Method for reinforcing and raising a building on an expansive soil foundation

Abstract

The application relates to a building reinforcement and lifting method on an expansive soil foundation, which comprises the following steps: forming a curtain wall, drilling holes downwards around the building foundation bottom plate to reach the non-expansive soil layer, forming multiple interval curtain holes, grouting into the curtain holes, the grouting ranges of two adjacent curtain holes being mutually overlapped to form a closed curtain wall; forming a shallow layer reinforcement, drilling reinforcement grouting holes downwards on the raft top, grouting and reinforcing the shallow layer expansive soil foundation to form a shallow layer reinforcement; forming horizontal lap reinforcement, arranging multiple horizontal lap reinforcements extending along the horizontal direction between the curtain walls on the opposite sides in the expansive soil layer; forming vertical pile foundation reinforcement, arraying multiple vertical pile foundation reinforcements extending along the vertical direction, and the vertical pile foundation reinforcements respectively connecting with the corresponding horizontal lap reinforcements on the path; and lifting grouting, arranging lifting holes in the curtain wall, performing pressure grouting from bottom to top to the bottom of the lifting holes to realize building lifting.

Description

Technical Field

[0001] This invention relates to the field of building reinforcement and lifting technology, and more particularly to a method for reinforcing and lifting buildings on expansive soil foundations. Background Technology

[0002] Expansive soil is widely distributed in my country. Under natural conditions, it is generally hard or stiff plastic, but its bearing capacity decreases when exposed to water, making it extremely unstable. Expansive soil expands when it absorbs water, causing buildings to bulge; it shrinks when it loses water, causing soil cracking and building subsidence. This repeated expansion and contraction deformation poses a significant threat to building foundations. The damage is even greater when the expansive soil layer is thick and a low-rise building is on top. Methods for reinforcing and raising the foundations of existing buildings on expansive soil include replacement, waterproofing, and soil improvement. Replacement is only suitable for shallow expansive soil layers. When the expansive soil layer is thick and the atmospheric influence is deep, replacement is uneconomical and cannot effectively address the hazards of expansive soil. Waterproofing only blocks some water infiltration into the foundation; when rainfall is heavy or the groundwater level rises, the expansive soil will still expand and contract. Soil improvement involves injecting a grout composed of chemical modifiers and cementitious materials to improve soil expansibility and achieve reinforcement. However, this method is not thorough, and secondary settlement may occur. Summary of the Invention

[0003] The purpose of this invention is to solve at least one technical problem in the background art and to provide a method for reinforcing and lifting buildings on expansive soil foundations.

[0004] To achieve the above objectives, the present invention provides a method for reinforcing and lifting buildings on expansive soil foundations, comprising:

[0005] To form a curtain wall, vertical holes are drilled around the foundation slab of the building, down to the non-expansive soil layer, forming multiple spaced curtain holes. Grout is injected into the curtain holes, and the grouting ranges of two adjacent curtain holes interlock and overlap to form a closed curtain wall.

[0006] To form a shallow reinforced body, holes are drilled downwards from the top of the raft slab to form reinforcement grouting holes, and the shallow expansive soil foundation is reinforced by grouting to form a shallow reinforced body.

[0007] To form horizontally overlapping reinforcements, multiple horizontally overlapping reinforcements extending in the horizontal direction are arranged between the curtain walls on opposite sides in the expansive soil layer.

[0008] A vertical pile foundation reinforcement is formed, and multiple vertical pile foundation reinforcements extending in the vertical direction are arranged in an array in the curtain wall. Each of the vertical pile foundation reinforcements intersects with the corresponding horizontal overlapping reinforcement on the path.

[0009] Lifting grouting, arranging lifting holes in curtain wall, and performing bottom-up pressure grouting to the bottom of the lifting hole to realize building lifting.

[0010] According to one aspect of the present application, the drill-grouting integrated machine is used to sequentially perform grouting to the curtain holes in multiple segments in the vertical direction, and the grout is sprayed from the nozzle of the grouting pipe and pressed into the surrounding soil and solidified within 30-60s to form the curtain wall.

[0011] The grouting pressure in the curtain hole is 0.3-0.5Mpa, and the thickness of the curtain wall is 3m.

[0012] According to one aspect of the present application, the drill-grouting integrated machine is used to perform grouting to the reinforcement grouting hole in multiple segments in the vertical direction by using the forward grouting method, the grout is sprayed from the nozzle of the grouting pipe and solidified within 30-60s, and the depth of each forward movement is 30-50cm.

[0013] According to one aspect of the present application, the drill-grouting integrated machine is used to perform pressure grouting to the bottom of the lifting hole and segmented backward grouting to lift the building.

[0014] According to one aspect of the present application, the horizontal overlap reinforcement bodies are arranged on the curtain walls on both sides in an interval staggered along the vertical direction, and the free ends of the horizontal overlap reinforcement bodies are overlapped when projected along the vertical direction.

[0015] According to one aspect of the present application, the vertical pile foundation reinforcement bodies respectively pass through the corresponding horizontal overlap reinforcement bodies and are connected with the horizontal overlap reinforcement bodies at the intersection, and the end portions extend into the non-swelling soil layer.

[0016] According to one aspect of the present application, pressure grouting is performed to the bottom of the lifting hole, the grouting pipe stops grouting when passing through the range of the horizontal overlap reinforcement body, and the grouting continues after the grouting pipe leaves the range of the horizontal overlap reinforcement body.

[0017] According to one aspect of the present application, during the process of performing pressure grouting to the lifting hole, the grouting pressure is greater than the reference pressure and less than 1.8 times the reference pressure, wherein the reference pressure = the gravity of the building / the area of the raft.

[0018] According to one scheme of the present application, the curtain wall arrangement isolates the foundation soil below the raft from the foundation soil outside the raft, provides a closed environment for the reinforcement grouting and lifting grouting, avoids the interference from the peripheral environment, prevents the loss of the grouting liquid, and saves the grouting material; the shallow reinforcement plays a buffering role when transmitting the upward lifting force, protects the bottom plate, and reduces the damage to the building; the horizontal overlap reinforcement and the vertical pile reinforcement cross each other to form a grid-like skeleton structure, which restricts the expansion and shrinkage deformation of the soil, forms a stable foundation, simultaneously improves the bearing capacity of the soil in the horizontal and vertical directions, prevents the lateral and vertical deformation of the foundation soil, and thus reduces the uneven settlement of the foundation; the pressure grouting is performed at the bottom of the lifting hole, the soil layer in the curtain wall is continuously filled and compacted as the grouting liquid in the curtain wall continuously increases, the lifting force is formed as the soil pressure increases and the density increases, the horizontal reinforcement and the vertical reinforcement are lifted together, and the building is gradually lifted to the set lifting height. In the present application, the shallow reinforcement is formed to improve the characteristics of the swelling soil, such as swelling when encountering water and shrinking when losing water, to improve the density and stiffness of the foundation soil layer, and to play a buffering role during the lifting operation, so that the lifting stress is more uniform. Further, during the lifting grouting, the soil layer in the curtain wall is continuously filled and compacted as the grouting liquid in the curtain wall continuously increases, the lifting force is formed as the soil pressure increases and the density increases, the horizontal overlap reinforcement and the vertical pile reinforcement are lifted together, and the building is gradually lifted to the set lifting height.

[0019] According to one scheme of the present application, the drilling and grouting integrated machine performs the grouting to the curtain holes in multiple segments in the vertical direction, the grouting liquid is sprayed from the nozzle of the grouting pipe and pressed into the surrounding soil, and solidified within 30-60s to form the curtain wall; such arrangement can make the construction efficient, the grouting liquid solidifies quickly, reduces the softening influence on the soil, and prevents the secondary settlement of the building.

[0020] According to one scheme of the present application, the drilling and grouting integrated machine performs the pressure grouting to the bottom of the lifting hole, and performs the lifting of the building by the segmented and backward grouting. Such arrangement can prevent the splitting of the grouting liquid to the foundation and the formation of the grouting leakage channel when the same point is continuously grouted or the grouting pressure is increased. The multiple times of backward grouting make the grouting liquid more uniformly apply the extrusion force to the surrounding soil, and the lifting is more uniform.

[0021] According to one scheme of the present application, the horizontal lapping reinforcements are arranged on the curtain walls on both sides in staggered intervals along the vertical direction, and the projections of the free ends of the horizontal lapping reinforcements overlap when projected along the vertical direction. In this way, the rising of the underground water is hindered layer by layer, the seepage path is increased, the hydraulic gradient is reduced, the underground water level inside the curtain wall is much lower than the underground water level outside, and the influence of the water on the soil body is smaller and smaller as the height increases; meanwhile, the upper and lower horizontal lapping reinforcements constrain the swelling deformation of the soil body, the soil pressure on each horizontal lapping reinforcement can offset a part of the soil pressure on the other horizontal lapping reinforcement, and a certain degree of balance is achieved, so that the force transmitted to the shallow layer reinforcement is smaller, the force transmitted to the foundation is smaller, and thus the deformation of the foundation is well controlled; finally, the horizontal lapping reinforcements can effectively constrain the lateral deformation of the foundation soil, thereby improving the vertical bearing capacity of the foundation soil.

[0022] According to one scheme of the present application, the vertical pile foundation reinforcements respectively pass through the corresponding horizontal lapping reinforcements and are connected with the horizontal lapping reinforcements at the intersections, and the end portions extend into the non-swelling soil layer. The vertical pile foundation reinforcements are arranged in a plum blossom shape, forming a structure similar to a pile foundation. In this way, the vertical pile foundation reinforcements compact and replace part of the swelling soil, enhance the internal friction angle of the composite soil body, and improve the vertical bearing capacity and deformation resistance of the foundation soil; meanwhile, the shear resistance of the soil body is increased, and the collapse deformation of the foundation can be prevented when the swelling soil shrinks due to water loss. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A flow chart schematically showing a method for reinforcing and lifting a building on an expansive soil foundation according to an embodiment of the present application;

[0024] Figure 2 A structural diagram schematically showing a building reinforcing and lifting structure according to Embodiment 1 of the present application;

[0025] Figure 3 A grouting diagram schematically showing a shallow layer reinforcement, a horizontal lapping reinforcement and a vertical pile foundation reinforcement according to Embodiment 1 of the present application;

[0026] Figure 4 A structural diagram schematically showing a horizontal lapping reinforcement according to Embodiment 1 of the present application;

[0027] Figure 5 A grouting hole position plan view schematically showing a vertical pile foundation reinforcement according to Embodiment 1 of the present application;

[0028] Figure 6 A diagram schematically showing an underground water level after the arrangement of a curtain wall and a horizontal lapping reinforcement according to Embodiment 1 of the present application;

[0029] Figure 7Fig. 1 is a schematic diagram showing the stress of the horizontal overlapping reinforcement body when the soil body is expanded according to embodiment 1 of the present application;

[0030] Figure 8 Fig. 4 is a schematic diagram showing the lifting hole lifting grouting range according to embodiment 1 of the present application. DETAILED DESCRIPTION

[0031] The present application will now be discussed with reference to exemplary embodiments. It should be understood that the discussed embodiments are merely for the purposes of better illustrating and thus enabling those of ordinary skill in the art to make and use the present application, and are not intended to impose any limitations on the scope of the present application.

[0032] As used herein, the term "comprising" and variations thereof are to be construed as open-ended terms meaning "including, but not limited to". The term "based on" is to be construed as "based at least in part on". The terms "one embodiment" and "an embodiment" are to be construed as "at least one embodiment".

[0033] Figure 1 Fig. 1 is a schematic diagram showing the stress of the horizontal overlapping reinforcement body when the soil body is expanded according to embodiment 1 of the present application; Figure 1 As shown in the figure, in the present embodiment, the building reinforcement lifting method on the expansive soil foundation comprises:

[0034] a. forming a curtain wall, drilling holes vertically downwards around the building foundation slab to the non-expansive soil layer to form a plurality of spaced curtain holes, grouting into the curtain holes, the grouting range of adjacent two curtain holes overlapping each other to form a closed curtain wall;

[0035] b. forming a shallow layer reinforcement, drilling holes downwards on the top of the raft to form reinforcement grouting holes, grouting and reinforcing the shallow layer of the expansive soil foundation to form a shallow layer reinforcement;

[0036] c. forming a horizontal overlapping reinforcement body, arranging a plurality of horizontal overlapping reinforcement bodies extending along the horizontal direction between the curtain walls on opposite sides in the expansive soil layer;

[0037] d. forming a vertical pile foundation reinforcement body, arranging a plurality of vertical pile foundation reinforcement bodies extending along the vertical direction in the curtain wall in an array, each vertical pile foundation reinforcement body respectively interfacing with the corresponding horizontal overlapping reinforcement body on the path;

[0038] e. lifting grouting, arranging a lifting hole in the curtain wall, performing pressure grouting from bottom to top to the bottom of the lifting hole to realize building lifting.

[0039] In the present application, the arrangement of the curtain wall isolates the foundation soil below the raft from the foundation soil outside the raft, provides a closed environment for the reinforcement grouting and lifting grouting, avoids the interference from the peripheral environment, prevents the loss of grouting liquid, and saves the grouting material; the shallow reinforcement body plays a buffering role when transmitting the upward lifting force, protects the bottom plate, and reduces the damage to the building; the horizontal overlap reinforcement body and the vertical pile reinforcement body are connected to each other in a horizontal and vertical staggered manner to form a grid-like skeleton structure, the skeleton structure constrains the expansion and shrinkage deformation of the soil body, forms a stable foundation, simultaneously improves the bearing capacity of the soil body in the horizontal and vertical directions, prevents the lateral and vertical deformation of the foundation soil body, and thus can reduce the uneven settlement of the foundation base; the pressure grouting is performed at the bottom of the lifting hole, the soil layer in the curtain wall is continuously filled and compacted as the grouting liquid in the curtain wall continuously increases, the lifting force is formed as the pressure of the soil body increases and the compactness increases, the horizontal reinforcement body and the vertical reinforcement body are lifted together, and the building is gradually lifted to the set lifting height.

[0040] According to the above scheme of the present application, the shallow reinforcement body is formed to improve the characteristics of the swelling soil that swells when water is added and shrinks when water is lost, improve the compactness and rigidity of the foundation soil layer, and play a buffering role during lifting operation, so that the lifting stress is more uniform. Further, during the lifting grouting process, the soil layer in the curtain wall is continuously filled and compacted as the grouting liquid in the curtain wall continuously increases, a lifting force is formed as the pressure of the soil body increases and the compactness increases, the horizontal overlap reinforcement body and the vertical pile reinforcement body are lifted together, and the building is gradually lifted to the set lifting height.

[0041] Further, in the present embodiment, the drilling and grouting integrated machine is used to sequentially grout the curtain hole in multiple segments in the vertical direction, the grouting liquid is sprayed from the nozzle of the grouting pipe and then pressed into the surrounding soil body and solidified within 30-60s to form the curtain wall; in this way, the construction is efficient, the grouting liquid solidifies quickly, the softening effect on the soil body is reduced, and secondary settlement of the building is prevented.

[0042] In the present embodiment, the grouting pressure in the curtain hole is 0.3-0.5Mpa, and the thickness of the curtain wall is 3m.

[0043] Further, in the present embodiment, the drilling and grouting integrated machine is used to grout the reinforcement grouting hole in multiple segments in the vertical direction by using the forward grouting method, the grouting liquid is sprayed from the nozzle of the grouting pipe and then solidified within 30-60s, and the depth of each forward movement is 30-50cm.

[0044] Further, in the embodiment, the drilling and grouting integrated machine is used to perform pressure grouting to the bottom of the lifting hole, and the building is lifted by segmental and backward grouting. In this way, the splitting of the slurry to the foundation caused by continuous grouting or increased grouting pressure at the same point can be prevented, and the slurry leakage channel is formed. The multiple backward grouting makes the slurry more uniformly applied to the surrounding soil, and the lifting is more uniform.

[0045] Further, in the embodiment, the horizontal overlapping reinforcement bodies are arranged on the curtain walls on the two sides in the vertical direction with intervals and staggered, and the free ends of the horizontal overlapping reinforcement bodies are overlapped when projected in the vertical direction. In this way, the groundwater is blocked layer by layer during the rising of the groundwater, the seepage path is increased, the hydraulic gradient is reduced, the groundwater level inside the curtain wall is far lower than the groundwater level outside, and the influence of the water on the soil body is smaller and smaller as the height increases. Meanwhile, the upper and lower horizontal overlapping reinforcement bodies can constrain the swelling deformation of the soil body, the soil pressure on each horizontal overlapping reinforcement body can offset a part of the soil pressure, and a certain degree of balance is achieved. Thus, the force transmitted to the shallow layer reinforcement body is smaller, and the force transmitted to the foundation is smaller, so that the deformation of the foundation is well controlled. Finally, the horizontal overlapping reinforcement body can effectively constrain the lateral deformation of the foundation soil, so as to improve the vertical bearing capacity of the foundation soil.

[0046] Further, in the embodiment, the vertical pile foundation reinforcement bodies respectively pass through the corresponding horizontal overlapping reinforcement bodies and are connected with the horizontal overlapping reinforcement bodies at the intersection, and the end portions extend into the non-swelling soil layer. In the embodiment, the vertical pile foundation reinforcement bodies are arranged in a plum blossom shape, and a structure similar to a pile foundation is formed. In this way, the vertical pile foundation reinforcement bodies can compact and replace part of the swelling soil, enhance the internal friction angle of the composite soil body, and improve the vertical bearing capacity and anti-deformation capacity of the foundation soil. Meanwhile, the shear resistance of the soil body is increased, and the collapse deformation of the foundation can be prevented when the swelling soil shrinks due to water loss.

[0047] Further, in the embodiment, pressure grouting is performed to the bottom of the lifting hole, the grouting pipe is stopped when passing through the range of the horizontal overlapping reinforcement body, and the grouting is continued after the grouting pipe leaves the range of the horizontal overlapping reinforcement body.

[0048] Further, in the embodiment, during the pressure grouting to the lifting hole, the grouting pressure is greater than the reference pressure and less than 1.8 times the reference pressure, wherein the reference pressure = the gravity of the building / the area of the raft.

[0049] Based on the above scheme of the application, the scheme of the application will be described in detail in the manner of a specific embodiment in combination with the drawings.

[0050] Embodiment 1

[0051] A substation building, consisting of one floor above ground and one floor below ground, utilizes a raft foundation. The building is relatively low in height, with a small superstructure load and a shallow foundation depth, situated on expansive soil. During the rainy season, heavy rainfall raises the groundwater level, causing deformation of the expansive soil foundation and resulting in uneven settlement. Based on the identified problems, this embodiment proposes a method for reinforcing and lifting buildings on expansive soil foundations, including the following construction steps:

[0052] Step 1: Form the curtain wall 21, as follows Figure 2 As shown, vertical holes are drilled downwards around the foundation slab of building 01, reaching the non-expansive soil layer to form multiple spaced curtain holes 1. Grout is injected into the curtain holes, with the grouting areas of adjacent curtain holes interlocking and overlapping to form a closed curtain wall 21 with an effective thickness of 3m. The grouting pressure in the curtain holes 1 is determined according to the design thickness of the curtain wall and the soil layer, and is generally 0.3-0.5MPa.

[0053] Step 2: Form a shallow solidification layer 22, such as Figure 2 , Figure 3 As shown, a grouting hole 2 is drilled downwards from the top of the raft foundation 02 to reinforce the shallow expansive soil foundation, forming a shallow reinforced body 22. The purpose is to improve the expansive soil's properties of swelling upon contact with water and shrinking upon loss of water, increasing the density and stiffness of the foundation soil layer. This serves as a buffer zone during lifting operations, resulting in more even stress distribution during lifting. Grouting is performed using a drilling and grouting integrated machine, employing a forward-moving grouting method. Grouting is carried out in multiple vertical sections. The grout solidifies within 30-60 seconds after being ejected from the grouting pipe nozzle, with each advance reaching a depth of 30-50 cm. It should be noted that... Figure 3 The thick solid line represents the grouting reinforcement range of grouting hole 2, and the thin dashed line represents the range where grouting of grouting hole 2 stops.

[0054] Step 3: Form horizontal lap reinforcement 23, such as Figure 3 , Figure 4 As shown, the reinforcing grouting hole 2 continues drilling downwards, grouting and reinforcing within the area where the horizontal reinforcement is arranged; grouting stops in the remaining areas, forming a horizontal overlapping reinforcement 23. The horizontal overlapping reinforcement 23 divides the expansive soil foundation into layers, such as... Figure 6 As shown, the rising groundwater is obstructed at each level, increasing the seepage path and reducing the hydraulic gradient. This results in the groundwater level inside the curtain wall being much lower than the external groundwater level, with the soil being less affected by water as you go higher up. Figure 7As shown, the upper and lower horizontal reinforcing bodies constrain the swelling deformation of the soil body, and the earth pressure on each horizontal reinforcing body can offset a part of each other to a certain extent, achieving a certain degree of balance. Thus, the force transmitted to the shallow reinforcing body is smaller, and the force transmitted to the foundation is smaller. Therefore, the deformation of the foundation is well controlled. Finally, the horizontal reinforcing body can effectively constrain the lateral deformation of the foundation soil, thereby improving the vertical bearing capacity of the foundation soil. Grouting is performed using a drilling and grouting integrated machine, and the grouting is performed in multiple segments in the vertical direction. The slurry is sprayed from the grouting pipe nozzle and solidifies within 30-60 seconds. The depth of each advance can be 30-50 cm.

[0055] Step 4, forming a vertical pile foundation reinforcing body 24, as shown in Figure 3 As shown, part of the reinforcing grouting hole 2 continues to drill down to the non-swelling soil layer and grout within the range of the vertical reinforcing body to form a vertical pile foundation reinforcing body 24. As shown in Figure 5 The vertical pile foundation reinforcing body 24 is arranged in a quincunx shape to form a structure similar to a pile foundation. The vertical pile foundation reinforcing body 24 compacts and replaces part of the swelling soil, enhances the internal friction angle of the composite soil body, and improves the vertical bearing capacity and anti-deformation capacity of the foundation soil. At the same time, the shear resistance of the soil body is increased, which can prevent the collapse deformation of the foundation when the swelling soil shrinks due to water loss. Grouting is performed using a drilling and grouting integrated machine, and the grouting is performed in multiple segments in the vertical direction. The slurry is sprayed from the grouting pipe nozzle and solidifies within 30-60 seconds. The depth of each advance can be 30-50 cm.

[0056] Step 5, lifting grouting, as shown in Figure 8 As shown, part of the reinforcing grouting hole 2 drills down to the bottom of the swelling soil layer to form a lifting hole, and pressure grouting is performed at the bottom of the lifting hole. During lifting grouting, grouting is performed from bottom to top, and the grouting pipe will pass through the horizontal lapping reinforcing body 23. Grouting is stopped when passing through the range of the horizontal lapping reinforcing body 23, and then grouting is continued after leaving the range of the horizontal lapping reinforcing body 23. With the continuous increase of the slurry in the curtain wall, the soil layer in the curtain wall is continuously filled and compacted. With the increase of soil pressure and density, a lifting force is formed, which lifts the horizontal lapping reinforcing body and the vertical pile foundation reinforcing body together, and the building is gradually lifted to the set lifting height. After a certain period of time, the injection speed of the slurry gradually slows down under the same pressure. At this time, the grouting pipe is retreated by 10-30 cm, and pressure grouting is continued. After multiple retreats, the slurry is continuously injected to fill and compact the soil in the range, so that the building 01 is continuously lifted to the set lifting height. The grouting pressure setting principle during pressure grouting is: reference pressure = weight of the entire building 01 / area of the raft 02, the grouting pressure should be greater than the reference pressure and less than 1.8 times the reference pressure. It should be noted that Figure 8 The thick solid line represents the range of the lifting hole grouting lifting, and the thin dashed line represents the range of the lifting hole stopping grouting.

[0057] According to the above scheme of the present application, the curtain wall is arranged to form an enclosed space, preventing direct influence of surface precipitation on the foundation soil; the curtain wall exerts extrusion force on the soil in the range, making the uplift force more concentrated and effective, and the uplift speed more uniform and controllable; the curtain wall can prevent horizontal diffusion of the grouting material, saving the grouting material and improving construction efficiency.

[0058] The shallow reinforcement body aims to improve the characteristics of the swelling soil at the bottom of the foundation, such as swelling when meeting water and shrinking when losing water, and to improve the density and stiffness of the foundation soil layer, serving as a buffer zone during the lifting operation, so as to make the uplift stress more uniform.

[0059] The horizontal overlapping reinforcement body is arranged in an upper and lower layered overlapping manner, so that the groundwater is blocked layer by layer during the rising process, and the influence of water on the soil body becomes smaller and the swelling and deformation of the soil body become smaller as the water goes higher; at the same time, the upper and lower horizontal reinforcement bodies constrain the deformation of the swelling soil body and improve the bearing capacity of the foundation soil.

[0060] The vertical pile foundation reinforcement body is arranged in a plum blossom shape, forming a structure similar to a pile foundation. The vertical pile foundation reinforcement body compacts and replaces part of the swelling soil, enhances the internal friction angle of the composite soil body, and improves the vertical bearing capacity and anti-deformation capacity of the foundation soil; at the same time, the shear resistance of the soil body is improved, which can prevent the collapse deformation of the foundation when the swelling soil loses water and shrinks.

[0061] The horizontal overlapping reinforcement body and the vertical pile foundation reinforcement body constrain and support each other, forming a stable skeleton structure, which is similar to a bidirectional reinforcement composite foundation. The skeleton structure constrains the swelling and shrinkage deformation of the soil body, improves the bearing capacity of the soil body in both horizontal and vertical directions, and prevents the lateral and vertical deformation of the foundation soil body, thereby reducing the uneven settlement of the foundation.

[0062] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application.

Claims

1. A method of reinforcing and raising a building on an expansive soil foundation, characterized by, The method comprises the following steps: forming a curtain wall (21), drilling holes vertically downwards around the base slab of the building, drilling into the non-swelling soil layer to form a plurality of spaced curtain holes (1), grouting into the curtain holes (1), the grouting range of adjacent two curtain holes (1) overlapping each other to form a closed curtain wall (21); forming a shallow reinforcement body (22), drilling a reinforcement grouting hole (2) downwards on the top of the raft, grouting and reinforcing the shallow swelling soil foundation to form a shallow reinforcement body (22); forming a horizontal lapping reinforcement body (23), arranging a plurality of horizontal lapping reinforcement bodies (23) extending along the horizontal direction in the swelling soil layer between the curtain walls (21) on the opposite sides; forming a vertical pile foundation reinforcement body (24), arranging a plurality of vertical pile foundation reinforcement bodies (24) extending along the vertical direction in the curtain wall (21), and each of the vertical pile foundation reinforcement bodies (24) intersects with the corresponding horizontal lapping reinforcement body (23) on the path; lifting grouting, arranging a lifting hole in the curtain wall (21), and performing pressure grouting from bottom to top at the bottom of the lifting hole to realize building lifting; each of the horizontal lapping reinforcement bodies (23) is arranged on the curtain walls (21) on the two sides in a vertically spaced staggered manner, and the free end of each of the horizontal lapping reinforcement bodies (23) overlaps when projected along the vertical direction; each of the vertical pile foundation reinforcement bodies (24) penetrates through the corresponding horizontal lapping reinforcement body (23) and connects with the horizontal lapping reinforcement body (23) after intersection, and the end portion extends into the non-swelling soil layer; pressure grouting is performed at the bottom of the lifting hole, the grouting pipe stops grouting when passing through the range of the horizontal lapping reinforcement body (23), and continues grouting after the grouting pipe leaves the range of the horizontal lapping reinforcement body (23).

2. The method of claim 1, wherein, The drill-grouting integrated machine is used to sequentially grout into the curtain hole (1) in multiple segments in the vertical direction, the grout is sprayed from the nozzle of the grouting pipe and then pressed into the surrounding soil, and solidified within 30-60s to form the curtain wall (21). The grouting pressure in the curtain hole (1) is 0.3-0.5Mpa, and the thickness of the curtain wall (21) is 3m.

3. The method of claim 1, wherein, The drill-grouting integrated machine is used to grout into the reinforcement grouting hole (2) in multiple segments in the vertical direction by using the forward grouting method, the grout is sprayed from the nozzle of the grouting pipe and then solidified within 30-60s, and the depth of each forward advance is 30-50cm.

4. The method of claim 1, wherein, The drill-grouting integrated machine is used to perform pressure grouting at the bottom of the lifting hole and segmented backward grouting to lift the building.

5. The method according to any one of claims 1 to 4, wherein During the pressure grouting process of the lifting hole, the grouting pressure is greater than the reference pressure and less than 1.8 times of the reference pressure, wherein the reference pressure = the weight of the building / the area of the raft.

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