Method for determining the improvement range of a high-pressure injection improved body

Abstract

The objective is to improve the accuracy of determining the improvement range of the high-pressure injection improved body. [Solution] A method for determining the improvement range of a high-pressure injection improved body in which a solidifying agent is mixed with soil, comprising: an estimation step of estimating the temperature rise characteristics when a high-pressure injection improved body 10 solidifies based on the adiabatic temperature rise characteristics when a plurality of improved test specimens S with different unit solidifying agent amounts relative to soil solidify; and a determination step of determining the improvement range of the high-pressure injection improved body 10 based on the estimated temperature rise characteristics of the high-pressure injection improved body 10 and the measured temperature T of the high-pressure injection improved body 10 during construction.

Description

Technical Field

[0001] The present invention relates to a method for determining the improvement range of a high-pressure injection improvement body.

Background Art

[0002] A high-pressure injection improvement method is known in which a solidifying material is high-pressure injected from an injection rod inserted into the ground to form a high-pressure injection improvement body in the ground (see, for example, Patent Documents 1 to 9).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in the case of high-pressure injection-treated ground improvement bodies, for example, the temperature of a predetermined location on the high-pressure injection-treated ground improvement body is measured during construction, and if the measured temperature is above the reference temperature, it is determined that the ground has been improved in the area from the center to that predetermined location and that the high-pressure injection-treated ground improvement body has been formed. In this case, the reference temperature of the high-pressure injection-treated ground improvement body is uniformly set (for example, 40°C) based on empirical rules, etc.

[0005] However, the reference temperature of the high-pressure injection-treated soil improvement body may vary depending on, for example, the amount of solidifying agent per unit of soil. Therefore, setting a uniform reference temperature for the high-pressure injection-treated soil improvement body may reduce the accuracy of determining the improvement range of the high-pressure injection-treated soil improvement body.

[0006] Considering the above facts, the present invention aims to improve the accuracy of determining the improvement range of the high-pressure injection improved body. [Means for solving the problem]

[0007] The method for determining the improvement range of a high-pressure injection-formed improved body according to claim 1 is a method for determining the improvement range of a high-pressure injection-formed improved body in which a solidifying agent is mixed with soil, comprising: an estimation step of estimating the temperature rise characteristics when the high-pressure injection-formed improved body solidifies based on the adiabatic temperature rise characteristics when a plurality of improved test bodies with different unit solidifying agent amounts relative to the soil solidify; and a determination step of determining the improvement range of the high-pressure injection-formed improved body based on the estimated temperature rise characteristics of the high-pressure injection-formed improved body and the measured temperature of the high-pressure injection-formed improved body during construction.

[0008] According to the method for determining the improvement range of a high-pressure injection improved body according to claim 1, in the estimation step, the temperature rise characteristics when the high-pressure injection improved body solidifies are estimated based on the adiabatic temperature rise characteristics when multiple improved test bodies with different unit solidification material amounts relative to soil solidify.

[0009] Next, in the determination process, the improvement range of the high-pressure injection improved body is determined based on the estimated temperature rise characteristics of the high-pressure injection improved body and the measured temperature of the high-pressure injection improved body during construction.

[0010] Thus, in the present invention, by using multiple improved test specimens with different unit solidification amounts in the estimation process, it is possible to estimate the temperature rise characteristics of the high-pressure injection improved body, taking into account the unit solidification amount of the solidification material.

[0011] Furthermore, by determining the improvement range of the high-pressure injection-treated body based on the estimated temperature rise characteristics of the high-pressure injection-treated body and the measured temperature of the high-pressure injection-treated body during construction, the accuracy of determining the improvement range of the high-pressure injection-treated body can be improved.

[0012] The method for determining the improvement range of a high-pressure injection improved body according to claim 2 is the method for determining the improvement range of a high-pressure injection improved body according to claim 1, wherein in the estimation step, the temperature rise characteristics of a predetermined position of the high-pressure injection improved body are estimated based on an analysis model of the high-pressure injection improved body modeled based on the adiabatic temperature rise characteristics of the improved test body.

[0013] According to the method for determining the improvement range of a high-pressure injection improved body according to claim 2, in the estimation step, the temperature rise characteristics of the high-pressure injection improved body are estimated based on an analytical model of the high-pressure injection improved body modeled based on the adiabatic temperature rise characteristics of the improved test body.

[0014] By using this analytical model, it is possible to estimate the temperature rise characteristics at a predetermined position of the high-pressure injection improved body.

[0015] The method for determining the improvement range of a high-pressure injection improved body according to claim 3 is the method for determining the improvement range of a high-pressure injection improved body according to claim 2, wherein the analysis model is provided with at least one of the design improvement diameter of the high-pressure injection improved body, the type of solidifying material, the unit solidifying material amount of the solidifying material, and the soil as parameters.

[0016] According to the method for determining the improvement range of a high-pressure injection improved body according to claim 3, the analysis model is provided with at least one of the following parameters: the design improvement diameter of the high-pressure injection improved body, the unit solidification amount of the solidifying agent, the type of solidifying agent, and the soil.

[0017] As a result, the estimation accuracy of the temperature rise characteristics of the high-pressure injection improvement body can be improved.

[0018] The method for determining the improvement range of the high-pressure injection improvement body according to claim 4 is the method for determining the improvement range of the high-pressure injection improvement body according to claim 1, wherein in the estimation step, based on the temperature rise characteristics of the high-pressure injection improvement body, a reference temperature at a predetermined position in the radial direction of the high-pressure injection improvement body is estimated, and in the determination step, based on the magnitude relationship between the estimated reference temperature of the high-pressure injection improvement body and the measured temperature at the predetermined position of the high-pressure injection improvement body measured during construction, the improvement range of the high-pressure injection improvement body is determined.

[0019] According to the method for determining the improvement range of the high-pressure injection improvement body according to claim 4, in the estimation step, based on the temperature rise characteristics of the high-pressure injection improvement body, a reference temperature at a predetermined position in the radial direction of the high-pressure injection improvement body is estimated.

[0020] Then, in the determination step, based on the magnitude relationship between the estimated reference temperature at the predetermined position of the high-pressure injection improvement body and the measured temperature at the predetermined position of the high-pressure injection improvement body measured during construction, the improvement range of the high-pressure injection improvement body is determined.

[0021] Thus, in the present invention, in the estimation step, by estimating the reference temperature at a predetermined position of the high-pressure injection improvement body, the improvement range of the high-pressure injection improvement body can be easily determined.

[0022] The method for determining the improvement range of the high-pressure injection improvement body according to claim 5 is the method for determining the improvement range of the high-pressure injection improvement body according to claim 1, wherein in the estimation step, based on the temperature rise characteristics of the high-pressure injection improvement body, a reference temperature at the center of the high-pressure injection improvement body is estimated, and in the determination step, based on the magnitude relationship between the estimated reference temperature of the high-pressure injection improvement body and the measured temperature at the center of the high-pressure injection improvement body measured during construction, the improvement range of the high-pressure injection improvement body is determined.

[0023] According to the method for determining the improvement range of a high-pressure injection improved body according to claim 5, in the estimation step, the reference temperature of the center of the high-pressure injection improved body is estimated based on the temperature rise characteristics of the high-pressure injection improved body.

[0024] Then, in the determination process, the improvement range of the high-pressure injection-treated body is determined based on the relationship between the estimated reference temperature of the center of the high-pressure injection-treated body and the measured temperature of the center of the high-pressure injection-treated body measured during construction.

[0025] Thus, in the present invention, by estimating the reference temperature of the center of the high-pressure injection improved body during the estimation process, the improvement range of the high-pressure injection improved body can be easily determined.

[0026] The method for determining the improvement range of a high-pressure injection improved body according to claim 6 is the method for determining the improvement range of a high-pressure injection improved body according to any one of claims 1 to 5, wherein the solidifying agent is a cement-based solidifying agent containing blast furnace slag.

[0027] According to the method for determining the improvement range of a high-pressure injection improved body according to claim 6, the solidifying agent is a cement-based solidifying agent containing blast furnace slag. By using blast furnace slag in this way, it is possible to contribute to decarbonization.

[0028] On the other hand, cement-based solidifying agents containing blast furnace slag tend to have a lower maximum solidification temperature compared to general cement-based solidifying agents that do not contain blast furnace slag. In such cases, the present invention is particularly effective. [Effects of the Invention]

[0029] As described above, the present invention makes it possible to improve the accuracy of determining the improvement range of the high-pressure injection improved body. [Brief explanation of the drawing]

[0030] [Figure 1] This is a vertical cross-sectional view showing a high-pressure injection improved body to which the method for determining the improvement range of a high-pressure injection improved body according to the first embodiment is applied. [Figure 2]This is a longitudinal cross-sectional view showing a test apparatus for a simplified thermal insulation test according to the first embodiment. [Figure 3] This is a cross-sectional view taken along line 3-3 in Figure 2. [Figure 4] This graph shows the results of a simplified thermal insulation test, illustrating the relationship between the amount of solidifying agent per unit area and the maximum temperature of the improved test specimen. [Figure 5] Figure 4 is a graph showing the averaged test results of the simplified insulation test. [Figure 6] (A) and (B) are analytical models in the method for determining the improvement range of a high-pressure injection improved body according to the second embodiment, and are analytical models of the test apparatus for the simplified heat insulation test shown in Figures 2 and 3. [Figure 7] (A) is a perspective view showing a mass improvement test specimen that simulates the high-pressure injection improved body shown in Figure 1, and (B) is a cross-sectional view taken along line 7B-7B in Figure 7. [Figure 8] Figures 7(A) and 7(B) are perspective views showing the analytical model of the mass improvement test specimen. [Figure 9] Figure 8 shows the analysis results of the analysis model of the mass improvement test specimen, and is a graph showing the relationship between time and analysis temperature. [Figure 10] Figure 8 shows the analysis results of the analysis model of the mass improvement test specimen, and is a graph showing the relationship between time and analysis temperature. [Figure 11] This is a vertical cross-sectional view showing a high-pressure injection improved body to which the method for determining the improvement range of the high-pressure injection improved body according to the third embodiment is applied. [Modes for carrying out the invention]

[0031] (First Embodiment) First, I will describe the first embodiment.

[0032] Figure 1 shows a high-pressure injection-treated body 10 to which the method for determining the improvement range of the high-pressure injection-treated body according to the first embodiment is applied. As an example, the high-pressure injection-treated body 10 is formed from soil cement, which is obtained by mixing a solidifying agent (cement-based solidifying agent) with excavated soil obtained by excavating the ground G.

[0033] When constructing the high-pressure injection-type improved ground body 10, first, a hole is formed in the ground G using a drilling rod 12 that also serves as a drilling tool. Next, while rotating the drilling rod 12 inside the hole, a slurry-like solidifying material is injected laterally at high pressure from the tip of the drilling rod 12, and the drilling rod 12 is gradually pulled up. As a result, the ground G is excavated, and the excavated soil and solidifying material are mixed and combined, creating a high-pressure injection-type improved ground body 10 with a predetermined improved diameter r in the ground G.

[0034] Furthermore, multiple measuring tubes 20 are inserted into the ground G surrounding the high-pressure injection-treated body 10. The measuring tubes 20 are positioned, for example, at predetermined radial positions of the high-pressure injection-treated body 10 before its construction. In this embodiment, as an example, multiple measuring tubes 20 are positioned at intervals around the high-pressure injection-treated body 10 at the design improvement diameter R0 position (r=R0) of the high-pressure injection-treated body 10.

[0035] The arrangement and number of measuring tubes 20 can be changed as appropriate. Therefore, the measuring tubes 20 may be provided, for example, on the outside or inside of the design improvement diameter R0 of the high-pressure injection improvement body 10. In addition, multiple measuring tubes 20 may be provided radially, not just in the circumferential direction of the high-pressure injection improvement body 10.

[0036] Each measuring tube 20 is equipped with multiple temperature sensors 22 for measuring the temperature of the high-pressure injection-treated ground improvement body 10 (ground G). The multiple temperature sensors 22 are arranged at intervals along the longitudinal direction of the measuring tube 20, enabling measurement of the temperature of the ground G at a predetermined depth. Each temperature sensor 22 is electrically connected to an observation device 24 installed on the ground. Each temperature sensor 22 outputs the measured temperature T of the high-pressure injection-treated ground improvement body 10 to the observation device 24.

[0037] In this embodiment, after the construction of the high-pressure injection-treated ground improvement body 10, the temperature of the ground G is periodically measured by each temperature sensor 22. If the highest measured temperature T is equal to or greater than the reference temperature T0, it is determined that the area from the central axis C of the high-pressure injection-treated ground improvement body 10 to the temperature measurement position, i.e., the design improvement diameter R0 of the high-pressure injection-treated ground improvement body 10, has been improved. In other words, it is determined that the improvement diameter r of the high-pressure injection-treated ground improvement body 10 is equal to or greater than the design improvement diameter R0.

[0038] Incidentally, the reference temperature T0 of the high-pressure injection improved body 10 may fluctuate depending on, for example, the amount of solidifying agent per unit volume of excavated soil (sand) (hereinafter referred to as "unit solidifying agent amount"). Therefore, if the reference temperature T0 of the high-pressure injection improved body 10 is set uniformly (for example, 40°C), the accuracy of determining the improved range of the high-pressure injection improved body 10 may decrease.

[0039] (Simple insulation test) Therefore, in this embodiment, the reference temperature T0 of the high-pressure injected improved body 10 is estimated based on the adiabatic temperature rise characteristics when the improved test body solidifies, which are obtained from the test results of a simplified adiabatic insulation test. For this reason, an example of a simplified adiabatic insulation test will be described first.

[0040] (Test equipment) Figures 2 and 3 show the test apparatus 30 for a simplified thermal insulation test. The test apparatus 30 periodically measures the temperature (thermal insulation temperature) at which the improved test specimen S solidifies by curing it in a simplified thermal insulation state with minimal influence from the outside temperature. This test apparatus 30 comprises a thermal insulation curing container 32, a temperature sensor 46, and an observation device 48.

[0041] The insulated curing container 32 has an insulated container body 34 and an insulated lid 36. The insulated container body 34 is formed in a box shape from, for example, expanded polystyrene, and has a housing section 34A in the center for housing the improved test specimen S. The insulated container body 34 is housed in a box-shaped wooden formwork 35.

[0042] Insulating material 38, such as rock wool, is provided on the bottom surface and inner wall surface of the housing section 34A of the insulated container body 34. This housing section 34A is sealed and can be opened and closed by an insulating lid 36. The insulating lid 36 is formed in a rectangular parallelepiped shape, for example, from expanded polystyrene. Insulating material 38 is provided on the lower surface of this insulating lid 36.

[0043] The improved test specimen S is composed of multiple test pieces 40. Each of the test pieces 40 is formed from soil cement, which is a mixture of soil and a solidifying agent (cement-based solidifying agent), and is filled into a cylindrical can 42. As an example, the test pieces 40 are also housed at equal intervals in two horizontal directions in the housing section 34A of the insulated container body 34.

[0044] Here, the test piece 40 placed in the center of the housing section 34A of the insulated curing container 32 is affected by heat from multiple test pieces 40 placed around it. Therefore, the temperature of the test piece 40 tends to rise more easily as you move from the outer periphery of the housing section 34A towards the center.

[0045] In this test, as an example, a temperature sensor 46, such as a thermocouple, is embedded in a test piece 40 located in the center of the housing section 34A of the insulated curing container 32. The temperature sensor 46 is embedded, for example, in the center of the test piece 40, and is capable of measuring the temperature of that center. An observation device 48 is electrically connected to the temperature sensor 46. The temperature sensor 46 outputs the measured temperature of the test piece 40 to the observation device 48.

[0046] The temperature sensor 46 is not limited to the test piece 40 located in the center of the housing section 34A of the insulated curing container 32, but may also be provided on other test pieces 40. Furthermore, the temperature sensor 46 can be provided on at least one of multiple test pieces 40.

[0047] Furthermore, in this embodiment, the shape and size of the multiple test pieces 40 are the same. However, the shape and size of the multiple test pieces 40 may be different. Also, the improved test specimen S can be composed of at least one test piece.

[0048] (Exam Overview) In this test, as shown in Table 1, a simple thermal insulation test was conducted on improved test specimens S1 to S18, each with different types of solidifying agent (cement-based solidifying agent), unit solidifying agent quantity, and water-solidifying agent ratio (water-cement ratio). The temperature at which each improved test specimen S1 to S18 solidified (adiabatic temperature) was measured.

[0049] Improved test specimens S1 to S18 correspond to improved test specimen S shown in Figures 2 and 3, and Table 1 shows the type of solidifying agent, the amount of solidifying agent per unit, and the water-solidifying agent ratio for the test piece 40 that constitutes each improved test specimen S1 to S18. In this test, for each improved test specimen S1 to S18, the adiabatic temperature at which the test piece 40, which is placed in the center of the housing section 34A of the insulated container body 34, solidifies was periodically measured by a temperature sensor 46.

[0050] In the following explanation, the improved test specimens S1 to S18 will be collectively referred to as improved test specimen S. Furthermore, improved test specimens S1 to S9 with a blast furnace slag content of 40 to 50% will be designated as Group A, and improved test specimens S10 to S18 with a blast furnace slag content of 60 to 70% will be designated as Group B.

[0051] Group B has a higher carbon dioxide reduction efficiency than Group A. Furthermore, while the mixing ratio of blast furnace type B and blast furnace slag powder in Group B is set at 1:1, this ratio can be adjusted as needed, for example, within a range of 3:1 to 1:3.

[0052] In this embodiment, the solidifying agent contains blast furnace slag. However, the solidifying agent does not necessarily have to contain blast furnace slag. The type of solidifying agent can be changed as appropriate; for example, Portland cement may be used. The water-solidifying agent ratio and the amount of solidifying agent per unit can also be changed as appropriate.

[0053] [Table 1]

[0054] (Test results) Figure 4 shows the maximum temperature Tmax as an adiabatic temperature rise characteristic during solidification of each improved test specimen S1 to S18. Figure 5 shows, as an example, a graph of the average maximum temperature Tmax for groups A and B of the improved test specimens S1 to S18.

[0055] As shown in Figures 4 and 5, the relationship between the type of solidifying agent, the amount of solidifying agent per unit, and the maximum temperature Tmax when the improved test specimens S1 to S18 solidify can be seen. It can also be seen that Group B, which has a higher blast furnace slag content than Group A, has a lower maximum temperature Tmax when the improved test specimens solidify.

[0056] In this embodiment, the parameters of the improved test specimen S are defined as the type of solidifying agent, the water-solidifying agent ratio, and the amount of solidifying agent per unit. However, at least the amount of solidifying agent per unit can be set as a parameter of the improved test specimen S.

[0057] (Method for determining the improvement range of a high-pressure injection improved body) Next, an example of a method for determining the improvement range of a high-pressure injection improved body according to the first embodiment will be described.

[0058] (Estimated process) First, in the estimation process, the maximum temperature Tmax of the improved test specimen S is determined from the test results (graph) of the simplified thermal insulation test shown in Figure 5, according to the type of solidifying agent and the amount of solidifying agent per unit of the high-pressure injection improved body 10 that will actually be constructed on the ground G. Based on this maximum temperature Tmax, the reference temperature T0 at the design improved diameter R0 position of the high-pressure injection improved body 10 is estimated, for example.

[0059] In this case, for example, the design improvement diameter R0 of the high-pressure injection improved body 10, the soil type of the ground G (soil cement), and a coefficient corresponding to the temperature measurement location of the ground G may be multiplied by the maximum temperature Tmax of the improved test specimen S to appropriately correct the reference temperature T0 of the high-pressure injection improved body 10. In other words, the reference temperature T0 of the high-pressure injection improved body 10 can be appropriately set based on the maximum temperature Tmax of the improved test specimen S.

[0060] Furthermore, the reference temperature T0 of the high-pressure injection improved body 10 is not limited to the maximum temperature Tmax at the center of the improved test specimen S, but may also be the maximum temperature Tmax at the radial intermediate part or outer periphery of the improved test specimen S, for example. Also, the simple thermal insulation test may be conducted in advance or when planning the construction of the high-pressure injection improved body 10.

[0061] (Judgment process) Next, in the determination step, the improvement range of the high-pressure injection improved body 10 is determined based on the relationship between the estimated reference temperature T0 of the high-pressure injection improved body 10 and the measured temperature T of the high-pressure injection improved body 10 measured by the temperature sensor 22 during the construction of the high-pressure injection improved body 10.

[0062] Specifically, the estimated reference temperature T0 at the design improvement diameter R0 position of the high-pressure injection improved body 10 is compared with the measured temperature T at the design improvement diameter R0 position, which is periodically measured by the temperature sensor 22 during the construction of the high-pressure injection improved body 10, and it is determined whether the measured temperature T is greater than or equal to the reference temperature T0 (T≧T0).

[0063] In the determination process, the highest of the multiple measured temperatures T may be compared with the reference temperature T0, or each measured temperature T may be compared with the reference temperature T0 individually. Furthermore, the measured temperature T may be a corrected value obtained by multiplying the actual measured temperature T by a coefficient corresponding to the measurement depth, etc.

[0064] When the measured temperature T of the high-pressure jet improvement body 10 is equal to or higher than the reference temperature T0 (T ≥ T0), it is determined that the ground from the central axis C of the high-pressure jet improvement body 10 to the temperature measurement position (the position of the temperature sensor 22) has been improved. On the other hand, when the measured temperature T of the high-pressure jet improvement body 10 is lower than the reference temperature T0 (T < T0), it is determined that the ground improvement at the temperature measurement position is insufficient.

[0065] Note that the estimated position of the reference temperature T0 and the measured position of the measured temperature T of the high-pressure jet improvement body 10 are not limited to the improved diameter R0 position of the high-pressure jet improvement body 10 in design, and can be changed as appropriate.

[0066] (Effect) Next, the effects of the first embodiment will be described.

[0067] As described above, according to the improvement range determination method of the high-pressure jet improvement body according to the present embodiment, in the estimation step, based on the adiabatic temperature rise characteristics when a plurality of improvement test bodies S with different types of solidifying materials, unit solidifying material amounts, and water-solidifying material ratios solidify, the temperature rise characteristics when the high-pressure jet improvement body 10 solidifies are estimated. More specifically, based on the maximum temperature Tmax when the high-pressure jet improvement body 10 solidifies, the reference temperature T0 of the high-pressure jet improvement body 10 is estimated.

[0068] Next, in the determination step, based on the estimated reference temperature T0 of the high-pressure jet improvement body 10 and the measured temperature T of the high-pressure jet improvement body 10 during construction, the improvement range of the high-pressure jet improvement body 10 is determined.

[0069] Thus, in the present embodiment, in the estimation step, by using a plurality of improvement test bodies S with different types of solidifying materials, unit solidifying material amounts, and water-solidifying material ratios, the temperature rise characteristics of the high-pressure jet improvement body 10 considering the type of solidifying material, unit solidifying material amount, and water-solidifying material ratio can be estimated.

[0070] Then, based on the estimated temperature rise characteristics of the high-pressure jet improvement body 10 and the measured temperature T of the high-pressure jet improvement body 10 during construction, by determining the improvement range of the high-pressure jet improvement body 10, the determination accuracy of the improvement range of the high-pressure jet improvement body 10 can be improved.

[0071] Furthermore, by using a cement-based solidification material containing blast furnace slag as the solidification material for the high-pressure injection improved body 10, it is possible to contribute to decarbonization.

[0072] On the other hand, cement-based solidifying agents containing blast furnace slag tend to have a lower maximum solidification temperature compared to general cement-based solidifying agents (ordinary Portland cement) that do not contain blast furnace slag. This embodiment is particularly effective in such cases.

[0073] (Second embodiment) Next, a second embodiment will be described. In the second embodiment, components and the like that have the same configuration as in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0074] In the second embodiment, during the estimation process, the temperature rise characteristics of a predetermined position of the high-pressure injection improved body 10 are estimated based on the analysis model 50M (see Figure 8) of the high-pressure injection improved body 10, which is modeled based on the test results of the simplified thermal insulation test described above.

[0075] (Analysis of temperature rise characteristics of improved test specimens) The analysis model 50M for the high-pressure injection improved body 10 is assigned the adiabatic temperature rise equation obtained from the temperature rise characteristic analysis of the improved test specimen S as the adiabatic temperature rise characteristic of the high-pressure injection improved body 10. Therefore, the temperature rise characteristic analysis of the improved test specimen will be explained first.

[0076] In the analysis of the temperature rise characteristics of the improved test specimen, as an example, K and α in the following adiabatic temperature rise equation (1) are identified based on the test results of a simplified adiabatic test.

number

[0077] Specifically, the adiabatic temperature rise characteristics when the improved test specimen S solidifies are analyzed using the analysis model of the test apparatus 30 for the simplified adiabatic insulation test. Then, K and α are determined by adjusting the parameters a, b, g, and h of the adiabatic temperature rise equation (1) so that the analysis results of the adiabatic temperature rise characteristics are the same as the test results of the simplified adiabatic insulation test.

[0078] (Analysis model of the test device) Figures 6(A) and 6(B) show the analysis model 30M of the test apparatus 30 for the simplified thermal insulation test. The analysis model 30M is an axisymmetric model based on the central axis C of the improved test specimen S. The various parameters of the analysis model 30M (thermal conductivity, initial temperature, etc.) are set as appropriate.

[0079] (Analysis results) Table 2 shows the analysis results for K and α in the adiabatic temperature rise formula (1). In this embodiment, as an example, among the improved test specimens S1 to S18, improved test specimens S4 to S6 (Group A) and S13 to S15 (Group B), which have a water solidification material ratio of 89%, were analyzed.

[0080] [Table 2]

[0081] (Analysis of temperature rise characteristics of high-pressure injection improved body) Next, we will explain the temperature rise characteristics analysis of the high-pressure injection improved body 10.

[0082] In this analysis, the high-pressure injection improved body 10 is modeled, and the temperature rise characteristics of the high-pressure injection improved body 10 at a predetermined position are analyzed (estimated).

[0083] In this embodiment, as an example, an analysis model of a mass-improved test specimen that simulates the high-pressure-injection-improved body 10 was used as the analysis model for the high-pressure-injection-improved body 10. The analysis model was evaluated by comparing the test results of a simplified thermal insulation test of the mass-improved test specimen with the analysis results of the analysis model. Therefore, the simplified thermal insulation test of the mass-improved test specimen will be described first.

[0084] Furthermore, the analysis model of the high-pressure injection improved body 10 is not limited to the mass improved test specimen and can be modified as appropriate; for example, the high-pressure injection improved body 10 may be modeled directly.

[0085] (Simplified thermal insulation test of improved mass test specimens) In the simplified thermal insulation test of the mass-improved test specimen, a mass-improved test specimen simulating the high-pressure injection improved specimen 10 was formed in an underground pit where the influence of outside temperature was minimal, and the thermal insulation temperature when the mass-improved test specimen solidified was measured periodically.

[0086] (Improved Mass Test Specimen) Figures 7(A) and 7(B) show the mass improvement test specimen 50. The mass improvement test specimen 50 is formed in a cubic shape from the standpoint of manufacturing and other considerations. In this embodiment, as an example, the unit solidification material amount is 275 kg / m³. 3 Mass-improved test specimens 50 corresponding to improved test specimens S5 (group A) and S14 (group B) were formed.

[0087] The measurement locations P1 to P4 for the adiabatic temperature of the improved mass test specimen 50 were, as an example, four points including the central axis C and the outer surface of the improved mass test specimen 50.

[0088] (Analysis model of improved mass test specimens) Figure 8 shows the analytical model 50M of the mass improvement test specimen 50. The analytical model 50M is a 1 / 4 scale three-dimensional axisymmetric model based on the central axis C of the mass improvement test specimen 50. In addition, the insulation material 52 and floor concrete 54 are modeled around the analytical model 50M. Note that the insulation material 52 and floor concrete 54 are not shown in Figures 7(A) and 7(B).

[0089] The analysis model 50M is provided with various specifications for the improved mass test specimen 50, and the adiabatic temperature rise formula (1), which includes K and α obtained from the temperature rise characteristic analysis of the improved test specimens S5 (group A) and S14 (group B) mentioned above, as the adiabatic temperature rise characteristic of the improved mass test specimen 50.

[0090] The analysis positions P1 to P4 for the temperature rise characteristics (adiabatic temperature) of the analysis model 50M are the same as the measurement positions P1 to P4 for the adiabatic temperature of the mass-improved test specimen 50, and include the central axis C of the analysis model 50M and the outer surface (boundary surface) 50M1.

[0091] Furthermore, when modeling the high-pressure injection-treated ground improvement specimen 10 that will actually be constructed, rather than the mass improvement test specimen 50, at least one of the various parameters such as the design improvement diameter R0 of the high-pressure injection-treated ground improvement specimen 10, the unit amount of solidifying agent, the type of solidifying agent, and the soil (original ground) will be assigned to the analysis model of the high-pressure injection-treated ground improvement specimen 10.

[0092] (Analysis results) Figure 9 shows the analysis results of the temperature rise characteristic analysis of analysis model 50M corresponding to improved test specimen S5 (group A). ​​Figure 10 shows the analysis results of the temperature rise characteristic analysis of analysis model 50M corresponding to improved test specimen S14 (group B).

[0093] Furthermore, Table 3 below shows, as an example, the maximum temperatures of the central axis C (analysis position P1) and the outer surface 50M1 (analysis position P4) of each analysis model 50M.

[0094] [Table 3]

[0095] (Evaluation of the analytical model) The analysis results for each analysis model 50M shown in Figures 9 and 10 were the same as the test results for the simplified thermal insulation test of the mass-improved test specimen 50 (not shown). The evaluation of analysis model 50M using the mass-improved test specimen 50 can be performed as needed and may be omitted as appropriate.

[0096] (Method for determining the improvement range of a high-pressure injection improved body) Next, an example of a method for determining the improvement range of a high-pressure injection improved body according to the second embodiment will be described.

[0097] (Estimated process) First, in the estimation process, the temperature rise characteristics of a predetermined position of the high-pressure injection improved body 10 (mass improved test specimen 50) are estimated based on the analysis model 50M of the high-pressure injection improved body 10 (mass improved test specimen 50) described above. In this embodiment, as an example, the maximum temperature Tmax at the outer surface of the high-pressure injection improved body 10, i.e., at the position of the design improved diameter R0 of the high-pressure injection improved body 10, is estimated, and based on this maximum temperature Tmax, for example, the reference temperature T0 at the position of the design improved diameter R0 of the high-pressure injection improved body 10 is estimated.

[0098] (Judgment process) Next, as shown in Figure 1, in the determination step, the improvement range of the high-pressure injection improved body 10 is determined based on the relationship between the estimated reference temperature T0 of the high-pressure injection improved body 10 and the measured temperature T of the high-pressure injection improved body 10 measured by the temperature sensor 22 during the construction of the high-pressure injection improved body 10.

[0099] Specifically, the reference temperature T0 at the position of the design improvement diameter R0 of the estimated high-pressure injection improvement body 10 is compared with the measured temperature T at the position of the design improvement diameter R0 of the high-pressure injection improvement body 10 measured by the temperature sensor 22 during the construction of the high-pressure injection improvement body 10, and it is determined whether the measured temperature T is equal to or higher than the reference temperature T0 (T≧T0).

[0100] In the determination step, the highest temperature among the plurality of measured temperatures T and the reference temperature T0 may be compared, or each measured temperature T and the reference temperature T0 may be compared. Further, the measured temperature T may be, for example, a corrected value obtained by multiplying the actual measured temperature T by a coefficient corresponding to the measurement depth or the like.

[0101] When the measured temperature T of the high-pressure injection improvement body 10 is equal to or higher than the reference temperature T0 (T≧T0), it is determined that the ground within the range from the central axis C of the high-pressure injection improvement body 10 to the temperature measurement position (the position of the temperature sensor 22) has been improved. On the other hand, when the measured temperature T of the high-pressure injection improvement body 10 is lower than the reference temperature T0 (T<T0), it is determined that the ground improvement at the temperature measurement position is insufficient.

[0102] (Effect) Next, the effects of the second embodiment will be described.

[0103] As described above, according to the improvement range determination method of the high-pressure injection improvement body according to the present embodiment, in the estimation step, based on the analysis model 50M of the high-pressure injection improvement body 10 (mass improvement test body 50) modeled based on the adiabatic temperature rise characteristics of the improvement test body S, the temperature rise characteristics of the high-pressure injection improvement body 10 are estimated.

[0104] By using the analysis model 50M of the high-pressure injection improvement body 10 in this way, the temperature rise characteristics (maximum temperature Tmax) at a predetermined position of the high-pressure injection improvement body 10 can be easily estimated.

[0105] Furthermore, by assigning at least one of the following parameters to the analysis model 50M of the high-pressure injection improved body 10: the design improvement diameter R0 of the high-pressure injection improved body 10, the unit amount of solidifying material, the type of solidifying material, and the soil type, the accuracy of estimating the temperature rise characteristics of the high-pressure injection improved body 10 can be improved.

[0106] Furthermore, in this embodiment, in the estimation step, a reference temperature T0 of a predetermined radial position on the high-pressure injection improved body 10, more specifically the outer circumferential surface of the high-pressure injection improved body 10 (design improved diameter R0 position), is estimated based on the temperature rise characteristics of the high-pressure injection improved body 10.

[0107] Then, in the determination process, the improvement range of the high-pressure injection improved body 10 is determined based on the relationship between the estimated reference temperature T0 at the design improvement diameter R0 position of the high-pressure injection improved body 10 and the measured temperature T at the design improvement diameter R0 position of the high-pressure injection improved body 10 measured during construction.

[0108] Thus, in this embodiment, the improvement range of the high-pressure injection improved body 10 can be easily determined by estimating the reference temperature T0 at the design improvement diameter R0 position of the high-pressure injection improved body 10 during the estimation process.

[0109] (Third embodiment) Next, a third embodiment will be described. In the third embodiment, components and the like that have the same configuration as in the first and second embodiments will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0110] Figure 11 shows a high-pressure injection-treated body 10 to which the improvement range determination method for high-pressure injection-treated bodies according to the third embodiment is applied. In this embodiment, after the construction of the high-pressure injection-treated body 10, the temperature of the central part of the high-pressure injection-treated body 10 is measured.

[0111] Specifically, as shown in Figure 11, after the construction rod 12 is withdrawn from the center of the high-pressure injection-reinforced ground improvement body 10, a measuring tube 60 is quickly inserted into the center. Multiple temperature sensors 62 for measuring the temperature of the high-pressure injection-reinforced ground improvement body 10 (ground G) are attached to the measuring tube 60. Each temperature sensor 62 is, for example, a thermocouple.

[0112] Multiple temperature sensors 62 are arranged at intervals along the longitudinal direction of the measuring tube 60, enabling measurement of the temperature of the high-pressure injection improved body 10 at a predetermined depth. Each temperature sensor 62 is electrically connected to an observation device 64 located on the ground. Each temperature sensor 62 outputs the measured temperature T of the high-pressure injection improved body 10 to the observation device 64.

[0113] (Method for determining the improvement range of a high-pressure injection improved body) Next, an example of a method for determining the improvement range of a high-pressure injection improved body according to the third embodiment will be described.

[0114] (Estimated process) First, in the estimation process, similar to the first embodiment, the maximum temperature Tmax of the improved test specimen S is determined from the test results of the simplified thermal insulation test shown in Figure 5, according to the type of solidifying agent and the amount of solidifying agent per unit of the high-pressure injection improved body 10 to be actually constructed on the ground G. Based on this maximum temperature Tmax, the reference temperature T0 of the center of the high-pressure injection improved body 10 is estimated.

[0115] In this case, for example, the design improvement diameter R0 of the high-pressure injection improved body 10, the soil type of the ground G (soil cement), and a coefficient corresponding to the temperature measurement location of the ground G may be multiplied by the maximum temperature Tmax of the improved test specimen S to appropriately correct the reference temperature T0 of the high-pressure injection improved body 10. In other words, the reference temperature T0 of the high-pressure injection improved body 10 can be appropriately set based on the maximum temperature Tmax of the improved test specimen S.

[0116] (Judgment process) Next, as shown in Figure 11, in the determination step, the improvement range of the high-pressure injection improved body 10 is determined based on the relationship between the estimated reference temperature T0 of the high-pressure injection improved body 10 and the measured temperature T of the high-pressure injection improved body 10 measured by the temperature sensor 62 during the construction of the high-pressure injection improved body 10.

[0117] Specifically, the estimated reference temperature T0 at the center of the high-pressure injection-treated body 10 is compared with the measured temperature T at the center of the high-pressure injection-treated body 10 measured by the temperature sensor 62 during the construction of the high-pressure injection-treated body 10, and it is determined whether the measured temperature T is less than or equal to the reference temperature T0 (T ≤ T0).

[0118] In the determination process, the highest of the multiple measured temperatures T may be compared with the reference temperature T0, or each measured temperature T may be compared with the reference temperature T0 individually. Furthermore, the measured temperature T may be a corrected value obtained by multiplying the actual measured temperature T by a coefficient corresponding to the measurement depth, etc.

[0119] Here, if the improved diameter (improvement range) r of the high-pressure injection improved body 10 becomes larger than the design improved diameter R0, the solidifying agent content per unit volume decreases in the center of the high-pressure injection improved body 10, and the maximum temperature at which the high-pressure injection improved body 10 solidifies decreases. Therefore, the measured temperature (maximum measured temperature) T in the center of the high-pressure injection improved body 10 becomes less than the reference temperature T0 (T <T0)となる。

[0120] On the other hand, if the improved diameter r of the high-pressure injection improved body 10 becomes smaller than the design improved diameter R0, the solidifying agent content per unit volume increases in the center of the high-pressure injection improved body 10, and the maximum temperature at which the high-pressure injection improved body 10 solidifies rises. As a result, the measured temperature (maximum measured temperature) T in the center of the high-pressure injection improved body 10 exceeds the reference temperature T0 (T>T0).

[0121] Therefore, as described above, when the measured temperature T at the center of the high-pressure injection improvement body 10 is less than or equal to the reference temperature T0 (T ≦ T0), it is determined that the improved diameter r of the high-pressure injection improvement body 10 is greater than or equal to the designed improved diameter R0 (r ≧ R0). On the other hand, when the measured temperature T at the center of the high-pressure injection improvement body 10 exceeds the reference temperature T0 (T > T0), it is determined that the improved diameter r of the high-pressure injection improvement body 10 is less than the designed improved diameter R0 (r < R0).

[0122] (Effect) Next, the effects of the third embodiment will be described.

[0123] As described above, according to the method for determining the improvement range of the high-pressure injection improvement body according to the present embodiment, in the estimation step, the reference temperature T0 at the center of the high-pressure injection improvement body 10 is estimated based on the temperature rise characteristic of the high-pressure injection improvement body 10.

[0124] And in the determination step, based on the magnitude relationship between the estimated reference temperature T0 at the center of the high-pressure injection improvement body 10 and the measured temperature T at the center of the high-pressure injection improvement body 10 measured during construction, the improvement range of the high-pressure injection improvement body 10 is determined.

[0125] Thus, in the present embodiment, in the estimation step, by estimating the reference temperature T0 at the center of the high-pressure injection improvement body 10, the improvement range of the high-pressure injection improvement body 10 can be easily determined.

[0126] Also, when measuring the temperature at the center of the high-pressure injection improvement body 10, by inserting the measurement pipe 20 into the hole trace where the construction rod 12 was inserted, the temperature at the center of the high-pressure injection improvement body 10 can be easily measured.

[0127] In the present embodiment, in the determination step, when the measured temperature T of the high-pressure injection improvement body 10 is less than or equal to the reference temperature T0 (T ≦ T0), it is determined that the improved diameter R of the high-pressure injection improvement body 10 is greater than or equal to the designed improved diameter R0. However, for example, an upper limit value as well as a lower limit value may be set for the measured temperature T of the high-pressure injection improvement body 10.

[0128] Specifically, in the estimation step, the reference temperature T0 when the improved diameter r of the high-pressure injection improvement body 10 is set to the designed improved diameter R0, and the reference temperature (hereinafter referred to as "allowable reference temperature T1") when the improved diameter r of the high-pressure injection improvement body 10 is set to an allowable improved diameter R1 (for example, not more than 1.5 times the designed improved diameter R0) larger than the designed improved diameter R0 are estimated.

[0129] And in the determination step, when the measured temperature T of the high-pressure injection improvement body 10 is not less than the allowable reference temperature T1 and not more than the reference temperature T0 (T1 ≤ T ≤ T0), it is determined that the improved diameter r of the high-pressure injection improvement body 10 is not less than the designed improved diameter R0 and not more than the allowable improved diameter R1 (R0 ≤ r ≤ R1).

[0130] On the other hand, when the measured temperature T of the high-pressure injection improvement body 10 is less than the allowable reference temperature T1 or exceeds the reference temperature T0 (T < T1 or T > T0), it is determined that the improved diameter r of the high-pressure injection improvement body 10 exceeds the allowable improved diameter R1 or is less than the designed improved diameter R0.

[0131] Thereby, it is possible to confirm whether the improved diameter r is the high-pressure injection improvement body 10 whose improved diameter is not less than the designed improved diameter R0 and not more than the allowable improved diameter R1 (R0 ≤ r ≤ R1).

[0132] In addition, in the present embodiment, in the estimation step, similar to the first embodiment, the heat insulation temperature rise characteristic of the high-pressure injection improvement body 10 was estimated based on the test result of the simple heat insulation test. However, in the present embodiment, for example, in the estimation step, similar to the second embodiment, the temperature rise characteristic of the high-pressure injection improvement body 10 may be estimated based on the analysis model of the high-pressure injection improvement body 10 modeled based on the heat insulation temperature rise characteristic of the improved test body S.

[0133] As described above, although one embodiment of the present invention has been described, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be appropriately combined and used, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.

Explanation of Reference Numerals

[0134] 10. High-pressure injection improved body 50M Analysis Model (Analysis Model for High-Pressure Injection Improved Body) S Improved Test Specimen S1~S18 Improved Test Specimens

Claims

1. A method for determining the improvement range of a high-pressure injection-treated improved body in which a solidifying agent is mixed with soil, An estimation step of estimating the temperature rise characteristics when the high-pressure injection improved body solidifies, based on the adiabatic temperature rise characteristics when multiple improved test specimens with different unit amounts of solidifying material relative to the soil solidify, A determination step to determine the improvement range of the high-pressure injection improved body based on the estimated temperature rise characteristics of the high-pressure injection improved body and the measured temperature of the high-pressure injection improved body during construction, A method for determining the improvement range of a high-pressure injection improved body.

2. In the estimation step, the temperature rise characteristics at a predetermined position of the high-pressure injection improved body are estimated based on the analysis model of the high-pressure injection improved body modeled based on the adiabatic temperature rise characteristics of the improved test body. A method for determining the improvement range of a high-pressure injection improved body according to claim 1.

3. The analysis model is provided with at least one of the following parameters: the design improvement diameter of the high-pressure injection improved body, the type of solidifying agent, the unit solidifying amount of the solidifying agent, and the amount of soil. A method for determining the improvement range of a high-pressure injection improved body according to claim 2.

4. In the estimation step described above, the reference temperature at a predetermined radial position in the high-pressure injection improved body is estimated based on the temperature rise characteristics of the high-pressure injection improved body. In the determination step, the improvement range of the high-pressure injection improved body is determined based on the relationship between the estimated reference temperature of the high-pressure injection improved body and the measured temperature at the predetermined position of the high-pressure injection improved body measured during construction. A method for determining the improvement range of a high-pressure injection improved body according to claim 1.

5. In the estimation step, the reference temperature of the center of the high-pressure injection improved body is estimated based on the temperature rise characteristics of the high-pressure injection improved body. In the determination step, the improvement range of the high-pressure injection improved body is determined based on the relationship between the estimated reference temperature of the high-pressure injection improved body and the measured temperature of the center of the high-pressure injection improved body measured during construction. A method for determining the improvement range of a high-pressure injection improved body according to claim 1.

6. The solidifying agent is a cement-based solidifying agent containing blast furnace slag. A method for determining the improvement range of a high-pressure injection improved body according to any one of claims 1 to 5.

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