A method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning

Abstract

The present invention relates to a deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning. The method effectively monitors the water levels of pipe well dewatering inside and outside the pit. According to different dewatering conditions, a multi-level graded emergency early warning scheme is established, and risk prevention measures under different emergency plans are proposed. This method can solve the problem that pipe well dewatering construction monitoring measures are not in place and the deep foundation pit dewatering process cannot be fully monitored. At the same time, the deep foundation pit dewatering emergency early warning method can avoid various risks caused by this, making the deep foundation pit dewatering emergency early warning system more operational in actual projects and serving as a reference and guidance for risk prevention in similar projects.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep foundation pit dewatering monitoring in construction engineering, in particular to a deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning. Background Art

[0002] With the development of urban construction, foundation pits are becoming deeper and larger in area, with the maximum depth reaching over 40 meters. The surrounding environment has become more complex, and environmental protection requirements are becoming increasingly stringent. At the same time, as the depth of the foundation pit increases, the groundwater level issues faced are becoming increasingly serious. According to incomplete statistics, 75% of foundation pit accidents are caused by groundwater. Due to the complex and variable geological conditions, hydrogeological conditions, and construction environment, foundation pit projects often involve many uncertainties. During construction, they can often cause deformation of the surrounding soil, drop in groundwater levels, ground subsidence, changes in underground facilities, and deformation of adjacent buildings.

[0003] Deep foundation pit monitoring has become an essential component of foundation pit construction, serving as a guiding principle for proper construction. Groundwater level monitoring is an essential component of deep foundation pit monitoring, encompassing both internal and external monitoring. Monitoring the internal groundwater level can determine whether pit dewatering meets design requirements and whether conditions for excavation have been met. According to the "GB 50202-2018 Standard for Construction Quality Acceptance of Building Foundation Engineering," the groundwater level should be controlled at 0.5 to 1.0 meters below the excavation surface before excavation begins, and the water level in the confined aquifer should be below the safe burial depth to meet surge resistance requirements. The standard also emphasizes that for foundation pit projects equipped with water-blocking curtains, the effectiveness of the curtains should be verified by observing changes in the water levels inside and outside the pit during pre-dewatering.

[0004] During construction, it's often easy to neglect monitoring the groundwater level outside the foundation pit, causing the actual water level drop inside the pit to far exceed the designed water level drop. This significantly increases the total water inflow from the pit, impacting the construction process and surrounding buildings. Therefore, in soft soil areas with complex surrounding environments and high groundwater levels, monitoring and early warning of groundwater levels inside and outside the pit are particularly important. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and propose a deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning, which can effectively monitor the dewatering water levels of pipe wells inside and outside the pit, establish an emergency early warning system, and propose risk prevention measures, which has important guiding significance for risk prevention of dewatering projects.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning comprises the following steps:

[0008] Step 1: Pre-treat the foundation pit before dewatering, and establish a two-level early warning mechanism for monitoring outside the pit and a three-level early warning mechanism for monitoring inside the pit;

[0009] Step 2: Monitor the water accumulation inside and outside the foundation pit according to the established early warning mechanism;

[0010] Step 3: Determine whether the precipitation has returned to normal. If so, continue construction; otherwise, take appropriate measures.

[0011] Furthermore, the step 1 includes the following steps:

[0012] Step 1.1: Conduct ground deformation and site geological surveys, complete hydrogeological tests, and obtain soil physical and hydrogeological parameters;

[0013] Step 1.2: Based on the soil physical parameters and hydrogeological parameters obtained in step 1.1, a three-dimensional groundwater seepage mathematical model is constructed using Feflow software based on the finite element method. After identification and verification, the groundwater seepage law is simulated and calculated, ultimately obtaining an evaluation result of the groundwater dynamic process, which provides a basis for the layout of precipitation wells.

[0014] Step 1.3: Complete the deep foundation pit dewatering design drawings and retaining structure design plan, determine the number of dewatering wells, the water output of the wells, the layout of dewatering and monitoring facilities, and the dewatering operation strategy when the pressure water level in the pit drops to the design depth;

[0015] Step 1.4: Complete the water-stop curtain construction;

[0016] Step 1.5: Complete the construction of drainage wells and monitoring wells. The monitoring wells are distributed in a circular pattern outside the pit, while the drainage wells are evenly distributed inside the pit. Power-adjustable pumps are placed in the drainage wells inside the foundation pit.

[0017] Step 1.6, establish a two-level early warning mechanism for monitoring outside the pit: the first-level early warning outside the foundation pit is caused by the surge of surrounding groundwater, and the second-level early warning outside the foundation pit is caused by the failure of the water-stop curtain; establish a three-level early warning mechanism for monitoring inside the pit: the first-level early warning mechanism inside the pit is caused by the surge of surrounding groundwater, the second-level early warning mechanism inside the pit is caused by the failure of the water-stop curtain, and the third-level early warning mechanism inside the pit is caused by the failure of all on-site precipitation and water-stopping measures.

[0018] Moreover, the physical parameters of the soil layer include: the type, depth, distribution, and engineering characteristics of the rock and soil layers within the building range, analysis and evaluation of the stability, uniformity and bearing capacity of the foundation and surrounding buildings; buried river channels, tombs, air-raid shelters, boulders and other buried objects that are unfavorable to the project.

[0019] Furthermore, the hydrogeological parameters include: groundwater burial conditions, groundwater stable water level and variation range.

[0020] Furthermore, the monitoring of water accumulation in the foundation pit in step 2 and the determination of whether the precipitation has returned to normal in step 3 include the following steps:

[0021] Step 2.1.1: Monitor the water accumulation in the foundation pit and determine whether the water level in the foundation pit exceeds the warning value. If it exceeds the warning value, proceed to step 2.1.2; otherwise, continue construction;

[0022] Step 2.1.2: Issue a Level 1 warning in the foundation pit and perform Level 1 precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, proceed to Step 2.1.3.

[0023] Step 2.1.3: Determine whether the majority of water levels in the foundation pit exceed the warning value. If more than 50% of the water levels exceed the warning value, proceed to step 2.1.4; otherwise, return to step 2.1.2.

[0024] Step 2.1.4: Conduct a secondary warning in the foundation pit and perform secondary precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction. Otherwise, proceed to step 2.1.5.

[0025] Step 2.1.5: Determine whether the total water level in the foundation pit exceeds the warning value. If so, proceed to step 2.1.6; otherwise, return to step 2.1.4.

[0026] Step 2.1.6: Issue a level 3 warning in the foundation pit, suspend construction, and conduct level 3 precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, repeat step 2.1.6.

[0027] Moreover, the first-level dewatering treatment in the foundation pit includes: continuously monitoring the dewatering situation in the foundation pit, re-optimizing the position of the pipe well dewatering points, temporarily stopping construction work in the area, and increasing the pumping power of the corresponding dewatering well.

[0028] Moreover, the secondary dewatering treatment in the foundation pit includes: activating the first-level emergency treatment plan, demonstrating the consequences of dewatering on construction, analyzing the dangers that arise, temporarily stopping construction work in the area, activating some spare wells and increasing the power of the water pump.

[0029] Moreover, the three-level dewatering treatment in the foundation pit includes: activating the second-level emergency treatment plan, activating all spare wells, increasing the power of all water pumps, increasing the number of water pumps, analyzing and proving the specific reasons for the failure of this dewatering, and taking corresponding measures.

[0030] Furthermore, the monitoring of water accumulation outside the foundation pit in step 2 and the determination of whether the precipitation has returned to normal in step 3 include the following steps:

[0031] Step 2.2.1: Monitor the water accumulation outside the foundation pit and determine whether the water level outside the foundation pit rises or falls. If the water level outside the foundation pit rises, proceed to step 2.2.2; otherwise, proceed to step 2.2.3.

[0032] Step 2.2.2: Conduct a Level 1 early warning outside the foundation pit and strengthen monitoring. Monitor water accumulation inside the foundation pit and issue corresponding early warnings.

[0033] Step 2.2.3: Conduct a secondary warning outside the foundation pit and conduct settlement monitoring. If the settlement is normal, monitor the water accumulation in the foundation pit and issue a corresponding warning. Otherwise, proceed to step 2.2.4.

[0034] Step 2.2.4: Stop work and determine whether the precipitation has returned to normal. If the precipitation has returned to normal, continue construction; otherwise, stop work.

[0035] Moreover, the specific implementation method of the settlement monitoring is: monitor the settlement of surrounding buildings and foundation pit crown beams to check whether there are any abnormal conditions. If the settlement monitoring is normal, the monitoring focus will be shifted to the water level drop in the pit; if the settlement monitoring is abnormal, construction will be stopped immediately, and after discussion and processing by all parties involved in the construction, normal conditions will be restored and construction will continue.

[0036] The advantages and positive effects of the present invention are:

[0037] This invention effectively monitors the water levels of pipe well dewatering inside and outside the pit. Based on different dewatering conditions, it establishes a multi-level, hierarchical emergency warning scheme and proposes risk prevention measures under different emergency plans. This can address the problem of inadequate monitoring measures for pipe well dewatering construction and the inability to fully monitor the deep foundation pit dewatering process. At the same time, the deep foundation pit dewatering emergency warning method avoids various risks arising from this, making the deep foundation pit dewatering emergency warning system more operational in actual projects and providing a reference and guidance for risk prevention in similar projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the present invention for monitoring water accumulation inside and outside the foundation pit and issuing corresponding early warnings;

[0039] Figure 2 This is a flow chart of the pre-treatment of foundation pit dewatering according to the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings.

[0041] A deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning comprises the following steps:

[0042] Step 1: Pre-treat the foundation pit before dewatering, and establish a two-level early warning mechanism for monitoring outside the pit and a three-level early warning mechanism for monitoring inside the pit.

[0043] like Figure 2 As shown, this step includes the following steps:

[0044] Step 1.1: Conduct ground deformation and site geological surveys, complete hydrogeological tests, and obtain soil physical and hydrogeological parameters.

[0045] Soil physical parameters include the type, depth, distribution, and engineering properties of the rock and soil layers within the building envelope; analysis and evaluation of the stability, uniformity, and bearing capacity of the foundation and surrounding structures; and the presence of buried river channels, tombs, air-raid shelters, boulders, and other objects that could pose a threat to the project. Hydrogeological parameters include the burial conditions of groundwater, its stable groundwater level, and its fluctuation range.

[0046] Step 1.2: Based on the soil physical parameters and hydrogeological parameters obtained in step 1.1, a three-dimensional groundwater seepage mathematical model is constructed using the Feflow software based on the finite element method. After identification and verification, the groundwater seepage law is simulated and calculated, and finally the evaluation results of the groundwater dynamic process are obtained to provide a basis for the layout of precipitation wells.

[0047] Step 1.3: Complete the deep foundation pit dewatering design drawings and retaining structure design plan, and determine the number of dewatering wells, the water output of the wells, the layout of dewatering and monitoring facilities, and the dewatering operation strategy when the pressure water level in the pit drops to the design depth.

[0048] Step 1.4: Complete the water-stop curtain construction.

[0049] Step 1.5: Complete the construction of drainage wells and monitoring wells. The monitoring wells are distributed in a circular pattern outside the pit, while the drainage wells are evenly distributed inside the pit. Power-adjustable pumps are placed in the drainage wells inside the foundation pit.

[0050] Step 1.6, construct a two-level early warning mechanism for monitoring outside the pit: the first-level early warning outside the foundation pit is caused by the surge of surrounding groundwater, and the second-level early warning outside the foundation pit is caused by the failure of the water-stop curtain; construct a three-level early warning mechanism for monitoring inside the pit: the first-level early warning mechanism inside the pit is caused by the surge of surrounding groundwater, the second-level early warning mechanism inside the pit is caused by the failure of the water-stop curtain, and the third-level early warning mechanism inside the pit is caused by the failure of all on-site precipitation and water-stopping measures, which seriously affects the safety and quality of the construction process.

[0051] Step 2: Monitor the water accumulation inside and outside the foundation pit according to the established early warning mechanism.

[0052] Step 3: Determine whether the precipitation has returned to normal. If so, continue construction; otherwise, take appropriate measures.

[0053] Among them, the monitoring of water accumulation in the foundation pit in step 2 and the determination of whether the precipitation has returned to normal in step 3 include the following steps:

[0054] Step 2.1.1: Monitor the water accumulation in the foundation pit and determine whether the water level in the foundation pit exceeds the warning value. If it exceeds the warning value, proceed to step 2.1.2; otherwise, continue construction.

[0055] Step 2.1.2: Issue a first-level warning in the foundation pit and perform a first-level precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, proceed to step 2.1.3.

[0056] The first-level dewatering treatment in the foundation pit in this step includes: continuously monitoring the dewatering situation in the foundation pit, re-optimizing the location of the pipe well dewatering points, temporarily stopping construction work in the area, and increasing the pumping power of the corresponding dewatering well.

[0057] Step 2.1.3: Determine whether most water levels in the foundation pit exceed the warning value. If more than 50% of the water levels exceed the warning value, proceed to step 2.1.4; otherwise, return to step 2.1.2.

[0058] Step 2.1.4: Conduct a secondary warning in the foundation pit and perform secondary precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, proceed to step 2.1.5.

[0059] The second-level dewatering treatment in the foundation pit in this step includes: activating the first-level emergency treatment plan, demonstrating the consequences of dewatering on construction, analyzing the dangers that arise, temporarily suspending construction work in the area, activating some spare wells and increasing the power of the water pump.

[0060] Step 2.1.5: Determine whether the total water level in the foundation pit exceeds the warning value. If so, proceed to step 2.1.6; otherwise, return to step 2.1.4.

[0061] Step 2.1.6: Issue a level 3 warning in the foundation pit, suspend construction, and conduct level 3 precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, repeat step 2.1.6.

[0062] In this step, the three-level dewatering treatment in the foundation pit includes: activating the second-level emergency treatment plan, activating all spare wells, increasing the power of all water pumps, increasing the number of water pumps, analyzing and proving the specific reasons for the failure of this dewatering, and taking corresponding measures.

[0063] Monitoring water accumulation outside the foundation pit in step 2 and determining whether the precipitation has returned to normal in step 3 include the following steps:

[0064] Step 2.2.1: Monitor the water accumulation outside the foundation pit and determine whether the water level outside the foundation pit is rising or falling. If the water level outside the foundation pit is rising, proceed to step 2.2.2; otherwise, proceed to step 2.2.3.

[0065] Step 2.2.2: Conduct a first-level warning outside the foundation pit and strengthen monitoring. Monitor the water accumulation in the foundation pit and issue corresponding warnings.

[0066] In this step, the first-level warning outside the foundation pit is caused by a surge in surrounding groundwater (heavy rain, flood season), and it is necessary to strengthen the monitoring of precipitation outside the pit and further shift the monitoring focus to the precipitation level inside the pit.

[0067] Step 2.2.3: Conduct a secondary warning outside the foundation pit and conduct settlement monitoring. If the settlement is normal, monitor the water accumulation in the foundation pit and issue a corresponding warning. Otherwise, proceed to step 2.2.4.

[0068] In this step, the secondary warning outside the foundation pit was caused by the failure of the water-stop curtain. The specific implementation method of settlement monitoring is to monitor the settlement of surrounding buildings and the foundation pit crown beam to check for any abnormalities. If the settlement monitoring is normal, the focus will be shifted to lowering the water level inside the pit. If the settlement monitoring is abnormal, construction will be immediately suspended. After the relevant parties have conducted a thorough investigation and treatment, normal operations can be resumed.

[0069] Step 2.2.4: Stop work and determine whether the precipitation has returned to normal. If the precipitation has returned to normal, continue construction; otherwise, stop work.

[0070] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A deep foundation pit pipe well dewatering monitoring method based on multi-level graded early warning, characterized by: The following steps are involved: Step 1: Pre-treat the foundation pit before dewatering, and establish a two-level early warning mechanism for monitoring outside the pit and a three-level early warning mechanism for monitoring inside the pit; Step 1.1: Conduct ground deformation and site geological surveys, complete hydrogeological tests, and obtain soil physical and hydrogeological parameters; Step 1.2: Based on the soil physical parameters and hydrogeological parameters obtained in step 1.1, a three-dimensional groundwater seepage mathematical model is constructed using Feflow software based on the finite element method. After identification and verification, the groundwater seepage law is simulated and calculated, ultimately obtaining an evaluation result of the groundwater dynamic process, which provides a basis for the layout of precipitation wells. Step 1.3: Complete the deep foundation pit dewatering design drawings and retaining structure design plan, determine the number of dewatering wells, the water output of the wells, the layout of dewatering and monitoring facilities, and the dewatering operation strategy when the pressure water level in the pit drops to the design depth; Step 1.4: Complete the water-stop curtain construction; Step 1.5: Complete the construction of drainage wells and monitoring wells. The monitoring wells are distributed in a circular pattern outside the pit, while the drainage wells are evenly distributed inside the pit. Power-adjustable pumps are placed in the drainage wells inside the foundation pit. Step 1.6: Establish a two-level early warning mechanism for monitoring outside the pit: the first-level early warning mechanism outside the pit is caused by a surge in surrounding groundwater, and the second-level early warning mechanism outside the pit is caused by the failure of the water-stop curtain. Establish a three-level early warning mechanism for monitoring inside the pit: the first-level early warning mechanism inside the pit is caused by a surge in surrounding groundwater, the second-level early warning mechanism inside the pit is caused by the failure of the water-stop curtain, and the third-level early warning mechanism inside the pit is caused by the complete failure of on-site precipitation and water-stopping measures. Step 2: Monitor the water accumulation inside and outside the foundation pit according to the established early warning mechanism; Step 3: Determine whether the precipitation has returned to normal. If so, continue construction; otherwise, take appropriate measures. Monitoring water accumulation in the foundation pit in step 2 and determining whether the precipitation has returned to normal in step 3 include the following steps: Step 2.1.1: Monitor the water accumulation in the foundation pit and determine whether the water level in the foundation pit exceeds the warning value. If it exceeds the warning value, proceed to step 2.1.2; otherwise, continue construction; Step 2.1.2: Issue a Level 1 warning in the foundation pit and perform Level 1 precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction; otherwise, proceed to Step 2.1.

3. Step 2.1.3: Determine whether the majority of water levels in the foundation pit exceed the warning value. If more than 50% of the water levels exceed the warning value, proceed to step 2.1.4; otherwise, return to step 2.1.

2. Step 2.1.4: Conduct a secondary warning in the foundation pit and perform secondary precipitation treatment in the foundation pit. After treatment, determine whether the precipitation has returned to normal. If it has returned to normal, continue construction. Otherwise, proceed to step 2.1.

5. Step 2.1.5: Determine whether the total water level in the foundation pit exceeds the warning value. If so, proceed to step 2.1.6; otherwise, return to step 2.1.

4. Step 2.1.6: Issue a Level 3 warning in the foundation pit, suspend construction, and conduct Level 3 dewatering treatment in the foundation pit. After treatment, determine whether the dewatering has returned to normal. If it has returned to normal, continue construction; otherwise, repeat Step 2.1.

6. Monitoring water accumulation outside the foundation pit in step 2 and determining whether the precipitation has returned to normal in step 3 include the following steps: Step 2.2.1: Monitor the water accumulation outside the foundation pit and determine whether the water level outside the foundation pit rises or falls. If the water level outside the foundation pit rises, proceed to step 2.2.2; otherwise, proceed to step 2.2.

3. Step 2.2.2: Conduct a Level 1 early warning outside the foundation pit and strengthen monitoring. Monitor water accumulation inside the foundation pit and issue corresponding early warnings. Step 2.2.3: Conduct a secondary warning outside the foundation pit and conduct settlement monitoring. If the settlement is normal, monitor the water accumulation in the foundation pit and issue a corresponding warning. Otherwise, proceed to step 2.2.

4. Step 2.2.4: Stop work and determine whether the precipitation has returned to normal. If the precipitation has returned to normal, continue construction; otherwise, stop work.

2. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1, characterized in that: The soil physical parameters include: the type, depth, distribution, and engineering properties of the rock and soil layers within the building area, and the analysis and evaluation of the stability, uniformity, and bearing capacity of the foundation and surrounding buildings.

3. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1, characterized in that: The hydrogeological parameters include: groundwater burial conditions, groundwater stable water level and variation range.

4. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1, characterized in that: The first-level dewatering treatment in the foundation pit includes: continuously monitoring the dewatering situation in the foundation pit, re-optimizing the position of the pipe well dewatering point, temporarily stopping the foundation pit construction work, and increasing the pumping power of the corresponding dewatering well.

5. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1 is characterized in that: The secondary dewatering treatment in the foundation pit includes: activating the first-level emergency treatment plan, demonstrating the consequences of dewatering on construction, analyzing the dangers that arise, temporarily stopping foundation pit construction operations, activating some spare wells and increasing the power of water pumps.

6. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1, characterized in that: The three-level dewatering treatment in the foundation pit includes: activating the second-level emergency treatment plan, activating all spare wells, increasing the power of all water pumps, increasing the number of water pumps, analyzing and demonstrating the specific reasons for the failure of this dewatering, and taking corresponding measures.

7. The method for monitoring dewatering of deep foundation pit pipe wells based on multi-level graded early warning according to claim 1, characterized in that: The specific implementation method of the settlement monitoring is: monitor the settlement of surrounding buildings and foundation pit crown beams to check whether there are any abnormal conditions. If the settlement monitoring is normal, the monitoring focus will be shifted to the water level drop in the pit; if the settlement monitoring is abnormal, construction will be stopped immediately, and after discussion and processing by all parties involved in the construction, normal conditions will be restored and construction will continue.

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