Evaluation method for loess flow slide impact masonry building vulnerability based on physical mechanism

Abstract

The present application relates to the technical field of geological disaster risk quantitative evaluation, and more particularly to a loess flow slide impact masonry building vulnerability evaluation method based on physical mechanism. The method comprises the following steps: obtaining geological background parameters and building structure parameters of a loess flow slide area; constructing a three-dimensional geological model of the loess flow slide based on the geological background parameters and the building structure parameters, and analyzing the three-dimensional motion process of the loess flow slide to obtain kinematic simulation results of the loess flow slide; and based on the kinematic simulation results of the loess flow slide and the building structure parameters, spatially matching the speed, height and impact direction of the slide body when moving to the location of the target building to obtain the impact speed, impact height and impact angle of the slide body. The present application improves the evaluation efficiency and accuracy by quantitatively analyzing the building vulnerability, and has wide engineering application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantitative evaluation of geological disaster risk, and particularly relates to a loess flow slide impact masonry building vulnerability evaluation method based on a physical mechanism. BACKGROUND

[0002] Loess flow slide has super strong high-speed flow movement characteristics, and a long movement distance, which often causes great impact damage to buildings along the way. The vulnerability analysis of buildings is an important link between disasters and risks, and is also the key and main technical bottleneck of loess flow slide disaster risk evaluation. In the prior art, the existing methods for evaluating the vulnerability of masonry buildings under the action of loess flow slide disasters mainly have the following deficiencies:

[0003] The vulnerability assessment of buildings is mostly focused on earthquake, slow landslide or flood disaster scenarios, and lacks targeted research on the impact effect of loess flow slide disasters caused by saturated sandy silt liquefaction in the rapid landslide of the Loess Plateau and on masonry buildings;

[0004] Loess flow slide has high speed and large impact force characteristics, and the traditional simplified analysis method ignores the spatial variability of flow slide movement parameters (speed, density, impact duration), and still lacks a quantitative characterization model of loess flow slide impact force;

[0005] Masonry structure materials are significantly brittle, and the damage evolution under dynamic impact is complex. The existing technology does not fully consider the dynamic coupling relationship between landslide dynamic impact and masonry structure response, and the vulnerability assessment results rely on empirical statistics, which has poor physical interpretability. SUMMARY

[0006] Therefore, it is necessary to provide a loess flow slide impact masonry building vulnerability evaluation method based on a physical mechanism to solve at least one of the above technical problems.

[0007] To achieve the above-mentioned purpose, a loess flow slide impact masonry building vulnerability evaluation method based on a physical mechanism comprises the following steps:

[0008] Step S1: Obtain the geological background parameters and building structure parameters of the loess flow slide area; based on the geological background parameters and building structure parameters, a three-dimensional geological model of loess flow slide is constructed, and the three-dimensional motion process of loess flow slide is analyzed to obtain kinematic simulation results of loess flow slide;

[0009] Step S2: based on the kinematic simulation results of loess flow slide and the building structure parameters, the speed, height and impact direction of the flow body movement to the target building position are spatially matched to obtain the impact speed, impact height and impact angle of the flow body;

[0010] Step S3: Perform a stress analysis on the masonry wall based on the impact velocity, impact height and impact angle of the sliding body, calculate the static pressure component and dynamic pressure component under the impact of the sliding body, and record them as impact pressure data; use the impact pressure data to calculate the shear response of the masonry wall components, and obtain the maximum shear force value of the loess flow on the masonry wall.

[0011] Step S4: Calculate the ultimate shear capacity of the masonry wall using the building's structural parameters and the maximum shear force value to obtain the ultimate shear strength value of the masonry wall;

[0012] Step S5: Based on the maximum shear force and the shear limit value, determine whether the masonry wall has failed and generate the global failure probability;

[0013] Step S6: Classify the building maintenance level based on the building structural parameters and set the maintenance correction coefficient for each classification; use the global failure probability and maintenance correction coefficient to determine the comprehensive vulnerability value of masonry buildings under loess slip impact.

[0014] This invention comprehensively considers the dynamic impact effect of loess landslides on masonry buildings and the bending failure mechanism of building walls. It develops calculation models for the maximum shear force and ultimate shear capacity of masonry walls under loess landslide impact. By quantifying the global failure probability of masonry buildings through the load-bearing type of the impacted wall and the building span, and by introducing a maintenance factor to correct for building vulnerability, this invention provides a quantitative building vulnerability assessment model that can significantly improve assessment efficiency and accuracy, and has broad engineering application prospects. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0016] Figure 1 This is a schematic diagram of the steps in the physical mechanism-based method for evaluating the vulnerability of loess flow-slide impact masonry buildings according to the present invention.

[0017] Figure 2 This is a flowchart of the method of the present invention;

[0018] Figure 3 This is a schematic diagram of the impact force on a masonry building in an embodiment of the present invention;

[0019] Figure 4 This is a panoramic view of the loess landslide disaster in an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram showing the movement speed and accumulation range of loess landslides in an embodiment of the present invention;

[0021] Figure 6This is a diagram showing the actual damage state of the building in an embodiment of the present invention. Detailed Implementation

[0022] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0024] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] To achieve the above objectives, please refer to Figures 1 to 6 This invention provides a method for evaluating the vulnerability of loess slip-impact masonry structures based on physical mechanisms. The method includes the following steps:

[0026] Step S1: Obtain the geological background parameters and building structure parameters of the loess landslide area; construct a three-dimensional geological model of the loess landslide based on the geological background parameters and building structure parameters, analyze the three-dimensional motion process of the loess landslide, and obtain the kinematic simulation results of the loess landslide.

[0027] Step S2: Based on the kinematic simulation results of loess landslide and the structural parameters of the building, spatial matching is performed on the velocity, height and impact direction of the landslide body at the location of the target building to obtain the impact velocity, impact height and impact angle of the landslide body;

[0028] Step S3: Perform a stress analysis on the masonry wall based on the impact velocity, impact height and impact angle of the sliding body, calculate the static pressure component and dynamic pressure component under the impact of the sliding body, and record them as impact pressure data; use the impact pressure data to calculate the shear response of the masonry wall components, and obtain the maximum shear force value of the loess flow on the masonry wall.

[0029] Step S4: Calculate the ultimate shear capacity of the masonry wall using the building's structural parameters and the maximum shear force value to obtain the ultimate shear strength value of the masonry wall;

[0030] Step S5: Based on the maximum shear force and the shear limit value, determine whether the masonry wall has failed and generate the global failure probability;

[0031] Step S6: Classify the building maintenance level based on the building structural parameters and set the maintenance correction coefficient for each classification; use the global failure probability and maintenance correction coefficient to determine the comprehensive vulnerability value of masonry buildings under loess slip impact.

[0032] Preferably, step S1 includes the following steps:

[0033] Step S11: Collect topographic raster data, landslide source area range and thickness, and landslide kinematic parameters of the loess landslide area at a resolution of 1-2m using UAV aerial surveying, and record them as geological background parameters;

[0034] Step S12: Obtain the spatial distribution, length, width, number of floors, floor height, span, and masonry wall thickness of the building through on-site measurements, and record them as building structural parameters;

[0035] Step S13: Determine the volume of loess flow based on the extent and thickness of the landslide source area;

[0036] Step S14: Construct a three-dimensional geological model of the loess landslide area based on the terrain raster data and the loess landslide volume, and use the landslide kinematic parameters to perform a three-dimensional motion simulation of the landslide body on the three-dimensional geological model to obtain the loess landslide kinematic simulation results.

[0037] In this embodiment of the invention, a multi-rotor UAV equipped with a high-precision optical imaging sensor and a differential global positioning system (RTK-GNSS) is used to conduct low-altitude aerial surveys of the target loess landslide area. The survey altitude is controlled between 80 and 120 meters, with lateral and directional overlap maintained at over 80% to ensure the accuracy of the generated digital terrain model. Photogrammetric software is used to perform aerial triangulation and stereo matching on the acquired images, generating terrain raster data with a resolution of 1 to 2 meters. Combined with the boundary and depth data of the landslide source area obtained from on-site surveys, the planar extent (unit: square meters) and thickness (unit: meters) of the landslide source area are accurately delineated. Soil sampling points are set up on-site, and the natural density (unit: meters) of the loess is determined using the ring sampler method. The Coulomb friction coefficient was obtained by considering humidity, shear strength, and on-site slope friction plate tests. (Value range: 0.25 to 0.35), turbulent friction coefficient (Value range 250 to 350) ) and yield strength (Values ​​range from 1.8 to 2.2 kPa), and the above data are recorded as geological background parameters. Subsequently, a total station and laser rangefinder are used to measure each building within the target area, obtaining the building's planar coordinates and relative elevation information. A measuring tape and laser rangefinder are used to determine the length (in meters), width (in meters), number of floors (integer value), floor height (in meters), span (in meters), and masonry wall thickness (in meters) of each building, and these are stored in the form of building numbers to form building structural parameters. Based on the planar extent of the landslide source area obtained in step S11... (unit: ) and thickness (Unit: m) Calculate the volume of the sliding body. (unit: ) through formula It is concluded that, among them and All data originates from on-site surveys and soil sample depth measurements, and this volumetric data is directly used as the basic input for 3D modeling. The terrain raster data obtained in step S11 is overlaid with the landslide volume calculated in step S13, and a 3D geological model of loess flow landslide containing the initial geomorphic features of the landslide source area is generated using 3D terrain modeling software (such as a terrain reconstruction module based on TIN triangulation). The Coulomb friction coefficient measured in step S11 is incorporated into this model. turbulent friction coefficient and yield strength The simulation method simulates the entire process of a landslide moving downhill from the landslide source area through step-by-step iteration. It calculates the centroid position, local velocity field, and thickness change of the landslide at each time step until the landslide is stably deposited. The final output is the kinematic simulation results of loess landslide, which includes the velocity distribution, impact thickness distribution, and movement path of the landslide at the locations of various structures.

[0038] Preferably, step S2 includes the following steps:

[0039] Step S21: Perform spatial analysis on the kinematic simulation results of loess landslide, extract the motion path and velocity field information of the landslide body, and obtain the data set of the landslide body motion trajectory at the location where the landslide body reaches the building;

[0040] Step S22: Based on the sliding body trajectory dataset and the spatial distribution of buildings, perform spatial overlay analysis on the sliding body path and building boundaries to obtain the impact intersection point of the sliding body acting on the building wall;

[0041] Step S23: Perform a cut-off analysis of the sliding body velocity field at the impact intersection point to obtain the impact velocity of the sliding body at that location;

[0042] Step S24: Based on the landslide accumulation data and building height from the loess landslide kinematic simulation results, perform a cross-sectional analysis on the vertical thickness at the impact intersection point to obtain the impact height;

[0043] Step S25: Calculate the impact angle between the sliding body and the wall based on the impact velocity and impact height.

[0044] In this embodiment of the invention, the kinematic simulation results of loess landslides obtained in step S14 are imported into a geographic information processing platform (such as ArcGIS Pro or QGIS) with three-dimensional spatial analysis capabilities. The flow direction analysis and velocity field extraction functions in the spatial analysis module are invoked. Combined with the time-series data output from the simulation, the centroid coordinates, unit velocity vectors, and thickness information of the landslide at each time step are processed to generate a raster dataset containing the complete landslide path and corresponding velocity field. Records of landslides moving to the area where buildings are located are then filtered out to obtain a landslide trajectory dataset at the location where the landslide reaches the building. The above landslide trajectory dataset is then spatially overlaid with the building spatial distribution vector data (building outlines and wall positioning lines) obtained in step S12. Through vector-raster intersection operations, the location where the landslide path first intersects with the building's outer wall is accurately determined. This location is marked as the impact intersection point, and its planar coordinates (unit: meters) are recorded. Using the planar coordinates of the impact intersection point, the velocity field data generated in step S21 is truncated, and the three velocity components at that location are extracted. , , and use the formula The impact velocity of the sliding body at the impact location was calculated. (Unit: m / s) This is used as the input parameter for dynamic impact pressure in subsequent stress analysis. The section analysis tool is called to vertically section the landslide accumulation thickness data from the loess landslide kinematic simulation results. The sectioning plane is based on the plane coordinates of the impact intersection point, and the sectioning direction is perpendicular to the ground surface. This is combined with the building floor height obtained in step S12. (Unit: m), accurately measure the vertical thickness of the sliding body in contact with the wall at this location. (Unit: m), this thickness will be used for calculating the static impact pressure. The impact velocity vector obtained in step S23 will be used... The unit normal vector determined by the outward direction of the building's exterior walls. Perform angle calculations using the formula. The impact angle between the sliding body and the wall was calculated. (Unit: °), where the vector dot product reflects the cosine relationship between the velocity direction and the normal vector.

[0045] Preferably, the calculation formula for the static pressure component in step S3 is as follows:

[0046] ;

[0047] in, For static pressure, This is the static pressure coefficient, typically set to 1. The density of loess slippage, It is the acceleration due to gravity. The length of the masonry wall impacted by loess slippage. The thickness of the loess landslide impact body.

[0048] In this embodiment of the invention, the impact height of the sliding body is first completed in step S2. Length of impact-affected masonry wall After obtaining the data, it is used as the core geometric parameter input for static pressure calculation; the density of loess slippage. Soil samples were obtained through the ring sampling points set up in step S11, and their mass and volume were accurately calculated after being measured indoors using the constant volume drying method, with the values ​​controlled within the range of 1700. By 1900 gravitational acceleration Fixed at 9.81 Static pressure coefficient A value of 1 is used according to engineering specifications to ensure calculation consistency. During the calculation process, all parameters are input into the static pressure formula using structural mechanics calculation tools:

[0049] ;

[0050] in, The unit is N / m (linear pressure along the length of the wall). The value is derived from the building structure measurement results (unit: meters) in step S12. The value is derived from the vertical sectioning analysis results in step S24 (unit: meters). In practical operation, for example when... , , When calculating, substitute the parameters into the formula, first square the impact thickness. Multiply by the length of the wall that was impacted. Gravitational acceleration With density Finally, multiply by the static pressure coefficient. With coefficient The static pressure value of the masonry wall under the impact of loess flow can be obtained.

[0051] Preferably, the calculation formula for the dynamic pressure component in step S3 is as follows:

[0052] ;

[0053] in, For dynamic impact pressure, and For dimensionless parameters, For impact velocity, For the impact angle.

[0054] In this embodiment of the invention, the impact velocity at the impact intersection point is first obtained in step S23. (Unit: m / s) After that, it is used as the core dynamic input, and combined with the impact angle calculated in step S25. (Unit: °), Thickness of loess landslide impact body obtained from step S24 cross-sectional analysis (Unit: m) and the length of the impacted masonry wall measured in step S12. (Unit: m), and the loess flow density determined by the indoor test in step S11 is used. (Value range 1700–1900) ); Dimensionless parameters and In the embodiment, existing loess landslide impact test data within the reference area were fixed through regression analysis. , To ensure consistency with the measured dynamic response; gravitational acceleration Take 9.81 Input all the above parameters into the dynamic impact pressure calculation formula:

[0055] ;

[0056] in, The unit is N / m (linear pressure along the length of the wall). In the calculation process, the thickness is first determined... With gravitational acceleration Seeking Then calculate the speed ratio. and take Power, and parameters Multiplying them yields a dimensionless magnification factor; then it is multiplied by the density. Impact velocity square , Length of the impact wall and impact thickness Multiplying these values ​​yields the dynamic impact pressure value of the masonry wall under the impact of loess slippage. For example, in a certain field measurement, , , , , Under the given conditions, the dynamic impact pressure at that location can be obtained by substituting the numerical values ​​into the formula and performing the calculations sequentially.

[0057] Preferably, the formula for calculating the maximum shear force in step S3 is as follows:

[0058] ;

[0059] in, This represents the maximum shear force of the masonry wall. For the building's floor height, For static pressure, For dynamic impact pressure, The thickness of the loess landslide impact body.

[0060] In this embodiment of the invention, the static pressure components are first calculated separately. (Unit: N / m) and dynamic impact pressure component (Unit: N / m), both act along the length of the impacted masonry wall; subsequently, the thickness of the loess flow-slide impact body was obtained through vertical section analysis. (Unit: meters) In step S12, the building floor height is accurately measured during the architectural survey. (Unit: m). In actual calculations, the above four parameters are used as inputs. Based on the mechanical characteristics of masonry walls under bending stress during dynamic impact, the maximum shear force at the bottom of the masonry wall is calculated using the following formula:

[0061] ;

[0062] Among them, the first item This represents the integral result of the shear force distribution generated by dynamic impact pressure within the wall height range, reflecting the geometric relationship between impact thickness and story height; the second term This represents the shear force contribution generated when static pressure is uniformly distributed throughout the wall height. In practice, for example, in a calculation, it is assumed that... , , , First, substitute the parameters into the dynamic term for calculation. Then calculate the static terms: Summing the two parts yields the maximum shear force of the masonry wall under the impact of loess slippage. .

[0063] Preferably, the formula for calculating the shear limit value of the masonry wall in step S4 is as follows:

[0064] ;

[0065] in, This represents the ultimate shear capacity of the masonry wall. This represents the total shear strength of the masonry wall. This represents the cross-sectional width of the masonry wall. Let the force arm be the internal lever arm of the masonry wall section when the section is rectangular. Values , The thickness of the masonry wall; The design value for the shear strength of masonry can be determined based on the recommended shear strength values ​​for different grades of mortar. The density of the masonry wall. The internal friction angle of the masonry wall at the point of failure along its cross-section. For the number of building floors, For the width of the building, For floor slab thickness, This refers to the floor slab density.

[0066] In this embodiment of the invention, the length of the impacted masonry wall obtained in step S12 using a total station and a laser rangefinder is used. Masonry wall thickness Building floor height Building width Floor slab thickness With number of layers The dry density of the masonry material was determined by sampling with a ring sampler and using the constant-volume drying method. The density range is limited to 1800–2200. The density of the floor slab was determined by core sampling of the concrete, followed by drying and weighing. The density range is limited to 2400–2600. Design value of masonry shear strength The value is determined according to the corresponding mortar grade in the "Code for Design of Masonry Structures" (GB50003-2011). In the examples, the commonly used value range is 0.08 MPa–0.15 MPa. Example values ​​are provided. = 0.11 MPa; Angle of internal friction when masonry fails along the cross-section The value was obtained through indoor direct shear tests. The peak friction angle was measured using standard-sized specimens and a constant-speed loading device, with a range of 30°–40°. The force arm within the cross-section was also determined. When the cross-section is rectangular, calculate and substitute the following formula into subsequent calculations for gravitational acceleration. The cross-sectional width is denoted as , Take the effective length of the impacted wall along the horizontal direction. After obtaining the above parameters, calculate the total shear strength of the masonry wall item by item according to the following formula. With ultimate shear capacity .

[0067] Preferably, in step S5, the determination of whether the masonry wall has failed based on the maximum shear force value and the shear limit value, and the generation of the global failure probability, include:

[0068] Obtain the masonry wall type, which includes load-bearing wall structure and non-load-bearing wall structure;

[0069] Calculate the overall collapse probability of masonry buildings under loess flow impact based on the maximum shear force, shear limit value and masonry wall type;

[0070] If the masonry wall subjected to impact is a load-bearing wall structure, the specific calculation process for the global failure probability of the masonry building is as follows:

[0071] ;

[0072] in, This represents the global failure probability. This is the maximum shear force value. This is the shear limit value. This represents the span of the masonry wall;

[0073] If the masonry wall subjected to impact is a non-load-bearing wall structure, the specific calculation process for the global failure probability of the masonry building is as follows:

[0074] ;

[0075] in, This represents the global failure probability. This is the maximum shear force value. This represents the shear limit value.

[0076] In this embodiment of the invention, the type of masonry wall is first determined by consulting the building's vertical structural drawings and construction plan, combined with on-site structural verification. The determination rule is: when the wall bears the load of the floor slab or beam in the vertical structural drawings and forms a continuous force transfer path with the foundation or floor structure, it is identified as a load-bearing wall; when design data is missing, on-site measurement and component node inspection are used for determination, with steel tape measures or laser rangefinders used to obtain the wall thickness. (Unit: m), the engineering judgment threshold is It is then considered a load-bearing wall. If so, it is identified as a non-load-bearing wall. The continuity of the wall and the joints are confirmed by hammering and listening and visual inspection, and recorded as building structural parameters; then, the maximum shear force value output in step S3 is read. (Unit: N) and the shear limit value output in step S4 (Unit: N), and read the building span. (positive integer, The global failure probability is calculated using the following formula based on the wall type. If it is a load-bearing wall, calculate according to the formula. If it is a non-load-bearing wall, calculate according to the formula. ; Calculation requirements and When measured or calculated At that time, set ; Calculated It should be limited to closed intervals. Within this scope, if the calculated value is less than 0, it is taken as 0; if the calculated value is greater than 1, it is taken as 1. For ease of engineering verification, the calculation process and results should be recorded as entries in the structural parameter table and linked to the engineering database using the building number. Simultaneously, a table or layer should be generated for display to facilitate subsequent processing. An example is provided to illustrate the process. , , When load-bearing walls are used After being restricted When it is a non-load-bearing wall .

[0077] Preferably, in step S6, the building maintenance level is classified based on the building structural parameters, and maintenance correction coefficients are set for each classification, including:

[0078] The service life, apparent maintenance condition and component integrity of a building are assessed based on its structural parameters, and the maintenance level is classified to obtain maintenance status labels, which include good, average and poor.

[0079] A coefficient is set for each label in the maintenance status label to obtain the corresponding maintenance correction coefficient. The better maintenance correction coefficient is 0.8, the average maintenance correction coefficient is 0.9, and the poor maintenance correction coefficient is 1.0.

[0080] In this embodiment of the invention, step S6 first assesses the building's service life, apparent maintenance condition, and component integrity based on the building structural parameters obtained in step S12, using a combination of quantitative and qualitative methods. The service life is obtained by reviewing building completion archives and property registration information. If these archives are unavailable, the carbonation depth method for concrete is used for estimation. The carbonation depth is measured using vernier calipers on the protected section, with an error controlled within ±0.5 mm, and then converted to years. The assessment range is [insert range here]. 20 years, 20–40 years The 40-year, three-tiered assessment; the appearance and maintenance condition are determined by taking close-up photographs of the building's exterior walls, roof, doors, and windows under natural light conditions using a high-resolution digital camera, and then using image recognition technology to determine the area proportion of defects such as peeling, cracks, and water seepage. 5% is defined as mild, and 5%–15% is defined as moderate. 15% is defined as severe; the integrity of components is determined by conducting strength and corrosion tests on key load-bearing components (including masonry walls, floor slabs, beams, and columns) using on-site structural testing tools (such as rebound hammers and rebar detectors). The results are converted into a percentage of integrity according to the "Technical Standard for Building Structure Testing" (GB / T 50344-2019). 90% is considered intact, and 75%–90% is considered fair. 75% is considered poor. The three indicators mentioned above are weighted and scored according to their respective weighting ratios (service life 30%, apparent maintenance condition 40%, component integrity 30%), with the scoring range... A score of 85 is marked as "good", and a score of 70–85 is marked as "average". A score of 70 is marked as "poor," which is the maintenance status label. A maintenance correction factor is assigned based on this maintenance status label. Where “better” corresponds to "General" corresponds to "Poor" corresponds to .

[0081] Preferably, step S6, which uses the global failure probability and maintenance correction coefficient to determine the comprehensive vulnerability value of masonry buildings under loess slip impact, includes:

[0082] The comprehensive vulnerability value of masonry buildings under loess slip impact is obtained by multiplying the global failure probability and the maintenance correction coefficient. The specific calculation formula is as follows:

[0083] ;

[0084] in, To assess the overall vulnerability value, This represents the global failure probability. To maintain the correction factor.

[0085] In this embodiment of the invention, taking into account the impact damage mechanism of loess landslides on masonry buildings, the failed wall structures, and the building's maintenance status, the final comprehensive vulnerability calculation model for masonry buildings under the impact of loess landslides is as follows: .

[0086] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is not limited by the foregoing description. Thus, all changes falling within the meaning and scope of the equivalents of the application are intended to be included within the scope of the invention.

[0087] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for evaluating the vulnerability of loess slip-impact masonry structures based on physical mechanisms, characterized in that, Includes the following steps: Step S1: Obtain the geological background parameters and building structure parameters of the loess landslide area; A three-dimensional geological model of loess landslide was constructed based on geological background parameters and building structural parameters. The three-dimensional motion process of loess landslide was analyzed, and the kinematic simulation results of loess landslide were obtained. Step S2: Based on the kinematic simulation results of loess landslide and the structural parameters of the building, spatial matching is performed on the velocity, height and impact direction of the landslide body at the location of the target building to obtain the impact velocity, impact height and impact angle of the landslide body; Step S3: Perform a stress analysis on the masonry wall based on the impact velocity, impact height and impact angle of the sliding body, calculate the static pressure component and dynamic pressure component under the impact of the sliding body, and record them as impact pressure data; use the impact pressure data to calculate the shear response of the masonry wall components, and obtain the maximum shear force value of the loess flow on the masonry wall. Step S4: Calculate the ultimate shear capacity of the masonry wall using the building's structural parameters and the maximum shear force value to obtain the ultimate shear strength value of the masonry wall; The specific formula for calculating the shear limit value of the masonry wall in step S4 is as follows: ； in, This represents the ultimate shear capacity of the masonry wall. This represents the total shear strength of the masonry wall. This represents the cross-sectional width of the masonry wall. Let the force arm be the internal lever arm of the masonry wall section when the section is rectangular. Values , The thickness of the masonry wall; The design value for the shear strength of masonry can be determined based on the recommended shear strength values ​​for different grades of mortar. The density of the masonry wall. The internal friction angle of the masonry wall at the point of failure along its cross-section. For the number of building floors, For the width of the building, For floor slab thickness, For floor slab density, It is the acceleration due to gravity. For the building's floor height, It is a dimensionless parameter; Step S5: Based on the maximum shear force and the ultimate shear strength, determine whether the masonry wall has failed and generate the global failure probability, including: calculating the overall collapse probability of the masonry building under the impact of loess flow based on the maximum shear force, the ultimate shear strength, and the type of masonry wall; Step S6: Classify the building maintenance level based on the building structural parameters and set the maintenance correction coefficient for each classification; use the global failure probability and maintenance correction coefficient to determine the comprehensive vulnerability value of masonry buildings under loess slip impact.

2. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Collect topographic raster data, landslide source area range and thickness, and landslide kinematic parameters of the loess landslide area at a resolution of 1-2m using UAV aerial surveying, and record them as geological background parameters; Step S12: Obtain the spatial distribution, length, width, number of floors, floor height, span, and masonry wall thickness of the building through on-site measurements, and record them as building structural parameters; Step S13: Determine the volume of loess flow based on the extent and thickness of the landslide source area; Step S14: Construct a three-dimensional geological model of the loess landslide area based on the terrain raster data and the loess landslide volume, and use the landslide kinematic parameters to perform a three-dimensional motion simulation of the landslide body on the three-dimensional geological model to obtain the loess landslide kinematic simulation results.

3. The method for evaluating the vulnerability of loess slip-impact masonry structures based on physical mechanisms according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Perform spatial analysis on the kinematic simulation results of loess landslide, extract the motion path and velocity field information of the landslide body, and obtain the data set of the landslide body motion trajectory at the location where the landslide body reaches the building; Step S22: Based on the sliding body trajectory dataset and the spatial distribution of buildings, perform spatial overlay analysis on the sliding body path and building boundaries to obtain the impact intersection point of the sliding body acting on the building wall; Step S23: Perform a cut-off analysis of the sliding body velocity field at the impact intersection point to obtain the impact velocity of the sliding body at that location; Step S24: Based on the landslide accumulation data and building height from the loess landslide kinematic simulation results, perform a cross-sectional analysis on the vertical thickness at the impact intersection point to obtain the impact height; Step S25: Calculate the impact angle between the sliding body and the wall based on the impact velocity and impact height.

4. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, The specific formula for calculating the static pressure component in step S3 is as follows: ； in, For static pressure, This is the static pressure coefficient, with a value of 1. The density of loess slippage, It is the acceleration due to gravity. The length of the masonry wall impacted by loess slippage. The thickness of the loess landslide impact body.

5. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, The specific formula for calculating the dynamic pressure component in step S3 is as follows: ； in, For dynamic impact pressure, and For dimensionless parameters, For impact velocity, To achieve the impact angle, The density of loess slippage, It is the acceleration due to gravity. The length of the masonry wall impacted by loess slippage. The thickness of the loess landslide impact body.

6. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, The specific formula for calculating the maximum shear force in step S3 is as follows: ； in, This represents the maximum shear force of the masonry wall. For the building's floor height, For static pressure, For dynamic impact pressure, The thickness of the loess landslide impact body.

7. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, Step S5, based on the maximum shear force and the shear limit value, determines whether the masonry wall has failed, and generates the global failure probability, which also includes: Obtain the masonry wall type, which includes load-bearing wall structure and non-load-bearing wall structure; If the masonry wall subjected to impact is a load-bearing wall structure, the specific calculation process for the global failure probability of the masonry building is as follows: ； in, This represents the global failure probability. This is the maximum shear force value. This is the shear limit value. This represents the span of the masonry wall; If the masonry wall subjected to impact is a non-load-bearing wall structure, the specific calculation process for the global failure probability of the masonry building is as follows: ； in, This represents the global failure probability. This is the maximum shear force value. This represents the shear limit value.

8. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, In step S6, the building maintenance level is classified based on the building's structural parameters, and maintenance correction coefficients are set for each classification, including: The service life, apparent maintenance condition and component integrity of a building are assessed based on its structural parameters, and the maintenance level is classified to obtain maintenance status labels, which include good, average and poor. A coefficient is set for each label in the maintenance status label to obtain the corresponding maintenance correction coefficient. The better maintenance correction coefficient is 0.8, the average maintenance correction coefficient is 0.9, and the poor maintenance correction coefficient is 1.

0.

9. The method for evaluating the vulnerability of loess landslide impact masonry structures based on physical mechanisms according to claim 1, characterized in that, Step S6 involves determining the comprehensive vulnerability value of masonry structures under loess slip impact using the global failure probability and maintenance correction coefficient, including: The comprehensive vulnerability value of masonry buildings under loess slip impact is obtained by multiplying the global failure probability and the maintenance correction coefficient. The specific calculation formula is as follows: ； in, To assess the overall vulnerability value, This represents the global failure probability. To maintain the correction factor.

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