JP2004020531A - Soil investigation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for achieving an exact subsurface environmental exploration by preventing any scout hole disruption without using muddy water. <P>SOLUTION: In the method, when inserting a core sampler for soil sampling into a scout hole to perform sampling of soil, an outer casing as a hollow cylindrical tool material is located outside the core sampler. This inhibits not only soil crash of scout hole wall surface but also contamination due to the soil crash, enabling more accurate sampling of soil sampling depth position. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Field of the Invention]
The present invention relates to a method for investigating soil, and more particularly to a method for sampling soil used for various tests such as soil and groundwater contamination investigation.
[0002]
[Prior art]
Until now, there is a possibility that the pollution of the environment including the soil may have a considerable effect on the human body. Therefore, it is required to investigate the situation of the environmental pollution and take appropriate measures. As a means for investigating soil contamination, soil contamination has been investigated by sampling soil at a predetermined position and analyzing contaminants contained therein.
The sampling of the soil consists of a hollow cylindrical body, usually called a core sampler, with one end open and the other end closed, and a gripper attached to the closed end. This is performed using a member. That is, this core sampler is pressed or driven into the soil at a predetermined position to be investigated, and the hollow inside the hollow cylindrical body of the core sampler is filled with the soil to be a sample. Remove the soil and collect the filled soil. This process is repeated a required number of times, and soil is collected up to a depth at which the investigation is required, and the soil is analyzed to investigate the vertical distribution of the substance to be detected. In this method, accurately grasping the vertical position where the analyzed soil was located is an extremely important factor for accurately determining soil contamination.
[0003]
By the way, when the core sampler is press-fitted or driven in to collect the soil further below the deep borehole by this method, the core sampler is pushed into the borehole while being in contact with the soil on the wall surface of the borehole. As a result, the wall of the soil collapses, and the collapsed soil accumulates on the bottom of the excavation hole. By the way, this sedimentary soil is taken into the core sampler that has reached the bottom of the excavation hole, and is perceived as if it existed at the bottom. For this reason, for example, if there is soil contaminated with a specific substance on the wall in the middle position, this contaminated soil is collapsed by the core sampler, and it is recognized that it exists at the bottom position, and the contamination site is determined. Will cause an error.
[0004]
Therefore, when investigating soil, when forming an inspection hole, a means for protecting a hole wall is employed.
[0005]
As one of the methods, in the ground environment survey, a method of excavating using bentonite mud to protect the hole wall is generally used. In recent years, from the viewpoint of environmental problems, an excavating method using as little bentonite mud as possible has been adopted. is there. For example, a so-called rotary percussion boring has been proposed as a technique capable of excavating even in fresh water by using a double pipe, and a technique using wire line sampling has been proposed as a method for sampling (core sampling) of the ground (geology). . In addition, core extraction by boring is generally performed using a wireline core barrel.
Conventionally, when performing a standard penetration test of soil (JIS A1219) and other in-situ tests, etc., after drilling, be sure to pull up the rod once, remove the drill bit (so-called core tube), and then perform the standard penetration test. A test device (otherwise, a current position test device, etc.) is attached, inserted into a drilled hole, and lowered to the bottom of the test hole for measurement.
[0006]
In the above-mentioned conventional ground environment survey, the following problems remain. In other words, the standard penetration test (JIS A1219) is frequently used for the purpose of evaluating the hardness and softness of the ground and sampling, but the measurement results fluctuate greatly due to collapse in the pores and the presence of residue at the bottom of the pores (slime). . Furthermore, in the case of a stratum having no cohesive component such as sandy soil or gravel soil, the load during the lifting of the pipe during the testing process (excavation with a bit, excavation of a drilling tool, and insertion of a standard penetration tester). There is also a problem of economics, such as the formation of the formation is easily loosened due to the pressure, and the work process becomes large due to the lifting time of these tools. In particular, recent drilling surveys require that various types of information be obtained from within the borehole, and various current position tests within the borehole (horizontal loading test inside the hole, cone penetration test, horizontal loading test, pore water pressure measurement, In-situ consolidation tests, vane tests, etc.) are generally performed, but all of these steps are complicated.
[0007]
Further, when the soil to be surveyed is clayey, water often stays in the upper layer due to poor water permeability. In order to investigate the status of pollutants dissolved in stagnant water in such a stratum, it is necessary to identify the depth position of this water. In order to penetrate into the inside, it was difficult to accurately grasp the depth position information.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems, and can prevent collapse of a survey hole without using muddy water, and prevent contamination due to contamination of soil mined from different depths, that is, contamination. It is another object of the present invention to provide a soil sampling method capable of accurately specifying the depth position of a collected soil sample.
[0009]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-mentioned problem, and press-fits a soil sampling member having a bottomed hollow columnar body having an opening at one end into a soil in a straight line or while rotating. Or, after the soil is filled into the internal cavity of the bottomed hollow columnar body, the soil in the investigation hole is excavated by pulling up the soil, and then the soil in the bottomed hollow columnar body is collected. In the soil survey method of collecting soil while drilling a survey hole consisting of a process,
A soil survey method characterized by disposing a hollow columnar member having both ends opened on the inner surface of a survey hole excavated by the soil collecting member to prevent the wall surface of the survey hole from collapsing.
[0010]
In the present invention, the bottomed hollow columnar portion of the soil collecting member is preferably a hollow cylinder or a hollow polygonal column. Further, in the present invention, it is preferable that the soil column-preventing hollow columnar member is a hollow cylindrical body having both ends opened.
[0011]
In the present invention, it is preferable that the press-fitting or driving of the soil collecting member is performed simultaneously with the insertion of the hollow columnar member for preventing soil collapse.
[0012]
According to the method of the present invention, the geology of the soil to be investigated can be applied irrespective of clay, sand or gravel, and even when groundwater is retained in the soil, water contamination It can be applied without causing contamination diffusion of the substance.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, members used in the present invention will be described in detail with reference to the drawings.
[0014]
(Soil sampling material: core sampler)
FIG. 1 shows a soil sampling member that can be used in the present invention. The soil collecting member 1 is connected to a hollow columnar soil collecting portion 1a having a structure in which one end is opened and the other end is opened by a small hole 1c, and an end opened by the small hole 1c. It has at least the structure provided with the grip part 1b. The small holes 1c are provided for dissipating air in the hollow portion of the core sampler when the core sampler is pressed or driven into the soil, thereby facilitating the pressing or driving. The fact that the longitudinal axis of the soil collecting section 1a and the longitudinal axis of the gripping section 1b coincide with each other allows the force applied to the gripping section 1b to be transmitted to the soil collecting section 1a without difficulty. Desirable. As the cross-sectional outer peripheral shape of the soil collecting portion 1a which is a hollow columnar body, a material having a shape such as a circle, an ellipse, or a polygon such as a square can be used. It is preferable to use a cylindrical body because a means for press-fitting while turning can be adopted as the insertion means.
[0015]
In addition, it is preferable that the soil sampling portion 1a, which is a hollow columnar body, has a shape that can be divided along the longitudinal direction, because it is easy to take out the sample soil from the soil sampling portion.
Examples of the material for the soil sampling member include iron and steel, stainless steel, aluminum alloy, bronze, and the like, and iron and steel are preferable because they are inexpensive and tough.
As such a soil sampling member, a member called a so-called core sampler generally used in soil survey can be used.
[0016]
(How to insert the soil sampling member into the soil)
The soil sampling member 1 applies pressure to the holding portion 1b at the upper portion thereof to press the core sampler into the soil, or applies a striking force to the holding portion 1b, and applies an impact to the holding portion 1b. May be press-fitted.
When the soil collecting part 1a of the soil collecting member 1 is a hollow cylindrical body, it is also possible to press-fit while rotating, and in this case, a motor (not shown) is attached to the holding part 1b of the soil collecting member 1. By connecting a rotary driving device such as described above and transferring it downward, the soil collecting member 1 can be pressed into the soil while turning.
A machine called a boring machine is suitable as a device driven by these means.
[0017]
(Hollow columnar member for preventing soil collapse: outer casing)
As a means for protecting the wall surface of the inspection hole into which the soil sampling member 1 is inserted, in the present invention, a hollow columnar member for preventing soil collapse is inserted into the inspection hole so as to be in close contact with the inner wall surface of the inspection hole.
Since the above-mentioned soil collecting member 1 freely passes through the inside of this hollow columnar member for preventing soil collapse, the shape of the hollow columnar member for preventing soil collapse, the so-called outer casing, has It is preferable that the outer surface of the soil sampling member and the inner surface of the hollow columnar member for preventing soil collapse are so close as not to hinder the movement of the soil sampling member 1 passing therethrough, and to the extent that there is no room for soil to remain. Therefore, it is preferable that the inner shape of the hollow columnar member for preventing soil collapse is similar to the cross-sectional shape of the soil sampling member. The cross-sectional shape may be any of a cylindrical shape and a polygonal shape. However, it is possible to insert by inserting a core sampler that is inserted, it is easy to manufacture, and it is necessary for the hollow columnar member for preventing soil collapse. The circular shape is most preferable because the force against the external pressure is maximized.
Examples of the material of the hollow columnar member for preventing soil collapse include a steel material, stainless steel, an aluminum alloy, and bronze, and a steel material is preferable because it is inexpensive and has a high toughness.
In addition, the inner diameter of the soil collapsible hollow columnar member has an inner diameter that is several mm to several cm larger than the outer diameter of the soil sampling member because of the ease of insertion and the ease of sampling. Often.
[0018]
(Insertion of a hollow columnar member for preventing soil collapse into the soil)
When inserting the hollow columnar member for preventing soil collapse into the soil, it is preferable that the hole wall of the inspection hole is broken or collapsed as much as possible. As a method therefor, a method of press-fitting while directly rotating from directly above the investigation hole, a method of directly press-fitting into the investigation hole using a machine or the like without rotating, or a method of hitting from the top may be used. Depending on the quality of the soil (clay, gravel, etc.), any method of insertion into the soil can be used.
[0019]
Hereinafter, embodiments of the investigation method of the present invention will be described.
[0020]
[First Embodiment of the Invention]
The first embodiment of the present invention will be described with reference to FIG. 2 which is a process chart for explaining this method.
First, a core sampler 1, which is a soil sampling member, is driven into the underground 2 at a point to be investigated (FIG. 2A). At this time, the soil 5 serving as a sample is filled in the space of the soil sampling part 1a which is the hollow columnar body with the bottom of the core sampler. Subsequently, when the core sampler 1 is pulled out of the soil (FIG. 1 (b)), the soil sample 5 is pulled up while being held by the core sampler 1, and is taken out from the soil sampling part 1a of the core sampler 1, The analysis is performed by a predetermined method. Subsequently, the core sampler 1 is driven into the soil to collect the soil at a deeper position, but before that, the outer casing 4 is driven into the wall surface of the inspection hole to prevent the wall surface of the inspection hole 3 from collapsing. . At this time, the wall surface is shaved due to the contact between the outer casing 4 and the wall surface of the inspection hole, and slightly collapsed soil 6 called slime is deposited on the bottom of the inspection hole (FIG. 1C). Then, the wall-falling soil 6 at the bottom of the inspection hole is removed by using the soil removing member 7 (FIG. 1D). Next, the core sampler 1 is further driven in (FIG. 1 (e)), and the sampling of the soil at a deeper position is continued.
According to such a method, it is possible to perform sampling of soil without a risk of contamination without mixing inaccurate soil with position information having different depth positions in the collected sample soil.
[0021]
When the method of the present embodiment is applied to a geological layer in which groundwater is stagnant, at the stage where the core sampler is removed, groundwater flows into the investigation hole, but after inserting the outer casing, the groundwater is removed by a pump. Removal is preferred.
[0022]
[Embodiment of second invention]
Next, an embodiment of the present invention having a different sampling procedure will be described with reference to FIG.
In this method, as shown in FIG. 3, the core sampler 1 and the outer casing 4 are driven simultaneously. First, as shown in FIG. 3 (a), the core sampler 1 and the outer casing 4 are fixed to each other so that their bottoms substantially coincide with each other, and this is pressed into the ground by means of press-fitting or driving. Type 2. Next, only the core sampler 1 in which the soil sampling section 1a is filled with the sample soil is pulled up to the ground (FIG. 3B), and the sample soil 5 is taken out from the core sampler 1, and further, the second outer casing is formed. 4 'and the core sampler 1 are fixed and inserted into the previously formed inspection hole 3 (FIG. 3 (c)). At this time, the outer casing disposed earlier is pressed and pressed into the soil as the core sampler 1 and the second outer casing 4 ′ are inserted into the soil. Prevent it from collapsing. According to this method, in addition to the effects obtained in the first embodiment of the present invention, when the outer casing is inserted into the inspection hole as compared with the method of the first embodiment of the present invention, Since it is possible to prevent the collapsed wall soil, the step of removing the wall collapsed soil is not required, and the operation process can be simplified.
[0023]
An example of an outer casing suitable for use in this method is shown in FIG. As shown in FIG. 4, the bottom of the outer casing 4 is bent inward to cover the bottom of the soil sampling unit 1 a of the core sampler 1.
If the soil enters the gap between the core sampler 1 and the outer casing 4 when the core sampler 1 and the outer casing 4 are inserted into the ground, when the core sampler 1 from which the sample soil has been collected is pulled up, the outer casing is removed. Not only is it difficult to pull up the core sampler 1 with the 4 remaining, but also the outer casing 4 or the core sampler 1 is deformed or destroyed. However, with the above-described configuration, when the core sampler 1 and the outer casing 4 are inserted into the ground, soil is prevented from entering the gap between the core sampler 1 and the outer casing 4, and the core sampler 1 1 or the outer casing 4 can be prevented from being deformed or broken.
[0024]
According to the method of the present embodiment, the outer casing 4 is also inserted into the soil at the same time as the core sampler 1 is inserted even in the geological layer where the groundwater is retained, so that even when the groundwater is retained in the soil. In addition, the groundwater accumulates in the investigation hole, and the investigation hole can be drilled without causing the diffusion of the pollutants dissolved in the groundwater.
[0025]
[Third Embodiment of the Invention]
As another sampling procedure, FIG. 5 shows an example in which the outer casing 4 is driven before excavating a survey hole in the ground.
As shown in FIG. 5, the outer casing 4 is first driven into the underground 2 (FIG. 5A). At this time, the soil 3 serving as a sample is held at the position serving as the inspection hole without changing the position. Next, the core sampler 1 is inserted into the outer casing 4, and the sample soil 5 is taken into the core sampler 1 (FIG. 5B). Next, the core sampler 1 is pulled up, and the sample soil 5 is taken out (FIG. 5C). Then, the second outer casing 4 'is disposed on the outer casing 4, and the second outer casing 4' is inserted to insert the outer casing 4 buried earlier into a deeper position (FIG. 5D). . Then, the step of inserting the core sampler 1 further into the inspection hole 3 and collecting the sample soil is repeated to a required depth. Thus, it is possible to collect the sample soil at the correct collection position without generating the wall collapsed soil.
[0026]
[Embodiment of Fourth Invention]
Yet another sampling procedure is shown in FIG.
As shown in FIG. 6, first, the core sampler 1 is inserted into the position to be investigated (FIG. 6A). Next, the outer casing 4 is driven around the core sampler 1 to a position substantially equal to the bottom of the core sampler 1 without removing it (FIG. 6B). Next, the core sampler 1 filled with the sample soil 5 is pulled out (FIG. 6C), and the sample soil 5 is taken out. Next, the core sampler 1 is inserted into a deeper position of the inspection hole 3 after taking out the sample soil 5, the sample soil is taken in (FIG. 6 (d)), and the second outer casing is driven around the sample soil. By repeating this step, a sample soil can be collected.
According to this method, an accurate sample soil at a sampling position can be collected without generating the collapsed wall soil.
[0027]
[Modification]
In the above embodiments of the present invention, an example in which the core sampler is used as the soil collecting member, and the outer casing is used as the hollow columnar body for preventing soil collapse, but a member having a shape other than these is also applicable. Any member exhibiting a function equivalent to the above function can be used in the present invention. Also, the order of inserting the core sampler and the outer casing into the soil can be performed by combining the procedures described in the above embodiment. For example, after inserting the core sampler, inserting the outer casing, and then removing the core sampler, the core sampler and the second outer casing can be inserted simultaneously.
[0028]
【Example】
(Example 1)
An embodiment of the present invention will be described with reference to FIG.
A core sampler 1 having an outer diameter of 8.6 cm was inserted using a boring machine to a depth of 1 m in a range to be an inspection hole, and pulled up (a) and (b). Next, an outer casing 4 having an inner diameter of 9.6 cm and a thickness of 5 mm was inserted using a boring machine to the same depth where the core sampler 1 was inserted (c). Further, the tool 7 for removing accumulated soil was inserted using a boring machine to the same depth where the outer casing 4 was inserted (d), and the remaining wall-falling soil 6 was removed by the tool 7 (e). Next, the core sampler 1 was inserted to a depth of 2 m using a boring machine, and only the core sampler 1 was pulled out upward. In this order, soil was collected to a depth of 3 m.
A simple analysis of heavy metals was performed on the sample soil collected by the above method. As a result, heavy metals were detected from the surface and the central part (0.5 m, 1 m and 1.5 m depth) in the soil collected by the first sampling, but the depth was 2 m, 2.5 m and Heavy metals were not detected from the 3 m soil. Therefore, according to the sampling method of the present embodiment, it can be seen that there was no contamination due to the soil collapsed on the wall.
[0029]
(Comparative Example 1)
Hereinafter, a soil survey method according to a comparative example will be described. The same core sampler 1 as that used in Example 1 was inserted into the ground at a sampling position located in the vicinity of Example 1 using a boring machine to a depth of 1 m, then pulled up, and collected. The soil was removed from the core sampler. Next, the core sampler was further inserted to a depth of 2 m using a boring machine, and this was lifted. In this order, soil was collected to a depth of 3 m.
As a result of performing a simple analysis for detecting heavy metals on the collected soil, heavy metals were detected from any of the surface layer, 0.5 m, 1 m, 1.5 m, and 2.5 m soil. In Example 1, since no heavy metals are contained in the ground having a depth of 2 m to 3 m, the method of this comparative example has a depth of 0 m to 1 m. It is determined that the heavy metals contained in the soil in the range of m are mixed into the soil collected at a depth of 2.5 m to cause contamination.
[0030]
(Example 2)
Another embodiment of the present invention will be described with reference to FIG.
The same core sampler 1 and outer casing 4 as those used in Example 1 were simultaneously inserted into a position to be an inspection hole to a depth of 1 m using a boring machine (a). Next, only the core sampler 1 was pulled out upward (b). Further, the core sampler 1 and the second outer casing 4 ′ were inserted further deeply into a depth of 2 m using a boring machine, and only the core sampler 1 was pulled out. In this way, the ship dug to a depth of 3 m.
As a result, when the soil at the time of the second sampling was confirmed, the soil was different from the soil sampled at the first time at a depth of 2.7 to 2.0 m, and the outer casing was used. It was determined that contamination could be prevented.
[0031]
(Example 3)
Another embodiment according to the present invention will be described with reference to FIG.
An outer casing 4 having an inner diameter of 11.3 cm, a thickness of 6 mm, a tip angle of 45 degrees, and an outer diameter of the tip of 12.5 cm is sunk into the ground at a position to be a survey hole to a depth of 1 m using a boring machine. Inserted (a). Next, a core sampler 1 having an outer diameter of 8.6 cm was inserted into the outer casing 4 to a depth equal to that of the outer casing 4 using a boring machine (b), and thereafter, only the core sampler was pulled out upward (c). Further, only the second outer casing was inserted to a depth of 2 m using a boring machine (d), and a core sampler was inserted to a similar depth using a boring machine and pulled out to the upper part. In this way, the ship dug to a depth of 3 m.
As a result, when the soil at the time of the second sampling was confirmed, the soil quality was different from the soil sampled at the first time at a depth of 2.0 to 2.7 m, and the outer casing was used. It was determined that contamination could be prevented.
[0032]
(Example 4)
Another embodiment according to the present invention will be described with reference to FIG.
A core sampler 1 having an outer diameter of 8.6 cm is inserted using a boring machine to a depth of 1 m using a boring machine (a), and then an inner diameter of 11.3 cm, a thickness of 6 mm, a tip angle of 45 degrees, and a tip part of An outer casing 4 having an outer diameter of 12.5 cm was inserted outside the core sampler 1 using a boring machine (b). Next, only the core sampler was pulled out upward (c), and the sample soil was collected. Further, only the core sampler 1 was inserted to a depth of 2 m using a boring machine, and the second outer casing was inserted outside the core sampler 1. Only the core sampler was pulled out again to confirm the soil quality of the sample. In this way, the ship dug to a depth of 3 m.
As a result, it was determined that the soil was different at the depth of 2.0 to 2.7 m from the soil sampled for the first time, and that contamination by the collapsed soil on the wall could be prevented by using the outer casing.
[0033]
【The invention's effect】
According to the present invention, the following effects can be obtained.
By using a cylindrical outer casing outside the sampling device according to the present invention, contamination such as collapse in the hole and residue at the bottom of the hole can be prevented, and accurate soil sampling can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a soil sampling member of the present invention.
FIG. 2 is a process diagram of a soil survey method showing an example of the present invention.
FIG. 3 is a process chart of a soil survey method showing another embodiment of the present invention.
FIG. 4 is a partial schematic cross-sectional view of a hollow columnar member for preventing soil collapse and a soil sampling member used in the present invention.
FIG. 5 is a process chart of a soil survey method showing another embodiment of the present invention.
FIG. 6 is a process chart of a soil survey method showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Core sampler 2 ... Soil 3 ... Survey hole 4 ... Outer casing 5 ... Sample soil 6 ... Wall collapsed soil (slime)
7 ... Removal tool

Claims (4)

A soil sampling member having a bottomed hollow columnar portion having an opening at one end is press-fitted or driven into the soil in a straight or swirling direction into the soil, and is inserted into the internal cavity of the bottomed hollow columnar body. After filling the soil, after digging the soil in the investigation hole by pulling it up, in a soil survey method of collecting soil while digging a survey hole consisting of a step of collecting soil in the bottomed hollow columnar body,
A soil survey method comprising: disposing a hollow columnar member having both ends open at the inner surface of a survey hole excavated by the soil collecting member to prevent the wall surface of the survey hole from collapsing. The soil survey method according to claim 1, wherein the bottomed hollow columnar portion of the soil sampling member is a hollow cylinder or a hollow polygonal column. The soil investigation method according to claim 1 or 2, wherein the hollow columnar member for preventing soil collapse is a hollow cylindrical body having both ends opened. The soil survey method according to claim 1, wherein the press-fitting or driving of the soil collecting member is performed simultaneously with the insertion of the hollow columnar member for preventing soil collapse.

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