Method for determining grouting amount during lifting of independent foundation of building

Abstract

The invention discloses a method for determining grouting amount during lifting of an independent foundation of a building, which comprises the following steps: an extended foundation before lifting is an independent foundation, a shallow reinforcing layer is constructed below the independent foundation, a deep reinforcing layer is constructed below the shallow reinforcing layer, a lifting layer is arranged between the shallow reinforcing layer and the deep reinforcing layer, and the original extended foundation is lifted through grouting; according to the method, the shallow reinforcement grouting amount, the deep reinforcement grouting amount and the middle reinforcement lifting grouting amount are deduced and calculated according to the porosity of the soil layer and by introducing correlation coefficients, then the total grouting amount is obtained, and theoretical research of grouting is promoted. The theoretical formula of the grouting amount is deduced through calculation, quantifiable indexes are provided, and economic and efficient guiding significance is achieved for the actual grouting project construction scheme and grouting parameter design.

Description

Technical Field

[0001] The invention relates to the technical field of grouting reinforcement and lifting under an independent foundation, and in particular to a method for determining the grouting amount when the independent foundation of a building is lifted. Background Art

[0002] As people's requirements for living environment increase, more and more supporting facilities are built around the community. Supporting facilities are usually low-rise buildings, frame structures, and independent foundations. Compared with raft foundations and box foundations, the interaction between independent foundations is smaller, and the settlement of each independent foundation mainly depends on the load of a single column and the properties of the corresponding soil layer. The commonly used method for lifting buildings is grouting, but it is unknown how much grouting can be used to lift the foundation. If the grouting amount is too little, it cannot be lifted. If the grouting amount is too much, it will cause waste, or the building will be lifted more crooked due to inappropriate grouting amount. Therefore, we need to find a theoretical method to qualitatively and quantitatively study the grouting amount. Summary of the invention

[0003] The invention provides a method for determining the grouting amount when the independent foundation of a building is lifted, which is used to solve the technical problems of qualitative and quantitative determination of the grouting amount under the independent foundation.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for determining the amount of grouting when lifting an independent foundation of a building, wherein the extended foundation is an independent foundation before lifting, a shallow reinforcement layer is applied below the independent foundation, a deep reinforcement layer is applied below the shallow reinforcement layer, a lifting layer is provided between the shallow reinforcement layer and the deep reinforcement layer, and the original extended foundation is lifted by grouting; the specific steps are as follows:

[0006] Step 1: Survey the soil layer to be reinforced and lifted under the extended foundation before lifting, and clarify the soil quality and porosity of each soil layer, as well as the foundation settlement value required for lifting;

[0007] Step 2: Determine the thickness of the shallow reinforcement layer, deep reinforcement layer and lifting layer, and define the reinforcement boundary according to the height to be lifted;

[0008] Step 3: Determine the grouting amount of the shallow reinforcement layer based on the thickness of the shallow reinforcement layer, the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate; and determine the grouting amount of the deep reinforcement layer based on the thickness of the deep reinforcement layer, the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate;

[0009] Step 4: Based on the thickness of the lifting layer, the foundation settlement value, the porosity of the soil layer corresponding to the lifting layer, the area of ​​the soil layer in the grouting lifting range, the grouting pore filling rate and the slurry volume effective coefficient, comprehensively determine the grouting amount required for the lifting layer.

[0010] Step 5: Then, the grouting volumes corresponding to the shallow reinforcement layer, the lifting layer, and the deep reinforcement layer are combined to obtain the total grouting volume when the independent foundation of the building is lifted.

[0011] Furthermore, when investigating the soil layer in step 1, the soil layer is stratified according to the natural soil layer at the bottom of the extended foundation before lifting; the porosity n is obtained according to the following formula through the measured porosity ratio e:

[0012]

[0013] e is the porosity ratio, which is the ratio of the pore volume in the soil to the volume of its solid particles, and can be obtained from the geological survey data of the survey unit.

[0014] Furthermore, for the determination of the porosity n in the shallow reinforcement layer, deep reinforcement layer and uplift layer, if it corresponds to a natural soil layer, it is the porosity of the natural soil layer; if it corresponds to two or more natural soil layers, it is determined by the weighted average of the proportion of the thickness of each natural soil layer in the corresponding shallow reinforcement layer, deep reinforcement layer or uplift layer.

[0015] Furthermore, the required foundation settlement value ΔS is the height difference between the extended foundation base before lifting and the extended foundation base after lifting. Furthermore, the shallow reinforcement layer is used to reinforce the soft soil layer below the foundation bottom, fill the base pores, improve the strength and stiffness of the area, coordinate the force of the foundation bottom plate and ensure the uniformity of the lifting effect; the reinforcement thickness of the shallow reinforcement layer is 1.5 to 3 meters.

[0016] Deep reinforcement ensures that the foundation has sufficient bearing capacity and can provide a bearing layer foundation for subsequent lifting. When the original bearing layer of the foundation is deep, the reinforcement thickness is 3 to 5 meters; when the original bearing layer of the foundation is shallow, the reinforcement is to 1 meter below the bearing layer.

[0017] Furthermore, the grouting amount of the shallow reinforcement layer is calculated by the following formula:

[0018] Q1=Ah1n1ξ1

[0019] Where: Q1 is the shallow reinforcement grouting volume (m 3 ); h1 is the thickness of the shallow reinforcement soil layer (m); n1 is the porosity of the shallow reinforcement soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ1 is the grouting pore filling rate, which is between 0.7 and 0.9.

[0020] Furthermore, the soil layer area A within the grouting reinforcement range is calculated by the following formula:

[0021] A=(a1+2c)×(b1+2c)

[0022] In the formula: a1 is the width of the independent foundation, b1 is the length of the independent foundation, and c is the distance from the foundation edge to the reinforcement boundary.

[0023] Furthermore, the grouting amount of the deep reinforcement layer is calculated by the following formula:

[0024] Q3=Ah3n3ξ3

[0025] Where: Q3 is the deep reinforcement grouting volume (m 3 ); h3 is the thickness of the deep reinforcement soil layer (m); n3 is the porosity of the deep reinforcement soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ3 is the grouting pore filling rate, which is between 0.7 and 0.9.

[0026] Furthermore, the grouting volume of the lifting layer is calculated by the following formula:

[0027]

[0028] Where: Q2 is the grouting volume of the lifting layer (m 3 ); h2 is the thickness of the lifted soil layer (m); n2 is the porosity of the lifted soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ2 is the grouting pore filling rate, which is 0.7~0.9;γ is the slurry volume effective coefficient, which is 0.2~0.5;ΔS is the basic settlement value (m).

[0029] Furthermore, the total grouting volume Q when the independent foundation of the building is lifted 总 ,

[0030] Q 总 =(1+μ)(Q1+Q2+Q3);

[0031] Where: μ is the loss rate of slurry, ranging from 10% to 30%.

[0032] The beneficial effects of the present invention are embodied in:

[0033] The present invention calculates the shallow reinforcement grouting volume, deep reinforcement grouting volume and intermediate layer reinforcement lifting grouting volume based on the soil layer porosity and introduces the correlation coefficient, and then obtains the total grouting volume, which promotes the theoretical research of grouting. By calculating and deriving the theoretical formula of the grouting volume, a quantifiable indicator is provided, which has an economical and efficient guiding significance for the actual grouting project construction plan and grouting parameter design. The formula derived by the present invention is suitable for the grouting lifting of independent foundations, which ensures the quality of independent foundations after grouting reinforcement and avoids the risks of secondary settlement or excessive grouting after the grouting construction is completed.

[0034] Other features and advantages of the present invention will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present invention; the main purpose and other advantages of the present invention may be realized and obtained through the solutions particularly pointed out in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the original building and the expanded building;

[0036] Figure 2 It is a schematic diagram of the extended foundation, columns and reinforced boundary structure;

[0037] Figure 3 It is a schematic diagram of the distribution of shallow reinforcement layer, uplift layer and deep reinforcement layer;

[0038] Figure 4 This is a schematic diagram of the layers of the independent foundation before grouting and lifting;

[0039] Figure 5 This is a schematic diagram of each layer of the independent foundation after grouting and lifting.

[0040] Figure numbers: 1-original building, 2-extended building, 3-extended foundation before lifting, 4-reinforced boundary, 5-columns before lifting, 6-shallow reinforcement layer, 7-lifting layer, 8-deep reinforcement layer, 9-columns after lifting, 10-extended foundation after lifting. DETAILED DESCRIPTION

[0041] Taking the expansion building of a certain project as an example, the expanded restaurant has two floors. The expansion part is 18.800m long from east to west and 28.740m wide from north to south. The first floor is 4.200m high and the second floor is 3.600m high. The foundation of the restaurant is an independent foundation under the column, and the bottom elevation of the foundation is -1.2m. The foundation of the expansion part is cantilevered at the junction with the original building. The design grade of the foundation is Class C. The foundation size of the expansion foundation 3 before lifting is 3m×2m. The overall settlement of the expansion building 2 is about 3 to 5cm, and wide cracks have appeared in the wall. The restaurant glass is also damaged. The uneven settlement has affected the overall safety of the building. In order to ensure the normal use safety of the restaurant, it is necessary and urgent to treat the foundation of the building. See the floor plan of the expanded restaurant. Figure 1 , the calculation is carried out taking the independent foundation with the largest settlement as an example.

[0042] like Figures 1 to 5 As shown, a shallow reinforcement layer 6 is applied below the independent foundation, a deep reinforcement layer 8 is applied below the shallow reinforcement layer 6, a lifting layer 7 is arranged between the shallow reinforcement layer 6 and the deep reinforcement layer 8, and the original extended foundation is lifted by grouting.

[0043] The specific steps for determining the grouting volume when raising the independent foundation of a building are as follows: Step 1: Survey the soil layer to be reinforced and raised below the extended foundation 3 before raising, and clarify the soil quality and porosity of each soil layer, as well as the foundation settlement value required for raising.

[0044] When investigating the soil layer in step 1, the layers are divided according to the natural soil layer at the bottom of the extended foundation 3 before lifting; the porosity n is obtained according to the following formula through the measured porosity ratio e:

[0045]

[0046] e is the porosity ratio, which is the ratio of the pore volume in the soil to the volume of its solid particles, and can be obtained from the geological survey data of the survey unit. The specific data of the porosity ratio and porosity of each soil layer in this embodiment are shown in the following table, where the plain fill soil above the expansion foundation 3 before lifting is not recorded.

[0047] Soil layer ① Plain fill ②Silty soil ③Silty clay ④Silty clay ⑤Silty soil ■Porosity ratio e - 0.950 0.760 0.700 0.680 ■Porosity n - 0.49 0.43 0.41 0.40

[0048] Among them, when applied, for the determination of the porosity n in the shallow reinforcement layer 6, deep reinforcement layer 8 and lifting layer 7, if it corresponds to a natural soil layer, it is the porosity of the natural soil layer; if it corresponds to two or more natural soil layers, it is determined by the weighted average of the proportion of the thickness of each natural soil layer in the corresponding shallow reinforcement layer 6, deep reinforcement layer 8 or lifting layer 7. The required foundation settlement value ΔS is the height difference between the base of the extended foundation 3 before lifting and the base of the extended foundation 10 after lifting, and this embodiment takes 0.05m. Step 2, determine the thickness of the shallow reinforcement layer 6, deep reinforcement layer 8 and lifting layer 7, and define the reinforcement boundary 4 according to the height to be lifted.

[0049] Among them, the shallow reinforcement layer 6 is used to reinforce the soft soil layer below the foundation bottom, fill the base pores, improve the strength and rigidity of the area, make the foundation bottom plate force coordinated and ensure the uniformity of the lifting effect; the reinforcement thickness of the shallow reinforcement layer 6 is 1.5 to 3 meters, and h1 in this embodiment is 2 meters thick for the shallow reinforcement soil layer. Deep reinforcement ensures that the foundation has sufficient bearing capacity and can provide a bearing layer foundation for subsequent lifting. When the original bearing layer of the foundation is deep, the reinforcement thickness is 3 to 5 meters; h3 is the thickness of the deep reinforcement soil layer, which is 3 meters; when the original bearing layer of the foundation is shallow, it is reinforced to 1 meter below the bearing layer.

[0050] In this embodiment, h2 is the thickness of the lifted soil layer and is 1m, and the distance between the reinforcement boundary 4 and the pre-lifted expansion foundation 3 is 0.5m. Step 3: Determine the grouting amount of the shallow reinforcement layer based on the thickness of the shallow reinforcement layer 6, the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate; and determine the grouting amount of the deep reinforcement layer 8 based on the thickness of the deep reinforcement layer 8, the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate.

[0051] The grouting amount of the shallow reinforcement layer 6 is calculated by the following formula:

[0052] Q1=Ah1n1ξ1=12×2×0.49×0.9=10.58m 3

[0053] Where: Q1 is the shallow reinforcement grouting volume m 3 ; h1 is the thickness of the shallow reinforcement soil layer m; n1 is the porosity of the shallow reinforcement soil layer, which corresponds to the porosity of the ② stratum and is taken as 0.49; A is the area of ​​the soil layer within the grouting reinforcement range m 2 ; ξ1 is the grouting pore filling rate, which is taken as 0.9.

[0054] Among them, the soil layer area A within the grouting reinforcement range is calculated by the following formula:

[0055] A=(a1+2c)×(b1+2c)=2+1×(3+1)=12m 2

[0056] Where: a1 is the width of the independent foundation, b1 is the length of the independent foundation, and c is the distance from the foundation edge to the reinforcement boundary 4, which is 0.5m. The grouting volume of the deep reinforcement layer 8 is calculated by the following formula:

[0057] Q3=Ah3n3ξ3=12×3×0.42×0.8=12.10m 3

[0058] Where: Q3 is the deep reinforcement grouting volume m 3 ; h3 is the thickness of the deep reinforcement soil layer m; n3 is the porosity of the deep reinforcement soil layer, corresponding to the strata where the ③ and ④ soil layers each occupy half the thickness of the deep reinforcement layer 8, which is 0.5×0.43+0.5×0.41=0.42; A is the area of ​​the soil layer within the grouting reinforcement range m 2 ; ξ3 is the grouting pore filling rate, which is taken as 0.8.

[0059] Step 4: Based on the thickness of the lifting layer 7, the foundation settlement value, the porosity of the soil layer corresponding to the lifting layer 7, the area of ​​the soil layer in the grouting lifting range, the grouting pore filling rate and the slurry volume effective coefficient, the grouting amount required for the lifting layer 7 is comprehensively determined. The grouting amount of the lifting layer 7 is calculated by the following formula:

[0060]

[0061] Where: Q2 is the grouting volume of the lifting layer m 3 ; h2 is the thickness of the lifted soil layer m; n2 is the porosity of the lifted soil layer, which corresponds to the porosity of the ③ stratum and is taken as 0.43; A is the area of ​​the soil layer within the grouting reinforcement range m 2; ξ2 is the grouting pore filling rate, which is taken as 0.85; γ is the slurry volume effective coefficient, which is taken as 0.2; ΔS is the basic settlement value m.

[0062] Step 5: Then, the grouting volumes corresponding to the shallow reinforcement layer 6, the lifting layer 7 and the deep reinforcement layer 8 are combined to obtain the total grouting volume when the independent foundation of the building is lifted.

[0063] Total grouting volume Q when the independent foundation of the building is lifted 总 ,

[0064] Q 总 =Q 总 =(1+μ)(Q1+Q2+Q3)=(1+15%)(10.58+12.10+7.39)=34.58m 3

[0065] Where: μ is the loss rate of slurry, which is taken as 15%.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that a technician familiar with the technical field thinks of within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for determining the grouting amount when the independent foundation of a building is lifted, characterized in that: The extended foundation (3) before lifting is an independent foundation, a shallow reinforcement layer (6) is applied below the independent foundation, a deep reinforcement layer (8) is applied below the shallow reinforcement layer (6), a lifting layer (7) is provided between the shallow reinforcement layer (6) and the deep reinforcement layer (8), and the original extended foundation is lifted by grouting; the specific steps are as follows: Step 1: Survey the soil layer to be reinforced and lifted below the extended foundation (3) before lifting, and clarify the soil quality and porosity of each soil layer, as well as the foundation settlement value required for lifting; Step 2: determine the thickness of the shallow reinforcement layer (6), the deep reinforcement layer (8) and the lifting layer (7), and define the reinforcement boundary (4) according to the height to be lifted; Step 3: Determine the grouting amount of the shallow reinforcement layer based on the thickness of the shallow reinforcement layer (6), the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate; and determine the grouting amount of the deep reinforcement layer (8) based on the thickness of the deep reinforcement layer (8), the porosity of the corresponding soil layer, the area of ​​the soil layer in the grouting reinforcement range, and the grouting pore filling rate; Step 4: Based on the thickness of the soil layer of the lifting layer (7), the foundation settlement value, the porosity of the soil layer corresponding to the lifting layer (7), the area of ​​the soil layer in the grouting lifting range, the grouting pore filling rate and the grouting volume effective coefficient, the grouting amount required for the lifting layer (7) is comprehensively determined. Step 5: Then, the grouting volumes corresponding to the shallow reinforcement layer (6), the lifting layer (7) and the deep reinforcement layer (8) are combined to obtain the total grouting volume when the independent foundation of the building is lifted.

2. A method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: When investigating the soil layer in step 1, the layers are divided according to the natural soil layer at the bottom of the extended foundation (3) before lifting; the porosity n is obtained by the measured porosity ratio e according to the following formula: e is the porosity ratio, which is the ratio of the pore volume in the soil to the volume of its solid particles, and can be obtained from the geological survey data of the survey unit.

3. The method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: Regarding the determination of the porosity n in the shallow reinforcement layer (6), the deep reinforcement layer (8) and the lifting layer (7), if it corresponds to a natural soil layer, then it is the porosity of the natural soil layer; if it corresponds to two or more natural soil layers, it is determined by the weighted average of the proportion of the thickness of each natural soil layer in the corresponding shallow reinforcement layer (6), deep reinforcement layer (8) or lifting layer (7).

4. A method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: The required foundation settlement value ΔS for lifting is the height difference between the base of the extended foundation (3) before lifting and the base of the extended foundation (10) after lifting.

5. The method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: The shallow reinforcement layer (6) is used to reinforce the soft soil layer below the foundation bottom, fill the base pores, improve the strength and rigidity of the area, coordinate the force of the foundation bottom plate and ensure the uniformity of the lifting effect; the reinforcement thickness of the shallow reinforcement layer (6) is 1.5 to 3 meters; Deep reinforcement ensures that the foundation has sufficient bearing capacity and can provide a bearing layer foundation for subsequent uplift; when the original bearing layer of the foundation is deep, the reinforcement thickness is 3 to 5 meters; when the original bearing layer of the foundation is shallow, the reinforcement is to 1 meter below the bearing layer.

6. A method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: The grouting volume of the shallow reinforcement layer (6) is calculated by the following formula: Q1=Ah1n1ξ1 Where: Q1 is the shallow reinforcement grouting volume (m 3 ); h1 is the thickness of the shallow reinforcement soil layer (m); n1 is the porosity of the shallow reinforcement soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ1 is the grouting pore filling rate, which is between 0.7 and 0.

9.

7. A method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: in, The soil layer area A within the grouting reinforcement range is calculated using the following formula: A=(a1+2c)×(b1+2c) In the formula: a1 is the width of the independent foundation, b1 is the length of the independent foundation, and c is the distance from the foundation edge to the reinforcement boundary.

8. The method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: The grouting amount of the deep reinforcement layer (8) is calculated by the following formula: Q3=Ah3n3ξ3 Where: Q3 is the deep reinforcement grouting volume (m 3 ); h3 is the thickness of the deep reinforcement soil layer (m); n3 is the porosity of the deep reinforcement soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ3 is the grouting pore filling rate, which is between 0.7 and 0.

9.

9. A method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: The grouting volume of the lifting layer (7) is calculated by the following formula: Where: Q2 is the grouting volume of the lifting layer (m 3 ); h2 is the thickness of the lifted soil layer (m); n2 is the porosity of the lifted soil layer; A is the area of ​​the soil layer within the grouting reinforcement range (m 2 );ξ2 is the grouting pore filling rate, which is 0.7~0.9;γ is the slurry volume effective coefficient, which is 0.2~0.5;ΔS is the basic settlement value (m).

10. The method for determining the grouting amount when the independent foundation of a building is lifted as claimed in claim 1, characterized in that: Total grouting volume Q when the independent foundation of the building is lifted 总 , Qtotal = (1 + μ)(Q1 + Q2 + Q3); Where: μ is the loss rate of slurry, ranging from 10% to 30%.

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