JP2012197583A - Ground strengthening method and wood pile for strengthening ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground strengthening method and a wood pile for strengthening ground, capable of strengthening weak ground without injecting a grout material underground, easily building a safe wood pile, and increasing the strength of the ground.SOLUTION: In order to achieve the purpose, in the ground strengthening method of the present invention, a wood pile 1 for strengthening ground including a spiral groove 3 formed on a side face of a columnar pile body part 2 is used, the wood pile 1 for strengthening ground is built underground while being rotated in the lowering direction of the wood pile 1 for strengthening ground by the spiral groove 3, and thus the ground is strengthened.

Description

The present invention relates to a technique for strengthening soft ground by building a wooden pile.

In soft ground such as sand, there is a risk of subsidence due to the construction of heavy buildings, and it cannot withstand vibrations caused by earthquakes. Therefore, ground reinforcement is performed by injecting grout materials such as cement milk and water glass into the ground, or by creating underground piles.

Further, in Patent Document 1, the tip of the wooden rod body is formed into a pointed shape, and the buried portion in the soil is parallel to one or more lateral grooves and / or the axis of the pile that intersect the axis of the wooden pile. A wooden pile with one or more longitudinal grooves is described. Patent Document 2 discloses a method of embedding a wooden pile having a spiral groove formed on its peripheral surface in the ground, placing an alkaline filling material around the pile center position on the ground, and setting the wooden pile to the winding direction of the spiral groove. Describes that the filling material is buried while being drawn into the ground around the pile by rotating and pressing in the opposite direction.

Registered Utility Model Publication No. 3086855 Japanese Patent Laid-Open No. 2007-70968

The ground strengthening method of injecting grout material into the ground requires using large-scale equipment such as mixers, compressors, and high-pressure grout pumps in addition to drilling tools such as augers. Construction is difficult in narrow spaces. There is concern about environmental pollution due to the injection material, and it is extremely difficult to dig up the hardener once injected into the ground, so the land cannot be returned to its original state.

The wooden stake described in Patent Document 1 is used as a retaining pile for forestry, as a pillar for a fence, as a marker pile for surveying during civil engineering work, as a splint for agricultural products (vine plants) widely used in agriculture and horticulture, Alternatively, it is used as a pillar of a tree, and further as a pillar of a protective fence for a pest (Patent Document 0004), and Patent Document 1 does not describe or suggest ground reinforcement.

The wooden pile of Patent Document 2 and its burying method are also used as piles for low-rise buildings such as detached houses built on soft ground (Patent Document 0015). Patent Document 2 also describes and suggests ground strengthening. Absent. In addition, by rotating and pressing in the direction opposite to the spiral winding direction, the cemented solidified material and other fillers are drawn into the ground around the pile. It is the same as the strengthening method. Therefore, in addition to the equipment for driving wooden piles, a mixer and the like are required. Furthermore, if it is rotated in the opposite direction to the direction of spiral winding, the resistance during driving will be extremely large, and it will be impossible to bury a wooden pile only by press-fitting.

The present invention provides a ground reinforcement method and a ground reinforcement wooden pile that can strengthen soft ground without injecting grout material into the ground, can easily build a safe wooden pile, and increase the strength of the ground. The purpose is to do.

In order to solve the above-mentioned object, the ground reinforcement method of the present invention uses a wooden pile in which a spiral groove is formed on the side surface of a columnar pile body, and the direction in which the wooden pile descends by the spiral groove The ground is strengthened by building it in the ground while rotating the wooden pile. The wooden pile can be rotated by hitting the upper end of the wooden pile in which the spiral groove is formed such that the helical angle with respect to the length direction of the pile main body portion is 30 ° or more and 45 ° or less. In addition, a wooden pile is built in the ground by applying a built-in force with a torque or striking force within a predetermined reference value, and when the wooden pile stops descending with the built-in force within the reference value, the driving is finished. The ground protrusion of the wooden pile may be cut.

Furthermore, in the wooden pile for ground reinforcement according to the present invention, a spiral groove is formed on the side surface of the columnar pile body portion, and the spiral angle of the spiral groove with respect to the length direction of the pile body portion is 30 ° or more and 45 ° or less. It is.

The ground reinforcing wooden pile of this invention has a spiral groove, and by rotating the wooden pile in the direction in which the wooden pile descends by the helical groove, the ground reinforcing wooden pile can be easily built. it can. Since the earth and sand almost remain in the ground, only the volume of the wooden pile is compressed and compacted. In addition, since earth and sand enter the spiral groove, the earth and sand around the adjacent wooden piles interfere with each other and resist each other against the vertical movement of the wooden piles. Stay away. No injection of grout material is required, construction can be done with simple equipment and processes, and there is no negative impact on the environment.

It is a front view which shows the wooden pile for ground reinforcement. It is sectional drawing which shows a spiral groove. It is a conceptual diagram which shows typically erection of the wooden pile for ground reinforcement. It is a conceptual diagram which shows typically the construction example in case there exists a stable ground in the lower part. It is a conceptual diagram which shows typically the effect | action of the wooden pile for ground reinforcement. It is a front view which shows the 1st example of the ground reinforcement method. It is a front view which shows the 2nd example of the ground reinforcement method. It is the same top view. It is a front view which shows the 3rd example of the ground reinforcement method. It is the same top view.

The form for implementing this invention is demonstrated. FIG. 1 is a front view showing a ground reinforcement wooden pile, and FIG. 2 is a cross-sectional view showing a spiral groove. The pile main body 2 of the wooden pile 1 for ground reinforcement is substantially cylindrical, and a spiral groove 3 is formed on the side surface of the pile main body 2.

The material of the ground reinforcement wooden pile 1 is wood, and it is sufficient if it has a predetermined strength, and cultivated materials such as cedar and cypress can be used. It is not always necessary to use wood for building materials, and it may be of thickness or length for use in ground reinforcement, and may be waste wood. Here, an example in which thinned wood is used will be described. Therefore, it can be implemented at a lower cost than timber for building materials, and contributes to effective use of thinned wood.

The thickness D is 0.20 to 0.25 m in diameter. The length L can be selected from about 4 to 10 m depending on the construction site, but here it is 4 m. This is a size that is usually cut out as a thinning material, is easy to handle, and can be used in many construction environments. The lower end 4 of the ground pile wooden pile 1 has a conical shape, which facilitates erection.

The spiral groove 3 is formed over almost the entire length of the pile body 2. When the pile main body 2 has a diameter of 0.20 to 0.25 m, the depth of the spiral groove 3 is preferably about 0.05 m. The cross section of the spiral groove 3 can be selected from a rectangle (FIG. 2a), a triangle (FIG. 2b), a semicircle (FIG. 2c), and the like.

Next, the angle of the spiral groove 3 will be described. The smaller the helix angle θ with respect to the length direction of the pile main body, the easier it is to build in the ground. In particular, in the range of 30 ° or more and 45 ° or less, as will be described later, it is also possible to build in by hitting the upper end. On the other hand, increasing the helical angle θ increases resistance to movement in the length direction in the ground instead of making it difficult to build.

The ground reinforcement wooden stake 1 may be one using wood as it is. As long as it is submerged in the ground, it will not corrode and is stable for a long time. However, it is also possible to apply or impregnate a material having antiseptic or ant-preventing action. In particular, impregnation with inorganic glass is preferable because it prevents termites and the like, is effective in preventing corrosion deterioration due to corrosive bacteria, and has little influence on the environment. By forming the spiral groove 3 and then immersing it in an inorganic glass raw material solution, it penetrates effectively to the inside.

FIG. 3 is a conceptual diagram schematically showing the construction of the ground reinforcement wooden pile. The direction of the spiral groove 3 may be either direction, but here, an example of a spiral in the direction of a right-hand thread will be described as shown in FIG. In this case, when it rotates clockwise as viewed from above, it proceeds downward. In this invention, it builds in the ground, rotating the wooden pile 1 in the direction in which the wooden pile 1 descend | falls by the spiral groove 3 in this way. In the invention of Patent Document 1, in order to introduce the filler, the pile is rotated and driven in the opposite direction, but in the present invention, the rotation direction is completely opposite.

As a method of erection while rotating, for example, there is a method in which the vicinity of the upper end of the ground reinforcing wooden pile 1 is gripped by a chuck and rotated by applying torque. A motor or the like provided in a small construction vehicle such as a construction pole can be used. As another method, it is possible to hit the upper portion of the ground reinforcement wooden pile 1. If the spiral groove is formed so that the spiral angle is not less than 30 ° and not more than 45 °, the ground reinforcement wooden pile 1 naturally rotates as it is lowered by the impact. This striking may also be performed with a hammer head provided in a normal construction machine. Further, it may be a combination of rotation and striking with a chuck.

Thus, the wooden pile 1 advances smoothly like a screw by building it in the ground while rotating the wooden pile 1 in the descending direction. Soil stability is not disturbed because the ground is hardly agitated. Also, the earth and sand are hardly discharged to the ground, and the volume of the wooden pile 1 is compressed and compressed.

FIG. 4 is a conceptual diagram schematically showing a construction example when there is a stable ground in the lower part. The upper part of the construction site is a soft ground such as sand or gravel, and there is a stable ground below it. The ground pile wooden pile 1 is built in the ground while restricting the built-in force by torque or striking force within a predetermined reference value at the construction site. In soft soil, the wooden pile 1 is lowered by the built-in force within the reference value, but the progress stops when reaching a firmer stable ground. In this case, the torque or striking force is not intentionally increased, and the building is finished there. This is because, when there is a stable ground, it is more advantageous to leave the stability than to disturb the ground with the wooden pile 1. In this case, the portion that was not built on the ground protrudes, but it can be easily cut with a saw or the like because it is a wooden pile, and can be aligned with the top of the other wooden pile.

The ground reinforcement wooden pile 1 is built at a predetermined interval in a range where the ground is strengthened. This ground reinforcement wooden pile 1 is a hard and large structure compared to earth and sand, and stabilizes the ground. Furthermore, within the range, the earth and sand are compacted by the volume of the wooden pile 1 for ground reinforcement.

FIG. 5 is a conceptual diagram schematically showing the operation of the ground pile wooden pile. Since the earth and sand around the ground reinforcing wooden pile 1 also enters the spiral groove 3 and a strong frictional force is generated, the movement of the ground reinforcing wooden pile 1 is restricted. Furthermore, adjacent wooden piles 1 for ground reinforcement interfere with each other and regulate their movements. For example, it is assumed that a downward force is applied to a certain ground reinforcement wooden pile 1n. However, when the ground reinforcement wooden pile 1n is going to descend, a clockwise rotation occurs, and the surrounding earth and sand must also rotate. Since this earth and sand rotation is transmitted to the adjacent ground reinforcement wooden piles 1n-1 and 1n + 1 as a leftward rotation, they tend to rise in reverse. Therefore, the descent of the ground reinforcement wood pile 1n is prevented by the adjacent ground reinforcement wood piles 1n-1, 1n + 1.

In addition, the rotation of the ground reinforcement wooden pile 1n + 1 is further transmitted to the adjacent ground reinforcement wooden pile 1n + 2, which tends to descend. When the ground reinforcement wooden pile 1n tries to move in this way, the force in the opposite direction acts alternately on the surrounding ground reinforcement wooden pile, and a stable state that cannot be raised or lowered as a whole is forced. The

Next, examples of the present invention will be described.

FIG. 6 is a front view showing a first example of the ground strengthening method. It is applied to the ground improvement of construction sites for relatively low-rise buildings such as houses. Under the building, the wooden pile 1 for ground reinforcement is built relatively densely. Sand support is applied where the foundation is supported. Thus, by strengthening the ground and building the foundation 6 on it, it is possible to prevent the settlement of buildings and improve the earthquake resistance. It can also be applied to strengthen the surroundings and slopes. In this case, it can be built at relatively wide intervals while matching the strength of the ground. In addition, the slope may be built vertically or perpendicular to the slope.

Since this ground strengthening method does not require a large facility, it can be easily carried out in a narrow place such as a residential area, and can also be applied to a slope with a strong slope. Moreover, if the ground reinforcement wooden pile becomes unnecessary in order to divert this land in the future, it can be easily removed by rotating in the reverse direction and returned to the state before construction.

FIG. 7 is a front view showing a second example of the ground strengthening method, and FIG. 8 is a plan view. This is an example applied to a pedestrian path. The ground is skied to a predetermined depth, and ground reinforcement wooden piles are built there. Build so that the top edge is at the ground level.

Fill the skid area with sand, water-tighten, then finish the empty mortar joint mortar. The upper surface of the wooden pile for ground reinforcement is exposed. In addition, a dent may be formed in the center of the upper surface of the ground reinforcement wooden pile to increase friction.

FIG. 9 is a front view showing a third example of the ground strengthening method, and FIG. 10 is a plan view. This is an example applied to a light vehicle passage. The ground is skied at a depth equivalent to the length of the road surface finishing material, and a wooden pile for ground reinforcement is built there. It is built to the extent that all the piles for ground reinforcement are filled.

Next, the road surface finishing material 5 is arranged on the ground reinforcement wooden pile. This road surface finishing material 5 is also a member using thinned wood and the like, and an annular recess is provided on the side surface in the central portion of the length, thereby increasing the stability in the ground. Here, it is a substantially cylindrical outer shape. A recess for increasing friction is formed in the center of the upper surface. The road surface finishing material 5 is preferably arranged more densely than the ground reinforcement wooden pile.

Fill the skid area with sand, water-tighten, then finish the empty mortar joint mortar. The upper surface of the road finishing material is exposed.

1. Wooden pile for ground reinforcement 2. 2. Pile body part 3. Spiral groove 4. Tip 5 Road finishing material

Claims (4)

Strengthen the ground by using wooden piles with spiral grooves formed on the sides of the columnar pile body, and building them in the ground while rotating the wooden piles in the direction in which the wooden piles descend by the spiral grooves How to strengthen the ground. Claim that the upper end of the wooden pile formed with a spiral groove is hit so that the helical angle with respect to the length direction of the pile main body portion is 30 ° or more and 45 ° or less, and the wooden pile is built in the ground while rotating. The ground strengthening method according to 1. A wooden pile is built in the ground by applying a built-in force with a torque or striking force within a predetermined reference value, and when the wooden pile no longer descends with the built-in force within the reference value, the driving is finished. The ground reinforcement method of Claim 1 or Claim 2 which cut | disconnects the ground protrusion part of a pile. A ground reinforcing wood pile in which a spiral groove is formed on a side surface of a columnar pile body portion, and a spiral angle of the spiral groove with respect to a length direction of the pile body portion is 30 ° or more and 45 ° or less.

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