An energy-saving and environment-friendly vacuum preloading foundation treatment method

Abstract

The present application relates to the technical field of civil engineering, and particularly relates to an energy-saving and environment-friendly vacuum preloading foundation treatment method, which comprises the following steps: dividing a foundation soil body into a plurality of foundation units, installing a plurality of vacuum pumps according to initial operation parameters; pre-pumping the foundation, judging a vacuum state of any foundation unit, adjusting pumping power of a corresponding vacuum pump or predicting required power, and twice measuring vacuum pressure under a membrane of the foundation unit; judging a consolidation state of the foundation unit according to pore water pressure, detecting fluctuation of the pore water pressure change to determine a consolidation stage of the foundation; in the main consolidation stage, drawing a vacuum pressure change curve in the membrane to judge a curve change trend, and according to the curve fluctuation, determining stability of the vacuum pressure in the membrane and a working state of the sealing membrane; in the secondary consolidation stage, measuring ground subsidence height to predict whether the vacuum preloading reaches a design requirement load. The present application improves efficiency and accuracy of the vacuum preloading treatment by evaluating consolidation degree and stability of the foundation soil body.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to an energy-saving and environmentally friendly method for vacuum preloading foundation treatment. Background Technology

[0002] In architecture, foundation treatment is of paramount importance. The stability of the superstructure depends irreplaceably on the foundation, and the main purpose of foundation treatment is to improve soil conditions using various methods. Vacuum preloading, as a new generation of soft soil foundation reinforcement method, is widely used in the construction of ports, docks, airports, industrial and civil buildings due to its advantages such as short construction period, construction safety, no environmental pollution, and low cost. However, the lag in theoretical research limits its further promotion and application in engineering.

[0003] Chinese Patent Publication No. CN104727298A discloses a method for treating soft soil foundations using vacuum preloading. This method involves setting at least three vertical vacuum pressure observation holes at at least three different treatment depths in the soft soil foundation to be treated. A pressure measuring tube is installed inside each vacuum pressure observation hole, and a vacuum pressure gauge is connected to the upper end of the tube. Surface settlement observation is then conducted on the surface of the soft soil foundation near the opening of each vacuum pressure observation hole. After the formation of the ground vacuum pressure field and the end of the rapid surface settlement phase followed by a stable settlement phase, intermittent vacuum preloading control is initiated, involving multiple cycles of intermittent pump stop-start. However, this method for treating soft soil foundations using vacuum preloading has the following problems:

[0004] If the vacuum preloading process is stopped, the pore water pressure in the soil will rise, causing the soil strength to decrease, thereby reducing the bearing capacity of the foundation and causing uneven settlement of the foundation, which will affect the safety and stability of the building.

[0005] Cyclic operations increase the construction time of vacuum preloading, which in turn increases the impact of construction on the surrounding environment and the energy consumption and environmental pollution during the construction process. Summary of the Invention

[0006] Therefore, this invention provides an energy-saving and environmentally friendly vacuum preloading foundation treatment method to overcome the problems in the prior art where soil pore water pressure rise leads to uneven settlement of the foundation, increasing energy consumption and environmental pollution, and affecting the safety and stability of buildings.

[0007] To achieve the above objectives, the present invention provides an energy-saving and environmentally friendly vacuum preloading foundation treatment method, comprising:

[0008] The foundation soil is divided into several foundation units according to the controlled area. A vacuum pump is installed in each foundation unit. The vacuum pump installed in each foundation unit is started according to the preset initial working parameters.

[0009] The vacuum state of any foundation unit is determined based on the vacuum pressure under the membrane in each foundation unit.

[0010] The pumping power of the vacuum pump in the corresponding foundation unit is determined by the vacuum state, and the power demand of the corresponding vacuum pump is predicted.

[0011] Adjust the suction power of the vacuum pump to the determined rated power range, and re-acquire the sub-membrane vacuum pressure of the foundation unit;

[0012] The timing for determining the consolidation state of the foundation unit is confirmed based on the re-acquired subsurface vacuum pressure, and the consolidation stage of the foundation unit is determined.

[0013] Based on the determined consolidation stage of the foundation unit, determine the fluctuation of vacuum preloading and the working state of the sealing membrane, or predict whether the vacuum preloading will reach the design load requirements.

[0014] Furthermore, the vacuum pressure under the membrane of any foundation unit is measured and compared with the standard value range. For foundation units that are not within the standard value range, it is determined whether they are in the first vacuum state or the third vacuum state, and the corresponding vacuum pump suction power needs to be adjusted.

[0015] Furthermore, when it is determined that the vacuum pump's suction power needs to be adjusted, for the foundation unit in the third vacuum state, the suction power of the corresponding vacuum pump is reduced, and the reduction range is determined by the ratio of the vacuum pressure under the membrane to the standard value range.

[0016] For a foundation unit in the first vacuum state, predict the required power of the vacuum pump that needs adjustment, compare it with the rated power of the vacuum pump, and determine whether the control area of ​​the vacuum pump needs to be adjusted.

[0017] Furthermore, after re-acquiring the vacuum pressure under the membrane of the foundation unit, the vacuum state of the foundation unit is confirmed again. When any foundation unit is in the second vacuum state, formal vacuum preloading is performed according to the determined initial working parameters to determine the consolidation state of the foundation unit.

[0018] Furthermore, the process of determining the consolidation state of the foundation unit includes,

[0019] Detect pore water pressure at different depths to determine whether the average descent rate of the foundation unit at different depths is within the normal range.

[0020] Based on the proportion of drainage boards outside the normal range within the foundation unit, determine whether the foundation soil of the corresponding foundation unit is uniformly consolidated.

[0021] When the foundation soil is unevenly consolidated, reduce the gap between the drainage boards in the corresponding foundation unit.

[0022] Furthermore, the process of determining the foundation consolidation stage includes,

[0023] The variance value is calculated based on the average pore water pressure at the same depth within the drainage board of the foundation unit. This variance is then compared with the critical value to determine the fluctuation of pore water pressure changes and to ascertain whether the foundation unit is in the primary consolidation stage or the secondary consolidation stage.

[0024] Furthermore, when the foundation is in the primary consolidation stage, a change curve is plotted based on the vacuum pressure inside the membrane, and the derivative function of the change curve is calculated accordingly to determine the trend of the change curve.

[0025] When the curve shows an upward trend, it is determined that the vacuum pressure inside the membrane is continuously rising. The pumping power of the vacuum pump is reduced, and the range of reduction is determined by the ratio of the absolute value of the derivative function to the standard speed.

[0026] When the curve shows a downward trend, it is determined that the vacuum pressure inside the membrane is approaching the standard pressure, and the curve exhibits fluctuations.

[0027] When the derivative of the curve is determined to be zero, the pumping power of the vacuum pump is reduced, and the reduction range is determined based on the ratio of the vacuum pressure to the standard pressure on the curve at that moment.

[0028] Furthermore, when the change curve exhibits fluctuations,

[0029] By comparing the absolute value of the derivative function at that moment with the standard velocity, it can be determined whether the vacuum pressure inside the membrane is stable, and subsequent continuous pumping can be carried out, or the foundation can be preloaded by a combination of vacuum and load preloading.

[0030] Furthermore, the process of determining the working state of the sealing membrane includes,

[0031] By comparing the intramural vacuum pressure on the change curve with the standard pressure and combining the corresponding derivative function value, it can be determined whether the sealing membrane is damaged.

[0032] When the corresponding derivative value is zero, increase the pumping power of the vacuum pump, and determine the range of increase based on the ratio of vacuum pressure to standard pressure on the curve at that moment.

[0033] Furthermore, when the foundation is in the secondary consolidation stage, the average ground settlement rate is calculated based on the ground settlement.

[0034] If the average ground settlement rate is determined to be greater than the standard settlement rate, it is determined that the vacuum preloading has not reached the design load, and the foundation is continuously pumped.

[0035] When the number of consecutive days in which the average ground settlement rate is less than or equal to the standard settlement rate is greater than or equal to the standard number of days, it is determined that the vacuum preloading has reached the design load, and vacuum preloading of the foundation is stopped.

[0036] Compared with existing technologies, the beneficial effects of this invention are as follows: Vacuum preloading foundation is an engineering technology used to improve the bearing capacity and stability of foundations, mainly applicable to soft soil foundations. It accelerates soil consolidation and strength improvement by using a vacuum pump to extract moisture and air from the foundation soil. However, the construction process often generates a certain amount of wastewater and waste materials, such as wastewater extracted during construction and discarded sealing membranes. As the construction time increases, the potential for pollution to the surrounding environment from the extracted wastewater gradually increases. Since the distribution of moisture and air in the foundation is irregular, if the operating parameters and suction area of ​​the vacuum pump are not adjusted accordingly, energy waste will occur, and long-term noise and vibration will also affect the lives and health of nearby residents. This invention divides the foundation into units and determines the vacuum state accordingly to reflect the distribution of moisture and air in the foundation soil. Based on the distribution, the vacuum pump suction power corresponding to the foundation unit is adjusted. By adaptively adjusting the suction power, the construction time of vacuum preloading is shortened, reducing energy consumption and environmental pollution during construction, effectively reducing the impact of construction on the surrounding environment, and significantly improving the reinforcement effect of the foundation.

[0037] Furthermore, the vacuum pressure inside the membrane is a crucial parameter in the vacuum preloading process. Due to the differences in foundation soil across different areas during preloading, it is essential to avoid uniformly setting vacuum pump operating parameters for different areas of the foundation soil. This invention determines the vacuum state of the foundation unit based on the vacuum pressure under the membrane, reflecting the porosity of the foundation soil. The porosity is the ratio of the pore volume to the volume of solid particles in the soil; generally, a higher porosity indicates looser soil and higher compressibility. Different adjustment measures are taken based on the vacuum state of the foundation unit, adjusting the vacuum pump's suction power and control area to... The vacuum pressure inside the membrane of each foundation unit is controlled within an appropriate range, improving the adaptability to different conditions of the foundation soil during subsequent formal vacuum preloading. The vacuum pump's suction power and control area are adjusted according to the specific conditions of different foundation units in the foundation soil. Compared with existing preloading processes, this shortens the construction time of vacuum preloading, reduces the energy consumption caused by vacuum pump operation during preloading, and reduces the impact on the lives of surrounding residents. At the same time, by treating construction wastewater, it ensures that the discharge meets standards and environmental pollution is minimized, effectively reducing the possibility of vacuum preloading causing environmental pollution.

[0038] Furthermore, during the vacuum preloading process, the degree of consolidation of the foundation soil has a significant impact on the preloading process. During vacuum suction, water in the soil is expelled, and the pore water pressure gradually decreases. This method determines the consolidation status of the soil in each foundation unit by monitoring the changes in pore water pressure between several drainage boards, thereby judging the stability and safety of the vacuum preloaded foundation. If the pore water pressure decreases too quickly or too slowly, it may indicate uneven soil consolidation. By reducing the gap between drainage boards 2 and increasing the number of drainage boards, the stability and accuracy of the vacuum preloading process are improved. This further increases the adaptability of the preloading construction to different areas of the foundation soil, avoiding situations where uneven soil consolidation leads to delayed soil settlement, requiring secondary preloading or extending the preloading time. This effectively reduces the impact of construction on the surrounding environment and significantly improves the foundation reinforcement effect.

[0039] Furthermore, during the primary consolidation stage, foundation settlement is mainly caused by the dissipation of pore water pressure. During the secondary consolidation stage, the pore water pressure tends to stabilize, and the soil continues to undergo slow compressive deformation. This method controls and analyzes the vacuum pressure inside the membrane during the primary consolidation stage and analyzes and predicts the ground settlement during the secondary consolidation stage to determine whether the vacuum preloading meets the design load requirements. This improves the stability and flexibility of vacuum preloading analysis of the foundation and avoids the impact of prediction on the accuracy of the analysis when the foundation settlement is unstable.

[0040] Furthermore, the vacuum pressure inside the membrane is a crucial parameter in the vacuum preloading process. By plotting the vacuum pressure variation curve, the trend and volatility of the vacuum pressure within the membrane are determined. Based on the volatility of the curve, the stability of the vacuum pressure is assessed. A combined vacuum and load preloading method is used to preload the foundation. By applying an additional load, the effective stress of the soil is further increased, improving the bearing capacity of the foundation and reducing soil settlement. The sealing status of the sealing membrane is determined based on the trend of the vacuum pressure change within the membrane, preventing the pore water pressure in the soil from rising back when the sealing membrane is damaged, which would reduce the bearing capacity of the foundation and decrease the strength of the soil, affecting the stability of the foundation and subsequent construction. The operating parameters of the vacuum pump are adjusted according to the rate of increase of the vacuum pressure inside the membrane, further improving the construction efficiency of vacuum preloading of the foundation and reducing unnecessary energy consumption.

[0041] Furthermore, the average ground settlement rate refers to the average rate of ground settlement over a certain period of time. By calculating the average ground settlement rate, the settlement trend of the entire foundation can be reflected. The number of consecutive days in which the average ground settlement rate is less than or equal to the standard settlement rate can be used to determine whether the vacuum preloading has reached the design load requirement of the foundation, thereby improving the accuracy of assessing foundation stability and predicting settlement development. Attached Figure Description

[0042] Figure 1This is a flowchart illustrating the steps of the vacuum preloading foundation treatment method in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the vacuum preloading foundation treatment method in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the process for determining the vacuum state of the foundation unit in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram illustrating the determination of whether the vacuum preloading has reached the design load requirement in an embodiment of the present invention;

[0046] In the diagram: 1-vacuum pump, 2-drainage board, 3-vacuum pipe network, 4-sealing membrane, 5-sand cushion layer, 6-soil slab filling. Detailed Implementation

[0047] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0048] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0049] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0050] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] Please see Figures 1-4 As shown, Figure 1 This is a flowchart illustrating the steps of the vacuum preloading foundation treatment method in an embodiment of the present invention; Figure 2 This is a schematic diagram of the vacuum preloading foundation treatment method in an embodiment of the present invention; Figure 3This is a schematic diagram of the process for determining the vacuum state of the foundation unit in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the determination of whether the vacuum preloading has reached the design load requirement in an embodiment of the present invention.

[0052] This invention provides an energy-saving and environmentally friendly method for vacuum preloading foundation treatment, comprising:

[0053] Step S1: On the soft soil foundation, a sand cushion layer of 5 layers is laid, a sealing wall is set around the vacuum preloading zone, a vacuum pipeline network 3 is installed, and monitoring instruments are buried.

[0054] Step S2: A geotextile and a sealing membrane 4 are laid on the sand cushion layer 5. A vacuum pump 1 is installed on the sealing membrane 4. The vacuum pump extracts air through the pipeline network to form a negative pressure. The foundation soil is divided into several foundation units according to the controlled area. A vacuum pump is installed in each foundation unit. The vacuum pumps installed in each foundation unit are started according to the preset initial working parameters.

[0055] Step S3: Pre-extraction of the foundation is performed, and the vacuum state of any foundation unit is determined based on the vacuum pressure under the membrane of each foundation unit.

[0056] Step S4: Determine the pumping power of the vacuum pump in the corresponding foundation unit based on the vacuum state, and predict the required power of the corresponding vacuum pump.

[0057] Step S5: Adjust the suction power of the vacuum pump to the determined rated power range and reacquire the sub-membrane vacuum pressure of the foundation unit;

[0058] Step S6: Confirm the timing for judging the consolidation state of the foundation unit based on the re-acquired vacuum pressure under the membrane, and determine the consolidation stage of the foundation unit.

[0059] Step S7: Based on the determined consolidation stage of the foundation unit, determine the fluctuation of vacuum preloading and the working state of the sealing membrane, or predict whether the vacuum preloading has reached the design load requirement, release the vacuum to stop preloading, and remove the sealing membrane 4 and sand cushion layer 5.

[0060] The initial operating parameters include the vacuum pump's suction power and control area.

[0061] It is understood that the vacuum pipe network 3 includes a drainage board 2, a filter pipe and a plastic hose, and the installation of the vacuum pipe network 3 includes laying the filter pipe and the plastic hose. The process of installing the vacuum pipe network 3 is common knowledge to those skilled in the art and will not be described in detail here.

[0062] Before laying the sand cushion layer in five layers, measure the road surface to ensure it is flat. If there are any potholes, fill them with plain soil. When backfilling the plain soil, control the thickness to ensure the bearing capacity required by the slab-laying machine. After the plain soil is backfilled, use a level to measure the elevation of the top surface of the soil in a 10m×10m grid and inspect it. Only after it passes inspection can the sand cushion layer be constructed. The sand cushion layer 5 needs to be filled to a thickness of 40cm, with the error within the specification requirements. Use a slab-laying machine to install drainage boards 2. After the drainage boards 2 are installed, install the monitoring instruments according to the locations given on the drawings and the designated monitoring unit, and protect the instruments.

[0063] Specifically, vacuum preloading is an engineering technology used to improve the bearing capacity and stability of foundations, mainly applicable to soft soil foundations. It involves using a vacuum pump to extract moisture and air from the foundation soil, thereby accelerating soil consolidation and increasing strength. During construction, a certain amount of wastewater and waste products are often generated, such as wastewater extracted during construction and discarded sealing membranes. As the construction time increases, the potential for pollution to the surrounding environment from the extracted wastewater gradually increases. Because the distribution of moisture and air in the foundation is irregular, if the operating parameters and suction area of ​​the vacuum pump are not adjusted accordingly, energy waste will occur, and long-term noise and vibration will also affect the lives and health of nearby residents. This invention divides the foundation into units and determines the vacuum state accordingly to reflect the distribution of moisture and air in the foundation soil. Based on the distribution, the suction power of the vacuum pump corresponding to the foundation unit is adjusted. By adaptively adjusting the suction power, the construction time of vacuum preloading is shortened, reducing energy consumption and environmental pollution during construction, effectively reducing the impact of construction on the surrounding environment, and significantly improving the reinforcement effect of the foundation.

[0064] Vacuum pump 1 and filter tube are installed according to the control area of ​​vacuum pump 1, and the number of vacuum pump 1 in each area meets the requirements of the construction plan proposed in the design.

[0065] The foundation is pre-vacuumed, and the foundation soil is divided into several foundation units according to the control area of ​​the vacuum pump. The vacuum pressure under the membrane of each foundation unit is measured.

[0066] If any vacuum pressure under the membrane is less than or equal to the first standard value, then the corresponding foundation unit is determined to be in the first vacuum state.

[0067] If any vacuum pressure under the membrane is greater than the first standard value and less than or equal to the second standard value, then the corresponding foundation unit is determined to be in the second vacuum state.

[0068] If any vacuum pressure under the membrane is greater than the second standard value, the corresponding foundation unit is determined to be in the third vacuum state.

[0069] The first standard value is 60 kPa, the second standard value is 85 kPa, and the first and second standard values ​​form a standard value range.

[0070] When the foundation unit is in the third vacuum state, the pumping power of the corresponding vacuum pump is reduced according to the ratio of the vacuum pressure under the membrane to the second standard value.

[0071] When the foundation unit is in the first vacuum state, predict the required power of the vacuum pump pump that needs to be adjusted, and determine whether the control area of ​​the corresponding vacuum pump needs to be adjusted.

[0072] If the product of the ratio of the first standard value to the vacuum pressure under the membrane and the corresponding pumping power of the vacuum pump is less than or equal to the rated power of the vacuum pump, it is determined that the power demand of the vacuum pump does not exceed the operating range of the vacuum pump, and there is no need to adjust the control area of ​​the vacuum pump.

[0073] If the product of the ratio of the first standard value to the vacuum pressure under the membrane and the corresponding pumping power of the vacuum pump is greater than the rated power of the vacuum pump, it is determined that the power demand of the vacuum pump exceeds the operating range of the vacuum pump, and the control area of ​​the vacuum pump needs to be adjusted.

[0074] Specifically, the control area of ​​the vacuum pump is reduced according to the ratio of rated power to required power, and the area of ​​the foundation unit is reduced accordingly.

[0075] Specifically, the vacuum pressure inside the membrane is a crucial parameter in the vacuum preloading process. During preloading, due to differences in the foundation soil in different areas, it's crucial to avoid uniformly setting vacuum pump operating parameters for different areas of the foundation soil. This invention determines the vacuum state of the foundation unit based on the vacuum pressure under the membrane, reflecting the porosity of the foundation soil. The porosity is the ratio of the pore volume to the volume of solid particles in the soil; generally, a higher porosity indicates looser soil and higher compressibility. Different adjustment measures are taken based on the vacuum state of the foundation unit, adjusting the vacuum pump's suction power and control area to... The vacuum pressure inside the membrane of each foundation unit is controlled within an appropriate range, improving the adaptability to different conditions of the foundation soil during subsequent formal vacuum preloading. The vacuum pump's suction power and control area are adjusted according to the specific conditions of different foundation units in the foundation soil. Compared with existing preloading processes, this shortens the construction time of vacuum preloading, reduces the energy consumption caused by vacuum pump operation during preloading, and reduces the impact on the lives of surrounding residents. At the same time, by treating construction wastewater, it ensures that the discharge meets standards and environmental pollution is minimized, effectively reducing the possibility of vacuum preloading causing environmental pollution.

[0076] After adjusting the initial operating parameters of the vacuum pump, the vacuum pressure under the membrane of each foundation unit is measured a second time. When any foundation unit is in the second vacuum state, the formal vacuum pre-compression is carried out according to the adjusted vacuum pump operating parameters.

[0077] During formal vacuum preloading, the pore water pressure around several drainage boards at different depths is detected according to the initial detection cycle. In this embodiment, the pore water pressure at different depths is detected by pore water pressure gauges at different burial depths.

[0078] Understandably, pore water pressure gauges, vertical pipe piezometers, fiber optic piezometers, pneumatic piezometers, and silicon pressure piezometers can be used as needed, as long as they can detect the pore water pressure around the drainage board.

[0079] Based on several pore water pressures, calculate the average rate of decrease of pore water pressure around any drainage board during the initial detection period, and determine whether the average rate of decrease of pore water pressure around the corresponding drainage board is within the normal range according to the preset standard speed range.

[0080] The number of drainage boards 2 whose average rate of decrease in pore water pressure within the foundation unit is outside the normal range is detected, and these are compared with the total number of drainage boards 2 within the foundation unit to calculate the actual proportion.

[0081] If the actual proportion is less than or equal to the standard proportion, it is judged that the foundation soil of the corresponding foundation unit is relatively uniformly consolidated.

[0082] If the actual proportion is greater than the standard proportion, it is determined that the foundation soil of the corresponding foundation unit is not uniformly consolidated. The gap of the drainage board 2 in the corresponding foundation unit is reduced and the number of drainage boards 2 is increased.

[0083] The standard ratio is 10%, and the standard speed range is a preset value set based on historical data of pore water pressure.

[0084] Specifically, during the vacuum preloading process, the degree of consolidation of the foundation soil has a significant impact on the preloading process. During vacuum suction, water in the soil is expelled, and the pore water pressure gradually decreases. This method determines the consolidation status of the soil in each foundation unit by monitoring the changes in pore water pressure between several drainage boards 2, thereby judging the stability and safety of the vacuum preloaded foundation. If the pore water pressure decreases too quickly or too slowly, it may indicate uneven soil consolidation. By reducing the gap between drainage boards 2 and increasing the number of drainage boards 2, the stability and accuracy of the vacuum preloading process are improved. This further increases the adaptability of the preloading construction to different areas of the foundation soil, avoiding situations where uneven soil consolidation leads to delayed soil settlement, requiring secondary preloading or extending the preloading time. This effectively reduces the impact of construction on the surrounding environment and significantly improves the reinforcement effect of the foundation.

[0085] After adjusting the setting parameters of the drainage boards within the foundation unit, the average pore water pressure at the same depth for different drainage boards is calculated. The variance of the average pore water pressure is then calculated based on the initial detection cycle.

[0086] If the variance of the average pore water pressure is greater than the critical value, it is determined that the pore water pressure fluctuates greatly and the foundation is in the main consolidation stage. The vacuum pressure inside the membrane is then analyzed.

[0087] If the variance of the average pore water pressure is greater than the critical value, it is determined that the fluctuation of pore water pressure is stable and the foundation is in the secondary consolidation stage. The ground settlement is then analyzed.

[0088] The variance value is a preset value set based on the pore water pressure data of the secondary consolidation stage.

[0089] Specifically, during the primary consolidation stage, foundation settlement is mainly caused by the dissipation of pore water pressure. During the secondary consolidation stage, the pore water pressure tends to stabilize, and the soil continues to undergo slow compression deformation. This method controls and analyzes the vacuum pressure inside the membrane during the primary consolidation stage and analyzes and predicts the ground settlement during the secondary consolidation stage to determine whether the vacuum preloading meets the design load requirements. This improves the stability and flexibility of vacuum preloading analysis of the foundation and avoids the impact of prediction on the accuracy of the analysis when the foundation settlement is unstable.

[0090] In this embodiment, the vacuum pressure inside the membrane is detected by a vacuum pressure gauge. When the foundation is in the main consolidation stage, the change curve of the vacuum pressure inside the membrane is plotted, and the derivative function of the curve is calculated accordingly.

[0091] If the vacuum pressure on the membrane vacuum pressure change curve is greater than the standard pressure at any given moment, and the derivative value at that moment is greater than zero, then the curve is judged to be on an upward trend, and the membrane vacuum pressure continues to rise. The pumping power of vacuum pump 1 is reduced according to the ratio of the absolute value of the derivative to the standard speed.

[0092] If the derivative value at that moment is equal to zero, then the pumping power of vacuum pump 1 is reduced according to the ratio of vacuum pressure to standard pressure on the membrane vacuum pressure change curve at that moment.

[0093] If at any given moment the vacuum pressure on the membrane vacuum pressure change curve is greater than the standard pressure, and the derivative value at that moment is less than zero, then the curve is considered to be trending downwards, indicating that the membrane vacuum pressure is approaching the standard pressure, and the curve exhibits fluctuations.

[0094] If the absolute value of the derivative function at that moment is less than the standard velocity, then the fluctuation of the judgment curve is small, the vacuum pressure inside the membrane is relatively stable, and subsequent continuous pumping can be carried out.

[0095] If the absolute value of the derivative function at that moment is greater than the standard velocity, it indicates that the fluctuation of the curve is large and the vacuum pressure inside the membrane is relatively unstable. Therefore, a combined vacuum and load preloading method is used to preload the foundation.

[0096] When using vacuum-loaded combined preloading, vacuum should be drawn first according to the requirements of vacuum preloading. After the vacuum pressure reaches the design requirements and stabilizes, loading should be carried out and the air should be drawn out again. During loading, backfill soil should be piled on the membrane and geotextile or other protective materials should be laid underneath.

[0097] If at any given moment the vacuum pressure on the membrane vacuum pressure change curve is less than the standard pressure, and the derivative value at that moment is less than zero, and the curve shows a downward trend, then it is determined that the sealing membrane 4 is damaged, and the pump is stopped to inspect and repair the sealing membrane 4.

[0098] If at any given moment the vacuum pressure on the membrane vacuum pressure change curve is less than the standard pressure, and the derivative value at that moment is greater than zero, and the curve shows an upward trend, then it can be determined that the membrane vacuum pressure is approaching the standard pressure, and the vacuum pre-compression is in its initial stage.

[0099] If the absolute value of the derivative function is less than the standard velocity, it is determined that the rise rate of the vacuum pressure inside the membrane is slow, and the pumping power of vacuum pump 1 is increased according to the ratio of the absolute value of the derivative function to the standard velocity.

[0100] If the derivative value at that moment is zero, the pumping power of vacuum pump 1 is increased according to the ratio of vacuum pressure to standard pressure on the membrane vacuum pressure change curve at that moment.

[0101] In this embodiment, the standard pressure is 85 kPa, and the standard speed is a preset value set according to the pre-suction operating parameters;

[0102] The vacuum equipment uses a jet-type vacuum pump 1. Vacuum pump 1 is connected to the filter tube via a plastic hose and is equipped with a shut-off valve. When stopping the pump, the shut-off valve should be closed first. With the air inlet closed, the vacuum pressure of the vacuum equipment should not be less than 96 kPa; after evacuation, the vacuum level under the membrane should be maintained at not less than 85 kPa. The control area of ​​each vacuum pump 1 is 900–1100 m². 2 ;

[0103] During surcharge, after the vacuum preload reaches 80 kPa, a 40 kPa surcharge is applied in one go. During the surcharge, drainage ditches are set up at the edge of the surcharge area, and water is pumped out of the work area.

[0104] Specifically, the vacuum pressure inside the membrane is a crucial parameter in the vacuum preloading process. By plotting the vacuum pressure change curve, the trend and volatility of the vacuum pressure inside the membrane are determined. Based on the volatility of the curve, the stability of the vacuum pressure is judged. A combined vacuum and load preloading method is used to preload the foundation. By applying additional load, the effective stress of the soil is further increased, improving the bearing capacity of the foundation and reducing soil settlement. The sealing status of the sealing membrane 4 is judged based on the trend of the vacuum pressure inside the membrane to prevent the pore water pressure in the soil from rising back when the sealing membrane 4 is damaged, which would reduce the bearing capacity of the foundation and the strength of the soil, affecting the stability of the foundation and subsequent construction. Furthermore, the operating parameters of the vacuum pump 1 are adjusted according to the rising rate of the vacuum pressure inside the membrane, further improving the efficiency of vacuum preloading of the foundation and reducing unnecessary energy consumption.

[0105] During the continuous pumping process of the foundation, when the foundation is in the secondary consolidation stage, the ground settlement height is measured in real time, and the average ground settlement rate is calculated daily.

[0106] If the average ground settlement rate is greater than the standard settlement rate, it is determined that the vacuum preloading has not reached the design load, and the foundation is continuously pumped out.

[0107] If the number of consecutive days with an average ground settlement rate less than or equal to the standard settlement rate is greater than or equal to the standard number of days, then it is determined that the vacuum preloading has reached the design load requirement, and the vacuum pump 1 can be stopped to unload the load and stop the vacuum preloading of the foundation.

[0108] The standard settlement rate is 2 mm / d, the standard number of days is 10 days, and the number of consecutive days with an average ground settlement rate less than or equal to the standard settlement rate can be adjusted according to design requirements.

[0109] In this embodiment, the vacuum state of the foundation unit gradually decreases from the outside to the inside, and the standard settlement of the corresponding foundation unit gradually increases from the outside to the inside.

[0110] Specifically, the average ground settlement rate refers to the average rate of ground settlement over a certain period of time. By calculating the average ground settlement rate, the settlement trend of the entire foundation can be reflected. The number of consecutive days in which the average ground settlement rate is less than or equal to the standard settlement rate can be used to determine whether the vacuum preloading has reached the design load requirement of the foundation, thereby improving the accuracy of assessing foundation stability and predicting settlement development.

[0111] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An energy-saving and environmentally friendly vacuum preloading foundation treatment method, characterized in that, include: The foundation soil is divided into several foundation units according to the controlled area. A vacuum pump is installed in each foundation unit. The vacuum pump installed in each foundation unit is started according to the preset initial working parameters. The vacuum state of any foundation unit is determined based on the vacuum pressure under the membrane in each foundation unit. The pumping power of the vacuum pump in the corresponding foundation unit is determined by the vacuum state, and the power demand of the corresponding vacuum pump is predicted. Adjust the suction power of the vacuum pump to the determined rated power range, and re-acquire the sub-membrane vacuum pressure of the foundation unit; The timing for determining the consolidation state of the foundation unit is confirmed based on the re-acquired subsurface vacuum pressure, and the consolidation stage of the foundation unit is determined. Based on the determined consolidation stage of the foundation unit, determine the fluctuation of vacuum preloading and the working state of the sealing membrane, or predict whether the vacuum preloading will reach the design load requirements.

2. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 1, characterized in that, The foundation is pre-vacuumed, and the foundation soil is divided into several foundation units according to the control area of ​​the vacuum pump. The vacuum pressure under the membrane of any foundation unit is measured. If any vacuum pressure under the membrane is less than or equal to the first standard value, then the corresponding foundation unit is determined to be in the first vacuum state. If any vacuum pressure under the membrane is greater than the first standard value and less than or equal to the second standard value, then the corresponding foundation unit is determined to be in the second vacuum state. If any vacuum pressure under the membrane is greater than the second standard value, the corresponding foundation unit is determined to be in the third vacuum state. For foundation units that are outside the standard value range, determine whether they are in the first or third vacuum state, and adjust the corresponding vacuum pump suction power accordingly.

3. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 2, characterized in that, When it is determined that the vacuum pump's suction power needs to be adjusted, for the foundation unit in the third vacuum state, the suction power of the corresponding vacuum pump should be reduced, and the reduction range should be determined by the ratio of the vacuum pressure under the membrane to the standard value range. For a foundation unit in the first vacuum state, predict the required power of the vacuum pump that needs adjustment, compare it with the rated power of the vacuum pump, and determine whether the control area of ​​the vacuum pump needs to be adjusted.

4. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 3, characterized in that, After re-acquiring the vacuum pressure under the membrane of the foundation unit, the vacuum state of the foundation unit is confirmed again. When any foundation unit is in the second vacuum state, formal vacuum preloading is carried out according to the determined initial working parameters to determine the consolidation state of the foundation unit.

5. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 4, characterized in that, The process of determining the consolidation state of a foundation unit includes, Detect pore water pressure at different depths to determine whether the average descent rate of the foundation unit at different depths is within the normal range. Based on the proportion of drainage boards outside the normal range within the foundation unit, determine whether the foundation soil of the corresponding foundation unit is uniformly consolidated. When the foundation soil is unevenly consolidated, reduce the gap between the drainage boards in the corresponding foundation unit.

6. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 1, characterized in that, The process of determining the foundation consolidation stage includes, The variance value is calculated based on the average pore water pressure at the same depth within the drainage board of the foundation unit. This variance is then compared with the critical value to determine the fluctuation of pore water pressure changes and to ascertain whether the foundation unit is in the primary consolidation stage or the secondary consolidation stage.

7. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 6, characterized in that, When the foundation is in the primary consolidation stage, the change curve is plotted based on the vacuum pressure inside the membrane, and the derivative function of the change curve is calculated accordingly to determine the trend of the change curve. When the curve shows an upward trend, it is determined that the vacuum pressure inside the membrane is continuously rising. The pumping power of the vacuum pump is reduced, and the range of reduction is determined by the ratio of the absolute value of the derivative function to the standard speed. When the curve shows a downward trend, it is determined that the vacuum pressure inside the membrane is approaching the standard pressure, and the curve exhibits fluctuations. When the derivative of the curve is determined to be zero, the pumping power of the vacuum pump is reduced, and the reduction range is determined based on the ratio of the vacuum pressure to the standard pressure on the curve at that moment.

8. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 7, characterized in that, When the change curve exhibits fluctuations, By comparing the absolute value of the derivative function at that moment with the standard velocity, it can be determined whether the vacuum pressure inside the membrane is stable, and subsequent continuous pumping can be carried out, or the foundation can be preloaded using a vacuum-load combined preloading method.

9. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 1, characterized in that, The process of determining the working state of the sealing membrane includes, By comparing the intramural vacuum pressure on the change curve with the standard pressure and combining the corresponding derivative function value, it can be determined whether the sealing membrane is damaged. When the corresponding derivative value is zero, increase the pumping power of the vacuum pump, and determine the range of increase based on the ratio of vacuum pressure to standard pressure on the curve at that moment.

10. The energy-saving and environmentally friendly vacuum preloading foundation treatment method according to claim 6, characterized in that, When the foundation is in the secondary consolidation stage, the average ground settlement rate is calculated based on the ground settlement. If the average ground settlement rate is determined to be greater than the standard settlement rate, it is determined that the vacuum preloading has not reached the design load, and the foundation is continuously pumped. When the number of consecutive days in which the average ground settlement rate is less than or equal to the standard settlement rate is greater than or equal to the standard number of days, it is determined that the vacuum preloading has reached the design load, and vacuum preloading of the foundation is stopped.

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