A deep foundation pit safety analysis method

Abstract

The application discloses a deep foundation pit safety analysis method, comprising the following steps: step one, data collection; step two, determining whether to adjust the data collected in step one; step three, analyzing the collected data, and if there is a risk, early warning is performed, and if there is no risk, step four is entered; and step four, normal construction. The application can determine whether to correct the data based on the deep horizontal displacement curve collection data obtained by engineering conditions and field monitoring, and then determine whether to perform support invalidation or failure early warning, whether to perform over-excavation early warning, whether to perform overturning risk early warning, whether to perform excavation process risk early warning, improve the accuracy and convenience of the foundation pit risk evaluation, and enhance the effectiveness of the foundation pit risk evaluation.

Description

Technical Field

[0001] This invention relates to a method for safety analysis of deep foundation pits, belonging to the field of foundation pit safety construction technology. Background Technology

[0002] The existing foundation pit risk assessment often uses deep foundation pit safety monitoring data to judge the state of the deep foundation pit and uses whether the alarm value exceeds the design alarm value to trigger an alarm. This has the following problems: (1) It relies too much on the design alarm value, and the current design alarm value is too conservative. Often, after the alarm is triggered, construction continues and multiple parties discuss the method of triggering the alarm value again. This solves the problem that the design alarm value is too conservative and the alarm is triggered continuously as soon as excavation begins, thus losing the function of the alarm. (2) Many technical workers on the construction site do not necessarily have professional data analysis capabilities and cannot understand the risk type of the curve in the monitoring report. This often leads to the failure to detect hidden dangers or risks in advance, which can easily cause subsequent accidents. (3) During the construction of deep foundation pits, a large amount of monitoring data and multiple monitoring curves are generated. It takes a lot of time and energy to judge them manually, which makes the real-time judgment of risk insufficient and can easily delay the time to eliminate hidden dangers or problems. Summary of the Invention

[0003] To address the issues of discrepancies between alarm values ​​and construction conditions, and the complexity of risk curves in existing technologies, this application provides a deep foundation pit safety analysis method. This method can determine whether data correction is needed based on collected engineering data and construction progress data, and whether multi-condition risk warnings should be issued, thereby improving the accuracy and convenience of foundation pit risk assessment and enhancing its effectiveness.

[0004] To solve the above technical problems, the present invention includes the following technical solutions:

[0005] A method for safety analysis of deep foundation pits includes the following steps:

[0006] Step 1: Data Collection; specifically,

[0007] Obtain the foundation pit retaining depth H, excavation depth h, foundation pit retaining insertion ratio, and the depth h of each support. n , n=1,2,…,N, where N is the number of supports;

[0008] Get the current excavation depth h x The support closest to the excavation face is the a-th support; the current excavation face is located in the b-th soil layer; and the displacement value XS of the top of the foundation pit measured at the construction site.

[0009] Obtain the start time t of each completed support. zs and end time t zj The start time t of each layer of soil excavation ts and end time ttj ;

[0010] Based on the deep horizontal displacement curve at the construction site, identify and obtain the coordinates DB(x, y) of the top displacement point, the top displacement value DW, the coordinates MB(x, y) of the maximum displacement point on the curve, the maximum displacement value MW, the curve curvature value Qz, and the depth h of the intersection point between the lowest point of the deep horizontal position and the y-axis. d Construction time T on that day;

[0011] Step 2: Determine whether the data collected in Step 1 needs adjustment; specifically:

[0012] If [DW-XS]≤0.3mm, no adjustment is needed on that day; proceed to step three.

[0013] If [DW-XS] > 0.3 mm, correct the acquired data and then proceed to step three;

[0014] Step 3: Analyze the collected data. If there is a risk, issue an early warning. If there is no risk, proceed to Step 4.

[0015] The collected data is analyzed, and warnings are issued if risks are identified. Specifically, this includes:

[0016] To determine whether to issue a support invalidation or failure warning, specifically, if T - t zs If the y-value of MB(x,y) continues to increase after 8 hours, an alert is issued indicating that the support is ineffective or has failed. If the curve curvature value Qz remains unchanged or increases, it is considered that the support has not been fully effective, and an alert is issued indicating that the support has not been fully effective.

[0017] To determine whether to issue an over-excavation warning, specifically, for the a-th support closest to the excavation face, which has not yet been constructed, but h... x - h n If the depth is greater than 30cm, it is considered over-excavation and an over-excavation warning is issued; if 8 hours > Tt tj If the value of y in MB(x,y) is greater than 0, and continues to increase, an over-excavation warning will be issued.

[0018] To determine whether to issue a capsizing risk warning or capsizing alert, specifically, if DW > 0 and the rate of increase is increasing, h d If h > h, then that side of the foundation pit is at risk of overturning. d If the displacement value continues to increase, the risk of overturning is likely to increase, and an overturning risk warning will be issued; if the displacement value at the bottom of the inclinometer is greater than 0, it is determined that overturning has already occurred, and an overturning warning will be issued.

[0019] To determine whether to issue a risk warning for the excavation process, specifically, if the maximum deformation value MB(x,y) sinking position and the turning rate Qz both increase simultaneously, a risk warning for the excavation process will be issued.

[0020] Step 4: Normal construction.

[0021] Furthermore, regarding the supporting steel support, in step three, the collected data is analyzed, and an early warning is issued if a risk is detected. This also includes:

[0022] To determine whether to issue an early warning for delayed steel support construction, specifically, for the a-th support closest to the excavation face, which is a steel support and has not yet been constructed, but 0 <h x - h n ≤30cm, construction time T and topsoil completion time t tj The difference Tt tj If the delay exceeds 8 hours, it is determined that the steel support construction is lagging behind, and an early warning for the delayed steel support construction is issued.

[0023] The present invention, by adopting the above technical solution, has the following advantages and positive effects compared with the prior art: The present invention can collect data on deep horizontal displacement curves obtained from engineering conditions and on-site monitoring, determine whether the data needs to be corrected, and then determine whether to issue warnings for ineffective or failed supports, over-excavation, overturning risk, and excavation process risks, thereby improving the accuracy and convenience of foundation pit risk assessment and enhancing the effectiveness of foundation pit risk assessment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a deep horizontal displacement curve in one embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the horizontal support and excavation surface in one embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of data entry in one embodiment of the present invention;

[0027] Figure 4 This is a flowchart of a method for safety analysis of deep foundation pits under different working conditions based on image recognition, according to an embodiment of the present invention. Detailed Implementation

[0028] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more comprehensive understanding of the deep foundation pit safety analysis method provided by the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0029] Combination Figures 1 to 4 As shown in the figure, this embodiment provides a method for safety analysis of deep foundation pits under different working conditions based on image recognition, which includes the following steps:

[0030] Step 1: Data Collection;

[0031] Obtain the foundation pit retaining depth H, excavation depth h, foundation pit retaining insertion ratio, and the depth h of each support. n n=1,2,…,N, where N is the number of supports; H, h, h n It can be determined from the construction drawings and is unrelated to the progress of construction.

[0032] Get the current excavation depth h x The closest support to the excavation face is the a-th support; the current excavation face is located in the b-th soil layer; the displacement value XS of the top of the foundation pit measured at the construction site; h x a and b can be determined by intelligent recognition devices on-site video or read from the daily construction progress report; XS can be obtained through measuring equipment such as a total station.

[0033] Obtain the start time t of each completed support. zs and end time t zj The start time t of each layer of soil excavation ts and end time t tj ;t zs t zj t ts t tj It can automatically record based on the identification of the previous construction progress, or deduce it from the recorded data of previous reports and the current day's report;

[0034] Based on the deep horizontal displacement curve at the construction site, identify and obtain the coordinates DB(x, y) of the top displacement point, the top displacement value DW, the coordinates MB(x, y) of the maximum displacement point on the curve, the maximum displacement value MW, the curve curvature value Qz, and the depth h of the intersection point between the lowest point of the deep horizontal position and the y-axis. d Construction time on that day: T.

[0035] Step 2: Determine whether the data collected in Step 1 needs adjustment; specifically:

[0036] If [DW-XS]≤0.3mm, no adjustment is needed on that day; proceed to step three.

[0037] If [DW-XS]>0.3mm, then data correction is required based on the measured top displacement value XS, and then proceed to step three. The method for data correction is as follows: refer to the test angle value to infer the inclination value and perform inclination data correction. Later, the latest bottom deformation value of the inclination measurement will be used as the new starting data for the inclination calculation of the next day.

[0038] Step 3: Analyze the collected data. If there is a risk, issue an early warning. If there is no risk, proceed to Step 4.

[0039] The collected data is analyzed, and warnings are issued if risks are identified. Specifically, this includes:

[0040] To determine whether to issue a support invalidation or failure warning, specifically, if T - t zs If the y-value of MB(x,y) continues to increase after 8 hours, a warning of ineffective or failed support is issued; if T - t zs If the y-value of MB(x,y) begins to decrease after 8 hours, and the curvature value Qz of the curve at the point of maximum displacement gradually decreases, then the construction is considered to be normal. If the curvature value Qz remains unchanged or increases, then the support is considered to have failed to fully function, and an early warning is issued for the failure of the support to fully function.

[0041] To determine whether to issue an over-excavation warning, specifically, for the a-th support closest to the excavation face, which has not yet been constructed, but h... x - h n If the depth is greater than 30cm, it is considered over-excavation, and an over-excavation warning is issued to remind relevant personnel to stop over-excavation; if 8 hours > Tt tj If the value of y in MB(x,y) is >0 and continues to increase, it is also inferred that over-mining has occurred, and an over-mining warning is issued.

[0042] To determine whether to issue a rollover risk warning, specifically, if DW > 0 and the rate of increase is increasing, h d If h > h, then there is a certain risk of overturning on that side of the foundation pit. d If the displacement continues to increase, the risk of overturning will be greater, and an overturning risk warning will be issued; if the displacement value at the bottom of the inclinometer is greater than 0, it is determined that overturning has already occurred and immediate action is required.

[0043] To determine whether to issue a risk warning for the excavation process, if the maximum deformation value MB(x,y) sinking position and the turning rate Qz both increase simultaneously, it is determined that the current excavation of the foundation pit is in a state of high risk, and a risk warning for the excavation process should be issued, requiring intervention from relevant personnel.

[0044] Step 4: Normal construction.

[0045] Furthermore, regarding the supporting steel support, in step three, the collected data is analyzed, and an early warning is issued if a risk is detected. This also includes:

[0046] To determine whether to issue an early warning for delayed steel support construction, specifically, for the a-th support closest to the excavation face, which is a steel support and has not yet been constructed, but 0 <h x - hn ≤30cm, construction time T and topsoil completion time t tj The difference Tt tj If the delay exceeds 8 hours, it is determined that the steel support construction is lagging behind, and an early warning for the delayed steel support construction is issued.

[0047] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for safety analysis of deep foundation pits, characterized in that, Includes the following steps: Step 1: Data Collection; specifically, Obtain the foundation pit retaining depth H, excavation depth h, foundation pit retaining insertion ratio, and the depth h of each support. n , n=1,2,…,N, where N is the number of supports; Get the current excavation depth h x The support closest to the excavation face is the a-th support; the current excavation face is located in the b-th soil layer; and the displacement value XS of the top of the foundation pit measured at the construction site. Obtain the start time t of each completed support. zs and end time t zj The start time t of each layer of soil excavation ts and end time t tj ; Based on the deep horizontal displacement curve at the construction site, identify and obtain the coordinates DB(x, y) of the top displacement point, the top displacement value DW, the coordinates MB(x, y) of the maximum displacement point on the curve, the maximum displacement value MW, the curve curvature value Qz, and the depth h of the intersection point between the lowest point of the deep horizontal position and the y-axis. d Construction time T on that day; Step 2: Determine whether to adjust the data collected in Step 1; specifically: If [DW-XS]≤0.3mm, no adjustment is needed on that day; proceed to step three. If [DW-XS] > 0.3mm, correct the collected data and then proceed to step three; Step 3: Analyze the collected data. If there is a risk, issue an early warning. If there is no risk, proceed to Step 4. The collected data is analyzed, and warnings are issued if risks are identified. Specifically, this includes: To determine whether to issue a support invalidation or failure warning, specifically, if T - t zs If the y-value of MB(x,y) continues to increase after 8 hours, an alert is issued indicating that the support is ineffective or has failed. If the curve curvature value Qz remains unchanged or increases, it is considered that the support has not been fully effective, and an alert is issued indicating that the support has not been fully effective. To determine whether to issue an over-excavation warning, specifically, for the a-th support closest to the excavation face, which has not yet been constructed, but h... x - h n If the depth is greater than 30cm, it is considered over-excavation and an over-excavation warning is issued; if 8 hours > Tt tj If the value of y in MB(x,y) is greater than 0, and continues to increase, an over-excavation warning will be issued. To determine whether to issue a capsizing risk warning or capsizing alert, specifically, if DW > 0 and the rate of increase is increasing, h d If h > h, then that side of the foundation pit is at risk of overturning. d If the displacement value continues to increase, the risk of overturning is likely to increase, and an overturning risk warning will be issued; if the displacement value at the bottom of the inclinometer is greater than 0, it is determined that overturning has already occurred, and an overturning warning will be issued. To determine whether to issue a risk warning for the excavation process, specifically, if the maximum deformation value MB(x,y) sinking position and the turning rate Qz both increase simultaneously, a risk warning for the excavation process will be issued. Step 4: Normal construction.

2. The deep foundation pit safety analysis method as described in claim 1, characterized in that, The support is a steel support. In step three, the collected data is analyzed, and an early warning is issued if a risk is detected. This also includes: To determine whether to issue an early warning for delayed steel support construction, specifically, for the a-th support closest to the excavation face, which is a steel support and has not yet been constructed, but 0 <h x - h n ≤30cm, construction time T and topsoil completion time t tj The difference Tt tj If the delay exceeds 8 hours, it is determined that the steel support construction is lagging behind, and an early warning for the delayed steel support construction is issued.

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