A method and system for estimating foundation pit displacement in natural slope and soil nail wall support

Abstract

The present invention relates to the technical field of foundation pit support mechanical analysis, and provides a method and system for estimating foundation pit displacement in natural slope and soil nail wall support, the method comprising the following steps: according to the specified excavation working condition, determine the foundation pit depth, the thickness of different types of soil layers, and the horizontal displacement of retaining members at the bottom of the working condition pit; separate the soil layers of the foundation pit slope body from the top of the foundation pit to the foundation pit depth according to different types of soil layers, and each type of soil layer forms a strip of soil layers; determine the depth from the top of the foundation pit to the center of each strip of soil layers; calculate the horizontal reaction coefficient of each strip of soil layers according to a first preset formula; calculate the horizontal displacement of each strip of soil layers according to a second preset formula. Through the technical solution of the present invention, it is more in line with the changing law of natural slope and soil nail wall foundation pits, and can provide effective support for deformation early warning in foundation pit engineering design.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit support mechanical analysis, and in particular to a method and system for estimating foundation pit displacement in natural slope and soil nail wall support. Background Art

[0002] There is still a lack of relevant research work at home and abroad on the horizontal and vertical displacements of foundation pits with natural slope and soil nail wall support, and there are no corresponding normative standards. In conventional technology, it is generally estimated by empirical method with reference to monitoring data of similar projects. However, for foundation pits with complex geological conditions and surrounding environmental conditions, this empirical method will have a large deviation, which seriously affects the study of the actual change law of displacement deformation, and easily leads to unnecessary engineering waste and safety accidents. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, the purpose of the present invention is to provide a method and system for estimating the displacement of foundation pits in natural slope and soil nail wall support, and to use an elastic mechanics model to study the horizontal and vertical displacements of foundation pits in natural slope and soil nail wall support types. The method for estimating the displacement of foundation pits is more in line with the changing laws of natural slope and soil nail wall foundation pits, and can provide effective support for deformation early warning in foundation pit engineering design.

[0005] In order to achieve the above object, the technical solution of the first aspect of the present invention provides a method for estimating foundation pit displacement in natural slope and soil nail wall support, comprising the following steps:

[0006] Determine the foundation pit depth according to the specified excavation conditions , thickness of different types of soil layers , horizontal displacement of retaining elements at the bottom of the working pit ,in, , i=1,2,…,m;

[0007] The soil layers of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit are divided into different types of soil layers, and each type of soil layer forms Soil layer strips, among which, ≥1;

[0008] Determine the depth from the top of the foundation pit to the center of each soil strip , where j = 1, 2, ..., ;

[0009] According to the first preset formula, calculate the horizontal reaction coefficient of each soil strip , where the first preset formula is , where The horizontal reaction coefficient of the jth soil strip, which represents the i-th type soil layer, is Characterized as the proportional coefficient of the i-th type soil layer (MN / m 4 ), The center depth of the jth soil strip, which represents the i-th type soil layer, It is represented by the depth of the foundation pit under excavation conditions (m), Characterized as the internal friction angle of the i-th type soil layer, (°), Characterized by the cohesion of type i soil layer (kPa), It is characterized by the horizontal displacement of the retaining member at the bottom of the working pit (mm);

[0010] According to the second preset formula, the horizontal displacement of each soil strip is calculated. , where the second preset formula is , where The horizontal displacement of the jth soil strip in the i-th soil layer is represented by Characterized by the weight of the i-th type soil layer, Characterized as the active earth pressure coefficient of the i-th type soil layer, The upper depth of the jth soil strip, which represents the i-th type soil layer, The lower depth of the jth soil strip characterized by the i-th type soil layer.

[0011] Preferably, when the soil layer of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit is stratified according to different types of soil layers, each type of soil layer is stratified according to the specified soil layer strip thickness. If the remaining part is less than half of the specified soil layer strip thickness, it is merged into the adjacent soil layer strip. If the remaining part is not less than half of the specified soil layer strip thickness, its actual thickness is used as a soil layer strip.

[0012] Preferably, the active earth pressure coefficient of the i-th type soil layer is It is calculated by the following formula: .

[0013] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps:

[0014] The horizontal displacement of each type of soil layer is calculated by summing up the horizontal displacement of the soil strips corresponding to each type of soil layer. .

[0015] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps: According to the third preset formula, calculate the maximum horizontal displacement of the foundation pit slope top under the specified excavation condition , where the third preset formula is .

[0016] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps:

[0017] According to the maximum horizontal displacement of the foundation pit slope top under the specified excavation conditions According to the principle that the soil volume within the horizontal and vertical deformation ranges is equal, the vertical displacement at a certain point k outside the foundation pit is determined according to the fourth preset formula. , where it is assumed that the vertical displacement of the foundation pit is distributed in a triangular shape from the inside to the outside of the foundation pit. The fourth preset formula is , It is represented by the horizontal distance from a certain k point outside the foundation pit to the edge of the foundation pit.

[0018] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps: calculating the maximum vertical displacement of the foundation pit slope top under the specified excavation condition ,in, .

[0019] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps:

[0020] Determine the slope angle for each type of soil layer according to the specified excavation conditions , soil active failure rupture angle ,in, ;

[0021] According to the slope angle , soil active failure rupture angle , according to the fifth preset formula, calculate the horizontal displacement adjustment coefficient for each type of soil layer , where the fifth preset formula is:

[0022] ;

[0023] in, It is represented by the graphic area formed by the slope surface and the vertical surface in the i-th type soil layer. It is represented by the graphical area formed by the active fracture surface and the vertical surface in the i-th type soil layer.

[0024] According to the horizontal displacement adjustment coefficient of each type of soil layer, the horizontal displacement of each type of soil layer is adjusted and optimized respectively.

[0025] Preferably, the method for estimating foundation pit displacement in natural slope and soil nail wall support further comprises the following steps:

[0026] Determine the slope angle according to the specified excavation conditions , Active failure rupture angle of each type of soil layer ,in, ;

[0027] According to the slope angle , Active failure rupture angle of each type of soil layer , according to the sixth preset formula, calculate the horizontal and vertical displacement adjustment coefficients , where the sixth preset formula is:

[0028] ;

[0029] in, It is represented by the triangular area formed by the slope surface and the vertical surface in the entire foundation pit. It is represented by the polygonal area formed by the connecting line of active fracture surfaces of each soil layer in the entire foundation pit and the vertical surface.

[0030] According to the horizontal and vertical displacement adjustment coefficients, the maximum horizontal displacement of the foundation pit slope top and the maximum vertical displacement of the foundation pit slope top are adjusted and optimized respectively.

[0031] The technical solution of the second aspect of the present invention proposes a system for estimating foundation pit displacement in natural slope and soil nail wall support, on which a computer program is stored. When the computer program is executed by a processor, the steps of any one of the methods for estimating foundation pit displacement in natural slope and soil nail wall support proposed in the technical solution of the first aspect of the present invention are implemented.

[0032] The method and system for estimating foundation pit displacement in natural slope and soil nail wall support proposed by the present invention have the following beneficial technical effects:

[0033] (1) The method and system for estimating the displacement of foundation pits in natural slope and soil nail wall support proposed in the present invention are more in line with the changing laws of natural slope and soil nail wall foundation pits, can provide a reasonable basis for foundation pit design, avoid unnecessary engineering waste, and reduce the occurrence of safety accidents.

[0034] (2) The method and system for estimating foundation pit displacement in natural slope reduction and soil nail wall support proposed in the present invention can provide effective support for deformation early warning in foundation pit engineering design.

[0035] (3) The method and system for estimating foundation pit displacement in natural slope and soil nail wall support proposed in the present invention comprehensively considers the influence of factors such as soil layer parameters and slope gradient, and forms a unified setting standard, which can effectively avoid the disadvantages of different early warning displacements proposed by different design units and different stratum conditions.

[0036] (4) The method and system for estimating the displacement of foundation pits in natural slope and soil nail wall support proposed in the present invention adopt an elastic mechanics model, which is more in line with the actual displacement change law of foundation pits in natural slope and soil nail wall support types, and can effectively make up for the deficiency of the current specifications in not having a unified standard and principle for displacement warning.

[0037] (5) The method and system for estimating foundation pit displacement in natural slope and soil nail wall support proposed in the present invention have high accuracy in estimating foundation pit displacement, which has a slight deviation from the actual monitored displacement, with the deviation being around 10%.

[0038] Additional aspects and advantages of the present invention will be given in part in the following description and, in part, will be obvious from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0040] Figure 1 A schematic flow chart of a method for estimating foundation pit displacement in natural slope reduction and soil nail wall support according to an embodiment of the present invention is shown;

[0041] Figure 2 A schematic diagram of a foundation pit with soil strips divided according to specified excavation conditions is shown;

[0042] Figure 3 Shows the principle of foundation pit displacement adjustment Figure 1 ;

[0043] Figure 4 Shows the principle of foundation pit displacement adjustment Figure 2 ;

[0044] Figure 5 A schematic cross-sectional view of a foundation pit 1-1 is shown;

[0045] Figure 6 A schematic cross-sectional view of foundation pit 2-2 is shown;

[0046] Figure 7 A schematic cross-sectional view of foundation pit 3-3 is shown. DETAILED DESCRIPTION

[0047] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0048] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0049] Combine the following Figures 1 to 7 A method and system for estimating foundation pit displacement in natural slope reduction and soil nail wall support according to an embodiment of the present invention are specifically described.

[0050] like Figure 1 As shown, a method for estimating foundation pit displacement in natural slope and soil nail wall support according to an embodiment of the present invention includes the following steps:

[0051] S101, determine the foundation pit depth according to the specified excavation conditions , thickness of different types of soil layers , horizontal displacement of retaining elements at the bottom of the working pit ,in, , i=1,2,…,m;

[0052] It is the horizontal displacement of the retaining member at the bottom of the working pit. When the horizontal displacement here is not greater than 10mm, take 10mm.

[0053] S102, the soil layer of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit is divided into different types of soil layers, and each type of soil layer is formed Soil layer strips, among which, ≥1,

[0054] Specifically, when the soil layer of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit is stratified according to different types of soil layers, each type of soil layer is stratified according to the specified soil layer strip thickness. If the remaining part is less than half of the specified soil layer strip thickness, it is merged into the adjacent soil layer strip. If the remaining part is not less than half of the specified soil layer strip thickness, its actual thickness is used as a soil layer strip. The specified soil layer strip thickness is generally 0.5m.

[0055] S103, determine the depth from the top of the foundation pit to the center of each soil strip , where j = 1, 2, ..., The schematic diagram of the foundation pit divided into soil strips according to the specified excavation conditions is as follows: Figure 2 As shown, Figure 2 Where H is the distance from the top of the foundation pit to the bottom of the foundation pit, and h is the depth of the foundation pit under the specified excavation condition, that is, the distance from the top of the foundation pit to the bottom of the working pit.

[0056] S104, calculating the horizontal reaction coefficient of each soil strip according to the first preset formula , where the first preset formula is , where The horizontal reaction coefficient of the jth soil strip, which represents the i-th type soil layer, is Characterized as the proportional coefficient of the i-th type soil layer (MN / m 4 ), The center depth of the jth soil strip, which represents the i-th type soil layer, It is represented by the depth of the foundation pit under excavation conditions (m), Characterized as the internal friction angle of the i-th type soil layer, (°), Characterized by the cohesion of type i soil layer (kPa), It is characterized by the horizontal displacement of the retaining member at the bottom of the working pit (mm);

[0057] S105, calculating the horizontal displacement of each soil strip according to the second preset formula , where the second preset formula is , where The horizontal displacement of the jth soil strip in the i-th soil layer is represented by Characterized by the weight of the i-th type soil layer, Characterized as the active earth pressure coefficient of the i-th type soil layer, The upper depth of the jth soil strip, which represents the i-th type soil layer, The active earth pressure coefficient of the i-th soil layer is represented by the lower depth of the j-th soil layer strip. It is calculated by the following formula: .

[0058] Therefore, the elastic fulcrum method theory is adopted, which is more in line with the actual change law of displacement of foundation pit supported by natural slope and soil nail wall, realizes the calculation of horizontal displacement of each soil strip, and can provide effective support for deformation early warning in foundation pit engineering design.

[0059] Furthermore, the method for estimating foundation pit displacement in natural slope and soil nail wall support also includes the following steps:

[0060] The horizontal displacement of each type of soil layer is calculated by summing up the horizontal displacement of the soil strips corresponding to each type of soil layer. .

[0061] Thus, the calculation of horizontal displacement of each type of soil layer is realized, which further enables dynamic monitoring of displacement and deformation of the foundation pit during the entire implementation process, and further provides effective support for deformation early warning, which is conducive to avoiding unnecessary engineering waste and the occurrence of safety accidents.

[0062] Furthermore, the method for estimating the displacement of foundation pit in natural slope and soil nail wall support also includes the following steps: determining the slope angle of each type of soil layer according to the specified excavation conditions , soil active failure rupture angle ,in, ;

[0063] According to the slope angle , soil active failure rupture angle , according to the fifth preset formula, calculate the horizontal displacement adjustment coefficient for each type of soil layer , where the fifth preset formula is:

[0064] ;

[0065] in, It is represented by the graphic area formed by the slope surface and the vertical surface in the i-th type soil layer. It is represented by the graphical area formed by the active fracture surface and the vertical surface in the i-th type soil layer.

[0066] According to the horizontal displacement adjustment coefficient of each type of soil layer, the horizontal displacement of each type of soil layer is adjusted and optimized respectively.

[0067] Thus, the influence of soil layer parameters, slope gradient and other factors are comprehensively considered, and the accuracy of horizontal displacement estimation for each type of soil layer is further improved.

[0068] Furthermore, the method for estimating the displacement of the foundation pit in the natural slope and soil nail wall support also includes the following steps: according to the horizontal displacement of each soil strip According to the third preset formula, calculate the maximum horizontal displacement of the foundation pit slope top under the specified excavation condition , where the third preset formula is .

[0069] Thus, the maximum horizontal displacement of the top of the foundation pit slope under the specified excavation conditions can be estimated, which is conducive to the early warning of the overall displacement deformation and timely remedial measures in the foundation pit design.

[0070] Furthermore, the method for estimating the displacement of the foundation pit in the natural slope and soil nail wall support also includes the following steps: according to the maximum horizontal displacement of the top of the foundation pit under the specified excavation condition According to the principle that the soil volume within the horizontal and vertical deformation ranges is equal, the vertical displacement at a certain point k outside the foundation pit is determined according to the fourth preset formula. , where it is assumed that the vertical displacement of the foundation pit is distributed in a triangular shape from the inside to the outside of the foundation pit. The fourth preset formula is , It is represented by the horizontal distance from a certain k point outside the foundation pit to the edge of the foundation pit.

[0071] Thus, the vertical displacement of the foundation pit can be estimated, which is conducive to the comprehensive consideration of the displacement of the foundation pit.

[0072] Furthermore, the method for estimating foundation pit displacement in natural slope and soil nail wall support also includes the following steps:

[0073] Calculate the maximum vertical displacement of the foundation pit slope top under specified excavation conditions ,in, .

[0074] Therefore, the vertical displacement of the foundation pit is distributed in a triangular shape from the inside to the outside of the foundation pit, and is the largest near the top of the foundation pit slope, which enables the estimation of the maximum vertical displacement of the top of the foundation pit slope.

[0075] Furthermore, the method for estimating foundation pit displacement in natural slope and soil nail wall support also includes the following steps:

[0076] Determine the slope angle according to the specified excavation conditions , Active failure rupture angle of each type of soil layer ,in, ;

[0077] According to the slope angle , Active failure rupture angle of each type of soil layer , according to the sixth preset formula, calculate the horizontal and vertical displacement adjustment coefficients , where the sixth preset formula is:

[0078] ;

[0079] in, It is represented by the triangular area formed by the slope surface and the vertical surface in the entire foundation pit. It is represented by the polygonal area formed by the connecting line of active fracture surfaces of each soil layer in the entire foundation pit and the vertical surface.

[0080] According to the horizontal and vertical displacement adjustment coefficients, the maximum horizontal displacement of the foundation pit slope top and the maximum vertical displacement of the foundation pit slope top are adjusted and optimized respectively.

[0081] The principle of foundation pit displacement adjustment is as follows Figure 3 and Figure 4 As shown, taking m=3 as an example.

[0082]

[0083] Therefore, the maximum horizontal displacement and the maximum vertical displacement of the top of the foundation pit slope were adjusted and optimized by comprehensively considering the influence of soil parameters, slope gradient and other factors, which further improved the estimation accuracy and formed a unified setting standard, which can effectively avoid different design units and different formation conditions and propose different early warning displacement shortcomings.

[0084] According to an embodiment of the present invention, a system for estimating foundation pit displacement in natural slope and soil nail wall support is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for estimating foundation pit displacement in natural slope and soil nail wall support are implemented.

[0085] The following project overview is used to specifically verify and illustrate the method for estimating foundation pit displacement in natural slope and soil nail wall support proposed in the present invention.

[0086] Project Overview: A foundation pit is about 300m long and 70m wide, with a depth of 5-8m. Soil nail wall support is adopted, and the safety level of the foundation pit is level 2. There is no pile load within 2m of the excavation edge of the foundation pit. The planned excavation depth is designed according to a uniform load of 20kPa from 2m beyond the foundation pit to one times the excavation depth of the foundation pit. The foundation pit support structure is divided into 3 support sections. Among them:

[0087] Section 1-1: digging depth of about 5m, slope of 1:0.5, 3 soil nails, soil nail length of 6.0m, drilling diameter of 130mm, inclination of 15º, rod material 1C22 steel bar, one-time pressure grouting process, such as Figure 5 As shown, Figure 5 TD1, TD2, and TD3 are the soil nail numbers, 1C22 is a steel bar with a diameter of 22 mm, and l=6.0m@1500mm means that the soil nail length is 6m and the horizontal spacing is 1500mm.

[0088] Section 2-2: The excavation depth is about 6.5m, the slope is set at 1:0.5, 4 soil nails are set, the soil nail length is 9.0m, the drilling diameter is 130mm, the inclination angle is 15º, the rod material is 1C22 steel bar, and the one-time pressure grouting process is adopted. Figure 6 As shown, Figure 6 TD1, TD2, TD3, and TD4 are the soil nail numbers. 1C22 is a steel bar with a diameter of 22 mm. l=9.0m@1500mm means that the length of the soil nail is 9 m and the horizontal spacing is 1500 mm.

[0089] Section 3-3: The excavation depth is about 8m, the slope is set at 1:0.5, 5 soil nails are set, the soil nail length is 9.0m, the drilling diameter is 130mm, the inclination angle is 15º, the rod material is 1C22 steel bar, and the one-time pressure grouting process is adopted. Figure 7 As shown, Figure 7 TD1, TD2, TD3, TD4, and TD5 are the soil nail numbers. 1C22 is a steel bar with a diameter of 22 mm. l=9.0m@1500mm means that the length of the soil nail is 9m and the horizontal spacing is 1500mm.

[0090] Engineering geological conditions: The soil types within the excavation depth of the foundation pit can be divided into three layers, which are described from top to bottom as follows:

[0091] ① Miscellaneous fill (Q4 ml )

[0092] It is mottled, loose, slightly wet, and mainly composed of clay and construction waste, with a small amount of domestic waste. It is widely distributed in the site, with a thickness of 0.4 to 9.20 m and an average of 2.95 m.

[0093] ②Silty soil (Q4 al+pl )

[0094] Grayish yellow, medium dense, wet, uniform soil, general shaking reaction, containing iron and manganese oxides, with thin layers of silty clay and medium-coarse sand in some places. This layer is widely distributed in the site, with a thickness of 0.90 to 8.70 m, with an average of 3.73 m.

[0095] ③Silty clay (Q4 al+pl ) Yellowish brown, plastic, rubbed into strips by hand, containing iron and manganese oxides and nodules, with sporadic ginger stones visible, slightly smooth cut surface, medium dry strength and toughness, uneven soil, locally containing silt masses and thin layers. This layer is widely distributed in the site, with a thickness of 0.50 to 9.40 m, an average of 5.00 m.

[0096] The relevant mechanical parameters of the above soil types are shown in Table 1.

[0097] Table 1 Relevant mechanical parameters of different types of soil layers

[0098]

[0099] The hydrogeological unit of the survey area is located in the sand and gravel water-rich area at the front edge of the alluvial fan. The groundwater type is Quaternary pore water. It is mainly replenished by atmospheric precipitation, surface water seepage and upstream river seepage. The water level was buried at a depth of 3.0 to 5.0 m during the survey.

[0100] The displacement estimation method of foundation pit in natural slope and soil nail wall support proposed by the present invention is used to estimate the displacement of foundation pit sections 1-1, 2-2 and 3-3 respectively, as follows:

[0101] For section 1-1, the depth of the foundation pit is h, which is 5.0m. From top to bottom, the soil types are: ① miscellaneous fill, with a height of h1 of 2.95m, divided into 6 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.5m, 0.45m from bottom to top; ② silt, with a height of h2 of 2.05m, divided into 4 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.55m from bottom to top; the horizontal displacement of the retaining member at the bottom of the working pit is 10mm.

[0102] For section 2-2, the depth of the foundation pit is h is 6.5m. From top to bottom, the soil types are: ① miscellaneous fill, with a height h1 of 2.95m, divided into 6 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.5m, 0.45m from bottom to top; ② silt, with a height h2 of 3.55m, divided into 7 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.5m, 0.5m, 0.5m, 0.55m from bottom to top; the horizontal displacement of the retaining member at the bottom of the working pit is 10mm.

[0103] For section 3-3, the depth h of the foundation pit is 8.0m. From top to bottom, the soil types are: ① miscellaneous fill, with a height h1 of 2.95m, divided into 6 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.5m, 0.45m from bottom to top; ② silt, with a height h2 of 3.73m, divided into 7 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.5m, 0.5m, 0.5m, 0.73m from bottom to top; ③ silty clay, with a height h3 of 1.32m, divided into 3 soil strips, and the thickness of the soil strips are 0.5m, 0.5m, 0.32m from bottom to top; the horizontal displacement of the retaining member at the bottom of the working pit is 10mm.

[0104] The estimated results of foundation pit displacement are shown in Tables 2 and 3.

[0105] Table 2 Calculation results of displacement adjustment coefficient

[0106]

[0107] Table 3 Estimation results of maximum horizontal and vertical displacements of foundation pit slope top

[0108]

[0109] Before the excavation of the foundation pit, the third-party monitoring unit monitored the horizontal and vertical displacement of the top of the foundation pit until the fertilizer tank of the foundation pit was backfilled. The statistical analysis of the foundation pit monitoring data showed that the maximum horizontal and vertical displacement of the top of the foundation pit slope is shown in Table 4.

[0110] Table 4 Monitoring results of maximum horizontal and vertical displacements of foundation pit slope top

[0111]

[0112] It can be seen from Tables 2 to 4 that the estimated results obtained by the method for estimating the displacement of the foundation pit in the natural slope and soil nail wall support proposed by the present invention are not much different from the monitoring results, at about 10%, which is within a reasonable range. This is due to the long construction period of the foundation pit, and the normal deviation caused by factors such as edge load, precipitation, and earth excavation during the construction process. It can be seen that the method and system for estimating the displacement of the foundation pit in the natural slope and soil nail wall support proposed by the present invention are more in line with the actual displacement change law of the foundation pit in the natural slope and soil nail wall support type, and can effectively make up for the deficiency of the current specifications in not having a unified standard and principle for displacement warning.

[0113] The steps in the method of the present invention can be adjusted in order, combined or deleted according to actual needs.

[0114] The units in the device of the present invention can be combined, divided and deleted according to actual needs.

[0115] A person skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable programmable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for estimating foundation pit displacement in natural slope and soil nail wall support, characterized in that: The following steps are involved: Determine the foundation pit depth according to the specified excavation conditions , thickness of different types of soil layers , horizontal displacement of retaining elements at the bottom of the working pit ,in, , i=1,2,…,m; The soil layers of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit are divided into different types of soil layers, and each type of soil layer forms Soil layer strips, among which, ≥1; Determine the depth from the top of the foundation pit to the center of each soil strip , where j = 1, 2, ..., ; According to the first preset formula, calculate the horizontal reaction coefficient of each soil strip , where the first preset formula is , where The horizontal reaction coefficient of the jth soil strip, which represents the i-th type soil layer, is Characterized as the proportional coefficient of the i-th type soil layer (MN / m 4 ), The center depth of the jth soil strip, which represents the i-th type soil layer, It is represented by the depth of the foundation pit under excavation conditions (m), Characterized as the internal friction angle of the i-th type soil layer, (°), Characterized by the cohesion of type i soil layer (kPa), It is characterized by the horizontal displacement of the retaining member at the bottom of the working pit (mm); According to the second preset formula, the horizontal displacement of each soil strip is calculated. , where the second preset formula is , where The horizontal displacement of the jth soil strip of the i-th soil layer is represented by Characterized by the weight of the i-th type soil layer, Characterized as the active earth pressure coefficient of the i-th type soil layer, The upper depth of the jth soil strip, which represents the i-th type soil layer, The lower depth of the jth soil strip characterized by the i-th type soil layer.

2. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 1 is characterized in that: When the soil layer of the foundation pit slope from the top of the foundation pit to the depth of the foundation pit is stratified according to different types of soil layers, each type of soil layer is stratified according to the specified soil layer strip thickness. If the remaining part is less than half of the specified soil layer strip thickness, it is merged into the adjacent soil layer strip. If the remaining part is not less than half of the specified soil layer strip thickness, its actual thickness is used as a soil layer strip.

3. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 1 is characterized in that: Active earth pressure coefficient of type i soil layer It is calculated by the following formula: .

4. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to any one of claims 1 to 3, characterized in that: The following steps are also included: The horizontal displacement of each type of soil layer is calculated by summing up the horizontal displacement of the soil strips corresponding to each type of soil layer. .

5. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 4 is characterized in that: The following steps are also included: According to the horizontal displacement of each soil strip According to the third preset formula, calculate the maximum horizontal displacement of the foundation pit slope top under the specified excavation condition , where the third preset formula is .

6. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 5 is characterized in that: The following steps are also included: According to the maximum horizontal displacement of the foundation pit slope top under the specified excavation conditions According to the principle that the soil volume within the horizontal and vertical deformation ranges is equal, the vertical displacement at a certain point k outside the foundation pit is determined according to the fourth preset formula. , where it is assumed that the vertical displacement of the foundation pit is distributed in a triangular shape from the inside to the outside of the foundation pit. The fourth preset formula is , It is represented by the horizontal distance from a certain k point outside the foundation pit to the edge of the foundation pit.

7. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 6 is characterized in that: The following steps are also included: Calculate the maximum vertical displacement of the foundation pit slope top under specified excavation conditions ,in, .

8. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 4 is characterized in that: The following steps are also included: Determine the slope angle for each type of soil layer according to the specified excavation conditions , soil active failure rupture angle ,in, ; According to the slope angle , soil active failure rupture angle , according to the fifth preset formula, calculate the horizontal displacement adjustment coefficient for each type of soil layer , where the fifth preset formula is: ； in, It is represented by the graphic area formed by the slope surface and the vertical surface in the i-th type soil layer. It is represented by the graphical area formed by the active fracture surface and the vertical surface in the i-th type soil layer. According to the horizontal displacement adjustment coefficient of each type of soil layer, the horizontal displacement of each type of soil layer is adjusted and optimized respectively.

9. The method for estimating foundation pit displacement in natural slope and soil nail wall support according to claim 7 is characterized in that: The following steps are also included: Determine the slope angle according to the specified excavation conditions , Active failure rupture angle of each type of soil layer ,in, ; According to the slope angle , Active failure rupture angle of each type of soil layer , according to the sixth preset formula, calculate the horizontal and vertical displacement adjustment coefficients , where the sixth preset formula is: ； in, It is represented by the triangular area formed by the slope surface and the vertical surface in the entire foundation pit. It is represented by the polygonal area formed by the connecting line of active fracture surfaces of each soil layer in the entire foundation pit and the vertical surface. According to the horizontal and vertical displacement adjustment coefficients, the maximum horizontal displacement of the foundation pit slope top and the maximum vertical displacement of the foundation pit slope top are adjusted and optimized respectively.

10. A foundation pit displacement estimation system in natural slope and soil nail wall support, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method for estimating foundation pit displacement in natural slope reduction and soil nail wall support described in any one of claims 1 to 9 are implemented.

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