Method for monitoring clogging effect in real time

Abstract

The invention relates to a real-time monitoring method for a clogging effect, in particular to the technical field of dredged sludge vacuum preloading, and the real-time monitoring method for the clogging effect comprises the following steps: arranging a plurality of groups of pore water pressure sensor arrays around a plastic drainage plate along the depth direction; wherein each group of pore water pressure sensor array comprises at least three sensors which are distributed along the radial direction and are used for acquiring hyperstatic pore water pressure data at different radial positions and depths in real time; and based on the hyperstatic pore water pressure data and a preset permeability coefficient attenuation model, calculating the real-time radius rs and permeability coefficient distribution ks (r) of the clogging area, and completing real-time monitoring data collection. By arranging the multi-dimensional pore water pressure sensor array and combining the permeability coefficient attenuation model to invert the radius and permeability coefficient distribution of the clogging area in real time, the vacuum pressure is dynamically adjusted, the consolidation rate is stabilized at the preset threshold value, the construction period is shortened, and the equipment utilization rate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum preloading of dredged sludge, and in particular to a real-time monitoring method for siltation effect. Background Art

[0002] Existing vacuum preloading technologies for dredged sludge mostly rely on empirical methods, using vacuum pumps to continuously extract pore water to reduce the water content of the sludge. However, differences in the physical and permeability properties of sludge lead to insufficient adaptability of standardized processes, which can easily lead to waste of resources and unstable consolidation effects. Traditional methods lack dynamic monitoring of clogging effects and are unable to correct vacuum pressure and permeability parameters in real time, resulting in a significant decrease in consolidation rate as the radius of the clogging area increases. The mathematical model does not consider the nonlinear attenuation of the permeability coefficient along the radial direction and depth. In addition, the sludge conditioning process mostly uses a single material, which has limited improvement in the permeability coefficient and makes it difficult to synergistically optimize the consolidation process. The above defects seriously restrict the efficiency and cost control of dredging projects. Summary of the Invention

[0003] The main purpose of this invention is to propose a real-time monitoring method for siltation effect, which aims to synergistically optimize the dredged silt consolidation process and optimize engineering efficiency and cost control.

[0004] To achieve the above-mentioned purpose, the present invention proposes a real-time monitoring method for clogging effect, which comprises:

[0005] Multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board along the depth direction; wherein each group of the pore water pressure sensor array includes at least three sensors distributed along the radial direction, which are used to collect excess pore water pressure data at different radial positions and depths in real time;

[0006] Based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the siltation area is calculated. s and permeability coefficient distribution k s (r), complete the real-time monitoring data collection; among them, the permeability coefficient attenuation model is:

[0007]

[0008] In one embodiment, the step of arranging multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction includes:

[0009] A group of the pore water pressure sensor array is arranged every 0.5m along the depth direction, and the distance between two radially adjacent sensors in each group of the pore water pressure sensor array is 0.2rh to 0.5rh, where rh is the radius of the influence area of ​​the plastic drainage board; the sensor data sampling frequency is not less than 1 time / minute, and is uploaded to the control terminal in real time through the wireless transmission module.

[0010] In one embodiment, multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board in a depth direction; wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed in a radial direction for real-time acquisition of excess pore water pressure data at different radial positions and depths. Before the step of:

[0011] In the initial stage of vacuum preloading, tracers are injected into the dredged sludge, and the diffusion rate of the tracer concentration is monitored by sensors to invert the initial permeability coefficient k0.

[0012] In one embodiment, the real-time radius r of the clogging area is calculated based on the excess pore water pressure data and the preset permeability coefficient attenuation model. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises:

[0013] Calculate the average degree of consolidation of dredged silt;

[0014] adjusting the vacuum pressure according to the average degree of consolidation of the dredged sludge;

[0015] If the average degree of consolidation of the dredged sludge is lower than a preset threshold, increasing the vacuum pressure;

[0016] If the average degree of consolidation of the dredged sludge is higher than a preset threshold, the vacuum pressure is reduced.

[0017] In one embodiment, the step of calculating the average degree of consolidation of the dredged sludge comprises:

[0018] According to the formula Calculate the degree of consolidation of each layer in real time.

[0019] In one embodiment, multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board in a depth direction; wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed in a radial direction for real-time acquisition of excess pore water pressure data at different radial positions and depths. Before the step of:

[0020] Add a conditioning agent to the dredged sludge, wherein the conditioning agent is composed of rice husk ash, carbide slag and polyaluminium chloride in a mass ratio of 60-80:20-30:5-10, and the addition amount is 3% to 5% of the dry mass of the dredged sludge; after addition, the conditioning agent is uniformly mixed through a stirring device to increase the permeability coefficient k of the non-clogging area. h To 1.5 to 2 times the initial value.

[0021] In one embodiment, the particle size distribution of the rice husk ash satisfies the following requirements: more than 90% of the particles have a particle size of less than 0.075 mm, and the loss on ignition does not exceed 8%; the CaO content of the carbide slag is ≥ 65%, and the specific surface area is 400-600 m 2 / kg.

[0022] In one embodiment, based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the clogging area is calculated. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises:

[0023] When rh>0.6, the warning signal is triggered and the high-pressure water jet device is started to flush the PVD surface blockage layer at a pressure of 5-10 MPa, and the flushing time is 10-15 minutes / cycle.

[0024] In one embodiment, the water flow of the high-pressure water jet device contains 0.1% to 0.3% by mass of sodium lauryl sulfate, and the water temperature is controlled at 40 to 50°C.

[0025] The technical solution of the present invention deploys a multi-dimensional pore water pressure sensor array, combines the permeability coefficient attenuation model to invert the radius of the blockage area and the permeability coefficient distribution in real time, and dynamically adjusts the vacuum pressure to stabilize the consolidation rate at a preset threshold, shortening the construction period by 30% to 40%; adopts rice husk ash-calcium carbide slag-polyaluminum chloride composite tempering agent (mass fraction 60-80:20-30:5-10) to synergistically improve the permeability coefficient of the non-blockage area to 1.5 to 2 times the initial value, and reduces the consolidation time to meet the standard by 50%; sets the radius threshold of the blockage area to link high-pressure water jet flushing, combines surfactants and temperature control to enhance blockage stripping, reduces the risk of project interruption by 80%, and increases equipment utilization by 25%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0027] Figure 1 A schematic flow chart of an embodiment of a method for real-time monitoring of clogging effects provided by the present invention;

[0028] Figure 2 The vacuum preloading calculation model of the present invention is an example;

[0029] Figure 3This is the result of the influence of the maximum radius of the clogging area on the consolidation degree according to the example of the present invention;

[0030] Figure 4 This is the result of the influence of the attenuation coefficient of the siltation area on the consolidation degree according to the example of the present invention;

[0031] Figure 5 This is the result of the effect of the clogging coefficient on the consolidation degree according to the example of the present invention;

[0032] Figure 6 The results of the influence of the maximum volume compression coefficient of dredged sludge on the degree of consolidation are given in the example of the present invention;

[0033] Figure 7 This is the result of the influence of the radius of the plastic drainage board on the consolidation degree according to the example of the present invention;

[0034] Figure 8 This is the result of the influence of the permeability coefficient of the non-clogging area of ​​dredged silt on the consolidation degree according to the example of the present invention.

[0035] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] See also Figure 1 In one embodiment of the present invention, the method for real-time monitoring of clogging effects includes:

[0040] Step S10: Arrange multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction; wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed along the radial direction, and is used to collect excess pore water pressure data at different radial positions and depths in real time;

[0041] Step S20: Calculate the real-time radius r of the clogging area based on the excess pore water pressure data and the preset permeability coefficient attenuation model. s and permeability coefficient distribution k s (r), complete the real-time monitoring data collection; among them, the permeability coefficient attenuation model is:

[0042]

[0043] Specifically, multiple pore water pressure sensor arrays are arranged along the depth direction around the plastic drainage board (PVD). Each array contains at least three sensors distributed along the radial direction, which are used to collect excess pore water pressure data at different radial positions and depths in real time. Based on the excess pore water pressure data, combined with a preset permeability attenuation model, the real-time radius rs(z,t) of the siltation area and the permeability distribution ks(r,z,t) are calculated. The permeability attenuation model is:

[0044]

[0045] Substitute rs(z, t) and ks(r, z, t) into the vacuum preloading radial consolidation equation to calculate the average consolidation degree of dredged sludge U(z, t) in real time, and dynamically adjust the vacuum negative pressure value p0(t) according to U(z, t). The vacuum preloading radial consolidation equation is:

[0046]

[0047] Real-time excess pore water pressure data is acquired through a sensor array, and the parameters of the siltation zone are dynamically inverted using the permeability coefficient attenuation model. The consolidation equation is used to close the loop and control the vacuum pressure, thus solving the resource waste problem caused by the empirical method.

[0048] In the technical solution provided by the present invention, a multi-dimensional pore water pressure sensor array is arranged, and the permeability coefficient attenuation model is combined to invert the radius of the blockage area and the permeability coefficient distribution in real time, and the vacuum pressure is dynamically adjusted to stabilize the consolidation rate at a preset threshold value, thereby shortening the construction period by 30% to 40%; a rice husk ash-calcium carbide slag-polyaluminum chloride composite tempering agent (mass fraction 60-80:20-30:5-10) is used to synergistically improve the permeability coefficient of the non-blockage area to 1.5 to 2 times the initial value, and the consolidation time is reduced by 50%; the radius threshold of the blockage area is set to link high-pressure water jet flushing, and the surfactant and temperature control are combined to enhance the blockage stripping, thereby reducing the risk of project interruption by 80% and increasing the equipment utilization rate by 25%.

[0049] In one embodiment, the step of arranging multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction includes:

[0050] A group of the pore water pressure sensor array is arranged every 0.5m along the depth direction, and the distance between two radially adjacent sensors in each group of the pore water pressure sensor array is 0.2rh to 0.5rh, where rh is the radius of the influence area of ​​the plastic drainage board; the sensor data sampling frequency is not less than 1 time / minute, and is uploaded to the control terminal in real time through the wireless transmission module.

[0051] Specifically, the pore water pressure sensor array is spaced to meet the following requirements: one group is placed every 0.5 m along the depth direction, with radial sensor spacing within each group ranging from 0.2rh to 0.5rh, where rh is the radius of the plastic drainage panel's impact zone. Sensor data is sampled at a frequency of no less than once per minute and uploaded to the control terminal in real time via a wireless transmission module. The sensor density and sampling frequency are optimized to ensure coverage of the depth and radial variations of dredged silt, avoiding model errors caused by local data loss.

[0052] In one embodiment, multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board in a depth direction; wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed in a radial direction for real-time acquisition of excess pore water pressure data at different radial positions and depths. Before the step of:

[0053] In the initial stage of vacuum preloading, tracers are injected into the dredged sludge, and the diffusion rate of the tracer concentration is monitored by sensors to invert the initial permeability coefficient k0.

[0054] In addition, the parameters of the permeability attenuation model are calibrated by the following steps:

[0055] During the initial vacuum preloading phase, tracers are injected into the dredged sludge. Sensors monitor the tracer concentration and diffusion rate, and the initial permeability coefficients kh(0) and k0(0) are inverted. Initial parameters are calibrated with tracers, and the permeability coefficients are dynamically corrected using Darcy's law to improve model accuracy.

[0056] In one embodiment, the real-time radius r of the clogging area is calculated based on the excess pore water pressure data and the preset permeability coefficient attenuation model. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises:

[0057] Calculate the average degree of consolidation of dredged silt;

[0058] adjusting the vacuum pressure according to the average degree of consolidation of the dredged sludge;

[0059] If the average degree of consolidation of the dredged sludge is lower than a preset threshold, increasing the vacuum pressure;

[0060] If the average degree of consolidation of the dredged sludge is higher than a preset threshold, the vacuum pressure is reduced.

[0061] Specifically, if U(z,t) is lower than a preset threshold, the vacuum pressure is increased, where 0.05β=0.05~0.20.2 is the gain coefficient;

[0062] If U(z,t) exceeds a preset threshold, the vacuum pressure is reduced, where 0.03γ = 0.03 to 0.10.1 is the attenuation coefficient. A proportional feedback control algorithm is used to avoid soil structural damage caused by sudden changes in vacuum pressure and achieve a smooth optimization of the consolidation rate.

[0063] In one embodiment, the step of calculating the average degree of consolidation of the dredged sludge comprises:

[0064] According to the formula Calculate the degree of consolidation of each layer in real time.

[0065] In one embodiment, multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board in a depth direction; wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed in a radial direction for real-time acquisition of excess pore water pressure data at different radial positions and depths. Before the step of:

[0066] Add a conditioning agent to the dredged sludge, wherein the conditioning agent is composed of rice husk ash, carbide slag and polyaluminium chloride in a mass ratio of 60-80:20-30:5-10, and the addition amount is 3% to 5% of the dry mass of the dredged sludge; after addition, the conditioning agent is uniformly mixed through a stirring device to increase the permeability coefficient k of the non-clogging area. h To 1.5 to 2 times the initial value.

[0067] Specifically, a conditioning agent is added to the dredged sludge. The conditioning agent is composed of rice husk ash, calcium carbide slag, and polyaluminium chloride in a ratio of 60-80 parts by weight: 20-30 parts by weight: 5-10 parts by weight. The addition amount is 3% to 5% of the dry weight of the dredged sludge. After addition, the sludge is evenly mixed using a stirring device to increase the permeability coefficient kh(t) in the non-clogging area to 1.5 to 2 times the initial value. By improving the permeability of the sludge with a specific conditioning agent ratio, and in conjunction with the monitoring and control strategy, the consolidation efficiency is significantly improved.

[0068] In one embodiment, the particle size distribution of the rice husk ash satisfies the following requirements: more than 90% of the particles have a particle size of less than 0.075 mm, and the loss on ignition does not exceed 8%; the CaO content of the carbide slag is ≥ 65%, and the specific surface area is 400-600 m 2 / kg.

[0069] Specifically, the key parameters of the conditioning agent are defined to ensure sufficient physical and chemical reaction between the conditioning agent and the sludge particles and to prevent impurities from interfering with the permeability enhancement effect.

[0070] In one embodiment, based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the clogging area is calculated. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises:

[0071] When rh>0.6, the warning signal is triggered and the high-pressure water jet device is started to flush the PVD surface blockage layer at a pressure of 5-10 MPa, and the flushing time is 10-15 minutes / cycle.

[0072] In one embodiment, the water flow of the high-pressure water jet device contains 0.1% to 0.3% sodium lauryl sulfate by mass, and the water temperature is controlled at 40-50°C. By setting a radius threshold for the blockage area and activating an emergency treatment device, consolidation stagnation caused by severe blockage can be prevented, ensuring project continuity. The addition of surfactants and controlled water temperature enhance the flushing fluid's ability to remove fine particles of blockage, reducing flushing times and energy consumption.

[0073] In one embodiment, when rh>0.6, the steps of triggering an early warning signal and starting a high-pressure water jet device to flush the PVD surface blockage layer at a pressure of 5 to 10 MPa for 10 to 15 minutes per cycle include:

[0074] After the high-pressure water jet flushing, the real-time radius r of the clogging area is recalculated. s , until r s ≤0.4rh.

[0075] Specifically, after high-pressure water jet flushing, rs(z, t) and U(z, t) are recalculated. If U(z, t) returns to above 90% of the preset threshold, flushing is stopped and the current vacuum pressure is maintained. If it fails to meet the threshold, flushing is repeated until the radius of the blocked area, rs(z, t), is ≤ 0.4rh. This closed-loop verification of flushing effectiveness avoids resource waste caused by excessive flushing and ensures project efficiency.

[0076] In some exemplary embodiments, the method of the present invention may be performed as follows:

[0077] Establish as Figure 2 The vacuum preloading calculation theoretical model considering the clogging effect is shown in the figure. The vacuum negative pressure applied on the top of the plastic drainage board (hereinafter referred to as PVD) is p0, which decays linearly along the depth with a decay coefficient of k1. The vacuum negative pressure at the end position is p0k1. The treatment depth of PVD, that is, the thickness of dredged silt, is H. The PVD permeability coefficient, equivalent drainage radius and influence zone radius are k respectively. w 、r w and r h Under the action of vacuum pressure, the pore water in the dredged silt within the PVD influence range will seep radially toward the PVD. During this process, fine particles will also migrate toward the PVD under the action of vacuum pressure, thus forming a clogging area around the PVD. Due to the vertical attenuation of the vacuum degree, the range of the clogging area formed also decreases with depth. For simplicity, it is assumed that the radius of the clogging area is determined by the surface position k. smax Linearly decreases to k2k at the end position smax , the attenuation coefficient is k2, and the radius of the clogging area at any depth is r s (z). Due to the existence of the clogging effect, the radial permeability coefficient of the clogging area is smaller than that of the non-clogging area, and the closer to the PVD, the smaller the permeability coefficient. The permeability coefficient at any position is expressed as k s (r) indicates that the outer area of ​​the siltation area is the non-siltation area, and the radial permeability coefficient is k h .

[0078] The following basic assumptions are made during the analysis: Assumption 1: The soil has no lateral deformation and the vertical deformation at any point at the same depth is equal;

[0079] Assumption 2: Only radial seepage is considered, and the seepage under negative pressure conditions obeys Darcy's law;

[0080] Assumption 3: The area below the calculation depth and outside the influence radius of the vertical drainage board is impermeable;

[0081] Assumption 4: The vertical drainage board, the silted area, and the non-silted area have the same properties except for the different permeability coefficients;

[0082] Assumption 5: The vacuum degree decays linearly along the vertical direction, and the range of the blockage area decreases linearly along the depth.

[0083] Based on the above assumptions, the radial consolidation equation of vacuum preloading of dredged silt is expressed as:

[0084]

[0085] Where: ε and m v represent the vertical strain and volume compressibility of dredged silt, respectively; is the average excess pore pressure at any depth within the PVD influence range when only radial seepage is considered, and t is time.

[0086] according to Figure 2 , the vacuum degree at any depth can be expressed as:

[0087]

[0088] The radius of the clogging area at any depth can be expressed as:

[0089]

[0090] Assume that the permeability coefficient of the silted area is determined by k h The permeability coefficient at any position in the clogging area can be expressed as follows:

[0091]

[0092] Where: k0 is the minimum value of the permeability coefficient in the silted area;

[0093] The boundary conditions are as follows:

[0094] At the outer boundary of the PVD affected area, there are:

[0095]

[0096] The excess pore pressure on the contact surface between PVD and the clogging area is equal, that is:

[0097]

[0098] The excess pore pressure on the contact surface between the blocked area and the non-blocked area is equal, that is:

[0099]

[0100] Where: u w 、u s (r,z) and u h (r,z) represent PVD, excess pore pressure in the blocked area and the non-blocked area, respectively.

[0101] On top of the PVD:

[0102] u w | z＝0 =-p0

[0103] On the PVD bottom:

[0104]

[0105] In some specific implementation processes, Darcy's law shows that the radial seepage rate through a cylindrical surface with a radius of r and a thickness of dz in time dt is:

[0106]

[0107] Where: dQ r is the radial seepage rate of the soil, k is the permeability coefficient. It should be pointed out that k here is a general term, and the permeability coefficients at different locations in the silted area and the non-silted area are different. w is the soil mass, u is the excess pore water pressure on the cylindrical surface, r w ≤r≤r h .

[0108] In the time dt, the radius is r to r h , the volume change of soil with thickness dz is:

[0109]

[0110] According to the equality of radial seepage rate and soil volume change, we can get:

[0111]

[0112] For r w ≤r≤r s (z) The clogging area within the range, Eq. It can be written as:

[0113]

[0114] And for r s (z)≤r≤r h In the non-blocked area within the range, equation It can be written as:

[0115]

[0116] On the contact surface between PVD and the blocked area, r = r w At , the amount of water that seeps into the PVD through the cylindrical surface with a thickness of dz within the time dt is:

[0117]

[0118] The upward water flow increment of PVD within this thickness range can be expressed as:

[0119]

[0120] Where: q w It is the water flow capacity of PVD.

[0121] Since the amount of water seeping from the soil into the PVD is equal to the upward flow increment of the PVD, then:

[0122]

[0123] From the equation and boundary condition equations and The excess pore water pressure at the interface between the siltation area and the PVD can be obtained as:

[0124]

[0125] Where: is the well diameter ratio.

[0126] Pair equation Integrating both sides, we can get:

[0127]

[0128] Solving equations Combined with the equation We can get:

[0129]

[0130] Similarly, for equation Integrating both sides, we can get:

[0131]

[0132] Solving equations Combined with the equation and We can get:

[0133]

[0134] The average excess pore water pressure at a certain depth in dredged silt can be expressed as:

[0135]

[0136] Put the equation

[0137] and,

[0138]

[0139] Substituting into the equation

[0140] Because n 2 is relatively large, so for simplicity, ignoring high-order terms, μ can be approximately expressed as:

[0141]

[0142] According to the equation It can be further written as follows:

[0143]

[0144] Where: T h is the time factor, which can be expressed as:

[0145]

[0146] Furthermore, the average radial consolidation degree can be obtained as:

[0147]

[0148] Where: u0, u t and u ∞ Corresponding to the initial moment, moment t and infinite moment respectively value.

[0149] The overall average consolidation degree U of dredged sludge within the PVD treatment depth range T It can be expressed as:

[0150]

[0151] The influence of the maximum radius of the siltation area on the consolidation degree of soil is as follows: Figure 3As shown in the figure, after vacuum negative pressure is applied, the degree of consolidation of the soil gradually increases with time, and the rate of increase gradually slows, indicating that the soil consolidation rate is gradually decreasing. The permeability coefficient of the siltation zone formed around the PVD during vacuum preloading of dredged sludge is significantly lower than that of the surrounding non-siltation zone, resulting in a slower pore water seepage rate. Therefore, as the maximum radius of the siltation zone increases, the degree of consolidation of the soil decreases at the same time, indicating that the soil consolidation rate is gradually slowing down. In addition, in the early stages of consolidation, the slope of the consolidation curve decreases significantly with the increase of the maximum radius of the siltation zone, indicating that the influence of the maximum radius of the siltation zone on the soil consolidation rate is more obvious in the early stages of consolidation. For example, at a consolidation time of 25 days, the corresponding consolidation degrees for an increase in the maximum siltation zone radius from 5 cm to 15 cm are 59.91%, 42.46%, 33.43%, 27.91%, and 24.16%, respectively. When the consolidation time is 100 days, the consolidation degree corresponding to the maximum siltation area radius of 5 cm is 97.32%, and the soil has basically completed consolidation. At this time, the consolidation degree corresponding to the maximum siltation area radius of 15 cm is only 66.56%, indicating that the siltation effect during the vacuum preloading process of the dredged silt site will significantly affect the treatment effect. Appropriate measures should be taken in actual projects to minimize the siltation effect.

[0152] The influence of the attenuation coefficient of the siltation area on the consolidation degree of soil is as follows: Figure 4 As shown, an attenuation coefficient of 1 means that the radius of the bottom and top of the siltation zone is the same. As the attenuation coefficient of the siltation zone increases, the corresponding degree of consolidation at the same time gradually decreases. In the early stages of consolidation, the attenuation coefficient has little effect on the degree of consolidation of the soil. As time goes by, the influence of the attenuation coefficient of the siltation zone gradually becomes more significant. When the consolidation time is 100 days, as the attenuation coefficient increases from 0.2 to 1, the degree of consolidation decreases from 89.37% to 72.52%. The larger the attenuation coefficient, the smaller the difference between the minimum and maximum radii of the siltation zone. In other words, the larger the average radius of the entire siltation zone, the greater the impact on soil consolidation.

[0153] The influence of siltation coefficient on soil consolidation degree is as follows: Figure 5 As shown in the figure, the soil consolidation curves for different siltation coefficients show similar trends over time. However, as the siltation coefficient increases, the soil consolidation decreases over the same period, but the rate of decrease gradually slows. For example, at a consolidation time of 100 days, the consolidation degrees are 84.76%, 80.05%, 75.41%, 72.80%, and 71.01%, respectively, as the siltation coefficient increases from 50 to 400. This is because as the siltation coefficient increases, the permeability coefficient of the silted area decreases, which slows the dissipation of excess pore water pressure in the silted area and reduces the consolidation rate.

[0154] The effect of dredged silt volume compression coefficient on soil consolidation degree is as follows: Figure 6As shown in the figure, as the volume compression coefficient of dredged silt increases, the consolidation degree of the soil gradually decreases at the same time, and the reduction rate gradually decreases in the early stage of consolidation, while the reduction rate gradually increases in the later stage of consolidation. This shows that as the volume compression coefficient increases, the consolidation rate of dredged silt gradually decreases, and the reduction degree is more obvious in the early stage of consolidation.

[0155] The influence of PVD influence radius on soil consolidation degree is as follows: Figure 7 As shown. The smaller the PVD influence radius, the denser the PVD layout. Correspondingly, the greater the slope of the consolidation curve in the initial consolidation stage, the faster the consolidation speed. For example, when the influence radius is 0.3m, the consolidation degree reaches 99.19% after 100 days, and the consolidation is completed. At this time, the consolidation degree corresponding to the influence radius of 0.7m is 54.44%, and the difference between the two is significant. Therefore, in actual engineering, the consolidation speed can be increased by appropriately reducing the spacing of PVD. In addition, at this moment, the consolidation degree corresponding to the influence radius of 0.4m has also reached 92.56%, and the treatment effect is not much different from that of the influence radius of 0.3m. Therefore, from the perspective of engineering cost, PVD should not be arranged too densely.

[0156] The effect of permeability coefficient of non-clogging area of ​​dredged silt on soil consolidation degree is as follows: Figure 8 As shown in the figure, as the permeability coefficient of the dredged silt in the non-clogging area increases, the soil consolidation rate increases significantly, but the increase gradually slows down. For example, after 100 days of consolidation, when the permeability coefficient increases from 2.5×10-9 m / s to 1.25×10-8 m / s, the soil consolidation degrees are 33.23%, 55.39%, 70.18%, 80.05%, and 98.19%, respectively. According to the analysis results, adding an appropriate amount of pollution-free ionic salts to the dredged silt during the dredging process to condition the silt and increase its permeability coefficient is of great significance for accelerating the vacuum preloading process and saving construction time and costs.

[0157] According to the above examples and in combination Figures 2 to 8In the demonstrative examples of the present invention, it was shown that the clogging effect significantly affects the consolidation rate of dredged sludge vacuum preloading. As the maximum radius of the clogging zone and the attenuation coefficient of the clogging zone increase, the clogging zone expands and the soil consolidation rate decreases. Therefore, the impact of the clogging effect should be considered in practical projects. A larger clogging coefficient results in a smaller permeability coefficient in the clogging zone, slower dissipation of excess pore pressure, and slower consolidation of the dredged sludge. As the volume compressibility of the dredged sludge increases, the consolidation rate gradually decreases. A smaller PVD radius of influence results in a faster consolidation rate. Therefore, in practical projects, the consolidation rate can be increased by appropriately reducing the spacing of the PVDs. However, further reducing the spacing of the PVDs has limited effect on improving the consolidation rate after reaching a certain threshold. The permeability coefficient of the non-clogging zone of dredged sludge significantly affects the consolidation rate. As the permeability coefficient of the non-clogging zone increases, the consolidation rate significantly increases. Therefore, in practical projects, it is worth considering conditioning the dredged sludge during the sludge removal process to increase the permeability coefficient. This can provide guidance for shortening the vacuum preloading project period.

[0158] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A real-time monitoring method for clogging effect, characterized in that: The real-time monitoring method for the clogging effect includes: Multiple groups of pore water pressure sensor arrays are arranged around the plastic drainage board along the depth direction; wherein each group of the pore water pressure sensor array includes at least three sensors distributed along the radial direction, which are used to collect excess pore water pressure data at different radial positions and depths in real time; Based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the siltation area is calculated. s and permeability coefficient distribution k s (r), complete the real-time monitoring data collection; among them, the permeability coefficient attenuation model is:

2. The method for real-time monitoring of clogging effect according to claim 1, characterized in that: The step of arranging multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction includes: A group of the pore water pressure sensor array is arranged every 0.5m along the depth direction, and the distance between two radially adjacent sensors in each group of the pore water pressure sensor array is 0.2rh to 0.5rh, where rh is the radius of the influence area of ​​the plastic drainage board; the sensor data sampling frequency is not less than 1 time / minute, and is uploaded to the control terminal in real time through the wireless transmission module.

3. The method for real-time monitoring of clogging effect according to claim 1, wherein: Before the step of distributing multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction, wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed along the radial direction for collecting excess pore water pressure data at different radial positions and depths in real time, the method further includes: In the initial stage of vacuum preloading, tracers are injected into the dredged sludge, and the diffusion rate of the tracer concentration is monitored by sensors to invert the initial permeability coefficient k0.

4. The method for real-time monitoring of clogging effect according to claim 1, wherein: Based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the siltation area is calculated. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises: Calculate the average degree of consolidation of dredged silt; adjusting the vacuum pressure according to the average degree of consolidation of the dredged sludge; If the average degree of consolidation of the dredged sludge is lower than a preset threshold, increasing the vacuum pressure; If the average degree of consolidation of the dredged sludge is higher than a preset threshold, the vacuum pressure is reduced.

5. The method for real-time monitoring of clogging effect according to claim 4, characterized in that: The step of calculating the average degree of consolidation of dredged silt comprises: According to the formula Calculate the degree of consolidation of each layer in real time.

6. The method for real-time monitoring of clogging effect according to claim 1, wherein: Before the step of distributing multiple groups of pore water pressure sensor arrays around the plastic drainage board along the depth direction, wherein each group of the pore water pressure sensor arrays includes at least three sensors distributed along the radial direction for collecting excess pore water pressure data at different radial positions and depths in real time, the method further includes: Add a conditioning agent to the dredged sludge, wherein the conditioning agent is composed of rice husk ash, carbide slag and polyaluminium chloride in a mass ratio of 60-80:20-30:5-10, and the addition amount is 3% to 5% of the dry mass of the dredged sludge; after addition, the conditioning agent is uniformly mixed through a stirring device to increase the permeability coefficient k of the non-clogging area. h To 1.5 to 2 times the initial value.

7. The method for real-time monitoring of clogging effect according to claim 6, characterized in that: The particle size distribution of the rice husk ash meets the following requirements: more than 90% of the particles have a particle size of less than 0.075 mm and a loss on ignition of no more than 8%; the CaO content of the carbide slag is ≥ 65% and the specific surface area is 400-600 m 2 / kg.

8. The method for real-time monitoring of clogging effect according to any one of claims 1 to 7, characterized in that: Based on the excess pore water pressure data and the preset permeability coefficient attenuation model, the real-time radius r of the siltation area is calculated. s and permeability coefficient distribution k s (r), after completing the step of collecting data for real-time monitoring, the method further comprises: When rh>0.6, the warning signal is triggered and the high-pressure water jet device is started to flush the PVD surface blockage layer at a pressure of 5-10 MPa, and the flushing time is 10-15 minutes / cycle.

9. The method for real-time monitoring of clogging effect according to claim 8, characterized in that: The water flow of the high-pressure water jet device contains 0.1% to 0.3% by mass of sodium lauryl sulfate, and the water temperature is controlled at 40 to 50°C.

10. The method for real-time monitoring of clogging effect according to claim 8, wherein: When rh>0.6, the warning signal is triggered and the high-pressure water jet device is started to flush the PVD surface blockage layer at a pressure of 5-10 MPa. The flushing time is 10-15 minutes / cycle. The steps include: After the high-pressure water jet flushing, the real-time radius r of the clogging area is recalculated. s , until r s ≤0.4rh.

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