Method and system for evaluating construction safety of pile foundation of newly-built building along subway

Abstract

The invention provides a construction safety assessment method and system for a new building pile foundation along a subway in a soft soil area, and the method comprises the steps: building a numerical model of a pile foundation adjacent to an operating subway and a surrounding soil body, and obtaining the distribution of a stress field around the pile foundation; through data collection and equation fitting, a relation model of the dynamic shear modulus and the dynamic shear strain of the soil body around the pile foundation and the mechanical property parameters of the soil body of the soft soil is obtained; according to the relation model, a relation model between the soft soil dynamic stress and the static strength reduction rate is constructed; according to the relation model between the soft soil dynamic stress and the static strength reduction rate, a pile side resistance experience composition formula is combined, the pile foundation bearing capacity obtained after reduction is calculated, then the loss ratio of the pile foundation bearing capacity obtained after reduction is calculated, and therefore the construction safety rating of the newly-built building pile foundation along the subway is evaluated. According to the method, regular summary of the bearing capacity loss of the pile foundation in the soft soil area is achieved, and effective guidance and an optimized path are provided for planning and construction of newly-built buildings along subways in the soft soil area.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering structure analysis and safety assessment, and in particular to a method and system for assessing the safety of pile foundation construction of new buildings along subway lines in soft soil areas, as well as a corresponding computer assessment device and a computer-readable storage medium. Background Art

[0002] In the context of rapid urban development, areas along subway lines are often selected as ideal locations for new buildings. However, the vibration and dynamic loads generated by subway operations will affect the pile foundations and surrounding soil of adjacent new buildings, which may reduce the stability of the pile foundations and thus affect the safety of the buildings. Therefore, before the pile foundation construction of new buildings along the subway line, a construction safety assessment must be conducted to ensure that the mutual impact between the new buildings and the subway system will not cause structural safety problems.

[0003] After searching, we found:

[0004] The Chinese invention patent application with publication number CN202410047524.X, "A safety risk assessment method for complex foundation pit construction adjacent to an existing subway", establishes a three-dimensional calculation model, simulates the foundation pit excavation process, obtains the simulated deformation data of the existing subway, determines the risk points where the foundation pit project affects the existing subway, obtains the proportion of the simulated deformation value of the risk point, determines the risk assessment level of each risk point, and obtains the safety risk assessment results of the complex foundation pit construction. This method mainly simulates and evaluates the risks of foundation pit construction, and does not consider the settlement and stress distribution of pile foundations that are continuously affected by the existing subway after the construction is completed; the applicability of this method in soft soil areas has certain limitations. Due to the large deformation and low permeability of the soil in soft soil areas, there are unique mechanical properties, such as creep effect, hysteresis deformation and water-soil interaction of the soil, which affects the accuracy of safety assessment in soft soil areas. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and system for evaluating the safety of pile foundation construction of new buildings along subway lines in soft soil areas based on dynamic stress field simulation along subway lines, as well as data analysis and equation fitting technology, and also provides a corresponding computer evaluation device and computer-readable storage medium.

[0006] According to one aspect of the present invention, a method for evaluating the safety of pile foundation construction of new buildings along a subway line is provided, comprising:

[0007] A numerical model of the pile foundation and the surrounding soil near the operating subway was established to obtain the stress field distribution around the pile foundation;

[0008] Based on the stress field distribution around the pile foundation, a relationship model between the dynamic shear modulus and dynamic shear strain of the soil around the pile foundation and the mechanical property parameters of the soft soil is obtained;

[0009] According to the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, a relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed;

[0010] According to the relationship model between the dynamic stress of soft soil and the static strength reduction rate, combined with the empirical formula of pile side resistance, the reduced pile foundation bearing capacity is calculated;

[0011] Based on the reduced pile foundation bearing capacity, the reduced pile foundation bearing capacity loss ratio is calculated to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

[0012] Preferably, the step of establishing a numerical model of a pile foundation and its surrounding soil adjacent to an operating subway to obtain a stress field distribution around the pile foundation includes:

[0013] According to the obtained subway data in the area to be tested, the running speed v of the subway in the area to be tested, the length L of the pile foundation of the new building in the area to be tested, and the distance D between the planned construction location of the pile foundation of the new building and the subway are determined, and a numerical model of the pile foundation and the surrounding soil of the subway in the area to be analyzed is established;

[0014] The dynamic load caused by subway operation is applied to the numerical model to calculate the dynamic stress field distribution of the surrounding soil and pile foundation caused by the dynamic load of the subway train, and the stress field distribution of the soil around the pile foundation adjacent to the operating subway is obtained, where:

[0015] The stress field distribution includes: the confining pressure σ borne by the surrounding soil and pile foundation p =γ′h·K0 and the dynamic stress σ borne by the surrounding soil and pile foundation d , where γ′h is the soil pressure at depth h, γ′ is the effective weight of the soil, and K0 is the static earth pressure coefficient.

[0016] Preferably, the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation obtained based on the stress field distribution around the pile foundation includes:

[0017] Based on the stress field distribution around the pile foundation, the dynamic stress ratio CSR = σ d / σ p , where σ d is the dynamic stress on the surrounding soil and pile foundation, σ p The confining pressure borne by the surrounding soil and pile foundation;

[0018] Establish the dynamic shear modulus G of saturated soft soil under different conditionsd and undrained strength S u The ratio of dynamic shear strain γ d The relationship model between Among them, G d is the dynamic shear modulus of soft soil, S u is the undrained shear strength of soft soil, γ d is the dynamic shear strain, p1 and k1 are fitting parameters;

[0019] The softening coefficient δ is defined as the dynamic shear modulus G obtained under the Nth vibration cycle condition. dN The dynamic shear modulus G obtained under the first vibration cycle condition d1 ratio; establish dynamic stress ratio CSR = σ d / σ p and softening coefficient δ = G dN / G d1 The relationship between is δ=f(CSR)=p2·CSR+k2, where p2 and k2 are fitting parameters;

[0020] Establish soil dynamic shear strain γ d The relationship between the dynamic stress ratio CSR is: Among them, C and D are fitting parameters.

[0021] Preferably, according to the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, a relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed, including:

[0022] According to the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of soft soil around the pile foundation, including the dynamic shear modulus of saturated soft soil G d and undrained strength S u The ratio of dynamic shear strain γ d The relationship model between The relationship between the dynamic stress ratio CSR and the softening coefficient δ is δ = f(CSR), and the relationship between the soil dynamic shear strain γd and the dynamic stress ratio CSR is γ d =f(CSR), and the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of soft soil around the pile foundation and the static strength reduction rate is obtained. Among them, S u0 and G d0 For γ d is infinite, that is, γ d =γ d0 Time u and G d The value of G d0 For γ d =γ d0 The dynamic shear modulus, Su0 For γ d =γ d0 Undrained shear strength, γ d0 is an infinitesimal quantity, γ da is the dynamic shear strain of the soil at position a under dynamic stress, G da For γ d =γ da The dynamic shear modulus, S ua For γ d =γ da Undrained shear strength;

[0023] Based on the stress field distribution around the pile foundation, substitute the relationship model δ=f(CSR),γ d =f(CSR), the relationship between the dynamic stress of soft soil and the static strength reduction rate can be finally obtained, that is, Relationship between S and dynamic stress ratio CSR ua , S u0 The relationship with CSR is:

[0024]

[0025] Preferably, the reduced pile foundation bearing capacity is calculated based on the relationship model between the soft soil dynamic stress and the static strength reduction rate, combined with the strength reduction rate of the pile foundation side bearing capacity under static conditions, and includes:

[0026] Define the strength reduction rate of pile side bearing capacity under static force as λ, then Q sk ′=λ·Q sk ; Among them, Q sk is the pile side bearing capacity without considering dynamic load, Q sk ' is the pile side bearing capacity after dynamic load and reduction, The relationship model between dynamic stress and static strength reduction rate of soft soil get

[0027] The reduced single pile vertical ultimate bearing capacity Q is obtained by using the general pile foundation single pile vertical ultimate bearing capacity formula and the regional pile foundation bearing capacity empirical formula. uk ′; the calculation formula for the vertical ultimate bearing capacity of a single pile of a general pile foundation is Q uk =Q sk +Q pk , Q sk is the pile side bearing capacity, Q pk is the ultimate end bearing capacity of the pile foundation. The empirical formula for the bearing capacity of the pile foundation in the region is a summary of the existing prior knowledge in each region. It can be obtained that Q pk =q·Qsk , where q is an empirical parameter; considering the strength reduction, the reduced pile side bearing capacity Q sk ′=λ·Q sk , the reduced vertical ultimate bearing capacity of a single pile can be calculated as Q uk =Q′ sk +q·Q sk =λ·Q sk +q·Q sk =(λ+q)Q sk .

[0028] Preferably, the calculating, according to the reduced pile foundation bearing capacity, to obtain the reduced pile foundation bearing capacity loss ratio comprises:

[0029] Based on the reduced vertical ultimate bearing capacity of a single pile Q uk ′ and the vertical ultimate bearing capacity of a single pile without considering dynamic load Q uk , the loss ratio of single pile bearing capacity caused by dynamic load is calculated as:

[0030] Based on the single pile bearing capacity loss ratio, the safety of pile foundation construction of new buildings along the subway line is evaluated:

[0031]

[0032] Among them, m is the set warning threshold.

[0033] According to another aspect of the present invention, a system for evaluating the safety of pile foundation construction of new buildings along a subway line is provided, comprising:

[0034] Dynamic stress field construction module, which is used to establish a numerical model of the pile foundation and the surrounding soil near the operating subway, and obtain the stress field distribution around the pile foundation;

[0035] A soft soil parameter relationship construction module, which obtains a relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soft soil body borne by the soil body around the pile foundation based on the dynamic stress field around the pile foundation; and constructs a relationship model between the dynamic stress of the soft soil and the static strength reduction rate according to the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soft soil body borne by the soil body around the pile foundation;

[0036] A pile foundation bearing capacity calculation module, which is used to calculate the reduced pile foundation bearing capacity based on the relationship model between the soft soil dynamic stress and the static strength reduction rate and the empirical formula of the pile side resistance;

[0037] The pile foundation bearing capacity loss calculation module is used to calculate the reduced pile foundation bearing capacity loss ratio according to the reduced pile foundation bearing capacity, so as to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

[0038] According to a third aspect of the present invention, there is provided a computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, can be used to execute any one of the methods described above in the present invention, or to run the system described above in the present invention.

[0039] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, can be used to execute any of the methods described above in the present invention, or to run the system described above in the present invention.

[0040] Due to the adoption of the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0041] The method and system for assessing the safety of pile foundation construction of new buildings along subway lines provided by the present invention fully consider the poor engineering properties of soft soil by simulating the dynamic stress field of the existing subway operation, combining equation fitting and data analysis, and then quickly providing a scientific basis for the safety assessment of pile foundations of new buildings around the subway through equation fitting, thus avoiding tedious calculations.

[0042] The method and system for assessing the safety of pile foundation construction of new buildings along subway lines provided by the present invention simulate the dynamic impact of subway operation on surrounding soil and pile foundations, specifically consider the soil characteristics of soft soil areas, and better assess the long-term safety of pile foundations of new buildings in soft soil areas along subway lines, thereby providing an effective reference for the overall planning and risk control along subway lines and ensuring the safety of subway operation and surrounding buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0044] Figure 1 The present invention is a flowchart of a method for evaluating the safety of pile foundation construction of new buildings along a subway line in one embodiment of the present invention.

[0045] Figure 2 The present invention is a flowchart of a method for assessing the safety of pile foundation construction of new buildings along subway lines in a preferred embodiment of the present invention.

[0046] Figure 3Schematic diagram of numerical simulation results and equation fitting results in a preferred embodiment of the present invention; wherein, (a) is the relationship between the dynamic stress around the pile foundation and the planned construction position of the new building pile foundation and the distance D from the subway, (b) is the relationship between the dynamic stress around the pile foundation and the length L of the new building pile foundation in the test area, and (c) is the relationship between the dynamic stress around the pile foundation and the subway speed v in the test area.

[0047] Figure 4 It is a schematic diagram of the fitting results of the relationship between the ratio of the dynamic shear modulus to the undrained strength and the dynamic shear strain in a preferred embodiment of the present invention.

[0048] Figure 5 Schematic diagram of the relationship between soil dynamic stress ratio CSR and softening coefficient δ in a preferred embodiment of the present invention.

[0049] Figure 6 is the soil dynamic shear strain γ in a preferred embodiment of the present invention d Schematic diagram of the relationship between and softening coefficient δ.

[0050] Figure 7 The present invention is a schematic diagram of the components of a system for assessing the safety of pile foundation construction of new buildings along subway lines in one embodiment of the present invention. DETAILED DESCRIPTION

[0051] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0052] The existing foundation pit construction safety risk assessment technology has certain limitations in its applicability in soft soil areas. Soft soil areas have unique mechanical properties due to large soil deformation and low permeability, and the accuracy of this technology when applied to safety assessment in soft soil areas is also affected. In one embodiment of the present invention, a safety assessment method for pile foundation construction of new buildings along subway lines in soft soil areas is provided to address the safety issues that need to be considered before the construction of new buildings along subway lines in soft soil areas. The method establishes the dynamic stress field generated by subway operation through numerical simulation, comprehensively analyzes the relationship between the confining pressure of the pile foundation of the new building, the mechanical response of the soft soil body, and the dynamic stress field of subway operation, and conducts pile foundation bearing safety analysis and early warning. The method realizes the regularity summary of the loss of pile foundation bearing capacity in soft soil areas by collecting, sorting and fitting a large amount of soil data, and provides effective guidance and optimization path for the planning and construction of new buildings along subway lines in soft soil areas.

[0053] Specifically, Figure 1 As shown, the method for evaluating the safety of pile foundation construction of new buildings along the subway line provided in this embodiment may include the following operations:

[0054] S100, establish a numerical model of the pile foundation and its surrounding soil near the operating subway, and obtain the stress field distribution around the pile foundation;

[0055] S200, based on the stress field distribution around the pile foundation, obtains the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation;

[0056] S300, based on the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, the relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed;

[0057] S400, based on the relationship model between the dynamic stress of soft soil and the static strength reduction rate, combined with the empirical formula of pile side resistance, the reduced pile foundation bearing capacity is calculated;

[0058] S500, based on the reduced pile foundation bearing capacity, calculates the reduced pile foundation bearing capacity loss ratio to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

[0059] The technical solution provided by the above embodiment of the present invention is further described in detail below in combination with preferred implementation modes, specific application examples and drawings.

[0060] like Figure 2 As shown, in some preferred implementation manners, the method for safety assessment of pile foundation construction of new buildings along subway lines provided by the above embodiments of the present invention may further include the following operations:

[0061] S1, pre-collect the subway-related data in the area to be tested, determine the subway speed v in the area to be tested, the length of the pile foundation of the new building in the area to be tested L, and the distance D between the planned construction location of the pile foundation of the new building and the subway, establish a numerical model of the pile foundation and the surrounding soil of the subway in the area to be analyzed, and apply the dynamic load caused by the subway operation to the model based on the finite element method. According to different v, L, and D parameters, adjust the parameters of the numerical model, and calculate the dynamic stress field results respectively. By calculating the dynamic stress field distribution generated by the dynamic load of the subway train on the surrounding soil and pile foundation, the stress field distribution of the pile foundation of the subway in operation and the soil around the pile foundation is solved, and the effective confining pressure σ borne by the pile foundation is obtained. p and dynamic stress σ d . Further:

[0062] The stress field distribution includes: the confining pressure σ borne by the surrounding soil and pile foundation p =γ′h·K0 and the dynamic stress σ borne by the surrounding soil and pile foundation d, where γ′h is the soil pressure at depth h, γ′ is the effective weight of the soil, and K0 is the static earth pressure coefficient. Both the confining pressure and the dynamic stress can be obtained from the numerical model. The confining pressure can be obtained by the given calculation formula after the numerical model is established; the dynamic stress is calculated by the numerical model after applying the dynamic load.

[0063] In some preferred implementations, the above S1, pre-collecting subway-related data in the area to be tested, includes:

[0064] Obtain data such as the ground conditions in the area along the subway line, subway operation parameters, design drawings of the proposed new buildings, and engineering planning parameters, and determine the running speed v of the subway in the area to be tested, the length L of the pile foundation of the new building in the area to be tested, and the distance D between the planned construction location of the pile foundation of the new building and the subway; where:

[0065] The running speed v of the subway in the test area is determined according to the subway operation parameters;

[0066] The length L of the pile foundation of the new building in the area to be tested is determined according to the design drawings of the proposed new building and the engineering planning parameters;

[0067] The distance d between the planned construction location of the new building pile foundation and the subway is calculated based on the coordinates in the field measurement or the design drawings of the proposed new building, as well as the ground conditions in the area along the subway line. Among them, the distance D between the new building pile foundation and the subway is the horizontal distance between the subway line.

[0068] In a specific application example, taking a point 10m below the ground surface along the Shanghai subway line as an example, according to the soil survey report and indoor test results, the average effective weight of the soft soil layer is 10kN / m 3 , the static side pressure coefficient K0 coefficient is 0.62.

[0069] The confining pressure at this depth is calculated as: p =γ′h·K0=10·10·0.62=62kPa; numerical calculation of the dynamic stress σ at this depth d 0.8 kPa. Among them, γ′h is the soil pressure at a depth of h = 10m, γ′ is the effective weight of the soil, and K0 is the static earth pressure coefficient.

[0070] The numerical simulation results and equation fitting results are shown in Figure 3 As shown in (a) to (c).

[0071] S2, the mechanical properties of the soil in the soft soil area include: shear strength, elastic modulus, shear modulus, undrained strength, dynamic shear strain, etc., which are inherent properties of the soil and are determined through experiments. The relationship between the dynamic stress of soft clay and the percentage of static strength reduction is established. Through data collection and equation fitting, the dynamic shear modulus G of saturated clay under different conditions is obtained.d and undrained strength S u The ratio of dynamic shear strain γ d Relationship

[0072] Based on the stress field distribution around the pile foundation, the dynamic stress ratio CSR = σ d / σ p , where σ d is the dynamic stress on the surrounding soil and pile foundation, σ p The confining pressure borne by the surrounding soil and pile foundation;

[0073] Based on the stress field distribution around the pile foundation, the dynamic shear modulus G is obtained. d and undrained strength S u The ratio of dynamic shear strain γ d The relationship is as Figure 4 As shown in the figure, it can be seen that the dynamic shear modulus G d and undrained strength S u The ratio of dynamic shear strain γ d There is a good relationship between them. Dynamic shear modulus G of saturated soft soil under different conditions d and undrained strength S u The ratio of dynamic shear strain γ d The relationship model between Among them, G d is the dynamic shear modulus of soft soil, S u is the undrained shear strength of soft soil, γ d is the dynamic shear strain, p1 and k1 are fitting parameters.

[0074] In a specific application example, according to From the fitting results, we can see that p1=85.04,k1=20.941,G d is the dynamic shear modulus of soft soil, S u is the undrained shear strength of soft soil, γ d is the dynamic shear strain, p1 and k1 are fitting parameters.

[0075] S3, introduce the softening coefficient δ, which is defined as the dynamic shear modulus G obtained under the Nth vibration cycle condition. dN The dynamic shear modulus G under the first vibration cycle condition d1 The ratio of the soil dynamic stress ratio CSR (CSR = σ d / σ p ) and softening coefficient δ(δ=G dN / G d1) and fitting to obtain the relationship δ=f(CSR)=p2·CSR+k2, where p2 and k2 are fitting parameters.

[0076] In a specific application example, taking Shanghai as an example, according to the results of soil mechanical properties research, the relationship between soil dynamic stress ratio CSR and softening coefficient δ is obtained as follows: Figure 5 As shown, according to the fitting results, we can get:

[0077]

[0078] S4, through data statistical analysis and equation fitting method, the soil dynamic shear strain γ is obtained d The relationship between the dynamic stress ratio CSR and the fitting equation is Among them, C and D are fitting parameters.

[0079] In a specific application example, taking Shanghai as an example, according to the results of soil mechanical properties research, the soil dynamic shear strain γ d The relationship between the dynamic stress ratio CSR is as follows Figure 6 As shown, according to the fitting results, we can get:

[0080]

[0081] Among them, C and D are fitting parameters.

[0082] Through S2 to S4, the above S200 is completed, and the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of soft soil borne by the pile foundation is obtained through data collection and equation fitting.

[0083] S5, according to the relationship shown in S2~S4, the relationship between soil dynamic shear strain and soil dynamic stress ratio CSR and softening coefficient δ is obtained d =f(CSR)=f(δ), combined with the relationship shown in S2, the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical properties of soft soil around the pile foundation and the static strength reduction rate can be obtained. Among them, S u0 and G d0 For γ d is infinite, that is, γ d =γ d0 Time u and G d The value of G d0 For γ d =γ d0 The dynamic shear modulus, S u0 For γ d =γ d0 Undrained shear strength, γda is the dynamic shear strain of the soil at position a under dynamic stress, G da For γ d =γ da The dynamic shear modulus, S ua For γ d =γ da Undrained shear strength.

[0084] Based on the stress field distribution around the pile foundation, substitute the relationship model The relationship between the dynamic stress of soft soil and the static strength reduction rate can be finally obtained: Relationship between S and dynamic stress ratio CSR ua , S u0 The relationship with CSR is:

[0085]

[0086] In a specific application example, taking Shanghai as an example, according to the relationship between S2, S3, and S4, we can get:

[0087]

[0088] Among them, γ d0 is an infinitesimal quantity, we can let γ d0 =1E-5.

[0089] Through S5, the above S300 is completed, and the step of constructing a relationship model between the dynamic stress of soft soil and the static strength reduction rate is performed according to the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soft soil body borne by the pile foundation.

[0090] S6, due to the daily operation of the subway, there are dynamic loads in the area along the subway line, which will affect the bearing capacity Q of the pile foundation. sk The influence of the pile foundation side bearing capacity is reduced, and the strength reduction rate of the pile foundation side bearing capacity under static force is defined as λ, that is, Q sk ′=λ·Q sk , where Q sk is the pile side bearing capacity without considering dynamic load, Q sk ′ is the pile side bearing capacity after dynamic load and reduction, and the calculation formula is: From the relation in S5, we can get get

[0091] In a specific application example, taking Shanghai as an example, the relationship in S5 can be obtained:

[0092]

[0093] S7, through the general pile foundation single pile vertical ultimate bearing capacity formula and the regional pile foundation bearing capacity empirical formula, the reduced single pile vertical ultimate bearing capacity Q is obtained uk ′; the calculation formula for the vertical ultimate bearing capacity of a single pile of a general pile foundation is Q uk =Q sk +Q pk , Q sk is the pile side bearing capacity, Q pk is the ultimate end bearing capacity of the pile foundation. The empirical formula for the bearing capacity of regional pile foundations is a summary of the existing prior knowledge in various regions. Considering the strength reduction, the reduced pile side bearing capacity Q sk ′=λ·Q sk , the calculation formula of the reduced vertical ultimate bearing capacity of a single pile is Q uk =Q sk +q·Q sk =λ·Q sk +q·Q sk =(λ+q)Q sk .

[0094] In a specific application example, taking Shanghai as an example, the general Q sk Percentage vertical bearing capacity Q uk 80% of the contribution, or Q sk =80%×Q uk , we can get q = 0.25, then Q uk =Q sk +Q pk =Q sk +0.25Q sk ; Considering strength reduction, Q sk ′=λ·Q sk , the calculation formula for the reduced vertical ultimate bearing capacity of a single pile is Q′ uk =Q′ sk +0.25Q sk =λ·Q sk +0.25Q sk =(λ+0.25)Q sk .

[0095] Through S6 to S7, the above S400 is completed, and the step of calculating the reduced pile foundation bearing capacity is performed based on the relationship model between the dynamic stress of soft soil and the static strength reduction rate and the empirical formula of the pile side resistance.

[0096] S8, according to the Technical Specification for Building Pile Foundation (JGJ94-2008) and the Code for Design of Building Foundation (GB50007-2011), based on the reduced vertical ultimate bearing capacity of a single pile Q uk ′ and the vertical ultimate bearing capacity of a single pile without considering dynamic load Q uk, the loss ratio of single pile bearing capacity caused by dynamic load is calculated as: Based on the single pile bearing capacity loss wallpaper, the safety of pile foundation construction of new buildings along the subway line is rated, and the safety of the assessed pile foundation is determined:

[0097]

[0098] Among them, m is the set warning threshold.

[0099] In a specific application example, when the measured single pile bearing capacity loss exceeds a set percentage (e.g. 30%) of the average value, the cause needs to be analyzed. Specifically:

[0100] The reduced single pile vertical ultimate bearing capacity calculation formula Q′ in S7 is uk =Q′ sk +0.25Q sk =λ·Q sk +0.25Q sk =(λ+0.25)Q sk , then the bearing capacity loss of a single pile is:

[0101] Q uk When the loss is within a set percentage (e.g. 30%), monitoring can be strengthened;

[0102] Q uk If the loss exceeds the set percentage (e.g. 30%), there will be a danger alarm and it needs to be handled;

[0103] Right now The value range of , therefore:

[0104]

[0105] Through S8, the above S500 is completed, and the reduced pile foundation bearing capacity loss ratio is calculated according to the reduced pile foundation bearing capacity, so as to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

[0106] In the above-mentioned embodiment of the present invention, data statistical analysis is achieved by acquiring required data in the soft soil dynamic property file and performing statistical analysis.

[0107] Based on the same inventive concept, an embodiment of the present invention also provides a safety assessment system for pile foundation construction of new buildings along subway lines.

[0108] Specifically, Figure 7 As shown, the safety assessment system for pile foundation construction of new buildings along the subway provided in this embodiment may include the following modules:

[0109] Dynamic stress field construction module, which is used to establish a numerical model of the pile foundation and the surrounding soil near the operating subway, and obtain the stress field distribution around the pile foundation;

[0110] Soft soil parameter relationship construction module: This module is based on the dynamic stress field around the pile foundation. Through data collection and equation fitting, it obtains the relationship model between the dynamic shear modulus and dynamic shear strain of the soil around the pile foundation and the mechanical property parameters of the soft soil. According to the relationship model between the dynamic shear modulus and dynamic shear strain of the soil around the pile foundation and the mechanical property parameters of the soft soil, it constructs the relationship model between the dynamic stress of the soft soil and the static strength reduction rate.

[0111] Pile foundation bearing capacity calculation module, which is used to calculate the reduced pile foundation bearing capacity based on the relationship model between soft soil dynamic stress and static strength reduction rate, combined with the empirical formula of pile side resistance;

[0112] The pile foundation bearing capacity loss calculation module is used to calculate the reduced pile foundation bearing capacity loss ratio based on the reduced pile foundation bearing capacity, so as to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

[0113] The following further describes in detail the working contents of the pile foundation construction safety assessment system for new buildings along subway lines provided by this embodiment.

[0114] The work content of the dynamic stress field construction module includes:

[0115] The subway speed v in the area to be measured, the length L of the pile foundation of the new building in the area to be measured, and the distance D between the planned construction location of the pile foundation of the new building and the subway are known. A numerical model of the pile foundation and the surrounding soil near the operating subway in the area to be analyzed is established. The dynamic load caused by the operation of the subway is applied to the model based on the finite element method. The dynamic stress field distribution of the dynamic load of the subway train on the surrounding soil and the pile foundation is calculated. The dynamic stress field of the pile foundation near the operating subway and the soil around the pile foundation is solved, and the effective confining pressure σ borne by the pile foundation is obtained. p and dynamic stress σ d Among them, the confining pressure on the surrounding soil and pile foundation is σ p =γ′h·K0, the dynamic stress on the surrounding soil and pile foundation is σ d , γ′h is the soil pressure at depth h, γ′ is the effective weight of the soil, and K0 is the static earth pressure coefficient.

[0116] The work content of the soft soil parameter relationship construction module includes:

[0117] The mechanical properties of the soil in soft soil areas include shear strength, elastic modulus, shear modulus, undrained strength, dynamic shear strain, etc., which are inherent properties of the soil and are determined through experiments. Based on data analysis and equation fitting, the shear modulus G of saturated clay under different conditions is obtained. dand undrained strength S u The ratio of dynamic shear strain γ d Relationship

[0118] The softening coefficient δ is introduced and defined as the dynamic shear modulus G obtained under the Nth vibration cycle condition. dN The dynamic shear modulus G under the first vibration cycle condition d1 The ratio of the soil dynamic stress ratio CSR (CSR = σ d / σ p ) and softening coefficient δ(δ=G dN / G d1 ) and fitting to obtain the relationship δ=f(CSR).

[0119] Through data analysis, the soil dynamic shear strain γ is obtained d The relationship between the softening coefficient δ and the fitting equation δ=f(γ d ).

[0120] Combining the above relationship, the relationship between soil dynamic shear strain, soil dynamic stress ratio CSR and softening coefficient δ is obtained: d =f(CSR)=f(δ), combined with the work content of the soft soil parameter relationship construction module, we can get Where S u0 and G d0 For γ d For infinite hours S u and G d The value of .

[0121] The work contents of the pile foundation bearing capacity calculation module include:

[0122] Due to the daily operation of the subway, there are dynamic loads in the area along the subway line, which will affect the bearing capacity Q of the pile foundation. sk The influence of the pile foundation side bearing capacity is reduced, and the strength reduction rate of the pile foundation side bearing capacity under static force is defined as λ, that is, Q sk ′=λ·Q sk , where Q sk is the pile side bearing capacity without considering dynamic load, Q sk ′ is the pile side bearing capacity after dynamic load and reduction, and the calculation formula is: The work content of the soft soil parameter relationship construction module can be obtained

[0123] The reduced single pile vertical ultimate bearing capacity Q is obtained by using the general pile foundation single pile vertical ultimate bearing capacity formula and the regional pile foundation bearing capacity empirical formula.uk ′.

[0124] The work contents of the pile foundation bearing capacity loss calculation module include:

[0125] According to the reduced vertical ultimate bearing capacity of a single pile Q uk ′ and the vertical ultimate bearing capacity of a single pile without considering dynamic load Q uk , calculate the bearing capacity loss caused by dynamic loads, and determine the safety of the assessed pile foundation based on the single pile bearing capacity loss safety rating.

[0126] It should be noted that the steps in the method provided by the present invention can be implemented by using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the method to realize the composition of the system, that is, the embodiments in the method can be understood as preferred examples for constructing the system, which will not be elaborated here.

[0127] An embodiment of the present invention further provides a computer evaluation device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the device can be used to execute any method of the above-mentioned embodiments of the present invention, or to run any system of the above-mentioned embodiments of the present invention.

[0128] Optionally, the memory is used to store programs; the memory may include volatile memory (English: volatile memory), such as random-access memory (English: random-access memory, abbreviated: RAM), such as static random-access memory (English: static random-access memory, abbreviated: SRAM), double data rate synchronous dynamic random access memory (English: Double Data Rate Synchronous Dynamic Random Access Memory, abbreviated: DDR SDRAM), etc.; the memory may also include non-volatile memory (English: non-volatile memory), such as flash memory (English: flash memory). The memory is used to store computer programs (such as applications, functional modules, etc. that implement the above method), computer instructions, etc., and the above computer programs, computer instructions, etc. can be partitioned and stored in one or more memories. And the above computer programs, computer instructions, data, etc. can be called by the processor.

[0129] The above-mentioned computer programs, computer instructions, etc. may be stored in one or more memories in partitions, and the above-mentioned computer programs, computer instructions, data, etc. may be called by a processor.

[0130] The processor is used to execute the computer program stored in the memory to implement the various steps of the method or various modules of the system involved in the above embodiments. For details, please refer to the relevant descriptions in the above method and system embodiments.

[0131] The processor and the memory may be independent structures or integrated structures. When the processor and the memory are independent structures, the memory and the processor may be coupled and connected via a bus.

[0132] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it can be used to execute any method of the above embodiments of the present invention, or to run any system of the above embodiments of the present invention.

[0133] Among them, computer-readable media include computer storage media and communication media, wherein the communication media include any media that facilitates the transmission of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a general or special-purpose computer. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a user device. Of course, the processor and the storage medium can also be present in a communication device as discrete components.

[0134] The method and system for assessing the safety of pile foundation construction of new buildings along the subway provided in the above-mentioned embodiment of the present invention fully considers the poor engineering properties of soft soil by simulating the dynamic stress field of the existing subway operation, combining equation fitting and data analysis, and then provides a scientific basis for the safety assessment of pile foundations of new buildings around the subway through equation fitting; it simulates the dynamic impact of subway operation on the surrounding soil and pile foundations, fully considers the soil characteristics in soft soil areas, better assesses the long-term safety of pile foundations of new buildings along the subway, and provides an effective reference for the overall planning and risk control along the subway, ensuring the safety of subway operation and surrounding buildings.

[0135] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for assessing the safety of pile foundation construction of new buildings along subway lines, characterized in that: include: A numerical model of the pile foundation and the surrounding soil near the operating subway was established to obtain the stress field distribution around the pile foundation; Based on the stress field distribution around the pile foundation, a relationship model between the dynamic shear modulus and dynamic shear strain of the soil around the pile foundation and the mechanical property parameters of the soft soil is obtained; According to the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, a relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed; According to the relationship model between the dynamic stress of soft soil and the static strength reduction rate, combined with the empirical formula of pile side resistance, the reduced pile foundation bearing capacity is calculated; Based on the reduced pile foundation bearing capacity, the reduced pile foundation bearing capacity loss ratio is calculated to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

2. The method for safety assessment of pile foundation construction of new buildings along subway lines according to claim 1 is characterized in that: The numerical model of the pile foundation and the surrounding soil near the operating subway is established to obtain the stress field distribution around the pile foundation, including: According to the obtained subway data in the area to be tested, the running speed v of the subway in the area to be tested, the length L of the pile foundation of the new building in the area to be tested, and the distance D between the planned construction location of the pile foundation of the new building and the subway are determined, and a numerical model of the pile foundation and the surrounding soil of the subway in the area to be analyzed is established; The dynamic load caused by subway operation is applied to the numerical model to calculate the dynamic stress field distribution of the surrounding soil and pile foundation caused by the dynamic load of the subway train, and the stress field distribution of the soil around the pile foundation adjacent to the operating subway is obtained, where: The stress field distribution includes: the surrounding soil and pile foundation borne confining pressure σ p =γ′h·K0 and the dynamic stress σ borne by the surrounding soil and pile foundation d , where γ′h is the soil pressure at depth h, γ′ is the effective weight of the soil, and K0 is the static earth pressure coefficient.

3. The method for safety assessment of pile foundation construction of new buildings along subway lines according to claim 1 is characterized in that: The relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation is obtained based on the stress field distribution around the pile foundation, including: Based on the stress field distribution around the pile foundation, the dynamic stress ratio CSR = σ d / σ p , where σ d is the dynamic stress on the surrounding soil and pile foundation, σ p The confining pressure borne by the surrounding soil and pile foundation; Establish the dynamic shear modulus G of saturated soft soil under different conditions d and undrained strength S u The ratio of dynamic shear strain γ d The relationship model between Among them, G d is the dynamic shear modulus of soft soil, S u is the undrained shear strength of soft soil, γ d is the dynamic shear strain, p1 and k1 are fitting parameters; The softening coefficient δ is defined as the dynamic shear modulus G obtained under the Nth vibration cycle condition. dN The dynamic shear modulus G obtained under the first vibration cycle condition d1 ratio; establish dynamic stress ratio CSR = σ d / σ p and softening coefficient δ = G dN / G d1 The relationship between is δ=f(CSR)=p2·CSSR+k2, where p2 and k2 are fitting parameters; Establish soil dynamic shear strain γ d The relationship between the dynamic stress ratio CSR is: Among them, C and D are fitting parameters.

4. The method for safety assessment of pile foundation construction of new buildings along subway lines according to claim 1 is characterized in that: According to the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, a relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed, including: According to the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of soft soil around the pile foundation, including the dynamic shear modulus of saturated soft soil G d and undrained strength S u The ratio of dynamic shear strain γ d The relationship model between The relationship between dynamic stress ratio CSR and softening coefficient δ is δ = f(CSR), soil dynamic shear strain γ d Relationship between dynamic stress ratio CSRγ d =f(CSR), and the relationship model between the dynamic shear modulus, dynamic shear strain and mechanical property parameters of soft soil around the pile foundation and the static strength reduction rate is obtained. Among them, S u0 and G d0 For γ d is infinite, that is, γ d =γ d0 Time u and G d The value of G d0 For γ d =γ d0 The dynamic shear modulus, S u0 For γ d =γ d0 Undrained shear strength, γ d0 is an infinitesimal quantity, γ da is the dynamic shear strain of the soil at position a under dynamic stress, G da For γ d =γ da The dynamic shear modulus, S ua For γ d =γ da Undrained shear strength; Based on the stress field distribution around the pile foundation, substitute the relationship model δ=f(CSR),γ d =f(CSR), the relationship between the dynamic stress of soft soil and the static strength reduction rate can be finally obtained, that is, Relationship between S and dynamic stress ratio CSR ua , S u0 The relationship with CSR is:

5. The method for safety assessment of pile foundation construction of new buildings along subway lines according to claim 1 is characterized in that: The reduced pile foundation bearing capacity is calculated based on the relationship model between the soft soil dynamic stress and the static strength reduction rate, combined with the strength reduction rate of the pile foundation side bearing capacity under static conditions, including: Define the strength reduction rate of pile side bearing capacity under static force as λ, then Q sk ′=λ·Q sk ; Among them, Q sk is the pile side bearing capacity without considering dynamic load, Q sk ' is the pile side bearing capacity after dynamic load and reduction, The relationship model between dynamic stress and static strength reduction rate of soft soil We get λ = The reduced single pile vertical ultimate bearing capacity Q is obtained by using the general pile foundation single pile vertical ultimate bearing capacity formula and the regional pile foundation bearing capacity empirical formula. uk ′; the calculation formula for the vertical ultimate bearing capacity of a single pile of a general pile foundation is Q uk =Q sk +Q pk , Q sk is the pile side bearing capacity, Q pk is the ultimate end bearing capacity of the pile foundation. The empirical formula for the bearing capacity of the pile foundation in the region is a summary of the existing prior knowledge in each region. It can be obtained that Q pk =q·Q sk , where q is an empirical parameter; considering the strength reduction, the reduced pile side bearing capacity Q sk ′=λ·Q sk , the reduced vertical ultimate bearing capacity of a single pile can be calculated as Q′ uk =Q′ sk +q·Q sk =λ·Q sk +q·Q sk =(λ+q)Q sk .

6. The method for safety assessment of pile foundation construction of new buildings along subway lines according to claim 1 is characterized in that: The method of calculating the reduced pile foundation bearing capacity loss ratio according to the reduced pile foundation bearing capacity includes: Based on the reduced vertical ultimate bearing capacity of a single pile Q uk ′ and the vertical ultimate bearing capacity of a single pile without considering dynamic load Q uk , the ratio of the single pile bearing capacity loss caused by dynamic load is calculated as: Based on the single pile bearing capacity loss ratio, the safety of pile foundation construction of new buildings along the subway line is evaluated: Among them, m is the set warning threshold.

7. A safety assessment system for pile foundation construction of new buildings along subway lines, characterized in that: include: Dynamic stress field construction module, which is used to establish a numerical model of the pile foundation and the surrounding soil near the operating subway, and obtain the stress field distribution around the pile foundation; A soft soil parameter relationship building module, which obtains a relationship model between the dynamic shear modulus and dynamic shear strain of the soil around the pile foundation and the mechanical property parameters of the soft soil based on the dynamic stress field around the pile foundation; According to the relationship model of the dynamic shear modulus, dynamic shear strain and mechanical property parameters of the soil around the pile foundation, a relationship model between the dynamic stress of soft soil and the static strength reduction rate is constructed; A pile foundation bearing capacity calculation module, which is used to calculate the reduced pile foundation bearing capacity based on the relationship model between the soft soil dynamic stress and the static strength reduction rate and the empirical formula of the pile side resistance; The pile foundation bearing capacity loss calculation module is used to calculate the reduced pile foundation bearing capacity loss ratio according to the reduced pile foundation bearing capacity, so as to evaluate the safety rating of pile foundation construction of new buildings along the subway line.

8. A computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it can be used to perform the method described in any one of claims 1 to 6, or to run the system described in claim 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it can be used to perform the method described in any one of claims 1 to 6, or to run the system described in claim 7.

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