JPS61137912A - Formation of underground column using water semi-permeable cloth - Google Patents

Abstract

PURPOSE:To form an underground column of a diameter larger than an excavat ed pit by a method in which a cylinder made of a water semi-permeable cloth, having closed tip portion, is penetrated to a given depth into the ground, and a cement mixture is injected into one end exposed to the ground's surface of the cylinder. CONSTITUTION:A cylinder 2 whose tip is closed, made of a water semi-permeable cloth, is penetrated to a given depth into a pit 1 drilled in the ground. Cement mortar 4 is injected into the upper opening 3 of the cylinder 2 through an injection hose connected to a cement mortar injection pump and hardened.

Description

[Detailed description of the invention] (Industrial application field).

The present invention relates to a method for constructing columnar bodies such as underground C2-forming scoops and anchors. .

(Conventional technology) 3: Iku: ni":::tt: 2::: 2. If it is sand, it should be buried underground as a sand pile (:・Promotes dewatering from the ground. In the case of mortar, water is dehydrated from the mortar poured inside to strengthen the mortar and create a slope protection. In both cases, reinforcement with a cloth-like material and good water permeability of the cloth-like material were utilized.

(Problem to be Solved by the Invention) Therefore, when attempting to produce a cylindrical body of a predetermined diameter by injecting mortar into a cylindrical body using a cloth-like material, C2 is simultaneously poured into the cylindrical body from the injected mortar. Through things like .

As dehydration begins, if the cylindrical body is long, the mortar will dehydrate and solidify on the way, so a cylindrical body with a specified diameter will be completed depending on the type of fabric, mortar injection speed, kiltar composition, etc. In some cases, the mortar dehydrated and solidified before pouring, making it impossible to pour the mortar.

Furthermore, even if a cylindrical body with a predetermined diameter is made, the mortar has already dehydrated and solidified by the time the cylindrical body is completed, so it is not possible to maintain the injection pressure any longer or increase the injection pressure even further than the predetermined diameter. It was impossible to produce a large-diameter cylindrical body.

(Means for Solving the Problems) In view of these problems, the present invention uses a semi-water-permeable cloth material that is relatively difficult to absorb water quickly;
Cylindrical body ζ: A columnar body of a predetermined diameter is placed underground without worrying about the composition of the hardened cement material or the injection speed of 8 degrees, etc., without premature dehydration and solidification of the injected cement hardened material such as mortar. This made it possible to easily create it.

That is, the present invention involves inserting a cylindrical body made of semi-permeable fabric whose tip is closed to a predetermined depth into the ground from the ground surface, and then injecting hardened cement from one end of the cylindrical body at the ground surface. To provide a method for constructing an underground columnar body using a semi-permeable cloth material, which is characterized by expanding the cylindrical body to a predetermined diameter and dehydrating the cylindrical body by It is resolved.

Ordinary cloth-like materials have general water permeability, but semi-water permeable cloth-like materials in the present invention refer to cloth-like materials that have this water permeability compared to ordinary cloth-like materials (compared to cloths with no water permeability). Specifically, at least 7
This refers to a cloth-like material that begins to permeate water only when water pressure on the order of atmospheric pressure acts on it, but if this minimum pressure varies slightly, it can be adjusted to the semi-temperature range referred to in the present invention by changing the composition of the cement hardening material, the injection speed, etc. The purpose as a water-permeable fabric is achieved.

Semi-permeable cloth like this can be made by tightly packing the weave of ordinary cloth such as nylon, but the cost is high, so it is possible to make it by pasting a thin plastic film or impregnating it with resin etc. Alternatively, it is better to coat it and give it a surface treatment. Easiest C: An example of a manufacturing method includes a method of thinly coating one surface of a cloth-like material with an acrylic resin or the like.

Additionally, semi-permeable fabrics made by this method have poor water permeability, so even when using fabrics that do not allow water to pass through unless the pressure is increased above a certain level, the cylindrical body is generally made of fabric. There is an axial seam to form the shaped object into a cylindrical body,
When internal pressure is applied, this seam opens a little and dewatering begins from there, so if a predetermined pressure is applied and maintained for a certain period of time, the same state as when water permeates through a cloth-like material can be obtained. Therefore, with regard to the water permeability of a cloth material, it is possible to use a cloth material with somewhat poor water permeability, as long as the pressure required to start water permeation as described above is maintained as the minimum pressure.

The outer diameter of the cloth-like cylinder used in the present invention is 20 cIR.
It is preferable to insert the cloth-like cylinder into the ground (the method of inserting the cloth-like cylinder is to first dig a hole with a specified diameter or less and insert the cloth-like cylinder into this hole, but if the ground is soft, the cloth-like cylinder can be inserted into the ground). It is also possible to grasp the tip of the cylindrical body with the end of the shaft and push it directly into the ground.If you make an excavation hole in advance and push the cloth-like cylindrical body into it, the diameter of the excavation hole should be It is sufficient if the diameter of the cylindrical body is large enough for two people, and it is sufficient if the diameter is about half of the predetermined diameter.

Furthermore, as the hardened cement material to be injected into the cylindrical body from the ground surface, cement mortar is most desirable from the viewpoint of fluidity, etc., but cement concrete, fill cement, etc. are also possible.

The semi-permeable phase cylinder made in this way does not easily dehydrate the cement hardened material and dehydrates only when a certain amount of pressure is applied. As the pressure inside the cylindrical body increases, the cylindrical body expands and dehydration begins (second stage).

(Example) An excavation hole with an outer diameter of ♂θ■ and a length of 41,000 m was provided underground, and a predetermined outer diameter of /30■, a length of θ00
- After inserting a cylindrical body made of a semi-permeable cloth-like material with a closed end using a steel rod, only the steel rod is pulled out, and an injector connected to a mortar injection pump is inserted into the opening at the top of the cylindrical body. A hose was tied and mortar was injected into the cylindrical body using a pump.

After injection started, the injection pressure did not increase until the cylindrical body was filled with mortar, but after it was filled, the cylindrical body expanded and its diameter increased, and the injection pressure increased until it reached the maximum pressure. At this point, the pump was stopped and the infusion was terminated.

As a result of excavation investigation later, the mortar of the cylindrical body was completely hardened and its outer diameter was /4t! It was wm.

The semi-permeable cloth material used was a nylon cloth material with a tensile strength of 2 j Oh/an, one side of which was waterproofed with acrylic resin.

(Effect of the invention) If this semi-permeable cloth-like cylinder is used, the mortar will dehydrate and solidify at an early stage, and there will be no problem in pouring the mortar.
Since the internal pressure can be maintained from the cylindrical body until the dewatering is completed, if the ground is soft, it is possible to insert the cloth-like cylindrical body into a small excavation hole (with a diameter larger than the diameter of the excavation hole) and pour the hardened cement from above. When press-fitting, it is possible to expand the excavation hole by the internal pressure of the hardened cement and create an underground column with a larger diameter than the excavation hole.Therefore, unlike conventional methods, it is necessary to prepare a large excavation hole in advance using large construction machines. It is sufficient to have the smallest hole into which the cloth-like cylinder can be inserted.In addition, in the case of soft ground, for example, with an N value of 2 or less, it is necessary to insert the cloth-like cylinder directly without making an excavation hole. Using a shaft or the like, it is possible to create a columnar body simply by inserting it into the ground.

[Brief explanation of drawings]

7A, B, and C are state diagrams showing each step of the present invention, and the person in FIG. 1 shows a state in which the cylinder 2 made of a semi-permeable cloth material is inserted into the ground. B in FIG. 1 shows a state in which hardened cement 4 is injected from one end 3 of the surface part of the cloth-like cylinder 2. C in Figure 7 shows the completed state after expanding underground, dehydrating and solidifying. 1: Excavation hole 2: Cylindrical body made of semi-permeable cloth 3: End of the surface part of the cylindrical body 4: Hardened cement body

Claims (1)

[Claims] After inserting a cylindrical body made of a semi-permeable fabric whose tip is closed to a predetermined depth into the ground from the ground surface, hardened cement is injected from one end of the surface of the cylindrical body to a predetermined diameter. A method for creating an underground columnar body using a semi-permeable fabric, characterized by dehydrating the cylindrical body while expanding the cylindrical body.