JP2003193475A - Slope stabilization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a work method having improved safety and workability when performing inverted working in which the work is carried out by cutting the slope of collapsible natural ground from the top to downward stepwise. <P>SOLUTION: For a proposed cutting area 2B, a solidifying material 6 is penetrated in advance through a filling pipe 5 in surrounding ground of a portion 3B which becomes a cutting surface, and the ground is stabilized based on the solidification. Thereafter, the proposed cutting area 2B is cut and removed, and an anchor body 11 is driven from the exposed cutting surface 3B to the ground of the natural ground 1. A series of these work is sequentially repeated to a lower proposed cutting area and a slope can be developed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope stabilizing method which is improved in safety and workability in forming a natural slope by reverse winding.

[0002]

2. Description of the Related Art Conventionally, various reinforcement construction methods have been applied to slopes, such as measures against landslides on rock slopes and steep slopes on cut slopes. As a typical example of this reinforcement method, a large number of reinforcing bars, rock bolts or anchors such as ground anchors are driven from the surface of the natural ground toward the inside of the natural ground at appropriate intervals, and then placed in the driving holes. A method is widely adopted in which an appropriate grout material is filled to fix the anchor body to the natural ground, and the shear resistance is used to enhance the stability of the entire slope. By the way, there is a risk that the surroundings of the cut surface will collapse during excavation, especially in unstable ground where it is assumed that the slope will collapse due to the cutting of the ground. Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-61840 or No. 11-310925, the ground slope is cut off stepwise from the upper part to the lower part of the slope while appropriately reinforcing it with the anchor body. So-called "reverse winding construction" is generally performed.

The technique disclosed in Japanese Patent Laid-Open No. 11-61840 is intended for a primary bearing plate having a simple structure for ensuring short-term slope stability during construction and for long-term slope stabilization after construction. The secondary bearing plate by concrete spraying,
It is characterized by being used with a lock bolt.
In this case, due to the slope restraining effect of the primary bearing plate, even if the strength of the mortar or concrete of the secondary bearing plate is not fully developed during hardening, construction of the lower lock bolt from the upper end to the lower end of the slope is performed. It is possible to perform the cutting work at a height that is possible. In addition, JP-A-1
In the technique described in Japanese Patent Publication No. 1-310925, an anchor body is placed in the ground every time the rock is excavated in stages from above, and the cut surface is pressed around the protruding portion of the anchor body from the ground surface. The pressure receiving pad is formed of a hardening material such as concrete, and the pressure receiving pad integrated with the anchor body cuts the lower step while temporarily or temporarily fixing the earth and sand load. These operations are repeated downward, and after all cutting work is completed, a precast earth retaining block is fixed to the head of each anchor body.

[0004]

However, in the above-mentioned conventional examples, since the cutting work is performed before the stabilization by the anchor body is performed in the first step on the upper part of the slope where cutting is started, There has been no improvement in the risk of collapse associated with the first cut. Furthermore, until the primary pressure bearing plate of the former or the pressure receiving pad of the latter for temporarily stopping the collapse of the cut surface is properly installed, the risk of collapse becomes higher especially around the cut part. ing. Moreover, in any case, since the cut surface is pressed by the member of the installation surface, which is not so large in view of the purpose of use, it is not possible to expect great effect on the suppression effect. Therefore, work under the condition where such a danger remains is unavoidable and causes a decrease in work efficiency. The present invention has been made in view of these problems of the prior art, and an object thereof is to provide a slope stabilization method with improved safety and workability.

[0005]

In order to solve the above problems, in the present invention, in the slope stabilization method in which the ground slope is gradually cut from above while being reinforced with an anchor body, the cut slope is cut against the planned cut area. A solidifying material is preliminarily infiltrated into the ground around the part to be the soil surface through a drilling hole, and the ground is improved based on the solidification, and then the planned cutting area is cut off and the exposed cut surface is removed. The feature is that an anchor body is driven toward the ground of the natural ground, and the slope is constructed by sequentially repeating these series of work in the planned cut area below.

[0006] That is, according to the above construction, in the case where reverse winding construction is performed in which the ground slope, which is in danger of collapsing due to excavation, is cut off from the top in a stepwise manner, prior to cutting work, appropriate consolidation is performed in advance. Since the ground is improved in the planned cutting area by injecting the timber, the slope collapse can be reliably prevented even in the first stage construction, and the cutting work and anchor body placement work at each subsequent stage. Etc. can be performed safely. Therefore, since the work is performed under the condition that the safety is sufficiently ensured, the efficiency is greatly improved as compared with the conventional construction method.

Further, in the above-mentioned structure, the solidifying material to be injected into the periphery of the cut surface through the drilling is mainly composed of fine particle cement having an average particle size of 6 μm or less and alkali metal silicate and having a solid content of 10 to 10. A 50% by weight aqueous suspension is particularly suitable due to its mode of use. That is, the solidified material in the form of suspension has a characteristic that the cement dispersed in the liquid has an extremely small particle diameter, and thus it easily penetrates into the cracked portion of the ground or the sandy ground. In this case, when the alkali metal silicate and the cement component are mixed, the reaction between the two causes the aqueous suspension to gel and stop flowing, but the flowing stop time can be appropriately adjusted. Therefore, the solidifying material can be surely infiltrated into the desired range from the drilled hole, and the solidifying material is not washed away even if there is spring water from the natural ground. That is, if this solidifying material is used, it is possible to reliably prevent the slope from collapsing when the soil is cut by infiltrating into the ground in a necessary area and solidifying.
If the solid content in the aqueous suspension is too high, not only the injection operation into the drilling hole is difficult but also the permeation into the peripheral area of the drilling hole is insufficient. On the other hand, if the amount is too small, it becomes difficult to cure the solidifying material itself, and it is more preferably in the range of 15 to 40% by weight.

The solidifying material according to claim 2
Will be described in detail. First, for fine particle cement, the average
Any cement with a particle size of 6 μm or less, for example, ordinary
Portland Cement, Early Strength Portland Cement, Medium
Various types of cement such as normal heat Portland cement are used.
be able to. Also, if necessary, lime, plaster, doloma
For it plaster, fly ash, granulated blast furnace slag, etc.
Additives may be added. The particle size was expressed by the specific surface area.
In case of 5000 cm^Two/ G or more, preferably
10000 cm^Two/ G or more. Cement particle ratio chart
The larger the area, the higher the permeability, and the stronger the ground is improved.
Can be done, but if it is too large, the alkali
When mixed with metal silicate to form an aqueous suspension,
It is easy to use and is disadvantageous in terms of cost.
00 cm^Two/ G-15000 cm ^Two/ G range is most preferred
Good The amount used in the solidifying material takes into consideration the ground improvement effect.
Then, it is preferable to mix as much as possible, but it will increase.
The viscosity of the aqueous suspension increases with. Therefore, note
Of cement with consideration of the balance of injection effect and viscosity
The total amount is preferably 1 liter of the aqueous binder suspension.
Is 100-500 g, more preferably 150-350 g
Is the range.

Next, examples of the alkali metal silicate include potassium silicate and sodium silicate, and sodium silicate is preferable from the viewpoint of cost. These alkali metal silicates have a molar ratio (Si
O ₂ / M ₂ O: provided that M represents an alkali metal atom,
It is preferably in the range of 2.0 to 4.0 in view of the flow stop time of the solidified material prepared in the suspension form. That is, this solidifying material is injected into the drilling hole that reaches from the surface of the ground slope to the periphery of the cut surface and diffuses and permeates into the surrounding area, but if the flow stop time is too short, the solidifying material will The flow may be stopped before it has sufficiently penetrated, and its injection effect may be insufficient. On the contrary, if the flow stop time is extremely long, the hardening range may be unclear and the ground may not be improved appropriately. Therefore, SiO ₂ in the alkali metal silicate in the solidified material prepared as a suspension is used.
By setting the ratio of minutes and the molar ratio in the alkali metal silicate within a specific range, the flow stop time becomes more appropriate, and a clear gel body is formed at the time of the flow stop,
Even if there is spring water from the ground, it is possible to improve the ground accurately without the solidifying material flowing out.

The above-mentioned specific range is x in the molar ratio of the alkali metal silicate (SiO ₂ / M ₂ O: M is an alkali metal atom), x is the alkali metal silicic acid in 1 liter of the binder suspension. When the ratio of SiO ₂ in the salt is y, it is a range that satisfies the relationships represented by the following formulas (1) to (5). (1) y ≤ 200 (2) x ≥ 2.4 (3) x ≤ 4.0 (4) y ≥ 120x-260 (however, 2.4 ≤ x ≤
3.0 range) (5) y ≧ 100 (however, 3.0 <x ≦ 4.0 range) More preferably, in addition to the above formulas (1) to (5), the following formulas (6) and ( It is a range that also satisfies the relationship represented by 7). (6) y ≧ 120x−230 (However, 2.4 ≦ x ≦
3.0 range) (7) y ≧ −10x + 160 (however, 3.0 <x ≦
(Range of 4.0)

For the preparation of the solidifying material, an aqueous suspension containing the above-mentioned particle size fine particle cement as an essential component and an aqueous solution containing an alkali metal silicate as an essential component are prepared in advance and injected at the construction site. Immediately before, these two liquids had a solid content of 1
It is mixed so as to be 0 to 50% by weight. Here, after mixing the cement component and the alkali metal silicate component, water is added to make an aqueous suspension, or either component is made an aqueous suspension or an aqueous solution and then the other components are mixed, When water is further added to adjust the solid content, it takes time to homogenize to the extent that there is no practical problem. If the injection is carried out while spending time for mixing in this way, the flow will stop before it sufficiently penetrates into the surroundings. Therefore, the preparation method as described above is adopted.

Further, not only the solidifying material having the above-mentioned composition but also the drilling hole for allowing various solidifying materials to permeate into the ground around the cut surface in the planned cutting area is It is convenient to form from the upper part to the lower part in the vicinity of the cut surface. That is, if you do this,
Since it is possible to improve the ground by emphasizing the place where collapse is likely to occur due to the cut soil, the pouring effect is efficiently exhibited without waste.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The slope stabilizing method according to the present invention uses an appropriate solidifying material prior to cutting work when reverse winding construction is performed in which a slope that may collapse is cut out stepwise from above. Ground improvement in the planned cut area by injection,
The technical feature is that the cutting work and the anchor body placing work, which are the next steps, are performed after taking measures to reliably prevent the slope from collapsing. As a result, the safety of the construction site is sufficiently ensured and the subsequent work can be efficiently performed. The injection of the solidifying material should be done by inserting a hose into the hole drilled by a rock drilling machine or by inserting an appropriate injection pipe material such as steel pipe or synthetic resin pipe into the hole drilling hole. You can also Furthermore, instead of inserting the pipe material for injection,
It is convenient to use an injection pipe material having a drill bit attached to the tip side because it can be mounted on a rock drill and driven while drilling. Note that these injection pipe materials may be left as they are in the drilled hole, or may be pulled out after injection. Further, in the present invention, as the anchor body for reinforcing the cut surface, deformed bar, rock bolt, ground anchor or the like may be appropriately selected and applied according to the conditions of the construction site and the like. The specific configuration of the construction method will be exemplified below, but the construction is not limited to this.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are explanatory views showing a cross section of a main part in each step in which a construction procedure is shown stepwise in the slope stabilizing method according to the present invention. First, as shown in FIG. 1, the planned cut area 2A of the first stage on the ground slope 1
On the other hand, the drilling hole 4 is excavated along the cut surface 3A from an upper position near the upper end of the cut surface 3A, and the injection pipe 5 is installed therein. Next, the solidifying material 6 is injected from the base end side of the injection pipe 5 and diffused and permeated from the inner wall surface of the drilled hole 4 into the surrounding ground to improve the ground around the cut surface 3A.

The solidifying material 6 used in this embodiment is
A two-component reaction type ground improvement material composed of an aqueous suspension containing fine particle cement having an average particle size of 6 μm or less as an essential component and an aqueous solution containing an alkali metal silicate as an essential component. It is used in a mixed state so that the content of the component is 10 to 50% by weight. The solidifying material 6 having such a composition has a high permeability to the ground and has a property of reacting and solidifying in a short time, and has an effect of solidifying and reinforcing the surface layer portion of the soft ground in a very short time.

A hollow self-piercing lock bolt is used for the injection pipe 5 of the above embodiment. Then, the solidifying material 6 passes through the inside of the hollow portion through the injection adapter 7 and the hose 8 which are connected to the base end side, and flows out into the drilled hole 4 from the bit 5a attached to the tip. At this time, the entrance of the drilled hole 4 is sealed with an appropriate blocking material with the air vent tube inserted. Therefore, the solidifying material 6 extruded from the tip side spreads throughout the drilled hole 4, further penetrates and diffuses from the inner wall surface of the drilled hole 4 to the surrounding ground, and solidifies there. As a result, the ground around the cut surface 3 is surely improved.

The method of injecting the solidifying material composed of the two liquids may be appropriately selected depending on the composition, conditions for improving the ground, working environment and the like. Specifically, for example, the one-shot method, the 1.5-shot method, and the two-shot method, which are used when mixing and injecting the injection material by a normal ground injection method, are suitable, and these have less time loss. , There is an advantage that it can be used for injection immediately after manufacturing.

The one-shot method is a method of injecting from a single injection pipe. An aqueous suspension containing fine particle cement as an essential component and an aqueous solution containing an alkali metal silicate as an essential component are combined with a grout mixer or the like. Mix to prepare a liquid solidifying material. Then, this liquid consolidating material is sucked from the suction port of the grout pump, and pressure-fed to the injection pipe from the discharge port.

Next, the 1.5-shot method is a method in which two liquids are separately fed under pressure and joined together immediately before injection to be mixed. That is, the aqueous suspension and the aqueous solution are respectively prepared by a grout mixer or the like, and the aqueous suspension and the aqueous solution are sucked through the respective suction ports of a grout pump having two suction ports and two discharge ports. Then, these two liquids are respectively discharged to a Y-shaped injection adapter, and these are mixed at a Y-shaped portion to form a solidifying material liquid, which is pressure-fed to an injection pipe.

Further, in the two-shot method, an injection pipe having a double structure is used, and the two liquids are mixed in the ground by flowing through separate flow paths. That is, the aqueous suspension and the aqueous solution are respectively prepared with a grout mixer or the like,
An aqueous suspension and an aqueous solution are sucked from each suction port of a grout pump having two suction ports and two discharge ports, and each liquid is discharged from each discharge port into each flow path of the injection pipe for injection. Both liquids are mixed and used when discharged from the pipe.

In this way, in the first cut planned area 2A, the ground around the cut surface 3A is improved, and then the cut planned area 2A is excavated as shown in FIG.
In the embodiment, the self-drilling rock bolt is used as the injection pipe 5, so that the reinforcing effect as the anchor body is also expected. Therefore, a cap 9 for rust prevention is attached to the head of the injection pipe 5. If only the function as an injection tube is desired, such a cap 9 is unnecessary. It should be noted that the injection pipe 5 may be removed after the injection of the solidifying material 6, and in this case, it does not hinder the work when excavating including the drilled hole 4. Further, when a synthetic resin or rubber is used, it is the same even if it is left as it is. Then, subsequently, as shown in FIG. 3, a simple protective covering material 10 such as a lath wire mesh or expanded metal is laid on the exposed surface of the cut surface 3A. The protective covering material 10 may be appropriately installed depending on the situation of the site, and like the cap 9, is not an essential requirement of the present invention.

Next, as shown in FIG. 4, the anchor body 11 is inserted from the cut surface 3A toward the ground, and the above-mentioned binding material 6 used for ground improvement is filled around the anchor body 11. Fix it on the ground. The anchor body 11 used in the example is a self-piercing lock bolt similar to the injection tube 5. The settlement is
It is carried out by injecting the solidifying material 6 into the drilled hole through the hollow portion of the anchor body 11 as in the case of ground improvement. The fixing material 6 is preferably used as the fixing material of the anchor body 11 due to its characteristics, but any suitable grout material that is generally used will not cause any problems. Furthermore, the anchor body 1
An appropriate pressure bearing plate 12 is attached to the projecting portion of 1, and the protective covering material 10 laid earlier is fixed by being pressed. Here, the cap 9 for rust prevention is also attached to the head of the anchor body 11. Subsequently, the injection pipe 5 is similarly driven from the lower end of the cut surface 3A to improve the ground around the cut surface 3B in the second cut planned area 2B. When constructing the injection pipe 5 for the second stage, it is often installed at an acute angle to the cut surface 3A, so it is convenient to use an appropriate angle adjustment washer 13 together.

In FIG. 5, the planned cutting area 2B of the second step is cut from the state of FIG. 4, the anchor body 11 for pressing the cut surface 3B is similarly fixed, and the third step is further fixed. The injection pipe 5 is installed inside the cut surface 3C in the planned cut area 2C, and the peripheral portion of the injection pipe 5 is improved by the solidifying material 6.

As described above, the ground improvement of the planned cut area by the injection pipe 5, the cutting work, and the placement of the anchor body 11 are sequentially repeated from the top of the planned excavation line to the bottom of the planned excavation line to obtain the ground slope. 1 can be created safely and efficiently. In addition, in the above-mentioned embodiment, the natural slope is not limited to the natural slope, and can be applied to the underground excavation sloped wall surface associated with the construction of various structures, and the type of anchor body and its fixing material. It is of course possible to make various modifications within the technical idea of the present invention, such as changing the.

[0025]

As described above, in the slope stabilizing method according to the present invention, in the reverse winding construction in which the ground slope having a possibility of collapsing is cut out stepwise from above, a suitable solidifying material is used before cutting work. After the soil is preliminarily improved in the planned cut area by pouring and measures for surely preventing the collapse of the slope are taken, the next step, the cutting operation and the anchor body placing operation, is performed. As a result, safety at the construction site will be sufficiently ensured, and subsequent work such as anchor body placement work can be efficiently performed, and its practical effects are extremely high. Is large.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a first step of a construction procedure according to the present invention.

FIG. 2 is an explanatory diagram showing the next step of FIG.

FIG. 3 is an explanatory diagram showing a next step of FIG. 2.

FIG. 4 is an explanatory diagram showing the next step of FIG.

FIG. 5 is an explanatory diagram showing the next step of FIG.

[Explanation of symbols]

1 ... Ground slope 2A, 2B, 2C ... Cut area, 3
A, 3B, 3C ... Cut surface, 4 ... Drilling hole, 5 ... Injection pipe, 6 ...
Solidifying material, 7 ... Injection adapter, 9 ... Cap, 10 ... Protective covering material, 11 ... Anchor body, 12 ... Bearing plate, 13 ... Angle adjustment washer

Claims (3)

[Claims] 1. A slope stabilization method for gradually cutting a ground slope from above while reinforcing the ground slope with an anchor body, and preliminarily drilling holes in the ground around a portion to be the cut surface with respect to a planned cut area. The solidification material is infiltrated through it, and the ground is improved based on the solidification, after which the planned cut area is cut out, and the anchor body is placed from the exposed cut surface toward the ground of the ground. The slope stabilization method is characterized in that a slope is constructed by sequentially repeating these series of operations in the planned cut area below. 2. The solidifying material is injected as an aqueous suspension containing fine particle cement having an average particle size of 6 μm or less and an alkali metal silicate as main components and having a solid content of 10 to 50% by weight. The slope stabilizing method according to claim 1. 3. The slope stabilizing method according to claim 1, wherein the drilled hole is formed in the vicinity of a portion to be a cut surface, from its upper portion to a lower portion.