Buildings, foundation construction methods, liquefaction prevention methods, and building collapse prevention methods

Abstract

We focus on the behavior of underground water in the ground at the building site and minimize its impact. [Solution] After a water-stopping material is injected into the ground to form a water-stopping layer 3, the site is excavated and root-cut, and a retaining wall 5 is installed. A foundation 1 is constructed with the sheet piles 52 of the retaining wall 5 also serving as part of the formwork, and a building 2 is built on top of it. The water-stopping layer 3 exerts a water-stopping effect on the side wall surfaces of the recessed space formed by the root-cutting. The water-stopping layer 3 surrounds the foundation in a plan view and extends downward from the bottom of the foundation, preventing underground water directly below the foundation 1 from circulating and rising. The sheet piles 52, which also serve as part of the formwork, remain in the ground even after construction of the building is completed.

Description

[Technical Field]

[0001] The invention of this application relates to technology for preventing settlement (including uneven settlement) in buildings, preventing buildings from tilting due to liquefaction, and preventing houses from collapsing due to river erosion. [Background technology]

[0002] In recent years, with the progress of urbanization, there has been an increase in the number of cases where residential and other buildings are constructed on sites with soft ground that has low bearing capacity. When building, the bearing capacity of the ground on the site is measured by boring surveys, etc., and ground improvement work is carried out based on the results. After the ground improvement work, the foundation is constructed, and the building portion is then constructed on top of that. Known methods of ground improvement work include the pile method and the ground replacement method. The pile method involves driving piles into hard ground such as diluvial deposits, which is suitable from the perspective of preventing building subsidence, but it is a large-scale and expensive construction method. Furthermore, in the event of a major earthquake, the piles transmit the earthquake vibrations to the building, which has caused the building to collapse in some cases. This problem is explained in detail in Patent Document 1. In addition to anchor piles, friction piles are also known as pile methods, but they are similarly expensive and suffer from the same problem of transmitting vibrations during a major earthquake.

[0003] Ground replacement ground improvement is a method that does not rely on piles and can be carried out relatively inexpensively. Among these, the publications disclosed in Patent Documents 2 and 3 involve laying resin blocks with openings as structural materials to replace the ground. Compared to ground replacement materials made of expanded polystyrene, this method has the advantage of not being affected by rainfall during construction. Furthermore, the resin blocks can store underground water, which has the advantage of preventing rainwater runoff during heavy rain and providing seismic isolation in the event of an earthquake. For this reason, ground replacement methods using resin blocks other than expanded polystyrene are becoming more widely adopted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7454897 [Patent Document 2] Patent No. 5938454 [Patent Document 3] Patent No. 4210312 Publication Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, the ground replacement method using resin blocks has many advantages and has come to be widely adopted, however, the inventor has found through field surveys and research that there are cases where it is not necessarily sufficient. This point will be explained below. The reason why conventional ground improvement techniques are not always sufficient is that they do not take into account the behavior of underground water. The underground water considered here is the water present in the gaps between soil particles. In many cases, water exists between soil particles, and this water is stable between the soil particles and forms part of the bearing capacity of the ground. When a major earthquake occurs, the water between the soil particles flows out due to the vibration, causing the bearing capacity of the ground to decrease. Water present between soil particles can also form large underground pools such as groundwater veins. When the water from such underground pools flows out between the soil particles due to the vibrations of a major earthquake and reaches the surface, it suddenly reduces the bearing capacity of the ground. This is the liquefaction that occurs during a major earthquake.

[0006] Liquefaction is an extreme example of how underground water can affect the ground, but when constructing a building on a site, it is necessary to fully consider the effects of underground water, even if it does not go as far as liquefaction. This point is explained below. A soil survey reveals that the soil has sufficient bearing capacity, and after the roots are excavated and the foundations are laid, construction of the building begins. However, during construction, the ground may settle slightly due to the weight of the building. This settlement is only a few centimeters, and is uniform, so it is not a problem, but some clients may be concerned about the impact, and architects and construction companies may also view it as an issue.

[0007] This type of subsidence occurs when underground water directly beneath a building flows out. As a building is constructed on a foundation, the overall load on the ground gradually increases. As a result, the underground water directly beneath the foundation is pushed out and flows out to the surrounding area. As a result, the gaps between the soil particles disappear, the ground becomes compressed, and the foundation and building subside. This situation is similar to when you try to make pickles by putting vegetables in a pickle barrel, putting a lid on it, and placing a pickling stone on top, and over time, water gradually rises from around the lid.

[0008] Using the analogy above, since the pickle barrel prevents water from flowing out, the water can only flow upward, floating evenly around the edge of the lid. If there were a small hole in one place on the side of the pickle barrel, water would also flow out from there, causing the water to flow out unevenly and causing the lid and pickle stones to tilt. In terms of a building, this would result in uneven settlement of the foundation or building. This is an extreme case, but if the distribution of underground water becomes unbalanced as a result of the construction of a building, it is thought that liquefaction or a situation similar to liquefaction could easily occur due to vibrations during a major earthquake.

[0009] The above-mentioned underground water outflow is thought to have an impact on neighboring buildings. Let's say a building is being constructed on a certain site. The underground water is distributed evenly on this site, including the adjacent sites. "Evenly distributed" means that the osmotic pressure of the underground water on one site is in balance with the osmotic pressure of the underground water on the adjacent sites, and the underground water is distributed stably. On such sites, root excavation is carried out to construct a building, and then earth retaining structures are installed, followed by the construction of the foundation. When this is done, the area where the root excavation was carried out becomes a void, resulting in an area with zero distribution of underground water. This causes the seepage pressure balance to be lost, and water from the adjacent site to leak out. In fact, when root excavation, earth retaining structures are carried out and foundations are constructed, it is often the case that water from the neighboring site seeps out through the gaps in the earth retaining sheet piles. If the amount of water seeping in from the neighboring site is small, the impact is minimal, but in sites where the ground strength is barely secured by the bearing capacity of the soil, including the distributed underground water, there is a risk that uneven settlement will occur if a large amount of water leaks out.

[0010] The present invention was made based on this awareness of the problem, focusing on the behavior of underground water in the ground at the site of a building, with the aim of minimizing its impact. [Means for solving the problem]

[0011] Based on the above-mentioned awareness of the problem, this specification discloses inventions for a building, a foundation construction method, a method for preventing liquefaction, and a method for preventing building collapse. The building according to the disclosed invention is a structure consisting of a foundation and a building constructed on the foundation. The building is provided with a water-stopping layer formed by injecting a water-stopping material into the ground, and the water-stopping layer is provided along the periphery of the foundation and extends vertically to form a water-stopping wall. Furthermore, the building according to the disclosed invention may have a configuration in which the water-stopping layer is provided on the outside of the foundation and surrounds the foundation in plan view. In addition, the building according to the disclosed invention may have a configuration in which a water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes the area above the lowest depth of the foundation. In addition, the building according to the disclosed invention may have a configuration in which formwork used during construction of the foundation remains between the water-stopping layer and the side of the outer periphery of the foundation, filling the space between the water-stopping layer and the side of the outer periphery of the foundation. In addition, the building according to the disclosed invention may have a configuration in which a water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes the area below the position of the lowest depth of the foundation. Furthermore, the building according to the disclosed invention may have a configuration in which the water-stopping layer is formed so as to extend downward below the outer periphery of the foundation. Furthermore, the building according to the disclosed invention may have a configuration in which the water-stopping layer is formed so as to extend downward from the bottom surface of the outer periphery of the foundation. In addition, the building according to the disclosed invention has a configuration in which a water-stopping layer is provided on the outside of the foundation, and a reinforcing layer is provided below the outer periphery of the foundation, the reinforcing layer being reinforced by injecting reinforcing material into the ground, and the reinforcing layer is provided extending along the outer periphery of the foundation. In addition, the foundation construction method according to the disclosed invention is a foundation construction method for a building, and includes a water stop layer formation process in which a water stop material is injected into the ground in advance to form a water stop layer, a root cutting process in which the site is excavated and root cutting is performed for foundation construction after the water stop layer formation process, and a foundation construction process in which the foundation is constructed after the root cutting process. In this foundation construction method, the water-stopping material injection step is a step of injecting water-stopping material into a region of a predetermined depth so as to surround, in plan view, the horizontal region where root cutting is planned. In addition, the foundation construction method of the disclosed invention may be configured such that the specified depth region includes a region between the position of the lowest depth of the root cutting in the root cutting process and a position shallower than that position. In addition, the foundation construction method of the disclosed invention may be configured such that the specified depth region includes a region between the position of the lowest depth of the root cutting in the root cutting process and a position deeper than that position. The disclosed invention also provides a liquefaction prevention method for a building site, which involves injecting a water-stop material into the ground at a predetermined depth to form a water-stop layer extending downward from the bottom surface of the periphery of the foundation along the periphery of the building foundation, thereby forming a water-stop wall and preventing water from flowing out from the ground directly below the building. The disclosed invention also provides a method for preventing building collapse, which prevents buildings located near rivers from collapsing due to river erosion. This method involves injecting a water-stop material into the ground at a predetermined depth to form a water-stop layer that extends downward from the lowest depth of the outer periphery of the foundation along the periphery of the building's foundation, acting as a water-stop wall, which prevents the ground below the foundation from eroding away, thereby preventing the building from collapsing. [Effects of the Invention]

[0012] As explained below, the building according to the disclosed invention has a water-stopping layer formed by injecting a water-stopping material into the ground, and the water-stopping layer is provided along the periphery of the foundation and extends vertically to form a water-stopping wall, so that underground water is stably distributed around or directly below the foundation, thereby preventing the foundation and building from sinking. Furthermore, if the water-stopping layer is provided on the outside of the foundation and the vertical area in which the water-stopping layer is formed includes the area above the lowest depth of the foundation, the water-stopping layer will also have a water-stopping effect on neighboring land during construction, preventing problems caused by a deterioration in the balance of underground water. Furthermore, if the water-stopping layer is provided on the outside of the foundation and the vertical area where the water-stopping layer is formed includes an area below the depth of the foundation's lowest point, water is prevented from rising around the foundation from a position directly below the foundation. Therefore, even if the load increases due to the construction of a building, the underground water remains directly below the foundation, so subsidence of the foundation or building does not occur. Furthermore, by forming the water-stopping layer so that it extends downward below the outer periphery of the foundation, it is possible to prevent water from rising around the foundation from a position directly below the foundation. Therefore, even if the load increases due to the construction of the building, the underground water will remain directly below the foundation, preventing the foundation or building from sinking. Furthermore, by forming the water-stopping layer so that it extends downward from the bottom surface of the outer periphery of the foundation, it is possible to prevent groundwater from rising around the foundation from a position directly below the foundation. Therefore, even if the load increases due to the construction of the building, the groundwater will remain directly below the foundation, preventing the foundation or building from sinking. In this case, because the water-stopping layer is in contact with the bottom surface of the outer periphery of the foundation, it is more effective in preventing groundwater from flowing out from directly below the ground. In addition, a reinforcing layer is provided below the outer periphery of the foundation, where the ground is reinforced by injecting reinforcing material into the ground, and the reinforcing layer is provided extending along the outer periphery of the foundation.This configuration achieves the effect of preventing uneven subsidence by injecting reinforcing material that takes into account the factors that cause uneven subsidence of the building, so only the minimum amount of reinforcing material required needs to be injected, and the effect of preventing uneven subsidence can be achieved at low cost. Furthermore, according to the liquefaction prevention method of the disclosed invention, by injecting a water-stop material into the ground to a predetermined depth, a water-stop layer is formed that extends downward below the periphery of the foundation of the building and along the periphery of the foundation, and liquefaction is prevented by suppressing the outflow of water from the ground directly below the building, so the amount of water-stop material required is significantly reduced, making liquefaction prevention extremely inexpensive.Furthermore, this method can be applied to existing buildings, making it an extremely versatile liquefaction prevention method. Furthermore, according to the disclosed method for preventing building collapse of the invention, by injecting a water-stopping material into the ground in a predetermined depth region, a water-stopping layer is formed that extends downward from the lowest depth position of the outer periphery of the foundation along the periphery of the building's foundation, acting as a water-stopping wall, and the action of the water-stopping wall prevents the ground below the foundation from eroding, thereby effectively preventing the collapse of buildings in the event of a disaster in which the soil is gradually eroded by river flooding. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic front cross-sectional view of a building according to a first embodiment. [Figure 2] FIG. 2 is a schematic plan cross-sectional view of the underground portion of the building in FIG. 1. [Figure 3] 1 is a schematic diagram showing a method for constructing a building according to a first embodiment and a method for constructing a foundation according to the first embodiment. [Figure 4] FIG. 10 is a schematic front cross-sectional view showing the effect of forming a water blocking layer. [Figure 5] FIG. 10 is a schematic front cross-sectional view showing the effect of forming a water blocking layer. [Figure 6] FIG. 10 is a schematic plan view showing an example in which the water blocking layer does not surround the entire area by 360°. [Figure 7] FIG. 10 is a schematic front cross-sectional view of a building according to a second embodiment. [Figure 8] FIG. 4 is a schematic plan view showing the horizontal shape of a reinforcing layer. [Figure 9] FIG. 10 is a schematic front cross-sectional view showing a method for constructing a building according to a second embodiment and a method for constructing a foundation according to a second embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional front view showing the effect of a reinforcing layer in the second embodiment. [Figure 11] 1 is a schematic cross-sectional front view showing a liquefaction prevention method according to an embodiment. [Figure 12] FIG. 10 is a front cross-sectional schematic view showing the effect of the liquefaction prevention method of the embodiment. [Figure 13] 1 is a schematic front cross-sectional view showing a method for preventing building collapse according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, modes (embodiments) for carrying out the invention of this application will be described. First, an embodiment of the invention of a building and an embodiment of the invention of a foundation construction method will be described. Figure 1 is a schematic front cross-sectional view of a building of the first embodiment. As shown in Figure 1, the building of this embodiment comprises a foundation 1 and a building 2 constructed on the foundation 1. The building 2 is assumed to be a residential building for which subsidence can be a particular problem. More specifically, the building 2 is assumed to be a detached house or a low-rise or mid-rise apartment building. The structure of the building 2 may be wooden, lightweight steel frame, reinforced concrete (RC), or the like. The foundation 1 is a mat foundation, and in this example, it is a skeleton that forms a pit. In this embodiment, one of the features of the building of the embodiment is that the structures used for earth retaining also serve as formwork for the foundation work, and these remain. That is, as shown in FIG. 1, earth retaining support materials (H-beams, etc.) 51 and sheet piles 52 remain around the periphery of the foundation 1. It is also possible to provide a ground replacement layer formed by laying resin blocks under the foundation 1; for this, see Patent Documents 1 to 3.

[0015] A major feature of the building of this embodiment is that the water blocking layer 3 surrounds the periphery of the foundation 1. This will be explained in more detail with reference to Figure 2. Figure 2 is a schematic plan cross-sectional view of the underground portion of the building of Figure 1. As shown in Figure 2, the water stopping layer 3 extends circumferentially along the outline of the area occupied by the foundation 1 (shown by the dashed-dotted line). The "area occupied by the foundation" refers to the area occupied by the foundation as a whole, and in the case of a continuous foundation, it refers to the outline of the outermost part. In this embodiment, the water stopping layer 3 surrounds the periphery of the foundation 1 360°, but this is not required and the water stopping layer 3 may surround less than 360°.

[0016] The water stopping layer 3 is formed by injecting a water stopping material. The water stopping material is injected into the ground and solidifies to form the water stopping layer 3. Although it is called solidification, it may not completely harden and may remain in a gel state. The water stopping layer 3 extends not only horizontally but also vertically (depth direction). Hereinafter, the region in which the water stopping layer 3 extends vertically will be referred to as the depth region. In this embodiment, the depth region of the water stopping layer 3 is a region that spans the lowest position of the foundation 1. That is, the water stopping layer 3 is above the lowest position of the foundation 1 at its shallowest point (shallower than the lowest position), and below the lowest position of the foundation 1 at its deepest point (deeper than the lowest position).

[0017] The following describes a method for constructing a building according to an embodiment. The following description includes a description of a foundation construction method according to a first embodiment. Figure 3 is a schematic diagram showing the method for constructing a building according to the first embodiment and the foundation construction method according to the first embodiment. When constructing a building according to the embodiment, a water-stopping material injection process is first carried out prior to the construction of the foundation 1. The water-stopping material injection process is a process of injecting water-stopping material to a predetermined depth area around the area where the foundation 1 is to be constructed. In FIG. 3(1), the area where the foundation 1 is to be constructed is surrounded by a dotted line. Hereinafter, this area will be referred to as the planned foundation construction area. The planned foundation construction area is the spatial area that the foundation 1 will occupy when constructed.

[0018] As shown in Figure 3 (1), the water-stop material injection process is carried out by inserting an injection pipe 41 into the ground and discharging the water-stop material from the bottom end of the injection pipe 41. The injection pipe 41 is often inserted after drilling a narrow hole with a boring rod. The injected water-stop material penetrates between the soil particles to a certain extent and then hardens, forming a water-stop layer 3. The injection method is often a double-pipe strainer method (single-phase or multi-phase) in which the boring rod is also used as the injection pipe 41, but a double-pipe double-packer method in which boring (hole drilling) and injection are performed separately is also sometimes used.

[0019] Sodium silicate (water glass) can be used as a water-stop material, such as No. 3 sodium silicate (JIS K 1408). Water-stop materials are typically used with a hardener (hereafter referred to as a water-stop hardener). For example, when No. 3 sodium silicate is used as the base material, the hardener can be an inorganic acid (dilute sulfuric acid, phosphoric acid, etc.), a metal salt (sodium bicarbonate, potassium bicarbonate, bisulfate, etc.), or an organic solvent such as ethylene carbonate or glyoxal. In addition, cement or hydrated lime can also be used as a water-stop hardener for suspension-type water-stop materials. A more specific example is a mixture of equal amounts of water glass and Mitsubishi Chemical Infratec Corporation's NTite RS hardener ("NTite" is a registered trademark of the company). For example, 70 liters of No. 3 sodium silicate are diluted with 130 liters of water, and 21 kg of NTite is dissolved in 200 liters of water. The two are then mixed immediately before injection.

[0020] Although not shown in detail in Fig. 3(1), a chemical injection device is used to inject the water-stopping material. The chemical injection device has an injection pipe 41 attached to the tip of a pipe connected to a container that stores the water-stopping material, and is equipped with a pump that pressurizes the water-stopping material, a controller that controls the injection time and injection pressure, etc. The osmotic pressure of the water-stopping material caused by the pump acts in all directions from the tip of the injection pipe 41, causing the water-stopping material to spread between the soil particles in an almost spherical (bulb-like) shape and then harden. Therefore, the water-stopping layer 3 becomes a layer in the form of a series of bulb-shaped portions. For the sake of convenience, the portion 31 of the water-stopping layer 3 that has hardened and spread in a bulb-like state will be referred to as the bulb portion below. Furthermore, the position 42 on the ground surface where the injection pipe 41 is inserted will be referred to as the injection point. The injection point 42 is indicated by a ● in Figure 2.

[0021] If the height of the bulb portion 31 formed in one injection occupies the required depth range, the injection of the water-stopping material at one injection point 42 is complete. However, in many cases, the height of the required depth range exceeds the height of the bulb portion 31. In such cases, multiple injections are performed at one injection point 42. That is, as shown in FIG. 3(2), the tip of the injection pipe 41 is positioned at different depths to inject the water-stopping material. Typically, one injection is performed with the lower end of the injection pipe 41 at the deepest position, and then the lower end of the injection pipe 41 is raised a predetermined distance above (to a shallower position) to inject the water-stopping material a second time. In this manner, the water-stopping material is injected at gradually shallower positions to form the water-stopping layer 3 in the required depth range. While injection at gradually deeper positions is possible, injection at gradually shallower positions is preferable. This is because if the hardening rate is fast, the water-stopping material may harden at the shallower position where it was first injected, hindering the lowering of the injection pipe 41.

[0022] After the water-stopping material has sufficiently hardened and the water-stopping layer 3 has been formed, excavation is carried out as shown in Figure 3 (3). The excavation is carried out by digging an area slightly larger than the area set as the area where the foundation will be constructed to a specified depth. At this time, a part of the water-stopping layer 3 (towards the center of the building 2 to be constructed) is slightly removed. Then, as shown in Figure 3 (4), a retaining wall 5 is constructed. The retaining wall 5 is constructed by driving support materials 51 such as H-beams and fitting sheet piles 52 into the wall. The retaining wall 5 is constructed so as to cover the exposed surface (side surface) of the water-stopping layer 3 that has been removed.

[0023] Next, as shown in Figure 3 (5), the foundation 1 is constructed. After necessary ground work, such as tamping the excavated soil and laying crushed stone, the foundation (mat foundation) 1 is constructed. In this case, the support materials 51 and sheet piles 52 constructed as the earth retaining wall 5 are also used. That is, concrete is poured using the sheet piles 52 as part of the formwork, and after curing, the foundation 1 is completed. Then, after the foundation 1 is constructed, the skeleton is built and the building 2 is constructed. In this example, the support materials 51 and sheet piles 52 remain even after the foundation 51 is completed, and remain even after the construction of the building is completed, becoming underground buried structures. Note that when the building is completed, the ground surface is often slightly higher than when the earth retaining wall 5 was formed, with the topsoil added. If the top of the foundation 1 is higher than the top of the earth retaining wall 5, additional formwork is used in this area, but this is removed after the foundation 1 is constructed.

[0024] In a building constructed in this manner, the water blocking layer 3 restricts the movement of underground water directly below the foundation 1, providing various benefits. This will be explained below with reference to Figures 4 and 5. Figures 4 and 5 are schematic front cross-sectional views showing the benefits of forming the water blocking layer 3. Without the water-stopping layer 3, as shown schematically in Figure 4(1), as construction of the building 2 progresses and the load increases, underground water W will seep out, surround the foundation 1, and rise. This may cause the foundation 1 and the building 2 above it to settle by several centimeters. On the other hand, when the water stop layer 3 is present, as shown schematically in Figure 4(2), the water stop layer 3 blocks and prevents the outflow of underground water W from directly below the foundation 1. Therefore, even when the load on the building 2 increases, the underground water W is stably distributed directly below the foundation 1. This prevents the foundation 1 and the building 2 from sinking.

[0025] Furthermore, suppose that liquefaction or a situation close to liquefaction occurs in the neighboring land during a major earthquake. That is, suppose that a considerable amount of underground water flows out of the neighboring land, causing an imbalance in the underground water balance. Even in this case, the movement of underground water is restricted by the waterstop layer 3 directly below the building of the embodiment, so the underground water does not flow out, and liquefaction or the resulting sinking of the building 2 does not occur. Note that, just as in the neighboring land, rising pressure of water due to vibrations occurs directly below the foundation 1 of the building of the embodiment, but because the waterstop layer 3 restricts the water from flowing around and rising, the water remains directly below the foundation 1 and does not reach the ground surface. This point will be discussed in more detail in the explanation of the embodiment of the liquefaction prevention method described below.

[0026] Furthermore, in the building of this embodiment, the water-stopping layer 3 is effective on the neighboring land during construction, preventing problems caused by the deterioration of the groundwater balance. That is, as shown in Figure 5, when root cutting and earth retaining 5 are performed, the space created by the root cutting becomes a space where there is no groundwater, and the seepage pressure of the groundwater W of the neighboring land acts. However, because the water-stopping layer 3 is present, the groundwater of the neighboring land does not flow out, and the groundwater balance of the neighboring land does not deteriorate. Therefore, even if the ground strength of the neighboring land is barely secured by the bearing capacity of the soil including the distributed groundwater, uneven settlement, etc. will not occur on the neighboring land.

[0027] Formation of the water stop layer 3 by injecting a water stop material as described above is often performed in the field of civil engineering work. For example, in tunnel construction, when digging a tunnel below an underground water vein, a construction method is adopted in which the water stop layer 3 is formed across the underground water vein, and then the bottom of the water stop layer 3 is excavated. The building and foundation construction method of the embodiment can be said to be the application of such civil engineering technology to the field of architecture. In this case, it is based on the unique idea of ​​forming the water stop layer 3 vertically (in the vertical direction) to restrict the lateral flow of water.

[0028] As described above, in the building of the embodiment, the formed water blocking layer 3 extends to a depth range and acts as a water blocking wall underground, so to speak. Therefore, the above-mentioned effects can be obtained. The preferable depth range of the water blocking layer 3 having such effects will be further explained below. As described above, the water stopping layer 3 occupies a depth region underground that extends in the extension direction from a certain depth position. In this case, it is preferable that the depth region of the water stopping layer 3 occupies the depth position of the lowest part of the foundation 1. Hereinafter, for convenience of explanation, the depth position of the lowest part of the foundation 1 will be referred to as the lowest foundation level.

[0029] The depth region of the water-stopping layer 3 includes the region above the lowest level of the foundation. This region is called the upper region. As can be seen from the above explanation, the upper region mainly functions to prevent underground water from flowing out from adjacent land after root cutting. The upper region may reach the ground surface, but even if it does not reach the ground surface, the water-stopping function is sufficient. The distance from the top end of the upper region to the ground surface (shown as D1 in Figure 1) is preferably, for example, about 50 cm to 200 cm.

[0030] The depth region of the water-stopping layer 3 includes a region below the lowest level of the foundation. Hereinafter, this region will be referred to as the lower region. The lower region mainly functions to prevent underground water from flowing out laterally from a position directly below the foundation 1, and to prevent underground water from flowing in from the side to a position directly below the foundation 1. To achieve this function, the length of the lower region (shown as D2 in Figure 1) is preferably, for example, about 50 cm to 300 cm. However, D2 is appropriately selected depending on the ground conditions. D2 is made longer in ground with a relatively large amount of underground water, and also in ground with a considerable amount of groundwater nearby.

[0031] As shown in FIG. 1, the lower region is in contact with the foundation 1 at its bottom. This structure is particularly suitable for preventing underground water from rising (seeping out) from directly below the foundation 1. Regarding the side surfaces, if the foundation 1 is constructed using sheet piles 52 as formwork as described above and the method of leaving the piles in place after construction is not adopted, a gap will inevitably form between the water-stopping layer 3 and the foundation 1. This gap is filled with surplus soil, but it is desirable that the gap (the distance between the outer side surface of the foundation 1 and the water-stopping layer 3) be small. Specifically, the gap should be 20 cm or less, preferably 10 cm or less, and even more preferably 5 cm or less.

[0032] The above has been a description of the depth region of the water stopping layer 3, but the water stopping layer 3 also extends horizontally and occupies a horizontal region (horizontal region). The horizontal region of the water stopping layer 3 will be described below with reference to FIG. 2. As described above, when the water-stopping material is injected, it spreads and hardens in a bulbous shape. Therefore, as shown in Fig. 2, the bulbous portion 31 of the water-stopping material is approximately circular in plan view, spreading out from the injection point 42. Therefore, the water-stopping layer 3 is made up of a series of approximately circular bulbous portions 31 connected in a circumferential manner in plan view.

[0033] Ideally, the bulb portions 31 should be in contact with each other in the circumferential direction (horizontal direction) with no gaps. However, gaps between the bulb portions 31 do not often cause practical problems. However, if the gap exceeds 50% in the direction in which the bulb portions 31 are connected (circumferential direction), the water-stopping layer 3 may not function properly. Therefore, it is preferable to keep the gap below 50%. Specifically, if the average width of each bulb portion 31 in the direction in which the bulb portions 31 are connected is W and the spacing between the bulb portions 31 is D3, D3 is preferably W / 2 or less. While variations in D3 are inevitable depending on the position, it is preferable to keep it below W / 2 at all positions. It is more preferable that D3 be 40% or less of W, and even more preferable that D3 be 20% or less of W. D3 can be adjusted by changing W, while W can be adjusted by changing the injection pressure and injection time of the water-stopping material.

[0034] The earth retaining wall 5 is constructed by driving a large number of support materials 51 into the ground at equal intervals and bridging the gaps between the support materials 51 with sheet piles (not shown in Figure 2), and as shown in Figure 2, it is preferable to select the injection points 42 so that each bulb portion 31 reliably covers the driving position of the support material 51. Specifically, it is preferable to select the injection points 42 at the same position as the driving position of the support material 51 or a position slightly inside. The injection points 42 may be located outside the driving position of the support material 51, but if they are located too far outside, the bulb portions 31 may reach the ground of the neighboring land if the property boundary is close, so it is better not to set them too far outside.

[0035] The reason for setting the injection point 42 at or near the driving position of the support material 51 is that the support material 51 can become a route for underground water to flow out. When the support material 51, such as an H-beam, is driven to form the earth retaining wall 5, if sufficient earth pressure is not applied to the support material 51 from the surrounding area or if a small gap is formed, water is likely to flow through the gap. This water comes from water below the excavation base or from the neighboring land. If a large amount of water rises along the support material 51, subsidence is likely to occur when the load increases during the construction of the foundation 1 and the building 2. Furthermore, if the support material 51 attracts underground water from the neighboring land and a large amount of underground water from the neighboring land flows out along the support material 51, accidents such as uneven subsidence on the neighboring land are likely to occur.

[0036] To avoid such problems, when the earth retaining wall 5 is formed by driving the support members 51, measures are taken to prevent underground water from rising, such as tamping the support members 51 so that sufficient earth pressure is applied to the rear of the support members 51 (the side opposite the sheet piles 52) or injecting cement milk into the rear of the support members 51 to solidify it. However, if the measures are insufficient or not taken at all to reduce costs, the above-mentioned problems persist, and the cost of repairs is likely to far exceed the cost savings. This problem also occurs when the earth retaining wall 5 is removed after the foundation 1 is constructed, but in this embodiment, a construction method is adopted in which the earth retaining wall 5 remains, so the problem may persist even after the building is completed. In the building of the embodiment, taking these points into consideration, the injection point 42 is set at or near the driving position of the support material 51 so that the periphery of the support material 51 (the periphery in plan view) is completely and reliably surrounded by the bulb portion 31. The vicinity is, for example, within 50 cm, more preferably within 30 cm, of the driving position of the support material 51. Note that the structure in which the periphery of the support material 51 is surrounded by the water stopping layer 3 also has the effect of preventing corrosion of the support material 51 when the support material 51 is made of metal such as H-beam.

[0037] As mentioned above, the water stopping layer 3 does not need to surround the periphery of the foundation 1 360°. This point will be explained with reference to Fig. 6. Fig. 6 is a schematic plan view showing an example in which the water stopping layer 3 does not surround the periphery 360°. For example, as shown in Figure 6, if site 91 faces road 92 and the other side of road 92 is filled with fields or other land with no residential buildings, there is basically no need to consider the impact of groundwater inflow from neighboring land during root cutting on the road 91 side, which could lead to a deterioration in the groundwater balance. Furthermore, if building 2 is planned to be built close to road 92 and the ground on the road 92 side has been reinforced by compaction or other methods, and groundwater outflow is expected to be low, there is little need to restrict groundwater outflow from directly below foundation 1. In such a case, as shown in Figure 6, no waterstop layer 3 is formed on the road 92 side, and the waterstop layer 3 may not surround foundation 1 in this area. Additionally, if the load distribution of building 2 is uneven and there are areas (edges) where the load is light, it may be possible to configure those areas without providing a waterstop layer 3.

[0038] However, in the case of narrow land, etc., when the distance from the excavated area to the road (public road) is short (when the road is close), it is possible to install a water-stop layer 3 to protect the road portion. According to the inventor's actual experience, when excavating near the road and constructing an earth retaining wall 5, the outflow of underground water can weaken the ground directly below the road, causing accidents such as the collapse of structures such as gutters. Therefore, from the perspective of road protection, it is possible to install a water-stop layer 3 also in the area facing the road. This can also be considered an invention of a method for protecting structures under the road.

[0039] Next, a description will be given of a building and a foundation construction method according to a second embodiment. Fig. 7 is a schematic cross-sectional front view of a building according to the second embodiment. The building of the second embodiment is provided with a reinforcing layer 6 in which the ground is reinforced by injecting a reinforcing material, in addition to the water-stopping layer 3. A major feature of this building is that the reinforcing layer 6 is provided along the contour of the horizontal area occupied by the foundation 1, and the reinforcing layer 6 supports the foundation 1 from below.

[0040] More specifically, a non-aqueous glass suspension type reinforcement can be used. For example, a blend of Portland cement, Sanko Hard AQ2 series 5-second accelerator and 5-second hardener from the same series manufactured by Sanko Colloid Chemical Co., Ltd. can be used. An example of a blend per 400 liters would be to mix 25 kg of Portland cement with 6 kg of Sanko Hard AQ2-5-second accelerator to make 200 liters of liquid A, and then dissolve the Sanko Hard AQ2-5-second hardener in water to make 200 liters of liquid B, and then mix liquid A and liquid B immediately before injection.

[0041] 8 is a schematic plan view showing the horizontal shape of the reinforcing layer 6. The reinforcing layer 6 is also formed by injecting a reinforcing material as a chemical solution, and the injection is performed by inserting an injection tube 41 and applying pressure. Therefore, similarly, the reinforcing material penetrates into the reinforcing material during injection, forming bulbous portions 61. Therefore, the reinforcing layer 6 is a layer formed by a series of bulbous portions 61 made of hardened reinforcing material in the horizontal direction. In this case, it is desirable that the bulb portions 61 are in contact with each other in the horizontal direction as shown in Figure 8, but they may be spaced apart. If the average width of each bulb portion 61 seen in the direction in which the bulb portions 61 are connected is W2 and the distance between adjacent bulb portions 61 is D4, it is preferable that D4 be W2 / 2 or less.

[0042] The method for constructing a building according to the second embodiment and the method for constructing a foundation according to the second embodiment will be described with reference to Fig. 9. Fig. 9 is a schematic front cross-sectional view showing the method for constructing a building according to the second embodiment and the method for constructing a foundation according to the second embodiment. When constructing a building according to the second embodiment, a chemical injection process is performed in advance, as in the first embodiment. First, chemical injection is performed for the reinforcing layer 6 to be formed at a deeper position. That is, as shown in FIG. 9(1), an injection pipe 63 is driven into an injection point 62 set inside the boundary line of the area where the foundation 1 is to be constructed in the design, and reinforcing material is injected. The injected reinforcing material hardens after a scheduled time has elapsed to form the reinforcing layer 6. If the reinforcing layer 6 cannot be formed to the required height with a single injection, the reinforcing material is injected at a different height from the same injection point 62. Note that the highest (shallowest) position within the depth region of the reinforcing layer 6 is the bottom of the foundation 1. However, if a ground replacement layer is formed using resin blocks or the like, the bottom of the ground replacement layer will be the highest point of the reinforcing layer 6.

[0043] In this way, the reinforcing material is injected at each injection point 62, thereby forming a circumferential reinforcing layer 6. Next, as shown in FIG. 9(2), the chemical solution for the water-stopping layer 3 is injected. This is the same as in the first embodiment. As a result, the water-stopping layer 3 is formed in a circumferential shape. When forming the water-stopping layer 3, the same material as the reinforcing layer 6 may be used, and the same injection pipe may also be used. Thereafter, as shown in Figure 9(3), the area where the design indicates that the foundation 1 will be constructed is excavated. Then, as shown in Figure 9(4), support materials 51 are driven in and sheet piles 52 are laid across them, and an earth retaining wall 5 is constructed. Thereafter, as shown in Figure 9(5), the foundation 1 is constructed. At this time, the sheet piles 52 also serve as part of the formwork for the foundation 1. Even after the foundation 1 is completed, the support materials 51 and the sheet piles 52 are left in place and not removed. Note that, prior to the construction of the foundation 1, a ground replacement layer is created by laying a large number of lightweight ground replacement materials such as resin blocks, if necessary, and the foundation 1 is constructed on top of that. Thereafter, the framework is constructed on the foundation 1 as usual, and the building 2 is built.

[0044] In the building and foundation construction method of the second embodiment, the reinforcing layer 6 has the effect of achieving sufficient ground improvement effects while realizing low costs. This point will be explained with reference to Fig. 10. Fig. 10 is a front cross-sectional schematic diagram showing the effect of the reinforcing layer 6 in the second embodiment. Ground reinforcement using chemical grouting is often performed in the field of civil engineering, such as when constructing bridge piers for highways and bridges. This type of ground reinforcement using the chemical grouting method can also be used in the construction of residential buildings such as apartment buildings, but the drawback is that it is a high-cost method.

[0045] The reason for the high cost is that it directly uses technology from the civil engineering field without considering its relationship to the building. In other words, chemicals are injected into the ground over the entire site where the building will be constructed, forming a cross-sectional reinforcing layer. As a result of forming a cross-sectional reinforcing layer over the entire area, a large amount of chemicals needs to be injected, and the number of injection points also increases, resulting in increased labor hours. For this reason, it is considered a high-cost ground improvement technology in the field of construction. On the other hand, in the building and foundation construction method of the embodiment, the reinforcing layer is not formed across the entire structure, but is provided so that it extends along the contours of the horizontal area occupied by the foundation 1. This structure is significant in that it can obtain a sufficient effect of preventing uneven settlement by injecting the minimum amount of chemical solution necessary, taking into account the causes of uneven settlement of the building.

[0046] As is well known, when a building is constructed on soft ground, the loads of the foundation 1 and building 2 are applied to the ground, causing consolidation settlement of the ground. At the same time, the ground, as an elastic body, undergoes shear deformation, and settlement due to shear deformation also occurs. Settlement due to shear deformation causes destruction as if a fault had occurred and the upper layer had slipped. In Figure 10, the failure lines (slip lines) 71 and 72 caused by this shear deformation are shown by dashed dotted lines. When uneven settlement occurs, causing the right side to settle, failure line 71 occurs, extending downward from right to left, and when uneven settlement occurs, causing the left side to settle, failure line 72 occurs, extending downward from left to right.

[0047] The reinforcing layer 6 in the second embodiment has the purpose of forming a hard layer (inelastic layer) in the necessary shape at the necessary location in the ground, thereby suppressing the shear deformation. In other words, in Figure 10, the reinforcing layer 6 on the left side absorbs and suppresses the elastic deformation (shear deformation) of the ground when the foundation or building settles and tilts on the right side, while the reinforcing layer 6 on the right side absorbs and suppresses the elastic deformation of the ground when the foundation or building settles and tilts on the left side. This prevents uneven settlement of the foundation or building. In other words, the building and foundation construction method of the embodiment focuses on the causes of uneven settlement and achieves low-cost settlement prevention by injecting chemicals according to the position and shape of the foundation. Such uneven settlement due to shear deformation can occur not only during construction (instantaneous settlement), but also due to the effects of vibrations and liquefaction during a major earthquake. The building and foundation construction method of the embodiment have the function of effectively preventing such uneven settlement due to shear deformation.

[0048] The depth region of the reinforcement layer 6 may be designed to penetrate the failure line caused by shear deformation, and a structure that blocks landslides may be adopted. The failure lines 71 and 72 caused by shear deformation can be predicted by calculation based on the bearing capacity of the ground and the overall load of the foundation 1 and building 2, and software for this purpose is commercially available (https: / / www.forum8.co.jp / topic / up61-p17.htm). Therefore, it is possible to predict the failure line from the load of the planned foundation 1 and building 2 and the actually measured bearing capacity of the ground, and then set the depth region of the reinforcement layer 6 so that it intersects with this line.

[0049] The function of the reinforcing layer 6 is particularly significant when constructing a relatively heavy building, such as a mid-rise building, on a site with poor ground strength. Conventionally, measures to prevent subsidence, including uneven subsidence, have often relied on pile methods such as anchor piles and friction piles. However, while a structure in which piles are directly connected to hard ground such as diluvial deposits is suitable for preventing subsidence, as taught in Patent Document 1, there have been many cases in which, during a major earthquake, the piles directly transmit vibrations to the building 2, causing the building 2 to shake violently, resulting in the fracture of the pile heads and the collapse of the building 2. For this reason, there is an increasing need for ground reinforcement that does not rely on piles. The reinforcing layer 6 in the second embodiment is suitable for meeting this requirement at low cost.

[0050] In the second embodiment, the reinforcing layer 6 is provided together with the water stop layer 3, but the above-described function of the reinforcing layer 6 is exerted even when the water stop layer 3 is not provided. That is, even when only the reinforcing layer 6 is provided without the water stop layer 3, the effect of preventing uneven settlement due to shear deformation of the ground can be obtained. Furthermore, the reinforcing effect of the reinforcing layer 6 can be obtained even when the upper end of the reinforcing layer 6 is not in contact with the foundation 1, so the upper end of the reinforcing layer 6 may be separated from the foundation 1. In the second embodiment, the reinforcing layer 6 can also be formed after the construction of the root cutting and the earth retaining wall 5. That is, after first injecting the water-stopping material to form the water-stopping layer 3, the root cutting and the earth retaining wall 5 can be formed, and then an injection pipe can be inserted from the surface of the bottom after the root cutting to inject the reinforcing material, thereby forming the reinforcing layer 6. After the reinforcing layer 6 is formed, the foundation 1 is constructed.

[0051] In the first and second embodiments described above, the earth retaining wall 5 is left in place without being removed. When removing them, the support materials 51 and sheet piles 52 are backfilled if they were present. In some cases, to ensure the above effects, a water-stopping material is injected into the backfilled area to provide an additional water-stopping layer, further enhancing the effect. However, the construction method of the embodiment in which the earth retaining structure 5 is left in place without being removed has several advantages. One is the shortening of the construction period. The construction period is shortened by the amount required to remove the earth retaining structure 5, resulting in lower labor costs. From another perspective, when building on narrow land, such as in urban areas, it can be difficult to remove the earth retaining structure. When constructing the earth retaining structure 5, it can be done from the inside (from the space where the roots have been excavated), but when removing it, it must be done from the outside because the foundation 1 is located on the inside. In this case, when construction is done on narrow land, heavy machinery often cannot be used because the boundary with the neighboring property is close, and removal can be very expensive. If the earth retaining structure is left in place, this problem does not occur.

[0052] Furthermore, in relation to the structure of each embodiment, a positive significance is that the water-stopping effect on the side of the foundation 1 can be ensured in a simple manner. As described above, when the earth retaining wall 5 is removed in the structure of each embodiment, a gap is created on the side of the outer periphery of the foundation 1, and this space must be backfilled. Because the water-stopping layer 3 is not formed in this area, even if backfilling and compaction are performed, it may still become a path for underground water to rise. To be on the safe side, it is possible to inject water-stopping material again after backfilling to form an additional water-stopping layer, but this would increase costs and construction time. In the structure of each of the above embodiments in which the earth retaining wall 5 remains, such problems do not occur, and water-stopping on the side of the foundation 1 can be achieved in a simple manner.

[0053] Next, an embodiment of the liquefaction prevention method of the present invention will be described with reference to Fig. 11. Fig. 11 is a schematic front cross-sectional view showing the liquefaction prevention method of the embodiment. Like the above-described embodiments, the liquefaction prevention method of the embodiment also focuses on restricting the movement of underground water. Specifically, the liquefaction prevention method of the embodiment is a method of forming a water stop layer 8 along the contour of the horizontal area where the building is located by injecting a water stop material into the ground at a predetermined depth, thereby suppressing the outflow of water from the ground directly below the building. Therefore, the description of the formation of the water stop layer in the above-described embodiments can also be a description of the liquefaction prevention method of the embodiment.

[0054] However, the liquefaction prevention method of the embodiment can also be applied to existing buildings. That is, a configuration in which the water stop layer 3 is formed beforehand when the building is constructed to prevent liquefaction can be adopted, but a configuration in which the water stop layer 8 is formed after the building is constructed to prevent liquefaction can also be adopted. Figure 11 shows the liquefaction prevention method of this example. As shown in Fig. 11, in this method, a water-stopping material is injected into the ground of an existing building to form a water-stopping layer 8. In this case, the water-stopping layer 8 is formed so as to extend downward below the outer periphery of the foundation 1. It is preferable that the upper end of the water-stopping layer 8 be in contact with the bottom part of the foundation 1. Therefore, as shown in Fig. 11, the water-stopping material may be injected with an injection pipe 80 at an angle.

[0055] FIG. 12 is a schematic front cross-sectional view showing the effect of the liquefaction prevention method of the embodiment. As is well known, liquefaction, which can cause serious damage, occurs during a major earthquake in non-clay soils, such as sandy soils, where groundwater pools (groundwater pools) WP are located relatively shallow underground. The groundwater pools WP fill the gaps between soil particles, but the vibrations of a major earthquake cause them to rise as groundwater flows (WF), reaching the ground surface and generating sand boils. Sand boils that reach the ground surface can lift light structures like manhole covers, and even if they do not reach the ground surface, they can cause damage such as road upheaval. Furthermore, when the underground water that constitutes the groundwater pools WP escapes, the gaps between soil particles become smaller and the soil particles become denser, reducing the bearing capacity of the soil and causing subsidence in areas where the building load is heavy. This can result in damage such as tilting of the foundation 10 and building 20, as shown on the left side of Figure 12.

[0056] On the other hand, in a building that has implemented the liquefaction prevention method of the embodiment, when a major earthquake occurs, the water in the groundwater reservoir WP will attempt to rise as a groundwater flow WF due to vibrations, but the foundation 1 acts as a wall directly above, and the water-stopping layer 8 acts as a wall to the side. As a result, the groundwater flow WF directly below the foundation 1 does not reach the ground surface, but instead bounces off the underside of the foundation 1 and returns to the groundwater reservoir WP. As a result, no significant subsidence occurs in the ground, and no uneven settlement occurs that would cause the foundation 1 or building 2 to tilt. Large subsidence occurs because water reaches the ground surface as sand boils and escapes; if water pressure is held back within the ground and the water remains, the water will not escape and no significant subsidence occurs. Therefore, no liquefaction damage occurs.

[0057] To achieve this effect, it is preferable that the upper end of the water-stopping layer 8 is in contact with the foundation 1. If they are not in contact, it is preferable that the distance between them is small, and is 50 cm or less, more preferably 30 cm or less, and even more preferably 10 cm or less. It is also preferable that the bulb portions 81 of the water-stopping material that make up the water-stopping layer 8 are in contact with each other in the horizontal direction. If the bulb portions 81 are not in contact with each other in the horizontal direction, it is preferable that the distance between them is 50 cm or less, more preferably 30 cm or less, and even more preferably 10 cm or less.

[0058] If civil engineering techniques were applied directly to prevent liquefaction by forming a water-stop layer in a building, a water-stop layer would be formed transversely in the ground throughout the entire building site. However, this construction method requires a huge amount of water-stop material, making it an expensive method that accounts for a significant portion of the building's construction costs. On the other hand, in the method of the embodiment, the water-stop layer 8 is formed to restrict the lateral movement of underground water in the necessary area relative to the area occupied by the building (horizontal area). This requires significantly less water-stop material, making liquefaction prevention extremely inexpensive. Furthermore, this construction method can be applied to existing buildings and is extremely versatile. Such a water blocking layer 8 can also function as a reinforcing layer in the second embodiment. Therefore, the liquefaction prevention method of the embodiment can also be a method for reinforcing the ground as well as preventing liquefaction.

[0059] Next, an embodiment of the invention of the method for preventing building collapse will be described. Fig. 13 is a schematic front view showing the embodiment of the invention of the method for preventing building collapse. The configurations of the above-described embodiments are applications of the formation of a water-stopping layer by chemical injection, which is used in civil engineering, to the field of architecture. They are characterized by forming a water-stopping layer 3 along the periphery of the foundation 1. In this case, particularly by providing the water-stopping layer 3 on the outside of the foundation 1, it is possible to prevent the inflow of groundwater from neighboring land, stabilizing the neighboring land, and suppressing the rise of groundwater below the foundation 1, thereby preventing the foundation 1 from subsiding. Furthermore, particularly by providing the water-stopping layer 3 below the lowest part of the foundation 1, it is more effective in suppressing the intrusion and rise of groundwater from directly below the foundation 1. The concept of providing a water-stopping layer 3 in relation to the shape and position of the foundation 1 of a building can also be applied from the perspective of preventing river disasters. This is the concept behind the embodiments of the invention of a method for preventing building collapse. That is, the method for preventing building collapse of the embodiment forms a water-stopping layer 3 along the periphery of the river-side foundation of a building to prevent collapse.

[0060] As shown in Figure 13, assume that a building 94, such as a detached house, is built near a river 93. In this case, as shown by the dashed line in Figure 13, assume that the bank collapses due to cracks caused by heavy rain or a major earthquake, and the ground gradually erodes. In this case, the water-stopping layer 3 serves to stop ground erosion caused by the amplification of the river 93. In other words, without the water-stopping layer 3, the amplified flow of the river 93 would inevitably seep under the foundation 1 and carry away the soil of the ground. However, the presence of the water-stopping layer 3 prevents the flow of the river 93 from seeping under the foundation 1. This prevents the outflow of soil and sand from under the foundation 1, preventing the collapse of the building 94. Such a water stopping layer 3 is formed to extend horizontally along the edge of the foundation 1 on the side facing the river 93, and is formed to occupy a sufficient area vertically. If there is space on the site, it is preferable to increase the width in the direction connecting the foundation 1 and the river 93, or to form multiple rows. [Explanation of symbols]

[0061] 1 Basics 2. Building 3 Water-stopping layer 31 Bulb 41 Injection tube 42 injection points 5 Bracing 51 Support material 52 Yaita 6 Reinforcement layer 61 Bulb 8 Water-stopping layer

Claims

1. A building consisting of a foundation and a building constructed on the foundation, A water-stopping layer is provided by injecting water-stopping material into the ground. The waterproofing material is made of water glass and hardening material, and is not mixed with soil. A building characterized in that the water-stopping layer is provided along the outer periphery of the foundation and extends vertically to form a water-stopping wall.

2. 2. The building according to claim 1, wherein the water blocking layer is provided on the outside of the foundation and surrounds the foundation in a plan view.

3. A building as described in claim 1, characterized in that the water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes the area above the lowest depth position of the foundation.

4. A building consisting of a foundation and a building constructed on the foundation, A water-stopping layer is provided by injecting water-stopping material into the ground. The water blocking layer is provided along the outer periphery of the foundation and extends vertically to form a water blocking wall, A building characterized in that formwork used during the construction of the foundation remains between the water-stopping layer and the side of the outer periphery of the foundation, filling the space between the water-stopping layer and the side of the outer periphery of the foundation.

5. A building as described in claim 1, characterized in that the water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes the area below the lowest depth position of the foundation.

6. 2. The building according to claim 1, wherein the water-stopping layer is formed so as to extend downward below the outer periphery of the foundation.

7. A building consisting of a foundation and a building constructed on the foundation, A water-stopping layer is provided by injecting water-stopping material into the ground. The water blocking layer is provided along the outer periphery of the foundation and extends vertically to form a water blocking wall, A building characterized in that the water-stopping layer is formed so as to extend downward from the bottom surface of the outer periphery of the foundation.

8. The water blocking layer is provided on the outside of the foundation, A building as described in claim 1, characterized in that a reinforcing layer is provided on the underside of the outer periphery of the foundation, the reinforcing layer being reinforced by injecting reinforcing material into the ground, and the reinforcing layer extends along the outer periphery of the foundation.

9. A foundation construction method for a building, comprising: a water stop layer forming step of injecting a water stop material into the ground in advance to form a water stop layer; After the water-stopping layer formation process, there is a root-cutting process in which the site is excavated and the roots are cut for the foundation construction. a retaining step of providing a retaining wall made of a material separate from the water stopping layer on the wall surface of the space formed by the root cutting; The foundation construction process follows the earth retaining process. It has A foundation construction method characterized in that the water-stopping material injection process is a process of forming a water-stopping wall by injecting water-stopping material into a predetermined depth area so as to surround the horizontal area where root excavation is planned in a plan view.

10. The foundation construction method according to claim 9, characterized in that the predetermined depth region includes a region between the position of the lowest depth of the root excavation in the root excavation process and a shallower position from that position.

11. The foundation construction method according to claim 9, characterized in that the predetermined depth region includes a region between the position of the lowest depth of the root excavation in the root excavation process and a deeper position from that position.

12. A method for preventing liquefaction at a building site, comprising: This method involves injecting a water-stopping material into the ground at a predetermined depth to form a water-stopping layer that extends downward from the bottom surface of the outer periphery of the foundation along the periphery of the foundation of the building, forming a water-stopping wall and suppressing the outflow of water from the ground directly below the building. A method for preventing liquefaction on a building site, characterized in that the water-stopping material is made of water glass and a hardening material and is not mixed with soil.

13. A method for preventing collapse of a building constructed on a site near a river due to river erosion, comprising: This method involves injecting a water-stop material into the ground at a predetermined depth, forming a water-stop layer that extends downward from the lowest depth position of the outer periphery of the foundation along the periphery of the building foundation, thereby forming a water-stop wall, and preventing the ground below the foundation from eroding due to the action of the water-stop wall. This method for preventing collapse of a building is characterized in that the water-stopping material is made of water glass and a hardening material and is not mixed with soil, thereby preventing collapse of the building.

14. A building consisting of a foundation and a building constructed on the foundation, A water-stopping layer is provided by injecting water-stopping material into the ground. The water blocking layer is provided along the outer periphery of the foundation and extends vertically to form a water blocking wall, A building characterized in that the upper end of the water-stopping layer is underground and no load-transmitting member is provided between the upper end of the water-stopping layer and the outer periphery of the building.

15. The building according to claim 14, characterized in that the water-stopping layer is provided on the outside of the foundation and surrounds the foundation in a plan view.

16. A building as described in Claim 14, characterized in that the water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes the area above the lowest depth position of the foundation.

17. A building as described in Claim 14, characterized in that the water-stopping layer is provided on the outside of the foundation, and the vertical area in which the water-stopping layer is formed includes an area below the position of the lowest depth of the foundation.

18. A building as described in Claim 14, characterized in that the water-stopping layer is formed so as to extend downward below the outer periphery of the foundation.

19. The water-stopping layer is provided on the outside of the foundation, A building as described in claim 14, characterized in that a reinforcing layer is provided on the underside of the outer periphery of the foundation, the reinforcing layer being reinforced by injecting reinforcing material into the ground, and the reinforcing layer extends along the outer periphery of the foundation.

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