JP5937924B2 - Ground density estimation method, ground landfill management method using this ground density estimation method, ground compaction management method, and caisson filling management method - Google Patents

Description

  The present invention relates to a method for estimating the density of ground based on the results of a cone penetration test, a method for managing land reclamation using the ground density estimating method, a method for managing ground compaction, and a method for managing caisson filling.

  Conventionally, as part of ground investigation, for example, ground density is measured in order to ascertain whether a predetermined ground density has been achieved, for example, in landfill ground or compacted ground. As a method for measuring the ground density, there are known a density measurement by an RI cone penetration test using γ (gamma) rays emitted from a radioisotope (RI) and a method of directly measuring the density by sampling a sample that is not disturbed. Yes.

  The RI cone penetration test requires background gamma ray intensity when measuring density. Therefore, it is necessary to first insert the three-component cone into the ground, measure the background gamma ray intensity, extract the three-component cone, install the RI cone, and insert it again to measure the gamma ray intensity.

  Patent Document 1 discloses a ground density measuring device that measures the acceleration at a time when a cone with a weight is dropped and penetrates into the ground, analyzes the acceleration, and measures the density of the ground.

JP-A-11-241332

"Ground Survey Method and Explanation" (published by the Geotechnical Society)

The RI cone penetration test uses a radioisotope compared to the normal cone penetration test, making it difficult to handle the equipment, and the measurable density is up to 2.3 Mg / m ³ . In the RI cone penetration test, the density of the ground is calculated from the measurement result of gamma ray intensity. However, when measuring materials other than soil that have a gamma ray shielding effect, the density measurement accuracy deteriorates. . In general, it is known that a material having a high specific gravity such as lead, iron, or concrete has an effect of shielding gamma rays. For example, density measurement of the ground composed of steel slag or the like is likely to involve an error.

  In addition, sampling for measuring the ground density has a problem that it is not possible to simply sample a sample that is not disturbed, and costs are high. Cited Document 1 makes it possible to set the falling height of a cone with a weight accurately and in a very short time, and does not solve such a problem.

  In view of the problems of the prior art as described above, the present invention is not a RI cone penetration test, which is difficult to handle the equipment, and it is based on the cone penetration test without sampling for measuring the ground density. An object of the present invention is to provide a ground density estimation method capable of estimating the density, a ground landfill management method, a ground compaction management method, and a caisson filling management method using the ground density estimation method.

  In order to achieve the above object, the ground density estimation method according to the present embodiment includes a step of measuring a tip resistance by a cone penetration test at an original position, which is a ground density measurement target, a step of assuming a ground density, The step of calculating relative density based on the measured tip resistance and the assumed ground density, and the soil density is calculated based on the results of the minimum and maximum soil density tests obtained in advance and the calculated relative density. Comparing the assumed ground density with the calculated ground density, and if both are not equal, returning to the ground density assuming step and changing the assumed ground density, the relative density calculating step and the ground Performing a density calculation step and, if equal, determining the ground density as a ground density estimate.

  According to this ground density estimation method, the cone penetration test is performed in situ without using difficult measuring instruments such as the RI cone penetration test and without sampling for the measurement of ground density. It is possible to calculate and easily estimate the ground density. Moreover, the density of granular material other than soil can be measured without sampling for measuring the ground density. Further, any place where the cone of the cone penetration test can penetrate into the ground and the tip resistance can be measured is applicable, and the applicable range is extremely wide.

  In the ground density estimation method, it is preferable that the tip resistance is measured at a plurality of points in the depth direction by the cone penetration test, and the depth position for calculating the ground density is changed from the surface layer of the ground to the depth direction. Thereby, the data of shallower depth can be used for the calculation of the deeper ground density, and the depth direction distribution of the ground density can be estimated.

  Moreover, it is preferable to obtain | require previously the relationship between the said tip resistance corresponding to the soil to measure, the said relative density, and the said ground density (or vertical effective stress).

  The land reclamation management method according to the present embodiment includes a step of throwing earth and sand into a landfill target site, a step of compacting a soil region formed by throwing the earth and sand, and the compacted soil region Performing the above-described ground density estimation method for estimating the ground density, and determining whether the ground density is an appropriate value based on the estimated ground density, If the ground density is not an appropriate value, the process returns to the compacting step.

  According to this landfill management method, the ground density can be easily estimated by performing the above-described ground density estimation method for the compacted soil region, so that a reasonable value, for example, a predetermined ground density is achieved. It is possible to grasp whether or not it is made, and it is possible to efficiently manage landfill construction.

  The ground compaction management method according to the present embodiment includes a step of compacting the ground to be compacted, and a step of estimating the ground density by performing the above-described ground density estimation method for the compacted ground. And determining whether the ground density is a reasonable value based on the estimated ground density, and if the ground density is not a reasonable value, returning to the compacting step Features.

  According to this ground compaction management method, the ground density can be easily estimated by performing the above-described ground density estimation method for the compacted ground, so that an appropriate value, for example, a predetermined ground density can be achieved. It is possible to grasp whether or not the ground is compacted, and to efficiently manage the compaction work of the ground.

  The management method of caisson filling according to the present embodiment includes a step of throwing the filling material into the caisson, a step of compacting the filling material region formed by the filling of the filling material, and the compaction. Performing the above-described ground density estimation method for the filling material region and estimating the ground density, and determining whether the ground density is an appropriate value based on the estimated ground density And when the ground density is not an appropriate value, the process returns to the compacting step.

  According to this management method for caisson filling, the filling material region formed by compacting the filling material such as soil and sand into the caisson installed at the bottom of the water and compacted by the filling material is described above. Since the density of the filling material can be easily estimated by implementing the ground density estimation method, it is possible to grasp whether a reasonable value, for example, a predetermined density has been achieved, and The input construction can be managed efficiently.

  According to the ground density estimation method of the present invention, the ground can be measured based on the cone penetration test without performing the RI cone penetration test, which is difficult to handle the equipment, and without sampling for measuring the ground density. Can be easily estimated.

  According to the land reclamation management method of the present invention, it is possible to grasp whether or not the ground density is an appropriate value in the compacted soil region, and efficiently manage the land reclamation construction. can do.

  According to the ground compaction management method of the present invention, it is possible to grasp whether or not the ground density is an appropriate value in the compacted ground, and efficiently manage the construction of the ground compaction. be able to.

  According to the caisson filling method of the present invention, it is possible to grasp whether or not the ground density is an appropriate value in the compacted filling material region, and the caisson filling is efficiently performed. Can be managed.

It is a flowchart for demonstrating step S01-S06 of the ground density estimation method by this embodiment. It is the schematic which shows the example of the test apparatus of the static cone penetration test implemented in the estimation method of the ground density of FIG. It is a flowchart for demonstrating step S11-S14 of the landfill management method using the ground density estimation method of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining steps S01 to S06 of the ground density estimation method according to this embodiment. FIG. 2 is a schematic view showing an example of a test apparatus for a static cone penetration test performed in the ground density estimation method of FIG.

  The ground density estimation method according to the present embodiment estimates the ground density based on the preliminary soil test results and the static cone penetration test results.

First, a static cone penetration test apparatus will be described with reference to FIG. The static cone penetration test apparatus 10 includes a penetration apparatus 11 that allows a cone 14 attached to the tip of a rod 13 to penetrate the ground G at a constant speed by hydraulic pressure, and the like. The penetration apparatus 11 is fixed and placed on the ground surface S. The fixed portion 12 fixed by the anchor 17 in G, the depth measuring device 15 for measuring the penetration depth of the cone 14, and the electrical signals from the cone 14 and the depth measuring device 15 are inputted to measure various data. And a measuring device 16 for storing. The cone 14 is made of, for example, steel and has a tip angle of 60 degrees and a bottom area of 1000 mm ² .

  The static cone penetration test apparatus 10 can be configured, for example, as a three-component cone electric type that measures three components of cone tip resistance, circumferential friction, and pore water pressure. The test apparatus 10 of FIG. 2 is an example, and it is needless to say that other configurations may be used.

  Each step S01 to S06 of the ground density estimation method according to the present embodiment will be described with reference to FIGS.

  The tip resistance qc of the cone 14 is measured by the measuring device 16 while the cone 14 is penetrating into the ground G at a constant speed by the static cone penetration test device 10 of FIG. (S01).

  Next, the ground density ρd is assumed (S02).

  Next, the relative density Dr is calculated from the obtained tip resistance qc and the vertical effective stress σv ′ obtained from the assumed ground density ρd (S03).

Conventionally, a relational expression between the tip resistance qc (kg / cm ² ) and the relative density Dr (%) has been proposed. An example of the relational expression is shown in the following expression (1) (page 305 of Non-Patent Document 1).
Dr = -98 + 66log (qc / √ (σv ')) (1)

When calculating the relative density Dr (%) from the tip resistance qc (kg / cm ² ) in Equation (1), the obtained tip resistance qc (kg / cm ² ) and the vertical effective stress σv ′ (kg / cm ² ), the vertical effective stress σv ′ can be obtained from the ground density ρd by the following equation.
e = ρs / ρd -1
γsat = ((ρs + ρw * e) / (1 + e)) * g
γ '= γsat-γw
σv '= Z' * γ '
However,
e: Pore ratio ρs: Soil particle density ρw: Pore water density
g: Gravity acceleration γw: Unit volume weight of pore water
Z ': Depth (m)

  The equation (1) indicating the relationship between the tip resistance qc, the vertical effective stress σv ′, and the relative density Dr is directly using a relationship equation generally proposed for sandy soil, but is not limited thereto. The actual ground may be investigated, and a relational expression suitable for the ground may be constructed and used.

  Next, the density ρd of the ground is calculated using the results of the minimum and maximum density tests of the soil conducted in advance and the calculated relative density Dr (S04). The soil minimum / maximum density test can be performed, for example, according to Japanese Industrial Standard (JIS A 1224: 2009) “Sand Minimum / Maximum Density Test Method”.

The dry density ρd (g / cm ³ ) can be calculated from the minimum density ρdmin (g / cm ³ ) and maximum density ρdmax (g / cm ³ ) of the soil according to the following equation (2).
ρd = (ρdmax ・ ρdmin) / (ρdmax-Dr (ρdmax-ρdmin)) (2)

  Next, the ground density assumed in step S02 is compared with the ground density (dry density) calculated in step S04, and it is determined whether or not they are equal (S05). When both are not equal, it returns to step S02, changes the assumed ground density, performs step S03, S04, and repeats these steps S02-S04 until it is judged that it is equal in step S05.

  The ground density when both are determined to be equal is determined as the ground density estimated value (S06).

  The ground density determined in the above steps S01 to S06 is at the depth position where the tip resistance qc is measured. By changing the depth position from the surface layer of the ground G to the depth direction and estimating the ground density at each depth position based on the tip resistance measured at each depth position, the density distribution of the entire ground is calculated. be able to.

  According to the ground density estimation method according to the present embodiment, without using a difficult-to-handle measuring device such as an RI cone penetration test, and without performing sampling for measuring the ground density, in situ. By conducting a static cone penetration test, the ground density can be calculated and easily estimated. Moreover, the density of granular material other than soil can be measured without sampling for measuring the ground density.

  In addition, any ground can be used as long as the cone can penetrate into the ground and the tip resistance can be measured, and the application range is extremely wide. For example, it is possible to measure the density of the ground formed by introducing granular materials other than sand such as steel slag and concrete waste.

  In addition, when it is necessary to grasp the wet density of the ground, it is necessary to grasp the saturation degree in advance. When saturation is not known in advance, it is possible to grasp the groundwater level from the water pressure response characteristics using a three-component cone type as a cone penetration tester, and to understand where the saturation is 100%. . About an unsaturated part, a saturation degree can be grasped | ascertained using a moisture meter as needed. In addition, since the density of the portion shallower than the target portion is required to calculate the density of the deep portion, more accurate density can be calculated by calculating from the shallow portion.

  In addition, for example, when embankment, reclamation or filling is performed using a predetermined material, the above ground density estimation method requires the minimum density and maximum density of the material. When calculating the density of ground that has been stuffed, it is necessary to perform sampling separately and measure the minimum and maximum densities.

  Next, a ground reclamation management method using the ground density estimation method of FIG. 1 will be described with reference to FIG. FIG. 3 is a flowchart for explaining steps S11 to S14 of the land reclamation management method using the ground density estimation method of FIG.

  First, earth and sand are thrown into the landfill target site (S11). Next, compaction is performed on the soil region formed by the introduction of soil by a predetermined compaction method (S12). As the compaction method, various known methods can be used. For example, vibration compaction by compacting the soil using a rolling load by a roller, a vibration load by a tamper, etc., and dropping a weight from a high place There is an impact type that tightens and a vibration rod that tightens the caisson filling material.

  Next, the static ground penetration test shown in FIGS. 1 and 2 is performed on the compacted ground, and the ground density is estimated as shown in FIG. 1 (S13). At this time, if necessary, the distribution of ground density is estimated in the same manner.

  Next, based on the estimated ground density and, if necessary, the distribution of the ground density, it is determined whether or not the distribution is an appropriate ground density and, if necessary, the ground density (S14). As a result, if it is determined that it is not appropriate, the process returns to the compaction step S12 and further compaction is performed. If it is determined to be appropriate, the process proceeds to the next step.

  According to the land reclamation management method of FIG. 3, it is easily confirmed by performing a cone penetration test whether or not the ground after compacting the earth and sand introduced in the land reclamation has achieved a predetermined ground density. Therefore, landfill management can be performed easily and reliably.

  In addition, for the ground after the earth and sand put in the ground reclamation is compacted, even when sampling for conventional ground density measurement is performed, the ground density estimation method according to this embodiment can be used together. The number of sampling points can be reduced, and landfill management can be efficiently performed. Further, by comparing the ground density measured by sampling with the ground density estimated by the estimation method of the present embodiment, the accuracy and validity of the ground density estimation method according to the present embodiment can be confirmed.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to a present Example. First, assuming the density (ρd) of the ground, the vertical effective stress σv ′ is calculated from the measured tip resistance (qc), and the relative density (Dr) is calculated by the equation (1) (calculated values in Tables 1 and 2). a). Next, the density (ρd) of the ground is calculated from the relative density (Dr), the minimum density (ρdmin), and the maximum density (ρdmax) by Equation (2) (calculated values b in Tables 1 and 2). In this way, the ground density is calculated at each depth Z ′ (m) from 0.5 m near the surface layer to a depth of 22.5 m. Table 1 below shows the initial value of each value. In the calculation, the soil particle density ρs is 2.65 g / cm ³ , but it is usually preferable to calculate from the soil particle density test result. The density ρw of the pore water was 1.03 g / cm ³ .

  Since the assumed ground density (ρd) shown in Table 1 is different from the calculated ground density (ρd), the assumed ground density (ρd) is changed, and the ground density is calculated again with this ground density. Repeat until the calculated ground density converges and becomes equal. Table 2 below shows the calculation results after the convergence in which both are equal. In Table 2, the density when the assumed ground density is equal to the calculated ground density is the estimated ground density (calculated value b) at the measurement point.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the ground density estimation method of the present invention is used in the ground reclamation management method of FIG. 3, but the present invention is not limited to this. For example, the ground density estimation method may be used as a compaction management method when compacting the ground. In addition, after charging the filling material into the caisson, the density due to the filled filling material is estimated by the ground density estimation method of the present invention, thereby controlling the filling of the caisson filling material. You may use for the input management method of material.

Moreover, although the static cone penetration test was used in this embodiment as the cone penetration test of the present invention, the present invention is not limited to this, and a dynamic cone penetration test may be used. The static cone penetration test may be, for example, a Dutch double tube cone penetration test or a single tube cone penetration test for measuring cone penetration resistance, in addition to the electric static cone penetration test. Specifically, the following cone penetration test can be used (see Non-Patent Document 1).
・ Simple dynamic cone penetration test (JGS 1433-2003)
・ Portable cone penetration test (JGS 1431-2003)
・ Dutch type double pipe cone penetration test (Japanese Industrial Standard JIS A 1220: 2001)
・ Electric static cone penetration test (JGS 1435-2003)

10 Static cone penetration test equipment 11 Penetration equipment 14 Cone G Ground

Claims (6)

A step of measuring the tip resistance by a cone penetration test at an in-situ measurement target of the ground density;
Assuming a ground density;
Calculating a relative density based on the measured tip resistance and the assumed ground density;
Calculating the ground density based on the minimum and maximum density test results of the soil obtained in advance and the calculated relative density;
Comparing the assumed ground density with the calculated ground density, if both are not equal, return to the ground density assumption step and change the assumed ground density, then the relative density calculation step and the ground density calculation step And, if equal, determining the ground density as a ground density estimate, comprising:   The ground density estimation method according to claim 1, wherein a plurality of points of tip resistance are measured in the depth direction by the cone penetration test, and a depth position at which the ground density is calculated is changed from the surface layer of the ground to the depth direction.   The ground density estimation method according to claim 1 or 2, wherein a relationship among the tip resistance, the relative density, and the ground density corresponding to the soil to be measured is obtained in advance. Throwing earth and sand into the landfill site;
Performing a compaction on the soil region formed by charging the soil;
Performing the ground density estimation method according to any one of claims 1 to 3 for the compacted soil region, and estimating the ground density;
Determining whether the ground density is a reasonable value based on the estimated ground density,
If the ground density is not a reasonable value, the ground reclamation management method returns to the compacting step. A step of compacting the ground to be compacted;
The step of estimating the ground density by performing the ground density estimating method according to any one of claims 1 to 3 for the compacted ground;
Determining whether the ground density is a reasonable value based on the estimated ground density,
If the ground density is not a reasonable value, the ground compaction management method returns to the compaction step. Charging the caisson with filling material;
Performing compaction on the filling material region formed by charging the filling material;
Performing the ground density estimating method according to any one of claims 1 to 3 for the compacted filling material region, and estimating the ground density;
Determining whether the ground density is a reasonable value based on the estimated ground density,
If the ground density is not an appropriate value, the method returns to the compacting step, and the caisson filling method is characterized.

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