JP5864075B2 - Construction method of low water-permeable impermeable structure - Google Patents

Description

  The present invention relates to a low-permeability natural clay mineral crushed stone material and its density used in places where water must be permanently blocked, such as river blankets, paddy fields, reservoirs, water-blocking structures at disposal sites, or ruins overcover bases. It relates to a measurement method.

  For example, in recent years, there has been a strong demand for preventing leakage of leachate from a waste disposal site. In particular, in Japan, most of the disposal sites are located inland and in the mountains, and leakage of leachate causes contamination of drinking water sources and groundwater. The structural standards related to this are strengthened and a double water-impervious system is required.

  In any of the currently used water-blocking structures, a water-blocking sheet is used in any structure, but as a water-blocking sheet that has recently attracted attention, a geosynthetic clay liner (GCL) with a composite structure of bentonite and a plastic material. It has been known. Various types of GCL have been proposed, such as products in which bentonite is sandwiched between non-woven fabrics or woven fabrics, and products in which bentonite is bonded to plastic sheets, which complements the concerns about sheet damage and durability caused by synthetic polymers and rubber. When GCL is used for the purpose of water-blocking the bottom of the disposal site, leakage of leachate is prevented by the high water-blocking performance of the swollen bentonite, and when the sheet breaks and has holes. It has been demonstrated to be sealed by the self-healing action of bentonite. In this way, waste disposal sites are expected to have clay, especially bentonite swelling / seal function, water stop function, and long-term stability.

  Further, as this type of conventional water shielding material, bentonite mixed soil and asphalt pavement as shown in Patent Document 1 are also known.

Japanese Patent No. 4036975

  However, the conventional GCL is a thin sheet with a thickness of several millimeters, and has a problem that the function deteriorates due to slight unevenness and erosion, and water leakage due to twisting of the joint portion of the sheet occurs. In addition, there was a problem that water could permeate at an early stage in a place where water is always accumulated such as a pond.

  In addition, in the case of bentonite mixed soil, the quality may vary due to the inability to mix uniformly depending on the raw material soil, and quality control such as methylene blue adsorption test and funnel viscosity test is complicated and there is a problem in accuracy when mixing. It was. Furthermore, when the locally generated soil is used as raw material soil, there are many uncertainties in the setting of the compaction density because of the various physical properties due to the generated soil, and the measurement results are not reliable. This compaction density is measured using the RI test, but since the hole is forced to be formed in the water-shielding layer because it is measured by inserting a source rod, there is a problem that the layer is temporarily destroyed and the uniformity is impaired. Was.

  In addition, conventional asphalt pavement has a problem that it easily deteriorates and has a high water permeability coefficient. Since it was necessary to ask a contractor, the construction cost was high.

  The present invention was devised in view of the current situation, and the object of the present invention is to provide a low-permeability natural clay mineral crushed stone material that can be permanently water-blocked, uniform in quality, and inexpensive, and a density measuring method thereof. It is something to try.

In order to achieve the above object, the low water permeability natural clay mineral crushed stone material according to the present invention is a natural clay material containing smectite having a particle size of 25 mm or less, and the natural water content ratio is the upper limit of the optimum water content ratio. value and then adjusted within -10% optimum water content ratio is lower limit, is characterized in that it has a less permeable water coefficient number 1 × ¹⁰ -8 cm / sec.

In the present invention, the water content ratio is an optimal water content ratio− 10% lower limit value ≦ W ≦ optimal water content upper limit value.

  Furthermore, in the method for measuring the density of the low-permeability natural clay mineral crushed stone material according to the present invention, the density of crushed stone having a particle size of 25 mm or less is measured with a simple bearing capacity measuring device (Caspol). It is characterized by doing.

  Therefore, in the low water permeability natural clay mineral crushed stone material according to the present invention, water can be permanently blocked and the quality can be provided uniformly. Moreover, since it is not necessary to dry like the conventional water-impervious clay material, it can be provided at a low cost. Furthermore, since it is not completely dried, compaction is easy and water-blocking construction is facilitated.

In the present invention, since the water content ratio is set to the optimum water content ratio− 10% lower limit value ≦ W ≦ optimal water content upper limit value, the overcapping of the waste disposal site can be more optimally configured.

Further, in the present invention, the low permeability geosynthetic clay Oite in density to measure the mineral crushed stone material, the density of the particle size 25mm following lithotripsy natural clay material including smectite, simple supporting force measuring device (Caspol) can be measured easily and quickly.

  Hereinafter, the present invention will be described in detail based on one embodiment shown in the accompanying drawings.

  FIG. 1 is a schematic cross-sectional view showing a first water-impervious structure of a waste treatment plant using a low-permeability natural clay mineral crushed stone material according to the present invention, and FIG. 2 shows a configuration of a simple bearing capacity measuring device (Caspol). FIG. 3 is a graph showing a moisture content ratio / impact acceleration calibration curve, and FIG. 4 is a second water-impervious structure of a waste treatment plant using a low-permeability natural clay mineral crushed stone material according to the present invention. FIG. 5 is a schematic cross-sectional view, and FIG. 5 is a schematic cross-sectional view showing an example of an overcapping structure of a waste disposal site.

  In the first water-impervious structure shown in FIG. 1, reference numeral 1 in the figure indicates a low-permeability natural clay mineral crushed stone material according to the present invention, 2 is a known water-impervious sheet, 3 is protective soil, and 4 is waste. Each is shown.

ｃｍ／ｓｅｃ以下に調整されている。なお、この発明に係る天然粘土は、カルシウム型やナトリウム型に適用することができるが、特に、海水に強いカルシウム型に有効である。 The low-permeability natural clay mineral crushed stone material according to the present invention is a natural clay material containing smectite having a particle size of 25 mm or less, and the natural water content is adjusted to the optimum water content upper limit value and the lower limit value is adjusted to within -10%. , Or adjusted water content ratio

It is adjusted to cm / sec or less. The natural clay according to the present invention can be applied to the calcium type and the sodium type, but is particularly effective for the calcium type resistant to seawater.

  The first water-impervious structure is first prepared after leveling the water-permeable base, and then, for example, a low-permeability natural clay mineral crushed stone 1 is uniformly laid with a thickness of 10 cm, and then the simplified bearing capacity measuring device (Cathpol) shown in FIG. ) Rolling while measuring at 10, and then laying the water-impervious sheet 2 with t = 1.5 as a guide, and then laying the protective soil 3 with a thickness of 50 cm or more on it.

ｃｍ／ｓｅｃ以下の性能を確保することができる。 In this first water-impervious structure, even if the water-impervious sheet 2 is damaged, water leakage can be prevented in advance, and it is easy to keep the water-impervious performance uniform. Moreover, since it is not completely dry, it can be provided at a low cost, and further, compaction is easy and water shielding construction is also facilitated. That is, in this embodiment, the water content ratio is defined as 25 mm or less and easy to compact. Therefore, workability is improved, and the hydraulic conductivity is determined by the degree of compaction with a maximum dry density of 90% or more.

The performance of cm / sec or less can be ensured.

  FIG. 2 shows a simple support force measuring device (Caspol) 10. In FIG. 2, reference numeral 11 denotes a rammer with an accelerometer built therein, 12 a tripod, 13 a display, 14 a connector, 15 Indicates a switch lever, 16 indicates a handle, and 17 indicates a ground surface. Since the configuration, operation, and effect of each part are known, detailed description thereof will be omitted here.

  In the quality control method for measuring density with this simple bearing capacity measuring instrument (Caspol) 10, the specified value of Casbol is determined from the pre-prepared moisture content / impact acceleration calibration curve shown in FIG. It can be managed by measuring whether it is equal to or greater than the degree (maximum dry density 90%) Ia value, can be measured non-destructively in a few seconds, and can be managed in a plane.

ｃｍ／ｓｅｃである天然粘土鉱物、かつ作業可能強度コーン指数ｑｃ≧１，５００ＫＮ／ｍ２の条件時、含水比範囲は２３〜３０％であり、作業可能なキャスポル測定範囲９≦Ｉａ値≦１５．８とすることで、締め固め度を簡易なキャスボル１０で面的に迅速に測定することができる。天然粘土は、含水比が多すぎると材料に粘性が増し作業性が著しく低下するが、この発明に係る低透水性天然粘土鉱物砕石１はこのようなことがない。また、従来の測定に使用されているＲＩ試験器と比較し、測定時間が１／６０以下で特殊なキャリブレーションも不要である。即ち、この発明に係る測定方法にあっては、測定時間が短時間であるため、従来の測定方法に比べて信頼性が大幅に向上する、という効果が得られる。 When performing compaction quality control, for example, the hydraulic conductivity k = preliminarily when the compaction prescribed value p = max 90% ≧ 1.083 g / cm 2.

When the natural clay mineral is cm / sec and the workable strength corn index qc ≧ 1,500 KN / m 2, the water content ratio range is 23 to 30%, and the workable Caspol measurement range 9 ≦ Ia value ≦ 15. By setting it to 8, the degree of compaction can be quickly measured by a simple casbol 10 in a plane. If the natural clay has too much water content, the viscosity of the material increases and the workability is remarkably lowered. However, the low water permeability natural clay mineral crushed stone 1 according to the present invention does not have such a problem. In addition, the measurement time is 1/60 or less and no special calibration is required as compared with the RI tester used in the conventional measurement. That is, in the measurement method according to the present invention, since the measurement time is short, the effect that the reliability is significantly improved as compared with the conventional measurement method is obtained.

  In the 2nd water-impervious structure shown in FIG. 4, the code | symbol 1 in a figure is the low water permeability natural clay mineral crushed stone material which concerns on this invention, 2A is a well-known anti-suction mat | matte, 3A is a vegetation base, 4 is waste. Other than those shown, the other configurations and functions are the same as those used in the first person water structure. Is omitted here.

  In this second water-impervious structure, since the waste 4 does not come into contact with rainwater, a leachable water facility becomes unnecessary, the waste 4 can be stably covered, and when applied to a paddy field Can store water permanently. Furthermore, moisture is guided to the uniform low water-permeable clay 1 by the suction preventing mat 2A, and erosion can be prevented.

ｃｍ／ｓｅｃ）２２で覆い、この高品質粘土２２の上部を吸出し防止マット２３で覆い、この吸出し防止マット２３の上層を厚さ３０ｃｍ以上の排水層２４で覆い、この排水層２４の上部を厚さ６０ｃｍ以上の覆土２５で覆った構造例を示している。尚、上記高品質粘土の透水係数は、最大乾燥密度９０％値時のものである。 FIG. 5 shows an example of a structure in which the waste disposal site is overcapped. The upper part of the waste ground surface covering soil 20 is covered with a degassing layer 21 as necessary, and the upper part of the degassing layer 21 is an example of this embodiment. High quality clay (d = 5cm hydraulic conductivity k =

cm / sec) 22, the upper part of the high-quality clay 22 is covered with a suction prevention mat 23, the upper layer of the suction prevention mat 23 is covered with a drainage layer 24 having a thickness of 30 cm or more, and the upper part of the drainage layer 24 is thick. The example of a structure covered with the covering soil 25 of 60 cm or more is shown. The water permeability coefficient of the high quality clay is that at the maximum dry density of 90%.

It is a cross-sectional schematic diagram which shows the 1st water-impervious structure of the waste disposal site using the low water-permeable natural clay mineral crushed stone material which concerns on one example of this invention. It is a front view which shows the structure of the simple supporting force measuring device (caspol) used for this invention. It is a graph which shows the moisture content and impact acceleration calibration curve of the low water permeability natural clay mineral crushed stone concerning one example of this invention. It is a cross-sectional schematic diagram which shows the 2nd water-impervious structure of the waste disposal site using the low water-permeable natural clay mineral crushed stone material which concerns on one example of this invention. It is a cross-sectional schematic diagram which shows the structural example which overcapped the refuse disposal site.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low-permeability natural clay mineral crushed stone material 2 Water shielding sheet 2A Suction prevention mat 3 Protective soil 3A Vegetation base 4 Waste 10 Simple bearing capacity measuring device (Caspol)
20 Waste soil surface covering soil 21 Gas vent layer 22 High quality clay 23 Anti-suction mat 24 Drainage layer 25 Covering soil

Claims (1)

A natural clay material containing smectite whose natural water content is the optimum water content upper limit and the lower limit is within the optimum water content -10%, and a natural clay mineral crushed stone material adjusted by pulverizing the particle size to 25 mm or less A method for constructing a low water-permeability impermeable structure having a water permeability of 1 × 10 ⁻⁸ cm / sec or less , characterized in that it is laid and compacted on a water-permeable base without going through a drying step .

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