JPS5848713B2 - Building construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of constructing a building, particularly a method of constructing a building where uneven settlement is expected.

Buildings are firmly and stably supported by the supporting ground through appropriate earthworks, but as buildings grow larger, the underlying supporting ground itself has local compositional differences, resulting in so-called consolidation settlement. Due to these differences, even before many years have passed, differences in the amount of subsidence occur in different parts of the building, resulting in various problems caused by uneven subsidence.

Traditionally, especially in long buildings, structural joints have been installed to avoid the destruction of the structural frame due to stress caused by undue settlement, or the effects of consolidation settlement of the ground have been eliminated through piling construction, ground improvement, etc. was.

However, as buildings have become taller in recent years, there is a large difference in self-weight between high-rise and low-rise parts of superhigh-rise buildings, and even if they are on relatively homogeneous ground, the supporting ground has a large degree of consolidation. Differences have arisen, and uneven settlement, which is different from the one mentioned above, has become a problem.

One way to solve this problem is to directly support the building with a deep support layer, construct pile construction up to such a support layer, match the number of piles between high-rise areas and low-rise areas, and prevent consolidation. This was a method that would not cause uneven settlement.

In the present invention, the hard supporting stratum under the ground is similar to bedrock, and it slopes to one side within the building site, and the thickness of the surface soil causes a difference in the amount of consolidation, which affects the building. This is a solution that was perfected when constructing buildings on ground that is difficult to maintain, and it divides the building into two parts: a part with a solid support layer and a part with a deep surface layer where the bedrock is sloping. The difference in the amount of consolidation between the two parts is determined in advance, and the latter part is set to be shallower than the former by a dimension equal to this difference, and a separation barrier is provided between the two parts to determine the settling behavior of the two parts. The purpose is to insulate structural stress.

This kind of thinking has been used in cases where buildings built on soft ground are being expanded.

In other words, in the conventional area, consolidation settlement has progressed sufficiently and settlement has stopped, and in the expanded area, settling will begin, so in the expanded area, the construction reference plane is moved upward by a dimension equal to the future amount of sedimentation. Traditionally, a structural joint was installed between the two parts of an extension to allow relative displacement, and in short, the phenomenon of consolidation settlement was absorbed by the action of "time" over a long period of time, and during the transition period, both parts The obstacles caused by the level difference in the reference plane were unavoidable.

The present invention deals with the above-mentioned difference in the degree of compaction,
This invention provides a construction method for a building that eliminates the effect of "time", and examples thereof will be described in detail below with reference to the drawings.

In Figures 1 to 3, G is the site ground of building A, and R is solid supporting ground (hereinafter referred to as ``bedrock'').

), E is a surface worker subject to consolidation. Building A above
is divided into a portion AI that is directly supported on the bedrock R and a portion A2 that is supported on the inclined deep bedrock R through the surface soil E.

Note that if the bedrock R' is located at a deeper position, as shown by the two-dot chain line in Figure 1, the entire building A will be supported through the surface soil E1 and E2, but the surface soil As far as the difference in consolidation between E1 and E2 is concerned, they are the same, so for the sake of simplicity, the following explanation will be based on rock R.

Building A also consists of a basement part B made of steel reinforced concrete (SRC) or reinforced concrete IJ-4 (RC), and a ground floor part C made of steel reinforced concrete. Underground parts B1 and A2 correspond to each other.
A separation strip S is provided between B2 and above-ground parts C1 and C2.

The building A is composed of pillars 10, beams 20, bottom slabs 30, floor slabs 40, outer walls 50, and partitions 60 as a frame part.

Reference numeral 51 designates an earth retaining wall made of columnar walls constructed from above ground prior to excavation on the outside of the underground external wall 50.

Site ground G is determined by excavation during geological survey, for example,
The bedrock R is sandstone, the surface soil E is a sandy clay layer, and the layer thickness to be consolidated is 2 to 4 m.Based on this, the consolidation difference between the two parts A and IA2 of building A was determined. dsc! ′
IL is calculated ignoring the subsidence of bedrock R.

By the way, there is a dSc between the two parts AI*A2 of building A.
If uneven settlement of IrL occurs, the distance l between the columns 10.10 of the two equal parts A1 and A2 (Fig. 1), that is, the allowable amount of deformation for the length of the beam 20, will be far exceeded, so the two parts A
1. A separation strip S is provided between the beams 2 and 2 as described above.
0, bottom plate 30, floor plate 40, outer wall 50, etc. have A1 part and A
Insulating parts 20S, 30S, 40S are provided between the two parts, respectively.
, 50S (see Figures 4 to 8, these will be described later), and in this way the A2 part is the bottom plate 30.
Set the bottom surface above dscrrL from the design surface and construct shallowly.

Furthermore, the amount of settlement reached dscrfL in the A2 part of the building A, and a long period of subsidence is required for both the A1 and A2 parts to match in terms of design, which would prolong the construction period and be impractical.

Moreover, when the amount of sedimentation does not proceed as set, the design surfaces of both the divided portions A, , A2 do not become the same plane, and the connection at the separation zone S portion becomes inconveniently sloping.

Therefore, in the present invention, an overload is applied to the A2 portion to shorten the subsidence period.

That is, as shown in FIGS. 2 and 3, by adding the construction wall 61 to the partition 60 and forming a complete peripheral wall on the bottom plate 30 together with the outer wall 50 and the partition 60, the A2
The underground part B2 of the part is constructed into a water tank P, and this water tank P is filled with water to a predetermined depth to obtain an overload amount commensurate with the water depth and have a forced consolidation effect on the ground directly below, for a short period of time. achieve long-term consolidation.

Here, the water tank P is completed as a large water tank by leaving the floor slabs 40 of each floor as they are, connecting the upper and lower parts through staircases and other openings, and performing appropriate water treatment.

The overload due to this water tank method is an increase in its own weight as the construction progresses upwards of the building A2 (on the other hand, the weight loss due to drainage from the water tank P can be freely and easily adjusted).

Moreover, in addition to the weight of the water in the water tank P, if we aim to effectively utilize the dewatering of groundwater due to pumping from the deep well DP, which is located outside of the building A and deeper than the underground part B2,
It is also possible to reduce the pore water pressure in the surface layer E to be consolidated to promote settling of the building.

In the above, the wall body 61 serving as an additional tank wall is the building A.
will be dismantled after construction is completed.

In the building A constructed by the construction method according to the present invention, on the lower surface of the bottom plate 30, approximately 15
t/m, overload; ground pressure of 10t/m" is applied, A
We were able to complete the construction as planned by setting the uneven settlement ds of the two parts to 20 ynm.

By the way, we will now turn to a description of the separation strip S, which is an important means of solving the problem in carrying out the present invention.

Figures 4 to 8 show parts of the separation strip S such as the floor slab 40, beam 20, outer wall 50, bottom slab 30, etc.
When constructing the two parts, as shown in Figs. 4, 5, and 8, sets of earth pressure transmitting members 81, 82; 83, 84 are provided in the A1 and A2 parts, so that the A2 part becomes A1 due to the earth pressure. Avoid getting close to the side.

In FIGS. 4 and 5, the pressure transmitting member 81 is anchored to the floor slabs 40 and beams 20 of the first and second basement floors on the A1 side with one end 81a protruding into the separation strip S. While being fixed horizontally with bolts 85, the other earth pressure transmission member 82 is attached to the floor slab 40 and beam 20 of the first basement floor and second basement floor on the A2 side, with one end 82a attached to the end surface of the earth pressure transmission member 81. The A2 part is brought into contact with the AI side and fixed horizontally with an anchor bolt 85, so that the A2 part can freely sink, thereby preventing the A2 part from approaching the AI side.

In addition, in FIG. 8, the earth pressure transmission member 83 is fixed horizontally to the A1 side at the position of the underground beam 42 between the bottom slab 30 and the floor slab 41 on the lowest floor, while the other earth pressure transmission member 84 is connected to the bottom slab 30. It is fixed to the underground beam 42 on the A2 side between the floor slabs 41 on the lowest floor, and brought into contact with the end face of the pressure transmitting member 83, so that the A2 part can freely settle in the same way as above. Prevent the A2 portion from approaching the A1 side.

Figure 6 shows the frame steel beam 2 of the beam 20 on the upper floors C1 and C2.
This shows the insulating part 20S in 1, and there is no need to consider the tonosho in this part, but until the time when the beam 20 is supplemented with reinforced concrete, the steel frame 21 in the separation zone S part also has its end faces close to each other and is subject to relative movement in the vertical direction. The steel frame temporary joint 88 is provided here.

In other words, the joint plate 22 is one that is officially designed, but the bolts for the actual joint are not used, and the joint is made with a temporary bolt 23, and the diameter of the bolt is smaller than that of the regular bolt to prevent settling in that part. The difference is made to correspond to the difference, and a regular connection is completed with regular bolts before pouring concrete for the insulating part 20S.

The construction of two parts A1 and A2 of building A has been completed, and A
After the two parts have settled by the predetermined amount, each of the above-mentioned insulating parts 20
Concrete 86 such as non-shrinkable concrete is placed on S, 30S, 40S, and 50S to join the two parts A, , and A2 together.

In this case, the reinforcing bars 8γ of each part of the two-part AH s A2 are overlapped with each other in the separation strip S.

On the outer surface side of the separation strip S between the bottom plate 30 and the outer wall 50, a seventh
Water stop plate 8 made of non-vulcanized butyl rubber, etc., as shown in the figure and Fig. 8.
9 to prevent water leakage.

90 is a water-stop iron plate provided on the bottom surface of the bottom plate 30 of the two parts AI and A2, and 91 is a preliminary expansion and contraction fold.

Note that the earth pressure transmission members 81, 82, and 83 are made of post-cast concrete.
1-8 Remove from building A after pouring and hardening in step 6.

Figure 9 shows that the surface soil E2 is sandy clay and its thickness is about 4 m.
This shows an assumed settlement curve of the amount of settlement due to the progress of construction of building A2 and adjustment of overburden load in the case of , and the progress of construction of building A2 and adjustment of overload load are as follows.

[Actual measurement start date]

Construction of 3 underground spaces, overload (water): /t/m, total ground pressure; 3.8 8 t/if [60th day] Construction of 2 basement floors, 1 basement floor, and 1 floor above ground, overall ground pressure ; 10 t/77J [80th day] Added overload (water) to the 3rd basement floor and the 2nd basement floor, total ground pressure: 1 5.3 8 t/m" (90th day) - Basement 2 Add overload (water) to the first floor and the first basement floor, total ground pressure: 1 9.2 6 t/m' Note that 1 in this figure
The dotted chain line is a general expected settlement curve, and as can be seen from the comparison between this and the implementation effect shown by the solid line, a large settlement promotion effect due to overburden load is recognized.

As explained above, in the present invention, a building is divided into two or more parts based on the estimated amount of consolidation of each part of the supporting ground, and corresponding to the difference in the estimated amount of settlement in each part, Since the reference plane of that part is set above the design plane and construction is carried out, the foundation can be built directly without special land works to avoid uneven settlement, and the construction period can be shortened. .

In addition, supplementation of the separation strip can be carried out in parallel with the construction process, and subsequent deformation due to unexpected stress can be kept within the allowable range.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway front view of a building constructed using the construction method of the present invention, Figure 2 is a cross-sectional view of the second basement floor of the building shown in Figure 1, and Figure 3 is a cross-sectional view of the second basement floor of the building shown in Figure 1. A cross-sectional view of the third basement floor,
Figures 4 and 5 are a plan view and a side view showing the state of the earth pressure transmission members installed on the first and second basement floors, Figure 6 is a cross-sectional view showing the insulating parts of the beams, and Figure 7 is the underground outer wall. Figure 8 is a cross-sectional view showing the insulation part of the bottom slab and underground beam.
FIG. 9 is a time-settlement diagram showing an assumed settlement curve of the amount of settlement accompanying the progress of construction of a building and adjustment of the overload load. A... Building, AH s A2... Part, B1, B2... Basement, C1, C2...
...Ground level, G...Site ground, R...
・Bedrock, S... Separation zone, P... Water tank.

Claims (1)

[Scope of Claims] 1. In a construction method for a building in which uneven settlement is expected in the site ground due to the slope of the supporting ground or differences in floors, the building construction method is based on the assumption of the amount of consolidation of each part of the site ground. The building is divided into two or more parts, and the reference plane for each part is set above the design surface according to the difference in expected settlement amount in each part, and separation is made between each part of the divided building. A belt is provided, and an overburden load corresponding to the set settlement amount is applied to each part to forcibly promote consolidation settling of the ground in that part, and when the settling of each part is completed, the separation belt is filled and connected. A construction method for a building characterized by constructing it as an integrated building. 2. A construction method for a building according to claim 1, characterized in that a water tank is provided in a load-bearing part of the building and water is used as the load. 3. The method for constructing a building according to claim 1 or 2, wherein the overload load is gradually reduced and removed as the construction of the upper layer of the building progresses.