JPH0249821A - Method of recovering horizontality of lightweight building ununiformly settling - Google Patents

Abstract

PURPOSE:To recover the horizontality of a lightweight building which as settled ununiformly, with no noise and vibration by building a lightweight building support underneath the peripheral section of the deepest settling part of the lightweight building, and by building an additional lightweight building support after the lightweight building is set horizontally in its entirety. CONSTITUTION:A chemical agent is filled right below the deepest settling part of a lightweight building H from peripheral section of the deepest setting part so as to obtain a local support force as a ground reaction force for the lightweight building H is excavated, and a soil layer (g'') below a reinforced concrete base (h) is combed off in a grating shape so as to aim at recovering the horizontality of the lightweight building H. Then, a chemical agent is additionally filled in a part where no lightweight building support is built, so as to obtain an additional lightweight building support force.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a construction method for restoring the levelness of a wooden house or other wooden building (hereinafter referred to as a lightweight structure) when it has unevenly settled.

Prior Art and Problems The phenomenon of uneven settlement of buildings is often seen in buildings built on soft ground. Taking as an example the ground in Sapporofu and neighboring municipalities that was opened at the mouth of the Ishikari River, the deep surface layer of these areas is where the Ishikari River has deposited weathering products such as rocks due to its water flow, as shown in Figure 4. There are two types: riverine alluvium (a) and planted soil (if (b)), where waterfront plants in primitive lakes and marshes withered and organic matter decomposed, filling the lakes and marshes (if (b)).Groundwater level (c)
) is usually high, about 0.9 m above the ground level, as shown in the figure. These are the causes of soft ground, and its structure consists of a skeleton of solid soil particles, with the interstices filled with water, air, and organic matter. N value (d) in these soil layers
(Number of blows in standard penetration exam theory) is extremely low at 0 to 5.
It is unlikely that long-term stable ground bearing capacity will be obtained. These areas include the northern part of Sapporo along the Ishikari River basin, Ishikari Town,
The situation covers a wide area, such as Ebetsu City, Tobetsu Town, and Iwamizawa City, and there are countless lightweight structures that were built without taking measures to prevent ground subsidence from the beginning.

Measures to improve uneven settlement of lightweight structures due to ground subsidence as described above can be roughly divided into two main types.

First, for lightweight structures whose concrete foundations were weakly constructed, only the houses were jacked up and kept hollow at about 2 TrL above ground level, and then the concrete foundations left below were dismantled and removed. The method is to build a new high-strength foundation and jack down the house. This means to raise the house, leaving the foundation intact, and then installing water supply and drainage pipes.

Not only would all gas pipes and other equipment be cut, but supplementary materials to replace the foundation would be attached to the waist wall of the house, which would require partial dismantling of the wall. In addition, pile driving is required to obtain new bearing capacity after the foundation is removed, but since some houses are lifted into the air, short piles must be used to connect them.
Pile driving is inefficient and uneconomical. Roughly speaking, work must be carried out in the following steps: pouring a new concrete foundation on top of the pile, lowering the house, connecting water supply and drainage pipes, gas pipes, etc., and finally repairing the waist wall, which makes the entire construction method difficult. has become an inefficient and uneconomic construction method.

Second, for concrete foundations constructed with high strength and high rigidity, a total of 30 to 40 structure weight-bearing piles are driven around the outer periphery of the foundation and in the central part of the building, and these piles are used as supporting reaction force points. This is a construction method in which the foundations and other structures are jacked up, mainly in areas where uneven settlement has progressed, and houses, etc. are returned to level. This construction method is more rational than the former construction method, but it also requires driving 10 or more piles indoors, so it involves partial demolition of the house's floor, ceiling, concrete floor slab, etc. However, it cannot be denied that the pile length used in a house is limited by the height of the ceiling, resulting in poor workability and increased construction costs. In addition, as a final step, after connecting the water supply and drainage pipes, in order to maintain the strength of the load piece support bracket (p'') at the upper end of the pile (p') shown in Figure 3, we fill it with foot protection concrete (p'''). Requires pouring. Although this construction method is considered to be somewhat more rational than the former construction method, there are still things that need to be improved in terms of workability, and from an economic standpoint, it is beyond the level of low-cost repair. There is a disadvantage. In addition, when it comes to pile driving, in urban areas where residential buildings are located close together, methods such as hammer penetration and photo-shooting are severely restricted, making it an outdated construction method that is unsuitable for the times.

By the way, it is clear that the cause of uneven settlement of light and heavy structures is uneven settlement due to consolidation of the surface ground, which is mainly caused by the exclusion of pore pressurized water in the surface ground and water loss. There is. The following three reasons are thought to be responsible for the removal of pressure water from the surface ground pores and the loss of water. Part 1 shows a relationship curve between the degree of consolidation and consolidation time in FIG. 5, and the primary consolidation in the figure is consolidation where the degree of consolidation is less than 100%. 10
0% consolidation refers to a state in which all substances other than soil particles, such as water and air, are removed from the ground that has not been touched by humans (hereinafter referred to as the ground). The term "load consolidation" refers to this primary consolidation, which is less than 100%. Incidentally, in Figure 5, the part where the consolidation density is 100% or more is called secondary consolidation, and is a part where the soil particles themselves have undergone structural deformation and contraction due to a strong consolidation load. be. The shallow layer receives the load of the lightweight structure, drains ground pressure water, reduces pore volume, and undergoes the above-mentioned primary consolidation, causing ground subsidence. The second issue is the spread of public sewerage systems as urban facilities due to the urbanization of Sapporo-type surrounding suburbs. Sewer pipes are laid in a network of shallow layers in the ground, drawing out large amounts of water held in the ground, lowering the groundwater level and promoting consolidation and subsidence of the ground. The third problem is the decline in water levels deep underground due to the pumping of industrial water and drinking water from factory facilities and housing complexes. Due to these factors, in the vicinity of Juhibe, Sapporo, even in vacant land areas, the ground surface causes ground subsidence of 2 to 3α every year, and the uneven subsidence of light and heavy structures occurs at the lowest point of subsidence. In addition to the above ground subsidence, an additional 2 to 3 crs each year
This indicates a degree of consolidation settlement.

In other words, in cases where unequal loads are applied to foundation structures, the parts bearing the greater load sink first, resulting in the observation of unequal settlement of lightweight structures.

The present invention has been made by focusing on the problems of the prior art described above and the fact that the causes of uneven settlement of lightweight structures are thought to be the three mentioned above. Avoid jacking up, and also connect water supply and drainage,
The purpose of this project is to propose a construction method that can restore the levelness of unevenly settled lightweight structures without cutting or separating gas pipes, etc.

Means for Solving the Problems The means achieved by the present invention to achieve the above-mentioned object includes a first step of building a support force for the lightweight structure below the periphery of the lowest part of the unevenly settled lightweight structure; , a second step of leveling the unevenly sunk light structure as a whole, and a third step of building additional light structure support capacity in areas other than the above-mentioned light structure support capacity building area. That's what it means.

Example This will be explained with reference to the drawings.

There are two examples of the first step of building a lightweight structure supporting capacity below the periphery of the R-sinking part of the pumice structure (H) that has settled unevenly. The first construction method is the construction method shown in the first diagram, which uses soil improvement by injecting chemicals from around the lowest part of the lightweight structure (H) to just below the lowest part of the lightweight structure (H), and as a result, the lightweight structure as a ground reaction force This provides local support for object (H). Since this soil improvement method using the chemical injection method is carried out using a chemical injection device, the chemical injection device will be described below. The chemical dosing device (C) is used for dispensing cement-based solidifying material powder (for example, 1
An example is a stirrer (C1) for making an aqueous solution of Earthtite (trade name, manufactured by Nippon Steel Cement Co., Ltd.), and a powerful high-pressure pump (C1) for sending the aqueous solution to the ground under pressure.
250/(discharge pressure of about g/-) (C2
), a high-pressure hose (C4) for the chemical solution that connects this pump and the header (C3') of the hollow drilling rod (C3),
It is generally composed of a well-known hollow drilling rod (C3) to which a chemical solution is supplied while drilling a hole in the ground. Hollow drilling rod (C
To add more information on 3), the rod is configured to have a diameter of 40 to 50 mm, is configured to be rotated by the shaft (C3''), and the header (C3') is designed to maintain watertightness. The hole drilling machine (C
Drilling cutting edge (C3”) by shaft rotation by 3=l+)
drills into the ground. The drilling cutting edge (0) of the drilling rod (C3)
3") is capable of penetrating rocks and reinforced concrete foundations (h>), and has the ability to penetrate at any position.Until the drilling cutting edge (C3") reaches the predetermined depth position, The pump (C2) supplies fresh water to maintain the drilling function of the cutting edge, and only when drilling is completed, the chemical solution (cement-based solidified water solution) prepared by the stirrer (C1) is supplied from the pump (C2) to drill the hole. At the same time, the hollow drilling rod (C3) is rotated and pulled upward to form a high-strength soil improvement section (G). Weak-strength ground improvement is also carried out in the placed area (a).By improving the ground, bending strength and shear resistance are generated in the ground, and these provide support for lightweight structures as ground reaction force. As a second construction method, there is a pile partial support method shown in Figure 3, which is also effective.In other words, a steel spiral pile (P) is installed around the lowest part of the lightweight structure (H).
By screwing in like an earth auger (not shown) using an electric or hydraulic motor (not shown), a stable and reliable partial support force can be obtained without any tension or noise. On the other hand, the support pile (P) screwed into the ground subsidence area is pushed down by the subsidence edge due to ground subsidence in addition to the pile head support load, so the middle and lower end of the pile has a considerable axial compression rate. This may lead to breakage due to
Careful consideration must be given to strength and the number of pieces used.

The second step following the first step described above is to create a lightweight structure (H)
There are two types of means for restoring horizontality: a natural settling means and a settling auxiliary means. The first method is to wait for natural subsidence of the ground without cutting the target structure (H) after the completion of the first step. As mentioned above, ground subsidence of 2 to 31 degrees is observed every year even in vacant land, so for lightweight structures (H) that show unequal settlement of 201, it is necessary to wait for the passage of time of about 6 to 8 years. If so, the levelness will be restored naturally.

The second method is to slightly modify the basement of the target structure (H). As shown in Figure 1, a part of the ground (g') on the side opposite to the lowest part of the lightweight structure (H) is excavated, and a reinforced concrete foundation (h) is dug out from the excavated hole. ) The soil layer (q") below the soil layer (q") is plowed out in rows.In other words, sections that are plowed out and parts that are not plowed out are alternately provided, and consolidation at the above soil layer (g") progresses. After making it easy to
This is a means for backfilling the hole (g') and restoring the levelness of the lightweight structure (H).

Figure 6 shows the results of measuring the sinking rate of soil 11 (Q”) plowed in rows, which is 3.5 to 4.51 times a year.
This indicates that it is possible to restore levelness in approximately 4 to 5 years for the 201 structures with uneven settlement. Clearing the entire surface of the soil layer (0") is dangerous due to the construction method, and attempting to restore levelness in a short period of time will cause cracks and damage to the lightweight structure (H). This is not a good idea as it may cause damage to connected facilities such as water supply and drainage pipes and gas pipes.It is not advisable to restore the levelness of the lightweight structure ()-1) by using the natural settling means or settling auxiliary means described above. However, leveling the entire structure is the end of the second step.

In the third step, the same chemical injection method as in the first step is applied to the parts left behind in the first step, that is, the parts where the lightweight structure support capacity was not built, to add additional light structure support capacity ( (not shown). As mentioned earlier, the hollow drilling rod (
Since the drilling cutting edge (03") of C3) can penetrate even reinforced concrete, it is possible to drill through the reinforced concrete foundation (h) diagonally from the outside without damaging the indoor floor, so it can be used for a wide range of foundations. It becomes possible to inject cement-based solidifying material underneath.

Regarding ground improvement such as peat layer, in the case of the ground which is mainly made up of mineral soil particles (sandy soil, silt, clay, volcanic ash, etc.), injection of cement-based solidifying agent can improve the soil with a high probability. It is known to have a stable ground improvement effect, but
It is also known that the stability of the improvement effect cannot be quantitatively determined for peat layers of ground with low mineral soil particle components, soil layers with high organic matter content, and sludge and sludge that are mainly composed of industrial waste. The model above is even a little stable.

In order to obtain a quantitative ground improvement effect from chemical injection, it was estimated that mixing mineral particles as an additive when mixing cement-based assimilated materials would be effective in improving the solidification effect. Figure 7 shows
This is an example of the results of an assimilation test. The amount of added material is set at a weight ratio of 1:1 to the cement-based solidifying material, and the final age strength is the same for all materials, but the 7-day age compressive strength as an intermediate process I found that there was a clear improvement in this. Although this addition method does not contribute to adding to the ground strength in the medium to long term, it is considered to be effective in the short term for the following reasons. In other words, peat layers and industrial waste layers are chemically quite active, so the solidification reaction is partially chemically inhibited, and the solidification agent is dispersed into the water flow of the ground before solidification occurs. Therefore, early solidification is considered to be useful as a measure to prevent assimilated materials from failing.

Effect of the invention Since the present invention has the above configuration, it is a wooden house.

A rational and economical method for restoring the original purpose of light structures such as wooden warehouses and other wooden buildings without dismantling or damaging parts of their frames and ancillary facilities. You can aim for it.

[Brief explanation of the drawing]

Fig. 1 is a front view schematically showing the horizontality restoration method of the present invention, Fig. 2 is a vertical cross-sectional view taken along the line (2)-(2>, and Fig. 3 is the second method of the first step of the present invention. A schematic front view showing part 2 of the conventional technology, Fig. 4 is an explanatory diagram of the surface and deep parts of the ground in Sapporo City and neighboring municipalities, Fig. 5 is a graph showing the relationship curve between consolidation degree and consolidation time, and Fig. 6 is a diagram of the present invention. A graph showing the soil layer settlement l when using the second method in the second step of the invention, and FIG. 7 is a graph showing an example of the results of a solidification test for sludge, sludge, etc. In the figure, H...Lightweight structure thing

Claims (1)

[Claims] A first step of building a lightweight structure supporting capacity below the lowest part of the unevenly settled lightweight structure, a second step of leveling the entire unevenly settled lightweight structure, and a second step of leveling the unevenly settled lightweight structure as a whole; A method for restoring the levelness of a lightweight structure that has unevenly sunk, the method comprising a third step of building additional lightweight structure support capacity in areas other than the structure support capacity building area.