Method for calculating settlement of adjacent high-rise buildings in canal foundation pit excavation process

Abstract

The invention discloses a method for calculating settlement of an adjacent high-rise building in a canal foundation pit excavation process. The method comprises the following steps: firstly, calculating ground surface settlement caused by foundation pit excavation under the condition of considering a building; then considering the underground water level change, and calculating the settlement caused by the underground water level change; superposing the settlement values of the ground surface settlement and the underground water level change, and drawing a settlement curve graph considering whether the underground water level change exists or not; analyzing inclinometry data of the high-rise building and settlement data of the building bottom close to the ground, and drawing a settlement curve graph of the high-rise building when the deep foundation pit is excavated under the condition that the canal water level changes; finally, through data difference value comparison and error analysis, it is determined that the error of a calculation result of the method is controlled within a certain range, and the settlement value can be predicted more accurately. According to the calculation formula, the self load of the building is considered, meanwhile, the influence of underground water level changes on building settlement caused by foundation pit excavation is also considered, the calculated settlement amount is more accurate, and errors are smaller.

Description

Technical Field

[0001] The invention relates to the technical field of settlement calculation, and in particular to a method for calculating the settlement of adjacent high-rise buildings during a canal foundation pit excavation process. Background Art

[0002] With the rapid development of urbanization, the development of underground space has been increasing. It is a common phenomenon to excavate foundation pits in areas near buildings in cities. The loss of soil caused by foundation pit excavation will lead to surface subsidence, and the buildings within the settlement trough will be affected by the surface subsidence, plus the settlement caused by the building's own gravity. Finally, the total settlement is reflected by the building.

[0003] The existing technology basically considers the building's own load and the settlement calculation under different soil conditions, but lacks consideration of the settlement caused by changes in groundwater levels. During the foundation pit excavation process based on the canal background, considering that there was a lot of rainfall during the excavation process, the water level around the river channel also soared, causing the groundwater level to increase. The settlement caused by changes in the groundwater level cannot be ignored.

[0004] The defects of the existing settlement calculation method are:

[0005] 1. Patent document CN106777974B discloses a method for calculating the settlement of surrounding buildings caused by foundation pit excavation. However, the settlement calculation method in the patent document does not consider the impact of changes in groundwater levels on the settlement of nearby buildings.

[0006] 2. The existing method for calculating the settlement of buildings near foundation pits does not consider the analysis of the inclined side data of the building and the settlement data of the bottom of the building close to the ground, and does not consider the deformation of the building;

[0007] 3. The existing building settlement calculation methods do not consider the spatial distribution of soil deformation outside the pit, that is, they do not consider the relationship between the distance between the settlement point and the foundation pit and the actual settlement;

[0008] 4. Patent document CN108647474B discloses a method for calculating the settlement of soil at the edge of a foundation pit of a pile-supported retaining structure. However, the settlement calculation method in the patent document is relatively complex, requires many parameters, and requires a large amount of work in measuring parameters and calculations. Summary of the invention

[0009] The purpose of the present invention is to provide a method for calculating the settlement of adjacent high-rise buildings during the excavation of a canal foundation pit, so as to solve the problems raised in the above-mentioned background technology.

[0010] To achieve the above object, the present invention provides the following technical solution: The present invention provides a method for calculating the settlement of adjacent high-rise buildings during the excavation of a canal foundation pit, and the specific steps are as follows:

[0011] Step S1, considering the building, calculating the surface settlement caused by the foundation pit excavation, and calculating the displacement of the building. The calculation formula of the surface settlement caused by the foundation pit excavation is:

[0012]

[0013] Where: S is the settlement, F is the building load, v is Poisson's ratio, E is the elastic modulus of the soil, h is the depth of the foundation pit, α is the attenuation factor, and x is the distance from the calculated settlement point to the foundation pit;

[0014] Step S2: Considering the change in groundwater level caused by the excavation of the canal close to the original river channel and the change in water level around the canal due to rainfall, the settlement caused by the groundwater change is calculated using the following formula:

[0015]

[0016] Where: S w is the settlement caused by water level change (m), K is the soil permeability coefficient, h1 and h2 are the water level heights before and after the change (m), L is the length of the water flow path (m), and β is the correction coefficient;

[0017] Step S3, superimposing the settlement values ​​of the surface settlement and the groundwater level change, and drawing a settlement curve diagram of layered excavation at different time periods considering whether there is a groundwater level change;

[0018] Step S4, analyzing the inclinometric data of the high-rise building and the settlement data of the bottom of the building close to the ground, and drawing a settlement curve of the high-rise building when the deep foundation pit is excavated under the condition of canal water level changes;

[0019] Step S5, the calculated building settlement cannot be completely consistent with the measured settlement value. Therefore, by comparing the difference between the calculated value and the measured value and performing error analysis, it is determined that the result obtained by the calculation method can be controlled within a certain range with the actual error, and can more accurately predict the settlement value of adjacent high-rise buildings caused by the excavation of the canal foundation pit.

[0020] Preferably, the attenuation factor α describes the attenuation degree of the settlement caused by the load in the depth direction, and the attenuation factor α is related to the characteristics of the soil and the load position.

[0021] Preferably, in step S3, the superimposed sedimentation value is S 总 , the specific formula is:

[0022] S 总=S+S w

[0023] Among them, S 总 is the total settlement of the building taking groundwater into account.

[0024] Preferably, in step S4, the specific analysis method for analyzing the inclinometer data of the high-rise building and the settlement data of the bottom of the building close to the ground is: comparing and analyzing whether there is a deviation in the settlement of the high-rise building, and whether the relationship between the settlement of the ground and the settlement of the top of the building is consistent.

[0025] Preferably, in step S4, the oblique side data of the high-rise building includes tilt observation data and displacement observation data.

[0026] Preferably, in step S4, the oblique side data of the high-rise building is obtained and updated through regular measurements by staff.

[0027] Preferably, the tilt observation data is obtained by measuring with a digital display inclinometer.

[0028] Preferably, the displacement observation data includes X-axis horizontal direction displacement data and Y-axis horizontal direction displacement data.

[0029] Preferably, the X-axis horizontal displacement data and the Y-axis horizontal displacement data are both obtained by measuring with a fully automatic total station.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The calculation formula of the present invention not only considers the load of the building itself, but also considers the influence of the change of groundwater level caused by rainfall and other conditions on the settlement of the building caused by foundation pit excavation, so that the calculation formula can adapt to the process of canal foundation pit excavation. Considering the change of groundwater level makes the application scope of the calculation formula wider, and the higher the degree of change of groundwater level, the more accurate the settlement calculated by the calculation method is and the smaller the error is.

[0032] 2. The present invention evaluates whether there is a deviation in the settlement of a high-rise building and whether the relationship between the settlement of the ground and the settlement of the top is consistent by comparative analysis of the inclinometric data of the high-rise building and the settlement data of the bottom of the building close to the ground; comparative analysis of the data can help to timely monitor the deformation of the building, evaluate the impact of foundation pit excavation on the stability of the building, correct the settlement calculation model, formulate a scientific excavation plan, and make dynamic adjustments based on real-time data, thereby minimizing the risk of settlement and ensuring the structural safety of the building.

[0033] 3. The calculation formula of the present invention includes the distance between the position of the calculated settlement point and the foundation pit as x, so that the calculation result of the calculation formula can change according to the change of the distance between the specific foundation pit and the calculated settlement point, which means that the calculation formula takes into account the distribution of soil deformation caused by the foundation pit in space, thereby further improving the accuracy of the calculation formula.

[0034] 4. The calculation method of the present invention is simple, requires fewer parameters, and considers more comprehensive influencing factors, so that the final calculation result of the present invention has a smaller error, a more accurate result, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A diagram of surface subsidence in the case of groundwater in an embodiment of the present invention;

[0036] Figure 2 This is a diagram of surface settlement in the absence of groundwater in an embodiment of the present invention;

[0037] Figure 3 It is a horizontal displacement diagram of the X-axis of a building without groundwater in an embodiment of the present invention;

[0038] Figure 4 It is a horizontal displacement diagram of the Y axis of a building without groundwater in an embodiment of the present invention;

[0039] Figure 5 For the embodiment of the present invention, there is a horizontal displacement diagram of the groundwater structure in the X-axis direction;

[0040] Figure 6 An embodiment of the present invention includes a horizontal displacement diagram of a groundwater structure along the Y axis. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The technical solution of the present invention is further described below in conjunction with the accompanying drawings:

[0043] See also Figures 1 to 6 The present invention provides a specific embodiment of a method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation, comprising the following steps:

[0044] Step S1, considering the building, calculating the surface settlement caused by the foundation pit excavation, and calculating the displacement of the building. The calculation formula of the surface settlement caused by the foundation pit excavation is:

[0045]

[0046] Where: S is the settlement, F is the building load, v is Poisson's ratio, E is the elastic modulus of the soil, h is the depth of the foundation pit, α is the attenuation factor, and x is the distance from the settlement point to the foundation pit;

[0047] Specifically, this calculation method is based on the Boussinesq theory, establishes a surface settlement model caused by foundation pit excavation, and uses the existing empirical relationship to improve the existing calculation method. Among them, S is the surface settlement caused by foundation pit excavation, the unit is meter, the building load F, v Poisson's ratio refers to the ratio of the lateral normal strain to the axial normal strain when the material is subjected to unidirectional tension or compression, also called the lateral deformation coefficient, which is an elastic constant reflecting the lateral deformation of the material, E is the elastic modulus of the soil where the foundation pit is located, which refers to the ratio between the strain of the soil and the external force when the soil is subjected to external force, h is the depth of the foundation pit to be excavated, the unit is meter, the attenuation factor α describes the attenuation degree of the settlement caused by the load in the depth direction, which is usually related to the characteristics of the soil and the load position, and x is the distance from the location of the settlement calculation point to the foundation pit;

[0048] Specifically, before calculating the ground settlement caused by foundation pit excavation, the building is considered.

[0049] Step S2: Considering the change in groundwater level caused by the excavation of the canal close to the original river channel and the change in water level around the canal due to rainfall, the settlement caused by the groundwater change is calculated using the following formula:

[0050]

[0051] Where: S w is the settlement caused by water level change (m), K is the soil permeability coefficient, h1 and h2 are the water level heights before and after the change (m), L is the length of the water flow path (m), and β is the correction coefficient;

[0052] Specifically, h1 is the height of the water level after the change (m), h2 is the height of the water level before the change (m), h1-h2 is the height of the water level change, and L is the length of the groundwater flow path (m);

[0053] Step S3, superimposing the settlement values ​​of the surface settlement and the groundwater level change, and drawing a settlement curve diagram of layered excavation at different time periods considering whether there is a groundwater level change;

[0054] Among them, S 总 =S+S w ;

[0055] Specifically, without considering groundwater, the surface subsidence curve is as follows: Figure 1 As shown in Figure 2, considering groundwater, the surface settlement curve is as follows: Figure 2 As shown;

[0056] Step S4, analyzing the inclinometric data of the high-rise building and the settlement data of the bottom of the building close to the ground, and drawing a settlement curve of the high-rise building when the deep foundation pit is excavated under the condition of canal water level changes;

[0057] Specifically, the specific analysis method for analyzing the inclinometer data installed on high-rise buildings and the settlement data near the ground at the bottom of the building is: comparative analysis of whether there is a deviation in the settlement of the high-rise building, and whether the relationship between the settlement of the ground and the settlement of the top is consistent; through comparative analysis of the data, it can help to timely monitor the deformation of the building, evaluate the impact of foundation pit excavation on the stability of the building, correct the settlement calculation model, formulate a scientific excavation plan, and make dynamic adjustments based on real-time data, so as to minimize the risk of settlement and ensure the structural safety of the building;

[0058] The oblique side data of high-rise buildings include inclination observation data and displacement observation data. The oblique side data of high-rise buildings are obtained and updated through regular measurements by staff. Staff can go to the observation point for measurement every other day. The inclination observation data are obtained through digital display inclinometer measurement, such as CX-03 digital display tester; the displacement observation data include X-axis horizontal displacement data and Y-axis horizontal displacement data, and the X-axis horizontal displacement data and the Y-axis horizontal displacement data are both obtained through full-automatic total station measurement;

[0059] Without considering the influence of groundwater on building settlement, the settlement curve of the building is as follows: Figure 3 and Figure 4 , Figure 3 and Figure 4 They are the displacement diagrams of the building in the horizontal direction of the X-axis and the horizontal direction of the Y-axis;

[0060] Considering the influence of groundwater on building settlement, the settlement curve of the building is as follows: Figure 5 and Figure 6 , Figure 5 and Figure 6 They are the displacement diagrams of the building in the horizontal direction of the X axis and the horizontal direction of the Y axis respectively;

[0061] The horizontal displacement of the building's X-axis represents the horizontal displacement of the building, and the unit symbol is m;

[0062] The horizontal displacement of the building's Y axis is the vertical displacement of the building, which is positive from the ground upwards and the unit symbol is m;

[0063] Step S5, the calculated building settlement cannot be completely consistent with the measured settlement value. Therefore, by comparing the difference between the calculated value and the measured value and performing error analysis, it is determined that the result obtained by the calculation method can be controlled within a certain range with the actual error, and can more accurately predict the settlement value of adjacent high-rise buildings caused by the excavation of the canal foundation pit.

[0064] The calculation formula of the present invention includes that the distance between the position of the calculated settlement point and the foundation pit is x, and x can change according to the distance between the specific foundation pit and the calculated settlement point, taking into account the distribution of soil deformation caused by the foundation pit in space, so as to explain that the soil deformation degrees of the building settlement calculation points at different distances outside the pit are different;

[0065] The calculation formula of the present invention includes the building's own load parameter F, which means that the calculation method of the present invention takes into account the influence of the building's own rigidity on the settlement;

[0066] The calculation formula of the present invention takes into account the influence of the groundwater level on the settlement, so that the calculation formula can adapt to the process of canal foundation pit excavation. Taking into account the change of the groundwater level makes the application range of the calculation formula wider, and the higher the degree of change of the groundwater level, the more accurate the settlement calculated by the calculation method is and the smaller the error is.

[0067] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation, the specific steps are as follows: Step S1, considering the building, calculating the surface settlement caused by the foundation pit excavation, and calculating the displacement of the building. The calculation formula of the surface settlement caused by the foundation pit excavation is: Where: S is the settlement, F is the building load, v is Poisson's ratio, E is the elastic modulus of the soil, h is the depth of the foundation pit, α is the attenuation factor, and x is the distance from the calculated settlement point to the foundation pit; Step S2: Considering the change in groundwater level caused by the excavation of the canal close to the original river channel and the change in water level around the canal due to rainfall, the settlement caused by the groundwater change is calculated using the following formula: Where: S w is the settlement caused by water level change (m), K is the soil permeability coefficient, h1 and h2 are the water level heights before and after the change (m), L is the length of the water flow path (m), and β is the correction coefficient; Step S3, superimposing the settlement values ​​of the surface settlement and the groundwater level change, and drawing a settlement curve diagram of layered excavation at different time periods considering whether there is a groundwater level change; Step S4, analyzing the inclinometric data of the high-rise building and the settlement data of the bottom of the building close to the ground, and drawing a settlement curve of the high-rise building when the deep foundation pit is excavated under the condition of canal water level changes; Step S5, the calculated building settlement cannot be completely consistent with the measured settlement value. Therefore, by comparing the difference between the calculated value and the measured value and performing error analysis, it is determined that the result obtained by the calculation method can be controlled within a certain range with the actual error, and can more accurately predict the settlement value of adjacent high-rise buildings caused by the excavation of the canal foundation pit.

2. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 1, characterized in that: The attenuation factor α describes the attenuation degree of the settlement caused by the load in the depth direction. The attenuation factor α is related to the characteristics of the soil and the load position.

3. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 1, characterized in that: In step S3, the superimposed sedimentation value is S 总 , the specific formula is: S 总 =S+S w Among them, S 总 is the total settlement of the building taking groundwater into account.

4. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 1, characterized in that: In step S4, the specific analysis method for analyzing the inclinometric data of the high-rise building and the settlement data of the bottom of the building close to the ground is: comparing and analyzing whether there is a deviation in the settlement of the high-rise building, and whether the relationship between the settlement of the ground and the settlement of the top of the building is consistent.

5. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 1, characterized in that: In step S4, the oblique side data of the high-rise building includes tilt observation data and displacement observation data.

6. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 1, characterized in that: In step S4, the oblique side data of the high-rise building is obtained and updated through regular measurements by staff.

7. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 5, characterized in that: The tilt observation data is obtained by measuring with a digital display inclinometer.

8. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 5, characterized in that: The displacement observation data includes X-axis horizontal direction displacement data and Y-axis horizontal direction displacement data.

9. The method for calculating the settlement of adjacent high-rise buildings during canal foundation pit excavation according to claim 8, characterized in that: The X-axis horizontal displacement data and the Y-axis horizontal displacement data are both obtained by measuring with a fully automatic total station.

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