Quality control method for soil impermeable layers

Abstract

To provide a quality control method of a soil impermeable layer capable of controlling quality of a soil impermeable layer more efficiently and with higher precision than conventional methods.SOLUTION: A quality control method of a soil impermeable layer includes at least: an RI scanning estimation step of estimating a degree of compaction and / or a permeability coefficient of the soil impermeable layer by moving RI scanning means 100 to measure in a construction range of the soil impermeable layer; an RI scanning determination step of determining whether or not the degree of compaction and / or the permeability coefficient obtained by the RI scanning estimation step satisfies an RI scanning quality standard; a test hole type estimation step of estimating the degree of compaction by a sand substitution method or a sand pushing method when it is determined that the RI scanning quality standard is not satisfied in the RI scanning determination step; and a test hole type determination step of determining whether or not the degree of compaction obtained by the test hole type estimation step satisfies a test hole type quality standard.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for quality control of a soil water impermeable layer, such as the degree of compaction and the coefficient of permeability of the soil water impermeable layer. [Background technology]

[0002] In the past, waste disposal sites and other facilities required the installation of soil impermeable layers to prevent the leakage and diffusion of pollutants, and bentonite-mixed soil was often used as the impermeable material for these soil impermeable layers. The quality control items for this bentonite-mixed soil include the degree of compaction (density) and the coefficient of permeability after compaction using a roller compactor. The specified values ​​that must be met for the degree of compaction and the coefficient of permeability are set by each relevant organization as quality control standards.

[0003] The degree of compaction can be measured by the conventional sand displacement method or by an RI meter. When using a transmission-type RI meter, a hole about 20 cm deep is drilled at the measurement location and a gamma ray source rod is inserted. After the measurement, the drilled hole must be firmly backfilled. The permeability coefficient is determined by taking a block sample on-site, shaping it in a laboratory, and then placing it in a mold for the permeability test.

[0004] Recently, it has been proposed to use a scattering-type RI measuring device to acquire measurement data over a wide area (see Patent Document 1). Specifically, the scattering-type RI measuring device is installed on a road roller, and the density of the ground is measured continuously while the roller is moving. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-067297 Summary of the Invention [Problem to be solved by the invention]

[0006] However, measurements using the sand replacement method and transmission-type RI measuring device described above are performed over a very wide area of ​​the construction surface at a set frequency and within a set range, and are merely the management of representative points. Therefore, due to variations in the strength of the reference surface or variations in the bentonite mixed soil, there is a possibility that areas where measurements (tests) have not been performed may not meet the specified values.

[0007] In other words, the performance required of a soil water barrier layer is low permeability, and if even a small portion does not meet the standard value, the required water barrier performance cannot be guaranteed for the entire construction area. Therefore, it is impossible to control the compaction quality of the entire construction area of ​​a soil water barrier layer by measuring the density in-situ at a representative location.

[0008] Furthermore, sampling-based permeability tests require a test period of about one month, during which the next process of laying the waterproof sheet may begin. In this case, if it turns out that the results of the permeability test do not meet the specified values, it may become even more difficult to re-install the soil waterproof layer, which will have a major negative impact on the entire process.

[0009] Furthermore, in the measurement method using the mobile scattering-type RI meter disclosed in Patent Document 1, the measurement integration time is short and the variance in measured values ​​is greater than with a transmission-type RI meter, so it is necessary to set stricter standards for pass / fail judgment. As a result, there is a high possibility that areas judged to be below the standard value by the mobile scattering-type RI meter actually meet the original quality control standard value, which could lead to unnecessary re-application.

[0010] In view of the above-mentioned various problems, an object of the present invention is to provide a quality control method for a soil water shielding layer, which is capable of controlling the quality of the soil water shielding layer more efficiently and with higher accuracy than conventional methods. [Means for solving the problem]

[0011] The invention pertaining to (1) is a quality control method for a soil water shielding layer, comprising at least an RI scanning estimation step of estimating the degree of compaction and / or the permeability coefficient of the soil water shielding layer by moving and measuring an RI scanning means within the construction range of the soil water shielding layer; an RI scanning determination step of determining whether the degree of compaction and / or the permeability coefficient obtained by the RI scanning estimation step satisfy the RI scanning quality standard; a test hole type estimation step of estimating the degree of compaction by a sand replacement method or a sand pounding method if it is determined in the RI scanning determination step that the degree of compaction does not satisfy the RI scanning quality standard; and a test hole type determination step of determining whether the degree of compaction obtained by the test hole type estimation step satisfies the test hole type quality standard, wherein if it is determined in the test hole type determination step that the degree of compaction does not satisfy the test hole type quality standard, the soil water shielding layer is re-compacted or stripped and re-constructed.

[0012] According to the invention related to (1) above, the quality of the soil water shielding layer is screened over a wide area by continuous mobile measurement using the RI scanning means, and if it is determined that the RI scanning quality standard is not met, the degree of compaction is judged by the sand replacement method or the sand pounding method. Then, depending on the judgment result, the soil water shielding layer is re-compacted or stripped and re-constructed, so that poorly constructed areas can be picked up and re-compacted or stripped and re-constructed efficiently without unnecessary re-construction.

[0013] The invention related to (2) is a quality control method for a soil water barrier layer described in (1) above, in which the allowable limit of the test hole mold quality standard is a specified value required for the soil water barrier layer, and the allowable limit of the RI scanning quality standard is on the safer side than the allowable limit of the test hole mold quality standard.

[0014] According to the invention related to (2) above, by setting the allowable limit of the RI scanning quality standard to be safer than the allowable limit of the test hole type quality standard, it is possible to more reliably guarantee the required performance throughout the entire construction area.

[0015] The invention according to (3) includes an RI scanning estimation step of estimating the degree of compaction and / or the permeability coefficient of the soil water shielding layer by moving and measuring an RI scanning means within the construction range of the soil water shielding layer; an RI scanning determination step of determining whether the degree of compaction and / or the permeability coefficient obtained by the RI scanning estimation step satisfy an RI scanning quality standard; a fixed RI estimation step of estimating the degree of compaction and / or the permeability coefficient by a fixed RI measuring means when it is determined in the RI scanning determination step that the degree of compaction and / or the permeability coefficient do not satisfy the RI scanning quality standard; and This quality control method for a soil water shielding layer comprises at least a fixed RI determination step for determining whether the coefficient satisfies the fixed RI quality standard; a test hole type estimation step for estimating the degree of compaction by the sand replacement method or the sand pounding method if it is determined in the fixed RI determination step that the coefficient does not satisfy the fixed RI quality standard; and a test hole type determination step for determining whether the degree of compaction obtained in the test hole type estimation step satisfies the test hole type quality standard, wherein if it is determined in the test hole type determination step that the test hole type quality standard is not satisfied, the soil water shielding layer is re-compacted or stripped and re-applied.

[0016] According to the invention related to (3) above, the quality of the soil water barrier layer is screened on a surface basis by continuous mobile measurements using an RI scanning means, and if it is determined that the RI scanning quality standard is not met, a judgment is made using a fixed RI measurement means, and further judgment is made using the sand replacement method or sand pounding method, and by estimating and judging the degree of compaction and / or the hydraulic conductivity in stages, poorly constructed areas can be identified and efficiently re-compacted or stripped and re-constructed without unnecessary re-construction, etc.

[0017] The invention related to (4) is a quality control method for a soil water barrier layer described in (3) above, in which the allowable limit of the test hole type quality standard is a specified value required for the soil water barrier layer, the allowable limit of the fixed RI quality standard is safer than the allowable limit of the test hole type quality standard, and the allowable limit of the RI scanning quality standard is safer than the allowable limit of the fixed RI quality standard.

[0018] According to the invention related to (4) above, by setting the allowable limit of the fixed RI quality standard to the safer side than the allowable limit of the test hole type quality standard, and further setting the allowable limit of the RI scanning quality standard to the safer side than the allowable limit of the fixed RI quality standard, it becomes possible to more reliably guarantee the required performance of the entire construction area.

[0019] The invention related to (5) is a quality control method for a soil water barrier layer described in any one of (1) to (4) above, wherein the RI scanning estimation process includes a distance measurement process for measuring the distance between the measurement surface of the RI scanning means and the surface of the soil water barrier layer, and a correction process for correcting the estimated value of the degree of compaction and / or the permeability coefficient based on the distance measured in the distance measurement process.

[0020] According to the invention related to (5) above, it is possible to reduce measurement errors caused by the distance between the measurement surface of the RI scanning means and the surface of the soil water barrier layer, thereby making it possible to estimate the degree of compaction and / or the permeability coefficient with higher accuracy.

[0021] The invention according to (6) is the quality control method for a soil water barrier layer according to the above (5), wherein the RI scanning estimation step includes a heat map creation step of creating a heat map of the construction range of the soil water barrier layer based on the estimated value of the degree of compaction and / or the permeability coefficient.

[0022] According to the invention related to (6) above, a heat map of the construction area of ​​the soil water barrier layer is created based on the estimated value of the degree of compaction and / or the permeability coefficient, so that the existence of poorly constructed areas can be visualized, and measurements and tests for quality confirmation, re-compaction, stripping and re-construction, etc. can be efficiently carried out. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a side view of an RI scanning means in one embodiment of the present invention. [Figure 2] FIG. 2 is a top view of an RI scanning means in one embodiment of the present invention. [Figure 3]1 is a configuration diagram illustrating a system configuration for quality control according to an embodiment of the present invention. [Figure 4] 1 illustrates a flow diagram of a quality control method in accordance with one embodiment of the present invention. [Figure 5] 1A and 1B are diagrams illustrating a method for estimating the permeability coefficient in one embodiment of the present invention, in which (a) shows a graph illustrating the relationship between the effective bentonite void ratio and the permeability coefficient, and (b) shows a formula for calculating the effective bentonite void ratio. [Figure 6] (a) is a plan view illustrating the moving measurement procedure of the RI scanning means in one embodiment of the present invention, and (b) is a diagram illustrating the display mode of the heat map in one embodiment of the present invention. [Figure 7] 1(a) shows a graph of the relationship between clearance and converted wet density in one embodiment of the present invention, and FIG. 1(b) shows a graph of the relationship between clearance and converted moisture content in one embodiment of the present invention. [Figure 8] 1 is a plan view illustrating a movement measurement procedure of an RI scanning means in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the quality control method for a soil water impermeable layer of the present invention will be described with reference to the drawings.

[0025] FIG. 1 shows a side view of an RI scanning means 100 according to an embodiment of the present invention, and FIG. 2 shows a top view of the RI scanning means 100. As shown in FIG.

[0026] As shown in the figure, the RI scanning means 100 of this embodiment has four wheels 106 with axles 108 as rotation axes attached to pillars 104 extending from an upper frame 102, allowing it to travel on the surface of the soil water barrier layer.

[0027] In addition, a lower frame 110 is provided which is suspended from the upper frame 102 by a band 116 which can be stretched in the vertical direction, and the lower frame 110 is provided with four auxiliary wheels 112 which rotate around axles 114.

[0028] The lower frame 110 described above is provided with a radiation source 118 that emits gamma rays and neutron rays, a detector 120 that detects the gamma rays and neutron rays, and, as shown in Figure 1, a laser measuring instrument 122 that measures the distance (clearance) between the measurement surface of the RI scanning means 100 (the bottom surface of the lower frame 110) and the surface of the soil water barrier layer.

[0029] With the above-described configuration, the auxiliary wheels 112 can be moved in response to the undulations on the surface of the soil water-blocking layer, and gamma rays and neutron rays that penetrate the soil can be continuously detected while moving the RI scanning means 100.

[0030] Also provided on the upper frame 102 are a position detection unit 124 made up of a GNSS receiver and a management / control unit 126 capable of executing measurement control in the RI scanning means 100.

[0031] 3 shows an outline of the system configuration for quality control in this embodiment. The detector 120 described above includes a density measuring unit 1201 capable of detecting gamma rays to measure wet density, and a moisture measuring unit 1202 capable of detecting neutron rays to measure moisture content. Measurement data output from these measuring units is transmitted to a management / control unit 126, which records, analyzes, calculates, and outputs the measurement data. Additionally, the management / control unit 126 and the position detection unit 124 are connected, making it possible to link and record measurement data with measurement position information.

[0032] The management / control unit 126 does not necessarily have to be installed in the RI scanning means 100, but may be configured to record, analyze, calculate, and output measurement data by connecting wirelessly or via a wire to the equipment installed in the RI scanning means 100, for example.

[0033] The RI scanning means 100 may be configured to be towed by a vehicle or the like, or may be configured to be self-propelled by adding a power unit to the RI scanning means 100. In addition, the RI scanning means 100 may be configured to be able to change direction by adding a steering mechanism. Furthermore, the RI scanning means 100 may be configured to be towed so that it can move while sliding on the surface of the soil water barrier layer without providing the auxiliary wheels 112 and / or wheels 106.

[0034] (Quality control flow) Generally, the standard values ​​established as quality control standards for soil impermeable layers at controlled waste disposal sites are a thickness of 50 cm or more and a permeability coefficient of 1 x 10 -8 In addition, the standard value for the degree of compaction is usually that the in-situ dry density is required to be 90% or more of the maximum dry density (degree of compaction).

[0035] Therefore, in the quality control method of this embodiment, when constructing the soil water impermeable layer, quality control is performed for each predetermined rolled-out thickness (for example, 25 to 30 cm) based on the flow chart shown in Fig. 4. The quality control method of this embodiment will be described below based on the flow chart of Fig. 4.

[0036] When compaction of a certain layer of the soil water-blocking layer by the rolling machine is completed, for example, as shown in Fig. 6(a), mobile measurement is performed by the RI scanning means 100 within the construction range of the soil water-blocking layer (step S100). Then, the measurement data measured by the RI scanning means 100 is calculated to calculate the wet density and moisture content (step S101).

[0037] In this embodiment, when calculating the wet density and moisture content in step S101, the actually measured wet density and moisture content are corrected based on the distance (clearance) between the measurement surface of the RI scanning means 100 (the bottom surface of the lower frame 110) and the surface of the soil water shielding layer, as measured by the laser measuring instrument 122, in order to reduce measurement errors due to the distance (clearance).

[0038] More specifically, experimental measurements were conducted in advance using the RI scanning means 100 to investigate the relationship between the clearance and the converted wet density and converted moisture content. For example, Figure 7(a) shows a graph of the relationship between the clearance and converted wet density, and Figure 7(b) shows a graph of the relationship between the clearance and converted moisture content, with data plotted for each sample at the degree of compaction (Dc shown) and the optimal moisture content (Wopt). As can be seen from these graphs, the clearance and the converted wet density and converted moisture content are approximately linearly related, so these relationship equations were determined, and the wet density and moisture content when the clearance is "0 mm" were calculated.

[0039] Next, the hydraulic conductivity of the soil water-blocking layer is estimated based on the hydraulic conductivity estimation equation prepared in advance (step S102). More specifically, as shown in FIG. 5(a), there is a high correlation between the effective bentonite void ratio and the hydraulic conductivity. Therefore, the effective bentonite void ratio can be calculated using the relational equation shown in FIG. 5(b) based on the properties of the water-blocking material (bentonite-mixed soil) and the measurement data from the RI scanning means 100, and the hydraulic conductivity can be estimated. The degree of compaction can be estimated using the maximum dry density previously determined in a laboratory test and the dry density measured by the RI scanning means 100.

[0040] As described above, the degree of compaction and the permeability coefficient of the soil water-blocking layer are estimated as part of the RI scanning estimation process, and in this embodiment, a heat map 10 of the construction range of the soil water-blocking layer as shown in FIG. 6(b) can be output (step S103).

[0041] The heat map 10 shown in Figure 6(b) shows information on the estimated hydraulic conductivity of the soil water barrier layer, with the left side showing the heat map 10 when the scanning speed by the RI scanning means 100 is fast, and the right side showing the heat map 10 when the scanning speed by the RI scanning means 100 is slow. As shown in the figure, by slowing down the scanning speed, the grid spacing can be made finer, making it possible to estimate the hydraulic conductivity of each cell with high accuracy.

[0042] Next, in the RI scan evaluation step (step S104), it is determined whether the compaction degree and hydraulic conductivity of each cell estimated by the RI scan estimation step satisfy the RI scan quality standard. In this embodiment, the RI scan quality standard is set to a safe value of "specified value + 2% or more" for the compaction degree specified as the quality control standard. Furthermore, for the hydraulic conductivity, the RI scan quality standard is set to a safe value of "specified value - 2 orders or less" for the hydraulic conductivity specified as the quality control standard.

[0043] If the estimated degree of compaction and permeability coefficient both meet the above-mentioned RI scanning quality criteria, it is possible to proceed to the next process (such as the process of forming the next compacted layer or the process of laying the waterproof sheet).

[0044] On the other hand, if it is determined in the RI scan determination step (step S104) that either the estimated compaction degree or the permeability coefficient does not satisfy the RI scan quality standard, then a fixed RI estimation step is carried out in which the soil water barrier layer at the position corresponding to the relevant cell is measured using a fixed RI measurement device (step S105).The fixed RI measurement device can be a transmission type RI measurement device or a scattering type RI measurement device.

[0045] Then, after arithmetic processing of the measurement data, the degree of compaction and the hydraulic conductivity of the soil water impermeable layer are estimated again (step S106), and a determination is made in the fixed RI determination step (step S107) as to whether or not the fixed RI quality standard is met. In this embodiment, the fixed RI quality standard is a value on the safe side of the specified value of the degree of compaction established as the quality control standard, which is "a specified value + 1% or more." Furthermore, for the hydraulic conductivity, the fixed RI quality standard is a value on the safe side of the specified value of the hydraulic conductivity established as the quality control standard, which is "a specified value - 1 order or less."

[0046] If the degree of compaction and the coefficient of permeability measured by the fixed RI measuring means both meet the above-mentioned fixed RI quality standards, it is possible to proceed to the next process (such as the process of forming the next compacted layer or the process of laying the waterproof sheet).

[0047] On the other hand, if it is determined in the fixed RI determination step (step S107) that either the measured compaction degree or the hydraulic conductivity does not satisfy the fixed RI quality standard, a test hole type estimation step is performed in which a test is performed on the soil water barrier layer at a position corresponding to the relevant cell using a conventional quality control method (step S108).Conventional quality control methods that can be applied include the sand displacement method or the sand pounding method, which are performed by digging a test hole.

[0048] Then, in the test hole type determination step (step S109), it is determined whether the degree of compaction determined by the conventional quality control method satisfies the test hole type quality standard. In this embodiment, the specified value of the degree of compaction required for the soil water-blocking layer, which is determined as the quality control standard, is set as the test hole type quality standard value. If the degree of compaction determined by the conventional quality control method satisfies the test hole type quality standard, it is possible to proceed to the next step (such as the step of forming the next compacted layer or the step of laying the water-blocking sheet).

[0049] On the other hand, if it is determined in the test hole type determination step (step S109) that the obtained degree of compaction does not satisfy the test hole type quality standard, a re-construction step (step S110) is carried out in which the soil water shielding layer in the relevant area is re-compacted or the constructed layer is stripped away and re-construction is carried out. After re-compaction or re-construction, the degree of compaction is again confirmed using conventional quality control methods (step S108).

[0050] 4, the RI scanning determination process (step S104), the fixed RI determination process (step S107), and the test hole type determination process (step S109) are carried out in stages. However, the present invention is not limited to this. If it is determined in the RI scanning determination process (step S104) that the RI scanning quality standard is not met, a test hole type estimation process is carried out to estimate the degree of compaction using the sand replacement method or the sand pounding method, and the process may proceed to the test hole type determination process (step S109) to determine whether the test hole type quality standard is met.

[0051] With this configuration, the quality of the soil water shielding layer is screened area-wide through continuous mobile measurements by the RI scanning means, and if it is determined that it does not meet the RI scanning quality standards, the degree of compaction is judged using the sand replacement method or sand pounding method.The soil water shielding layer can then be re-compacted or stripped and re-constructed depending on the judgment results, making it possible to identify areas of poor construction and efficiently perform re-compaction or stripping and re-construction without unnecessary re-construction.

[0052] (Other embodiments, etc.) Although one embodiment of the quality control method for a soil water impermeable layer according to the present invention has been described above, the present invention is not necessarily limited to the above-described embodiment, and the following modifications are possible.

[0053] 8 shows an example of a mobile measurement mode using the RI scanning means 100. That is, it shows a mode in which mobile measurements are taken continuously in order from point A to point B, point C, and point D. In (1), the RI scanning means 100 performs mobile measurement from point A to point B, in (2), the RI scanning means 100 is moved backward, and in (3), the RI scanning means 100 is moved forward and positioned in the adjacent driving lane. Then, in (4), the RI scanning means 100 is moved backward to point C, which is the measurement start position, and in (5), the RI scanning means 100 performs mobile measurement from point C to point D.

[0054] When mobile measurements are continuously performed using the RI scanning means 100 in the above manner, the measurement data measured in (2) to (4) due to movement of the driving lane becomes complicated. In such cases, since each measurement data is linked to the position information from the GNSS receiver, it is possible to accurately estimate the compaction degree and permeability coefficient within the cell by averaging the measurement data within the same cell.

[0055] In the above-described embodiment, the quality control method for a soil water impermeable layer using bentonite-mixed soil as a water impermeable material has been described as an example. However, the quality control method for a soil water impermeable layer of the present invention is not necessarily limited to bentonite-mixed soil, and can also be effectively applied to, for example, a soil water impermeable layer using a natural clay-based water impermeable material or a cement-based soil water impermeable material.

[0056] In the above-described embodiment, the degree of compaction and the permeability coefficient of the soil water-blocking layer are determined in the RI scanning determination process (step S104) and the fixed RI determination process (step S107), but this is not necessarily limited to this mode, and either the degree of compaction or the permeability coefficient may be the subject of determination.

[0057] In the above-described embodiment, the allowable limits of the test hole quality standards are set to the specified values ​​required for the soil water-blocking layer, the allowable limits of the fixed RI quality standards are set to the safer side than the allowable limits of the test hole quality standards, and the allowable limits of the RI scanning quality standards are set to the safer side than the allowable limits of the fixed RI quality standards. In other words, the ranges for the lower limit of the compaction degree (%) and the upper limit of the permeability coefficient are set in stages to ensure the quality of the soil water-blocking layer. Here, the allowable limits for the specified values ​​in each quality standard are not necessarily limited to the numerical ranges described above, and the allowable ranges can be changed as appropriate.

[0058] In addition, in the above-described embodiment, the "degree of compaction" was estimated and determined as a quality control item, but this is not necessarily limited to this, and in order to manage the "degree of compaction," it is possible to use, in addition to the above-described "degree of compaction," "dry density," "void ratio," "wet density," etc. as quality standard control items.

[0059] Furthermore, in the above-described embodiment, the degree of compaction is estimated by moving around and measuring with the RI scanning means 100, but the measurement principle is not necessarily limited to RI, and the degree of compaction may be estimated using electromagnetic waves or elastic waves. In other words, it is also possible to measure the density by measuring the propagation speed of these waves, and to determine the degree of compaction of the soil water shielding layer.

[0060] In the above-described embodiment, the RI scanning means 100 is equipped with a laser measuring instrument 122, but this is not necessarily limited to a laser-based measuring instrument, and a measuring instrument based on other detection principles, such as ultrasound, may also be installed.

[0061] The scope of the present invention is defined by the claims rather than the description of the above embodiments, and includes all modifications within the meaning and scope of the claims. Furthermore, the specific materials, dimensions, shapes, etc. described in the above embodiments can be modified within the scope of solving the problems of the present invention. [Explanation of symbols]

[0062] 10. Heatmap 100 RI scanning means 102 Upper Frame 104 Column section 106 Wheels 108 axles 110 Lower frame 112 Auxiliary wheels 114 axles 116 bands 118 Source 120 detectors 122 Laser Measuring Instrument 124 Position detection unit 126 Management / Control Unit 1201 Density measurement section 1202 Moisture measurement unit

Claims

1. an RI scanning estimation step of estimating the degree of compaction and / or the permeability coefficient of the soil water impermeable layer by moving and measuring the RI scanning means within the construction range of the soil water impermeable layer; an RI scan evaluation step of determining whether the degree of compaction and / or the hydraulic conductivity obtained by the RI scan estimation step meets an RI scan quality standard; a fixed RI estimation step of estimating the degree of compaction and / or the hydraulic conductivity using a fixed RI measurement means when it is determined in the RI scan determination step that the RI scan quality standard is not satisfied; a fixed RI determination step of determining whether the degree of compaction and / or the hydraulic conductivity obtained by the fixed RI estimation step satisfies a fixed RI quality standard; In the fixed RI determination step, if it is determined that the fixed RI quality standard is not met, a test hole type estimation step of estimating the degree of compaction by a sand replacement method or a sand pounding method; A test hole type determination step for determining whether the degree of compaction obtained by the test hole type estimation step satisfies the test hole type quality standard, In the test hole type determination step, if it is determined that the test hole type quality standard is not met, the soil water impermeable layer is re-compacted or stripped and re-constructed. A quality control method for a soil water impermeable layer, comprising:

2. The allowable limit of the test hole type quality standard is a specified value required for the soil water barrier layer, and the allowable limit of the fixed RI quality standard is safer than the allowable limit of the test hole type quality standard, and the allowable limit of the RI scanning quality standard is safer than the allowable limit of the fixed RI quality standard. The quality control method for a soil water impermeable layer according to claim 1.

3. The RI scan estimation step comprises: a distance measuring step of measuring a distance between a measurement surface of the RI scanning means and a surface of the soil water impermeable layer; A correction step of correcting the estimated value of the degree of compaction and / or the hydraulic conductivity based on the separation distance measured in the separation distance measuring step. A quality control method for a soil water impermeable layer according to claim 1 or 2.

4. The RI scan estimation step comprises: and a heat map creation step of creating a heat map of the construction range of the soil water impermeable layer based on the estimated value of the degree of compaction and / or the permeability coefficient. The quality control method for a soil water impermeable layer according to claim 3.

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