JP2019157398A - Fastener construction method - Google Patents

Abstract

To provide a construction method which can simply and reliably construct fasteners against soil and stabilizes and locks the fasteners in soil.SOLUTION: It is a pile-shaped component of which one end part is the head part and the other end part is the tip part, and a fastener on which screws are formed at least on the outer periphery of the tip part side is driven into soil. A lower hole into which the fastener can be inserted is drilled in soil and filling materials are filled into the lower hole, the tip part of the fastener hits the surface of sand inside the lower hole and the fastener is screwed into sand by being rotated with the central axis of the fastener being the pivot.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a method for constructing a fastener that is driven into soil from above the grass protection sheet, for example, in order to lock the grass protection sheet covering the surface of the soil to the soil.

In civil engineering and construction, construction in which a pile-shaped anchor, that is, a fastener is driven into the soil, is common.
For example, when covering the soil surface with a weedproof sheet as a countermeasure against weeds on idle land under the bridge or at the shoulder of the road, it is a short time It is practical as a low-cost herbicidal measure and actually has a lot of construction results.

Among such construction methods, there is a method using a fastener having a head that can correspond to a rotary tool at one end and a thread provided from the tip of the other end.
This fastener causes the fastener to enter the ground by the rotational force of the screw thread.
This fastener is excellent in workability and pull-out resistance.

However, if there are many stones in the soil where the fastener is driven, the fastener cannot enter the soil.
In this case, it is necessary to make a hole in advance at the entry position of the fastener during construction.

  In the case of construction with this pre-drilling, the fasteners cannot be properly fixed to the soil due to the location of the boulders in the soil, the shape of the drilling holes, etc., and the pull-out strength of the fasteners also varies. There was a problem that the uniform construction was difficult.

JP2015-101920A

  The present invention has been made in order to solve the above-described problem, and enables a fastener to be easily and reliably applied to soil, and is stable in a state in which the fastener is maintained at a certain pull-out strength. The purpose is to enable the construction to be locked and to make the fasteners homogeneously constructed.

In order to achieve the above object, the method of constructing the fastener according to the present invention is as follows.
A pile-shaped member, where one end is a head, the other end is a tip, and a fastener is formed at least on the outer periphery on the tip side into the soil. A construction method,
A drilling step for drilling a pilot hole capable of inserting a fastener into the soil;
A filling step for filling the lower hole with a filler;
A locking step of screwing the fastener into the sand by applying the tip of the fastener to the surface of the sand in the pilot hole and rotating the central axis of the fastener as a rotation axis.

  According to the present invention, the fastener construction method is characterized in that, in the above method, the filler is sand.

In addition, according to the present invention, the fastener construction method is the above method,
A locking structure that is detachable from the rotary tool is provided on the head of the fastener,
The locking step is characterized in that the fastener is screwed into the soil using a rotating tool connected to the locking structure of the head.

In addition, according to the present invention, the fastener construction method is the above method,
In the locking step, the rotary tool used for screwing is an electric tool, and measures the current consumption value at the time of screwing,
Before installing the fasteners, implement the fasteners on the soil and perform the preparation step to pull out and the estimation formula identification step,
This preparatory step
A test drilling step for drilling a test pilot hole capable of inserting a fastener into the soil;
A test filling step of filling the test pilot hole with a filler;
Applying the tip of the fastener to the surface of the sand in the test pilot hole, unscrewing the power tool and rotating the fastener around the center axis, screw the fastener into the sand, and current consumption during screwing A test locking step for measuring the value;
Pulling out the fastener screwed by the test measurement step using a pull-out tester and measuring the pull-out strength; and
The estimation formula identifying step is
The above preparation step is executed a plurality of times, and a regression line corresponding to the soil and the rotary tool is obtained from the correlation between the consumption current value obtained in each preparation step and the consumption current value. The strength constant of the soil, and using the strength constant to obtain an estimation formula of the pullout strength,
In the locking step, the current consumption value at the time of screwing is measured, and the pullout strength is estimated from the current consumption value measured in the locking step based on the pullout strength estimation formula obtained in the estimation formula specifying step. Features.

In addition, according to the present invention, the fastener construction method is the above method,
The estimation formula is the following formula.
A = 0.5245 + 0.6026 × B
A: Estimated pullout strength (kN)
B: Current consumption value (seconds over 3.0A)

  Further, according to the present invention, in the above-described method, the fastener construction method is such that the distance between the inner peripheral surface of the pilot hole and the outer peripheral surface of the fastener is 3 to 4 times the height of the thread of the fastener. It is characterized by a double distance.

  In the present invention described above, the fastener can be reliably fixed to the soil while maintaining a certain level of pullout strength. For example, when the soil surface is to be covered with a weedproof sheet, the weedproof developed on the soil surface By driving a fastener into the sand filling position from above the sheet, for example, the weedproof sheet can be easily and firmly locked to the soil surface.

FIG. 1 is a flowchart showing a flow of a fastener construction method according to the present invention. FIG. 2 is an explanatory view showing the steps of the fastener construction method shown in FIG. FIG. 3 is a list showing conditions of the construction experiment by the construction method of the fastener shown in FIG. FIG. 4 is an example showing a change in current consumption obtained by the construction experiment of FIG. FIG. 5 is an example showing the results of the construction experiment of FIG. FIG. 6 is an example showing the result of the construction experiment of FIG. FIG. 7 is an example showing the results of the construction experiment of FIG. FIG. 8 is an example showing the results of the construction experiment of FIG. FIG. 9 is an example showing the results of the construction experiment of FIG. FIG. 10 is an example showing the results of the construction experiment of FIG. FIG. 11: is a graph which shows the estimation formula of the consumption current value and the drawing strength in the construction method of the fastener concerning this invention.

The present invention, when driving a fastener into the soil, drill a pilot hole into which the fastener can be inserted at the screwed position of the soil, fill the pilot hole with sand, and on the surface of the sand in the pilot hole, By applying the front end of the fastener and rotating the central axis of the fastener, and screwing the fastener into the sand, the fastener is easily and reliably driven into the soil.
Hereinafter, based on an Example, this invention is demonstrated in detail.

  FIG. 1 is a flowchart showing the flow of the fastener construction method according to the present invention, FIG. 2 is an explanatory diagram showing the steps of the fastener construction method shown in FIG. 1, and FIG. 3 is the fastener shown in FIG. FIG. 4 is an example showing changes in the current consumption obtained by the construction experiment of FIG. 3, FIG. 5 is an example showing the results of the construction experiment of FIG. 6 is an example showing the result of the construction experiment in FIG. 3, FIG. 7 is an example showing the result of the construction experiment in FIG. 3, FIG. 8 is an example showing the result of the construction experiment in FIG. 3, and FIG. FIG. 10 is an example showing the result of the construction experiment of FIG. 3, and FIG. 11 is a graph showing an estimation formula of the current consumption value and the pull-out strength in the fastener construction method according to the present invention. It is.

First, based on FIG. 1, the outline | summary of the mounting method of the fastener concerning this invention is demonstrated.
In the present invention, it is a pile-shaped member with respect to soil, one end is a head, the other end is a tip, and at least a screw is formed on the outer periphery on the tip side. Put the tool into the soil.

In the present invention, when the fastener is driven into the soil, as a preparation for driving the fastener, a pilot hole into which the fastener can be inserted is drilled (drilling step S01).
The prepared hole is drilled in the soil using a rotary tool such as an electric drill.

  The diameter of the lower hole may be set so that, for example, the distance between the inner peripheral surface of the lower hole and the outer surface of the fastener is about 3 to 4 times the thread height of the fastener. Preferably, specifically, when the thread height is 1.6 mm, the sense of the outer surface of the fastener and the inner peripheral surface of the lower hole is set to about 4.2 to 6.7 mm. Is preferred.

Next, sand is filled in the drilled pilot hole as a filler (filling step S02).
The sand as the filler may be general-purpose sand used for various purposes in general civil engineering.

  Next, the front end of the fastener is applied to the surface of the sand filled in the pilot hole, and the fastener is screwed into the sand by rotating about the central axis of the fastener, and the fastener is locked to the soil. (Locking step S03).

  This fastener has, for example, a locking structure that can be attached to and detached from the rotary tool at its head, and the locking step S03 uses a rotary tool connected to the locking structure of the head, It is executed by screwing into.

This locking structure is, for example, a bolt head, but is not limited to this as long as it can be attached to and detached from the rotary tool.
In the present invention, the fastener is locked to the soil as described above.

Next, based on FIG. 2, the construction of the fastener by the above method will be described based on a specific embodiment.
In FIG. 2, 1 is soil, 1a is a pilot hole, 2 is a filler, 3 is a fastener, 30 is a screw thread, and 31 is a locking structure.

In this example, a fastener was applied to soil 1 with a lot of boulders.
First, the lower hole 1 a was drilled in the soil 1.

  Next, sand was filled in the lower hole 1a as the filler 2.

  Next, the front end of the fastener 3 is applied to the center of the emphasis agent 2 filled in the pilot hole 1a, and the fastener 3 is attached using a rotating tool (not shown) connected to the locking structure 31 of the head of the fastener. Screwed into soil 1.

  Due to the screwing of the fastener 3, the compression force by the fastener 3 acts along a plane direction perpendicular to the central axis of the fastener 3, that is, from the outer peripheral surface of the fastener 3 toward the inner peripheral surface of the lower hole 1 a. Acting toward the inner peripheral surface of the lower hole 1a, compressive stress is generated on the inner peripheral surface of the lower hole 1a.

  This stress increases the step stress between the filler and the inner peripheral surface of the lower hole 1a, and ensures the pull-out strength of the fastener.

Here, in the construction of the fastener, a preparation step and an estimation formula specifying step necessary for screwing the fastener with a quality higher than a predetermined pulling strength will be described.
In the preparation step, first, a test pilot hole capable of inserting a fastener into the soil is drilled (test drilling step).

  Next, the test pilot hole is filled with a filler (test filling step).

  Next, apply the tip of the fastener to the surface of the sand in the test pilot hole, unscrew the power tool and rotate the fastener's central axis around the rotation axis, and screw the fastener into the sand. Is measured (test locking step).

  Next, the fastener screwed in the test measurement step is pulled out using a pull-out tester, and the pull-out strength is measured (pull-out strength measurement step).

  The estimation formula specifying step executes the above preparation step a plurality of times, obtains a regression line corresponding to the soil and the rotary tool from the correlation between the consumption current value obtained in each preparation step and the consumption current value. The slope of the regression line is used as the soil strength constant, and the strength strength constant is used to obtain the pullout strength estimation formula.

  Then, in the locking step, the current consumption value at the time of screwing is measured, and the pullout strength is estimated from the current consumption value measured in the locking step based on the pullout strength estimation formula obtained in the estimation formula specifying step. .

  As described above, it is possible to estimate the pullout strength from the current consumption value, so that the current consumption value when the fastener is screwed in can be monitored, and the construction of the fastener that can expect the pullout strength above a certain level can be secured. It becomes like this.

  Here, the preparation step and the estimation formula specifying step will be verified and explained based on a concrete construction experiment.

Here, in order to verify the securing of the pull-out strength, a construction experiment was carried out by the above method under the conditions shown in FIG.
As the soil ground conditions, a total of six locations were selected, one concrete for assuming a hard ground and five from the idle land under the bridge.

The true value of the pull-out strength was measured using a pull-out tester after the construction.
Moreover, as the filler, general-purpose and inexpensive commercially available sand was adopted.

In addition, three types of drilling hole diameter and sand particle size were set, and the influence on the pull-out strength was confirmed.
In this experiment, it was also verified whether or not a positive correlation was found between the current consumption during screwing and the pullout strength of the power tool used for screwing the fastener.

  The power consumption value of the power tool used for screwing the fastener is measured by connecting a clamp-on probe that can measure the current value to the cord of the power tool and measuring the power consumption simultaneously with screwing the fastener using a data logger. I got it.

The acquired current consumption value is as shown in FIG.
In FIG. 4, A is the ultimate peak value (A), B is the cumulative current value (A) with a current value of 3.0 A or more, C is the cumulative current value (A) from the start of screwing to the final stage, and T is The time (S) when the current value is 3.0 A or more.

  In the above experiment, a time (seconds) of a current ground of 3.0 A or more was adopted as a value representing the correlation between the current consumption value and the pullout strength.

The results of the construction experiment are as shown in FIGS.
FIG. 5 is an experiment conducted on concrete assuming hard soil, and FIGS. 6 to 10 are results of experiments conducted on soil under various conditions as soil, specifically, pulling strength. And the current consumption value.

The above relationship is shown as a graph with the vertical axis representing the true drawing strength and the horizontal axis representing the number of seconds with a current consumption value of 3.0 A or more.
The number of experiments for the concrete in FIG. 5 was 27 times for each test condition repeated three times, and for the actual ground, each experiment condition was set once for a total of 9 times.

The above experimental results will be considered below.
First, focus on the slope of the regression line of each graph.
In hard concrete (FIG. 5), the value of inclination is large.

On the other hand, as shown in the photograph in the figure, the soil A with a lot of coarse gravel (Fig. 6) is similar to the concrete and the soil B with a lot of gravel (Fig. 7) and In the case of soil C with a lot of gravel (FIG. 8), the inclination tends to decrease in that order.
The above shows that the slope of the regression line as an estimation formula is the internal friction angle, which is the soil strength constant.

Next, consider the regression line intercept.
In addition, adhesive force shows the resistance exhibited by the bonding force between the soil particles by the adsorbed water of the soil particles.

  When the water content ratio carried out according to the ground conditions is confirmed, soil B (6.4%) and soil C (9.6%) with high water content have large intercept values, while soil A (3 with low water content) (3 .4%) shows that the value of the intercept tends to be small, and thus it is clear that the intercept obtained by this estimation formula shows adhesive strength.

  An example of a graph showing the relationship between the power consumption value of screwing and the pullout strength obtained from the above experimental results is as shown in FIG. 11, and the estimation formula obtained from the results of this construction experiment is as follows. is there.

A = 0.5245 + 0.6026 × B
A: Estimated pullout strength (kN)
B: Current consumption value (seconds over 3.0A)

  From the above results, the relationship between the pullout strength and the current consumption value is not significantly different between combinations of different drilling diameters and filler particle sizes. Therefore, in the present invention, commercially available sand can be used as it is. It is possible and is not affected by drilling errors.

  In addition, when the required pullout strength is kN, a certain pullout strength can be secured by providing a threshold value for the current consumption value when the fastener is screwed, and quality control becomes possible.

  In the above experiment, soil D (FIG. 9) and soil E (FIG. 10) were soils on which soft topsoil was deposited, and a predetermined pulling strength could not be obtained.

  Therefore, it has been found that the above experiment is useful as data for grasping the applicability of the estimation formula.

  In addition, the strength constant (obtained from the regression line) included in the above estimation formula is changed depending on the combination of various conditions such as the soil subjected to the construction experiment, the diameter of the pilot hole, the fastener, and the tool used in the construction experiment. The

  For this reason, before constructing the soil on the fastener, it is recommended to execute the above preparation step and the estimation formula specifying step, and obtain an estimation formula corresponding to the soil in advance.

  Further, for example, when the combination of the diameter of the pilot hole, the fastener, and the tool is constant, the model soil as an index is selected, and the model estimation formula for the soil is acquired in advance, For the deemed soil, a corresponding model estimation formula may be employed and the fasteners may be constructed.

  According to the above-mentioned successful method of the fastener according to the present invention, when the fastener is applied to non-soft soil, the pullout strength can be increased, and the fastener is firmly attached to the soil with a certain quality. You will be able to type in.

  In addition, it is possible to estimate the pull-out strength by measuring the current consumption value at the time of construction of the fastener, and at the time of construction, it is possible to check whether the construction has been performed with a certain quality ensured. Become.

  In the above embodiment, the diameter of the pilot hole is not limited to the above embodiment as long as the actually required pullout strength can be secured in the calculation of the estimated pullout strength.

Further, the filler is not general-purpose sand but may be a dedicated filler blended for this construction, or a special filler may be diverted.
Further, the present invention can be freely modified within the scope of the present invention, and is not limited to the above-described embodiments.

  In the present invention, it is possible to confirm whether or not the fastener is being constructed while confirming whether or not the fastener can be applied to the soil easily and reliably, and whether or not the construction is being performed with a pulling strength of a certain level or more. Therefore, for example, it becomes possible to easily and surely lock the weedproof sheet developed on the surface of the soil with respect to the soil, and it is possible to lay a high-quality weedproof sheet at a low cost. High availability.

DESCRIPTION OF SYMBOLS 1 Soil 1a Pilot hole 2 Filler 3 Fastener 30 Screw thread 31 Locking structure

Claims (6)

A pile-shaped member, where one end is a head, the other end is a tip, and a fastener is formed at least on the outer periphery on the tip side into the soil. A construction method,
A drilling step for drilling a pilot hole capable of inserting a fastener into the soil;
A filling step of filling the lower hole with a filler;
A locking step of screwing the fastener into the sand by applying the tip of the fastener to the surface of the sand in the pilot hole and rotating the central axis of the fastener around the rotation axis. Method.   The method for constructing a fastener according to claim 1, wherein the filler is sand. A locking structure that is detachable from the rotary tool is provided on the head of the fastener,
The fastening method according to claim 1 or 2, wherein the locking step uses a rotary tool connected to the locking structure of the head to screw the fastener into the soil. In the locking step, the rotary tool used for screwing is an electric tool, and measures the current consumption value at the time of screwing,
Before installing the fasteners, implement the fasteners on the soil and perform the preparation step to pull out and the estimation formula identification step,
This preparatory step
A test drilling step for drilling a test pilot hole capable of inserting a fastener into the soil;
A test filling step of filling the test pilot hole with a filler;
Applying the tip of the fastener to the surface of the sand in the test pilot hole, unscrewing the power tool and rotating the fastener around the center axis, screw the fastener into the sand, and current consumption during screwing A test locking step for measuring the value;
Pulling out the fastener screwed by the test measurement step using a pull-out tester and measuring the pull-out strength; and
The estimation formula identifying step is
The above preparation step is executed a plurality of times, and a regression line corresponding to the soil and the rotary tool is obtained from the correlation between the consumption current value obtained in each preparation step and the consumption current value. The strength constant of the soil, and using the strength constant to obtain an estimation formula of the pullout strength,
The current consumption value at the time of screwing is measured in the locking step, and the screwing strength is estimated from the current consumption value measured in the locking step based on the pull-out strength estimation formula obtained in the estimation formula specifying step. 3. A construction method of the fastener according to 3. The construction method of the fastener according to claim 4, wherein the estimation formula is the following formula.
A = 0.5245 + 0.6026 × B
A: Estimated pullout strength (kN)
B: Current consumption value (seconds over 3.0A)   The fastener according to any one of claims 1 to 5, wherein the distance between the inner peripheral surface of the lower hole and the outer peripheral surface of the fastener is a distance that is three to four times the height of the thread of the fastener. Construction method.