A method for directional grouting repair of scour and erosion zones in wharf foundations

Abstract

This invention discloses a method for directional grouting repair of scour-filled areas in wharf foundations, comprising: S1, conducting surveys and data collection of the area to be grouted before directional grouting; S2, designing a grouting scheme, including: S21, estimating the required grouting volume for the area to be grouted; S22, designing the grouting hole positions and spacing; S23, initially assessing the grouting influence radius under given grouting pressure and flow rate conditions, thereby guiding the hole spacing and grouting volume distribution; S24, designing an upper limit for grouting pressure, ensuring that the upper limit is less than the critical rupture pressure of the soil or less than the allowable bearing capacity of the wharf structure; S3, selecting grouting materials and proportioning them; S4, carrying out grouting construction, including: S41, drilling; S42, test grouting; S43, formal grouting; S5, monitoring and quality assessment. This invention enables precise filling and foundation reinforcement of scour-filled areas.

Description

Technical Field

[0001] This invention belongs to the field of port and coastal engineering technology, and specifically relates to a method for directional grouting repair of scour and erosion zones in wharf foundations. Background Technology

[0002] Currently, the following repair methods are mainly used in engineering to address scour or erosion damage to the wharf foundation:

[0003] (1) Stone or sand backfilling method: The bearing capacity of the subgrade is restored by throwing crushed stone, boulders or sand into the cavitated area of ​​the subgrade.

[0004] (2) Underwater concrete sealing method: underwater concrete is poured in the scour area to form a reinforcement layer to block further scouring by seawater;

[0005] (3) Traditional grouting reinforcement method: By setting up grouting holes in the foundation, cement grout, chemical grout, etc. are injected into the subgrade to fill the voids and improve the soil strength.

[0006] Although the above methods can improve the condition of the substrate to some extent, they still have the following shortcomings:

[0007] (1) Lack of precise repair capability for cavitation areas: Existing methods are difficult to accurately determine the extent of cavitation areas and the grouting diffusion path, which can easily lead to "incomplete filling" or "grout loss".

[0008] (2) Construction disturbance is significant and has a clear impact on the normal operation of the wharf: large-scale reclamation or underwater construction often requires port closure or operation restriction;

[0009] (3) Grouting effect is difficult to evaluate and control: Grouting pressure, grouting flow rate and filling fullness rely heavily on construction experience and lack effective construction feedback and quality judgment mechanism;

[0010] (4) Insufficient long-term stability after repair of the scour zone of the subgrade: Some repair methods have failed to effectively improve the integrity of the subgrade structure, and it is still easy to be scoured or subsided again in the later stage.

[0011] Therefore, there is an urgent need for a directional grouting repair method for the scour and hollow areas of the wharf foundation, so as to achieve precise filling of the hollow areas and foundation reinforcement, thereby improving the service reliability of the wharf structure. Summary of the Invention

[0012] To address the aforementioned problems in the prior art, this invention provides a directional grouting repair method for scourd-out areas of wharf foundations, which can achieve precise filling of scourd-out areas and foundation reinforcement, thereby improving the service reliability of wharf structures.

[0013] The present invention adopts the following technical solution:

[0014] A method for directional grouting repair of scour and erosion zones in wharf foundations includes:

[0015] S1. Before directional grouting, conduct surveys and data collection on the underwater grouting area;

[0016] S2. Design the grouting scheme, including:

[0017] S21. Estimate the required grouting volume for the area to be grouted; specifically, include estimating the required grouting volume for the scour zone and / or erosion zone.

[0018] S22. Design the location and spacing of grouting holes;

[0019] S23. Preliminary assessment of the grouting influence radius under given grouting pressure and flow rate conditions, thereby guiding the hole spacing and grouting volume distribution;

[0020] S24. Design the upper limit of grouting pressure so that the upper limit of grouting pressure is less than the critical rupture pressure of the soil or less than the allowable bearing capacity of the wharf structure.

[0021] S3. Selection of grouting materials and proportioning of grouting materials, including:

[0022] S31. Select a suitable slurry type;

[0023] S32. Test mix the slurry;

[0024] S33. Obtain the grouting permeability parameters, which are used to calculate the seepage rate of the grout in the soil.

[0025] S4. Perform grouting in stages, including:

[0026] S41. Drilling: Drill grouting holes according to the designed grouting hole positions;

[0027] S42. Test grouting: In each section of the grouting hole, a small flow rate of grout is first injected as a test. By recording the grouting pressure and the cumulative grouting volume, the grouting response and permeability characteristics of the soil are judged.

[0028] S43. Conduct formal grouting, including:

[0029] S431. Segmented grouting: Starting from the deepest grouting hole or the outermost grouting hole, inject grout layer by layer into each hole; inject grout into each grouting hole according to the set segment length, and record the grouting pressure, grouting flow rate, cumulative grouting volume and grout backflow status.

[0030] S432, Dynamic control grouting: When the current grouting section is saturated, stop grouting in the current grouting hole and switch to grouting in the adjacent grouting hole;

[0031] S5. Conduct monitoring and quality assessment, including:

[0032] S51. Monitoring: including monitoring grouting pressure, grouting flow rate, cumulative grouting volume, changes in subgrade elevation, and pore water pressure;

[0033] S52. Quality Judgment: When grouting in the designated area is completed and meets the following mandatory condition A1, and simultaneously meets at least one of the optional conditions A2 or A3, the grouting quality is considered qualified:

[0034] Condition A1: The cumulative grouting volume of a single hole or single section is close to the design grouting volume, and the grouting backflow stops.

[0035] Condition A2: After grouting, testing shows that the voids in the scourged area have been filled or the foundation elevation has been restored. ;in This represents the elevation rise of the subgrade bed after grouting relative to before grouting. The target rise threshold for the subgrade elevation is set.

[0036] Condition A3: After grouting, the change in pore water pressure did not exceed the allowable range, and there were no abnormalities in the monitoring of the wharf structure;

[0037] S53. Conduct strength or durability tests: Collect grouting samples or core samples to conduct compressive strength or solidification tests. Only after the design strength is met can the grouting-formed structure in the grouting area (such as the hollow area) be considered to meet the long-term use requirements.

[0038] Further, step S1 includes:

[0039] S11. Determine the location, geometry, porosity, soil parameters, and hydrological conditions of the scour zone;

[0040] S12. Exploration work includes:

[0041] Multibeam sonar is used for detection to obtain a digital elevation model of the seabed; and / or side-scan sonar is used for detection to obtain acoustic images of the seabed;

[0042] Subbottom profilers are used to obtain shallow seabed reflection profiles to identify changes in overburden thickness, loose interlayers, or reflection characteristics of suspected cavities, and to help determine the boundaries and thickness of scour zones.

[0043] Use a water-based drilling rig or platform to drill holes and collect soil samples and borehole logs;

[0044] In-situ testing was conducted in the borehole sampling area to invert the equivalent strength and permeability classification of the soil.

[0045] A pore water pressure gauge is installed in the subgrade to output the pore pressure time history, which is used for the upper limit of grouting pressure and safety verification.

[0046] S13. Data is automatically output by the data processing terminal, including:

[0047] Output the hollow or loose thickness distribution;

[0048] Output void ratio or porosity;

[0049] Output the effective permeability coefficient of the substrate;

[0050] The output affects the thickness of the soil layer used for grouting;

[0051] Output the initial bed surface elevation.

[0052] Furthermore, in step S21, the required grouting volume for the emptied area is estimated using the following method:

[0053] The planar region of the emptying area is determined as follows The thickness of the void is The theoretical grouting volume required to fill the empty zone is... Calculate using the following integral formula:

[0054] ;

[0055] in, It is a plane coordinate; It is a plane coordinate; It is an area micro-element;

[0056] Total grouting design volume The required grouting volume for the emptied area is calculated using the following formula:

[0057] ;

[0058] in, The effective filling coefficient for grouting is 0. 1.

[0059] Further, in step S22, the spacing of the grouting holes needs to be determined; wherein the spacing of the grouting holes... The following formula must be satisfied:

[0060] ;

[0061] in, The effective grouting radius; the effective grouting radius According to the radius of influence of grouting Confirm, i.e. ;

[0062] In step S23, the radius of influence of grouting Calculate using the following formula:

[0063] ;

[0064] in, The radius of the grouting hole, in units of ; It is an exponential function; The slurry diffusivity is expressed in units of... ; The unit is the difference in head between the injection point and the far-field point. ; The instantaneous volumetric flow rate during grouting is expressed in units of... ;

[0065] Among them, slurry diffusivity The following relationship exists:

[0066] ;

[0067] in, The slurry permeation velocity per unit soil layer thickness is expressed in units of 1000 m³ / s. ; To effectively grout, the thickness is affected.

[0068] Furthermore, in step S24, the upper limit of the grouting pressure The following relationship must be satisfied:

[0069] ;

[0070] in, It is a function that takes the minimum value; It is the critical failure pressure of the soil. This is the allowable load-bearing capacity of the wharf structure;

[0071] Among them, the critical failure pressure of soil Calculated according to the following formula:

[0072] ;

[0073] in, This represents the minimum principal stress in the field. This refers to the tensile strength or shear strength of the soil.

[0074] Furthermore, in step S432, under constant pressure grouting conditions, i.e. at the target pressure... The grouting pressure was collected in real time. Data and grouting flow rate data;

[0075] Define time The rate of change of grouting flow rate within the cavity is expressed by the following formula:

[0076] ;

[0077] When any of the following conditions are met, it is determined that the grouting of the set hole section has reached saturation, and the "stop grouting or rotate hole" operation is executed;

[0078] Condition C1: ,and Continuous setting time ;

[0079] Condition C2: Continued to rise, and ;

[0080] Condition C3: Cumulative grouting volume To achieve the designed grouting volume for the set hole section The flow rate increased several times, and the reflux stopped.

[0081] in, It is a dimensionless coefficient; Pressure tolerance, used to describe Approaching target pressure Allowable deviation;

[0082] The minimum threshold for determining traffic flow;

[0083] This is the duration threshold;

[0084] The threshold for the rate of change of grouting flow rate, when At that time, it indicates a significant decrease in grouting flow rate;

[0085] is the grouting volume compliance coefficient for a single hole section, and is a dimensionless coefficient.

[0086] Furthermore, step S43 further includes: S433, grouting is performed using an alternating grouting method according to the actual situation; step S433 includes the following steps:

[0087] D1. Grouting;

[0088] D2. Let stand;

[0089] D3. Grouting;

[0090] Based on the actual situation, the D1 step is repeated to the D3 step; wherein, in the D2 step, the time required for settling is estimated based on the soil permeability coefficient.

[0091] Furthermore, the maximum allowable grouting pressure is set as follows: Therefore, in step S433, the condition for ending the grouting is:

[0092] When grouting pressure Or the cumulative grouting volume per hole End grouting of the designated grouting holes;

[0093] in, This refers to the grouting pressure. This represents the cumulative grouting volume per hole. The design standard value for the cumulative grouting volume per hole.

[0094] Furthermore, step S4 also includes: S44, monitoring the grouting process and recording relevant data, and uploading the relevant data to the control console for real-time adjustment of the grouting; wherein, recording the relevant data includes at least:

[0095] The grouting pressure, grouting flow rate, cumulative grouting volume, and grouting time of each grouting hole were continuously recorded.

[0096] Furthermore, a method for directional grouting repair of scour-filled areas in a wharf foundation also includes: S6, construction acceptance; the S6 step includes at least:

[0097] Verify the grouting records;

[0098] The seabed conditions were re-measured using sonar or subsea profilers;

[0099] Local drilling or diving inspections are conducted on the grouting structure in the grouting area.

[0100] Monitoring and comparison of settlement of the wharf structure.

[0101] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0102] This invention discloses a directional grouting repair method for scour-filled areas of wharf foundations. Step S1 obtains the spatial geometric characteristics of the area to be grouted (e.g., the scour-filled area), and step S21 determines the required grouting volume for the area. This invention enables quantitative control of the grouting location, grouting range, and grouting volume in the scour-filled area, achieving precise repair and avoiding waste of grouting materials and repair failure caused by blind grouting. This invention significantly improves the success rate of scour-filled area repair.

[0103] In step S23 of this invention, the influence radius of grouting is initially assessed, thereby guiding the allocation of grouting hole locations and grouting volume; step S24 enables the constraint of the upper limit of grouting pressure; and step S432 enables dynamic control of grouting. This invention can constrain the grouting flow rate, the upper limit of grouting pressure, and the influence radius of grouting, ensuring that the grouting process is carried out within a safe pressure range and avoiding secondary damage to the foundation bed and the upper wharf structure.

[0104] This invention is highly adaptable and can flexibly adjust grouting according to different geological conditions and subgrade scour patterns. For subgrade conditions with different particle size composition, pore structure and scour patterns, this invention can be adapted by adjusting the grouting hole spacing in step S22, and by adjusting the grout type and grout ratio in step S3. Grouting can be carried out according to the grouting method in step S43. This effectively avoids the problem of poor adaptability of traditional single grouting process under complex geological conditions, and significantly improves the versatility and engineering adaptability of this method.

[0105] The present invention’s S432 step dynamically controls grouting, which significantly improves the controllability of construction; the present invention’s S51 step can collect grouting pressure, grouting flow rate, cumulative grouting volume and subgrade elevation changes during construction. This information monitoring is conducive to the smooth progress of grouting and to ensuring the uniformity of grouting.

[0106] Step S52 of this invention can determine the repair quality after grouting in the cavitated area, effectively avoiding the problem of "hidden works being unverifiable or difficult to verify" and improving the reliability of grouting repair in the cavitated area.

[0107] This invention enables precise filling and foundation reinforcement of caving areas to improve the service reliability (including long-term stability) of wharf structures. Attached Figure Description

[0108] The technology of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0109] Figure 1 This is a cross-sectional schematic diagram of the scour and erosion zone of the wharf foundation.

[0110] Figure 2 This is a schematic cross-sectional view of the repaired scour zone of the wharf foundation.

[0111] Figure label:

[0112] 1-Wharf structure; 2-Foundation bed; 3-Cavitation zone; 4-Grouting hole location; F-Water surface. Detailed Implementation

[0113] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The same reference numerals used throughout the accompanying drawings indicate the same or similar parts.

[0114] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "up," "down," "left," and "right" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0115] Reference Figure 1 and Figure 2 A method for directional grouting repair of scour and erosion zones in wharf foundations, comprising:

[0116] S1. Before directional grouting, conduct surveys and data collection on the subsea area (e.g., below the water surface F); specifically, this may include surveying and data collection on the scour zone and / or erosion zone of the subgrade.

[0117] S2. Design the grouting scheme, including:

[0118] S21. Estimate the required grouting volume for the area to be grouted; specifically, include estimating the required grouting volume for the scour zone and / or erosion zone.

[0119] S22, Design grouting hole positions and spacing;

[0120] S23. Preliminary assessment of the grouting influence radius under given grouting pressure and flow rate conditions, thereby guiding the hole spacing and grouting volume distribution;

[0121] S24. Design the upper limit of grouting pressure so that the upper limit of grouting pressure is less than the critical rupture pressure of the soil (such as the subgrade soil) or less than the allowable bearing capacity of the wharf structure.

[0122] S3. Selection of grouting materials and proportioning of grouting materials, including:

[0123] S31. Select a suitable slurry type;

[0124] S32. Test mix the slurry;

[0125] S33. Obtain grouting permeability parameters, which are used to calculate the permeability rate of grout in soil (such as subgrade soil); wherein, the grouting permeability parameters can be obtained by measuring the grout viscosity or by a permeability test or by existing empirical tables;

[0126] S4. Perform grouting in stages, including:

[0127] S41. Drilling: Drill grouting holes at grouting hole position 4 as designed in step S22; wherein, a bottom plug or a hole expander can be installed at the bottom of the grouting hole to ensure directional diffusion of grout; the grouting pipe must have the ability to perform layered grouting and can release grout at different depths;

[0128] S42. Test grouting (also known as pilot grouting): In each section of the grouting hole, a small flow rate of grout is first injected as a test. By recording the grouting pressure and cumulative grouting volume, the grouting response and permeability characteristics of the soil are judged, which can be used to correct subsequent grouting parameters (such as grouting hole position 4, grouting pressure, and grouting flow rate).

[0129] S43. Conduct formal grouting, including:

[0130] S431. Segmented grouting: Starting from the deepest grouting hole 4 or the outermost grouting hole 4, inject grout layer by layer into each hole; inject grout into each grouting hole according to the set segment length, and record the grouting pressure, grouting flow rate, cumulative grouting volume and grout backflow.

[0131] S432, Dynamic control grouting: During the grouting process, using " "Function curve graph, " Using the function curve graph as a guide, it is generally considered that the set hole section has been saturated when "the grouting pressure rises while the grouting flow rate drops significantly or stops" occurs under constant pressure grouting; among them, " The function curve graph represents the grouting pressure. Over time The continuous change, among which, It is the ordinate of the function curve graph. It is the x-coordinate of the function curve graph; The function curve graph represents the grouting flow rate. Over time The continuous change, among which, It is the ordinate of the function curve graph. It is the x-coordinate of the function curve graph;

[0132] If the current grouting section is saturated, stop grouting in the current grouting hole and switch to grouting in the adjacent grouting hole;

[0133] Step S4 of the present invention can be performed without significantly disrupting the normal operation of the terminal, thus reducing the impact on the normal operation of the terminal.

[0134] S5. Conduct monitoring and quality assessment, including:

[0135] S51. Monitoring: This includes monitoring grouting pressure, grouting flow rate, cumulative grouting volume, changes in subgrade elevation, and pore water pressure (in the subgrade soil); if there is displacement or tilting of wharf structure 1, it also includes monitoring the amount of displacement or tilting of wharf structure 1.

[0136] S52. Quality Judgment: Grouting of the designated area (e.g., empty zone 3) is considered qualified if the grouting is completed and meets the following mandatory condition A1, and at least one of the optional conditions A2 or A3 is also met:

[0137] Condition A1: The cumulative grouting volume of a single hole or single section is close to the design grouting volume, and the grouting backflow stops.

[0138] Condition A2: After grouting, testing showed that the voids in the scourd area 3 had been filled or the foundation elevation had been restored. ;in This represents the elevation rise of the subgrade bed after grouting relative to before grouting. The target rise threshold for the subgrade elevation is set.

[0139] Condition A3: After grouting, the change in pore water pressure (in the subgrade soil) did not exceed the allowable range, and there were no abnormalities in the monitoring of the wharf structure;

[0140] Note: During construction, it is necessary to control the pore water pressure to avoid a sharp increase in pore water pressure due to construction disturbance, which could lead to soil instability. In step S52, if the grouting quality is found to be unqualified after quality assessment, the designated area (such as the cavitated area) needs to be grouted or the grouting range needs to be expanded.

[0141] S53. Conduct strength or durability tests: Collect grouting samples or core samples (referring to taking "grouting-formed structural blocks") to conduct compressive strength or solidification tests. Only after meeting the design strength can the grouting-formed structure in the grouting area (such as the hollowed-out area 3) be considered to meet the long-term use requirements.

[0142] This invention can be applied to the scour and erosion zones of gravity-type wharf foundations, sheet pile wharf foundations, and high-pile wharf foundations.

[0143] In one embodiment, step S1 includes:

[0144] S11. Determine the location, geometry, porosity, soil parameters, and hydrological conditions of the scour zone 3. This step S11 provides prior parameters for grouting design (including grouting volume calculation).

[0145] S12. Exploration work includes:

[0146] Multibeam sonar is used to obtain a digital elevation model (DEM) of the seabed. Specifically, a survey vessel or unmanned survey vessel can be equipped with multibeam sonar to obtain the DEM, which is used to identify scour pits and elevation change zones, and to serve as a comparison benchmark before and after grouting. And / or, side-scan sonar is used to obtain seabed acoustic images, which are used to identify anomalous textures such as loose deposits, foreign objects, and thin layers overlying cavities.

[0147] Subbottom profilers are used to obtain shallow seabed reflection profiles to identify changes in overburden thickness, loose interlayers, or suspected cavitation reflection characteristics, and to help determine the boundary and thickness of scour zone 3.

[0148] Using a water-based drilling rig or platform, boreholes are drilled to collect soil samples (such as subgrade soil) and to record the soil samples. Further, the soil particle size, soil porosity, and initial moisture content of the soil samples are obtained.

[0149] In-situ testing is conducted in the borehole sampling area to invert the equivalent strength and permeability classification of soil (such as subgrade soil). Specifically, in-situ testing can be performed using the Standard Penetration Test (SPT) or the Cone Penetration Test (CPT). In-situ means that the test is located in the same location as or adjacent to the borehole used for "borehole sampling".

[0150] A pore water pressure gauge is installed in the subgrade to output the pore pressure time history, which is used for the upper limit of grouting pressure and safety verification.

[0151] S13. Data is automatically output by (several existing) data processing terminals (such as sonar terminals and / or subsurface profiler terminals and / or grouting design module terminals), including:

[0152] Output the void or loose thickness distribution (which is the "void thickness field" below) The "vacuuming or loose thickness distribution" can be derived from the foundation digital elevation model of the subgrade and the bottom boundary interpretation of the subbase profile through joint inversion.

[0153] Output voids or porosity; this "voids or porosity" can be obtained from a borehole sampling test;

[0154] Output the effective permeability coefficient of the substrate; this "effective permeability coefficient of the substrate" can be obtained from in-situ testing;

[0155] Output the soil layer thickness that affects grouting; this "soil layer thickness that affects grouting" can be obtained from in-situ testing;

[0156] Output the initial subgrade bed elevation; this "initial subgrade bed elevation" can be obtained from the subgrade digital elevation model.

[0157] Output the lateral boundary distance of the cavitation zone; this "lateral boundary distance of the cavitation zone" can be obtained by joint analysis of the subgrade digital elevation model and the sub-bottom profile.

[0158] Reference Figure 1 In one embodiment, step S21 includes estimating the required grouting volume for the emptying zone 3, using the following method:

[0159] The planar region of the emptying area is determined as follows The thickness of the void is The theoretical grouting volume required to fill the empty zone 3 is... Calculate using the following integral formula:

[0160] ;

[0161] in, It is a plane coordinate; It is a plane coordinate; As the integrand of a double integral; It is an area micro-element;

[0162] Total grouting design volume The required grouting volume for empty zone 3 (actual) is calculated using the following formula:

[0163] ;

[0164] in, The effective filling coefficient for grouting is 0. 1. The The value of depends on the permeability of the soil and grout, and is usually taken as 0.6 to 0.95.

[0165] In one embodiment, in step S22, the spacing of the grouting holes needs to be determined; wherein the spacing of the grouting holes... The following formula must be satisfied:

[0166] ;

[0167] In actual engineering projects, it is generally based on The values ​​are selected to ensure that after grouting adjacent holes, the grout in the bottom grouting area (such as in the hollowed-out area) can cover each other;

[0168] in, The effective grouting radius; the effective grouting radius According to the radius of influence of grouting Confirm, i.e. ;

[0169] In step S23, the radius of influence of grouting Calculate using the following formula:

[0170] ①;

[0171] in, The radius of the grouting hole, in units of ; It is an exponential function; The slurry diffusivity is expressed in units of... ; The unit is the difference in head between the injection site and the far-field head (equivalent head to grouting pressure). ; The instantaneous volumetric flow rate during grouting is expressed in units of... ;

[0172] Among them, slurry diffusivity The following relationship exists:

[0173] ;

[0174] in, The slurry permeation velocity per unit soil layer thickness is expressed in units of 1000 m³ / s. ; To effectively grout, the thickness is affected.

[0175] Formula ① above is used to preliminarily assess the theoretical diffusion radius of the grout under given grouting pressure and flow rate conditions, i.e., the "radius of influence R of grouting," thereby guiding the spacing between grouting holes and the distribution of grout volume. Formula ① is derived from steady-state formula ②. Actual grouting is a non-steady-state process; if a more accurate radius of influence is desired, it needs to be adjusted in a timely manner based on actual conditions. Generally, the radius of influence of grouting can be directly calculated using formula ① (an estimation method).

[0176] The steady-state formula ② is as follows:

[0177] ②.

[0178] in, The instantaneous volumetric flow rate during grouting is expressed in units of... ; The slurry diffusivity is expressed in units of... ; The unit is the difference in head between the injection site and the far-field head (equivalent head to grouting pressure). ; The radius of the grouting hole, in units of ; The radius of influence of grouting, in units of .

[0179] Formula ② above is the classical formula for steady radial flow.

[0180] In one embodiment, in step S24, the upper limit of the grouting pressure The following relationship must be satisfied:

[0181] ③;

[0182] in, It is a function that takes the minimum value; It is the critical failure pressure of the soil. This is the allowable load-bearing capacity of the wharf structure;

[0183] Among them, the critical failure pressure of soil Calculated according to the following formula:

[0184] ;

[0185] in, This represents the minimum principal stress in the field. This refers to the tensile strength or shear strength of the soil.

[0186] Formula ③ above can effectively avoid the risk of soil fracturing or uplift to the wharf structure caused by grouting. Step S42 of this invention verifies the upper limit of the grouting pressure through a small-scale grouting test, ensuring the safety of formal grouting construction. The grouting pressure should avoid causing adverse uplift risks to the wharf structure; if necessary, temporary counterweights should be applied to the wharf structure before and after grouting.

[0187] In one embodiment, step S31 includes at least:

[0188] Select cement-based cement grout (such as cement-fly ash grout).

[0189] Use fine particle slurry;

[0190] Chemical pulp should be selected.

[0191] The selection criteria for step S31, "selecting a suitable grout type," include: grout permeability, grout setting time, strength development performance during grout molding, and durability and environmental compatibility after grout molding.

[0192] In one embodiment, in step S432, under constant pressure grouting conditions, i.e. at the target pressure... The grouting pressure was collected in real time. Data and grouting flow rate data;

[0193] Define time The rate of change of grouting flow rate within the cavity is expressed by the following formula:

[0194] ;

[0195] When any of the following conditions are met, it is determined that the grouting of the set hole section has reached saturation, and the "stop grouting or rotate hole" operation is executed;

[0196] Condition C1: ,and Continuous setting time ;

[0197] Condition C2: Continued to rise, and ;

[0198] Condition C3: Cumulative grouting volume To achieve the designed grouting volume for the set hole section The flow rate increased several times, and the reflux stopped.

[0199] in, It is a dimensionless coefficient, determined based on the actual situation; Pressure tolerance, used to describe Approaching target pressure Allowable deviation;

[0200] The minimum threshold for determining flow rate, in units of ;

[0201] This is the duration threshold, in seconds;

[0202] The threshold for the rate of change of grouting flow rate, in units ,when At that time, it indicates a significant decrease in grouting flow rate;

[0203] It is the grouting volume compliance coefficient for a single hole section, which is a dimensionless coefficient, usually taken as 0.9 to 1.1.

[0204] The aforementioned threshold can be determined during the test grouting process in step S42.

[0205] In one embodiment, when the grouting of the set hole section has become saturated, the following operations are performed: first, stop grouting, then depressurize the current grouting hole, record relevant data (such as depressurization data) during the process, and then switch the grouting pipe to the adjacent grouting hole; wherein, the current grouting hole and the adjacent grouting hole have been designed in advance in step S22.

[0206] In one embodiment, step S43 further includes: S433, grouting is performed using an alternating grouting method according to the actual situation; step S433 includes the following steps:

[0207] D1. Grouting;

[0208] D2. Let stand;

[0209] D3. Grouting;

[0210] Based on the actual situation, the process is repeated from step D1 to step D3. If foreign matter backflow or grout overflow occurs, the grouting process should be stopped and dealt with promptly. In step D2, the time required for settling is estimated based on the soil permeability coefficient.

[0211] In one embodiment, the maximum allowable grouting pressure is set to Therefore, in step S433, the condition for ending the grouting is:

[0212] When grouting pressure Or the cumulative grouting volume per hole End grouting of the designated grouting holes;

[0213] in, This refers to the grouting pressure. This represents the cumulative grouting volume per hole. The design standard value for the cumulative grouting volume per hole.

[0214] In one embodiment, step S4 further includes: S44, monitoring the grouting process and recording relevant data, and uploading the relevant data to the control console for real-time adjustment of the grouting; wherein, recording the relevant data includes at least:

[0215] The grouting pressure, grouting flow rate, cumulative grouting volume, and grouting time of each grouting hole were continuously recorded.

[0216] Monitoring the grouting process includes at least monitoring surface or underwater subsidence and monitoring changes in sonar echo profiles.

[0217] In one embodiment, a method for directional grouting repair of scour and erosion zones in a wharf foundation further includes: S6, construction acceptance; the S6 step includes at least:

[0218] Verify the grouting records;

[0219] The seabed conditions were re-measured using sonar or subsea profilers;

[0220] Local drilling or diving inspections are conducted on the grouting structure in the grouting area (such as the cavitation zone);

[0221] Monitoring and comparison of settlement of the wharf structure.

[0222] In one embodiment, a method for directional grouting repair of a wharf foundation scour zone further includes: S7, periodically inspecting the repaired scour zone; such as periodically (e.g., monthly or quarterly) performing depth measurements and sonar echo checks on the repaired scour zone, while simultaneously monitoring the pore water pressure of the foundation soil and the displacement of the wharf structure, to ensure that the grouting-formed structure of the repaired scour zone has not been washed away by seawater or to ensure that there are no new cavities in the repaired scour zone.

[0223] Other aspects of the directional grouting repair method for the scour and hollowed-out area of ​​the wharf foundation described in this invention can be found in the prior art and will not be repeated here.

[0224] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for directional grouting repair of scour and erosion zones in wharf foundations, characterized in that, include: S1. Before directional grouting, conduct surveys and data collection on the area to be grouted; S2. Design the grouting scheme, including: S21. Estimate the required grouting volume for the area to be grouted; S22. Design the location and spacing of grouting holes; S23. Preliminary assessment of the grouting influence radius under given grouting pressure and flow rate conditions, thereby guiding the hole spacing and grouting volume distribution; S24. Design the upper limit of grouting pressure so that the upper limit of grouting pressure is less than the critical rupture pressure of the soil or less than the allowable bearing capacity of the wharf structure. S3. Selection of grouting materials and proportioning of grouting materials, including: S31. Select a suitable slurry type; S32. Conduct trial mixing of the slurry; S33. Obtain the grouting permeability parameters, which are used to calculate the seepage rate of the grout in the soil. S4. Perform grouting in stages, including: S41. Drilling: Drill grouting holes according to the designed grouting hole positions; S42. Test grouting: In each section of the grouting hole, a small flow rate of grout is first injected as a test. By recording the grouting pressure and the cumulative grouting volume, the grouting response and permeability characteristics of the soil are judged. S43. Conduct formal grouting, including: S431. Segmented grouting: Starting from the deepest grouting hole or the outermost grouting hole, inject grout layer by layer into each hole; inject grout into each grouting hole according to the set segment length, and record the grouting pressure, grouting flow rate, cumulative grouting volume and grout backflow status. S432, Dynamic control grouting: When the current grouting section is saturated, stop grouting in the current grouting hole and switch to grouting in the adjacent grouting hole; S5. Conduct monitoring and quality assessment, including: S51. Monitoring: including monitoring grouting pressure, grouting flow rate, cumulative grouting volume, changes in subgrade elevation, and pore water pressure; S52. Quality Judgment: When grouting in the designated area is completed and meets the following mandatory condition A1, and simultaneously meets at least one of the optional conditions A2 or A3, the grouting quality is considered qualified: Condition A1: The cumulative grouting volume of a single hole or single section is close to the design grouting volume, and the grouting backflow stops. Condition A2: After grouting, testing shows that the voids in the scourged area have been filled or the foundation elevation has been restored. ;in This represents the elevation rise of the subgrade bed after grouting relative to before grouting. The target rise threshold for the subgrade elevation is set. Condition A3: After grouting, the change in pore water pressure did not exceed the allowable range, and there were no abnormalities in the monitoring of the wharf structure; S53. Conduct strength or durability tests: Collect grouting samples or core samples to conduct compressive strength or solidification tests. Only after the design strength is met can the grouting-formed structure in the grouting area be considered to meet the long-term use requirements.

2. The method for directional grouting repair of scour and hollow areas in a wharf foundation according to claim 1, characterized in that, Step S1 includes: S11. Determine the location, geometry, porosity, soil parameters, and hydrological conditions of the scour zone; S12. Exploration work includes: Multibeam sonar is used for detection to obtain a digital elevation model of the seabed; and / or side-scan sonar is used for detection to obtain acoustic images of the seabed; Subbottom profilers are used to obtain shallow seabed reflection profiles to identify changes in overburden thickness, loose interlayers, or reflection characteristics of suspected cavities, and to help determine the boundaries and thickness of scour zones. Use a water-based drilling rig or platform to drill holes and collect soil samples and borehole logs; In-situ testing was conducted in the borehole sampling area to invert the equivalent strength and permeability classification of the soil. A pore water pressure gauge is installed in the subgrade to output the pore pressure time history, which is used for the upper limit of grouting pressure and safety verification. S13. Data is automatically output by the data processing terminal, including: Output the hollow or loose thickness distribution; Output void ratio or porosity; Output the effective permeability coefficient of the substrate; The output affects the thickness of the soil layer used for grouting; Output the initial bed surface elevation.

3. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 1, characterized in that, Step S21 includes estimating the required grouting volume for the cavitated area, using the following method: The planar region of the emptying area is determined as follows The hole thickness field is The theoretical grouting volume required to fill the empty zone is... Calculate using the following integral formula: ； in, It is a plane coordinate; It is a plane coordinate; It is an area micro-element; Total grouting design volume The required grouting volume for the emptied area is calculated using the following formula: ； in, The effective filling coefficient for grouting is 0.

1.

4. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 1, characterized in that, In step S22, the spacing of the grouting holes needs to be determined; wherein the spacing of the grouting holes The following formula must be satisfied: ； in, The effective grouting radius; the effective grouting radius According to the radius of influence of grouting Confirm, i.e. ; In step S23, the radius of influence of grouting Calculate using the following formula: ； in, The radius of the grouting hole, in units of ; It is an exponential function; The slurry diffusivity is expressed in units of... ; The unit is the difference in head between the injection point and the far-field point. ; The instantaneous volumetric flow rate during grouting is expressed in units of... ; Among them, slurry diffusivity The following relationship exists: ； in, The slurry permeation velocity per unit soil layer thickness is expressed in units of 1000 m³ / s. ; To effectively grout, the thickness is affected.

5. The method for directional grouting repair of scour-filled areas in a wharf foundation according to claim 1, characterized in that, In step S24, the upper limit of grouting pressure The following relationship must be satisfied: ； in, It is a function that takes the minimum value; It is the critical failure pressure of the soil. This is the allowable load-bearing capacity of the wharf structure; Among them, the critical failure pressure of soil Calculated according to the following formula: ； in, This represents the minimum principal stress in the field. This refers to the tensile strength or shear strength of the soil.

6. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 1, characterized in that, In step S432, under constant pressure grouting conditions, i.e. at the target pressure... The grouting pressure was collected in real time. Data and grouting flow rate data; Define time The rate of change of grouting flow rate within the cavity is expressed by the following formula: ； When any of the following conditions are met, it is determined that the grouting of the set hole section has reached saturation, and the "stop grouting or rotate hole" operation is executed; Condition C1: ,and Continuous setting time ; Condition C2: Continued to rise, and ; Condition C3: Cumulative grouting volume To achieve the designed grouting volume for the set hole section The flow rate increased several times, and the reflux stopped; in, It is a dimensionless coefficient; Pressure tolerance, used to describe Approaching target pressure Allowable deviation; The minimum threshold for determining traffic flow; This is the duration threshold; The threshold for the rate of change of grouting flow rate, when At that time, it indicates a significant decrease in grouting flow rate; is the grouting volume compliance coefficient for a single hole section, and is a dimensionless coefficient.

7. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 1, characterized in that, Step S43 further includes: S433, grouting is performed using an alternating grouting method according to the actual situation; step S433 includes the following steps: D1. Grouting; D2. Let stand; D3. Grouting; Based on the actual situation, the D1 step is repeated to the D3 step; wherein, in the D2 step, the time required for settling is estimated based on the soil permeability coefficient.

8. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 7, characterized in that, Set the maximum allowable grouting pressure to Therefore, in step S433, the condition for ending the grouting is: When grouting pressure Or the cumulative grouting volume per hole End grouting of the designated grouting holes; in, This refers to the grouting pressure. This represents the cumulative grouting volume per hole. The design standard value for the cumulative grouting volume per hole.

9. The method for directional grouting repair of scour and erosion zones in a wharf foundation according to claim 1, characterized in that, Step S4 further includes: S44, monitoring the grouting process and recording relevant data, and uploading the data to the control console for real-time adjustment of the grouting; wherein, recording the relevant data includes at least: The grouting pressure, grouting flow rate, cumulative grouting volume, and grouting time of each grouting hole were continuously recorded.

10. A method for directional grouting repair of scour-filled areas in a wharf foundation according to any one of claims 1 to 9, characterized in that, Also includes: S6. Construction Acceptance; The S6 step includes at least the following: Verify the grouting records; The seabed conditions were re-measured using sonar or subsea profilers; Local drilling or diving inspections are conducted on the grouting structure in the grouting area. Monitoring and comparison of settlement of the wharf structure.

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