Large-strain consolidation algorithm, equipment and medium for horizontal vacuum dehydration of sludge

Abstract

The invention relates to a large-strain consolidation algorithm, equipment and medium for horizontal vacuum dehydration of sludge, and the algorithm comprises the following steps: 1, obtaining basic parameters of a constitutive relation of a target soil body through an indoor consolidation experiment and a penetration experiment, 2, obtaining load conditions of the target soil body through surveying a geological exploration report and an engineering design scheme, the method comprises the steps of (1) establishing a one-dimensional PHD consolidation model, (2) establishing a one-dimensional PHD consolidation model and deducing a control equation under equal strain conditions, (3) introducing a virtual time step and calculating the consolidation degree in a manner of carrying out segmented increment processing on time, (4) establishing the one-dimensional PHD consolidation model and deducing a control equation under equal strain conditions, and (5) calculating the final consolidation degree based on the virtual time step and the control equation, and further comprises equipment and a medium. According to the method, the influence of non-uniform consolidation is incorporated into the one-dimensional theoretical consolidation analysis of the Taisha foundation, and the consolidation coefficient is corrected by using the control equation based on the virtual time step and the strain condition, so that convenient and accurate consolidation calculation is realized.

Description

Technical Field

[0001] This invention relates to the field of sludge consolidation algorithm technology, specifically to a large-strain consolidation algorithm, device, and medium for horizontal vacuum dewatering of sludge. Background Technology

[0002] For geotechnical design of clay foundations, Terzaghi's one-dimensional (1D) consolidation theory is widely used to calculate the degree of consolidation. According to this theory, under given geometric conditions, the consolidation rate of the soil will be determined solely by the consolidation coefficient (cv). However, this premise holds only if the area under consideration is uniformly and uniformly varied throughout the consolidation process. If the area under consideration is not uniformly consolidated, the consolidation rate of the soil will no longer be controlled solely by the consolidation coefficient (cv), but will be determined jointly by the volumetric compressibility coefficient mv and the permeability coefficient k.

[0003] Accurate prediction of the degree of consolidation of soft clay foundations is particularly important. Terzaghi's one-dimensional consolidation algorithm is simple in form and has clear physical meaning of parameters. This algorithm has been adopted by my country's building foundation and fill foundation treatment codes.

[0004] Generally, silt has high compressibility. During the consolidation process, as the consolidation time increases, the consolidation state of the silt exhibits significant non-uniformity, affecting the average consolidation rate of the foundation and thus impacting the construction schedule and consolidation effect. Small-strain calculations tend to underestimate soil settlement, and current large-strain calculations are mostly based on the finite difference method or finite element method, which are quite cumbersome and pose significant difficulties for engineering applications.

[0005] Therefore, there is an urgent need for a large-strain consolidation algorithm that can cope with the characteristics of silt and accurately guide key engineering decisions such as the design of drainage board spacing and the determination of vacuum preloading time. Summary of the Invention

[0006] To address the shortcomings of existing strain consolidation calculation methods in terms of practicality and adaptability to the needs of horizontal vacuum dewatering of sludge, a large-strain consolidation algorithm, device, and medium for horizontal vacuum dewatering of sludge are proposed. The influence of non-uniform consolidation is incorporated into Terzaghi's one-dimensional theoretical consolidation analysis, and the consolidation coefficient is corrected using the governing equations based on virtual time steps and strain conditions, thereby achieving convenient and accurate consolidation calculation.

[0007] To achieve the above objectives, the first aspect of this invention proposes a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge, characterized in that the algorithm includes:

[0008] Step 1: Obtain the basic parameters of the constitutive relationship of the target soil through indoor consolidation experiments and permeability tests;

[0009] Step 2: Obtain the load conditions of the target soil by investigating the geological survey report and engineering design plan;

[0010] Step 3: Introduce a virtual time step and calculate the degree of consolidation by segmenting the time into increments;

[0011] Step 4: Establish a one-dimensional PHD consolidation model and derive the governing equations under constant strain conditions;

[0012] Step 5: Calculate the final degree of consolidation based on the virtual time step and governing equations.

[0013] Furthermore, the basic parameters of the constitutive relationship of the target soil described in step 1 include the soil layer thickness h, the initial void ratio e0, and the compression index C. c Initial permeability coefficient k0, vacuum pressure p, permeability constant C p Spacing between PHD and PHD.

[0014] Furthermore, the load conditions of the target soil in step 2 include the initial stress σ. a and final stress σ b .

[0015] Further, step 3 includes:

[0016] Step 3.1: Calculate the degree of consolidation U at the beginning of the i-th increment time using a step-by-step time increment method. j Assuming the degree of consolidation U j As shown in formula (1):

[0017] U j =f(H i )·g(i 0,g )·t j (1);

[0018] Among them, H i and i 0,g For t j The corresponding soil height and initial forced descent;

[0019] Step 3.2: At the j=m-1th... th With time increments of (m = 1, 2, ...), t m-1 The degree of consolidation at time U m-1 , m th The virtual time increment is expressed by formula (2):

[0020]

[0021] Using t m +Δt m To calculate the new degree of consolidation, H m and i0,m These are soil parameters, calculated from t m-1 ~t m The degree of consolidation increment ΔU m Thus, the degree of consolidation U is determined. m =U m-1 +ΔU m .

[0022] By gradually increasing the time increment and the virtual time increment Δt m The design incorporates the soil height H during large strain consolidation. i Dynamic changes, initial forced landing 0,m The time-varying nonlinear problem is decomposed into several linear time steps, avoiding the shortcomings of traditional global time calculations that cannot take into account the dynamic changes of parameters, and ensuring the degree of consolidation U in each time increment. j The calculations are more accurate.

[0023] Through U m =U m-1 +ΔU m The incremental calculation logic can calculate in real time based on the previous time t. m-1 The degree of consolidation is adjusted in subsequent calculations (such as H). m and i 0,m If the vacuum pressure or drainage conditions change during the project, the calculation can continue only by correcting the parameters within the corresponding time increment, without having to conduct the overall analysis again, thus improving the algorithm's adaptability to dynamic adjustments in the project.

[0024] 5. The method for calculating the degree of consolidation of a foundation based on the modified consolidation coefficient according to claim 1, characterized in that step 4 includes:

[0025] Step 4.1: Using Terzaghi's one-dimensional consolidation theory, a one-dimensional PHD consolidation model is established under constant strain conditions, as shown in formula (3):

[0026]

[0027] Among them, c v Where is the consolidation coefficient, and u is the excess pore water pressure;

[0028] Considering the boundary conditions shown in equations (4)-(6), the excess pore water pressure u is shown in equation (7), and the average pore water pressure is shown in equation (8):

[0029] u| t＝0 =0 (4);

[0030] u| z＝0 =-p (5);

[0031]

[0032] Among them, Z f is the vertical coordinate of the forward streamline at the top of the treatment zone, and i0 is the critical hydraulic gradient;

[0033]

[0034] in,

[0035] Consider boundary conditions Define C = -p + γ w ·i0·z f The vertical consolidation time factor Tv is shown in formula (9), and the settlement S t As shown in formula (10):

[0036]

[0037] In the formula, p0 is the initial effective stress, and c c It is the compression index, e0 is the void ratio, and H0 is the initial soil height.

[0038] Based on Terzaghi's theory, the horizontal dissipation path of pore water pressure under the action of a horizontal drainage board is accurately simulated by using formula (3) as the governing equation and boundary conditions (formulas 4-6).

[0039] A complete calculation system is formed that combines hydraulic characteristics (u), time characteristics (Tv), and deformation characteristics (St). This system can not only output the degree of consolidation but also directly obtain the settlement amount that is of concern in engineering, without the need to build an additional settlement calculation model, thus improving the practicality of the technology.

[0040] The streamline Z at the top of the processing zone in the boundary conditions f The definition can delineate the effective consolidation zone in silt (Z≤Z). f ) and unconsolidated region (Z>Z f This method accurately reflects the non-uniform characteristics of horizontal vacuum dehydration, where the consolidation near the drainage plate is sufficient and the consolidation in the far drainage plate is lagging, thus avoiding calculation errors caused by the traditional assumption of uniform consolidation.

[0041] Further, step 5 includes:

[0042] The final degree of consolidation is calculated using virtual time steps and governing equations, and the corrected one-dimensional degree of consolidation U of the foundation is calculated using equations (9) and (10). m As shown in formula (11):

[0043]

[0044] In the formula, T v denoted by t, where u is the pore water pressure at time t.

[0045] A second aspect of the present invention provides a computer device including a memory and a processor, the processor being configured to execute a computer program stored in the memory to implement a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge.

[0046] A third aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed, implements a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge.

[0047] The beneficial effects of the present invention through the above technical solution are as follows:

[0048] The algorithm of this invention decomposes the nonlinear problem of dynamic soil height change and time-varying initial forced settlement into linear time steps by introducing virtual time step piecewise incremental calculation; at the same time, it establishes a one-dimensional PHD consolidation model to define the seepage front Z. f It distinguishes between the effectively consolidated zone and the unconsolidated zone, realistically simulating the pore water pressure dissipation process under the action of a horizontal drainage board. It has high detection accuracy.

[0049] The algorithm system integrates soil constitutive parameters, engineering load conditions, and hydraulic characteristic parameters to form a complete calculation system of "excess pore water pressure - degree of consolidation - settlement - time factor". It can directly output key engineering indicators without the need for additional splicing of multiple models, solving the problem of computational fragmentation caused by the separation of physical quantities in traditional algorithms, and meeting the engineering needs for coupled analysis of "hydraulic-stress-deformation". Attached Figure Description

[0050] Figure 1 This is a flowchart of the steps of a large strain consolidation algorithm for horizontal vacuum dewatering of sludge according to the present invention;

[0051] Figure 2 This is a schematic diagram of the ITC incremental calculation method for a large strain consolidation algorithm for horizontal vacuum dewatering of sludge according to the present invention.

[0052] Figure 3 This is a schematic diagram of a model experiment and a physical example of a large strain consolidation algorithm for horizontal vacuum dewatering of sludge according to the present invention;

[0053] Figure 4 This invention relates to a large strain consolidation algorithm for horizontal vacuum dewatering of sludge, illustrating the pore water pressure changes at points P1, P2, and P3 in an experiment.

[0054] Figure 5 This is a graph showing the change in sedimentation over time during an experiment of a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to the present invention.

[0055] Figure 6This is a graph showing the change of settlement with logarithmic time in an experiment of a large strain consolidation algorithm for horizontal vacuum dewatering of sludge.

[0056] Figure 7 This is a schematic diagram of drainage data in an experiment of a large strain consolidation algorithm for horizontal vacuum dewatering of sludge.

[0057] Figure 8 This is a comparison chart of the settlement data monitored on-site and the settlement data calculated by the theoretical model in an experiment of a large strain consolidation algorithm for horizontal vacuum dewatering of sludge.

[0058] Figure 9 This is a comparison chart of the average pore water pressure measured in experiments and calculated by theoretical models in a large strain consolidation algorithm for horizontal vacuum dewatering of sludge. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0060] Example 1

[0061] like Figure 1-2 As shown, a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge is disclosed, the algorithm comprising:

[0062] Step 1: Obtain the basic parameters of the constitutive relationship of the target soil through indoor consolidation experiments and permeability tests;

[0063] Step 2: Obtain the load conditions of the target soil by investigating the geological survey report and engineering design plan;

[0064] Step 3: Introduce a virtual time step and calculate the degree of consolidation by segmenting the time into increments;

[0065] Step 4: Establish a one-dimensional PHD consolidation model and derive the governing equations under constant strain conditions;

[0066] Step 5: Calculate the final degree of consolidation based on the virtual time step and governing equations.

[0067] The basic parameters of the constitutive relationship of the target soil in step 1 include soil layer thickness h, initial void ratio e0, and compression index C. c Initial permeability coefficient k0, vacuum pressure p, permeability constant C p Spacing between PHD and PHD.

[0068] The load conditions of the target soil in step 2 include the initial stress σ a and final stress σ b .

[0069] Step 3 includes:

[0070] Step 3.1: Calculate the degree of consolidation U at the beginning of the i-th increment time using a step-by-step time increment method. j Assuming the degree of consolidation U j As shown in formula (1):

[0071] U j =f(H i )·g(i 0,g )·t j (1);

[0072] Among them, H i and i 0,g For t j The corresponding soil height and initial forced descent;

[0073] Step 3.2: At the j=m-1th... th With time increments of (m = 1, 2, ...), t m-1 The degree of consolidation at time U m-1 , m th The virtual time increment is expressed by formula (2):

[0074]

[0075] Using t m +Δt m To calculate the new degree of consolidation, H m and i 0,m These are soil parameters, calculated from t m-1 ~t m The degree of consolidation increment ΔU m Thus, the degree of consolidation U is determined. m =U m-1 +ΔU m .

[0076] Step 4 includes:

[0077] Step 4.1: Using Terzaghi's one-dimensional consolidation theory, a one-dimensional PHD consolidation model is established under constant strain conditions, as shown in formula (3):

[0078]

[0079] Among them, c v Where is the consolidation coefficient, and u is the excess pore water pressure;

[0080] Considering the boundary conditions shown in equations (4)-(6), the excess pore water pressure u is shown in equation (7), and the average pore water pressure is shown in equation (8):

[0081]

[0082] Among them, Zf is the vertical coordinate of the forward streamline at the top of the treatment zone, and i0 is the critical hydraulic gradient;

[0083]

[0084] in,

[0085] Consider boundary conditions Define C = -p + γ w ·i0·z f The vertical consolidation time factor Tv is shown in formula (9), and the settlement S t As shown in formula (10):

[0086]

[0087] In the formula, p0 is the initial effective stress, and c c It is the compression index, e0 is the void ratio, and H0 is the initial soil height.

[0088] Step 5 includes:

[0089] The final degree of consolidation is calculated using virtual time steps and governing equations, and the corrected one-dimensional degree of consolidation U of the foundation is calculated using equations (9) and (10). m As shown in formula (11):

[0090]

[0091] In the formula, T v denoted by t, where u is the pore water pressure at time t.

[0092] Example 2

[0093] Based on Embodiment 1, the present invention also provides a computer device, which may include a processor, a memory, and may further include a communication interface and a communication bus, etc. The processor, memory, and communication interface communicate with each other through the communication bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer program instructions. The internal memory provides an environment for the operation of the operating system and computer program instructions in the non-volatile storage medium. The communication interface of the above device is used for wired or wireless communication with an external terminal. Wireless communication can be achieved through WiFi, carrier networks, NFC (Near Field Communication), or other technologies. The memory stores computer program instructions that cause the processor to execute the above-described method.

[0094] Example 3

[0095] Based on Embodiment 1, the present invention also provides a computer-readable storage medium. Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing related hardware through computer program instructions. These computer program instructions can be stored in a non-volatile computer-readable storage medium. When executed, these computer program instructions can implement the above-described large-strain consolidation algorithm for horizontal vacuum dewatering of sludge. Any references to memory, storage, databases, or other media used in the embodiments provided by the present invention can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory.

[0096] Example 4

[0097] Based on the large strain consolidation algorithm for horizontal vacuum dewatering of sludge in Embodiment 1 of this application, the following comparative experiments were conducted to verify the effectiveness of the present invention.

[0098] In this experiment, dredged marine clay (silt) was used. The core physical and mechanical parameters were determined by geotechnical testing, with the initial stress σ being... a The basic parameters of the constitutive relation of the target soil with a pressure of 2.0 kPa and a water content of 75.3% are as follows:

[0099] Compression index C c The initial porosity is 0.56, the initial void ratio e0 is 2.07, the initial permeability coefficient k0 is 0.00027 m / day, and the permeability constant C is... p It is 1.1.

[0100] A 420mm×150mm×610mm transparent acrylic model box (open at the top without a membrane) is used, with a horizontal drainage system (PHD) at the bottom, along with a vacuum pump (applying a vacuum pressure of -65kPa), a suction flask, an electronic scale, and a pore water pressure gauge. A schematic diagram and a photograph of the actual device are shown below. Figure 3 As shown, Figure 3 (a) is a schematic diagram of the device. Figure 3 (b) is a picture of the actual object.

[0101] Monitoring indicators:

[0102] Pore ​​water pressure: As shown in the figure: real-time monitoring at three points, namely the upper part (P1), the middle part (P2), and the near-drain body (P3), is used to calculate the average pore water pressure and degree of consolidation;

[0103] Settlement: Simultaneous measurement at three points (left, middle, and right) is used to back-calculate the degree of consolidation based on the settlement amount, and the calculation results are cross-verified.

[0104] Discharge volume: collected by suction flask and measured by electronic scale to help verify the evolution law of consolidation degree;

[0105] Experiment duration: 1096 hours, covering the entire process from initial 0 to stable state of consolidation.

[0106] Based on the incremental consolidation formula proposed in this application, the permeability coefficient and consolidation coefficient c are dynamically updated using the virtual time concept (ITC). v The degree of consolidation is calculated in increments over time periods, such as the initial forced landing i0, and the total degree of consolidation is obtained by accumulating these increments.

[0107] like Figure 4 As shown, the pressure at point P3 drops by 40 kPa and stabilizes within 250 hours. The pressure at point P2 begins to decrease after 200 hours, and the pressure at point P1 decreases slowly after 800 hours. The average pore water pressure at each time point is calculated based on this.

[0108] like Figure 5 and 6 As shown, the settlement develops in four stages, with the final settlement at the right, middle, and left points being 7.38 cm, 6.99 cm, and 6.90 cm, respectively. The degree of consolidation is calculated by correlating the changes in the void ratio.

[0109] like Figure 7 As shown, the drainage data exhibits a three-stage change: slow, accelerated, and stable, consistent with the increasing trend of consolidation degree.

[0110] This demonstrates that the method of the present invention conforms to the solidification process. The present invention achieves accurate simulation of the solidification process by dynamically updating key parameters, and has good application effect.

[0111] The method of this invention was compared with that of Zhou, Y., Yin, B., Wang, P., Ge, X., Zhao, B., 2024. "Pilot test and consolidation theory of marinated dredged slurry using the membrane-free horizontal-vacuum method." Ocean Eng. 293, 116650., and the existing Darcy seepage large strain model. The comparison results are as follows: Figure 8 and 9 As shown:

[0112] in, Figure 8To compare and analyze the curves plotted from the settlement data obtained from the experimental site monitoring with the settlement curves calculated by the theoretical model, “Proposedmodel” is the settlement curve of this application, “Zhou et al. (2024)” is the settlement curve obtained by the method of “Field test and consolidation theory of marine dredging mud treatment by membrane-free horizontal vacuum method”, the blue circle is the settlement curve plotted from the experimental site data, and “Proposedmodel-2” is the settlement curve of the existing Darcy seepage large strain model.

[0113] Figure 9 For the comparison of measured and calculated average pore water pressure, “Proposedmodel” is the average pore water pressure of this application, “Proposedmodel-2” is the pore water pressure of the existing Darcy seepage large strain model, “Monitoringdata” is the measured data, and “Zhou et al. (2024)” is the pore water pressure obtained by the method of “Field test and consolidation theory of marine dredging mud treatment by membrane-free horizontal vacuum method”.

[0114] The physical meaning of the degree of consolidation is "the degree to which pore water pressure in the soil dissipates", and the dissipation of pore water pressure is directly related to soil compression (settlement).

[0115] Therefore, through Figure 8 and Figure 9 It can be seen that this application closely matches the measured data, and the trend is consistent with the measured data. It has better calculation results than "Field Test and Consolidation Theory of Marine Dredging Mud Treatment by Membrane-Free Horizontal Vacuum Method" and Darcy's large strain model.

[0116] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included within the scope of the present invention.

Claims

1. A large-strain consolidation algorithm for horizontal vacuum dewatering of sludge, characterized in that, The algorithm includes: Step 1: Obtain the basic parameters of the constitutive relationship of the target soil through indoor consolidation experiments and permeability tests; Step 2: Obtain the load conditions of the target soil by investigating the geological survey report and engineering design plan; Step 3: Introduce a virtual time step and calculate the degree of consolidation by segmenting the time into increments; Step 4: Establish a one-dimensional PHD consolidation model and derive the governing equations under constant strain conditions; Step 5: Calculate the final degree of consolidation based on the virtual time step and governing equations.

2. The method for a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to claim 1, characterized in that, The basic parameters of the constitutive relationship of the target soil in step 1 include soil layer thickness h, initial void ratio e0, and compression index C. c Initial permeability coefficient k0, vacuum pressure p, permeability constant C p Spacing between PHD and PHD.

3. The method for a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to claim 1, characterized in that, The load conditions of the target soil in step 2 include the initial stress σ a and final stress σ b .

4. The method for a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to claim 1, characterized in that, Step 3 includes: Step 3.1: Calculate the degree of consolidation U at the beginning of the i-th increment time using a step-by-step time increment method. j Assuming the degree of consolidation U j As shown in formula (1): U j =f(H i )·g(i 0,g )·t j (1); Among them, H i and i 0,g For t j The corresponding soil height and initial forced descent; Step 3.2: At the j=m-1th... th With time increments of (m = 1, 2, ...), t m-1 The degree of consolidation at time U m-1 , m th The virtual time increment is expressed by formula (2): Using t m +Δt m To calculate the new degree of consolidation, H m and i 0,m These are soil parameters, calculated from t m-1 ~t m The degree of consolidation increment ΔU m Thus, the degree of consolidation U is determined. m =U m-1 +ΔU m .

5. The method for a large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to claim 1, characterized in that, Step 4 includes: Step 4.1: Using Terzaghi's one-dimensional consolidation theory, a one-dimensional PHD consolidation model is established under constant strain conditions, as shown in formula (3): Among them, c v Where u is the consolidation coefficient and u is the excess pore water pressure. Considering the boundary conditions shown in equations (4)-(6), the excess pore water pressure u is shown in equation (7), and the average pore water pressure is shown in equation (8): u| t＝0 ＝0 (4)； in| z＝0 =-p (5); Among them, Z f is the vertical coordinate of the forward streamline at the top of the treatment zone, and i0 is the critical hydraulic gradient; in, Consider boundary conditions Define C = -p + γ w ·i0·z f The vertical consolidation time factor Tv is shown in formula (9), and the settlement S t As shown in formula (10): In the formula, p0 is the initial effective stress, and c c It is the compression index, e0 is the void ratio, and H0 is the initial soil height.

6. The large-strain consolidation algorithm for horizontal vacuum dewatering of sludge according to claim 1, characterized in that, Step 5 includes: The final degree of consolidation is calculated using virtual time steps and governing equations, and the corrected one-dimensional degree of consolidation U of the foundation is calculated using equations (9) and (10). m As shown in formula (11): In the formula, T v denoted by t, where u is the pore water pressure at time t.

7. A computer device, characterized in that, It includes a memory and a processor, the processor being configured to execute a computer program stored in the memory to implement the method according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method according to any one of claims 1 to 7.

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