0017] Figures 1 and 2 show a simplified trapezoidal CSG dam 100 consisting of six CSG layers 10. The CSG layers 10 are formed with shorter lengths in the upstream and downstream directions as they are formed higher up. As a result, stepped sections are formed on the upstream and downstream sides of the trapezoidal CSG dam 100.

[0018] Next, with reference to Figure 3, the construction method for each CSG layer 10 will be explained. Figure 3 shows a cross-section of the CSG layer 10 under construction.

[0019] The CSG layer 10 is constructed by a so-called thin-layer spreading method that thinly and widely spreads the CSG. As shown in FIG. 3, it is constructed as a structure by curing a plurality of layers 11, 12, 13 formed by CSG overlapping in layers.

[0020] Specifically, first, the CSG is transported to the construction site by a transport machine such as a dump truck, conveyor, or crane, and the transported CSG is leveled and compacted by a leveling machine such as a bulldozer, thereby forming the bottommost first layer 11.

[0021] Subsequently, the CSG is transported onto the upper surface of the leveled first layer 11 by a transport machine, and the transported CSG is leveled and compacted by a leveling machine, thereby forming the intermediate second layer 12.

[0022] Furthermore, the CSG is transported onto the upper surface of the leveled second layer 12 by a transport machine, and the transported CSG is leveled and compacted by a leveling machine, thereby forming the uppermost third layer 13.

[0023] After the third layer 13 is formed, as shown in FIG. 3, the surface of the third layer 13 is rolled by a compaction machine (rolling machine) such as a vibrating roller 16, and the first layer 11, the second layer 12, and the third layer 13 are compacted. That is, at least the uppermost layer among the three layers 11, 12, 13 constituting the CSG layer 10 is leveled by a leveling machine and then rolled and compacted by a compaction machine. Note that the first layer 11 and the second layer 12 may also be leveled by a leveling machine and then rolled and compacted by a compaction machine in the same manner as the third layer 13.

[0024] The heights of each layer 11, 12, and 13 formed in this manner (the first height h1 being the height of the first layer 11, the second height h2 being the height of the second layer 12, and the third height h3 being the height of the third layer 13) are set to approximately 10 cm to 30 cm, respectively. However, the heights of each layer 11, 12, and 13 are not exactly the same, and differences arise depending on the leveling and compaction conditions.

[0025] By repeating this process and stacking the CSG layers 10 in layers from bottom to top, the trapezoidal CSG dam 100 is constructed as a structure.

[0026] In the CSG method described above, it can take a relatively long time (for example, up to 6 hours) from the time that the CSG (soil material mixture) is produced by adding and mixing cement and water to the excavated soil material (on-site source material) until compaction (rolling) is performed. If the time until compaction is long, the cement may set to some extent before compaction begins, which may reduce the compaction characteristics of the CSG, such as the degree of compaction. This reduction in compaction characteristics affects the density and strength of the structure, leading to a decrease in density and strength, and ultimately reducing the quality of the CSG as a structural element.

[0027] The time it takes for the CSG to be compacted varies depending on where the CSG is laid. For example, as mentioned above, if the CSG layer 10 consists of multiple layers, the bottommost first layer 11 will only be compacted together with the second and third layers 12 and 13 by a compaction machine (compactor) after the second and third layers 12 and 13 have been laid. Therefore, the time it takes for the first layer 11 to be compacted after it has been laid will be longer than the time it takes for the second and third layers 12 and 13 to be compacted. Similarly, the time it takes for the second layer 12 to be compacted after it has been laid will be longer than the time it takes for the third layer 13 to be compacted.

[0028] Thus, the length of time that CSG is left undisturbed between its spreading and the start of compaction varies depending on the location where the CSG is spread within the structure. In other words, the length of time from the time the CSG is manufactured, that is, the time when cement and water are mixed with the excavated soil material, to the time when compaction by compaction machinery (compactor) begins, varies depending on the location where the CSG is spread, for example, which of layers 11-13 the CSG is spread into.

[0029] The time elapsed between the manufacture of CSG and the start of compaction affects the structural quality of the CSG once it is compacted. Therefore, understanding the timing of compaction after a predetermined period of time has elapsed is crucial for maintaining and improving quality.

[0030] Therefore, in the soil material mixture compaction characteristics measurement method according to the embodiment of the present invention, the compaction characteristics of the soil material mixture can be understood by compacting the CSG, which is a soil material mixture used to construct a structure, under temporal and physical conditions that reflect actual construction, and measuring the compaction characteristics of the compacted soil material mixture.

[0031] <First Embodiment> The method for measuring the compaction characteristics of a soil material mixture (CSG) according to the first embodiment of the present invention will be described below with reference to Figure 4. In the method for measuring the compaction characteristics of a soil material mixture according to the first embodiment, a test specimen is prepared using CSG used in the construction of structures, and the compaction characteristics of the prepared test specimen are measured. Figures 4(A) to 4(C) are diagrams showing the process of preparing a test specimen whose compaction characteristics are measured in chronological order.

[0032] First, referring to Figure 4, we will explain the process for preparing the specimens in which the compaction characteristics are measured.

[0033] In preparing the test specimens, a soil material mixture 20 (CSG) is produced by mixing excavated soil material (on-site sourced material) with water and cement using a mixer such as a pot mixer (manufacturing process). The produced soil material mixture 20 is then stored in a cylindrical container 22 in the storage process shown in Figure 4(A).

[0034] The excavated soil material used in the production of the soil material mixture 20 is the same material used to construct structures, is unwashed, locally sourced material, and, in accordance with JIS A 1204:2009 "Soil Particle Size Test Method", the mass fraction of material passing through a sieve with a nominal size of 0.15 mm exceeds 3%, preferably exceeds 5%, of the total excavated soil material. Furthermore, the excavated soil material is adjusted to a maximum particle size (80 mm) or less by removing oversized particles as needed. Thus, since the soil material mixture 20 contained in the container 22 includes excavated soil material with a relatively large particle size of about 80 mm, the inner diameter of the container 22 is set to a size of at least three times the maximum particle size, preferably about 300 mm.

[0035] Next, in the primary compaction process shown in Figure 4(B), the soil material mixture 20 contained in the container 22 is compacted with a tamping rod (not shown), and then further compacted with an electric hammer 24 for a predetermined time, for example, 5 to 10 seconds. Note that the compaction of the soil material mixture 20 may be performed by a vibrating tamper instead of the electric hammer 24.

[0036] This initial compaction process is performed to replicate the state in actual construction where CSG, which is still relatively fluid, is compacted to some extent by leveling machinery such as bulldozers. For this reason, the initial compaction process is carried out to coincide with the timing of leveling in actual construction, for example, within one hour after the soil material mixture 20 is manufactured.

[0037] Furthermore, in the primary compaction process, the number of times the soil material mixture 20 is tamped with a tamping rod and the time spent compacting the soil material mixture 20 with the electric hammer 24 are predetermined so that the density of the soil material mixture 20 after the primary compaction process is completed is equivalent to the density of the CSG after it has been leveled by a leveling machine in actual construction.

[0038] Furthermore, the number of times the soil is tamped with the tamping rod and the time spent compacting with the electric hammer 24 may be set so that the energy of the impact applied to the soil material mixture 20 is equivalent to the compaction energy applied to the CSG by the leveling machine in actual construction.

[0039] Once the primary compaction process is completed, the secondary compaction process, as shown in Figure 4(C) and described later, is carried out. However, before the secondary compaction process is carried out, the soil material mixture 20 is left to stand for a predetermined period of time during the resting process.

[0040] The resting stage is performed to replicate the conditions in actual construction where CSG is left to rest after being spread by leveling machinery such as bulldozers, and before being compacted by compaction machinery (compaction machines) such as vibratory rollers.

[0041] In actual construction, the CSG is left unattended for a maximum of about 6 hours, whereas the time from the manufacture of the CSG to the completion of spreading is generally less than 1 hour, which is a shorter time compared to the unattended period. Therefore, in actual construction, the time the CSG is left unattended before being compacted by compaction machinery is approximately equal to the time from the manufacture of the CSG to the compaction machinery.

[0042] Furthermore, since the cement setting reaction begins at the time CSG is manufactured, that is, from the moment cement and water are mixed with the excavated soil material, it can be said that the change in the compaction characteristics of CSG over time begins from this point.

[0043] Furthermore, in actual construction, the amount of time the CSG is left undisturbed varies depending on the location where the CSG is spread, as mentioned above.

[0044] Taking these factors into consideration, in this embodiment, the time elapsed from the production of the soil material mixture 20 until the start of the secondary compaction process is set in advance for each container 22, with the time being equivalent to the time the CSG is left to stand after being spread in actual construction until it is compacted by a compaction machine. Furthermore, since the structure is constructed by the final compaction, the time until compaction is completed is closely related to the structural quality of the CSG.

[0045] This elapsed time is set to a different length for each container 22, specifically at intervals of 1 to 2 hours between 1 hour and 8 hours after the manufacture of the soil material mixture 20, so as to ensure that the time during which the CSG is left to stand during actual construction is included. The measurement of elapsed time begins in the manufacturing process of the soil material mixture 20, when the cement and water are mixed with the excavated soil material.

[0046] However, the elapsed time set is not limited to this; the elapsed time may be set to a time exceeding 8 hours after the manufacture of the soil material mixture 20, or the elapsed time may be set to a time that assumes the time when the CSG is left unattended is 0 hours, i.e., the time when the CSG is left unattended is 0 hours.

[0047] Alternatively, instead of using elapsed time, the time elapsed from the completion of the primary compaction process to the start of the secondary compaction process may be used as the time the CSG is left unattended during actual construction, and this time may be set as the unattended time for each container 22. In this case, the measurement of the unattended time begins at the time the primary compaction process is completed.

[0048] Once the resting process is complete, that is, once the predetermined elapsed time for each container 22 has elapsed, the soil material mixture 20 contained in the container 22 is compacted by the electric hammer 24 for a predetermined time, for example, 50 to 60 seconds, in the secondary compaction process shown in Figure 4(C). The time required for compaction in the secondary compaction process is at most about 90 to 120 seconds. Since the compaction time for secondary compaction is significantly longer than that of primary compaction, the compaction energy imparted to the soil material mixture 20 via the electric hammer 24 is greater. Therefore, it can be said that secondary compaction has a greater compaction load and is stronger than primary compaction. In other words, primary compaction is weaker than secondary compaction. Also, since the time required for compaction work is at most about 2 minutes, in the compaction process performed after a predetermined time of 1 hour or more has elapsed, the time when compaction starts can be said to be roughly the time when compaction is completed.

[0049] This secondary compaction process is performed to reproduce the state in which the CSG is compacted by compaction machinery (compaction machines) such as vibratory rollers during actual construction. Therefore, the time for compacting the soil material mixture 20 with the electric hammer 24 during the secondary compaction process is set in advance so that the density of the soil material mixture 20 after the secondary compaction process is equivalent to the density of the CSG after it has been compacted by compaction machinery during actual construction.

[0050] In addition, during the secondary compaction process, the time for compacting the soil material mixture 20 with the electric hammer 24 may be set such that the energy of the impact applied to the soil material mixture 20 is equivalent to the compaction energy that the compaction machine applies to the CSG in actual construction.

[0051] Furthermore, while the secondary compaction process assumes that the CSG is compacted by compaction machinery (compactors) such as vibratory rollers in actual construction, as described above, the primary compaction process assumes that the CSG is compacted as a result of being spread by leveling machinery such as bulldozers, as described above. However, in actual construction, the degree of compaction by leveling machinery is much smaller than that by compaction machinery such as vibratory rollers. For this reason, in order to simplify the specimen preparation process, the primary compaction process may be omitted, and only the secondary compaction process may be performed.

[0052] After the secondary compaction process is completed, the soil material mixture 20 in each container 22 is cured in a curing process under predetermined curing conditions for a predetermined period. After a sufficient curing period (for example, 2 to 3 days) has elapsed and the soil material mixture 20 has hardened to a certain extent, it is removed from the container 22 as a test specimen.

[0053] The cylindrical specimen removed from container 22 is then subjected to a subsequent property measurement process, in which its density is measured as the compaction property of the soil material mixture 20.

[0054] Specifically, the volume and weight of the specimen are measured, and the density is calculated from the measured volume and weight. If there is a risk of the specimen collapsing when measuring the volume, the density of the specimen is measured using an RI densimeter, which irradiates the specimen with gamma rays and calculates the density from the transmission attenuation rate.

[0055] The density is calculated for each specimen, that is, for each soil material mixture 20 that has been compacted in multiple containers 22, each with a different elapsed time. Therefore, it is possible to understand how the compaction characteristics of the soil material mixture 20 change depending on the elapsed time (1 hour to 6 hours).

[0056] Furthermore, as a measure of the compaction characteristics of the soil material mixture 20, the water content of the specimen and the compressive strength of the specimen may be measured in addition to, or instead of, the density of the specimen.

[0057] In this way, by understanding the compaction characteristics of the soil material mixture 20 according to the elapsed time, even in cases where the time the CSG is left to stand after being spread by a spreading machine and before being compacted by a compaction machine differs depending on the location where the CSG is spread, such as in a trapezoidal CSG dam 100, if the time left to stand at each location where the CSG is spread is recorded, it is possible to determine the compaction characteristics corresponding to the standing time from the results measured by the compaction characteristics measurement method described above. Therefore, even with relatively large structures, the quality of the entire structure can be accurately evaluated by clearly determining the compaction characteristics of each part of the structure.

[0058] Alternatively, instead of recording the time the CSG is left to stand, the time elapsed from the time the CSG is manufactured until it is compacted may be recorded for each location where the CSG is spread. In this case, the recorded elapsed time corresponds to the elapsed time set for each container 22, and the compaction characteristics corresponding to the recorded elapsed time can be determined from the results measured by the compaction characteristics measurement method described above. Therefore, even in this case, the compaction characteristics of each part of a relatively large structure become clear, and the overall quality of the structure can be accurately evaluated.

[0059] According to the first embodiment described above, the following effects and advantages are achieved.

[0060] In the above-described compaction characteristics measurement method, the compaction characteristics of the soil material mixture 20 are measured through the following steps: a storage step of placing the mixed soil material mixture 20 into a container 22; a compaction step of compacting the soil material mixture 20 placed in the container 22 after a predetermined elapsed time of 1 hour or more has elapsed since the manufacture of the soil material mixture 20; and a characteristics measurement step of measuring the compaction characteristics of the compacted soil material mixture 20 in the container 22.

[0061] By understanding the compaction characteristics of the soil material mixture 20 according to a predetermined elapsed time, even in cases where the time the CSG is left to be compacted differs depending on the location where it is spread, such as in a trapezoidal CSG dam 100, if the time the CSG is left to be spread is recorded for each location where it is spread, the compaction characteristics corresponding to the time the CSG is left to be spread can be determined from the results measured by the compaction characteristics measurement method described above. Therefore, even with relatively large structures, the quality of the entire structure can be accurately evaluated by clearly determining the compaction characteristics of each part of the structure.

[0062] Furthermore, in the compaction characteristics measurement method described above, the conditions for compacting the soil material mixture 20 contained in the container 22 are set to simulate the leveling and compaction processes in actual construction. By setting the conditions for compacting the soil material mixture 20 in a way that can reproduce the compaction state caused by leveling and compaction in actual construction, it becomes possible to grasp the compaction characteristics under conditions close to actual construction, and as a result, the compaction characteristics of the entire structure can be grasped with greater accuracy.

[0063] Furthermore, the following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configuration described in the first embodiment above, or to combine the configurations described in the following different modifications.

[0064] The soil material mixture 20 of the first embodiment described above may contain an admixture that has the effect of delaying the setting reaction of cement. The admixture is a so-called setting retarder such as "Frolic T (Frolic is a registered trademark)" (manufactured by Frolic Co., Ltd.), for example, one in which the difference in cement setting time according to JIS A 1147:2019 "Test method for concrete setting time" is approximately +95 minutes at the start time and approximately +100 minutes at the end time. The admixture should be such that the difference in cement setting time according to JIS A 1147:2019 "Test method for concrete setting time" is +0 minutes or more at the start time and +15 minutes or more at the end time.

[0065] Specifically, in the containment process, soil material mixtures 20 with different amounts of admixture added are contained in multiple containers 22 set to the same length of time, and in the characteristic measurement process, the compaction characteristics of the compacted soil material mixtures 20 are measured. By changing the amount of admixture added to the soil material mixture 20 in this way, it is possible to understand the effect of the admixture on the compaction characteristics.

[0066] Furthermore, by placing soil material mixtures 20 with the same amount of admixture added into multiple containers 22 set to different elapsed times, and measuring the compaction characteristics of the compacted soil material mixtures 20, it is possible to understand how the compaction characteristics of soil material mixtures 20 with added admixtures change with different elapsed times.

[0067] Furthermore, by comprehensively understanding the changes in the compaction characteristics of the soil material mixture 20 due to differences in elapsed time and the amount of admixture added, even if the amount of admixture added to the CSG differs in each part of the structure, if the amount of admixture added in each part and the time the CSG was left standing or the time elapsed from the time the CSG was manufactured until it was compacted are known, the corresponding compaction characteristics of the CSG can be determined from the results measured by the compaction characteristics measurement method described above.

[0068] <Second Embodiment> Next, with reference to Figure 5, a method for measuring the compaction characteristics of a soil material mixture (CSG) according to the second embodiment of the present invention will be described. In the method for measuring the compaction characteristics of a soil material mixture according to the second embodiment, the compaction characteristics of a test structure obtained by spreading and compacting a material equivalent to that used for the construction of a structure using the same equipment as that used in actual construction are measured. Figures 5(A) and 5(B) are diagrams showing the manufacturing process of the test structure whose compaction characteristics are measured in chronological order.

[0069] First, referring to Figure 5, we will explain the process of preparing the test structure whose compaction characteristics will be measured.

[0070] In preparing the test structure, a soil material mixture 20 (CSG) is produced by mixing excavated soil material (on-site sourced material) with water and cement using a mixer such as a pot mixer (manufacturing process). Then, in the spreading process, the produced soil material mixture 20 is spread in predetermined sections demarcated on the test yard, as shown in Figure 5(A).

[0071] The soil material mixture 20 is spread using a spreading machine such as a bulldozer 26, just as in actual construction. The soil material mixture 20 is spread and compacted to some extent by the spreading machine. The spreading process is carried out within one hour of the production of the soil material mixture 20, in accordance with the timing of spreading in actual construction. Although spreading with a spreading machine such as a bulldozer has a compaction effect, the compaction energy imparted to the soil material mixture 20 is small compared to compaction with a compaction machine (compactor) such as a vibratory roller, so it can be said to be a weak compaction.

[0072] Once the leveling process is complete, the compaction process described later is carried out. However, before the compaction process, the soil material mixture 20 is left to stand for a predetermined period of time during the resting process.

[0073] The resting stage is performed to replicate the conditions in actual construction where CSG is left to rest after being spread by leveling machinery such as bulldozers, and before being compacted by compaction machinery (compaction machines) such as vibratory rollers.

[0074] In actual construction, the CSG is left unattended for a maximum of about 6 hours, whereas the time from the manufacture of the CSG to the completion of spreading is generally less than 1 hour, which is a shorter time compared to the unattended period. Therefore, in actual construction, the time the CSG is left unattended before being compacted by compaction machinery is approximately equal to the time from the manufacture of the CSG to the compaction machinery.

[0075] Furthermore, since the cement setting reaction begins at the time CSG is manufactured, that is, from the moment cement and water are mixed with the excavated soil material, it can be said that the change in the compaction characteristics of CSG over time begins from this point.

[0076] Furthermore, in actual construction, the amount of time the CSG is left undisturbed varies depending on the location where the CSG is spread, as mentioned above.

[0077] Taking these factors into consideration, in this embodiment, the time elapsed from the time the soil material mixture 20 is manufactured until the compaction process by the compaction machine begins is set to correspond to the time the CSG is left unattended in actual construction, and this elapsed time is predetermined for each section where the soil material mixture 20 is spread. Since the time required for compaction work by a compaction machine (compactor) such as a vibratory roller is about 5 minutes, in the compaction process that is carried out after a predetermined time of 1 hour or more has elapsed, the time when compaction begins can be said to be approximately the time when compaction is completed.

[0078] This elapsed time is set to a different length for each section where the soil material mixture 20 is spread. Specifically, it is set at intervals of 1 to 2 hours between 1 hour and 8 hours after the manufacturing of the soil material mixture 20, so as to ensure that the time during which the CSG is left to stand during actual construction is included. The measurement of elapsed time begins in the manufacturing process of the soil material mixture 20, when the cement and water are mixed with the excavated soil material.

[0079] However, the elapsed time set is not limited to this; the elapsed time may be set to a time exceeding 8 hours after the manufacture of the soil material mixture 20, or the elapsed time may be set to a time that assumes the time when the spreading process is completed and the compaction process starts immediately, i.e., the time when the CSG is left unattended is 0 hours.

[0080] Alternatively, instead of using elapsed time, the time elapsed from the completion of the spreading process to the start of the compaction process may be used as the actual time the CSG is left unattended during construction, and this time may be set as the unattended time for each section. In this case, the measurement of the unattended time begins at the time the spreading process is completed.

[0081] Once the resting process is complete, that is, once the predetermined elapsed time for each section has elapsed, in the compaction process, as shown in Figure 5(B), the soil material mixture 20 is compacted by compaction machinery (compactor) such as a vibratory roller 28, just as in actual construction.

[0082] After the compaction process is completed, the soil material mixture 20 in each section is cured under predetermined curing conditions for a predetermined period during the curing process. After a sufficient curing period (for example, 2-3 days) has elapsed and the soil material mixture 20 has hardened to a certain extent, it becomes the test structure.

[0083] In the subsequent characteristic measurement process, the density of the test structure is measured as the compaction characteristic of the soil material mixture 20.

[0084] Specifically, first, a cylindrical core (sample) is collected from the test structure using a coring machine. Then, the volume and weight of the collected core are measured, and the density is calculated from the measured volume and weight. If there is a risk of the core collapsing when measuring the volume, the density of the core is measured using an RI densimeter, which irradiates the core with gamma rays and calculates the density of the core from the transmission attenuation rate.

[0085] Furthermore, the density of the test structure may be measured by placing a scattering-type radioisotope densimeter on the upper surface of the test structure, without taking a core sample.

[0086] A scattering-type radioisotope densimeter is installed on the surface of an object to be measured. It emits gamma rays into the object and detects the gamma rays scattered from within the object toward its surface. Since gamma rays disappear more easily at higher densities, the density of the test structure can be calculated by measuring the proportion of gamma rays scattered toward the surface of the test structure relative to the amount of gamma rays emitted into the structure.

[0087] The density is calculated for each test structure, that is, for each soil material mixture 20 that has been spread and compacted in multiple sections with different elapsed times. Therefore, it is possible to understand how the compaction characteristics of the soil material mixture 20 change with different elapsed times (1 hour to 6 hours).

[0088] Furthermore, as a compaction characteristic of the soil material mixture 20, the water content of the test structure and the compressive strength of the test structure may be measured in addition to, or instead of, the density of the test structure.

[0089] In this way, by understanding the compaction characteristics of the soil material mixture 20 according to the elapsed time, even in cases where the time the CSG is left to stand after being spread by a spreading machine and before being compacted by a compaction machine differs depending on the location where the CSG is spread, such as in a trapezoidal CSG dam 100, if the time left to stand at each location where the CSG is spread is recorded, it is possible to determine the compaction characteristics corresponding to the standing time from the results measured by the compaction characteristics measurement method described above. Therefore, even with relatively large structures, the quality of the entire structure can be accurately evaluated by clearly determining the compaction characteristics of each part of the structure.

[0090] Alternatively, instead of recording the time the CSG is left undisturbed, the time elapsed from the time the CSG is manufactured until it is compacted may be recorded for each area where the CSG is laid. In this case, since the recorded elapsed time corresponds to the elapsed time set for each section, it is possible to determine the compaction characteristics corresponding to the recorded elapsed time from the results measured by the compaction characteristics measurement method described above. Therefore, even in this case, the compaction characteristics of each part of a relatively large structure become clear, and the overall quality of the structure can be accurately evaluated.

[0091] According to the second embodiment described above, the following effects and advantages are achieved.

[0092] In the above-described compaction characteristics measurement method, the compaction characteristics of the soil material mixture 20 are measured through a spreading step in which the mixed soil material mixture 20 is spread and leveled, a compaction step in which the spread soil material mixture 20 is compacted after a predetermined elapsed time of 1 hour or more has elapsed since the manufacture of the soil material mixture 20, and a characteristics measurement step in which the compaction characteristics of the compacted soil material mixture 20 are measured.

[0093] By understanding the compaction characteristics of the soil material mixture 20 according to a predetermined elapsed time, even in cases where the time the CSG is left to be compacted differs depending on the location where it is spread, such as in a trapezoidal CSG dam 100, if the time the CSG is left to be spread is recorded for each location where it is spread, the compaction characteristics corresponding to the time the CSG is left to be spread can be determined from the results measured by the compaction characteristics measurement method described above. Therefore, even with relatively large structures, the quality of the entire structure can be accurately evaluated by clearly determining the compaction characteristics of each part of the structure.

[0094] Furthermore, in the compaction characteristic measurement method described above, the soil material mixture 20 is spread and compacted in the test yard in the same manner as spreading and compacting in actual construction. By spreading and compacting the soil material mixture 20 in the same manner as spreading and compacting in actual construction, it becomes possible to grasp the compaction characteristics under conditions close to actual construction, and as a result, the compaction characteristics of the entire structure can be grasped with greater accuracy.

[0095] Furthermore, the following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the second embodiment described above, or to combine the configurations described in the following different modifications.

[0096] The soil material mixture 20 of the second embodiment described above may contain an admixture that has the effect of delaying the setting reaction of cement. The admixture is a so-called setting retarder such as "Frolic T (Frolic is a registered trademark)" (manufactured by Frolic Co., Ltd.), for example, one in which the difference in cement setting time according to JIS A 1147:2019 "Test method for concrete setting time" is approximately +95 minutes at the start time and approximately +100 minutes at the end time. The admixture should be such that the difference in cement setting time according to JIS A 1147:2019 "Test method for concrete setting time" is +0 minutes or more at the start time and +15 minutes or more at the end time.

[0097] Specifically, in the spreading process, soil material mixtures 20 with different amounts of admixture added are spread in multiple sections set to the same length of time, and in the characteristic measurement process, the compaction characteristics of the compacted soil material mixtures 20 are measured. By changing the amount of admixture added to the soil material mixture 20 in this way, it is possible to understand the effect of the admixture on the compaction characteristics.

[0098] Furthermore, by spreading soil material mixtures 20 with the same amount of admixture added into multiple sections set to different elapsed time lengths, and measuring the compaction characteristics of the compacted soil material mixtures 20, it is possible to understand how the compaction characteristics of soil material mixtures 20 with added admixtures change with different elapsed time lengths.

[0099] Furthermore, by comprehensively understanding the changes in the compaction characteristics of the soil material mixture 20 due to differences in elapsed time and the amount of admixture added, even if the amount of admixture added to the CSG differs in each part of the structure, if the amount of admixture added in each part and the time the CSG was left standing or the time elapsed from the time the CSG was manufactured until it was compacted are known, the corresponding compaction characteristics of the CSG can be determined from the results measured by the compaction characteristics measurement method described above.

[0100] Furthermore, in the second embodiment described above, the compaction characteristics of the soil material mixture 20 that has been spread and compacted in the test yard are measured. Alternatively, the measurement of compaction characteristics may be performed on a structure constructed with CSG that has been compacted after a predetermined elapsed time following the spreading process, such as the trapezoidal CSG dam 100, which is an actually constructed structure.

[0101] Specifically, in this case, cores are taken from at least three parts of the trapezoidal CSG dam 100: the part with the shortest CSG retention time (for example, the third layer 13, which had the shortest retention time among the multiple CSG layers 10); the part with the longest CSG retention time (for example, the first layer 11, which had the longest retention time among the multiple CSG layers 10); and a part that can interpolate between these two parts. The density of each of the collected cores is then measured.

[0102] By measuring the density of cores taken from multiple sections of the trapezoidal CSG dam 100 with different CSG retention times, it is possible to understand how the compaction characteristics of the CSG in the trapezoidal CSG dam 100 change depending on the elapsed time from the time the CSG is manufactured until it is compacted.

[0103] Furthermore, by gaining a comprehensive understanding of the compaction characteristics of CSG over time, it becomes possible to easily estimate the compaction characteristics in each part of even relatively large structures like the trapezoidal CSG dam 100, thereby enabling accurate evaluation of the overall quality of the structure.

[0104] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0105] For example, in the above embodiment, the case in which the structure to be evaluated for quality using the compaction characteristic measurement method is a trapezoidal CSG dam 100 was described, but the structure to be evaluated is not limited to this, and may be a dam body such as a sediment control dam or a seawall. Furthermore, any structure that has a structure constructed by the CSG method is not limited to those that constitute a dam or other embankment, but may be any structure. [Explanation of Symbols]

[0106] 10...CSG layer 16. Vibratory roller (compacting machine) 20...Soil material mixture 22...container 24. Electric hammer 26. Bulldozer (leveling machine) 28. Vibratory roller (compacting machine) 100... Trapezoidal CSG Dam (Structure)

Claims

1. A method for measuring compaction properties of a soil material mixture produced by mixing unwashed excavated soil material, cement, and water, wherein the compaction properties of the soil material mixture are measured, A storage step involves placing the mixed soil material mixture into a container, The soil material mixture contained in the container is compacted within one hour after the soil material mixture is manufactured in a primary compaction step, A secondary compaction step is performed in which the soil material mixture contained in the container is compacted after a predetermined elapsed time of one hour or more has elapsed since the manufacture of the soil material mixture. The system includes a characteristic measurement step for measuring the compaction characteristics of the compacted soil material mixture in the container, The compaction energy applied to the soil material mixture in the secondary compaction step is greater than the compaction energy applied to the soil material mixture in the primary compaction step. Method for measuring compaction characteristics.

2. A method for measuring the compaction properties of a soil material mixture produced by mixing excavated soil material, cement, and water, in accordance with JIS A 1204 "Method for testing the particle size distribution of soil," wherein the mass fraction of material passing through a sieve with a nominal size of 0.15 mm exceeds 3%, A storage step involves placing the mixed soil material mixture into a container, The soil material mixture contained in the container is compacted within one hour after the soil material mixture is manufactured in a primary compaction step, A secondary compaction step is performed in which the soil material mixture contained in the container is compacted after a predetermined elapsed time of one hour or more has elapsed since the manufacture of the soil material mixture. The system includes a characteristic measurement step for measuring the compaction characteristics of the compacted soil material mixture in the container, The compaction energy applied to the soil material mixture in the secondary compaction step is greater than the compaction energy applied to the soil material mixture in the primary compaction step. Method for measuring compaction characteristics.

3. The soil material mixture contains an admixture that has the effect of delaying the setting reaction of the cement. In the aforementioned storage step, the soil material mixtures are stored in multiple containers, each containing either the soil material mixture with the same set elapsed time but different amounts of the admixture added, or the soil material mixtures with the same amount of the admixture added but different elapsed time settings. In the characteristic measurement step, the compaction characteristics of the compacted soil material mixture in each of the multiple containers are measured. The method for measuring compaction characteristics according to claim 1 or 2.

4. A method for measuring compaction properties of a soil material mixture produced by mixing unwashed excavated soil material, cement, and water, wherein the compaction properties of the soil material mixture are measured, A spreading step in which the mixed soil material mixture is spread and leveled, A compaction step in which the spread soil material mixture is compacted after a predetermined elapsed time of one hour or more has elapsed since the manufacture of the soil material mixture, The process includes a characteristic measurement step for measuring the compaction characteristics of the compacted soil material mixture, The compaction energy applied to the soil material mixture in the spreading step is less than the compaction energy applied to the soil material mixture in the compaction step. Method for measuring compaction characteristics.

5. A method for measuring the compaction properties of a soil material mixture produced by mixing excavated soil material, cement, and water, in accordance with JIS A 1204 "Method for testing the particle size distribution of soil," wherein the mass fraction of material passing through a sieve with a nominal size of 0.15 mm exceeds 3%, A spreading step in which the mixed soil material mixture is spread and leveled, A compaction step in which the spread soil material mixture is compacted after a predetermined elapsed time of one hour or more has elapsed since the manufacture of the soil material mixture, The process includes a characteristic measurement step for measuring the compaction characteristics of the compacted soil material mixture, The compaction energy applied to the soil material mixture in the spreading step is less than the compaction energy applied to the soil material mixture in the compaction step. Method for measuring compaction characteristics.

6. The soil material mixture contains an admixture that has the effect of delaying the setting reaction of the cement. In the spreading process, the soil material mixtures with different amounts of admixture added are spread in multiple sections where the elapsed time is set to the same length, or the soil material mixtures with the same amount of admixture added are spread in multiple sections where the elapsed time is set to different lengths. In the characteristic measurement step, the compaction characteristics of the compacted soil material mixture in each of the multiple sections are measured. The method for measuring compaction characteristics according to claim 4 or 5.

7. The compaction energy applied to the soil material mixture in the secondary compaction process is set to be equivalent to the compaction energy applied to the soil material mixture by the compaction machine in actual construction. A method for measuring compaction characteristics according to any one of claims 1 to 3.

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