A building foundation partition reinforcing decision method based on drop hammer deflection detection

Abstract

This invention discloses a method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection. The method includes: dividing the construction site into multiple evaluation units according to equipment operation areas and binding spatial coordinates with construction load information; applying transient impact loads to each unit and collecting dynamic vertical displacements at the load center and different radial distances to form a spatial distribution curve of the deflection basin; extracting the maximum central deflection, deflection basin area parameters, and the coefficient of variation of the foundation's dynamic modulus; determining the weight of each evaluation parameter based on load type characteristics and integrating them into a comprehensive risk index; classifying risk levels according to this index and matching differentiated reinforcement measures; retesting the reinforced units and determining whether they meet the standards based on the improvement coefficient calculated from the dynamic modulus before and after reinforcement. This invention achieves data-driven zonal risk identification and precise reinforcement of foundations, solving the problems of strong subjectivity and waste of overall reinforcement resources in traditional experience-based judgments, and improving construction safety and the economy of foundation treatment.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering foundation testing and treatment technology, specifically relating to a method for decision-making on zonal reinforcement of building foundations based on falling weight deflection testing. Background Technology

[0002] During construction, pile foundation equipment, hoisting machinery, and transport vehicles exert significant loads on the site foundation, especially around the foundation pit, backfilled areas, and areas with weak soil foundations, which can easily lead to construction safety risks such as equipment settlement, localized settlement, and foundation instability. Currently, three methods are commonly used on construction sites to address these issues: first, experience-based judgment, determining the scope of treatment based on on-site settlement conditions, which suffers from strong subjectivity and difficulty in assessing the extent of impact; second, localized static load testing, which suffers from long testing cycles, a limited number of test points, and difficulty in meeting the needs of rapid decision-making during the construction phase; and third, overall reinforcement treatment, which suffers from excessively large treatment areas, increased costs, and waste of resources.

[0003] Falling weight deflectometers (FWD) can quickly acquire the dynamic deformation response of a foundation under impact loads. However, current technology is mainly used for road structure evaluation and subgrade quality inspection. Its data processing is based on the theory of elastic layered systems, obtaining the elastic modulus of the pavement structure layers through back-calculation, and then evaluating the long-term service performance and fatigue life of the pavement structure. However, road engineering projects are subjected to moving distributed loads, repeated actions, and standard axle loads, with the evaluation objective being the long-term decay law of the structure's bearing capacity. In contrast, construction sites bear concentrated quasi-static heavy loads from large equipment such as pile drivers and crawler cranes, with deformation mechanisms primarily consisting of local shear and instantaneous compression, focusing on short-term safety and equipment operability during the construction period. When existing FWD evaluation models based on road engineering are directly applied to construction sites, due to the systematic differences in load mechanisms and deformation control objectives, it is difficult to accurately reflect the actual risk status of the construction site. Furthermore, current technology lacks an integrated decision-making method for dynamic deflection spatial distribution analysis, risk zone delineation, and automatic matching of reinforcement measures for construction sites. Traditional testing methods only output single-point test values, requiring testing personnel to make handling suggestions based on experience. They cannot achieve automatic mapping of "test results → risk level → handling measures" and lack a mechanism for verifying the effectiveness of reinforcement.

[0004] Therefore, it is necessary to propose a method based on dynamic deflection detection results, taking into account the differences in construction load types, to achieve risk identification, spatial zoning, and differentiated reinforcement decisions for building foundations. Summary of the Invention

[0005] In view of this, the present invention proposes a method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection. To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection, comprising: The construction site is divided into multiple evaluation units according to the equipment operation area, and each unit is bound to spatial coordinates and construction load information. Transient impact loads are applied to each unit, and dynamic vertical displacements at the load center and different radial distances are collected to form the spatial distribution curve of the deflection basin. Based on the spatial distribution curve of the deflection basin, the maximum central deflection, the area parameters of the deflection basin, and the coefficient of variation of the dynamic modulus of the foundation are extracted and combined into the first type of parameters. The first type of parameters are integrated with the construction load information to form a comprehensive risk index. The integration process determines the weight allocation method of each evaluation parameter based on the load type characteristics in the construction load information. Based on the comprehensive risk index, each unit is divided into multiple risk levels, and differentiated reinforcement measures with corresponding reinforcement strengths are matched according to the risk level. The reinforced units are retested, and the improvement coefficient is calculated based on the dynamic modulus before and after reinforcement to determine whether the preset standard is met.

[0006] Preferably, the evaluation unit is divided as follows: the grid side length of the evaluation unit is determined according to the track length or outrigger span of the construction equipment, so that the size of a single evaluation unit is related to the characteristic size of the ground contact area of ​​the construction equipment; wherein, the construction equipment operation area includes at least one of the following: the pile driver travel route area, the pile driver pile driving operation station area, the crane hoisting station area, the heavy transport vehicle passage road area, and the temporary material storage area; the construction load information includes equipment type, ground pressure value, and load frequency characteristics. When there are multiple construction equipment in the same evaluation unit, the load value corresponding to the most unfavorable load condition is taken.

[0007] Preferably, the spatial distribution curve of the deflection basin is formed as follows: Multiple displacement sensors are arranged at the load center and at different radial distances from the load center to simultaneously acquire the vertical displacement response in the near and far regions of the load center. The radial spacing of each sensor is smaller near the load center than far from the load center to obtain higher sampling resolution in the near region where the curvature of the deflection basin changes the most. Each evaluation unit performs multiple independent tests and takes the arithmetic mean of the test results as the spatial distribution curve of the deflection basin for that evaluation unit. During the test, the ambient temperature and surface moisture content are recorded simultaneously. When the ambient temperature exceeds the preset temperature range or the surface moisture content exceeds the preset moisture content range, the obtained data is corrected for temperature and moisture content.

[0008] Preferably, the extraction method for the first type of parameters is as follows: the maximum central deflection is taken as the peak displacement at the center of the load, which is used to characterize the overall stiffness of the foundation; the deflection basin area parameter is obtained by integrating the spatial distribution curve of the deflection basin over the radial distance, which is used to characterize the spatial influence range of the load in the foundation; the foundation dynamic modulus is calculated based on the elastic layered system theory, according to the peak displacement at the center of the load, the peak value of the impact load, and the geometric dimensions of the bearing plate, wherein a correction coefficient is applied to the back-calculation results according to the foundation soil type to eliminate the deviation between theoretical assumptions and actual soil response; the coefficient of variation of the foundation dynamic modulus is the ratio of the standard deviation to the mean of multiple foundation dynamic modulus data obtained from multiple tests within the same evaluation unit, which is used to characterize the spatial uniformity of the foundation.

[0009] Preferably, the integration method of the comprehensive risk index is as follows: each evaluation parameter is normalized to a unified dimension and then combined into a comprehensive index by weighted summation; wherein, the weight coefficients used in the weighted summation are determined according to the load type of the construction equipment. When the construction equipment is a hammer-type equipment that generates high-frequency impact loads, the weights of the maximum central deflection parameter and construction load information are increased to highlight the dominant role of dynamic response and load amplitude. When the construction equipment is a static pressure type equipment that generates low-frequency static pressure loads, the weights of the deflection basin area parameter and the coefficient of variation of the foundation dynamic modulus are increased to highlight the dominant role of the load influence range and foundation uniformity; the weight coefficients are determined by a multi-criteria decision analysis method.

[0010] Preferably, it also includes: based on the load action mechanism characteristics reflected by the currently determined weight coefficients, calling the theoretical deflection basin shape template corresponding to the load action mechanism characteristics; substituting the foundation dynamic modulus and the maximum central deflection of the evaluation unit into the theoretical deflection basin shape template to generate the expected deflection basin spatial distribution curve adapted to the mechanical parameters of the evaluation unit. The expected spatial distribution curve of the deflection basin is compared with the actual spatial distribution curve of the deflection basin in three dimensions: deflection basin depth characteristics, deflection basin width characteristics, and deflection basin curvature attenuation characteristics. The depth deviation component, width deviation component, and curvature deviation component are calculated respectively. The source of deviation is identified based on the relative magnitudes of the depth deviation component, width deviation component, and curvature deviation component: when the depth deviation component is dominant and the width and curvature deviation components are within the normal range, the detection data is deemed abnormal, triggering a re-detection instruction; when the width or curvature deviation component is dominant and the depth deviation component is within the normal range, the load type characteristics are deemed mismatched with the actual load response mechanism of the evaluation unit, triggering a weight configuration anomaly warning and instructing a re-verification of the load type characteristics; when all three deviation components exceed the normal range, the evaluation unit is deemed to have a hidden geological anomaly that does not conform to the current stratigraphic structure assumptions corresponding to the weight configuration, triggering a supplementary exploration instruction. The depth deviation component, width deviation component, and curvature deviation component are weighted and fused according to the sensitivity coefficients corresponding to the weights of each evaluation parameter in the weighting coefficient to obtain the morphological deviation index.

[0011] Preferably, the risk level is divided as follows: multiple risk thresholds are preset, including a first risk threshold and a second risk threshold, wherein the first risk threshold is lower than the second risk threshold; when the comprehensive risk index of the evaluation unit does not exceed the first risk threshold, it is classified as a low-risk level; when the comprehensive risk index exceeds the first risk threshold but does not exceed the second risk threshold, it is classified as a medium-risk level; and when the comprehensive risk index exceeds the second risk threshold, it is classified as a high-risk level. The first and second risk thresholds are obtained by calibrating the comprehensive risk index of a reference evaluation unit with known good foundation performance and a reference evaluation unit with known poor foundation performance in the same construction site, so that the risk thresholds are adaptively matched with the actual geological conditions and foundation performance level of the site.

[0012] Preferably, the matching method for differentiated reinforcement measures is as follows: Low-risk levels are matched with no additional reinforcement measures and construction is organized according to the original construction plan; medium-risk levels are matched with Category I reinforcement measures, which include at least one of the following: laying steel plates to spread the load, laying a crushed stone cushion layer to improve bearing capacity, or implementing compaction treatment to improve surface density; high-risk levels are matched with Category II reinforcement measures, where the reinforcement strength of Category II reinforcement measures is higher than that of Category I reinforcement measures. Category II reinforcement measures include at least one of the following: replacement treatment by excavating and backfilling and compacting the weak soil layer, grouting reinforcement by injecting cementitious materials into the foundation, or composite foundation treatment by forming a reinforcement body in the foundation; wherein, the thickness of the steel plate or the thickness of the crushed stone cushion layer in Category I reinforcement measures is determined based on the extent to which the comprehensive risk index of the evaluation unit exceeds the lower limit threshold of the medium-risk level.

[0013] Preferably, the method for calculating and determining the enhancement coefficient is as follows: The enhancement coefficient is the ratio of the dynamic modulus of the foundation after reinforcement to the dynamic modulus of the foundation before reinforcement, which is used to quantify the enhancement of foundation stiffness by reinforcement measures; the preset standard is a preset enhancement coefficient threshold, which is set differently according to the risk level. The enhancement coefficient threshold corresponding to the high risk level is higher than the enhancement coefficient threshold corresponding to the medium risk level; when the enhancement coefficient is lower than the preset threshold, it is determined that the reinforcement is insufficient, and supplementary reinforcement is performed for the evaluation unit. After the supplementary reinforcement, the measurement and determination are repeated until the enhancement coefficient reaches or exceeds the preset threshold.

[0014] Preferably, the transient impact load is generated by the drop hammer release. The acquisition accuracy of the dynamic vertical displacement is related to the morphological resolution of the spatial distribution curve of the deflection basin. By adjusting the radial arrangement density of each displacement sensor, the proportion of the number of sampling points in the near zone of the load center of the spatial distribution curve of the deflection basin is not less than a preset proportion, so as to ensure that the near zone with the largest curvature change of the deflection basin obtains sufficient spatial sampling density. The back-calculation result of the foundation dynamic modulus is also used to form a redundancy check with the maximum deflection parameter at the center. When the back-calculated modulus is inconsistent with the foundation stiffness trend indicated by the maximum deflection at the center, a data quality warning is triggered and a re-detection is indicated.

[0015] The present invention has achieved at least the following beneficial effects: 1. This invention divides the equipment operation area into evaluation units and binds spatial coordinates with construction load information, transforming the traditional overall reinforcement into zone identification and zone processing. Targeted reinforcement is implemented only in medium- and high-risk areas, while the original plan is maintained in low-risk areas, significantly reducing processing costs and shortening the construction period.

[0016] 2. This invention uses the dynamic response data of falling weight deflection testing as the basis for decision-making, forming a complete technical chain of testing → evaluation → reinforcement → verification, transforming traditional experience-based judgment into objective quantitative decision-making, and improving the scientific nature and controllability of foundation treatment.

[0017] 3. This invention dynamically adjusts the weights of evaluation parameters based on the load type characteristics of high-frequency impact or low-frequency static pressure equipment, so that the comprehensive risk index can highlight the dominant role of dynamic response or influence range / uniformity, avoiding systematic misjudgment by fixed-weight models in different construction scenarios.

[0018] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0019] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a flowchart illustrating the steps of a building foundation zoning reinforcement decision-making method based on falling weight deflection detection in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] like Figure 1 As shown in the figure, the method for zonal reinforcement decision-making of building foundation based on falling weight deflection detection provided by the present invention mainly includes the following steps: Step S1: Divide the construction site into multiple evaluation units according to the equipment operation area, and bind spatial coordinates and construction load information to each unit; Step S2: Apply transient impact load to each unit, collect the dynamic vertical displacement at the load center and different radial distances, and form the spatial distribution curve of the deflection basin; Step S3: Extract the maximum central deflection, deflection basin area parameters, and foundation dynamic modulus variation coefficient based on the spatial distribution curve of the deflection basin and merge them into the first type of parameters; Step S4: Integrate the first type of parameters with the construction load information into a comprehensive risk index. The integration process determines the weight allocation method of each evaluation parameter based on the load type characteristics in the construction load information. Step S5: Divide each unit into multiple risk levels based on the comprehensive risk index, and match differentiated reinforcement measures with corresponding reinforcement intensities according to the risk level; Step S6: Retest the reinforced unit, calculate the improvement coefficient based on the dynamic modulus before and after reinforcement, and determine whether it meets the preset standard.

[0022] In this embodiment, an evaluation unit refers to a basic evaluation unit obtained by dividing the construction site to be evaluated into grids according to the operating areas of the construction equipment. The operating areas of the construction equipment include the piling machine travel route area, the piling machine driving operation station area, the crane hoisting station area, the heavy transport vehicle passageway area, and the temporary material storage area. Each evaluation unit is a rectangular grid, and the grid side length is determined according to the track length or outrigger span of the construction equipment, so that the size of a single evaluation unit is related to the characteristic dimensions of the ground contact area of ​​the construction equipment. The spatial coordinates bound to each evaluation unit are the planar coordinates of the unit's center point. The bound construction load information includes equipment type and grounding pressure value. and the frequency characteristics of load action.

[0023] In this embodiment, the transient impact load is generated by the release of the falling weight of the falling weight deflectometer and is a half-sine wave impact load. Multiple displacement sensors are arranged at the load center and at different radial distances from the load center to simultaneously acquire the vertical displacement response in both the near and far regions of the load center. The radial spacing between the sensors is smaller near the load center than far from it to obtain higher sampling resolution in the near region where the curvature of the deflection basin changes most. After extracting the peak displacement values ​​at each measuring point, the spatial distribution curve of the deflection basin for this evaluation unit is formed. ,in The radial distance from the center of the load. Number the evaluation unit.

[0024] In this embodiment, the maximum central deflection is taken as the peak displacement at the center of the load. This parameter is used to characterize the overall stiffness of the foundation. The deflection basin area parameter is obtained by integrating the spatial distribution curve of the deflection basin over the radial distance. ,in The placement distance of the farthest displacement sensor (usually taken as...) The dynamic modulus of foundation is used to characterize the spatial extent of load influence in the foundation. The coefficient of variation of the dynamic modulus of the foundation is obtained by back-calculation based on the theory of elastic layered systems; the specific formula is described later. ,in Obtained from multiple tests within the same evaluation unit standard deviation Its average value is used to characterize the spatial uniformity of the foundation.

[0025] In this embodiment, the first type of parameters (including) , , ) and construction load information (including (Integrated into a comprehensive risk index) At that time, each evaluation parameter is normalized to a unified dimension and then combined using a weighted summation method: in, The preset reference maximum deflection threshold (unit: ), The preset reference deflection basin area threshold (unit: ), The preset reference grounding pressure value (unit: ), weighting coefficient satisfy Furthermore, it is determined based on the load type of the construction equipment—when the construction equipment is a hammer-type device that generates high-frequency impact loads, the load is increased. and The value of ; when the construction equipment is a static pressure type equipment that generates low-frequency static pressure load, increase . and The value of .

[0026] In this embodiment, the risk levels include low risk, medium risk, and high risk. A first risk threshold is preset. Second risk threshold Multiple risk thresholds, including .when When it is classified as a low-risk level, When it was designated as a medium-risk level, The risk level is designated as high. Low-risk levels are assigned no additional reinforcement measures and construction is carried out according to the original construction plan; medium-risk levels are assigned the first type of reinforcement measures; high-risk levels are assigned the second type of reinforcement measures, with the reinforcement strength of the second type of reinforcement measures being higher than that of the first type of reinforcement measures.

[0027] In this embodiment, the lifting factor is the dynamic modulus of the reinforced foundation. Dynamic modulus of foundation before reinforcement The ratio is denoted as This is used to quantify the increase in foundation stiffness caused by reinforcement measures. The preset standard is a preset threshold for the increase coefficient. ,when When the reinforcement is deemed qualified, If the reinforcement is deemed insufficient, supplementary reinforcement will be carried out. Based on risk level differentiation, the high-risk level corresponds to... Higher than the corresponding medium risk level .

[0028] The beneficial effects of the above technical solutions are as follows: Spatial differentiation evaluation of foundation performance over large areas is achieved through gridding and spatial coordinate binding; dynamic response characteristics of the foundation under simulated construction loads are obtained through deflection basin detection under transient impact loads; foundation performance is characterized from three dimensions—stiffness, influence range, and uniformity—by extracting the maximum central deflection, deflection basin area, and dynamic modulus variation coefficient; a comprehensive risk index is constructed through dynamic weight fusion, enabling the evaluation model to adapt to different equipment, including impact-type and static-pressure-type equipment; precise reinforcement is achieved through three-level risk classification and differentiated reinforcement matching; and closed-loop quality control is formed through retesting and enhancement coefficient verification.

[0029] In a preferred embodiment, the evaluation unit is divided as follows: the grid side length of the evaluation unit is determined according to the track length or outrigger span of the construction equipment, so that the size of a single evaluation unit is associated with the characteristic size of the ground contact area of ​​the construction equipment; wherein, the construction equipment operation area includes at least one of the following: the pile driver travel route area, the pile driver pile driving operation station area, the crane hoisting station area, the heavy transport vehicle passage road area, and the temporary material storage area; the construction load information includes equipment type, ground pressure value, and load frequency characteristics. When there are multiple construction equipment in the same evaluation unit, the load value corresponding to the most unfavorable load condition is taken.

[0030] In this embodiment, the track length of the construction equipment is... (unit: ), outrigger span is (unit: ), grid side length Take as to A specific value between these ranges. For example, the track length of a static pile driver. outrigger span ,but Grid side length Desirable In this embodiment, we take The grid side length is related to the equipment grounding size, which ensures that the ground area covered by a single grid cell can reflect the average performance of the entire equipment grounding area, avoiding the introduction of unnecessary local noise due to an overly fine grid, or the masking of local weak zones due to an overly coarse grid.

[0031] In this embodiment, the equipment type in the construction load information is used to determine whether it is impact-type or static-type, and the grounding pressure value. Calculated based on the equipment's own weight and grounding area. For example, the equipment's own weight... (unit: Track ground contact area (unit: ),but (unit: When multiple devices reside within the same memory unit, take... This refers to the most unfavorable load condition. The load frequency characteristics are used for subsequent weighting coefficient adjustments. For impact loads (such as diesel hammers), the impact frequency is approximately... If it is a high-frequency impact type, then it is determined to be a static pressure type (pile driving speed approximately...). If the value is 0, it is identified as a low-frequency static pressure type.

[0032] In this embodiment, the construction equipment operating area is identified through the overall construction layout plan, including the pile driver's travel route (moving load), pile driving station (stationary load), crane station (concentrated load), heavy vehicle road (moving heavy load), and storage yard (continuous static load). All these areas are included in the evaluation unit to ensure that all locations where foundation risks may occur are covered.

[0033] In a preferred embodiment, the spatial distribution curve of the deflection basin is formed as follows: multiple displacement sensors are arranged at the load center and at different radial distances from the load center to simultaneously acquire the vertical displacement response in the near and far regions of the load center. The radial spacing of each sensor is smaller near the load center than far from the load center to obtain higher sampling resolution in the near region where the curvature of the deflection basin changes the most. Each evaluation unit performs multiple independent tests and takes the arithmetic mean of the test results as the spatial distribution curve of the deflection basin for that evaluation unit. During the test, the ambient temperature and surface moisture content are recorded simultaneously. When the ambient temperature exceeds the preset temperature range or the surface moisture content exceeds the preset moisture content range, the obtained data is corrected for temperature and moisture content.

[0034] In this embodiment, the number of displacement sensors Pick or One. With For example, the measuring points are arranged radially on the same side of the load center, and the distance of each measuring point from the center is... ( The following are respectively: , , , , , , The furthest distance It can also be extended to ,Increase , Two measuring points, but the near area ( The sampling point density in the near region is still higher than in the far region. This unequal spacing arrangement allows the deflection basin curve to have more sampling points in the near region (where curvature changes greatly), ensuring integration. The accuracy can be improved. In practical calculations, compound Simpson integrals or spline interpolation can be used.

[0035] In this embodiment, each evaluation unit performs... Secondary independent detection, usually The interval between each test should be at least... This is to ensure that the instantaneous deformation of the foundation surface under impact load is completely recovered. The arithmetic mean of the results: in For the first The deflection basin curve of the second test. By averaging, random effects such as drop hammer release angle deviation, sensor installation error, and local surface undulations can be eliminated.

[0036] In this embodiment, the ambient temperature The preset range is Surface volumetric water content The preset range is Record simultaneously during detection. and If the values ​​exceed the above range, corrections will be made. The correction method is as follows: Select a reference point within the site beforehand, and apply the values ​​at different temperatures (e.g., ...). , , , ) and different moisture contents (e.g. , , Calibration experiments were conducted under these conditions to establish a piecewise linear correction function. Temperature correction function. for: Moisture content correction function for: in, Standard temperature Standard moisture content, , , The slope coefficient, determined through calibration tests, is not a fixed empirical constant, but a site-specific value determined based on calibration tests conducted on the actual soil of the project site. The specific process of the calibration tests is as follows: A representative reference area with consistent soil conditions and stable foundation performance, consistent with the soil of the unit to be evaluated, is selected within the construction site. Falling-weighted deflection tests are conducted under different ambient temperature conditions and different surface moisture contents. Using the deflection basin benchmark value measured under a preset standard state (temperature T0 = 20°C, moisture content w0 = 15%) as a reference, the measured correction factor for each deviation state is calculated. Subsequently, using the temperature difference (Tamb - T0) or moisture content difference (w - w0) as the independent variable and the measured correction factor as the dependent variable, a univariate linear regression is performed using the least squares method. The absolute value of the slope of the straight line obtained from the regression fitting is determined as the slope coefficient for the low-temperature zone. Slope coefficient in high-temperature region and moisture content slope coefficient Through the above calibration, the temperature correction function can be adjusted. and moisture content correction function To accurately reflect the true sensitivity of the foundation's dynamic response to environmental and humidity changes under specific soil conditions at this site, avoiding over- or under-correction due to the use of general empirical values, and ensuring that the corrected deflection data matches the actual site conditions. For example, site determination of cohesive soil... (This means that in the low-temperature range, the deflection correction changes by 0.8% for every 1°C change in temperature.) (This means that in the high-temperature range, the deflection correction changes by 0.12% for every 1°C change in temperature.) (This means that for every 1% change in moisture content, the deflection correction changes by 2.5%). The correction formula is: Among them, when At that time, the soil hardens and the deflection is smaller. ;when At that time, the soil softens and deflection is excessive. ;when At that time, the soil modulus decreased and the deflection was excessive. Specific calibration values ​​can be obtained through on-site comparative tests.

[0037] In a preferred embodiment, the first type of parameter is extracted as follows: the maximum central deflection is taken as the peak displacement at the center of the load, which is used to characterize the overall stiffness of the foundation; the deflection basin area parameter is obtained by integrating the spatial distribution curve of the deflection basin over the radial distance, which is used to characterize the spatial influence range of the load in the foundation; the foundation dynamic modulus is calculated based on the elastic layered system theory, according to the peak displacement at the center of the load, the peak value of the impact load, and the geometric dimensions of the bearing plate, wherein a correction coefficient is applied to the calculation result according to the foundation soil type to eliminate the deviation between the theoretical assumption and the actual soil response; the coefficient of variation of the foundation dynamic modulus is the ratio of the standard deviation to the average value of multiple foundation dynamic modulus data obtained from multiple tests within the same evaluation unit, which is used to characterize the spatial uniformity of the foundation.

[0038] In this embodiment, the maximum central deflection Directly read the peak displacement of the sensor at the center of the load, in units of... .

[0039] Deflection basin area parameters ,because For discrete sampling, numerical integration is used. If unequal interval sampling is used, then first... Perform cubic spline interpolation, and then apply Simpson's rule on the equally spaced grid, or directly use the composite trapezoidal rule. The unit is Its physical meaning is the total range of load influence. The larger the value, the thicker the weak foundation layer or the lower the stiffness, and the wider the range of influence.

[0040] dynamic modulus of foundation Based on the theory of elastic layered systems (Boussinesq solution or multilayer elasticity theory), the commonly used formula is: in: Peak impact load (unit: The drop weight is determined by the mass and height of the drop, for example... ; Radius of the bearing plate (unit: ), usually ; The Poisson's ratio for the foundation is determined based on the soil type: for cohesive soil, the value is [value missing]. , sandy soil gravel and soil ; This is the deflection correction factor, reflecting the difference between the theoretical assumption (homogeneous elastic half-space) and the actual layered soil. Its value range is [value range missing]. : clay soil , sandy soil gravel and soil Correction factor The smaller the value, the greater the deviation between the actual soil and the theoretical homogeneous assumption, and the lower the calculated modulus.

[0041] coefficient of variation of foundation dynamic modulus Specifically, within the same evaluation unit... Each test yields a result after inverse calculation. ( ),but It is a dimensionless number, usually between between. The smaller the value, the more uniform the foundation. The larger the value, the more significant the spatial variability of the foundation.

[0042] In a preferred embodiment, the risk comprehensive index is integrated as follows: each evaluation parameter is normalized to a unified dimension and then combined into a comprehensive index by weighted summation. The weighting coefficients used in the weighted summation are determined according to the load type of the construction equipment. When the construction equipment is a hammer-type equipment that generates high-frequency impact loads, the weights of the maximum central deflection parameter and construction load information are increased to highlight the dominant role of dynamic response and load amplitude. When the construction equipment is a static pressure type equipment that generates low-frequency static pressure loads, the weights of the deflection basin area parameter and the coefficient of variation of the foundation dynamic modulus are increased to highlight the dominant role of the load influence range and foundation uniformity. The weighting coefficients are determined by a multi-criteria decision analysis method.

[0043] In this embodiment, the comprehensive risk index The calculation model is as follows: in, , , This is a regional empirical benchmark or design allowable value. For example, for a site backfilled with cohesive soil, it can be taken as... , , . For the weighting coefficients, satisfying .

[0044] The weighting coefficients were determined using the Analytic Hierarchy Process (AHP). Four evaluation parameters ( , , , As a criterion, it is determined by at least Geotechnical experts conducted pairwise comparisons based on their engineering experience (Saaty) (Scale). Regarding hammer-type equipment, experts believe that... and More importantly, construct the judgment matrix. The following is an example (using one of the experts): The order of rows and columns is as follows: , , , By solving for the largest eigenvalue of the matrix. and the corresponding normalized feature vector The weighting coefficients are obtained. After calculation, Consistency ratio This satisfies the consistency requirement. The normalized feature vector is the weight vector, for example: Right now , , , .

[0045] Regarding static pressure equipment, experts believe that and More importantly, construct the judgment matrix. as follows: Calculations show that , The normalized eigenvectors are: Right now , , , For other operating conditions (such as those involving both impact and static pressure), adjustments can be made based on weighted averages or further refined rules.

[0046] In this embodiment, normalization ensures that the dimensions of each component are consistent, preventing any one component from dominating due to differences in numerical ranges. For example, if exist Change, divided by Later became ; exist Change, divided by Later became ; exist Change itself is dimensionless; exist Change, divided by Later became This ensures that the components are roughly of the same order of magnitude, guaranteeing the rationality of the weighted summation.

[0047] In a preferred embodiment, the method further includes: calling a theoretical deflection basin morphology template corresponding to the load action mechanism characteristics reflected by the currently determined weighting coefficients; substituting the foundation dynamic modulus and the maximum central deflection of the evaluation unit into the theoretical deflection basin morphology template to generate a desired deflection basin spatial distribution curve adapted to the mechanical parameters of the evaluation unit; comparing the desired deflection basin spatial distribution curve with the actual detected deflection basin spatial distribution curve in three dimensions: deflection basin depth characteristics, deflection basin width characteristics, and deflection basin curvature attenuation characteristics, and calculating the depth deviation component, width deviation component, and curvature deviation component respectively; and identifying the deviation source type based on the relative magnitude relationship of the depth deviation component, width deviation component, and curvature deviation component. When the depth deviation component dominates while the width and curvature deviation components are within the normal range, the detection data is deemed abnormal, triggering a re-detection instruction. When either the width or curvature deviation component dominates while the depth deviation component is within the normal range, the load type characteristics are deemed mismatched with the actual load response mechanism of the evaluation unit, triggering a weight configuration anomaly warning and instructing a re-verification of the load type characteristics. When all three deviation components exceed the normal range, the evaluation unit is deemed to have a hidden geological anomaly that does not conform to the current weight configuration's stratigraphic structure assumptions, triggering a supplementary exploration instruction. The depth deviation component, width deviation component, and curvature deviation component are weighted and fused according to the sensitivity coefficients corresponding to the weights of each evaluation parameter in the weight coefficients to obtain the morphological deviation index.

[0048] In this embodiment, the theoretical deflection basin morphology template library contains two types of templates. The templates are obtained through theoretical solutions of elastic half-space or regression analysis using a large amount of measured data, and their mathematical forms are as follows: For static pressure loads (approximately static loading), the normalized deflection basin function based on the elastic half-space Boussinesq solution is used as a template: in, To the radius of the bearing plate Characteristic lengths related to soil properties , These are dimensionless characteristic coefficients, determined by field calibration or finite element numerical simulation regression, and typically take values ​​of [value missing]. The evaluation unit and Substituting the values, we obtain the desired deflection basin: For hammer-type loads (half-sine pulses, short duration), a dynamic solution template considering stress wave propagation is used: in, The characteristic width parameter, related to the stress wave spread angle and soil damping, is determined by statistical regression from site-measured data or calibration using finite element numerical simulation. The evaluation unit's... and Substituting the values, we obtain the desired deflection basin: For the current evaluation unit, it is... and Substituting the corresponding template, we obtain the desired deflection basin. The measured deflection basin is... The three deviation components are defined as follows: 1. Depth deviation component : Reflects the relative difference in peak deflection 2. Width deviation component Define halfwidth To reduce deflection to its peak value The radial distance at that time, 3. Curvature attenuation deviation component Define the dimensionless curvature integral. ,but Normal range preset: , , .

[0049] Judgment rules: like and , If the test data is abnormal (e.g., the drop hammer is unbalanced), a retest will be triggered.

[0050] like or ,and If the load type template does not match the actual load (e.g., the actual equipment is static pressure, but the template uses impact type), an abnormal weight configuration warning will be triggered.

[0051] If all three deviation components are greater than If so, it is determined that there is a hidden geological anomaly (such as a sudden appearance of a thick layer of soft soil), triggering supplementary exploration.

[0052] Morphological deviation index The result is a weighted fusion of the three deviation components using sensitivity coefficients, which correspond to the weighting coefficients in the risk composite index. in, , , These are sensitivity coefficients, corresponding to the weighting coefficients for maximum central deflection, deflection basin area, and foundation uniformity, respectively. For example, for hammer-type equipment, take... , , For static pressure equipment, take , , Morphological deviation index As an independent indicator, it is used to assist in judging data quality, the rationality of weight allocation, and stratigraphic anomalies, and is not included in the comprehensive risk index. The calculation.

[0053] In a preferred embodiment, the risk level is divided as follows: multiple risk thresholds are preset, including a first risk threshold and a second risk threshold, wherein the first risk threshold is lower than the second risk threshold; when the comprehensive risk index of the evaluation unit does not exceed the first risk threshold, it is classified as a low-risk level; when the comprehensive risk index exceeds the first risk threshold but does not exceed the second risk threshold, it is classified as a medium-risk level; and when the comprehensive risk index exceeds the second risk threshold, it is classified as a high-risk level. The first and second risk thresholds are obtained by calibrating the comprehensive risk index of a reference evaluation unit with known good foundation performance and a reference evaluation unit with known poor foundation performance in the same construction site, so that the risk thresholds are adaptively matched with the actual geological conditions and foundation performance level of the site.

[0054] In this embodiment, at least... A known good-performing reference unit (such as a natural hard soil outcrop area) and at least Consider a reference unit with known poor performance (e.g., an area that has already subsided). Calculate its risk index for each. and .make Then multiply by a safety factor: in Pick (usually taken) ), Pick (usually taken) For example, if ,but ;like ,but This division ensures that the low-risk area is slightly smaller than the known good area, and the high-risk area is slightly larger than the known bad area, reflecting a design biased towards safety.

[0055] In a preferred embodiment, the differentiated reinforcement measures are matched as follows: low-risk levels are matched with no additional reinforcement measures and construction is organized according to the original construction plan; medium-risk levels are matched with the first type of reinforcement measures, which include at least one of laying steel plates to spread the load, laying crushed stone cushion layers to improve bearing capacity, or implementing compaction treatment to improve surface density; high-risk levels are matched with the second type of reinforcement measures, which have a higher reinforcement strength than the first type of reinforcement measures. The second type of reinforcement measures include at least one of the following: replacement treatment by excavating and backfilling and compacting the weak soil layer, grouting reinforcement by injecting cementitious materials into the foundation, or composite foundation treatment by forming reinforcement bodies in the foundation; wherein, the thickness of the steel plate or the thickness of the crushed stone cushion layer in the first type of reinforcement measures are determined according to the extent to which the comprehensive risk index of the evaluation unit exceeds the lower limit threshold of the medium-risk level.

[0056] In this embodiment, for the medium-risk level, let... Two preset difference thresholds are used. , .

[0057] like Lay a single layer of steel plate, thickness ; like Lay a gravel bedding layer, thickness compaction degree ; like Then the combination of steel plate + crushed stone bedding layer (steel plate) + gravel ).

[0058] For high-risk levels, set Preset , .

[0059] like Replacement treatment, replacement depth ; like Grouting reinforcement, grouting pressure water-cement ratio Hole spacing ; like Mixing pile composite foundation, pile diameter Pile spacing The pile length penetrates the weak layer.

[0060] All reinforcement parameters (thickness, pressure, pile diameter, etc.) can be fine-tuned based on the actual survey report, but the adjustment range should not exceed the above values. .

[0061] In a preferred embodiment, the improvement coefficient is calculated and determined as follows: the improvement coefficient is the ratio of the dynamic modulus of the foundation after reinforcement to the dynamic modulus of the foundation before reinforcement, which is used to quantify the improvement of foundation stiffness by reinforcement measures; the preset standard is a preset improvement coefficient threshold, which is set differently according to the risk level, with the improvement coefficient threshold corresponding to the high-risk level being higher than that corresponding to the medium-risk level; when the improvement coefficient is lower than the preset threshold, it is determined that the reinforcement is insufficient, and supplementary reinforcement processing is performed for the evaluation unit, and the measurement and determination are repeated after the supplementary reinforcement processing until the improvement coefficient reaches or exceeds the preset threshold.

[0062] In this embodiment, after reinforcement is completed, FWD (Focused Dynamic Modulus) is re-measured on medium- and high-risk units to obtain the dynamic modulus after reinforcement. Improvement coefficient Medium-risk level preset. High-risk level preset .

[0063] like If necessary, supplementary reinforcement should be implemented. For example, if the original foundation was a crushed stone cushion layer, the number of compaction passes should be increased or an additional steel plate should be laid; if the foundation was grouting, the grouting pressure should be increased or the grouting holes should be densified; if the foundation was a mixing pile, the number of piles should be increased or the pile spacing should be decreased. After supplementary reinforcement, the results should be remeasured and recalculated. until satisfied .

[0064] In this embodiment, all remeasurement data, reinforcement parameters, and lifting coefficients are entered into a database for reference in subsequent similar projects. Simultaneously, based on the spatial coordinates of each unit... A risk distribution map is generated based on the risk level, with different colors used to distinguish low, medium, and high risk areas, to help construction workers plan their routes and work sequences.

[0065] In a preferred embodiment, the transient impact load is generated by the release of the drop hammer. The acquisition accuracy of the dynamic vertical displacement is related to the morphological resolution of the spatial distribution curve of the deflection basin. By adjusting the radial arrangement density of each displacement sensor, the proportion of the number of sampling points in the near zone of the load center of the spatial distribution curve of the deflection basin is not less than a preset proportion, so as to ensure that the near zone with the largest curvature change of the deflection basin obtains sufficient spatial sampling density. The back-calculation result of the foundation dynamic modulus is also used to form a redundancy check with the maximum deflection parameter at the center. When the back-calculated modulus is inconsistent with the foundation stiffness trend indicated by the maximum deflection at the center, a data quality warning is triggered and a re-detection is indicated.

[0066] In this embodiment, the preset ratio Define the near zone as .For example, Then the near-zone boundary is If arranged One sensor, of which One in Within (e.g.) , , , , Then the sampling ratio of the near area The requirements are met.

[0067] Redundancy check: due to Theoretically The larger, The smaller. If it appears large and Significant (or conversely) inconsistencies indicate potential data anomalies at that detection point. The system will issue a warning and suggest re-detecting the unit. Additionally, an allowable deviation range can be set based on historical data, for example... It should be within a certain range; if it exceeds this range, a warning will be triggered.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection, characterized in that, include: The construction site is divided into multiple evaluation units according to the equipment operation area, and each unit is bound to spatial coordinates and construction load information. Transient impact loads are applied to each unit, and dynamic vertical displacements at the load center and different radial distances are collected to form the spatial distribution curve of the deflection basin. Based on the spatial distribution curve of the deflection basin, the maximum central deflection, the area parameters of the deflection basin, and the coefficient of variation of the dynamic modulus of the foundation are extracted and combined into the first type of parameters. The first type of parameters are integrated with the construction load information to form a comprehensive risk index. The integration process determines the weight allocation method of each evaluation parameter based on the load type characteristics in the construction load information. Based on the comprehensive risk index, each unit is divided into multiple risk levels, and differentiated reinforcement measures with corresponding reinforcement strengths are matched according to the risk level. The reinforced units are retested, and the improvement coefficient is calculated based on the dynamic modulus before and after reinforcement to determine whether the preset standard is met.

2. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The evaluation unit is divided as follows: the grid side length of the evaluation unit is determined according to the track length or outrigger span of the construction equipment, so that the size of a single evaluation unit is related to the characteristic size of the ground contact area of ​​the construction equipment; wherein, the construction equipment operation area includes at least one of the following: the pile driver travel route area, the pile driver pile driving operation station area, the crane hoisting station area, the heavy transport vehicle passage road area, and the temporary material storage area; the construction load information includes equipment type, ground pressure value, and load frequency characteristics. When there are multiple construction equipment in the same evaluation unit, the load value corresponding to the most unfavorable load condition is taken.

3. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The spatial distribution curve of the deflection basin is formed as follows: multiple displacement sensors are arranged at the load center and at different radial distances from the load center to simultaneously acquire the vertical displacement response in the near and far regions of the load center. The radial spacing of each sensor is smaller near the load center than far from the load center to obtain higher sampling resolution in the near region where the curvature of the deflection basin changes the most. Each evaluation unit performs multiple independent tests and takes the arithmetic mean of the test results as the spatial distribution curve of the deflection basin for that evaluation unit. During the test, the ambient temperature and surface moisture content are recorded simultaneously. When the ambient temperature exceeds the preset temperature range or the surface moisture content exceeds the preset moisture content range, the obtained data is corrected for temperature and moisture content.

4. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The extraction method for the first type of parameters is as follows: the maximum central deflection is taken as the peak displacement at the center of the load, which is used to characterize the overall stiffness of the foundation; the deflection basin area parameter is obtained by integrating the spatial distribution curve of the deflection basin over the radial distance, which is used to characterize the spatial influence range of the load in the foundation; the dynamic modulus of the foundation is calculated based on the theory of elastic layered systems, according to the peak displacement at the center of the load, the peak value of the impact load, and the geometric dimensions of the bearing plate. A correction coefficient is applied to the back-calculation results according to the type of foundation soil to eliminate the deviation between theoretical assumptions and actual soil response. The coefficient of variation of the dynamic modulus of the foundation is the ratio of the standard deviation to the mean of multiple dynamic modulus data of the foundation obtained from multiple tests within the same evaluation unit, and is used to characterize the spatial uniformity of the foundation.

5. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 2, characterized in that, The integration method of the comprehensive risk index is as follows: each evaluation parameter is normalized to a unified dimension and then combined into a comprehensive index by weighted summation. The weighting coefficients used in the weighted summation are determined according to the load type of the construction equipment. When the construction equipment is a hammer-type equipment that generates high-frequency impact loads, the weights of the maximum central deflection parameter and construction load information are increased to highlight the dominant role of dynamic response and load amplitude. When the construction equipment is a static pressure type equipment that generates low-frequency static pressure loads, the weights of the deflection basin area parameter and the coefficient of variation of the foundation dynamic modulus are increased to highlight the dominant role of the load influence range and foundation uniformity. The weighting coefficients are determined by a multi-criteria decision analysis method.

6. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 5, characterized in that, Also includes: Based on the load action mechanism characteristics reflected by the currently determined weight coefficients, the theoretical deflection basin shape template corresponding to the load action mechanism characteristics is called; the foundation dynamic modulus and the maximum central deflection of the evaluation unit are substituted into the theoretical deflection basin shape template to generate the expected deflection basin spatial distribution curve that is adapted to the mechanical parameters of the evaluation unit. The expected spatial distribution curve of the deflection basin is compared with the actual spatial distribution curve of the deflection basin in three dimensions: deflection basin depth characteristics, deflection basin width characteristics, and deflection basin curvature attenuation characteristics. The depth deviation component, width deviation component, and curvature deviation component are calculated respectively. The source of deviation is identified based on the relative magnitude of the depth deviation component, width deviation component, and curvature deviation component: when the depth deviation component is dominant and the width deviation component and curvature deviation component are within the normal range, the detection data is determined to be abnormal, triggering a re-detection instruction; when the width deviation component or curvature deviation component is dominant and the depth deviation component is within the normal range, the load type characteristics are determined to be mismatched with the actual load response mechanism of the evaluation unit, triggering a weight configuration anomaly warning and instructing a re-verification of the load type characteristics. When all three deviation components exceed the normal range, it is determined that the evaluation unit has a hidden geological anomaly that does not conform to the stratigraphic structure assumption corresponding to the current weight configuration, triggering a supplementary exploration instruction. The depth deviation component, width deviation component, and curvature deviation component are weighted and fused according to the sensitivity coefficients corresponding to the weights of each evaluation parameter in the weighting coefficient to obtain the morphological deviation index.

7. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The risk level is divided as follows: multiple risk thresholds are preset, including a first risk threshold and a second risk threshold, wherein the first risk threshold is lower than the second risk threshold; when the comprehensive risk index of the evaluation unit does not exceed the first risk threshold, it is classified as a low risk level; when the comprehensive risk index exceeds the first risk threshold but does not exceed the second risk threshold, it is classified as a medium risk level; when the comprehensive risk index exceeds the second risk threshold, it is classified as a high risk level. The first and second risk thresholds are obtained by calibrating the comprehensive risk index of reference evaluation units with known good foundation performance and reference evaluation units with known poor foundation performance in the same construction site, so that the risk thresholds are adaptively matched with the actual geological conditions and foundation performance level of the site.

8. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The differentiated reinforcement measures are matched as follows: low-risk levels are matched with no additional reinforcement measures and construction is organized according to the original construction plan; medium-risk levels are matched with the first type of reinforcement measures, which include at least one of the following: laying steel plates to spread the load, laying crushed stone cushion layers to improve bearing capacity, or implementing compaction treatment to improve surface density; high-risk levels are matched with the second type of reinforcement measures, which have a higher reinforcement strength than the first type of reinforcement measures. The second type of reinforcement measures include at least one of the following: replacement treatment by excavating and backfilling and compacting the weak soil layer, grouting reinforcement by injecting cementing materials into the foundation, or composite foundation treatment to form reinforcement bodies in the foundation; wherein, the thickness of the steel plate or the thickness of the crushed stone cushion layer in the first type of reinforcement measures are determined according to the extent to which the comprehensive risk index of the evaluation unit exceeds the lower limit threshold of the medium-risk level.

9. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The method for calculating and determining the lifting coefficient is as follows: the lifting coefficient is the ratio of the dynamic modulus of the foundation after reinforcement to the dynamic modulus of the foundation before reinforcement, which is used to quantify the extent to which the reinforcement measures improve the stiffness of the foundation. The preset standard is a preset enhancement coefficient threshold. The enhancement coefficient threshold is set differently according to the risk level. The enhancement coefficient threshold corresponding to the high risk level is higher than that corresponding to the medium risk level. When the enhancement coefficient is lower than the preset threshold, it is judged as insufficient reinforcement. Supplementary reinforcement is performed for the evaluation unit. After the supplementary reinforcement, the evaluation is repeated until the enhancement coefficient reaches or exceeds the preset threshold.

10. The method for decision-making on zonal reinforcement of building foundations based on falling weight deflection detection according to claim 1, characterized in that, The transient impact load is generated by the release of the drop hammer. The acquisition accuracy of the dynamic vertical displacement is related to the morphological resolution of the spatial distribution curve of the deflection basin. By adjusting the radial arrangement density of each displacement sensor, the proportion of the number of sampling points in the near zone of the load center of the spatial distribution curve of the deflection basin is not less than the preset proportion, so as to ensure that the near zone with the largest curvature change of the deflection basin obtains sufficient spatial sampling density. The back calculation result of the foundation dynamic modulus is also used to form a redundancy check with the maximum deflection parameter at the center. When the back calculation modulus is inconsistent with the foundation stiffness trend indicated by the maximum deflection at the center, a data quality warning is triggered and a re-detection is indicated.

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