A comprehensive detection and evaluation method for construction quality of a foundation pit backfill area

Abstract

The present application relates to the field of foundation pit engineering construction, and particularly relates to a comprehensive detection and evaluation method for construction quality of a backfill area of a foundation pit, which introduces an undisturbed area as a comparison, and through the cooperative detection of multiple indexes of soil body settlement deformation, soil body shear strength, soil body specific gravity and soil body density, calculates the average difference rate, difference rate jump value and influence coefficient of the modified evaluation index and comprehensive evaluation index of multiple positions of the backfill area respectively, and finally constructs the comprehensive evaluation index to evaluate the construction quality of the backfill area. Through the multiple depth detection comparison, the change and influence degree of the backfill area construction on the original state of the soil body are accurately quantified, which can provide scientific and accurate basis for the quality control of the backfill of the foundation pit, fundamentally improves the quality control level of the foundation pit engineering, and effectively guarantees the long-term safe and stable operation of the subsequent engineering.

Description

Technical Field

[0001] This invention relates to the field of foundation pit construction, and specifically to a comprehensive testing and evaluation method for the construction quality of the backfill area of ​​a foundation pit. Background Technology

[0002] In urban construction and infrastructure projects, foundation pit backfilling is a crucial preliminary step in underground structure construction, and its quality directly affects the safety and long-term stability of subsequent projects. From an engineering safety perspective, substandard backfilling can lead to uneven settlement of subsequent buildings, wall cracking, foundation tilting, and even jeopardize structural stability. In municipal pipeline projects, inadequate backfilling can cause pipeline compression deformation, damage, and breakage, thus affecting the normal operation of urban functions. However, existing methods for inspecting the construction quality of foundation pit backfill areas have shortcomings, specifically in the following aspects:

[0003] 1) Traditional quality inspection of foundation pit backfill often relies on a single indicator, such as only testing compaction degree, which cannot comprehensively reflect the overall quality of backfill soil at different strata depths, including mechanical properties and deformation characteristics. Soil at different strata depths is affected by construction disturbances and differences in geological conditions, resulting in complex and diverse quality performance. Single-indicator testing is prone to missing key issues and is difficult to meet the needs of refined project management.

[0004] 2) Existing testing and evaluation methods lack a systematic comparison between backfilled areas and undisturbed areas. Soil indicators in undisturbed areas are an important reference for judging whether backfill quality is up to standard. Ignoring this comparison will cause the quality evaluation to lose its "benchmark" and make it impossible to accurately quantify the changes and impacts of backfilling construction on the original state of the soil.

[0005] 3) In terms of quality grade, the evaluation did not fully consider the later use of the backfill area and the importance of the project, which limited the guiding value of the evaluation results for engineering practice and could not provide a basis for quality judgment for different types of projects.

[0006] 4) Lack of targeted remedial solutions. Existing methods only focus on quality assessment and do not provide corresponding remedial measures for different levels. The test results are disconnected from subsequent quality improvement work, making it difficult to quickly and efficiently resolve backfill quality issues. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a comprehensive testing and evaluation method for the construction quality of the backfill area of ​​a foundation pit, which fills a technological gap and ensures the safety and reliability of the foundation pit and subsequent projects.

[0008] The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit, as described in this invention, specifically includes the following steps:

[0009] S1: Testing of various indicators at a certain depth below a certain location on the ground surface of the backfill area; these indicators include soil settlement deformation, soil shear strength, soil weight, and soil density.

[0010] S2: Detection of various indicators at a certain depth below a certain location on the ground in the undisturbed area; the height of a certain depth location in the undisturbed area from the ground is the same as that of a certain depth location in the backfilled area;

[0011] S3: Based on the detection values ​​of each indicator in S1 and S2, establish a difference rate index for a certain depth location at a certain location in the backfill area;

[0012] S4: Set a depth position at regular intervals at a certain location on the ground in both the backfilled area and the undisturbed area, and establish the difference rate index of different depth positions at a certain location in the backfilled area according to steps S1-S3.

[0013] S5: Calculate the average difference rate and the difference rate jump value at a certain depth location in the backfill area based on the difference rate index at different depth locations.

[0014] S6: Take L locations on the ground in the backfill area, and calculate the average difference rate and the difference rate jump value of the L locations according to steps S1-S5 respectively;

[0015] S7: Calculate the corrected evaluation index for each of the L locations in the backfill area based on the average difference rate and the jump value of the difference rate.

[0016] S8: Calculate the influence coefficient of the comprehensive evaluation index based on the modified evaluation indexes of L positions;

[0017] S9: Based on the influence coefficients of the modified evaluation index and the comprehensive evaluation index, construct a comprehensive evaluation index for the construction quality of the backfill area, and set an allowable value for the construction quality evaluation index of the backfill area. When the comprehensive evaluation index value is less than the allowable value for the construction quality evaluation index of the backfill area, it is determined that the construction quality of the foundation pit backfill area meets the requirements; when the comprehensive evaluation index value is greater than or equal to the allowable value for the construction quality evaluation index of the backfill area, it is determined that the construction quality of the foundation pit backfill area does not meet the requirements.

[0018] As a further step, the following steps are also included:

[0019] S10: Based on comprehensive evaluation indicators, combined with the later use of the backfill area and the importance of the project, the construction quality comprehensive inspection and evaluation level is classified.

[0020] S11: Based on the classification level, take remedial measures to improve the construction quality level of the backfill area.

[0021] Furthermore,

[0022] In steps S1 and S2, soil settlement deformation is measured using leveling or sensor monitoring, soil shear strength is measured using vane shear test, soil weight is measured using ring cutter method, and soil compaction is measured using ring cutter method for cohesive soil and sand cone method for granular soil.

[0023] The difference rate indices at a certain depth of a certain location in the backfill area in step S3 are as follows:

[0024] The soil settlement deformation difference rate index at a certain depth in the backfill area , ;

[0025] Soil shear strength difference rate at a certain depth in the backfill area : ;

[0026] The soil weight difference rate at a certain depth in the backfill area : ;

[0027] Soil density difference rate at a certain depth in the backfill area : ;

[0028] Where s represents the soil settlement deformation in the backfill area of ​​the foundation pit; The shear strength of the soil in the backfill area of ​​the foundation pit; The weight of the soil in the backfill area of ​​the foundation pit; The soil compaction density in the backfill area of ​​the foundation pit; For soil settlement and deformation in undisturbed areas, For the soil shear strength in the undisturbed area, For the soil weight in the undisturbed area, This refers to the soil density in the undisturbed area.

[0029] In step S4, the backfill area and the undisturbed area are respectively set up depth position , The difference rate indices at different depths downward from a certain location in the backfill area are as follows:

[0030] The index of soil settlement and deformation difference rate at different depths in the backfill area is:

[0031] ;

[0032] The soil shear strength difference rate index at different depths in the backfill area is as follows:

[0033] ;

[0034] The soil weight difference rate index at different depths in the backfill area is as follows:

[0035] ;

[0036] The soil compaction difference rate index at different depths in the backfill area is as follows:

[0037] .

[0038] In step S5, the average difference rate and the difference rate jump value at a certain location in the backfill area are respectively:

[0039] The average difference rate of soil settlement deformation at a certain location in the backfill area is:

[0040] ;

[0041] The average difference rate of soil shear strength at a certain location in the backfill area is:

[0042] ;

[0043] The average difference rate of soil weight at a certain location in the backfill area is:

[0044] ;

[0045] The average difference rate of soil compaction at a certain location in the backfill area is:

[0046] ;

[0047] The jump value of the differential rate of soil settlement deformation at a certain location in the backfill area is:

[0048] ;

[0049] The jump value of the soil shear strength difference rate at a certain location in the backfill area is:

[0050] ;

[0051] The jump value of the soil weight difference rate at a certain location in the backfill area is:

[0052] ;

[0053] The jump value of the soil compaction difference rate at a certain location in the backfill area is:

[0054] .

[0055] In step S7, the specific steps for calculating the corrected evaluation index include:

[0056] Revise evaluation indicators for:

[0057] ;

[0058] in, To correct the influence coefficient of the evaluation indicators;

[0059] The corrected evaluation indicators for a certain location in the backfill area are as follows:

[0060] Evaluation index for soil settlement and deformation correction at a certain location in the backfill area = ;

[0061] Corrected evaluation index of soil shear strength at a certain location in the backfill area , = ;

[0062] Evaluation index of soil weight correction at a certain location in the backfill area = ;

[0063] Evaluation index for soil compaction correction at a certain location in the backfill area = ;

[0064] Normalized mean difference rate of L positions at the m-th position and normalized difference rate jump value index The calculation formulas are as follows:

[0065] ;

[0066] ;

[0067] Then the normalized average difference rate index and the normalized difference rate jump value index of soil settlement deformation at the m-th location are respectively:

[0068] ;

[0069] ;

[0070] in, This represents the average difference rate of soil settlement deformation among the L locations; This represents the average difference rate of soil settlement deformation at the L locations; This represents the average difference rate of soil settlement deformation at the m-th location; This represents the largest jump in the soil settlement deformation difference rate among the L locations; This represents the smallest jump value in the soil settlement deformation difference rate among the L locations; This represents the jump value of the soil settlement deformation difference rate at the m-th location;

[0071] The normalized mean difference rate index and the normalized difference rate jump value index of the soil shear strength at the m-th location are respectively:

[0072] ;

[0073] ;

[0074] in, This represents the minimum average difference rate of soil shear strength among the L locations; This represents the average difference rate of soil shear strength at the L locations; This represents the average difference rate of soil shear strength at the m-th location; This represents the largest jump in the rate of difference in soil shear strength among the L locations; This represents the smallest jump in the soil shear strength difference rate among the L locations; This represents the jump value of the soil shear strength difference rate at the m-th location;

[0075] The normalized mean difference rate index and the normalized difference rate jump value index of the soil weight at the m-th location are respectively:

[0076] ;

[0077] ;

[0078] in, This represents the minimum average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight at the m-th location; This represents the largest jump in soil weight difference rate among the L locations; This represents the smallest jump in soil weight difference rate among the L locations; This represents the jump value of the soil weight difference rate at the m-th location;

[0079] The normalized average difference rate index and the normalized difference rate jump value index of soil density at the m-th location are respectively:

[0080] ;

[0081] ;

[0082] in, This represents the minimum average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction at the m-th location; This represents the largest jump in soil compaction difference rate among the L locations; This represents the smallest jump in soil compaction difference rate among the L locations; This represents the jump value of the soil compaction difference rate at the m-th location;

[0083] Normalized average difference rate index Average difference rate:

[0084] ;

[0085] Normalized average difference rate index Difference rate jump value:

[0086] ;

[0087] Normalized average difference rate index Parameter fluctuation coefficient:

[0088] ;

[0089] Normalized Difference Rate Jump Value Indicator Average difference rate:

[0090] ;

[0091] Normalized Difference Rate Jump Value Indicator Difference rate jump value:

[0092] ;

[0093] Normalized Difference Rate Jump Value Indicator The parameter fluctuation coefficient:

[0094] ;

[0095] By normalizing the parameter fluctuation coefficient, the influence coefficient of the modified evaluation index is obtained:

[0096] ;

[0097] ;

[0098] The formula above can be used to calculate the values ​​for each position. , , , , , , , This allows for the calculation of soil settlement deformation correction evaluation indices at each location. Soil shear strength correction evaluation index Soil weight correction evaluation index Soil compaction correction evaluation index .

[0099] In step S8, the specific steps for calculating the influence coefficient of the comprehensive evaluation index include:

[0100] The normalized index at the m-th position The formula is as follows:

[0101] ;

[0102] Therefore, according to the above formula, we can obtain:

[0103] The normalized index for soil settlement deformation at the m-th location is:

[0104] ;

[0105] in, The corrected evaluation index represents the soil settlement deformation at the m-th location; The corrected evaluation index represents the minimum soil settlement deformation among L locations; The corrected evaluation index represents the maximum soil settlement deformation among L locations;

[0106] The normalized index of the soil shear strength at the m-th location is:

[0107] ;

[0108] in, The corrected evaluation index represents the soil shear strength at the m-th location; The corrected evaluation index represents the minimum soil shear strength among L locations; The corrected evaluation index represents the maximum soil shear strength among L locations;

[0109] The normalized index for the soil weight at the m-th location is:

[0110] ;

[0111] in, The corrected evaluation index represents the soil weight at the m-th location; The corrected evaluation index represents the minimum soil weight among the L locations; The corrected evaluation index represents the maximum soil weight among the L locations;

[0112] The normalized index of soil density at the m-th location is:

[0113] ;

[0114] in, The corrected evaluation index represents the soil compaction at the m-th location; The corrected evaluation index represents the minimum soil compaction among L locations; The corrected evaluation index represents the maximum soil density among L locations;

[0115] Normalized index Average difference rate:

[0116] ;

[0117] Normalized index Difference rate jump value:

[0118] ;

[0119] Normalized index The parameter fluctuation coefficient:

[0120] ;

[0121] The parameter fluctuation coefficients of the four indicators can then be calculated using the above formula. , , , ;

[0122] By normalizing the parameter fluctuation coefficient, the influence coefficient of the comprehensive evaluation index is obtained:

[0123] ;

[0124] ;

[0125] ;

[0126] .

[0127] In step S9, the comprehensive evaluation index K is: K= The allowable value for the construction quality evaluation index is [K], and [K] is set to 1.

[0128] In step S11, the remedial measures taken include grouting reinforcement, layered compaction, replacement filling, and dynamic compaction reinforcement.

[0129] The beneficial effects of this invention are:

[0130] 1) Through multi-index collaborative detection, key parameters such as soil settlement and deformation, soil shear strength, soil weight, and soil compaction are covered, comprehensively covering soil mechanical indicators and deformation characteristics, reflecting the overall quality of the backfill area.

[0131] 2) By introducing undisturbed areas as a comparison, the quality evaluation has a benchmark reference. Through multi-dimensional in-depth detection and comparison, a comprehensive evaluation index system is constructed to accurately quantify the degree of change and impact of backfill construction on the original state of the soil.

[0132] 3) Classifying quality grades based on the actual use of the project makes the evaluation results more in line with the project requirements, providing a scientific and accurate basis for controlling the quality of foundation pit backfilling, fundamentally improving the quality control level of foundation pit engineering, and effectively ensuring the long-term safe and stable operation of subsequent projects.

[0133] 4) Connect targeted remedial measures to achieve closed-loop management. For areas with medium quality levels, develop grouting reinforcement and layered compaction remedial plans; for areas with poor quality levels, develop replacement treatment and dynamic compaction remedial plans. This closely links quality inspection, grade determination, and subsequent remedial measures, forming a "testing-evaluation-improvement" quality control closed loop. This can quickly and efficiently solve backfill quality problems and ensure project safety. Attached Figure Description

[0134] Figure 1 This is a flowchart of this embodiment;

[0135] Figure 2 This is a schematic diagram showing the selection of a certain depth location in the backfill area of ​​the foundation pit in this embodiment. Detailed Implementation

[0136] The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit, as described in this invention, specifically includes the following steps:

[0137] S1: Location index detection at a specific depth in the backfill area.

[0138] At a specific location on the ground surface of the backfill area of ​​the foundation pit, at a certain depth below this location, soil settlement deformation *s* and soil shear strength are measured. Soil weight Soil density The detection method measures a series of indicators corresponding to this depth at this location, providing reliable input data for the subsequent establishment of difference rate indicators.

[0139] The aforementioned soil settlement deformation s can be measured using either leveling or sensor monitoring. The soil settlement deformation s (elevation change) at a specific depth relative to a benchmark point at a given time can be obtained using a level instrument. Alternatively, a monitoring sensor can be installed at the test depth to obtain the soil settlement deformation s at that specific depth at a given time. Both leveling and sensor monitoring methods are existing conventional methods for measuring soil settlement deformation, and their testing principles and methods will not be elaborated upon here.

[0140] The above soil shear strength The preferred method for measurement is the vane shear test.

[0141] The above soil weight The preferred method for measurement is the ring cutter method. A ring cutter of known volume is driven into the soil, and after the soil sample is taken out, its mass is determined by weighing. The weight of the soil per unit volume is calculated to obtain the soil mass γ.

[0142] The above soil compaction For cohesive soils, the ring cutter method is used for measurement, while for sandy soils and other granular soils with good compatibility, the sand cone method is used for measurement.

[0143] S2: Detection of a depth index at a specific location within an undisturbed region.

[0144] In this embodiment, the area outside the backfill area of ​​the foundation pit, at a horizontal distance from the edge of the foundation pit not less than the depth of the foundation pit, and unaffected by the excavation and backfilling of the foundation pit, is called the undisturbed area. A location is selected on the ground surface of the undisturbed area, and then a depth point is selected downwards from this location at the same depth as in step S1. The soil settlement deformation at this depth and location within the undisturbed area is measured using the same testing method as in step S1. Soil shear strength Soil weight Soil density This provides reliable input data for the establishment of subsequent difference rate indicators.

[0145] S3: Establishment of the difference rate index at a specific depth in a backfilled area.

[0146] Based on the measurement data from steps S1 and S2, a dimensionless construction difference rate index for the backfill area at a certain depth is established.

[0147]

[0148] Then, based on the above formula, we can obtain the following:

[0149] The soil settlement deformation difference rate index at a certain depth in the backfill area , ;

[0150] Soil shear strength difference rate at a certain depth in the backfill area : ;

[0151] The soil weight difference rate at a certain depth in the backfill area : ;

[0152] Soil density difference rate at a certain depth in the backfill area : .

[0153] S4: Establishment of a difference rate index for different depths at a specific location within a backfilled area.

[0154] Depth positions are set at regular intervals at selected locations in both the backfilled and undisturbed areas. , The backfill area and the undisturbed area are set accordingly. The depth positions can be set at intervals of tens of centimeters downwards from a selected location, or at intervals of several meters downwards from a selected location. In this embodiment, a depth position is set at intervals of 2 meters, i.e., depth positions are set at 2 meters, 4 meters, 6 meters, 8 meters, 10 meters, etc., downwards from a selected location. The depth positions of the backfill area and the undisturbed area correspond one-to-one, and the corresponding depth positions have the same depth. According to the above steps S1-S3, the difference rate index of different depth positions at a certain location in the backfill area is calculated respectively. , , , .

[0155] Then we get:

[0156] The indices for the differential rate of soil settlement deformation at different depths in the backfill area are as follows: ;

[0157] The soil shear strength difference rate at different depths in the backfill area are as follows: ;

[0158] The soil weight difference rate indices at different depths in the backfill area are as follows: ;

[0159] The soil compaction difference rate indices at different depths in the backfill area are as follows: ;

[0160] Based on the difference rate index obtained at different depth locations, it is possible to fully cover different strata conditions for foundation pit backfilling and accurately capture the characteristics of quality changes with depth.

[0161] S5: Establishing the average difference rate and the jump value of the difference rate at a certain location in the backfilled area

[0162] Based on the difference rate indices at different depths of a certain location in the backfill area obtained in step S4, mathematical statistics are used to construct the average difference rate and the jump value of the difference rate for the construction quality at a certain location in the backfill area. Therefore, the average difference rate of soil settlement deformation at a certain location in the backfill area is:

[0163]

[0164] The average difference rate of soil shear strength at a certain location in the backfill area is:

[0165]

[0166] The average difference rate of soil weight at a certain location in the backfill area is:

[0167]

[0168] The average difference rate of soil compaction at a certain location in the backfill area is:

[0169]

[0170] The jump value of the differential rate of soil settlement deformation at a certain location in the backfill area is:

[0171]

[0172] The jump value of the soil shear strength difference rate at a certain location in the backfill area is:

[0173]

[0174] The jump value of the soil weight difference rate at a certain location in the backfill area is:

[0175]

[0176] The jump value of the soil compaction difference rate at a certain location in the backfill area is:

[0177]

[0178] The average difference value mentioned above is used to reflect the average level of overall quality difference, while the difference rate jump value is used to reflect the dispersion of quality difference.

[0179] S6: Establishment of the average difference rate and the jump value of the difference rate at L locations in the backfilled area

[0180] L locations were selected on the ground surface of the backfill area of ​​the foundation pit. Following steps S1-S5 above, the corresponding values ​​at each of the L selected locations in the backfill area were calculated. and In step S2 above, the selection of locations in the undisturbed area can be done by selecting only one location, or by grouping the locations with the L locations selected in the backfill area, meaning that L locations are also selected in the undisturbed area. If only one location is selected in the undisturbed area, the measurement data of the L locations selected in the backfill area are respectively calculated with the measurement data of this one location in the undisturbed area, and the values ​​of the L locations in the backfill area are calculated according to the above method. and If L locations are selected in the undisturbed area corresponding to the backfill area, then the measurement data of the L locations selected in the backfill area are respectively calculated with the measurement data of the corresponding locations in the undisturbed area, and the values ​​of the L locations in the backfill area are calculated according to the above method. and In this embodiment, it is preferable to select only one location in the undisturbed area.

[0181] The average difference rate of soil settlement deformation and the jump value of soil settlement deformation difference rate at L locations in the backfill area are as follows: and .

[0182] The average difference rate of soil shear strength and the jump value of soil shear strength difference rate at L locations in the backfill area are as follows: and .

[0183] The average difference rate of soil unit weight and the jump value of soil unit weight difference rate at L locations in the backfill area are as follows: and .

[0184] The average difference rate of soil compaction and the jump value of soil compaction difference rate at L locations in the backfill area are as follows: and .

[0185] S7: Calculate the corrected evaluation index for each location in the selected backfill area.

[0186] Revise evaluation indicators for:

[0187]

[0188] in, To correct the influence coefficient of the evaluation indicators, Follow the principle of heavy normalization of indicator proportions.

[0189] The corrected evaluation indicators for a certain position are as follows:

[0190] Evaluation index for soil settlement and deformation correction at a certain location in the backfill area = ;

[0191] Corrected evaluation index of soil shear strength at a certain location in the backfill area = ;

[0192] Evaluation index of soil weight correction at a certain location in the backfill area = ;

[0193] Evaluation index for soil compaction correction at a certain location in the backfill area = .

[0194] The influence coefficient of the above-mentioned modified evaluation indicators The determination needs to be based on the test data of the backfilled area and the undisturbed area of ​​the foundation pit. The specific steps are as follows:

[0195] Calculate the influence coefficient of the modified evaluation index for the m-th position out of the selected L positions. Calculated for L positions and After dimensionless processing, the parameter fluctuation coefficient of the modified evaluation index is calculated, and finally the parameter fluctuation coefficient is normalized to obtain the influence coefficient of the modified evaluation index at the m-th position. .

[0196] Normalized mean variance index at position m and normalized difference rate jump value index The calculation formulas are as follows:

[0197]

[0198]

[0199] in, .

[0200] According to the above formula, corresponding to the specific average difference rate index and the difference rate jump value index, we can obtain:

[0201] The normalized average difference rate index and the normalized difference rate jump value index of soil settlement deformation at the m-th location are respectively:

[0202]

[0203]

[0204] in, This represents the average difference rate of soil settlement deformation among the L locations; This represents the average difference rate of soil settlement deformation at the L locations; This represents the average difference rate of soil settlement deformation at the m-th location; This represents the largest jump in the soil settlement deformation difference rate among the L locations; This represents the smallest jump value in the soil settlement deformation difference rate among the L locations; This represents the jump value of the soil settlement deformation difference rate at the m-th location.

[0205] Similarly,

[0206] The normalized mean difference rate index and the normalized difference rate jump value index of the soil shear strength at the m-th location are respectively:

[0207]

[0208]

[0209] in, This represents the minimum average difference rate of soil shear strength among the L locations; This represents the average difference rate of soil shear strength at the L locations; This represents the average difference rate of soil shear strength at the m-th location; This represents the largest jump in the rate of difference in soil shear strength among the L locations; This represents the smallest jump in the soil shear strength difference rate among the L locations; This represents the jump value of the soil shear strength difference rate at the m-th location.

[0210] The normalized mean difference rate index and the normalized difference rate jump value index of the soil weight at the m-th location are respectively:

[0211]

[0212]

[0213] in, This represents the minimum average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight at the m-th location; This represents the largest jump in soil weight difference rate among the L locations; This represents the smallest jump in soil weight difference rate among the L locations; This represents the jump value of the soil weight difference rate at the m-th location.

[0214] The normalized average difference rate index and the normalized difference rate jump value index of soil density at the m-th location are respectively:

[0215]

[0216]

[0217] in, This represents the minimum average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction at the m-th location; This represents the largest jump in soil compaction difference rate among the L locations; This represents the smallest jump in soil compaction difference rate among the L locations; This represents the jump value of the soil compaction difference rate at the m-th location.

[0218] Normalized average difference rate index Average difference rate:

[0219]

[0220] Normalized average difference rate index Difference rate jump value:

[0221]

[0222] Normalized average difference rate index Parameter fluctuation coefficient:

[0223]

[0224] Normalized Difference Rate Jump Value Indicator Average difference rate:

[0225]

[0226] Normalized Difference Rate Jump Value Indicator Difference rate jump value:

[0227]

[0228] Normalized Difference Rate Jump Value Indicator The parameter fluctuation coefficient:

[0229]

[0230] By normalizing the parameter fluctuation coefficient, the influence coefficient of the modified evaluation index is obtained:

[0231]

[0232]

[0233] Obviously, The overall difference and dispersion are two dimensions of the same indicator, and the sum of the influence coefficients needs to reflect the comprehensive influence ratio of the indicator.

[0234] The formula above can be used to calculate the values ​​for each position. , , , , , , , This allows for the calculation of soil settlement deformation correction evaluation indices at each location. Soil shear strength correction evaluation index Soil weight correction evaluation index Soil compaction correction evaluation index .

[0235] S8: Calculate the influence coefficient of the comprehensive evaluation index

[0236] Based on the L positions calculated in step S7 , , , Calculate the influence coefficient of the comprehensive evaluation index. The specific calculation follows these steps:

[0237] For L positions corresponding , , , After performing dimensionless processing, the parameter fluctuation coefficients of each indicator are calculated, and finally the parameter fluctuation coefficients are normalized to obtain the influence coefficient of the comprehensive evaluation index. .

[0238] The modified evaluation index is normalized to obtain the normalized index at the m-th position. , The value is between [0,1], and the formula is as follows:

[0239]

[0240] Therefore, according to the above formula, we can obtain:

[0241] The normalized index for soil settlement deformation at the m-th location is:

[0242]

[0243] in, The corrected evaluation index represents the soil settlement deformation at the m-th location; The corrected evaluation index represents the minimum soil settlement deformation among L locations; The corrected evaluation index represents the largest soil settlement deformation among L locations.

[0244] Similarly,

[0245] The normalized index of the soil shear strength at the m-th location is:

[0246]

[0247] in, The corrected evaluation index represents the soil shear strength at the m-th location; The corrected evaluation index represents the minimum soil shear strength among L locations; The corrected evaluation index represents the maximum soil shear strength among L locations.

[0248] The normalized index for the soil weight at the m-th location is:

[0249]

[0250] in, The corrected evaluation index represents the soil weight at the m-th location; The corrected evaluation index represents the minimum soil weight among the L locations; This represents the corrected evaluation index for the largest soil weight among the L locations.

[0251] The normalized index of soil density at the m-th location is:

[0252]

[0253] in, The corrected evaluation index represents the soil compaction at the m-th location; The corrected evaluation index represents the minimum soil compaction among L locations; The corrected evaluation index represents the maximum soil compaction among L locations.

[0254] Normalized index Average difference rate:

[0255]

[0256] Normalized index Difference rate jump value:

[0257]

[0258] Normalized index The parameter fluctuation coefficient:

[0259]

[0260] The parameter fluctuation coefficients of the four indicators can then be calculated using the above formula. , , , .

[0261] By normalizing the parameter fluctuation coefficient, the influence coefficient of the comprehensive evaluation index is obtained:

[0262]

[0263]

[0264]

[0265]

[0266] Obviously, The four major indicators of soil settlement deformation, soil shear strength, soil weight, and soil compaction collectively cover the core parameters of backfill quality, and the sum of their weights needs to be fully quantified to determine the overall quality level.

[0267] S9: Construction of Comprehensive Evaluation Indicators for Construction Quality in Backfill Areas

[0268] Choose any one of the L locations selected in the backfill area, and construct a comprehensive evaluation index K based on the influence coefficient of the corrected evaluation index of the selected location calculated in step S7 and the comprehensive evaluation index calculated in step S8.

[0269] K=

[0270] Set an allowable value [K] for the construction quality evaluation index of the foundation pit backfill area. When K is less than [K], the construction quality of the foundation pit backfill area is judged to meet the requirements; when K is greater than or equal to [K], the construction quality of the foundation pit backfill area is judged to not meet the requirements.

[0271] The method for determining the allowable value [K] of the construction quality evaluation index for the backfill area of ​​the foundation pit is as follows: taking the soil index of the undisturbed area as the benchmark, the critical difference rate that meets the long-term stability of the project is derived; combined with the measured value of K of a large number of qualified foundation pit projects, the lower limit of the 95% confidence interval is taken; and it is determined strictly in accordance with the relevant requirements of the "Standard for Acceptance of Construction Quality of Building Foundation Engineering" GB50202 to eliminate the subjective influence of expert review and fine-tuning.

[0272] S10: Classification of Comprehensive Evaluation Levels for Construction Quality

[0273] Based on the comprehensive evaluation index K, combined with the future use of the backfilled area and the importance of the project, and through statistical data from numerous engineering examples, the construction quality is divided into four levels: excellent, good, medium, and poor. The comprehensive evaluation level classification table for construction quality is shown in Table 1.

[0274] Table 1

[0275]

[0276] S11: Improvement of construction quality level in backfill areas

[0277] Different remedial measures can be taken for backfill areas with grades of medium and poor, which can improve the quality of the foundation pit backfill area in a targeted manner. The construction quality of the backfill area after the remedial measures are implemented can be comprehensively monitored by the above steps. If the quality reaches the excellent or good grade, it can meet the needs of general projects.

[0278] Based on the comprehensive evaluation level of construction quality, the construction quality of the backfill area with a medium grade is improved by grouting reinforcement or layered compaction; the construction quality of the backfill area with a poor grade is improved by replacement treatment or dynamic compaction reinforcement.

[0279] Specifically, when the quality grade of the backfill area of ​​the foundation pit is determined to be medium, one of the following remedial measures can be selected to improve the quality to an excellent or good grade:

[0280] 1) Grouting reinforcement: First, drill holes in the backfill soil. The spacing between the holes is determined according to the soil conditions and the grouting effect, generally 1-2 meters. Cement grout is injected into the holes through grouting equipment, so that the grout diffuses and penetrates in the soil, fills the soil pores, and improves the soil density and strength.

[0281] 2) Layered compaction: The backfill area is re-compacted in layers. The compaction thickness of each layer is determined based on the soil type and the performance of the compaction equipment. A road roller or vibratory rammer is used to compact the soil according to the specified number of passes, ensuring the required degree of compaction is achieved.

[0282] When the quality grade of the backfill area of ​​the foundation pit is determined to be poor, one of the following remedial measures can be selected to improve the quality to an excellent or good grade:

[0283] 1) Replacement treatment: For backfill areas with poor quality, replacement treatment is required due to the serious substandard soil quality. First, the unqualified backfill soil is excavated, transported to a designated location, and then backfilled with soil that meets the design requirements.

[0284] 2) Dynamic compaction reinforcement: Dynamic compaction is used to reinforce the backfilled area. The weight of the hammer and the drop height of the dynamic compaction equipment are determined according to the soil conditions and design requirements. The hammer weight is 10-25 tons, and the drop height is 10-20 meters. The spacing and arrangement of the dynamic compaction points are square or staggered. Through multiple dynamic compactions, the soil is fully compacted, improving the soil strength and density.

[0285] The following example, a foundation pit project for an underground parking garage in a residential community in a certain city, will be used for further explanation. The foundation pit is 8m deep, and the backfill soil is mainly a mixture of cohesive soil and a small amount of sandy soil. This backfill will later serve as the foundation for the garage floor, thus requiring high quality. The method of this invention is used to evaluate the construction quality of the backfill area of ​​the foundation pit. The specific process is as follows:

[0286] Various indicators were tested at different depths at a specific location within the backfill area of ​​the foundation pit:

[0287] At a certain location, detection depth positions were set down at intervals of 2m, for a total of four depth positions. The heights of the four depth positions from the ground at the certain location were h1=2m, h2=4m, h3=6m, and h4=8m, respectively. Detection was carried out at each depth position.

[0288] Soil settlement and deformation detection: Soil settlement and deformation indices at various depths are measured using a level or monitoring sensors. =0.8mm =1.1mm =1.3mm =1.5mm.

[0289] Soil shear strength testing: After drilling and sampling, the compressive strength is measured using a pressure testing machine. Combined with in-situ vane shear tests, the soil shear strength indices at each depth are obtained. =32kPa =30kPa =28kPa =26kPa.

[0290] Soil weight measurement: The soil is weighed according to the soil testing standards to obtain the soil weight index. =19kN / m³ =18.5kN / m³ =18kN / m³ =17.5kN / m³.

[0291] Soil compaction testing: The ring sampler method is used for cohesive soil, and the sand cone method is used for sandy soil, to obtain the soil compaction index. =92%, =90%, =88%, =86%.

[0292] Various indicators were measured at different depths within a specific location in an undisturbed area:

[0293] In an undisturbed area 8m outside the edge of the excavation pit, a location was selected, and four depth points were set downwards from this location: h1=2m, h2=4m, h3=6m, and h4=8m. Measurements were taken at each depth point, and the results are as follows:

[0294] Soil settlement and deformation index. =0.3mm =0.4mm =0.5mm =0.6mm.

[0295] Soil shear strength index =40kPa =38kPa =36kPa =34kPa.

[0296] Soil weight index =20kN / m³ =19.5kN / m³ =19kN / m³ =18.5kN / m³.

[0297] Soil compaction index =96%, =95%, =94%, =93%.

[0298] Calculate the difference rate index at four depth locations:

[0299] Calculate the difference rate of each indicator at each depth location according to the difference rate index formula:

[0300] Soil settlement deformation difference rate index: =(0.8-0.3) / 0.3=1.67、 =(1.1-0.4) / 0.4=1.75、 =(1.3-0.5) / 0.5=1.6、 =(1.5-0.6) / 0.6=1.5.

[0301] Soil shear strength difference rate index: =(32-40) / 40=-0.2、 =(30-38) / 38=-0.21、 =(28-36) / 36=-0.22、 =(26-34) / 34=-0.24.

[0302] Soil weight difference rate index: =(19-20) / 20=-0.05、 =(18.5-19.5) / 19.5=-0.051、 =(18-19) / 19=-0.053、 =(17.5-18.5) / 18.5=-0.054.

[0303] Soil compaction difference rate index: =(92-96) / 96=-0.042、 =(90-95) / 95=-0.053、 =(88-94) / 94=-0.064、 =(86-93) / 93=-0.075.

[0304] The difference rate indicators at each depth location were compiled to form a complete dataset: =[1.67,1.75,1.6,1.5]、 =[-0.2,-0.21,-0.22,-0.24]、 =[-0.05,-0.051,-0.053,-0.054]、 =[-0.042,-0.053,-0.064,-0.075].

[0305] Calculate the average difference rate and the difference rate jump value at a given location:

[0306] Soil settlement deformation: average difference rate =(1.67+1.75+1.6+1.5) / 4=1.63, the jump value of the difference rate. =[(1.67-1.63)²+(1.75-1.63)²+(1.6-1.63)²+(1.5-1.63)²] / 4=0.008.

[0307] Soil shear strength: average difference rate =(-0.2-0.21-0.22-0.24) / 4=-0.2175, the jump value of the difference rate. =0.000169.

[0308] Soil weight: average difference rate =(-0.05-0.051-0.053-0.054) / 4=-0.052, the jump value of the difference rate. =0.0000017.

[0309] Soil compaction: average difference rate =(-0.042-0.053-0.064-0.075) / 4=-0.059, the jump value of the difference rate. =0.00019.

[0310] Construct comprehensive evaluation indicators:

[0311] Multiple locations were selected on-site, and the average difference rate and the jump value of the difference rate were calculated for each location. Then, the influence coefficient and the corrected evaluation index of the multiple locations were calculated using the data from the multiple locations. The influence coefficient of the comprehensive evaluation index was calculated based on the corrected evaluation index of the multiple locations. One location was selected to construct the comprehensive evaluation index, and [K]=1.0 was set.

[0312] Choose one location from among multiple locations selected on-site. The corrected evaluation index calculated for this location is: =0.6×1.63+0.4×0.008=0.982、 =0.6×(-0.2175)+0.4×0.000169=-0.130、 =0.6×(-0.052)+0.4×0.0000017=-0.031、 =0.6×(-0.0585)+0.4×0.00019=-0.035.

[0313] Impact coefficient of comprehensive evaluation indicators: =0.3、 =0.3、 =0.2、 =0.2

[0314] Comprehensive evaluation index: K=0.3×0.982+0.3×(-0.130)+0.2×(-0.031)+0.2×(-0.035)=0.295-0.039-0.006-0.007=0.243.

[0315] Since K < [K], the backfill quality is deemed to meet the basic requirements.

[0316] Quality grade classification:

[0317] Since K=0.243, K<1.2K, and the construction quality of the backfill area of ​​the foundation pit is judged to be excellent.

[0318] Quality Improvement and Re-inspection:

[0319] Because the quality level is excellent, no remedial measures are required in this embodiment. Subsequent random inspections, conducted according to the project schedule, will repeat the above testing steps. The results will remain consistently excellent, confirming that the long-term safe use requirements of the garage floor foundation are met.

Claims

1. A comprehensive testing and evaluation method for the construction quality of the backfill area of ​​a foundation pit, characterized in that, Includes the following steps: S1: Testing of various indicators at a certain depth below a certain location on the ground surface of the backfill area; these indicators include soil settlement deformation, soil shear strength, soil weight, and soil density. S2: Detection of various indicators at a certain depth below a certain location on the ground in the undisturbed area; the height of a certain depth location in the undisturbed area from the ground is the same as that of a certain depth location in the backfilled area; S3: Based on the detection values ​​of each indicator in S1 and S2, establish a difference rate index for a specific depth location at a certain position in the backfill area; the difference rate index for a specific depth location at a certain position in the backfill area is as follows: The soil settlement deformation difference rate index at a certain depth in the backfill area , ; Soil shear strength difference rate at a certain depth in the backfill area : ; The soil weight difference rate at a certain depth in the backfill area : ; Soil density difference rate at a certain depth in the backfill area : ; Where s is the soil settlement deformation in the backfill area of ​​the foundation pit; The shear strength of the soil in the backfill area of ​​the foundation pit; The weight of the soil in the backfill area of ​​the foundation pit; The soil compaction density in the backfill area of ​​the foundation pit; For soil settlement and deformation in undisturbed areas, For the soil shear strength in the undisturbed area, For the soil weight in the undisturbed area, The soil density in the undisturbed area; S4: At regular intervals, set depth points at a specific location on the ground in both the backfilled and undisturbed areas. Following steps S1-S3, establish the difference rate index for different depth points at a given location in the backfilled area; corresponding indices are set for the backfilled and undisturbed areas. depth position , The difference rate indices at different depths downward from a certain location in the backfill area are as follows: The index of soil settlement and deformation difference rate at different depths in the backfill area is: ； The soil shear strength difference rate index at different depths in the backfill area is as follows: ； The soil weight difference rate index at different depths in the backfill area is as follows: ； The soil compaction difference rate index at different depths in the backfill area is as follows: ； S5: Based on the difference rate index at different depths within a specific location in the backfill area, calculate the average difference rate and the difference rate jump value for that location; the average difference rate and the difference rate jump value for that location within the backfill area are as follows: The average difference rate of soil settlement deformation at a certain location in the backfill area is: ； The average difference rate of soil shear strength at a certain location in the backfill area is: ； The average difference rate of soil weight at a certain location in the backfill area is: ； The average difference rate of soil compaction at a certain location in the backfill area is: ； The jump value of the differential rate of soil settlement deformation at a certain location in the backfill area is: ； The jump value of the soil shear strength difference rate at a certain location in the backfill area is: ； The jump value of the soil weight difference rate at a certain location in the backfill area is: ； The jump value of the soil compaction difference rate at a certain location in the backfill area is: ； S6: Take L locations on the ground in the backfill area, and calculate the average difference rate and the difference rate jump value of the L locations according to steps S1-S5 respectively; S7: Based on the average difference rate and the jump value of the difference rate at L locations, calculate the corrected evaluation index for each of the L locations in the backfill area; the specific steps for calculating the corrected evaluation index include: Revise evaluation indicators for: ； in, To correct the influence coefficient of the evaluation indicators; The corrected evaluation indicators for a certain location in the backfill area are as follows: Evaluation index for soil settlement and deformation correction at a certain location in the backfill area = ; Corrected evaluation index of soil shear strength at a certain location in the backfill area , = ; Evaluation index of soil weight correction at a certain location in the backfill area = ; Evaluation index for soil compaction correction at a certain location in the backfill area = ; Normalized mean difference rate of L positions at the m-th position and normalized difference rate jump value index The calculation formulas are as follows: ； ； Then the normalized average difference rate index and the normalized difference rate jump value index of soil settlement deformation at the m-th location are respectively: ； ； in, This represents the average difference rate of soil settlement deformation among the L locations; This represents the average difference rate of soil settlement deformation at the L locations; This represents the average difference rate of soil settlement deformation at the m-th location; This represents the largest jump in the soil settlement deformation difference rate among the L locations; This represents the smallest jump value in the soil settlement deformation difference rate among the L locations; This represents the jump value of the soil settlement deformation difference rate at the m-th location; The normalized mean difference rate index and the normalized difference rate jump value index of the soil shear strength at the m-th location are respectively: ； ； in, This represents the minimum average difference rate of soil shear strength among the L locations; This represents the average difference rate of soil shear strength at the L locations; This represents the average difference rate of soil shear strength at the m-th location; This represents the largest jump in the rate of difference in soil shear strength among the L locations; This represents the smallest jump in the soil shear strength difference rate among the L locations; This represents the jump value of the soil shear strength difference rate at the m-th location; The normalized mean difference rate index and the normalized difference rate jump value index of the soil weight at the m-th location are respectively: ； ； in, This represents the minimum average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight among the L locations; This represents the average difference rate of soil weight at the m-th location; This represents the largest jump in soil weight difference rate among the L locations; This represents the smallest jump in soil weight difference rate among the L locations; This represents the jump value of the soil weight difference rate at the m-th location; The normalized average difference rate index and the normalized difference rate jump value index of soil density at the m-th location are respectively: ； ； in, This represents the minimum average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction among the L locations; This represents the average difference rate of soil compaction at the m-th location; This represents the largest jump in soil compaction difference rate among the L locations; This represents the smallest jump in soil compaction difference rate among the L locations; This represents the jump value of the soil compaction difference rate at the m-th location; Normalized average difference rate index Average difference rate: ； Normalized average difference rate index Difference rate jump value: ； Normalized average difference rate index Parameter fluctuation coefficient: ； Normalized Difference Rate Jump Value Indicator Average difference rate: ； Normalized Difference Rate Jump Value Indicator Difference rate jump value: ； Normalized Difference Rate Jump Value Indicator The parameter fluctuation coefficient: ； By normalizing the parameter fluctuation coefficient, the influence coefficient of the modified evaluation index is obtained: ； ； The formula above can be used to calculate the values ​​for each position. , , , , , , , This allows for the calculation of soil settlement deformation correction evaluation indices at each location. Soil shear strength correction evaluation index Soil weight correction evaluation index Soil compaction correction evaluation index ; S8: Calculate the influence coefficient of the comprehensive evaluation index based on the modified evaluation indicators for L positions; the specific steps for calculating the influence coefficient of the comprehensive evaluation index include: The normalized index at the m-th position The formula is as follows: ； Therefore, according to the above formula, we can obtain: The normalized index for soil settlement deformation at the m-th location is: ； in, The corrected evaluation index represents the soil settlement deformation at the m-th location; The corrected evaluation index represents the minimum soil settlement deformation among L locations; The corrected evaluation index represents the maximum soil settlement deformation among L locations; The normalized index of the soil shear strength at the m-th location is: ； in, The corrected evaluation index represents the soil shear strength at the m-th location; The corrected evaluation index represents the minimum soil shear strength among L locations; The corrected evaluation index represents the maximum soil shear strength among L locations; The normalized index for the soil weight at the m-th location is: ； in, The corrected evaluation index represents the soil weight at the m-th location; The corrected evaluation index represents the minimum soil weight among the L locations; The corrected evaluation index represents the maximum soil weight among the L locations; The normalized index of soil density at the m-th location is: ； in, The corrected evaluation index represents the soil compaction at the m-th location; The corrected evaluation index represents the minimum soil compaction among L locations; The corrected evaluation index represents the maximum soil density among L locations; Normalized index Average difference rate: ； Normalized index Difference rate jump value: ； Normalized index The parameter fluctuation coefficient: ； The parameter fluctuation coefficients of the four indicators can then be calculated using the above formula. , , , ; By normalizing the parameter fluctuation coefficient, the influence coefficient of the comprehensive evaluation index is obtained: ； ； ； ； S9: Based on the influence coefficients of the modified evaluation index and the comprehensive evaluation index, construct a comprehensive evaluation index for the construction quality of the backfill area, and set an allowable value for the construction quality evaluation index of the backfill area. When the comprehensive evaluation index value is less than the allowable value for the construction quality evaluation index of the backfill area, it is determined that the construction quality of the foundation pit backfill area meets the requirements; when the comprehensive evaluation index value is greater than or equal to the allowable value for the construction quality evaluation index of the backfill area, it is determined that the construction quality of the foundation pit backfill area does not meet the requirements.

2. The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit according to claim 1, characterized in that, It also includes the following steps: S10: Based on comprehensive evaluation indicators, combined with the later use of the backfill area and the importance of the project, the construction quality comprehensive inspection and evaluation level is classified. S11: Based on the classification level, take remedial measures to improve the construction quality level of the backfill area.

3. The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit according to claim 1 or 2, characterized in that, In steps S1 and S2, soil settlement deformation is measured using leveling or sensor monitoring, soil shear strength is measured using vane shear test, soil weight is measured using ring cutter method, and soil compaction is measured using ring cutter method for cohesive soil and sand cone method for granular soil.

4. The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit according to claim 1, characterized in that, In step S9, the comprehensive evaluation index K is: K= The allowable value for the construction quality evaluation index is [K], and [K] is set to 1.

5. The comprehensive testing and evaluation method for construction quality in the backfill area of ​​a foundation pit according to claim 2, characterized in that, In step S11, the remedial measures taken include grouting reinforcement, layered compaction, replacement filling, and dynamic compaction reinforcement.

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